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  _LONGMANS’ CIVIL ENGINEERING SERIES_

  RAILWAY CONSTRUCTION




  LONGMANS’

  CIVIL ENGINEERING SERIES


NOTES ON DOCKS AND DOCK CONSTRUCTION.

  By C. COLSON, C.B., M.Inst.C.E., Deputy Civil Engineer-in-Chief,
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 LONGMANS, GREEN, AND CO.
 LONDON, NEW YORK, BOMBAY, AND CALCUTTA

  [Illustration:
  _Frontispiece._]  KINSUA VIADUCT, ERIE RAILWAY, U.S.A.  [_See p. 97._]




  _LONGMANS’ CIVIL ENGINEERING SERIES_

  RAILWAY CONSTRUCTION


  BY

  WILLIAM HEMINGWAY MILLS, M.INST.C.E.

  PAST PRESIDENT OF THE INSTITUTION OF CIVIL ENGINEERS OF IRELAND, AND
  ENGINEER-IN-CHIEF OF THE GREAT NORTHERN
  RAILWAY OF IRELAND

  [Illustration]

  _WITH ILLUSTRATIONS_

  FOURTH IMPRESSION

  LONGMANS, GREEN, AND CO.
  39 PATERNOSTER ROW, LONDON
  NEW YORK, BOMBAY, AND CALCUTTA
  1910

  _All rights reserved_




PREFACE


The construction and maintenance of a railway calls for the
application of so many branches of engineering that several volumes
would be required to do ample justice to a subject so comprehensive
and ever-extending. To avoid attempting so wide a range, the object of
the following pages has been to describe briefly some of the
recognized leading features which regulate railway construction, and
to assist the explanation with sketches of works selected from actual
practice.

Where the number of existing good examples is legion, it is somewhat
difficult to make a choice for illustration, and the course adopted
has been to select such samples of structures as appear best to
elucidate in a simple manner the different types of work under
consideration.

In the drawings and diagrams many important minor details are
necessarily omitted, partly to avoid complexity, but principally to
leave more prominent the leading features of the particular piece of
work referred to in the description. Some of the sketches of the large
span bridges and large span roofs are only shown in outline; but, as
their principal dimensions are given, a general idea can be obtained
of their actual proportions.

No allusion is made to the requisite strengths of the various
structures described, nor to the necessary dimensions of the materials
used in their construction, as this would necessitate the introduction
of a vast amount of mathematical formulæ which does not come under the
province of the object in view, and which the engineer has already at
command from his training and works of reference.

Neither is any mention made as to the probable cost of the different
works of construction, as these must always vary to a very large
extent, according to the locality, facility of supply, and current
prices of materials.

Every railway scheme which is the outcome of public enterprise has its
commercial aspect and influence. The large sums to be invested in its
construction are expected to yield permanent and increasing returns,
and this desirable end can only be attained where there is thorough
efficiency in works and equipment, and a full compliance with those
national regulations which control matters connected with public
safety. The correct dealing with the technical requirements and
structural features of the undertaking must always precede all other
considerations, as the constituted authorities will exact a proper
fulfilment of all the statutory obligations, regardless of the
prospective remuneration to the promoters. A stroke of the pen may
change a train-service, or alter the rates and tariffs, but a
modification in the works of construction arising out of errors or
oversight, would entail a heavy expenditure and tedious delay. The
essential point of every railway undertaking must be its suitability
and completeness in every respect for the duty for which it is
intended.

Notes of what has been done are always valuable for consideration and
comparison, and that the following brief description and sketches may
be found useful for reference, is the earnest wish of the writer.

  W. H. MILLS,
    M.INST.C.E.




  CONTENTS


  CHAPTER I.

                                                                 PAGE

  Location of a line of railway--Government regulations--Questions
  for consideration in connection with gauge, gradients, and
  curves                                                            1


  CHAPTER II.

  Works of construction: Earthworks, Culverts, Bridges,
  Foundations, Screw piles, Cylinders, Caissons, Retaining
  walls, and Tunnels                                               60


  CHAPTER III.

  Permanent way--Rails--Sleepers--Fastenings--and Permanent-way
  laying                                                          182


  CHAPTER IV.

  Stations: Station Buildings, Roofs, Lines, and Sidings          248


  CHAPTER V.

  Sorting-sidings--Turn-tables--Traversers--Water-Tanks and
  Water-Columns                                                   285


  CHAPTER VI.

  Comparative Weights of some Types of Modern Locomotives         304


  CHAPTER VII.

  Signals--Interlocking--Block Telegraph and Electric Train
  Staff Instruments                                               313


  CHAPTER VIII.

  Railways of different ranks--Progressive improvements--Growing
  tendency for increased speeds, with corresponding increase in
  weight of permanent way and rolling-stock--Electricity as a
  motive-power                                                    348

  INDEX                                                           361




  CHAPTER I.                                                                1

  Location of a line of railway--Government regulations--Questions
    for consideration in connection with gauge, gradients, and
    curves.


Location.--The locating of a line of railway, or the determination
of its exact route, is influenced by many circumstances. In a rich
country, with thickly populated districts and large industrial
enterprises, there are towns to be served, manufacturing centres to be
accommodated, and harbours to be brought into connection; while, at
the same time, there may be important estates which must be avoided
and private properties which must not be entered. Each point will
present its own individual claim for consideration when selecting the
route which promises the greatest amount of public convenience and
commercial success.

In new countries--in our colonies, and especially out in the far west
of Canada and the United States--railways have to be laid out in
almost uninhabited districts, where there is but little population or
commerce to serve, and where the principal object is to obtain the
best and most direct route through the vast territories, leaving
colonists and settlers to choose afterwards the most convenient sites
for towns and villages. Untrammelled by the network of public and
private roads and properties which are met with at home, it might
appear that the locating of such a line would be comparatively light;
but even in such countries, which at first sight seem to present
unlimited freedom for selecting a route, much can be done, and should
be done, by taking a course through those plains and districts which
possess the best natural resources for future agricultural,
manufacturing, or mineral development.

In addition to the motives of convenience and policy, the route of
every line of railway must be influenced by the natural features of
the country--the mountains, valleys, and rivers. These physical
obstacles are in some cases on such an enormous scale as to compel          2
long detours in the formation of a more suitable opening; and in
others, although the difficulties are not insurmountable, they may
involve works of great magnitude and expense.

In a comparatively rich country, with a prospect of large and
remunerative traffic, a succession of heavy works, bridges, and
tunnels may be admissible and expedient; but in new countries economy
of outlay has to be considered, and costly works avoided as much as
possible.

Every one of the heavy works on a line, whether lofty bridges, long
viaducts, or costly tunnels, not only enormously increase the original
expenditure of the undertaking, but also entail large annual outlay in
the necessary constant supervision and maintenance.

Each particular scheme will have to be discussed on its own individual
merits. The heavy, high-speed passenger traffic line will suggest
light gradients and easy curves, while on secondary lines and in
thinly populated districts it may be prudent, for the sake of economy,
to introduce sharper curves and heavier gradients. Even in the latter
case, and especially in new countries, it is well to keep in view the
future possibilities of the undertaking. The steeper the gradients,
the greater the cost and time in working the traffic, and if there is
every probability of early and large development, the prospective
increase may warrant an additional outlay in the original
construction.

Large, open plains and wide valleys of important rivers generally
afford ample latitude for the selection of a suitable route, and, by
taking advantage of the gradations of altitude, a favourable course
may be adopted without incurring excessive gradients. When traversing
moderately hilly districts, some low ridge or opening may be found,
which may form a pass from the one side to the other, and the line may
be laid out for a long distance to lead gradually up to the highest
point. But when a route has to be laid out over some of those lofty
mountain ranges which are met with abroad, the locating of a suitable
line, or of any line, becomes particularly intricate and difficult. A
comparatively low ridge may be found possessing features in favour of
the project, but the question will be how to reach that point. The
nearer the summit of these high mountains, the more precipitous the
sides; no one slope can be found sufficiently long and uniform to           3
permit a practical direct ascent, and the only way out of the
difficulty is to make a series of detours along the various spurs of
the mountains to gain length to overcome the height. Each detour has
to be the subject of most careful study. Forming part of a long series
of ascending gradients, it has to follow the winding of the
mountain-side, must be laid out to be always gaining in height, and
will comprise important works, many of them of considerable extent,
necessary for protection against the floods and atmospherical changes
of the locality.

In these higher altitudes nature is met with on the grandest and most
rugged scale. Deep gorges, wide ravines, and almost perpendicular
rocks form the pathway along which the line must be carried, and the
skill of the engineer is taxed to the utmost to select a course which
shall comprise a minimum of the works of magnitude. Mile after mile of
line must be laid out in almost inaccessible places, loose or broken
rocks must be avoided, a firm foundation must be obtained at all
points skirting high ledges, and ample provision must be made for
those mountain torrents which rise so suddenly, and are liable to
sweep away all before them.

Many grand examples of these detour lines are in existence in
different parts of the world, and the traveller passing over them can
realize the difficulties that had to be encountered, and the masterly
manner in which they have been overcome.

Before proceeding to carry out the works of any line of railway, it is
necessary to prepare a complete plan and section of the line, showing
the route to be followed and the position of the various curves,
gradients, and principal works. Within certain limits, the course of
the line may have to be slightly modified as the work proceeds, in
consequence of ground turning out unfavourable, river-crossings
treacherous, or of sites involving so many contingent alterations that
it is found better to avoid them altogether. The route should,
however, be so carefully studied out before completing the final plan
and section, as to leave only minor deviations of line and level to be
dealt with in the actual carrying out of the work.

The promoters of lines in the United Kingdom obtain valuable
assistance from the ordnance maps, which give full and reliable
information regarding the position of all roads, rivers, and
boundaries of counties, parishes, and townlands. In many parts abroad       4
local maps are scarce, and not always accurate, and engineers have to
depend principally on their own surveys, and rely upon the resident
local authorities for any particulars as to divisions of territory. On
some of our great colonial plains, and out in the far west of America,
a line may be laid out for miles without a single landmark to localize
it on a plan; but careful setting out, and the relative levels of the
ground and gradients, as shown on the section, will always indicate
the correct position of any portion of the work.

Both at home and abroad complete plans and sections of any proposed
railway must be deposited with the proper Government authorities, and
must be approved and sanctioned by them before permission can be
obtained to proceed with the works.

The regulations regarding the scale and general arrangement of these
plans and sections vary in different countries, and are subject to
modification from time to time.

Each country has its own special enactments relative to the method of
dealing with roads, rivers, streams, and public and private property
proposed to be interfered with in the construction of any line, and a
knowledge of these is absolutely necessary for the promoters of any
new scheme, inasmuch as some of the requirements may, in certain
instances, influence the precise route to be selected.

The English Government has passed several Acts of Parliament setting
forth the general conditions which must be complied with in the
construction of any railway in the United Kingdom. These conditions,
or standing orders, relate both to the acquirement of land and
property, the size and description of works for public or private
accommodation, and the inspection and official approval of the
undertaking when completed. These fixed regulations are alike valuable
to the promoters and to the public; the former are informed of the
principal points with which the scheme must conform, and the latter
know the limit of their legal demands.

No line of railway, or extension of any railway, will obtain
Parliamentary sanction unless it can be satisfactorily proved in the
outset, that its construction would be of public advantage. This point
is of paramount importance, and due weight must be given to it when
preparing to refute the evidence of opponents to the scheme.

[Illustration: Fig. 1.]

When conceding the right to make any railway, Parliament grants with        6
it the power to purchase lands or property compulsorily, or by
agreement, to change and divert roads and streams in the manner shown
on the deposited plans, and to construct all necessary bridges and
works in accordance with the standing orders, or such modifications of
them as may be approved by the Board of Trade.

The standing orders, or Government regulations, are very
comprehensive, and include much detailed information on all questions
likely to arise. The following brief summary of some of the principal
orders relating to deposited plans, and works of construction, will be
found useful for reference.


Extract from Government Standing Orders and Regulations.--All
plans and sections relative to proposed new railways must be lodged
with the constituted Government Authorities on or before November 30.

Every deposited plan must be drawn to a scale of not less than four
inches to a mile, and must describe the centre line, or situation of
the work (no alternative line being allowed), and must show all lands,
gardens, or buildings within the limits of deviation, each one being
numbered with a reference number, and where powers to make lateral
deviations are applied for, the limits of such deviation must be
marked on the plan.

Unless the whole of such plan be drawn to a scale of not less than 400
feet to an inch, an enlarged plan must be drawn to that scale of every
building and garden within the limits of deviation.

The Railway Clauses Act limits the extent of deviation to 100 yards on
each side of the centre line in the country, and 10 yards on each side
of the centre line in towns or villages.

The distances must be marked on the plan in miles and furlongs from
one of the termini.

The radius of every curve not exceeding one mile must be marked on the
plan in furlongs and chains.

In tunnels the centre line must be dotted, but no work must be shown
as tunnelling, in the making of which it is necessary to cut through,
or remove the surface soil. If it is intended to divert or alter any
public road, navigable river, canal, or railway, the course and extent
of such diversion, etc., shall be marked on the plan.

[Illustration: Fig. 2.]

When a railway is to form a junction with an existing railway, the          8
course of such existing railway must be shown on the plan for a
distance of 800 yards on each side of the proposed junction. In the
case of Bills for constructing subways, the plans and sections must
indicate the height and width of such subway, and the nature of the
approaches by which it is proposed to afford access to such subway.

The Book of Reference must contain the names of all owners, lessees,
and occupiers of all lands and houses of every parish within the
limits of deviation.

The numbers on the Book of Reference must correspond with the numbers
on the plan, and opposite to each number must be entered a brief
description of the property, whether field, garden, house, road,
railway, or river. It is intended that the plan and Book of Reference
together, shall afford ample information to enable all parties
interested to ascertain to what extent their property will be affected
by the proposed undertaking.

The section must be drawn to the same horizontal scale as the plan,
and to a vertical scale of not less than 100 feet to an inch, and must
show the level of the ground, the level of the proposed work, the
height of every embankment, the depth of every cutting, and a
horizontal datum line which shall be referred to some fixed point,
near one of the termini.

In every section of a railway, the line of railway marked thereon must
correspond with the upper surface of the rails.

Distances on the datum line must be marked in miles and furlongs to
correspond with those on the plan; a vertical measure from the datum
line to the line of the railway must be marked in feet and decimals at
the commencement and termination of the railway, and at each change of
gradient, and the rate of inclination between such vertical measures
must also be marked.

Wherever the line of railway crosses any public carriage road,
navigable river, canal, or railway, the height of the railway over, or
depth beneath the surface thereof, and the height and span of every
arch by which the railway will be carried over the same, must be
marked in figures.

[Illustration: Fig. 3.]

In the case of a public road level crossing, it must be described on
the section, and it must also be stated if such level will be
unaltered. If any alteration be intended in the level of any canal,
public road, or railway which will be crossed by the intended line of
railway, the same must be stated on the section and cross-sections to
a horizontal scale of not less than 330 feet to an inch, and a vertical    10
scale of not less than 40 feet to an inch must be added, which must
show the present surface of such road, canal, etc., and the intended
surface thereof when altered, and the greatest of the present and
intended rates of inclination marked in figures, such cross-sections
to extend 200 yards on each side of the centre line of railway.

Wherever the height of any embankment, or depth of any cutting, shall
exceed 5 feet, the extreme height over or depth beneath the surface of
the ground must be marked in figures upon the section.

All tunnels and viaducts must be shown on the section.

At a junction with an existing railway, the gradient of such existing
railway must be shown on the section on the same scale as the general
section for a distance of 800 yards on each side of the point of
junction.

Where the level of any turnpike or public road has to be altered in
making any railway, the gradient of any altered road need not be
better than the mean inclination of the existing road within a
distance of 250 yards of the point of crossing the railway; but where
the existing roads have easy gradients, then the gradients of the
altered roads, whether carried over, or under, or on the level with
the railway, must not be steeper than 1 in 30 for a turnpike road, 1
in 20 for a public carriage road, 1 in 16 for a private or occupation
road.

A good and sufficient fence, 4 feet high at least, shall be made on
each side of every bridge, and fences 3 feet high on the approaches.

The application to cross any public road on the level must be reported
upon by one of the officers of the Board of Trade, and special
permission for the work must be embodied in the Act.

Not more than 20 houses of the labouring classes may be purchased in
any city or parish in England, Scotland, and Wales, or more than 10
such houses in Ireland, until approval has been obtained to a scheme
for building such houses in lieu thereof as the authorities may deem
necessary.

Every bridge (unless specially authorized to be otherwise) must
conform with the following regulations:--

A bridge over a turnpike road must have a clear span of 35 feet on the
square between the abutments, with a headway, or height, of 16 feet
for a width of 12 feet, as shown on Fig. 12.

[Illustration: Fig. 4.]

A bridge over a public road must have a clear span of 25 feet on the       12
square between the abutments, with a headway of 15 feet for a width of
10 feet, as shown on Fig. 13.

A bridge over a private or occupation road must have a clear span of
12 feet on the square between the abutments, with a headway of 14 feet
for a width of 9 feet, as shown on Fig. 14.

Road bridges over the railway must have the same clear width between
the parapets, measured on the square, as the widths prescribed for
road bridges under the railway, or 35 feet for a turnpike road, 25
feet for a public road, and 12 feet for private or occupation road.

It is not compulsory, however, to construct the public road bridges
over or under the railway of a greater width than the average
available width of the existing roads within 50 yards of the point of
crossing the railway, but in no case must a bridge have a less width
than 20 feet. Should the narrow roads be widened at any future time,
the railway company will be under the obligation to widen the bridges
at their own expense to the extent of the statutory widths of 35 feet
for a turnpike road, and 25 feet for a public road.

Suitable accommodation works in the form of bridges, level crossings,
gates, or other works, must be provided for the owners, or occupiers
of lands, or properties intersected or affected by the construction of
the railway; or payments may be made by agreement instead of
accommodation works. All questions, or differences between the Railway
Company, and the owners or occupiers of property affected, will be
decided by the authorities duly appointed by the Government for the
purpose.

In constructing the railway, the Parliamentary plans and sections may
be deviated from to the following extent:--

The centre line may be deviated anywhere within the limits of
deviation (100 yards on each side of the centre line in country, and
10 yards each side in towns, or villages).

Curves may be sharpened up to half a mile radius, and further, if
authorized by the Board of Trade.

A tunnel may be made instead of a cutting, and a viaduct instead of an
embankment, if authorized by the Board of Trade.

The levels may be deviated from to the extent of 5 feet in the
country, and 2 feet in a town, or village, and various authorities
have power to consent to further deviations.

[Illustration: Fig. 5.]

Gradients may be diminished to any extent, gradients flatter than 1 in
100 may be made steeper to the extent of 10 feet in a mile, and            14
gradients steeper than 1 in 100 may be made steeper to the extent of 3
feet in a mile, or to such further extent as may be authorized by the
Board of Trade.

Suitable fences must be erected on each side of the line, to separate
the land taken for the use of the railway from the adjoining lands not
taken, and to protect such lands from trespass, or the cattle of the
owners, or occupiers thereof from straying on to the railway.

In addition to the Parliamentary plans, and sections, and Book of
Reference, an estimate of the cost of each separate line, or branch,
must be prepared as near to the following form as circumstances will
permit.

  ESTIMATE OF THE PROPOSED                    (RAILWAY).

  Line No._______
  ------------------------------------------+-----------------------------
                    Miles.     F.      Chs. |   Whether single or double.
  Length of Line:    ____     ____     ____ |   _______________________
  -----------------------+--------------+---+------+-----------+----------
                         | Cubic yards. | Price per | £ _s. d._ | £ _s. d._
                         |              |   yard.   |           |
                         +--------------+-----------+-----------+---------
  Earthworks:--          |              |           |           |
     Cuttings--Rock      |              |           |           |
               Soft soil |              |           |           |
               Roads     |              |           |           |
                         +--------------+-----------+-----------+
                   Total |              |           |           |
                         +--------------+-----------+-----------+
                                                                |
  Embankments, including roads, ____ cubic yards                |
  Bridges, public roads--number                                 |
  Accommodation bridges and works                               |
  Viaducts                                                      |
  Culverts and drains                                           |
  Metallings of roads and level crossings                       |
  Gatekeepers’ houses at level crossings                        |
  Permanent way, including fencing:--                           |
                                                                |
                 Miles.    F.   Chs.     |     Cost per mile.   |
                                         |    £    _s._  _d._   |
                  ____   ____   ____  at |   ____  ____  ____   |
                                                                |
  Permanent way for sidings, and cost of junctions              |
  Stations                                                      |
                                                                +---------
  Contingencies ____ per cent.                                  |
                                                                +---------
                       A.    R.    P.                           |
  Land and buildings  ____  ____  ____                          |
                                                                +---------
                                                      Total   £ |
                                                                +=========
  Dated this _______ day of ______________________ 18____

  Witness: __________________________

                                  ___________________________________
                                                            Engineer.

[Illustration: Fig. 6.]

The same details for each branch, and general summary of total cost.       16
Every Railway Bill must be read twice, both in the House of Commons
and in the House of Lords. A committee, duly appointed for each House,
must report upon it, and if the reports from such committees be
favourable, the Bill will be read a third time, and passed.

When it has passed both Houses, the Bill receives the Royal Assent,
and becomes law.

The minimum scale of four inches to a mile for the plans is so very
small that it is rarely, if ever, adopted. It would necessitate
enlarged plans of so many portions to show clearly the property or
buildings inside the limits of deviation, that in practice it is found
expedient to make the plans to a much larger scale.

Figs. 1 and 2 show a small portion of a Parliamentary plan and section
drawn to the minimum scale allowed, with an enlargement of a small
part to distinguish the houses clearly.

Figs. 3 and 4 show a part of the same plan and section drawn to a
scale of 400 feet to an inch, a scale which is very frequently
adopted, and is sufficiently large to distinguish the buildings and
small plots, except in closely populated districts. This scale also
gives ample room for reference numbers.

The Parliamentary plans and sections must be accurate in delineation,
levels, and description. All property within the prescribed limits of
deviation must be clearly shown, and the numbers and description on
the plans and book of reference must be concise and complete, to
enable the owners to ascertain to what extent they will be affected.
In every place where it is proposed to interfere with any public
highway, street, footpath, river or canal, the manner of such proposed
alteration must be shown and described on both plan and section. The
commencement and termination of every tunnel must be correctly
indicated, and the length given on both plan and section. An omission
of any of the above requirements might prove very detrimental to the
scheme, and possibly result in the Bill being thrown out of Parliament
for non-compliance with standing orders.

[Illustration: Fig. 7.]

In carrying out the works the constructors have power to deviate the
centre line either to the one side or the other, provided that such
deviation will permit of the boundary of the works, or property to be
acquired, to come within the limits of deviation or property               18
referenced, and they may also vary the levels of the line to the
extent prescribed in the standing orders.

Figs. 5 and 6 are parts of a Parliamentary plan and section showing
alteration of a public road with an overline bridge--also a diversion
of a small river to avoid two river bridges.

Figs. 7 and 8 are parts of a Parliamentary plan and section showing a
public road diverted and carried under the railway.

A stipulated time is fixed in the Bill for the purchase of the
property and construction of the line, and if this time be exceeded
before the completion of the works, it will be necessary to obtain
further Parliamentary powers for an extension of time.

Every new railway, or extension of railway, in the United Kingdom,
must be inspected, and certified, by one of the inspecting officers of
the Board of Trade, previous to Government sanction being granted for
its opening as a passenger line.

To facilitate these inspections, and as a guide both to their own
inspecting officers and the engineers in charge of the construction,
the Board of Trade have issued a list of the principal requirements in
connection with all new lines.

The following is a copy of the list so far as relates to works of
construction and signals:--


Requirements of the Board of Trade.--1. The requisite apparatus
for providing by means of the block telegraph system an adequate
interval of space between following trains, and, in the case of
junctions, between converging or crossing trains. In the case of
single lines worked by one engine under steam (or two or more coupled
together) carrying a staff, no such apparatus will be required.

2. Home-signals and distant-signals for each direction to be fixed at
stations and junctions, with extra signals for such dock, or bay
lines, as are used either for the arrival, or for the departure of
trains, and starting-signals for each direction, at all passenger
stations which are also block posts. On passenger lines all cross-over
roads and all connections for goods, or mineral lines, and sidings to
be protected by home and distant signals, and as a rule at all
important running junctions a separate distant-signal to be provided
in connection with each home-signal.

[Illustration: Fig. 8.]

_Signals may be dispensed with on single lines under the following
conditions_:--

(_a_) _At all stations and siding connections upon a line worked by        20
one engine only (or two engines coupled together), carrying a staff,
and when all points are locked by such staff._

(_b_) _At any intermediate siding connection upon a line worked under
the train staff and ticket system, or under the electric staff or tablet
system, where the points are locked by the staff or tablet._

(_c_) _At intermediate stations, which are not staff or tablet
stations, upon a line worked under the electric staff or tablet
system: Sidings, if any, being locked as in (b)._

3. The signals at junctions to be on separate posts, or on brackets;
and the signals at stations, when there is more than one arm on one
side of a post, to be made to apply--the first, or upper arm, to the
line on the left, the second arm to the line next in order from the
left, and so on; but in cases where the main, or more important line,
is not the one on the left, separate signal-posts to be provided, or
the arms to be on brackets. Distant-signals to be distinguished by
notches cut out of the ends of the arms, and to be controlled by home
or starting signals for the same direction when on the same post. A
distant-signal arm must not be placed above a home or starting signal
arm on the same post for trains going in the same direction.

In the case of sidings, a low short arm and a small signal light,
distinguishable from the arms or lights for the passenger lines, may
be employed, but in such cases disc signals are, as a rule,
preferable.

Every signal arm to be so weighted as to fly to and remain at danger
on the breaking at any point of the connection between the arm and the
lever working it.

4. On new lines worked independently, the front signal lights to be
green for “all right,” and red for “danger;” the back lights (visible
only when the signals are at “danger”) to be white.

_This requirement not to be obligatory in the case of new lines run
over by trains of other companies using a different system of
lights._

5. Facing points to be avoided as far as possible, but when they
cannot be dispensed with they must be placed as near as practicable to
the levers by which they are worked or bolted. The limit of distance
from levers working points to be 180 yards in the case of facing
points, and 300 yards in the case of trailing points on the main line,
or safety points of sidings.

[Illustration: Fig. 9.]

In order to ensure that the points are in their proper position before     22
the signals are lowered, and to prevent the signalman from shifting
them while a train is passing over them, all facing points must be
fitted with facing-point locks and locking-bars, and with means for
detecting any failure in the connections between the signal-cabin and
points. The length of the locking-bars to exceed the greatest
wheel-base between any two pairs of wheels of the vehicles in use on
the line, and the stock rails to be tied to gauge with iron or steel
ties. All points, whether facing or trailing, to be worked or bolted
by rods, and not by wires, and to be fitted with double
connecting-rods.

6. The levers by which points and signals are worked to be interlocked
and, as a rule, brought close together, into the position most
convenient for the person working them, in a signal-cabin or on a
properly constructed stage. The signal-cabin to be commodious, and to
be supplied with a clock, and with a separate block instrument for
signalling trains on each line of rails. The point-levers and
signal-levers to be so placed in the cabin that the signalman when
working them shall have the best possible view of the railway, and the
cabin itself to be so situated as to enable the signalman to see the
arms and the lights of the signals and the working of the points. The
back lights of the signal lamps to be made as small as possible,
having regard to efficiency, and when the front lights are visible to
the signalman in his cabin no back lights to be provided. The fixed
lights in the signal-cabin to be screened off, so as not to be
mistakable for the signals exhibited to control the running of trains.
If, from any unavoidable cause, the arm and light of any signal cannot
be seen by the signalman they must, as a rule, be repeated in the
cabin.

7. The interlocking to be so arranged that the signalman shall be
unable to lower a signal for the approach of a train until after he
has set the points in the proper position for it to pass; that it
shall not be possible for him to exhibit at the same moment any two
signals that can lead to a collision between two trains; and that,
after having lowered the signals to allow a train to pass, he shall
not be able to move any points connected with, or leading to, the line
on which the train is moving. Points also, if possible, to be so
interlocked as to avoid the risk of a collision.

[Illustration: Fig. 10.]

Home or starting signals next in advance of trading-points when            24
lowered, to lock such points in either position, unless such locking
will unduly interfere with the traffic.

A distant signal must not be capable of being lowered unless the home
and starting signals in advance of it have been lowered.

8. Sidings to be so arranged that shunting operations upon them shall
cause the least possible obstruction to the passenger lines.
Safety-points to be provided upon goods and mineral lines and sidings,
at their junctions with passenger lines, with the points closed
against the passenger lines and interlocked with the signals.

9. When a junction is situated near to a passenger station, the
platforms to be so arranged as to prevent, as far as possible, any
necessity for standing trains on the junction.

10. The junctions of all single lines to be, as a rule, formed as
double-line junctions.

11. The lines of railway leading to the passenger platforms to be
arranged so that the engines shall always be in front of the passenger
trains as they arrive at and depart from a station; and so that, in
the case of double lines, or of passing places on single lines, each
line shall have its own platform. At terminal stations a double line
of railway must not end as a single line.

12. Platforms to be continuous, and not less than 6 feet wide for
stations of small traffic, nor less than 12 feet wide for important
stations. The descents at the ends of the platforms to be by ramps,
and not by steps. Pillars for the support of roofs and other fixed
works not to be less than 6 feet from the edges of the platforms. The
height of the platforms above rail level to be 3 feet, save under
exceptional circumstances, and in no case less than 2 feet 6 inches.
The edges of the platforms to overhang not less than 12 inches. As
little space as possible to be left between the edges of the platforms
and those of the footboards on the carriages. Shelter to be provided
on every platform, and conveniences where necessary. Names of stations
to be shown on boards and on the platform lamps.

13. When stations are placed on, or near a viaduct, or bridge under
the railway, a parapet or fence on each side to be provided of
sufficient height to prevent passengers, who may by mistake leave the
carriages when not at the platform, from falling from the viaduct or
bridge in the dark.

[Illustration: Fig. 11.]

14. Footbridges or subways to be provided for passengers to cross the      26
railway at all exchange and other important stations. Staircases or
ramps leading to or from platforms to be at no point narrower than at
the top, and the available width to be in no case contracted by any
erection or fixed obstruction whatever below the top.

At all stations where crowding may be expected, the staircases or
ramps to be of ample width, and barriers for regulating the entrance
of the crowd at the top to be erected. If in such cases there are
gates at the bottom, a speaking-tube or other means of communication
between the top and bottom to be provided; and in all cases gates at
the bottom of a staircase or ramp to open outwards. For closing the
openings at the top, sliding bars or gates are considered best.

The steps of staircases to be never less than 11 inches in the tread,
nor more than 7 inches in the rise, and midway landings to be provided
where the height exceeds 10 feet.

Efficient handrails to be provided on both staircases and ramps, and
in subways where ramps are used the inclination not to exceed 1 in 8.

15. A clock to be provided at every station, in some conspicuous
position visible from the platforms.

16. No station to be constructed, and no siding to join a passenger
line, on a steeper gradient than 1 in 260, except where it is
unavoidable. When the line is double, and the gradient at a station or
siding-junction is necessarily steeper than 1 in 260, and when danger
is to be apprehended from vehicles running back, a catch-siding with
points weighted for the siding, or a throw-off switch, to be provided
to intercept runaway vehicles at a distance outside the home-signal
for the ascending line, greater than the length of the longest train
running upon the line.

Under similar circumstances, when the line is single, provision for
averting danger from runaway vehicles to be made--

  (1) At a station in one of the following manners:--

     (_a_) A second line to be laid down, a second platform to be
     constructed, and a catch-siding or throw-off switch to be
     provided on the ascending line inside the loop-points.

     (_b_) A loop-line to be constructed lower down the incline than
     the station platform with a similarly placed catch-siding or
     throw-off switch.

  (2) At a siding-junction in one of the following manners, except where   27
  it is possible to work the traffic with the engine at the lower end
  of a goods or mineral train, in which case an undertaking (see No.
  35) to do so, given by the company, will be accepted as sufficient:--

     (_a_) A similar loop to be constructed as in the case of a
     station.

     (_b_) Means to be provided for placing the whole train on sidings
     clear of the main line before any shunting operations are
     commenced.

17. Engine-turntables of sufficient diameter to enable the longest
engines and tenders in use on the line to be turned without being
uncoupled to be erected at terminal stations and at junctions and
other places at which the engines require to be turned, except in
cases of short lines not exceeding 15 miles in length, where the
stations are not at a greater distance than 3 miles apart, and the
railway company gives an undertaking (see No. 35) to stop all trains
at all stations. Care to be taken to keep all turntables at safe
distances from the adjacent lines of rails, so that engines, waggons,
or carriages, when being turned, may not foul other lines or endanger
the traffic upon them.

18. Cast-iron must not be used for railway under-bridges, except in
the form of arched-ribbed girders, where the material is in
compression.

In a cast-iron arched bridge, or in the cast-iron girders of an
over-bridge, the breaking weight of the girders not to be less than
three times the permanent load due to the weight of the
superstructure, added to six times the greatest moving load that can
be brought upon it.

In a wrought-iron or steel bridge, the greatest load which can be
brought upon it, added to the weight of the superstructure, not to
produce a greater strain per square inch on any part of the material
than five tons where wrought-iron is used, or six tons and a half
where steel is used.

The engineer responsible for any steel structure to forward to the
Board of Trade a certificate to the effect that the steel employed is
either cast-steel, or steel made by some process of fusion,
subsequently rolled or hammered, and of a quality possessing
considerable toughness and ductility, together with a statement of all
the tests to which it has been subjected.

19. In cases where bridges or viaducts are constructed wholly or           28
partially of timber, a sufficient factor of safety, depending on the
nature and quality of the timber, to be provided for.

_N.B.--The heaviest engines, boiler trucks, or travelling cranes in use
on railways afford a measure of the greatest moving loads to which a
bridge can be subjected. The above rules apply equally to the main
transverse girders and rail-bearers._

20. It is desirable that viaducts should, as far as possible, be
wholly constructed of brick or stone, and in such cases they must have
parapet walls on each side, not under 4 feet 6 inches in height above
the rail level, and not less than 18 inches thick.

Where it is not practicable to construct the viaducts of brick or
stone, and iron or steel girders are made use of, it is considered
best that in important viaducts the permanent way should be laid
between the main girders. In all cases substantial parapets, with a
height of not less than 4 feet 6 inches above rail-level must be
provided by an addition to the girders, unless the girders themselves
are sufficiently high. On important viaducts where the superstructure
is of iron, steel, or timber, substantial outside wheel-guards to be
fixed above the level of, and as close to the outer rails as possible,
but not so as to be liable to be struck by any part of an engine or
train running on the rails.

In the construction of the abutments or piers which support the
girders of high bridges and viaducts, cast-iron columns of small size
must not be used.

In all large structures a wind-pressure of 56 lbs. per square foot to
be assumed for the purpose of calculation, which will be based on the
rules laid down in the report, dated 30th May, 1881, of the committee
appointed by the Board of Trade to consider the question of
wind-pressure on railway structures.

21. The upper surfaces of the wooden platforms of bridges and viaducts
to be protected from fire.

22. All castings for use in railway structures to be, where
practicable, cast in a similar position to that which they are
intended to occupy when fixed.

23. The joints of rails to be secured by means of fish-plates, or by
some other equally secure fastening. On main lines, and lines where
heavy traffic may be worked at high speed, the chairs not to weigh
less than 40 lbs.; but on branch lines, or lines on which the traffic      29
is light, chairs weighing not less than 30 lbs. may be used.

24. When chairs are used to support the rails they must be secured to
the sleepers, at least partially, by iron spikes or bolts. With
flat-bottomed rails, when there are no chairs, or with bridge rails,
the fastenings at the joints, and at some intermediate places, to
consist of fang or other through-bolts; and such rails, on curves with
radii of 15 chains or less, to be tied to gauge by iron or steel ties
at suitable intervals.

25. In any curve where the radius is 10 chains or less, a check-rail
to be provided.

26. Diamond-crossings, as a rule, not to be flatter than 1 in 8.

27. No standing work (other than a passenger platform) to be nearer to
the side of the widest carriage in use on the line than 2 feet 4
inches, at any point between the level of 2 feet 6 inches above the
rails, and the level of the upper parts of the highest carriage doors.
This applies to all arches, abutments, piers, supports, girders,
tunnels, bridges, roofs, walls, posts, tanks, signals, fences, and
other works, and to all projections at the side of a railway
constructed to any gauge.

28. The intervals between adjacent lines of rails, where there are two
lines only, or between lines of rails and sidings, not to be less than
6 feet. Where additional running lines of rails are alongside the main
lines, an interval of not less than 9 feet 6 inches to be provided, if
possible, between such additional lines and the main lines.

29. At all level crossings of public roads, the gates to be so
constructed that they may be closed either across the railway, or
across the road at each side of the crossing, and a lodge, or, in the
case of a station, a gatekeeper’s box, to be provided, unless the
gates are worked from a signal cabin. The gates must not be capable of
being opened at the same time for the road and the railway, and must
be so hung as not to admit of being opened outwards towards the road.
Stops to be provided to keep the gates in position across the road or
railway. Wooden gates are considered preferable to iron gates, and
single gates on each side to double gates. Red discs, or targets, must
be fixed on the gates, with lamps for night use, and semaphore signals
in one or both directions interlocked with the gates, may be required.
At all level crossings of public roads or footpaths, a footbridge or a
subway may be required.

At occupation and field crossings, the gates must be kept hung so as       30
to open outwards from the line.

30. Sidings connected with the main lines near a public road level
crossing to be so placed that shunting may be carried on with as
little interference as possible with the level crossing; and, as a
rule, the points of the sidings to be not less than 100 yards from the
crossing.

31. At public road level crossings in or near populous places, the
lower portions of the gates to be either close barred, or covered with
wire netting.

32. Mile posts, half-mile, and quarter-mile posts, and gradient-boards
to be provided along the line.

33. Tunnels and long viaducts to be in all cases constructed with
refuges for the safety of platelayers. On under-bridges without
parapets, handrails to be provided. Viaducts of steel, iron, or timber
to be provided with manholes or other facilities for inspection.

34. Continuous brakes (in accordance with the Regulation of Railways
Act of 1889), complying with the following requirements, to be
provided on all trains carrying passengers, viz.--

     (1) The brake must be instantaneous in action, and capable of
     being applied by the engine-driver and guards.

     (2) The brake must be self-applying in the event of any failure
     in the continuity of its action.

     (3) The brake must be capable of being applied to every vehicle
     of the train, whether carrying passengers or not.

     (4) The brake must be in regular use in daily working.

     (5) The materials of the brake must be of a durable character,
     and easily maintained and kept in order.

35. Any undertaking furnished by a railway company to be under the
seal, and signed by the chairman and secretary of the company.


Recommendations as to the Working of Railways.--1. There should
be a brake vehicle, with a guard in it, at or near the tail of every
passenger train; this vehicle should be provided with a raised roof
and extended sides, glazed to the front and back, and it should be the
duty of the guard to keep a constant look-out from it along his train.

2. All passenger carriages should be provided with continuous
footboards, extending the whole length of each carriage and as far as      31
the outer ends of the buffer castings. As passenger carriages pass
from one company’s line to another’s, it is essential for the public
safety that, although the widths of the carriages on the different
lines may differ from each other, the widths across the carriages from
the outside of the continuous footboard on one side, to the outside of
the continuous footboard on the opposite side, should be identical for
the carriages of all railway companies, so that the lines of rails may
be laid at the proper distance from the edges of the passenger
platforms.

3. There should be efficient means of communication between the guard,
or guards, of every passenger train and the engine-driver, and between
the passengers and the servants of the company in charge of the train.

4. The tyres of all wheels should be so secured as to prevent them
from flying open when they are fractured.

5. The engines employed with passenger trains should be of a steady
description, with not less than six wheels, with the centre of gravity
in front of the driving-wheels, and with the motions balanced. They
should, as a rule, be run chimney in front.

6. Records should be carefully kept of the work performed by the
wearing parts of the rolling stock, to afford practical information in
regard to them, and to prevent them from being retained in use longer
than is desirable.

7. In addition to the block-telegraph instruments, it is desirable
that there should be speaking-instruments, or telephones, for
communication between signalmen, and books for recording the running
of the trains.

8. When drovers or other persons are permitted to travel with goods or
cattle trains, suitable vehicles should be provided for their
accommodation.

9. It is considered that, in fixed signals, the front lights should
show--

      Green, for all right;
      Red, for danger;

and that back lights, visible only when the signals are at danger,
should show white.

10. Refuge sidings should be provided at all main-line stations where
slow trains are liable to be shunted for fast trains to pass them. If
at such stations it is impossible to provide refuge sidings, and slow      32
trains have to be shunted from one main line to the other to allow of
fast trains passing them, some simple arrangements should be supplied
in the signal cabins to help to remind the signalman of the shunted
train.

11. Efficient means should be adopted to prevent the accidental
opening of the doors of passenger trains.

       *     *     *     *     *

To carry out the undertaking, the engineer has to prepare working
plans and sections to a somewhat larger scale than that adopted for
the Government or Parliamentary plans, and on which must be marked the
exact positions of the commencement of the curves, straight lines, and
gradients. The sites of all the over and under bridges must be shown,
and their angles of crossing noted. All road, river, or stream
diversions must be indicated, so that the work in connection with them
may be laid out on the ground. All culverts and drains must be marked,
and their size, depth, and direction described. Public road
level-crossings, and farm or occupation-road crossings, must be shown
in their proper positions.

The face-lines of the ends of all tunnels should be marked on the
working plan and section, and the position of any shafts, which may be
intended either for use in carrying on the work or for future
ventilation.

A considerable amount of investigation and negotiation will have to be
entered into before the locating of the above works can be finally
decided. The desire to meet the wishes and convenience of all parties
interested must of necessity be controlled by the physical
circumstances of each case; very little alteration can be made in the
level of the rails, although some variation may be made in their
position.

When fixing the depths of culverts and drains, attention must be paid
to any probable improvement in the drainage of the district, which
might at some future time necessitate the deepening of such of the
main culverts where the inverts had been laid too high.

Unless all these details are determined, and shown on the
working-plans before the works are commenced, there is the risk that
embankments may have to be opened out to admit of bridges and
culverts, and cuttings changed to permit of road diversions.

The entire centre-line of railway must be carefully staked out by          33
driving strong wooden pegs into the ground at the end of every chain
length, and along the course of these pegs the longitudinal section
must be taken. Three pegs, one on each side of the centre peg, are
generally placed at the commencement and termination of the curves.
When the longitudinal section has been plotted to scale, and the
course of the gradients and level portions worked out and drawn on,
then the heights of the ground level and formation level can be marked
at each chain, and from them the depths of the cutting and the heights
of the embankments can be ascertained and marked at each chain. In
addition to the longitudinal section, it will be necessary to take a
large number of transverse or cross sections at those pegs, or
intermediate points, where the ground is at all side-lying or
irregular. These cross-sections are necessary to determine the
side-widths, or distances to outer edge of slopes in cuttings or
embankments, and also to calculate the actual quantity of earthwork to
be executed. For convenience in taking out the quantities, these
cross-sections are generally plotted to a natural scale, that is to
say, to the same scale horizontal as vertical, as shown in the example
of cross-sections, Figs. 15 to 24. It is also necessary to obtain
information, by boring or otherwise, as to the material of which the
cuttings are composed, whether clay, gravel, or rock.

In laying out lines through fairly level plains and populous
districts, the absence of great natural obstacles will allow the
engineer to carefully consider how far it may be prudent to diverge to
the right or to the left, to accommodate towns and places which would
be excluded by a more direct through route. There will be ample range
for selection, and it will be rather the question of policy than
compulsion which will guide him in the route to be taken.

[Illustration: Fig. 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]

When, however, the locating passes from the lower ground, away up
amongst the hills and mountain ranges, it becomes an intricate study
whether it will be possible to lay out any line at all which may
possess gradients and curves practicable for railway working. The
question of property, population, or convenience of access, is here no
longer the controlling influence, but in its stead there are the far
more formidable natural difficulties to be overcome in working out a
trackway to the inevitable summit level. The chief endeavour will be
to gain length, and so reduce as much as possible the steepness of the
gradients which at the best must necessarily be severe. In some of the     35
earlier mountain lines constructed abroad the system of _zigzags_ was
introduced, as shown in Fig. 25. These _zigzags_ were laid out on
ruling gradients, one above the other, on the sides of the mountain
slopes with pieces of level at the apices, A, B, and C, on which
the engine could be changed from one end of the train to the other.
Although feasible in principle, the system entailed considerable loss
of time in train-working, and was not unattended with risk.

The more modern and simple method of working out the same idea is to
connect the main zigzag lines by curves or _spirals_, thus rendering
the route continuous and unbroken. By this arrangement the heavy work
and delay in starting or stopping the train at the apices, A, B,
and C, as shown on Fig. 25, is avoided, and the train can proceed
continuously on its circuitous journey. Fig. 26 shows an instance of
the zigzags and spirals, as carried out on an important railway
abroad. To have made a direct line from D to E, the most difficult
part of the route, would have involved a gradient of 1 in 11; but by
constructing the spiral course, as shown, the length was more than
trebled, and the gradient reduced to 1 in 35.

Fig. 27 is another example of spiral zigzags in which advantage was
taken to cut a short tunnel through a high narrow neck of rock at
G, and then by skirting round the hill the line was taken over the
top of the tunnel and along the side of the mountain to the summit tunnel
at H. By this means the line from F to H was laid out to an
average gradient of 1 in 42.

Fig. 28 shows the Cumbres inclines on the Mexican Railway. The route
had to be located through one of the rugged passes of the great Chain
of the Andes, whose mountain-sides rise most abruptly from the lower
plains, to the great upper-land plateau, some eight thousand feet
above sea-level. The ground to be traversed was so steep and difficult
that, even with the best available detours and greatest length that
could be obtained, the result was an average continuous gradient of 1
in 25 for 12 miles.

[Illustration: Fig. 25, 26, 27, 28, 29]

Fig. 29 is a plan of part of the St. Gothard Railway, showing the
principal tunnel 9¼ miles long, and some of the adjoining spiral
tunnels. The long tunnel through the great Alpine barrier was the only
means of forming a railway connection between the two points at Airolo
and Goeschenen. Constructed in a straight line, with easy gradients,       37
falling towards the entrances, efficiency of drainage has been
secured, and excessive strain on motive-power avoided. The approaching
valleys on each side were in some places too irregular and broken to
admit of zigzag loops, and the spiral tunnels were adopted instead.
The enlarged plan of two of the spiral tunnels will explain the method
of working. An ascending train enters the first tunnel at A, and
after passing round almost an entire circle, on a rising gradient,
emerges at a much higher level at the point B. Proceeding onward,
the train enters the second tunnel at C, and after passing round a
similar circle, on a rising gradient, comes out at a still higher
point, D, and continues its course up the valley.

The last five sketches illustrate some of the methods which have been
adopted when constructing railways through some of the most difficult
mountain ranges. They show what has been done, and may serve as guides
in working out the location of a line in some hitherto unexplored
region.


Gauge.--The gauge of a railway, or its width from inside to inside
of rails, affects both its cost and efficiency. If the gauge be
exceptionally wide, then the expenditure on works and rolling-stock
will be proportionately heavy; and although theoretically the extra
wide gauge may possess greater capabilities for accommodation and
high-speed travelling, we may find in practice that the necessary
requirements may be provided on a much more moderate gauge. On the
other hand, if the gauge be exceptionally narrow, there will be
diminished convenience both for passengers and merchandise, and a
corresponding limit to the speed in transit.

In isolated districts, where passenger traffic is of secondary
importance, and where the principal merchandise will be heavy without
being bulky, such as mineral ores, slates, etc., a comparative narrow
gauge may possibly suit the purpose. For main trunk lines, however,
where a large, heavy, and fast passenger traffic will have to be
worked, and where goods of all kinds, many of them bulky without being
heavy, will have to be carried, an ample gauge must be selected to
ensure convenience and safety. A liberal gauge permits the use of
commodious rolling-stock without any great amount of lateral
overhanging weight outside the wheels; whereas with a narrow gauge
there is the tendency--if not the necessity--to use vehicles which have
too great a lateral overhang for proper stability, except at very          38
moderate speeds.

The following list shows the gauges adopted in various countries:--

                     ft. ins.
  England, Scotland,
    and Wales        4   8½
  Ireland            5   3
  United States      4   8½, with some lines 5 ft., 5 ft. 6 ins., and 6 ft.
  Canada             4   8½  and 5 ft. 6 ins.
  France             4   8½
  Belgium            4   8½
  Holland            4   8½
  Germany            4   8½
  Austria            4   8½
  Switzerland        4   8½
  Italy              4   8½
  Turkey             4   8½
  Hungary            4   8½
  Denmark            4   8½
  Norway             4   8½ and 3 ft. 6 ins.
  Sweden             4   8½
  Mexico             4   8½ and 3 ft.
  Egypt              4   8½ and 3 ft. 6 ins.
  Peru               4   8½
  Nova Scotia        4   8½ and 5 ft. 6 ins.
  New South Wales    4   8½
  Brazil             4   8½, 5 ft. 3 ins., and 5 ft. 6 ins.
  Uruguay Republic   4   8½
  Russia             5   0
  South Australia    5   3
  New Zealand        3   6
  British India      5   6 and 1 metre.
  Ceylon             5   6
  Spain              5   6
  Portugal           5   6
  Chili              5   6
  Argentine Republic 5   6
  Cape Colonies      3   6
  Japan              3   6

After many years’ experience of actual working, the broad, 7 feet,
gauge of the Great Western Railway has been abandoned for the 4 feet
8½ inch gauge. Doubtless this decision was the result of most careful
deliberation, and was made upon convincing proof that the 4 feet 8½
inch gauge could fulfil all the advantages claimed for the wider
gauge, whilst at the same time it possessed the merit of less cost of
construction and working, and greater facilities for the exchange of
traffic with other lines having the standard gauge. The facility of
exchange, or through working of rolling-stock, is a leading element of
successful railway working, and it is difficult to estimate what would
be the amount of loss and delay if we had any great extent of break of
gauge on the main trunk lines of our own country.

Although some countries have selected gauges of 5 feet and 5 feet          39
6 inches, it is interesting to note that the largest number have
adopted the English standard gauge of 4 feet 8½ inches, and that the
miles of line laid to this gauge far outnumber all the others. The
fact that our own home lines, the principal Continental lines, and
nearly all that vast network of railways in the United States of
America, have been laid to the 4 feet 8½ inch gauge, testifies to the
general opinion of its utility and efficiency; and we know that
included in that list are the railways which carry the largest,
heaviest, and fastest train service in the world.

It would be interesting to trace back, and, if possible, ascertain
from whence the exact gauge of 4 feet 8½ inches was derived. No doubt,
in the early days of the pioneer iron highways in England, the
railways were made the same gauge as the tramroads which they
superseded. But why was 4 feet 8½ inches the gauge of the tramroads?
We may reasonably infer that the first four-wheeled waggons used on
the early tramroads were in reality the same waggons which had been
previously used on the common roads for the conveyance of coal and
minerals to the ports for shipment, and that the waggons were merely
transferred from the roughly paved or macadamised roads to the
tramroads. Flanged wheels were then unknown, and the introduction of
the tram-plates was at first simply designed to lessen the resistance
to haulage. The gauge, or width between the wheels, of these waggons
may have been the outcome of long experience as to the most suitable
width for convenience of load, stability during transit, or for space
occupied on the highway. The width may have been handed down from
generation to generation, going back to the time when wheeled vehicles
were first built in the country. Perhaps in the beginning the first
vehicles may have been imported from Italy, or Greece--countries which
in the earlier ages were the most advanced in matters of luxury and
convenience.

When in Pompeii, a few years ago, the writer measured the spaces
between a large number of the _wheel-ruts_ which are worn deep
into the paving-stones in many of the principal streets of that
wonderful unearthed city. These paving-stones, very irregular in
shape, and many of them 2 feet 6 inches long by 1 foot 6 inches wide,
are carefully fitted together, and form a compact massive pavement
from curbstone to curbstone. The wheel-tracks, which are in many
places worn into the stones to the depth of an inch or an inch and a       40
half, are always distinct, and there is no difficulty in defining the
corresponding track.

The result of a large number of measurements gave an average width of
about 4 feet 11 inches from centre to centre of the wheel-tracks, a
curious coincidence with the gauge of our own road vehicles at the
beginning of the railway era. Whether our selection of the railway
gauge of 4 feet 8½ inches has been the result of study, imitation, or
caprice, we certainly have the silent testimony of these old deep-worn
stones to prove that two thousand years ago the chariots of Pompeii
were of very similar gauge to our own of modern times.

Narrow-gauge railways, of gauges varying from 1 foot 10½ inches on the
Festiniog Railway, to 3 feet, 3 feet 3 inches (metre), and 3 feet 6
inches, have been made in several places both at home and abroad.
Generally speaking, they have been constructed as subsidiary or
auxiliary lines in thinly populated districts, with a view to afford
some railway accommodation where it was considered that lines of the
standard gauge would not pay. In some instances abroad long lines of
narrow gauge--3 feet and 3 feet 6 inches--have been constructed as
main trunk lines in newly opened out districts. Some of these have
since been altered to a wider gauge as the traffic developed, and
experience proved that the narrow width of the vehicles was unsuitable
for quick transit, or convenience in the accommodation of passengers
and goods.

The object in making a line to a narrow gauge is doubtless to save
cost in the original construction; but when a scheme for an altered
gauge is put forward, it will be well to consider what amount of
advantage or saving would be effected by deviating from the standard
gauge.

If there be almost a certainty that such proposed line will always
remain isolated from all other existing railways of the standard
gauge, then perhaps the selection of gauge may be one of minor
importance, and there remains but the question whether the description
of traffic, and the weights to be carried, can be worked to any
greater advantage, or more economically, by deviating from the
standard gauge.

If, however, there be a fair probability that such proposed line may
at some future time become part of an already established railway
system, it would appear to be more prudent to make the line to the
standard gauge, and effect economies by introducing steeper gradients,     41
sharper curves, and lighter permanent way, and keep down working
expenses by using lighter locomotives, worked at slower speeds.

High speeds are not expected on narrow gauge railways, and no
complaints are made about passenger trains whose highest running speed
does not exceed 20 miles per hour. By conceding the same indulgence to
light railways made to the standard gauge, great economies might be
introduced both in their construction and working. The similarity of
gauge would admit the transit of the carriages and waggons of other
standard gauge lines, and so avoid all cost and delay in transshipment.
The heavy engines could be kept for the main-line working, and light
engines for slow speeds would serve for the light standard-gauge
lines. As traffic developed, and the train service required heavier
and faster trains, the light rails could be removed, and replaced by
those of heavier section to correspond to the main line. The
similarity of gauge would permit uninterrupted transit of all vehicles
to a common centre for repairs, whereas the narrow gauge carriages and
waggons, being limited to running only on their own district, must
have separate workshops for their repair.

When considering the cost of construction and working of a
narrow-gauge railway as compared with one of the standard gauge, there
are certain items which are common to both, and in which the narrow
gauge could not be expected to obtain any advantage over the standard
gauge.

There would not be any saving in getting up the scheme in the first
instance;

  Nor in the Parliamentary expenses;
  Nor in the engineering or carrying out of the works;
  Nor in the station accommodation, waiting-rooms, and offices;
  Nor in the signals and interlocking arrangements;
  Nor in the telegraph;
  Nor in the working staff and train men;

Nor in the maintenance of the permanent way, as the same number of men
would be required for the inspection and packing of the road, perhaps
more.

Little or no saving could be expected in the bridges under the
railway, as these must be made to the prescribed widths and heights,
irrespective of the gauge of the railways.

Little, if any, saving could be made in river or stream bridges, as the    42
same amount of waterway would have to be provided in each case.

The same remark applies to culverts and drains.

There would, on the other hand, be a small saving in the quantity of
land to be acquired to the extent of a narrow strip or zone,
represented by the difference in width between the narrow and standard
gauges.

There would also be the same small proportionate saving in the
embankments and cuttings to the extent of the difference in gauge.

Also a saving in the overline bridges and road approaches in
consequence of less width and height of the opening through those
bridges.

And a saving in the rails, sleepers, and ballast of the permanent way,
to the extent consistent with efficiency. That some saving may be
effected in these is undoubted, but it is necessary to exercise
caution, and not rush to the opposite extreme by making the parts too
light. A rail should be made not only strong enough to carry well the
engines that have to pass over it, but it should also be heavy enough
to stand the wear of several years. Narrow-gauge engines must be heavy
in conformity with the loads they have to haul. The same amount of
power must be exerted to haul a hundred tons on a given gradient,
whether the gauge be narrow or broad. In some cases of narrow-gauge
railways the original rails, which weighed only 45 lbs. per yard, have
since been replaced with others weighing 60 and 65 lbs. per yard. The
light 45 lb. rails were evidently not found to be sufficiently heavy
to keep the road to proper line and level. The result of our everyday
practice seems to prove that there is not only an advantage, but an
economy, in adopting rails of a heavy section, and experience would
therefore indicate that even for a narrow-gauge railway it may not be
expedient to adopt rails weighing less than 65 lbs. per yard.


Gradients.--There are very few localities where the rails on any
line of railway can be laid perfectly level or horizontal for more
than comparatively short distances. By far the greater portion have to
be laid on inclined planes of varying rates of inclination to suit the
general formation of the district traversed, and the circumstances of
the line to be constructed.

The degree, or rate of inclination, of these inclined planes, or
gradients, may be expressed in various ways. A very general method is      43
to state the number of feet, metres, etc., which can be measured along
the gradient before an increased rise or fall of one foot or metre,
etc., is obtained. Thus a gradient of 1 in 200 signifies a rise or
fall of 1 foot in 200 feet, or 1 metre in 200 metres.

Sometimes the rate of inclination is expressed by stating the number
of feet of rise or fall in a mile. In this way a gradient would be
described as falling at the rate of 30 feet in a mile, rising at the
rate of 20 feet in a mile, etc. Twenty feet to a mile is equal to 1 in
264.

Another method is to give the percentage of rise or fall. In this way
the inclination would be expressed as a 1 per cent. gradient, 2 per
cent. gradient, ½ per cent. gradient, etc., which for comparison would
signify 1 in 100, 1 in 50, and 1 in 200 respectively.

The gradients of a railway most materially influence its facility and
cost of working, and every effort should be used to make them as easy
as possible consistent with the prospect of the line.

Steep gradients signify heavy locomotives, increased cost of
motive-power, reduced speed, and light loads.

The following tabulated memoranda show the approximate loads,
exclusive of engine and tender, which can be hauled on the level and
on certain inclines at various speeds by engines of the quoted
capacities and steam admissions. A medium-sized, ordinary type of
passenger and goods engine has been selected for each of the examples.
The working of the passenger engine and train is assumed to be under
favourable circumstances, with fine weather, fairly straight line,
first-class permanent way, modern rolling-stock with oil axle-boxes
and perfect lubrication, and all the conditions most suitable to
ensure the least resistance to the moving load. For the goods engine
and train a greater resistance per ton of load is assumed, as the
goods trucks are never so perfect or easy in the running as the
passenger carriages. A certain amount of side wind is taken into
consideration, and also an allowance for moderately sharp curves, the
object being to indicate what may be looked upon as fair, average,
workable loads.

The loads for engines of larger or smaller dimensions, or higher or
lower pressures, may be obtained by working out the proportion between     44
the tractive force put down in any of the columns of the tabulated
memoranda and the ascertained tractive force of any other engine under
the same conditions of cut-off and speed.

  -----------------------+-------------------------+-------------------------
                         |   PASSENGER ENGINE.     |      GOODS ENGINE.
                         |                         |
                         |Six wheels, driving      |Six wheels, all coupled,
                         | and trailing wheels     | 4 ft. 6 ins. diameter.
                         | coupled, 6 ft. 6 ins.   | Cylinders,
                         | diameter. Cylinders,    | 17 ft. × 24 ft.
                         | 17 ft. × 24 ft.         | Locked-down pressure on
                         | Locked-down pressure on | safety-valves, 140 lbs.
                         | safety-valves, 140 lbs. | per square inch. Assumed
                         | per square inch. Assumed| pressure at cylinders,
                         | pressure at cylinders,  | 120 lbs. per square inch.
                         | 120 lbs. per square     |
                         | inch.                   |
                         |                         |
                         |Weight of engine 39 tons.|Weight of engine 34 tons.
                         |  ”       tender 24  ”   |  ”       tender 24  ”
                         |                 --      |                 --
                         |                 63  ”   |                 58  ”
  -----------------------+-----+-----+------+------+-----+-----+------+------
  Assumed cut-off        |  ¼  |  ⅓  |  ½   |  ¾   |  ¼  |  ⅓ |   ½  | ¾
      ”   mean effective |     |     |      |      |     |     |      |
           pressure, lbs.|  45 |  56 |  76  | 100  |  45 |  56 |  76  | 100
      ”   tractive force,|     |     |      |      |     |     |      |
           lbs.          | 4000| 4979| 6758 | 8892 | 5780| 7192| 9760 | 12844
  Speed in miles per hour|  60 |  40 |  30  |  15  |  40 |  30 |  20  |  15
                         |     |     |      |      |     |     |      |
                         |Tons.|Tons.|Tons. |Tons. |Tons.|Tons.|Tons. |Tons.
                         |     |     |      |      |     |     |      |
  Level                  |  97 | 230 | 447  | 892  | 213 | 358 | 623  | 907
  1 in 1000              |  84 | 196 | 373  | 707  | 187 | 310 | 532  | 768
    ”   800              |  81 | 188 | 358  | 671  | 181 | 299 | 512  | 739
    ”   600              |  76 | 177 | 335  | 618  | 172 | 285 | 482  | 695
    ”   400              |  68 | 157 | 296  | 533  | 157 | 257 | 432  | 621
    ”   300              |  60 | 141 | 263  | 467  | 143 | 233 | 390  | 560
    ”   250              |  55 | 129 | 241  | 424  | 133 | 216 | 361  | 519
    ”   200              |  47 | 114 | 213  | 372  | 120 | 195 | 324  | 467
    ”   150              |  37 |  93 | 177  | 304  | 101 | 165 | 276  | 397
    ”   100              |  21 |  63 | 126  | 217  |  74 | 123 | 208  | 302
    ”    90              |  -- |  56 | 114  | 197  |  -- | 113 | 191  | 279
    ”    80              |  -- |  48 | 101  | 175  |  -- | 101 | 172  | 253
    ”    75              |  -- |  43 |  94  | 164  |  -- |  95 | 163  | 240
    ”    70              |  -- |  39 |  86  | 152  |  -- |  88 | 153  | 226
    ”    60              |  -- |  28 |  70  | 128  |  -- |  74 | 131  | 196
    ”    50              |  -- |  -- |  53  | 101  |  -- |  -- | 107  | 163
    ”    40              |  -- |  -- |  --  |  73  |  -- |  -- |  --  | 127
    ”    25              |  -- |  -- |  --  |  27  |  -- |  -- |  --  |  67
  -----------------------+-----+-----+------+------+-----+-----+------+------

  NOTE.--The column loads in tons are exclusive of the weight of
         engine and tender.

From the above memoranda it will be seen how greatly the gradients         45
affect the loads. For an important main trunk line, with a heavy and
frequent train-service of passengers and goods, the introduction of
steep gradients would not only reduce the speed of the train-working,
but would probably involve the necessity of assistant engines over
those parts of the line; and it may be prudent, where possible, to
incur heavier earthworks, or considerable detours, or tunnels, to
obtain more favourable gradients. For such a line the additional cost,
and the extra distance caused by a detour of a mile or more, will be
of far less importance than the interruption in the train service
arising from a serious reduction in speed or taking on assistant
engines. On many railways abroad there are very interesting examples
of long detours of several miles, carefully studied out to obtain
greater length and easier gradients, resulting in the construction of
lines over which the traffic can be worked without necessitating
auxiliary engine-power. On the other hand, there are situations where
steep gradients cannot be avoided, where certain altitudes must be
reached, and where there is no alternative but to face the inevitable.

On secondary lines, and short branch lines, where the traffic is not
expected to be heavy, and where speed is not so important, it may be
policy to economize outlay and introduce steeper
gradients than on the main line.

Half a mile of a rather steep gradient is not felt so much when it is
situate midway between two stations, because the attained speed of the
train assists the engine over the short distance to the summit; but
when it occurs as a rising gradient out of a station, it forms a great
check to the working, particularly in bad or wet weather, when there
is the risk of the engine slipping, and the entire train sliding back
into the station.

Long steep gradients not only necessitate increased motive-power for
the ascending trains, but also require increased brake-power, and
precautionary measures for the descending trains. Where passenger
trains are fitted with continuous brakes, the risk of losing control
is minimized; but with goods trains composed of waggons, having only
the ordinary independent side-lever brake, it will be found absolutely
necessary in many cases to have additional heavy brake-vans for
descending the inclines, and these special vans, unfortunately, will
form so much extra non-paying weight to be hauled up on the ascending
trains. Of course, it is quite possible--and, indeed, in many places       46
it is customary--to pin down some of the side-lever brakes before
commencing the descent, but once pinned down the brakes cannot be
eased or taken off until the entire train is brought to a stand.

Every goods waggon should be fitted with a brake, and it would be of
immense value if that brake could in all cases be applied and
controlled when the train is in motion.

The American type of long goods waggon, with a four-wheel bogie-truck
at each end, is fitted with a brake very similar to those adopted on
the ordinary horse tram-cars. On the top of the waggon a horizontal
iron hand-wheel, about 18 inches in diameter, is fixed on to a strong
vertical iron rod, which works in brackets, and extends down below the
underside of waggon framing. One end of a short length of chain is
secured to the foot of the vertical rod, and the other end is
connected by light iron rods to the series of levers which pull on the
brake-blocks. By rotating the horizontal hand-wheel the chain is
coiled round the lower end of the vertical rod, the brake-levers are
pulled over, and brake-pressure applied to the wheels of the waggon.
The brakesman is supplied with a convenient seat and footboard, and on
the floor-level of the latter there is a pawl and ratchet attached to
the vertical rod, which permits the brakes to be applied to the extent
required. The pawl retains the brakes in position until the brakesman
with his foot pushes the pawl out of the notch of the rachet and
releases the brake gearing, which is at once pulled off quite clear by
strong bow-strings attached to the framework of the bogies.

This type of hand-brake is, perhaps, the simplest that can be made.
The brakesman has merely to put it on, the pawl and ratchet keep it
on, and the bow springs take it off when no longer required. Each one
of these long, loaded goods waggons becomes a very serviceable
brake-van, and for ascending and descending steep inclines all that is
necessary is to take on a few additional brakesmen to manage the
brakes of as many suitable waggons. These incline brakesmen, after
going down, can return to the summit by the next ascending train,
their small weight being a mere nothing as compared with that of
special or extra brake-vans.

On some European lines it is the custom to sprag some of the goods
waggon wheels when going down exceptionally steep inclines, as well as     47
applying the brakes on the ordinary and extra brake-vans. The sprag is
a piece of wood, circular in section, about 2 feet 6 inches long, and
5 to 6 inches thick in the middle, tapering off to about 2 inches
thick at the ends. When the waggon-wheel is just beginning to move,
the sprag is inserted between the spokes, and being caught against the
waggon framework, the wheel is held fast, and being unable to revolve,
remains fixed, and acts like a skid upon the rails. The skidding of
the wheels upon the rails wears flat places on the wheel tyres, and it
is needless to mention that the practice is only resorted to in very
extreme cases. Although a very primitive means for checking the speed
of a descending train, or for maintaining vehicles stationary on an
incline, there have been many instances where lives have been saved
and accidents prevented by the prompt use of a few sprags. Solid or
close wheels cannot be spragged, only wheels which have spokes or
openings, and for this reason alone it would be very desirable that in
every passenger and goods train there should be some spoke or open
wheels which could be spragged as a last resource, in the event of a
sudden emergency of brakes failing or train becoming divided on an
incline.

On ascending gradients there is always the risk of a coupling
breaking, and the train becoming divided. If the detached portion left
behind be provided with ample brake-power, hand-brakes, or otherwise,
no harm may take place beyond a little delay; but if the brake-power
be insufficient or defective, and if all the wheels are solid wheels
incapable of admitting a few timely sprags, then the vehicles cannot
be held, but must slide back, and running unchecked would soon attain
such a velocity as would cause them either to leave the rails or dash
into another train standing at the last station. Many lamentable
accidents have taken place arising from portions of trains breaking
away and running back, and the sad experience of those casualties
should call forth every effort to avert a recurrence in the future. It
may not always be possible to detect a hidden flaw in a coupling, or a
defect in the brake-gearing until the actual failure occurs; but it is
quite possible to guard against disastrous results from such failure,
by providing means to hold the vehicles, and prevent them sliding
back.

For some years the writer had the entire charge of an important
railway abroad on which the gradients were very exceptional, and where     48
it was absolutely necessary that he should organize the most complete
precautions to prevent the possibility of trains, or portions of
trains, running back down inclines. Starting from sea-level, the line,
which was laid to the 4 feet 8½ inch gauge, rose to a summit of over
8000 feet, and on the mountain division there were many long gradients
of 1 in 40, 1 in 33, and in one place a continuous gradient of 1 in 25
for 12 miles. The specially powerful engines reserved for these heavy
inclines were each supplied with an ordinary hand-brake, a
steam-brake, and a Westinghouse continuous brake. The passenger
carriages, which were of considerable length, and carried on a
four-wheeled bogie-truck at each end, were all fitted up with the
Westinghouse brake, and in addition each carriage had its own
hand-wheel brake with the pawl and ratchet gearing. All the goods
waggons, which were of the American type, were fitted with hand-wheel
brakes similar to those on the carriages. Special gangs of trained
brakesmen took charge of the trains on these inclines, a brakesman to
every carriage or waggon, and were always in readiness in case of the
breakage of a coupling, or the failure in the Westinghouse brake or
brakes on engine. The immunity from accidents justified the combined
precautions adopted, and proved the possibility of working such severe
gradients with perfect safety.

The long-continued application of the brakes on heavy inclines
naturally leads to the question as to the description of wheel to be
adopted for the work. Not only are the wheels subjected to very severe
torsional strains, but the temperature at the circumference is raised
very high in consequence of the friction. Perhaps, theoretically, the
safest wheel would be one made out of a solid piece of metal, similar
to the chilled cast-iron wheels of the United States, or the steel
disc wheels used on some lines in Europe, in either of which holes can
be left for sprags. Wheels of this description can withstand very
heavy wear and tear, they are not affected by increased temperature,
and they certainly have the minimum of parts to work loose. Of the
built-up wheels, the strong forged-iron-spoke wheel with steel tyres
shows excellent results, and always gives due warning of loosening by
indications at the tyre rivets. The suddenness with which the solid
wooden centre wheels sometimes break up and fall to pieces does not
commend them for a service where there must be a long-sustained
application of the brakes. The increased temperature which expands the     49
tyre, contracts the wood, and must loosen and weaken the entire wheel.

On all steep gradients the road-bed should be of the most substantial
character, and the permanent way of a strong description, and
maintained in perfect order, as the engines for working the traffic
must necessarily be of a heavy type. The rails will be severely tested
by the pounding and slipping of the engines on the ascending journey,
and by the action of the brakes on the descending journey.

In the early days of the railway system, rope-haulage was adopted on
some of the main lines for working the trains on steep inclines near
the principal terminal stations. A powerful stationary engine, located
at the highest point, was employed to work an endless rope which
passed round large drums at the top and bottom of the incline, and was
supported on sheaves or pulleys fixed between the rails. The
connection between the carriages and endless rope was effected by
means of a short piece of rope called the _messenger_, which was
coiled round the main rope in such a manner as to be readily detached
when the train reached the summit. There are many persons who will
remember the time when the passenger trains were hauled by an endless
rope up the 1 in 66 incline from Euston to Camden Town, a distance of
about a mile and a half, and up the 1 in 48 incline from Lime Street,
Liverpool, to Edge Hill, a distance of about a mile and a quarter, and
several others. The rapid strides made in locomotive construction, and
the increased pressure used in the boilers, enabled much more powerful
engines to be built, until one by one the rope-haulage machinery has
disappeared from nearly all the inclines where for years it had been
considered indispensable. Rope-haulage on inclines is now very rarely
met with, except at collieries and ironworks, where occasionally the
rope may be seen so arranged that the loaded waggons descending pull
up the empty waggons on the opposite or parallel line.


Curves.--The degree of curvature of a railway curve is generally
expressed by giving the radius in feet, chains, metres, or other
national standard measure.

When laying out a line of railway, the natural features of the country
will necessitate the introduction of curves, and the question for
consideration will be whether they are to be made of small or large
radius. In some cases sharp curves are inevitable, except by incurring     50
enormous works which would not appear to offer any corresponding
prospective recompense. In others the curves may be made of easy
radius, at a comparative moderate extra outlay, if the character of
the line and description of traffic to be accommodated will warrant
the expenditure. For main through lines, with heavy, high-speed
traffic, it is advisable to have the curves of large radius, so as to
avoid the necessity of reducing speed when passing round them.
Although a high-class fast train may be allowed to run round an 80
chain (5280 feet) curve at almost unrestricted speed, safety demands
that there should be a reduction of speed on curves of 40 or 30 chains
radius, and a very much greater reduction for curves of 20 chains
radius and under. A sharp curve will in some places form a greater
check to fast trains than a length of moderately steep gradient on a
straight line. In the former the trains running in either direction
must slow down for some distance before reaching the curve, round
which they should pass at greatly reduced speed, and then some
distance must be run before they can attain their full speed again. On
the other hand, with a rising gradient, on a fairly straight line, the
acquired momentum of the train will materially assist in ascending the
incline, and although the speed may be slackened as the train
advances, there may not be any very great diminution in the running
before the gradient is passed, and average level line reached again. A
reduced rate of running must be maintained round curves of small
radius, for, however substantial the works and permanent way, and
however well devised and constructed the rolling-stock, there is an
element of danger ever present when passing round sharp curves at
anything more than moderate speed. In the great rush for fast through
trains this point is very apt to be overlooked, and too little time
allowed for the running. Even with the fastest trains on any line
there are some portions of the route which must be traversed with
greater caution and less speed than others, either on account of sharp
curves or of gradients; and if those who are entrusted with the
preparations of the time tables do not possess the technical
information necessary to deal properly with the question of relative
speeds, there is the strong probability that the programme prepared
may be one both difficult and dangerous to fulfil. The spirit of
rivalry is a strong incentive to fast running, but prudence and common
sense should indicate that record speeds should only be attempted on       51
the straight or favourable portions of the line. There is,
unfortunately, the growing tendency to run faster and faster round the
curved portion of our lines, heedless of the close approach to the
limit of safety, and unless this excessive speed be controlled in
time, the result must be disaster on a very large scale.

A sharp curve leading into or out of a terminal station or main-line
stopping-station does not so much affect the train running as a sharp
curve at an intermediate point between stations where the train may be
expected to run at its maximum speed. Wherever it is possible it is
very desirable to avoid sharp curves on inclines, because there are
times when descending trains may acquire a considerable velocity, and
wheels tightly gripped by the brakes have not the same facility for
following the curves as when they are running free.

In rugged and mountainous districts sharp curves are almost
unavoidable, except by introducing a series of tunnels; but in these
districts both the gradients and curves are alike exceptional, the
speed is necessarily slow, and special precautions are taken for the
ascending and descending trains.

[Illustration: Fig. 30, 31, 32, 33, 34, 35, 36, 37, 38]

When setting out reverse curves on a main line a piece of straight
line should always be laid in between the termination of the one curve
and the beginning of the other, to allow of a proper adjustment of the
rails to suit the super-elevation adopted on each of the adjoining
curves. In station yards and sidings this is not so absolutely
necessary, the sorting of the carriages and waggons and the
marshalling of the trains being carried on at a low speed, which does
not necessitate any super-elevation of the rails on the curves. The
speed of the train regulates the amount of super-elevation to be given
on any particular curve, and to ensure smooth and safe running this
amount must be maintained uniform all round the curve. On curves of
small radius, guard, or check, rails are frequently placed alongside
the inner rail, as in Figs. 30 to 33, to check the tendency of the
engine to leave the rails and run in a straight line. For the
bull-head road a special chair is used, which holds both the
running-rail and the check-rail, as shown on the sketch, the rails
being kept the proper distance apart by the web portion in the centre,
which forms part of the casting. For the flange railroad, check-rails
are sometimes made of strong angle irons placed against the flange of
the running-rail, and bolted to the transverse sleepers. This method       53
is not nearly so strong or efficient as the arrangement shown on Fig.
33, with a cast-iron distance-block about six inches long, placed
between the running-rail and check-rail, and all tied together with a
strong through bolt. A bolt-hole is punched in the edge of the flange
of check-rail, and a crab bolt and clip holds the two rails on the
sleeper. The cast-iron distance-blocks are placed just outside the
sleeper, so as not to interfere with the holding-down bolt. Doubtless
these guard rails do good service, but if the leading wheels of the
engine have sharp or worn flanges there is the possibility that the
wheel, pressing against the high rail, may mount the rail, and throw
the train off the line. A more secure method is to place the guard
outside the high rail, as in Figs. 34 to 38. This can be done by securing
a strong continuous longitudinal timber to the cross-sleepers--or to
the cross-girders in the case of a girder bridge--with its outer or
striking edge protected with a fairly heavy angle iron. The top of
this outside guard above the rail level may be three inches or more,
according to the height of any hanging spring, or portion of brake
apparatus belonging to the rolling-stock. The distance between the
striking-face of the guard and the inside of head of rail should be
about 5 inches, or such width that before the flange of the wheel can
mount on the top of the rail, the face of the wheel-tyre will be
brought into contact with the striking-face of the outside guard, and
thus effectually prevent the wheel leaving the rail. The sketches show
some of the types applicable to the chair road, and to the flange
railroad. In Figs. 34, 35, and 37, the outside brackets are of heavy
angle iron cut off in lengths to correspond to the width of the
sleeper. In Fig. 36 the cast-iron chair is lengthened, and has an end
bracket to support the guard timber. In Fig. 37 a hard wood bolster is
fastened on the top of each sleeper, and on this is placed the
continuous guard timber. This method of increased security is
frequently adopted on girder bridges and long iron viaducts which are
on the straight, and in such cases it is usual to place the guards
outside each of the rails forming the track.

The introduction of bogie engines and bogie carriages has conduced
largely to the safe working of the train-service over the curved
portions of many of our home railways, as well as to the economy in
the wear and tear of permanent way and rolling-stock. The action of
long rigid wheel-base vehicles passing round sharp curves is               54
detrimental to all the parts brought into contact. Not only is there
the constant tendency to mount the rails, and spread the gauge, but
the tiny shreds of steel scattered all along close to the
rail--particles ground off the rails, or off the wheel-tyres, or
both--testify to useless wear, unnecessary friction, and great waste
of motive-power.

The gradual increase of accommodation and conveniences in the carriage
stock of European railways led to the gradual increase in the length
of the vehicles. The six-wheeled carriage superseded the four-wheeled
carriage, on account of its increased steadiness when running, but the
introduction of long sleeping-cars, dining-cars, and corridor cars
necessitated some better wheel arrangement than the ordinary six-wheel
type could supply. The six wheels had been spread as far apart as was
admissible for carrying weight and passing round curves, and something
had to be done to meet the demand for still longer carriages. Many of
the six-wheeled carriages at present running on our own home lines
have a fixed wheel-base as long as 22 feet, and with this length the
horn-plates must undergo a very considerable strain when adapting
themselves for the passage round curves of small radius. On a curve of
15 chains radius (990 feet) a chord of 22 feet will have a versed sine
or offset of 0·73 of an inch, and on a curve of 10 chains radius (660
feet) an offset of 1·10 of an inch. Fortunately, curves of the above
small radius are not very numerous on our main lines; but wherever
they do occur, the conflict between the long fixed wheel-base
rolling-stock and the permanent way must be very severe to both.
Several descriptions of eight-wheeled carriages have been tried on our
home lines; but the system which is now most in favour is the ordinary
bogie truck, which has been in use for so many years on all American
railways. A bogie truck is really a short carriage frame complete in
itself, with its wheels, springs, and brake appliances, and is
attached to the under side of the carriage body by a central pivot,
round which the truck can swivel or rotate sufficiently to adapt
itself to the curved portions of the line. With a bogie truck at each
end of a long carriage, the vehicle will pass as easily round curves
as on the straight line, side pressure, or grinding against the rails,
is obviated, and friction is reduced to a minimum. The bogie truck may
consist of four wheels or six wheels, according to the length and
weight of the carriage to be supported.

[Illustration: Fig. 39, 40, 41, 42]

Figs. 39, 40, and 41 show sketch elevation, plan, and transverse           56
section of one pattern of four-wheel bogie truck largely adopted in
American carriage stock, and although there are other types varying in
detail, the general principle remains the same in all. The diagram
sketch (Fig. 42) represents the two bogie trucks slightly swivelled to
adapt themselves to the curve round which the carriage is supposed to
be passing.

For carriage or waggon stock with an independent bogie truck at each
end, the central pivot and swivelling motion supply all the freedom
that is requisite; but for locomotives it is necessary to provide for
lateral as well as for swivelling movement. The driving and trailing
wheels--and sometimes one or two other pairs of wheels--work rigidly
in the frames, and as the normal position of the centre of the bogie
truck must be in the centre line of the engine for the straight line,
it is evident that some appliance must be introduced to allow the
truck to move laterally when the engine has to traverse the curves.

Figs. 43, 44, and 45 give sketch elevation, plan, and transverse
section of a swing-link bogie truck as applied to an ordinary American
locomotive. Its recommendations are its simplicity, its efficiency,
and its accessibility for inspection and lubrication. The swing-links,
which provide for the lateral movement, are direct acting, and do not
require any side springs of steel or indiarubber. All the principal
parts of the bogie are visible and not mysteriously cased in with
plate-iron boxwork.

In the sketches several minor details are purposely omitted and only
sufficient particulars shown to explain the method of working. The
under side of the upper centre plate which carries the cylinder
castings and smoke-box end of boiler is cup-shaped, and fits into an
annular groove or channel in the lower centre plate, which is
suspended from the framework of the truck by the four swinging links.
Practically the entire carrying and swivelling work of the bogie truck
is effected by the annular-groove casting moving round the cup-shaped
casting, and the centre pin is merely passed down through each to
guard against the risk of the one lifting out of the other from sudden
shock or derailment.

[Illustration: Fig. 43, 44, 45, 46]

The lateral movement of the truck is obtained by means of the four
swing-links. When the engine is on the straight road the centre line
of the bogie is on the centre line of the engine, and the links hang
in the positions shown on the sketch, inclined towards the centre; but     58
upon entering a curve they come into play, and allow the truck to move
out sideways to the right or left, according to the direction of the
curve, the one pair of links assuming a flatter angle, while the other
pair approach nearer to the vertical, the extent of side movement
depending on the amount of the curvature. When the engine enters the
straight line again, the bogie truck resumes its central position.

The Bissell truck consists of one pair of wheels connected to a
triangular framework, as shown in Fig. 46. The axle-boxes are attached
to the side of the triangle which lies parallel to the axle, the other
two sides terminate in a circular ring which works round a centre pin
fixed to the engine. These two sides are practically the radii of a
given circle, and permit a large amount of lateral movement, which can
be controlled by placing suitable stop-pieces to limit the side play
to the extent desired.

Radial axle-boxes have been tried on the engines of some railways. In
the best types the opposite boxes are braced together by a diaphragm,
or plate-iron framework, to ensure that both boxes work together. The
curved faces of the horn-blocks, in which the radial axle-boxes slide,
are struck from a centre taken at some point to the rear of the normal
centre line of the axle, and stops are placed at proper distances to
control the extent of lateral movement. Although the advocates of
radial axle-boxes may urge some points in their favour, there are few
engineers, if any, amongst those who have had practical experience of
both systems, who would for a moment claim for the radial axle-box
anything but a modicum of the many advantages obtained by the
four-wheeled bogie truck.

As one of the principal functions of a four-wheeled bogie truck for an
engine is to act as a path-finder, or guide, to the other wheels which
constitute the fixed or rigid wheel-base portion of the machine, it
follows, therefore, that the full benefit of the bogie truck can only
be obtained when it is placed at the leading, or front, end of the
engine. In this position the bogie, with its swivelling arrangement
and smaller weights, is the first to pass over the rails, and in doing
so shapes the course and prepares the way for the easy running of the
heavier wheel weights which have to follow. When the bogie truck is
placed at the rear end of the engine, its action is restricted to
affording lateral movement only, and the driving and coupled wheels
have to force or pound themselves round the curves in a jerky,
irregular manner, as compared to their smooth running when following       59
the leading or guiding influence of a bogie truck in front.

The wheel-base of a four-wheeled bogie truck for an engine should
always be greater than the gauge of the line over which the bogie has
to travel On the 4 feet 8½ inch gauge some of the best results have
been obtained with bogies having wheel-bases varying from 6 feet to 7
feet. Where the wheel-centres have been less than 6 feet, the running
has been found to be much less steady than with the wider spacing; and
where the wheel-base is not more than the gauge, there is a tendency
for the bogie to catch, or lock, when passing round sharp curves.




  CHAPTER II.                                                              60

  Works of construction: Earthworks, Culverts, Bridges, Foundations,
    Screw piles, Cylinders, Caissons, Retaining walls, and Tunnels.


Earthworks.--Under this heading may be classified cuttings and
embankments of earth, clay, gravel, and rock.

When setting out a line and adjusting the gradients, an endeavour is
usually made to so balance the earthworks that the amount obtained
from the cuttings may be sufficient to form the embankments. With
care, this may be effected to a considerable extent; but there will be
places where the material from cutting is unavoidably in excess, and
others where the cuttings are too small, or contain good rock, or
gravel, which can be more advantageously used for building and
ballasting purposes than for ordinary embankment filling. Or there may
be a large cutting which will provide enough material to form three or
four of the adjoining embankments; but the distance, or _lead_, as it
is termed, to the far embankment may be so long, and, perhaps, on a
rising gradient, that it would be cheaper to run the surplus cutting
to _spoil_, and _borrow_ other material for the far embankment from
side cutting or elsewhere. A long lead adds materially to the cost and
time of forming an embankment, as it not only necessitates a
considerable length of _service_, or temporary permanent way, but also
occupies much time in the haulage of the earth waggons. For distances
of half a mile and upwards, a small locomotive is more suitable than
horses for conveying the waggons.

To run to _spoil_ is the term applied to such of the material from a
cutting which, not being required or utilized in the formation of the
line embankments, is removed and tipped into mounds, or
_spoil-banks_, in some one or more convenient sites near the mouth of
the cutting. Sometimes the surplus material is disposed of by
increasing the width of the embankments. Material excavated in a           61
tunnel, and hoisted through the shafts to the upper surface, has to be
deposited in spoil-banks along the centre line of the tunnel.

To _borrow_ material to form an embankment is the term used when the
earthwork filling is not obtained from the cuttings
on the line. This borrowing is generally done by excavating
a trench on each side of the line, of such width and depth as
will supply sufficient material to form the embankment. Fig.
47 gives an example of an embankment thus made from side
cutting. In some cases a piece of high ground adjacent to the
embankment can be utilized for obtaining a portion, or even
the whole of the filling.

Increased material is sometimes obtained by widening the
cutting, or flattening the slopes, or both.

The degree of slope of a railway cutting must be regulated by the
nature of the material excavated. A slope of 1½ to 1, which gives for
every foot of vertical height a width of one foot 6 inches of
horizontal base, as in Fig. 48, is usually adopted for cuttings in
ordinary earth, good clay, sand, or gravel. There are some
descriptions of strong clay and marl which will stand at a steeper
slope, even at 1 to 1; but, on the other hand, there are some kinds of
clay which must ultimately be taken out to 2 to 1, and even 3 to 1.

It frequently occurs that the slopes of a clay cutting, taken out to
1½ to 1, appear to stand well for a time, but after exposure to the
frost and rain of one or two seasons, the material becomes loosened,
and forms into slipping masses, which slide down on to the line,
stopping all traffic, and have to be cleared away before train
operations can be resumed.

Cuttings through solid rock may be taken out to a slope of ¼ to 1, as
shown in Fig. 49, provided the material is compact, and there is not
too great a dip in the strata or rock-beds. Where the rock-beds lie at
a considerable angle, the slope on the high side will have to be made
flatter than the slope required on the low side, as shown in Fig. 50,
and great care must be taken to remove from the high side all loose or
disconnected pieces of rock which might come away and slide down on to
the line.

[Illustration: Fig. 47, 48, 49, 50, 51]

Strong dry chalk will generally stand at a slope of ⅓, or ½ to 1, but
when wet and mixed with flints it will be necessary to increase the
slope to not less than ¾ to 1. Where the rock is loose and
disintegrated, a slope of not less than ½ or ¾ to 1 will be required,      63
and at many points there will be detached threatening masses of rotten
rock which must be cleared away to a much flatter slope for safety. In
cuttings of this description it is frequently found necessary to clear
out a portion of the loose pieces of the lower cavities and build in
their place a facework of masonry to support the superincumbent rock.
Springs of water rising in the rock, or running over any part of the
rock slopes, must be properly provided for, and conducted to the
nearest channel. They should be carefully watched during the winter
season, when the frost, acting on the water penetrating the crevices,
splits and separates large pieces which were previously firm and
secure.

Instances will occur where a cutting has to be made through a thick
bed of rock and several feet of soft loose strata underneath. The
effect of forming a cutting through the soft strata is to induce the
heavy bed of rock above to squeeze or force out the softer material
below, and unless proper means were taken to avert such a disturbance,
the entire cutting would have to be excavated to a very flat slope.
The method adopted in such a case is to build strong face-walls of
masonry, brickwork, or concrete, underneath the rock, as shown in Fig.
51, with strong inverts placed at short distances. Suitable
arrangements must be made to take away the drainage water which will
collect at the back of the walls, and weeping-holes or outlets must be
left in the lower part of the walls to convey the water into the
water-tables on the line.

Where there is a depth of earth cutting on the top of the rock, the
earth should be cut away so as to leave a bench or space of 3 or 4
feet between the edge of the rock cutting and the foot of the earth
slopes, as shown on Fig. 52.

In cases of shelving rock, with earth or clay on the top, as shown in
Fig. 53, it is frequently found necessary to remove the whole of the
clay on the high side to prevent the possibility of its sliding off
the rock on to the line below.

[Illustration: Fig. 52, 53, 54, 55, 56]

In large cuttings it is usual to push forward a gullet of sufficient
width for one or two lines of waggons, as shown in Fig. 54. When this
has advanced some distance, strong planks or half balks of timber are
placed across the gullet, and the sides or wings of the cutting can be
excavated, the material wheeled to the gullet, and tipped from the
barrows into the waggons beneath. By this arrangement the work can be
carried on very expeditiously, as one set of men can be engaged            65
advancing the gullet and laying the track, while others are following
up and taking down the sides. A large number of waggons can thus be
filled in a day, and a small locomotive kept fully employed.

Occasions will arise where the material from a large cutting, situate
on a continuous gradient, as in Fig. 55, has to be carried in both
directions to embankment.

In wet weather, or if the cutting is at all wet, it would be almost,
if not quite, impossible to carry on the excavation at the upper end
to the proper formation level. The water would collect at the lower
level, and not having any means of escape, except by pumping, would
stop the work. In such a case the best way is to take out the cutting
at the upper end to a slight rising gradient, as shown in the sketch,
sufficient to carry away all water, and afterwards take out the lower
portion in the working from the other end of the cutting.

Cases will arise where it will be necessary to make a shallow cutting
through boggy peaty ground. If the boggy material be very soft, and
its thickness from the formation level to the solid ground below be
not great, it may be advisable to remove this extra thickness down to
the hard lower bed, and fill in up to formation level with strong
material. If, however, the bog or peat be too thick to justify its
entire removal, it should be excavated say down to two feet below
formation level, and a thick layer of branches of trees and strong
brushwood closely laid and packed the full width of the road-bed. On
this preparatory foundation must be placed good clean ballast to carry
the permanent way. Two or three extra sleepers should be allowed to
the rail length, and in some instances it will be necessary to
introduce two, or even four, rows of strong longitudinal timbers--half
balks--under the transverse sleepers. The object of all this extra
timber is to obtain a large increase of bearing area on the soft
yielding surface of the boggy material. Notwithstanding these special
precautions, the trackway will sink down a little during the passage
of an engine or train, but will generally return to its former level.
Good side drains or water-tables should be formed at each side of the
cutting to take away all rain and surface water.

In all cuttings it is desirable to have the line of formation on a
slight gradient, sufficient to carry away all rain water or spring
water which may be collected in the water-tables; but more                 66
particularly so is this necessary in a rock cutting, where the
material, being non-absorbent as compared with earth or gravel,
requires that all drainage must be carried away to the mouth of the
cutting.

In carrying out railway embankments and road approaches, it is usual
to form the sides to a slope of 1½ to 1, as shown on Fig. 56.
Occasionally the cuttings produce material which might stand at a
rather steeper slope, but considering the effects which might
afterwards be produced by heavy rains falling on the sides, it is more
prudent to adopt the flatter slope of 1½ to 1. Some descriptions of
clay will not stand at the above slope, but require a slope of 2 to 1,
or even 3 to 1.

When proceeding with the earthworks, it is customary to first remove
and lay aside a layer, say 9 inches in depth, of soil and earth from
the seat of the embankments and top widths of the cuttings, to be used
afterwards in soiling the trimmed and finished slopes of the cuttings
and embankments. This soil being removed, the actual work of the
excavation can be commenced. The working longitudinal section will
give all the necessary particulars as to position of the mouths of the
cuttings and the depths at the various chain-pegs, and the top widths
of the cuttings can be ascertained by calculation, if on even ground,
or from the cross-sections if on side-lying ground, according as the
material may be earth, clay, or rock.

For facility of carrying on the works, reliable bench marks, or
reduced level stations, must be established at convenient distances
along the route of the line, and from these and the fixed chain-pegs
the correct line of formation level can be checked from time to time
as the work proceeds.

For ordinary earth or clay cuttings, the usual tools are picks and
iron crow-bars for loosening, or _getting_ the material, and
shovels for filling into barrows, carts, or waggons. For heavy
earthworks, steam excavators are now largely employed. Great
improvements have been made in this class of machinery, in the way of
perfecting the method of excavating lifting, and filling the material
into the earth-waggons.

In nearly all rock cuttings the greater portion of the material has to
be taken out, or loosened, by blasting with gunpowder, dynamite, or
other explosive. The number and extent of the charges will depend upon
the nature of the rock and its stratification, and also on its position    67
as regards proximity to buildings or residential property.

Where the rock is loose, or disintegrated, the pieces can generally be
readily separated by picks and bars without having to resort to any
great extent of blasting.

[Illustration: Fig. 57, 58, 59, 60, 61, 62, 63, 64, 65, 66]

The first of the material excavated in the cuttings is generally
conveyed in wheelbarrows to form the commencement of the adjoining
embankments. When the wheeling distance becomes too far for economical
barrow work, ordinary carts or three-wheeled carts, sometimes termed
_dobbin carts_, are brought into operation where the cuttings and
embankments are light; but where the earthwork is heavy, both in
excavation and filling, a service or temporary road of light rails and
sleepers is usually laid down to carry strong _tip_ earth-waggons. For
moderate distances these waggons are hauled by horses, but for
distances over three-eighths of a mile a small locomotive is more
speedy and economical. Fig. 57 shows one form of dobbin cart; the
wheels are made with good broad tyres, so as not to sink too deep into
the soft ground, and the body being attached to the framework by a
pivot or trunnion on each side, can be readily tilted over, and the
earth tipped out, by releasing the holding-down catch. Where the
ground is soft and wet, or of a very loose sandy nature, the work of
hauling these dobbin carts is very heavy on the horses, and in such
cases it soon becomes an advantage to lay down a service road of rails
and sleepers. This service road is formed of light rails manufactured
for the purpose, or old, worn rails no longer fit for main-line work,
spiked down on to rough transverse wooden sleepers. The end of the
embankment in course of formation, and where the earth is being
tipped, is termed the _tip head_. Two or more roads are required at
the tip head to form the embankment to its full width. Fig. 58 gives a
sketch plan of a service road near the tip head. The width is shown as
for a double line. The earth-waggons are hauled along the line from
the excavation, and brought to a stand at the point A. If a
locomotive has drawn the waggons, it is then detached, moved forward,
and shunted back into the siding BC. A horse accustomed to tipping
then takes one full waggon at a time over one or other of the two
turn-outs, DEF or DGH, to the tip head, sufficient impetus being
given to the waggon to run the front wheels off the ends of rails on
to cross-sleepers laid close, with a steep rise, and backed up with        69
earth. This suddenly checks the frame of the waggon, and the body
containing the excavated material revolves on its trunnion, tilts up,
and shoots out the material well forward, so that the man in charge of
the tip head, who also knocks up the “tail-board catch,” is able to
level off the filling without assistance. The empty waggon is then
hauled back, and turned into the siding BC, and another full waggon
taken forward and tipped, until all the waggons of the rake are
emptied. Ten waggons generally form a rake when the work is pushed
forward vigorously, each waggon holding about three tons. The tip head
horse pulls the waggon by a trace-chain having a spring catch at the
end, by which the driver releases the horse at the right moment. It is
very important that this spring catch should be kept in good order,
because occasionally too much impetus is given to a waggon, which,
running over the tip head down the slope, would drag the horse with it
if the spring catch did not act properly. Good firm foothold must be
provided for the tipping horse.

The tip head should never be carried across culverts or bridges until
they have been well backed up, and protected by a thick covering of
earth or clay, wheeled in with barrows to an equal height on each side
of the masonry, so as to prevent undue side pressure.

Fig. 59 gives a sketch of one form of end-tipping waggon. In some
cases the wheels are made of cast-iron, but as these are readily
broken during the rough handling to which earth waggons are exposed,
it is questionable whether the light wrought-iron wheels, with light
steel tyres, used on some works, are not more economical in the long
run. The framework and body are made of strong undressed timber, well
bound and bolted together. The tail-board catch keeps the body of the
waggon in its proper horizontal position while loading or running, but
when released leaves the body free to tilt up, and to revolve on the
front trunnion by means of the circular clip A. The same principle
is also applied to side-tipping waggons which are used for the
widening of embankments, or formation of platforms and loading-banks.

The permanent way of these service roads is generally made as simple
as possible. A pair of movable rails are used instead of switches, as
shown in Fig. 60. These rails are linked together by iron tie-rods,
and pulled or pushed over into position for one or other of the roads      70
by means of the handle at A. A stout iron pin, or iron
clamping-plate, serves to retain the rails in position during the
passing of the waggons. In a similar manner, a short rail working on a
pin, or pivot, is made to answer the purpose of an ordinary crossing.
The rails are laid complete and continuous for the one road, and for
the second road the outer rail is laid sufficiently high to cross over
the rail of the first road. A piece of rail is then secured by a
centre pin, or pivot, to the cross-sleeper, as shown on Fig. 61. This
pivoted rail is pulled over into the position shown by the dotted
lines, to allow the passage of waggons on the one road, or pulled
across to the end of rail at B, for waggons to pass on or off the
other road. In the latter case an iron pin or clamp serves to keep the
pivoted rail in position. As these service roads are merely laid down
on the soft loose material brought forward for filling, they require
constant packing and lifting to prevent them working into depressions,
which might cause the waggons to leave the rails.

To indicate the height of the embankment filling, strong stakes or
poles must be firmly set in the ground at each chain-peg. On each of
these poles two cross-bars must be fixed, the lower one placed to the
correct height of the embankment, and the upper one to show the amount
allowed for subsidence. The excavated material, as brought from the
cuttings, is in a soft, loose condition, and an allowance must be made
for its settlement, or subsidence, as the embankment becomes
consolidated. This allowance will, of course, depend on the height of
the embankment and the quality of the material, but for ordinary earth
and clay it is customary to allow about one inch to the foot of
height, which is equal to about 8 per cent.

When forming embankments over very side-lying ground, it is necessary
to cut steps in the sloping surface on which the filling material has
to be placed, as shown in Fig. 62. These steps give a hold to the new
earthwork, and check the tendency to slide down the hillside.

Embankments have frequently to be carried over ground which is low,
soft, and wet, but not boggy. If the culverts and drains are
sufficiently large, and properly arranged, these places are not likely
to cause much future trouble.

For a thoroughly soft deep bog, however, it is most difficult to make
any accurate calculation as to the amount of embankment filling which      71
will be necessary to form a permanent foundation for the line; and the
construction of a high heavy embankment across such a place is one of
those undertakings which every engineer is most anxious to avoid. A
large quantity of material may be tipped into the bog, and seem to
stand fairly well for a time, and then suddenly disappear altogether.
More material has to be brought forward, and will most likely
disappear in a similar manner. The filling material being heavier than
the bog on to which it is thrown, falls through, and displacing the
soft semi-liquid matter, continues to sink down lower and lower until
it is stopped by a harder stratum underneath. In a measure the
operation somewhat resembles the tipping of earth into a lake; the
material will go down until it meets with a solid bottom, and in going
down it assumes its own natural slope, and forms for itself a width of
base corresponding to its height. It will be readily understood what
an enormous amount of filling material will be swallowed up in
following out such a process. On a very soft bog, say 20 feet in
depth, over which an embankment 20 feet high has to be formed, the
extent of the actual earthwork filling will very probably closely
approach the outline shown in Fig. 63. The upper portion, ABCD,
representing the embankment proper, will contain about 133 cube yards
to the yard forward, whereas the lower portion, CDEF, which has
displaced the soft boggy matter, will contain about 266 cube yards to
the yard forward, or, in other words, the filling which is out of
sight will be double the filling which is in view above the section
ground line.

Apart from the large amount of filling consumed in forming this
semi-artificial island, the progress of the work itself is very
perplexing. A long length of the bank may have been raised again, once
or twice, to the proper height, and may have carried rails and
earth-waggons for some weeks, and then sink all at once several feet.
The sinking, too, may not be uniform, but may produce fissures,
depressions, and separation of the earthwork which will necessitate
much care when bringing forward fresh filling material. The bog may
not be of the same consistency throughout, there may be some layers of
harder material, such as imbedded trunks of trees, and these may
sustain the filling for a time, and then yield under the increasing
weight of the superincumbent mass. Even when the embankment is
finished throughout, and shows no sign of sinking, it should be very
carefully watched for a long time for any indication of further            72
movement.

When the bulk of the material has been taken out of an earth or clay
cutting, the work of trimming the slopes should be put in hand, so
that any surplus left on the wings, or sides, may be removed, and
carried away before stopping the earth-waggons. The angle of slope
having been decided, a battering rule of light wooden boards is made
to correspond to the slope, and in form similar to that shown in Fig.
64. A plumb-bob is suspended from a fixed point, A; the lower end,
B, is then held against a peg or mark which indicates the correct
level and width of the cutting at the place, and the upper end, C,
is raised or lowered until the plumb-bob string coincides with the
vertical line marked on the rule from A to D, and the plumb-bob
rests steadily in the space cut for it at D. With this battering
rule a length of seven or eight feet, according to the size of the
rule, is first trimmed to the correct slope, and by continuing the
application of the rule up the side, a correct slope line is obtained
from bottom to top of slope at that place. By repeating the process at
convenient distances along the cutting, a series of correct slope
lines are obtained, and the intermediate space can readily be trimmed
to correspond.

The same form of battering rule and method of working is applicable
for trimming the slopes of the embankments.

When the slopes of the cuttings and embankments have been trimmed,
vegetable soil, which has been laid aside, or reserved as previously
described, should then be spread evenly over the slopes to the uniform
thickness of not less than four inches, and the whole sown with good
grass seeds to form a strong sward.

The trimming, soiling, and sowing of the slopes not only gives a more
finished appearance to the earthworks, but the strong grass, when once
well grown, binds the surface together, and helps to resist the
injurious effects of heavy rains and melting snow.

There are many places abroad where a neat finish to the earthworks is
considered quite a secondary matter, or where it would be difficult to
obtain suitable soil to spread on the slopes. The earthworks are
hurried forward to allow the iron highway to be laid down as quickly
as possible, the slopes of the cuttings and embankments are only
roughly trimmed, and nature is left to supply such grass or vegetation     73
as may spring up, or be self-sown.

The fencing in of a line of railway serves the double purpose of
defining the boundary of the company’s property, and of forming a
barrier for the prevention of trespass of persons and animals on to
the line. For our home lines, fencing is compulsory, and the same
obligation exists on many foreign railways. In our colonies, and out
in the far West of the United States, and in newly opened out
countries, fencing, except near towns and villages, is rather the
exception than the rule; people and animals roam at will from one side
of the railway to the other wherever they find a convenient crossing
place, and the cowcatcher of the engine has to be depended upon for
throwing aside any animal which may be standing, or resting, on the
line of rails at the passing of a train.

The description of fence will be influenced by the locality, and the
materials conveniently obtainable. Where stone is plentiful, perhaps
brought forward out of the cuttings, and labour cheap, a masonry wall
will be found a most suitable permanent fence. Any fence to be of
service should not be less than four feet high. A wooden post and rail
fence is much in favour in some districts, the posts being firmly set
or driven into the ground, and four or five stout bars nailed on to,
or set into, the upright posts. This fencing does not last very long,
the pieces are small in size, and soon fail from decay. Quick or
hawthorn hedges, when fully grown, make a good fence, but require
careful attention to prevent gaps being made by roving cattle. They
also require constant trimming and cutting. The quicks are generally
planted in a mound formed by cutting a continuous ditch, or gripe, as
shown in Fig. 65. The ditch serves as a drain to take away water
running down the slopes of the embankments, small openings in the
mounds, or drain pipes through them, forming leaders to conduct the
water to the ditch or gripe. The outer edge of the ditch represents
the boundary of the railway property, unless specially arranged
otherwise.

Galvanized iron-steel wire fencing, if not made too light, is strong
and durable, and very easily kept in order.

The wires may be secured to strong wooden posts, which should be
creosoted, and not placed too far apart, or to iron posts or standards
of angle iron or tee-iron section. The straining-posts, whether of iron    74
or timber, must be stronger than the intermediate posts, firmly fixed
into the ground, and well stayed, to withstand the pulling and
tightening of the wires. There are many places where a quick fence
would not grow, and where the ground is too soft to carry a wall. In
such cases a good galvanized-wire fencing will fulfil all
requirements. The strand wire is better than the plain wire, as its
method of manufacture necessitates the use of a superior material, and
it is easier to straighten and keep in good order. An extra strong
fence is often made of six, eight, or more rows of round rod-iron
secured to wrought-iron uprights of bar-iron or tee-iron.

In hot countries abroad an excellent fence is obtained by planting a
species of cactus or aloe in a similar manner to the quick fences at
home, and as shown in Fig. 66. These cactus plants are readily
obtained, are very hardy and quick in growth, and with their large
spike-shaped leaves form such an almost impenetrable barrier that few
animals will attempt to pass.

Road approaches to bridges over or under the line, or to public road
level crossings, may be fenced in the same manner as the line proper.
If quicks are adopted, it will be necessary to put up a light wooden
fence also to protect the young plants until they are well grown. Near
towns and villages it is frequently found advisable to adopt a
specially strong wooden fence, or close-boarded fence, where the
approach is an embankment, and too newly made to carry a wall.

Gates for farm or occupation level crossings may be made of wood or
iron. As a rule, iron gates are preferred, as they can be supplied at
the same cost as wood, and are very much more durable. Gates for
public road level crossings have to be so placed that they will either
close across the railway or across the road; their length will
therefore depend upon the width and angle of the road crossing. It is
better to make these gates of wood, so that, in the event of a train
running through them, there may be less risk of injury to life and
rolling-stock than if they were made of iron. For footpath crossings,
small gates, wickets, or stiles may be adopted of such form as may be
found most suitable for the requirements.


Culverts and Drains.--Before proceeding with the formation of the
embankments, it is necessary to construct the culverts and drains
which will be covered over by the earthworks. Any existing drains
which may be of too light a description must be reconstructed in a         75
more substantial manner. It is a simple and comparatively inexpensive
matter to rebuild a drain before the earth filling is brought forward,
but it is a costly work to open out an embankment, and rebuild a
culvert afterwards. Unless the seat of an embankment is well drained
and kept free from the accumulation of running water, the earthwork
will be exposed to washing away of the lower layers, and consequent
subsidence. Each watercourse or open drain must be provided for either
by a separate culvert of suitable size or, as may be done in some
cases, by leading two or more watercourses into one, and thus passing
all through one culvert of ample capacity. When fixing the sizes of
the culverts they must not be limited to the normal flow of water, but
a large margin must be allowed sufficient to meet extraordinary
floods. The depth of the bed or invert of a culvert is a very
important point. If laid too high, and the stream above should at any
time deepen, the high invert would check the flow of the water, and
would also incur the risk of being undermined and gradually carried
away. If, on the other hand, the invert be laid too low, it will
gradually silt up to the level of the stream-bed alongside, and there
will be so much of the culvert space lost for all practical purposes.
In cases when the invert of a culvert has to be laid at a special low
depth to allow for future improvements in drainage, it is advisable to
give extra height from the invert to the crown, or top, so as to
provide ample waterway in the event of any silting up in the mean
time. Particular care should be taken when building the foundation of
a culvert. It has to be laid on the site of the watercourse, or on a
new channel which will ultimately form the watercourse, and it should
be built sufficiently deep into the ground to avert as far as possible
the chance of water finding a course through below the foundation.

The invert may be of stone pitching or brick if the current is not
rapid, or liable to bring down stone boulders from its gravelly bed.

With a stream-course having considerable fall, and which carries with
it large stones, roots of trees, and other _débris_, the invert should
consist of strong pitching, composed of large-sized, rough-dressed
stones of hard, durable quality, capable of withstanding the pounding
of the boulders brought down during floods. A soft description of
stone would be quite unsuitable for the invert of such a stream; the
pitching would wear away quickly, break, and become detached, leaving      76
the foundation and side walls exposed to the cutting inroads of the
water.

Where large flat bedded stones or flags of tough quality can be
obtained, they form good covers, or tops, for culverts up to two feet
in width. They should have not less than nine inches bearing on the
side walls, and their contact edges should be fairly dressed, so as to
fit sufficiently close to prevent the embankment filling from falling
through.

Where the stream, or run of water, is very small, strong earthenware
pipes, 9 inches or 12 inches in diameter, well bedded, may be
sufficient to carry away all the water likely to arise. For small
springs in low swampy ground, dry stone drains may in many cases be
used with advantage. These are made by cutting a trench, say two feet
deep by twelve or eighteen inches wide, in the seat of the embankment
from side to side, and filling it up with dry rubble stones, not
boulders, hand-laid, the upper layer placed on the flat to keep the
earthwork as much as possible from filling in between the stones.

In soft boggy ground, where the depth to a hard bottom is very
considerable, wooden culverts are frequently adopted. Although these
cannot be classed as permanent structures, still, when they are made
of sound well-creosoted timber, and substantially put together, they
last for a number of years. Sometimes they are made cylindrical in
section--a species of elongated cask with strong iron hoops every few
feet. Others are rectangular in section, made with two strongly
trussed side frames connected and covered with cross-planking and
longitudinal tie-planking on the top and bottom.

Wooden culverts are seldom made of very large size, rarely exceeding
an opening of 3 feet, and it is considered preferable to use two of
these culverts of moderate dimensions than one of large size. Figs. 67
and 68 give sketches of wooden culverts of cylindrical and rectangular
section, and Fig. 69 of flag top culverts of 12-inch, 18-inch, and
2-foot openings. In masonry culverts the side walls are shown to be of
rubble stonework, but brickwork can be used instead, provided the
bricks are well burnt, hard, and capable of withstanding the action of
the water.

[Illustration: Fig. 67, 68, 69, 70, 71]

In Figs. 70 and 71 are shown types of arch-top culverts of 4 feet and
6 feet span respectively. The arch portion is shown to be of brick,
which, as a rule, is cheaper than stone rings, which must be cut and       78
dressed to suit the small radius of the arch. The side walls may be of
brick of good quality. Occasionally they are built of concrete. The
wing walls may either be carried out in the direction of the stream,
as in the sketch of the 6-foot culvert, or they may be built
transverse, as shown on the 4-foot culvert, whichever arrangement is
found to work in the best for the case in question.

For arch culverts on very steep side-lying ground it is better to
build the arch-top in steps, as shown in Fig. 72, instead of forming
it parallel to the invert, or slope, of the stream-course. The level
portions of the arching give a better hold for the embankment than
could be obtained on a long inclined surface of brickwork or masonry.

The writer has built a large number of culverts of this type for
mountain streams on steep hillsides, and has found them to prove
satisfactory in every way.

In embankments alongside tidal rivers, or across the corners of
estuaries of the sea, culverts have frequently to be so constructed
that they will permit the passage of the drainage water from the land,
or high side, without admitting the tidal water. This can be arranged
by placing at the lower end of the culvert close-fitting hinged-flap
valves opening outwards. When the tide has gone down the weight of the
fresh, or land, water swings the flap-valve sufficiently open to allow
of a free passage; and, on the other hand, when the tide rises, the
pressure of the water against the face of the flap-valve keeps it
tightly closed, and prevents ingress of the salt water.

Culverts are sometimes fitted with lifting-valves or doors, which can
be raised or lowered to serve irrigation purposes. The door, which
works in guides, is made sufficiently heavy to fall with its own
weight, and the raising is effected by means of a screwed
suspension-rod working in a well-secured fixed nut.

In cases of soft or treacherous ground, timber-piling or wide
bed-courses of cement concrete are necessary to form firm foundations
for culverts. Drains and streams which are intersected by a railway
cutting have to be dealt with according to their size and their height
above the finished rail level. The water from a small drain or field
spring may be conducted in pipes down the slope of the cutting into
the water-table, or side drain, at formation level, and will be thus
carried away to the lower level at the entrance of the cutting. In
many cases streams can be diverted, and the water led away to some         79
lower point without the necessity of actually crossing the railway.
With a large stream, where it is essential that the water should be
conveyed across the line and continue on its ordinary course, it may
be carried over in iron pipes or iron trough if there is ample
headway, or in iron syphon pipes where the height is not sufficient.
The iron pipes or trough can be supported on masonry or brick piers,
or cast-iron columns, the height from the rails to the underside of
the conduit being not less than that adopted for the over-line
bridges.

Occasionally the pipes can be carried across on an over-line bridge,
either by placing them under the roadway or on small brackets outside
the parapet.

With the syphon arrangement the iron pipes must be laid down the
slopes of the cutting and under the road-bed of the permanent way. The
pipes must be continuous, strong, and firmly connected at the joints
to prevent leakage. The inlet and outlet ends of the pipes should be
securely built into receiving-tanks of masonry, brickwork, or
concrete, to ensure an uninterrupted flow of the stream, and also to
prevent any of the water from percolating through under the pipes and
on to the railway. As a precautionary measure, it is well to place
iron gratings some little distance in advance of the syphon pipes to
intercept and collect any brushwood, straw, or other things which
might be brought down with the stream.

Fig. 73 gives an example of the syphon arrangement as constructed with
two cast-iron pipes placed side by side.

Railway works carried out in cities and large towns, whether they take
the form of cuttings, embankments, arching, or tunnels, are certain to
cause a very considerable disturbance of existing drains, corporation
sewers, gas-pipes, water-mains and underground telegraph wires. Some
of these underground works may be so peculiar and complicated as to
necessitate a slight deviation from the course originally intended for
the line. Suitable provision will have to be made for each of the
items interfered with by the railway, and the substituted work must be
carried out to the satisfaction of the constituted authorities within
the municipal boundaries.

[Illustration: Fig. 72, 73]


Bridges.--Amongst the many bridges and viaducts which have to be
built during the making of a railway those constructed over rivers and
waterways are generally the most important The bridging across any         81
navigable river or tidal water can only be effected in compliance with
conditions imposed by the authorities controlling the navigation
rights. These conditions will place restrictions as to the number and
distance apart of the piers, as well as the height from high water
level to the under side of the arches or girders. For rivers having a
constant traffic of sea-going vessels of large tonnage and lofty masts
the authorities will demand great height or headway as well as large
spans; and if to this be added a deep water-way and bad foundations,
the work to be constructed becomes one of considerable magnitude. The
banks of the river must be carefully studied to find the most
favourable point for crossing, and in some cases it may be prudent to
make a detour of two or three miles. The crossing at a great height
involves the construction of the approach lines at a great height
also. If the river is in a deep valley with high sloping sides the
natural contour of the ground facilitates the formation of the
approach lines; but with a river on a low, wide, open plain, inclined
approach lines add enormously to the cost of construction, as well as
to the cost of permanent working.

If the number of sailing craft passing up and down the river be
moderate, and, perhaps, only passing at high water, the authorities
may permit a low-level viaduct with an opening bridge.

There are thus the two systems: the high-level viaduct, which allows
trains to pass over and vessels to pass under at any and all times,
and the low-level viaduct with opening bridge, which, if open for
vessels, is closed for trains, or _vice versâ_.

Every crossing of a navigable river will have to be considered and
dealt with according to its own individual requirements. An
arrangement suitable for the one may not be admissible or prudent for
the other. A frequent and important train service might be much
interfered with by an opening bridge, and, in a similar manner, an
opening bridge might cause much interruption and detention to the
navigation of the vessels on the river.

[Illustration: Fig. 74, 75, 76, 77]

Where a low-level viaduct with opening bridge can be adopted, there
will be a very great saving of expenditure; and there are numbers of
such viaducts in existence, accommodating a large railway and river
traffic without inconvenience. Even with a low-level viaduct the
height from water-level to the under side of the girders of the various    83
fixed-spans will generally be sufficient for the passage of barges and
small craft, leaving the opening portion to be used by the larger
vessels.

The principal openings for these large river viaducts are generally
constructed for girders, partly on account of the greater facility of
girder work for large spans, and also for the advantage of having one
uniform height, or headway, from pier to pier.

For a high-level viaduct across a deep-water river, the cost of the
lofty piers forms a very important part of the undertaking. Each pier
will require its own cofferdam, caisson, or other appliance for
obtaining a suitable foundation. The deeper the water, the more costly
the arrangement for foundation; and the higher the pier to rail-level,
the greater the amount of material in the construction of the pier.
The consideration of these two points will at once show that it is
very desirable not to have more of these costly piers than is actually
necessary, and in studying out the design it will be a question for
calculation how far the spans may be increased so as to dispense with
one or more piers.

In every work of this description there is a relative proportion
between span and height, which will give the most economical result
from a cost point of view; the proportion varying according to the
depth of the water and description of ground for foundations. An
increase in the span will naturally necessitate an increase in the
thickness of the pier; but where a cofferdam, or arrangement for
putting in the foundations, must in any case be made, a small addition
to its width may not necessarily form a large increase to its cost.

Figs. 74, 75, 76, and 77 are sketches of high-level railway viaducts
which have been constructed with great height, or headway, to allow
large vessels to pass under at all times without interruption. This
description of work is very costly, not only in the deep-water
foundations, but also in the heavy scaffolding and appliances
requisite for building piers and girders at such an elevation above
the ground-level. The hoisting of the material alone forms an
important item where such vast number of pieces have to be lifted to a
height of 80, 90, or 100 feet.

[Illustration: Fig. 78, 79]

Figs. 78 and 79 are sketches of low-level viaducts constructed with
one large opening span, or swing-bridge, for the passage of vessels.
The girders and roadway of such opening span are usually constructed       85
as a compact framework, which revolves on a centre placed in the
middle of a circular roller path or species of turn-table. The
portions of the rotating opening bridge, although not always the same
length on each side of the centre-pin, are generally very carefully
balanced, to preserve the equilibrium of the entire mass when swinging
round for the passage of vessels. To ensure stability in working, and
steadiness during heavy gales, a liberal diameter should be given to
the roller path of all swing-bridges having large span and great
weight.

Lattice, or truss, girders are preferable to plate girders for
swing-bridges of considerable opening, as they present less surface
area to the action of the wind.

The opening and closing of these bridges is effected by wheel-gearing
actuated by hydraulic, manual, or other motive-power. The revolving
machinery should be set solid and true, well protected from the
weather, and, at the same time, readily accessible for constant
inspection, lubrication, or repair.

Figs. 80 to 85 are sketches of various types of railway bridges
constructed for smaller openings across narrower rivers, water-ways,
or canals. Fig. 80 is an example of what is known as a _bascule_
bridge. This particular bridge is made in two halves, meeting in the
centre of the span, the tail end of each half being provided with
heavy counterweights to assist in opening or tilting up the bridge for
the passage of vessels, or lowering it down for railway traffic. Each
half of the bridge swings on horizontal axles, and the raising or
lowering is effected by means of hand winches or other motive-power,
actuating wheel-gearing working into toothed vertical segments
attached to the tail end of each half. The same principle has also
been applied to bridges having only one leaf to tilt up to clear the
passage way.

Railway bridges of this pattern are now very rarely adopted. They have
the great drawback that when raised to the vertical position, a very
large area is presented to the action of the wind, and this defect
might lead to very serious consequences in the case of a bridge
situated in an exposed locality. An open-work floor diminishes the
wind area, but a very large surface must necessarily remain.

[Illustration: Fig. 80, 81, 82, 83, 84, 85]

Fig. 81 illustrates what is known as a _traversing bridge_. In this
case the width of the opening passage-way and the adjoining span are       87
made the same, and the girders for the two spans are constructed in
one continuous length. By means of gearing attached to the fixed
portion of the work, the continuous length of girder, with its
roadway, is first slightly raised or lowered, and then drawn back on
rollers sufficiently far to leave the opening span quite clear for the
passage of vessels. A reverse movement of the gearing causes the
movable girders and roadway to travel back and return to their
original position ready for the train traffic.

Opening bridges are sometimes constructed on this system in cases
where the level of the rails is only a few feet above the level of the
water, and where there is only one water opening, and that not more
than 20 to 30 feet wide. In such bridges the movable portion is rolled
back along iron rails, or plates secured to masonry walls, or strong
pile-work. This class of bridge is cumbersome, slow to move, and is
now but very rarely adopted.

Fig. 82 shows a type of simple _lift_ bridge, of which there are but
few examples remaining. In this particular bridge the girders and
roadway form a solid framework, which rests on the abutments during
the passage of the trains. Strong chains, secured to the corners of
the framework, pass over large sheaves on the top of the iron
standards, and then round drums placed below the level of the rails,
and terminate by attachment to heavy counter-weights suspended in iron
cylinders. The counter-weights are adjusted to approximately balance
the bridge, so that a moderate power applied to the wheel-gearing on
the drums is sufficient to raise the roadway to the required height.
This class of opening bridge is only suitable for the passage of
barges and small craft without masts; and it requires the
re-adjustment of the counter-weights when the roadway varies in
weight, in consequence of rain or repairs.

Figs. 83, 84, and 85 are sketches of small _swing_-bridges constructed
for narrow waterways. Although differing in appearance, they are all
practically on the same principle, with centre pin and roller path,
and are similar in general arrangement to the large-size-opening
swing-bridges shown in Figs. 78 and 79.

[Illustration: Fig. 86, 87, 88]

The _swing_-bridge arrangement is so simple in construction,
convenient for inspection, and easy to maintain, that where possible
it is now generally adopted in preference to any other system. The         89
weights on centre pin and roller path may be distributed as considered
most expedient, and by means of suitable appliances the weight may be
altogether taken off the centre and rollers when the bridge is closed
for the passage of trains.

There are many wide rivers which, although not navigable in the
ordinary acceptance of the term, nevertheless require bridges of large
spans to provide free waterway for the floating down of rafts of
timber. Away in the high ground, in the timber-growing districts,
trees are felled, sawn or cut into long poles, logs, or scantlings,
and hauled to the banks of the river. The timbers are then formed into
large rafts of the most convenient form for floating down to the place
of distribution or port for shipment. Even with old experienced
floaters, using their long sweeps in the most skilful manner, it is
difficult to take anything but a very irregular course down the
stream. Under the most favourable circumstances one of these large
rafts is an unwieldy, awkward craft to manage; but in a river full of
twists and turns, with reaches varying from comparative smooth water
to miniature rapids, the current carries the huge mass surging along,
and only a clear, unobstructed channel will enable its navigation to
be carried out with safety. The presence of a pier in the main
waterway might cause destruction to the rafts and loss of life to the
men. The vested interests in floating rights are tenaciously guarded,
and no new bridge would be sanctioned which would in any way interfere
with the waterway or endanger the passage of rafts down the river.
Bridges of this description are much less costly than those over deep
water--navigable rivers. Excepting the large spans, the rest of the
work is comparatively simple. The water is generally shallow, and much
reduced in quantity during the summer months. Good foundations can
generally be obtained without going to any great depth. The headway
may be kept low, or of such height as may best suit the purposes of
the railway, and be sufficiently well up out of the way of the floods
which may take place from time to time on the river.

[Illustration: Fig. 89, 90]

Fig. 86 is a sketch of a bridge constructed over a river much used for
rafting purposes. The large span is over the main channel, and the
small spans are over a wide gravelly foreshore, which is only covered
with water during exceptionally high floods in the autumn or winter.       91
No rafting can be carried on when the river is in flood; the current
would be too strong to permit of the raft being kept under control.

Fig. 87 is a sketch of a similar bridge where the river is confined to
a regular channel between two sloping banks of strong clay.

Fig. 88 shows a bridge erected over a narrow rocky pass in the river.
The channel is hemmed in by the almost perpendicular sides of mountain
granite, there are no banks to overflow, the flood waters cannot
spread laterally, however much they may increase in depth, and with
building-stone at hand in abundance, and foundations formed in the
solid rock, the situation is one of the most favourable for a strong
permanent bridge. The cast-iron arch of 150-feet span has a graceful
appearance, and harmonizes well with the surrounding scenery. A small
masonry arch at each end of the bridge provides for communication
along the banks of the river.

With rivers which are neither under the control of navigation
authorities nor used for rafts of timber, there is much greater
freedom for the designing and carrying out of bridges or viaducts
suitable for the actual physical conditions of the locality. The
headway will be guided only by the height of the railway to be carried
across, and by any flood-water levels which may affect the work. The
size of the spans will be regulated by the width of the river, the
depth of the water, and the nature of the ground into which the piers
have to be built. For broad, shallow rivers with good firm river-beds,
piers may be built at moderate cost, and comparatively small spans
adopted; on the other hand, with a broad deep river it will be better,
as previously explained, to reduce the number of piers and increase
the span. In the one case, for example, a river 150 feet wide may be
crossed with three spans and two piers in the shallow water, as in
Fig. 89; in the other it may be more prudent and economical to cross
in one span, without any intermediate pier, as shown in Fig. 90.

[Illustration: Fig. 91]

Next in importance to the large bridges and viaducts over rivers are
the viaducts which have to be constructed for the crossing of deep
inland valleys. The occurrence of one of these deep valleys between
long lengths of average table-land renders necessary either a series
of cuttings and falling gradients to get down to a low level, or the
erection of high-level works to continue onward the rail-level at the      93
height already attained. A decision to adopt the latter course brings
forward the consideration as to the method of carrying out the work.
To form a high embankment across such a valley would entail an
enormous expenditure for earthwork, and several openings, or bridges,
would have to be made in the embankment for streams, rivers, and
roadways. Instead, therefore, of making this part of the line entirely
of embankment, it is usual to carry the earthwork forward until the
height is about 25 or 30 feet, and to form the remainder of the
opening of arching, as shown in Fig. 91.

This arrangement is not only less costly than an embankment of such
height, but has also the great advantage that any or all of the arches
are available for the passage of streams, rivers, roads, and
accommodation works.

The character of the work to be carried out in the construction of
bridges or viaducts over rivers or valleys must greatly depend upon
the description of materials at command. Where good building-stone is
plentiful, and the price of labour moderate, works of masonry should
be adopted as far as practicable. Brickwork is an excellent substitute
for masonry, provided that specially selected bricks are used for all
facework, or parts exposed to the weather. For water-washed piers and
abutments, the lower portion should be faced with good hard stone.

[Illustration: Fig. 92]

Bridges and viaducts consisting of arches of masonry or brickwork form
the most substantial and permanent works of construction for railway
purposes; once properly built, the expenditure on future maintenance
or repairs is merely nominal. For viaducts the span of the arching
must be regulated by the height of the viaduct. The greater the height
the larger the span. In one case 30-feet spans may be suitable,
whereas in another it may be more economical to introduce spans of 60
feet or more, and so reduce the number of lofty piers. From a cost
point of view there is, however, a limit to the span of arching, and,
except for special cases, where expenditure is of secondary
importance, large spans are very rarely adopted. Arches of large
spans, no doubt, have been built both in masonry and brickwork, and
have been a complete success in every way except expense.
Unfortunately, the quantity and weight of materials in arching, and
the corresponding cost, increase very rapidly as the span increases,       95
and for openings of more than 60 or 70 feet girder-work becomes much
cheaper than arching.

Figs. 92 and 93 are examples of viaducts having piers of masonry, with
girders to carry the roadway. In the one case the roadway is carried
on the bottom flange of the girders, and in the other on the top. The
latter arrangement affords greater facility for securely bracing the
girders together, while for the former it is claimed that the girders
form a massive parapet, which would serve as a protection in the event
of an engine or vehicles leaving the rails.

In the early days of railways, many large viaducts were constructed
having masonry piers, and timber trusses to carry the roadway. Much
ingenuity was displayed in designing the trusses, and in the
introduction of cast-iron joint-shoes and wrought-iron bracings. Many
of these wooden superstructures served well for several years, but
they were always exposed to the imminent risk of destruction from
fire, and however carefully the logs may have been selected, the decay
of the timber was only a question of time. The deterioration of one
piece was equivalent to the weakening of the entire truss, and the
renewal of any part was both difficult and costly. The shrinkage of
the timber, and the working at the joints, caused the trusses to
deflect considerably under a passing load, and although the actual
strength of the structure may not have been much impaired, the
creaking and depression had anything but a reassuring effect. Timber
superstructures for anything but small spans are rarely adopted now,
except for temporary works, or on lines abroad, where the transport on
girder-work would be very costly, and where good timber is very cheap
and abundant. Even in the latter case the wooden superstructure is
generally looked upon as a temporary expedient, to be replaced at no
very remote date with iron or steel girders, when the materials can be
conveyed over the entire completed line.

Figs. 94, 95, and 96 are sketches of three types of timber trusses as
constructed in viaducts of several spans.

[Illustration: Fig. 93]

There are many localities, especially abroad, where suitable stone is
most difficult to obtain, and very expensive to work and convey. In
such cases it is compulsory to use as little of it as possible, and to
resort to iron or steel both for the girders and a large portion of
the piers. The piers may be made of cast-iron, wrought-iron, or steel,     97
of suitable form and arrangement to ensure strength and stability. Not
only must the piers be strong enough to carry the weight that may be
brought upon them vertically, but they must have sufficient width of
base to ensure lateral steadiness. The design should admit of facility
of erection, with a minimum of scaffolding, and the pieces should be
of convenient length and weight for transport. The lower length of
river piers, or portion liable to be in contact with flood-water,
should be of solid masonry, to resist the action of the water, or of
any _débris_ brought down by the current. More than one fine
viaduct has been swept away for want of due attention to the latter
precaution.

Fig. 97 illustrates a type of pier composed of cast-iron columns, well
braced and stayed with wrought-iron. The ends of the columns and all
contact surfaces should be properly turned and faced by machinery to
ensure true and perfect joints, and the socketed ends should be turned
and bored to fit closely. The latter is important, and if not
carefully carried out, a slight sliding movement of the flanges may
take place, and throw undue strain on the bolts.

Fig. 98 shows a very similar pier, constructed entirely of
wrought-iron or steel.

Each of the above-described piers has a liberal amount of taper or
batter, both in the front and transverse elevation.

The size and number of the columns, and the dimensions of the braces
or stays, will depend upon the height of the pier and the weights and
strains to be sustained.

Many important and lofty viaducts have been erected on this principle
of iron piers springing from masonry foundations, more particularly
across deep rugged ravines abroad, where iron piers offered the only
practical, substantial means of dealing with what appeared otherwise
an impossibility.

[Illustration: Fig. 94, 95, 96, 101]

[Illustration: Fig. 97, 98]

[Illustration: Fig. 99]

[Illustration: Fig. 100]

Fig. 99 is a sketch of the Kinsua Viaduct on the Erie Railway, one of
the highest railway viaducts in the United States. In the transverse
elevation the piers have a large amount of taper; but in the front
elevation they are vertical, and of width to correspond to one of the
small spans of the main girder. This arrangement of long and wide base
gives great stability to the pier. The spans of the girders, which are
of the ordinary lattice type, are not large, being 61 feet for the
clear spans, and 38 feet 6 inches for those over the piers. The
principal interest is in the great height and simplicity of the piers.    102
The rail-level over the top of the pier is 301 feet above the level of
the water in the Kinsua stream. The width of this pier on the top is
10 feet (for single line), and the width at the bottom 103 feet.

Fig. 100 is a sketch of the Loa Viaduct on the Antofagasta Railway,
Bolivia, stated to be the highest railway viaduct in the world. The
arrangement of spans and piers is very similar to the Kinsua Viaduct.
The main spans are 80 feet, and the pier spans 32 feet. The width of
the pier on the top is 10 feet 6 inches (for single line), and the
width at the bottom of the highest pier is 106 feet 8 inches.

In contrasting these light iron piers with what would have been
required if constructed of masonry, an idea may be formed of the
enormous amount of material, labour, and time, which would have been
expended to erect the work in stone.

Before the principle of lofty iron piers had been thoroughly
developed, many high piers had been built of timber both at home and
abroad. More particularly was this the case in the United States of
America, where the presence of magnificent timber close to hand
offered special inducements for the use of wood. Like a mammoth
scaffolding, each pier was constructed with a most liberal supply of
material, judiciously selected and carefully put together, but the
danger of destruction by fire was ever present from the beginning.
Probably more timber piers and bridges have been destroyed by fire
than have been removed on account of natural decay.

One of the most notable of these timber-pier constructions was that of
the Old Portage Viaduct, on the Erie Railway, U.S.A. Fig. 101 is a
sketch of one or two of the piers. This viaduct was more than 800 feet
long, and 234 feet high from the bed of the river to the rail-level.
The spans were 50 feet each. Masonry piers were carried up to about 25
feet above the ordinary water-level of the river, and upon these the
timber superstructure was erected. Each timber pier consisted of three
complete sets of framework, securely connected together, and also well
stayed and braced to the adjoining piers. This viaduct was destroyed
by fire in 1875, and was reconstructed with piers and girders of iron.

Railway bridges over or under public roads of primary or secondary
importance must be constructed to the widths and heights prescribed
for such works in the fixed regulations of the country in which they      103
have to be built. As a rule, these road-bridges are simple and
inexpensive in character, except in towns, or in cases where the line
crosses the roads very obliquely, or where the road is situated at the
top of a deep cutting, or bottom of a high embankment. Away from towns
and out in the open country, permission is generally obtained to
divert the roads to a moderate extent, so as to obtain a more
favourable angle and height for the bridge; but in towns, where the
roads become streets, sometimes of great width, with houses and shops
on each side, little or no diversion can be allowed.

A railway passing through a portion of a densely populated town must
deal with the streets as they exist, as any great alteration in their
course or continuity would involve a large destruction of property.
With careful laying out it is possible to obtain favourable crossings
for many of the streets, but a number of others must be crossed
obliquely, and these oblique crossings very frequently result in a
span twice the width, or even more, of what would be necessary to
cross the street on the square. Bridge-work in towns is more costly
than in the country, as a higher class of work is demanded, more
finish or dressed work in the masonry or brickwork, and more
ornamentation in the screens and parapets in connection with the iron
girder-work. The work itself has to be carried on in a confined
locality, with limited space for materials and appliances, and where
the thoroughfare must be kept open.

Where the height is sufficient, and suitable materials readily
obtained, it is preferable to adopt an arch bridge, as being of a much
more permanent character than girders.

Fig. 102 is an example of an ordinary over-line arch bridge to carry a
public road over a double line of railway in a cutting of moderate
depth.

Fig. 103 shows a somewhat similar over-line arch bridge, but its
height from rail to road-level being greater, side arches are
introduced in preference to long heavy wing walls.

Fig. 104 shows an over-line arch bridge in a rock cutting. In this
case, by increasing the span and forming the springing bed in the
solid rock, the masonry of abutments and wing walls may be reduced to
a minimum.

Fig. 105 is a sketch of an ordinary under-line arch bridge to carry a
railway over a public road in an embankment of moderate height.

[Illustration: Fig. 102, 128, 129, 130]

[Illustration: Fig. 103]

[Illustration: Fig. 104]

[Illustration: Fig. 105]

[Illustration: Fig. 106]

[Illustration: Fig. 107]

Fig. 106 shows a similar under-line bridge, but with curved instead of    110
straight wing walls.

Fig. 107 is an example of an under-line arch bridge in a rather high
embankment, and where side arches have been adopted instead of long
wing walls.

The above six types are equally applicable for private roads crossing
the railway, but, as previously mentioned, a lesser width and headway
will be accepted for under-line bridges for private or occupation
roads, than for public roads. For the over-line bridges, however, the
width and headway will be regulated by the number of lines and
standard height of the railway.

When these arch bridges have to be built on the skew to suit an
oblique crossing of the road, extra care will be necessary in setting
out the work, and marking on the centering the spiral courses of the
arching.

Arch bridges may be built of masonwork or brickwork, or a combination
of the two. If the available quarries do not yield good flat bedded
stones readily worked, it is better, where possible, to use strong
hard bricks for the arching, and utilize the stone for the remainder
of the work.

Although arching undoubtedly forms the most durable type of
bridgework, numbers of cases occur where the available height or space
between rail-level and road-level is too small, or the cost of masonry
and brickwork too great, to admit of anything but girder-work.
Detailed sketches of some of the many forms of girder bridges are
given in Figs. 132 to 153, illustrating various systems of roadways
and parapets. In some instances the main girders are made sufficiently
deep to serve as parapets, while in others a shallower girder has been
adopted, on top of which has been placed a light cast-iron parapet
composed either of close plate-work or of ornamental open railings.
The open ironwork parapet has a good appearance, but as a screen is
not so efficient as the close cast-iron plates.

In addition to the bridges required for the regular public roads, it
is usually necessary to construct a certain number of occupation or
private road bridges over and under the line to accommodate portions
of estates and large properties intersected or severed by the railway,
and which would be inadequately provided for by ordinary gate
crossings on the level. The position and description of these
occupation bridges is generally matter of private arrangement. The
bridges will be somewhat similar in character to the public road          111
bridges, but of much less width for the roadway. Those over the
railway must have the standard span and height adopted as a minimum
for the other over-line bridges, and those under the railway must have
the full width on the top for the lines of rails, but will have less
width between the abutments for the roadway.


Foundations.--So much depends upon the soundness and security of the
foundations of any bridge, viaduct, or large building, that it would
be almost impossible to devote too much care to the selection and
treatment. Unless the foundation be firm, the entire structure will be
exposed to the risk of failure, either in subsidence of masonry,
giving way of arches, or depression of girders. A small matter
overlooked during the construction of this part of the work will be
most difficult to correct or adjust afterwards.

The insistent weight of all structures built of masonry or brickwork
will cause the mass to settle to a certain extent, according as the
joints of mortar or cement become compressed by the number of
superincumbent courses. In a similar manner the gravel and clay of a
foundation will compress more or less according to its compactness and
the weight of the structure. No inconvenience will, however, arise if
the settlement or compression be uniform throughout the entire area.

In ordinary average, dry, solid ground, a good foundation can usually
be obtained at a moderate depth. The removal of a few feet of the
surface layers will generally lead to a good hard stratum of natural
material sufficiently firm to carry the abutments and piers of railway
bridges and viaducts. Two or more footings are usually adopted so as
to distribute the weight over an increased area, as shown in Fig. 108.

Where the weight to be carried is considerable, it is better to
increase the number of the footings, and give them a smaller
projection, as in Fig. 109, rather than have a lesser number and
greater projection, as in Fig. 108. There is greater liability of
fracture of the material in the latter than in the former.

Care must be taken to distinguish between made ground and natural
ground. Hollows which have been filled in must not be relied upon to
sustain heavy weights; the material may have been consolidating for
years, but it is safer to cut through it and found upon the natural
stratum beneath.

[Illustration: Fig. 109, 108, 110, 111, 124, 113, 114, 115, 125]

Soils of a clayey nature must be dealt with very cautiously. If the       113
ground be fairly level, and the material firm, a solid foundation may
be obtained, but the excavated portion should be covered up as quickly
as possible to prevent any decomposing action taking place upon
exposure to the open air. The expansive nature of some clays must be
carefully kept in view, so as to guard against any disturbance in the
finished foundation. There are some descriptions of shale which when
first opened out appear to have the solidity of hard rock, and yet,
after a few days’ exposure to the atmosphere, are changed to the
consistency of soft mud.

Sand, being composed of such small particles, is almost incompressible,
and makes an excellent foundation so long as it can be retained in its
position. Little or no settlement will take place if the sand remains
undisturbed, but so soon as it comes under the influence of running
springs, or underground drainage, the fine particles of the sand will
be gradually but surely carried away with the water, and the entire
foundation be undermined. The opening out of a neighbouring
excavation, or the carrying out of some low-level drainage, would
endanger a construction which otherwise would be solid and permanent.

In many cases of soft ground, more particularly abroad, sand piles
have been adopted and have given very good results. The system is
carried out by first driving a large wooden pile down through the soft
material into the more solid stratum below. The timber pile is then
carefully withdrawn and the cavity filled with clean sand. The number
and distance apart of these sand piles will depend upon the nature of
the ground and description and weight of structure to be carried.

Clean, compact gravel is one of the best materials to build upon,
being almost incompressible and quite unaffected by exposure to the
atmosphere. It is easily excavated and levelled off to the surface
required.

A foundation of rock may be considered in the abstract as the most
solid base to be obtained, but it must be treated judiciously, and a
proper surface secured. The outer portion of many descriptions of rock
consists of blocks or layers of stone partially or entirely separated
from the main bed, and these, lying in a loose condition, are
deceptive and treacherous as a foundation base. The exposed rock
should be carefully examined, and all detached or outlying pieces or
layers removed before placing any foundation course. Special care must
be paid to all shelving rock, and a level seating cut into it for the     114
entire width of the foundation, as shown in Fig. 110.

A thick bed of concrete, as in Fig. 109, makes an excellent foundation
course. When firmly set it becomes one solid massive base from end to
end, and prevents the yielding or dropping of masonry at any
intermediate points.

There are many places in soft, wet ground where instead of attempting
to excavate all the soft material down to a harder stratum, it is
better to adopt timber pile foundations, as shown in Fig. 111. The
size of the piles and their distance from centre to centre must be
regulated by the description of material into which they have to be
driven and the weight they have to sustain. Double waling pieces
should be properly checked and bolted on to the heads of the piles,
and trimmed or levelled off to receive a double floor of thick planks.
The spaces round the heads of piles and walings should be filled in
and levelled up to under side of flooring, with cement concrete.

[Illustration: Fig. 112]

For bridges of moderate span, over soft ground or over shallow fresh
water, strong cast-iron screw piles can be adopted with great
advantage. Fig. 112 shows a very usual form of screw pile, made with
an external screw at the lower end and with a sharp cutting edge to
facilitate penetration into the ground. The upper portions are made in
suitable lengths, and all to one pattern and template, for convenience
in carrying out the work. The screwing into the ground is generally
effected by means of a capstan or cross-head fixed to the top of the
first working length of pile, and which is pulled or turned round by
ropes worked from stationary windlasses. In some cases long bars or
levers are attached in radiating positions to the capstan-head, and a
number of men are employed to walk round and round, pushing the
levers, and in this way screwing the pile into the ground. As the pile
goes down the capstan-head has to be removed, and additional lengths
bolted on, until the pile enters a solid stratum, or is considered
deep enough for the duty it has to perform. The last or top length has
generally to be cast to a special length to bring the work up to the
exact height to receive the girders. The core of excavated material
passes up into the interior of the pile, and in some cases becomes so
compressed or tight as to require the use of an internal augur to
remove a portion of it to enable the screwing to proceed. The pile
shown in Fig. 112 is one of a number which were successfully screwed
into the ground to depths varying from 42 to 48 feet. A toothed or        116
serrated edge, as in Fig. 113, is sometimes given to the lower edge
for screw piles which have to cut their way through a hard stratum.

All bolting flanges should be accurately turned and fitted to ensure
close, parallel surfaces when bolted together.

The joint shown at A, Fig. 112, is one the writer has used to a
large extent for the bolting flanges of cast-iron screw piles and
cylinders. It is very simple in form, readily coated with white lead
to ensure a water-tight joint, and as the upper length is practically
recessed, or let into the lower length, the exact continuity of the
different castings is secured.

Solid screw piles of wrought-iron or steel, similar to Fig. 114, are
used for some descriptions of work. These are generally made in long
lengths, in sizes varying from 4 to 8 inches in diameter, and with
screw blades of wrought-iron or cast-iron fixed in the most secure
manner to resist the strain produced when screwing into the ground.
The couplings for these solid piles must be very carefully made, all
contact surfaces truly faced and fitted, bolts turned, and bolt-holes
drilled.

Fig. 115 is a sketch of a hollow cylindrical water-jet pile, which has
been used successfully in cases of light sand. The lower end of the
pile is made externally in the form of a solid disc, terminating in a
conical point, having an aperture in the centre to correspond to the
water-jet. To the top of the pile is secured a tight-fitting cover
through which a tube passes from a force pump. Water at high pressure
is pumped into the tube, and as it forces its way out through the
conical point the sand is stirred up and loosened, and thus allows the
pile to descend. When the pile has been lowered to a sufficient depth
the pumps and tube are removed, and the sand settles down into its
former compact condition.

Great care must be used with the first two or three lengths of any
screw pile to ensure the pile taking a correct or true vertical
position. Each series of screw piles should be properly braced
together to obtain stability under moving loads.

[Illustration: Fig. 116]

[Illustration: Fig. 117]

Hollow cylinders of cast-iron, wrought-iron, or steel form most
efficient foundations or piers for large bridges over soft ground or
fresh water of considerable depth. Made open at the bottom, and
constructed of complete rings, or, if of large diameter, of rings
built up in segments and securely attached together with water-tight      119
joints, the cylinder is placed in its proper position on the ground or
lowered into the water preparatory to sinking. The lower length is
made with a sharp cutting edge to facilitate penetration. By
excavating and removing the material round the cutting edge and base
inside the lower length, the cylinder descends gradually either from
its own weight or by assisted weights, and length after length is
added until it is sunk to the depth required. The excavated material
is filled into buckets and hoisted to the surface by a winch fixed on
the top length. When sinking in water the working top of the cylinder
is always kept at a suitable height above the water for convenience in
removal of the earth or clay from the interior to barges or gangways
alongside.

Some strata are more favourable for cylinder sinking than others.
Material of a strong clayey nature admits but a small amount of water
into the excavation, and a moderate-sized pump will keep the working
fairly dry until considerable depth has been reached. Some other
materials are so open that the water cannot be kept down with ordinary
pumps, and the cylinders can then only be lowered by the pneumatic
process. This process has been carried out in two methods, one of them
on the _vacuum_ principle, and the other by air pressure, or, as it is
termed, the _plenum_ system. With the former method the cylinder is
placed in position, and an air-tight cap, through which a pipe passes,
is secured on the top. Powerful air-pumps are then set to work, and
the partial vacuum thus created in the interior causes the material
round the cutting edge and base to be loosened and drawn into the
cylinder, the cylinder at the same time going down or sinking by its
own weight, or assisted, if necessary, by added weights. The cap is
then taken off, and the material removed from the interior, the
operation of exhausting and emptying the interior being repeated until
the cylinder is sunk to its proper depth. This method has been found
to work well in strata which contained a large proportion of clay to
assist in excluding the air and water, but was not nearly so
successful when applied to material containing stones and large
boulders.

The _plenum_ process is based on the principle of the diving-bell, the
water being prevented from entering at the bottom by keeping the
cylinder full of compressed air. An air-chamber, or _air-lock_, with
perfectly air-tight joints, is securely fixed to the top or upper         120
working length of the cylinder, and no access can be obtained to the
interior of the cylinder without passing through this air-lock, which
has one lower door or valve opening into the cylinder, and an upper
door opening out into the open air. Temporary inside staging is formed
by putting planks across from flange to flange, and placing short
ladders on these landings for the use of workmen descending or
ascending. The excavated material is hoisted by a winch, generally
placed on the landing just under the air-lock. The air-pump is placed
in some convenient position outside, near at hand, the pressure-pipe
passing through the air-lock into the interior of the cylinder. Air is
forced into the cylinder to a pressure sufficient to drive out and
keep out the water from the interior, and allow the workmen free
access for excavating the material round the cutting edge and base of
cylinder. The amount of pressure required will depend upon the depth
of the working below the level of the water alongside. Men accustomed
to the process can work without much inconvenience under a pressure of
20 to 22 pounds per square inch, equal to a depth of 45 to 50 feet;
but when the pressure exceeds 25 pounds, the duty becomes very trying,
and is attended with considerable risk. Instances are recorded of men
working at depths of 105 and 110 feet, necessitating a pressure of
over 45 pounds per square inch; but it is very questionable whether
the men exposed to such a severe ordeal were not permanently affected,
if some of them did not actually succumb.

It will sometimes occur that, after sinking through soft porous strata
to a considerable depth, a layer of clayey material is penetrated
sufficiently retentive to keep out the water and permit of the removal
of the air-lock and the completion of the sinking as an open-top
cylinder.

When working on the _plenum_ system everything must pass through the
air-lock, both materials and men. The excavated material is hoisted up
to the level of the air-lock, the upper and lower doors of which must
be closed, and the pressure inside the air-lock brought to the same as
that inside the cylinder by means of a regulating valve. The lower
door is then opened to admit the excavated material, and then closed
again to cut off all communication with the interior of the cylinder.
The upper door is then opened, and the material hoisted out into the
open air. The same process has to be adopted for the egress of the
workmen, and the reverse arrangement for the ingress of men and           121
materials. The shape and dimensions of the air-lock may be varied
according to circumstances, but the principle will remain the same.

When the cylinder has been lowered to what is considered a sufficient
depth, it is usually loaded with a certain amount of dead weight in
the shape of old iron or other convenient material, and allowed to
remain loaded for some days to ascertain if it will sink any further.
Should this test be found satisfactory, the dead weight is removed,
and the interior of the cylinder pumped dry and carefully filled with
good cement concrete.

Cylinders for foundations are generally made circular in section, that
form being the most convenient for turning and facing the
flange-joints. They can, however, be made oval in section, or of any
section that may be found most suitable for the work required. Figs.
116 and 117 give the particulars of a double-line railway bridge
carried on cylinder piers across a river. The detail sketches explain
the form of cutting edge, flange joint, and method of bracing. This
bridge is one that was reconstructed and widened from a single-line to
a double-line bridge. Traffic was carried over on one line while the
second line was being erected, hence the reason why one strong central
girder was not adopted.

Cylinders of 7 feet diameter and upwards are sometimes filled with
concrete in the lower portion, on which is built either a circular
lining or a solid mass of masonry or brickwork up to the level of the
girder-blocks. In some cases the cylinders proper, together with their
concrete filling, terminate a little above the water-level, and upon
these foundations are erected strong cast-iron columns, plain or
ornamented in design, to carry the girders and roadway. The cylinder
itself is generally considered merely as a casing or medium for
obtaining a foundation, the weight of the superstructure being carried
on the internal filling or lining.

Caissons constructed of plates of wrought-iron or steel are much used
for the foundations of large piers in deep water. Practically they may
be considered as cylinders on a large scale, with the difference that
whereas cylinders are generally continued up to the under side of the
girders of the superstructure, caissons are only carried up to a short
distance above the water-level. A caisson forms a strong water-tight
iron cofferdam, from which the water can be excluded, and a masonry or    122
brickwork pier constructed inside. It may be made all in one piece to
correspond to the form of the pier, or in separate pieces to form one
whole, each being sunk independent of the other, and connected
together afterwards. Being built up of plates cut to the proper size
and shape, it is a very simple matter to rivet on additional tiers of
plates as the caisson is lowered deeper and deeper into the bed of the
river. The lower length is made with a cutting edge to penetrate the
ground; the exterior is made without any projection larger than the
rivet heads, and the interior is strengthened with T-irons or double
L-irons at the joints, and strong cross-bracing to resist the
pressure of the water. About 7 or 8 feet above the cutting edge a
strongly framed iron floor is riveted to the vertical sides, and
strengthened by plate-iron under-brackets placed at short distances.
The excavators work in the space below the floor, and the excavated
material is passed up through openings formed in the floor at
convenient points to suit the working. The methods of lowering a
caisson are the same as for lowering a cylinder. If the pneumatic
system has to be adopted, then two or more air-tight tubes of liberal
dimensions (say 5 to 8 feet diameter), according to the size of the
caisson, must be attached to the floor, and on the top of each of
these tubes air-locks must be secured for the removal of men and
materials. The masonry or brickwork of the pier is built upon the iron
floor, and a portion of this building work is usually carried on
during the sinking of the caisson to obtain weight to assist in the
lowering. When down to the proper depth, the space below the floor is
properly cleared of _débris_ and water, and then carefully filled in
with cement concrete.

Some caissons are made with vertical sides throughout their entire
height; others have an outward taper for 15 or 20 feet on the lower
end. The former are not only simpler in construction, but are more
easily kept in a vertical position during the sinking. Caissons are
usually put together in some convenient place near the edge of the
water, and then conveyed on pontoons to the sites of the piers. Great
care is required in lowering them into position in the bed of the
river, and guide-piles, guy-chains, and other appliances are
frequently necessary to keep them vertical during the sinking.

The form, dimensions, thickness of plates, cross-bracing, and general
arrangement will depend upon the size and depth of the pier to be         123
constructed. Caissons for heavy work on difficult or treacherous
ground require great care, not only in their construction, but also in
placing them in exact position, and in sinking them correctly to their
proper depth. A tilted caisson is a most difficult subject to handle,
and entails heavy expenditure to restore it to a true vertical
position. By making careful borings, the engineer can ascertain very
closely the depth to which the caisson will have to be lowered to
obtain a good firm foundation. With this information the caisson can
be so constructed that the upper portion, termed the temporary
caisson, commencing a few feet above the bed of the river, can be
detached, and removed at the completion of the work from the lower or
permanent portion sunk below the ground line.

Fig. 118 gives sketches of a wrought-iron plate-caisson applied to a
deep-water river pier, and lowered to its full depth by the pneumatic
process; dotted lines show the air-tubes through which the excavated
material is hoisted and emptied into barges alongside.

Many large and important pier foundations have been constructed on the
system of brick cylinders or wells, particularly in India, where the
foundations for large river viaducts have to be carried down to great
depths through thick deposits of soft material. These wells are built
upon V-shaped curbs to facilitate the penetration when sinking. Fig.
119 is a section of a well with a wrought-iron curb, and Fig. 120 is a
similar well with a wooden curb. The wrought-iron curb is made in
segments for convenience of transport, the pieces forming the complete
ring being bolted or riveted together at the site of the foundations.
The wooden curb is composed of several thick layers of hard wood
planking cut to the proper shape, and laid with broken joints, the
whole being bound together with suitable bolts and spikes. In some
cases the lower or cutting edge of the wooden curb is strengthened or
protected by a sheathing of wrought-iron plates.

[Illustration: Fig. 118]

[Illustration: Fig. 119, 120, 121, 122, 123]

Well foundations are usually put in when the rivers are at their
lowest, and reduced to a few small channels in the great width of
dried-up river bed. This condition enables the greater portion of the
curbs to be conveniently and accurately placed in position on dry
ground, or on ground which, although soft and muddy, is not covered
with water. Should the site of one of the wells occur in one of the
small channels, the stream can be diverted to one side, and a small       126
artificial island made to receive the curb above water-level. When a
curb is fairly fixed in position, the work of building the brick well
can be commenced. With the wrought-iron curb the triangular cavity
between the vertical plate and sloping plate must be filled with
concrete to form a level base for the first course of brickwork. The
wooden curb being composed of horizontal layers of timber, is ready to
receive the brickwork without further preparation. To strengthen and
keep the brickwork firmly tied together, strong wrought-iron vertical
tie-rods, 1¼ or 1½ inch in diameter, are generally built into the
work--as shown in the sketches--at distances about four feet apart.
The lower end of the bottom tier of tie-rods is secured to the curb,
and the upper end passed through a strong wrought-iron plate-ring,
which is continuous all round the brickwork. A long deep nut is
screwed down over the top or screwed end of tie-rod until the
plate-ring is down tight on the brickwork. The tightening nuts are
made sufficiently deep to receive the lower ends of a second series of
vertical tie-rods, which in like manner pass through another
wrought-iron plate-ring on the next section of brick well, and the
same arrangement is continued for the full height of the well. The
lengths of the tie-rods will depend upon the lengths of the section of
brickwork to be built at a time, and may vary from 10 to 15 feet.

As the work of building proceeds the curb and brick well will sink
gradually into the ground, and down to a certain depth, varying
according to the material of the river bed, the weight of the brick
well itself will effect the penetration and lowering. Beyond this
depth the lowering must be done by scooping or dredging the material
from the inside of the well, and placing heavy weights of old railway
iron or other convenient masses on the top. When one section or length
of well has been sunk down, then another set of tie-rods are inserted
into the deep nuts, and another section of brickwork commenced. The
operation of lowering is rather tedious, as all the weights have to be
hoisted up on to the top of the length in hand, and piled so as to
leave space for lifting out the material dredged from the interior;
and then, when the length has been lowered, all the weights must be
removed before the brickwork can be resumed on another length. Where
the river bed consists of soft material, the excavation inside the
well can generally be effected by suitable dredges or scoops worked       127
from the surface or top of brickwork. Should trees or other
obstructive masses be met with embedded in the strata, it will be
necessary to employ divers to remove them piecemeal out of the way of
the curb.

When the brick well has been lowered down to the full depth, and is
thoroughly bedded in a stratum of strong material, the test weights
should be left on for some time to ascertain if there is any further
sinking. After all the weights have been removed the bottom of the
well can be dredged out clean, and the interior filled in with
concrete to such height as may be considered necessary.

Brick wells must be watched carefully to ensure that they sink down in
a perfectly vertical position. Any inclination away from the
perpendicular must be corrected at once by means of guys and struts,
the same as in sinking iron cylinders. The principal difficulty will
be with the first 20 or 25 feet.

The diameter of the well will depend upon the weight it has to carry,
and its height from river bed to under side of girders. The wells may
be either circular or polygonal in section, and built singly or in
pairs, as shown in sketches (Fig. 121).

Many piers and abutments of bridges in shallow or moderately deep
water are built by means of coffer-dams of timber and clay puddle. The
coffer-dam forms a water-tight wall round the site of the foundation,
from which the water is pumped out, and the excavation carried down to
the depth required. In very shallow water it is sometimes sufficient
to drive only a single row of piles, and form a bank of good clay
puddle on the outside, as shown in Fig. 122. In deep water it is
necessary to drive a double row of piles, 3 or 4 or more feet apart,
and fill in the space between with clay puddle, as shown in Fig. 123.
The piles for coffer-dam work should be carefully selected, of good
timber straight, and correctly sawn on the contact faces. Guide-piles
are first driven in proper line and position round the intended
foundation. To these strong horizontal double waling pieces are
securely bolted, one on each side of the guide-pile, one pair near the
top, and the other pair as low down as can be placed. The sheeting
piles, which are lowered down between the horizontal waling or guiding
pieces, are driven as close to one another as possible, being assisted
in doing so by the sheet-pile shoe, shown on Fig. 124, which is made
not with a point like an ordinary pile shoe (Fig. 125), but with a        128
cutting edge slightly inclined, so that in driving the tendency of the
pile is to drift towards the pile previously driven. Sometimes the
outer row of piles consists of whole balks, and the inner row of half
balks; the size of the piles must, however, be regulated by the depth
and current of the water. When both rows of piles have been completed,
the space between should be dredged out, and then filled with
carefully prepared clay puddle. To enable the puddle to adapt itself
thoroughly to the wooden sides, it is desirable to remove the inside
walings after all the piles are driven, as any internal projections
interfere with the proper punning and settling of the puddle. The
swelling of the puddled clay has a tendency to force apart the two
rows of piles, and to counteract this as much as possible, iron
tie-rods should be passed through from side to side every few feet,
and screwed up against large washers placed on the outside of the
outer walings. Strong struts or cross-bracing of timber must be placed
from side to side inside the coffer-dam to resist the pressure of the
water in the river. This cross-bracing can be removed gradually as the
work of building progresses upwards, and be replaced with short struts
wedged in against the sides of the finished courses.

In cases where the ground is soft, and when it is not considered
prudent to excavate the foundations deeper for fear of disturbing the
stability of the coffer-dam piles, rows of large, square bearing-piles
may be driven in the floor of the foundation, as shown in Fig. 111.
The tops of these bearing-piles must all be sawn off to the same
level, and a platform of strong double planking securely fixed to the
piles to receive the foundation course of concrete, masonry, or
brickwork. The spaces around the tops of the piles and the under side
of the timber platform should be filled in with good cement concrete.

The interior of the coffer-dam is kept dry by constant pumping, either
by hand pumps or steam pumps, according to the volume of water finding
its way into the foundations. When the finished pier or abutment has
been carried up above the river water-level, the coffer-dam is no
longer required, and may be removed. Sometimes, to save the timber,
the piles are drawn by means of strong tackle fitted up for the
purpose; but in doing this there is considerable risk of disturbance
to the foundations, and it is better to leave the piles in the ground
and employ divers to cut off the tops a little above the bed of the       129
river.

In preparing the design for a large foundation it is absolutely
necessary to first ascertain by careful borings the description of
material upon which that foundation must be placed, so as to
proportion the area of bearing surface to the weight to be sustained.
Some materials will naturally carry more weight than others, and
although the engineer cannot always select the material he would
prefer, he can, however, control the superficial area of the
foundations. Much valuable information has been obtained both from
experiments and from comparisons of actual practice, and the following
memoranda may be useful for reference, as indicating the pressures per
superficial foot which may be safely put on various materials:--

     Moderately stiff clay                      2½ tons.
     Chalk                                      4   ”
     Solid blue clay                            5   ”
     Compact gravel and close sand              6   ”
     Solid rock                                12   ”

Doubtless the above weights have been exceeded in many cases, but it
is better to be on the safe side, and leave a good margin for
stability.

Large subaqueous foundations for heavy piers and abutments are costly
and tedious, and especially so when the pneumatic process has to be
adopted. Special appliances and well-trained, experienced workmen are
requisite, and if all the men and materials have to pass through the
air-locks, the progress of the work must necessarily be slow. When the
foundations have been completed up to the level of the water, the
construction can be pushed on more rapidly, as the work of
scaffolding, hoisting, and building, can all be carried on in the open
air.

Amongst the very many types of arch-work and girder-work adopted for
railway purposes, the following examples from actual practice may be
useful for reference:--

[Illustration: Fig. 126, 127]

Fig. 126 represents small 24-foot span, low viaduct arching suitable
for a line passing through towns or villages, where ground is valuable
and the area to be covered must be kept as small as possible. The
arches may be utilized for stables, stores, or roads of communication
between the lands and properties intersected by the railway. The
segmental form gives a better headway underneath than the
semicircular, besides containing less material in the arching proper,
and requiring a smaller amount of centering. Every precaution should      131
be taken to prevent water percolating through any portion of the
arching, or haunching, and a thick layer of good asphalte should be
placed over the entire upper surface, and carried well up the lower
portion of the parapet walls, as shown on the sketch. The cast-iron
pipes with rose heads form a very efficient means of taking away the
rain-water which filters through the ballast and filling. The pipes
should be carried down in chases, or recesses, built in the fronts of
the piers, to protect them as much as possible from injury in the
yards below. Rose heads, pierced with holes, and surrounded with small
stones hand-laid, serve well to conduct the water into the pipes.
Where the arching is of considerable length, recesses or refuges for
the platelayers may be obtained by substituting a short length of
cast-iron-plate parapet, instead of the stone or brick parapet, over
some of the piers, as indicated in the sketch.

Fig. 127 shows a similar description of arching for spans of 30 feet.
The above two examples represent plain substantial work, but if
circumstances warrant more external finish, this can readily be added
without interfering with the general arrangement. In a similar manner,
if considered preferable, the arches may be made semicircular or
elliptical.

In the sketches shown of the arched over-line and under-line bridges,
the arching and coping of parapets are in brick, and the remainder of
the work in stone. In very many cases brick will be found cheaper and
more expeditious for arching than stone, unless the quarries turn out
stone in blocks which can be conveniently trimmed for arching. All
bricks used for arch-work should be hard and well burnt, and special
care should be taken in the selection of those to form the under-side
course, which will be exposed to the atmosphere. For moderate spans
arches have been successfully constructed of concrete. For this
description of work the materials should be carefully gauged and mixed
together, and the finished work should be allowed to stand some time
on the centres to allow the concrete to become thoroughly set.

[Illustration: Fig. 131]

In Fig. 102, the cutting being deep, almost up to the level of the
public road, the foundations of the wing walls are built in steps,
resulting in a minimum of masonry below the finished ground line.
Where the cutting is shallow, and the public road has to be brought up
to the bridge on an embanked approach, the greater portion of the wing    133
walls will have to be built up from the solid or original ground, and
there will be a large amount of masonry below the finished ground
line, as indicated in Fig. 128.

In some cases of over-line bridges it is necessary to curve the wing
walls to correspond to the road which turns off to the right or left
after crossing the railway, as shown in Fig. 129; or the wing walls
may have to form two separate curves where the road branches off in
two directions after leaving the bridge, as shown in Fig. 130.

Fig. 131 shows plan, elevation, and cross-section of an under-line
arch bridge, considerably on the skew, carrying a railway over a
river. The wing walls are curved, and very similar in type to some of
those in preceding examples. The river bed and ground alongside being
of solid rock, good foundations were obtained at a very moderate cost.

On many railways constructed in the beginning as single lines only,
the over-line bridges have been built for double line. The additional
cost in the outset has been small, compared with the great expenditure
which would be incurred afterwards in reconstructing the bridges to
suit a double line.

The general arrangement of abutments and wing walls shown in the
foregoing examples will apply to similar classes of bridges where
girder-work is adopted instead of arching.

There are many ways of forming the floor or deck of a girder bridge
intended to carry a railway over a road or stream. In some cases it
will be imperative to have a thoroughly water-tight floor to prevent
rain-water percolating through to the roadway below; while in others,
such as bridges over streams, and secondary roads, this special
provision will not be necessary, and a lighter and more economical
floorway can be adopted. A strong wrought-iron or steel-plate
flooring, with its corresponding filling and ballasting, means not
only so much additional cost in the flooring proper, but also so much
additional dead weight to be carried by the main girders.

[Illustration: Fig. 132, 133, 134, 135, 136, 141]

Fig. 132 is a sketch of rolled joist-iron I-girders and timber floor
frequently adopted for small farm roads and cattle creeps of 10 or 12
feet span. A beam of timber is fitted in between the two rolled
joist-irons, and the three pieces securely fastened together with
strong iron bolts placed about 3 feet apart. These small compound
girders rest on bearing-plates of wrought or cast iron, and are held      135
together and to gauge by tie-rods, as shown. The rails are spiked or
bolted down on to the timber beams, and the flooring formed of strong
planking.

Fig. 133 shows an arrangement of plate girders for a 16-foot opening
over a stream. The girders are placed immediately under the rails, and
are tied together by plate-iron cross-bracing the same depth as the
main girders. The flooring consists of 4-inch planking laid with
¾-inch spaces, on which are laid longitudinal rail-bearers 14 inches
wide by 7 inches thick.

Fig. 134 is a sketch of a somewhat similar arrangement for a
lattice-girder bridge, 45 feet span, carrying a single line of railway
over a river. The main girders are tied together by lattice-work
cross-bracing. The floorway consists of 5-inch planking, laid with
¾-inch spaces, on which is placed the 14 feet by 7 feet longitudinal
rail-bearers. Plate-iron outside brackets are riveted to the main
girders to carry the ends of the planking and light tube-iron parapet.

Fig. 135 illustrates an example of trough girders, constructed to
carry a double-line railway over a country road 25 feet wide, where
the space from under side of girder to rail-level is small. The
girders are constructed in pairs, with short, shallow cross-girders at
3 feet 6 inch centres, riveted in between them to carry longitudinal
timbers on which the rails are laid. Bottom plates, 5/8 inch thick,
unite the two girders for the length of their bearing on the
abutments, and a similar plate, 9 inches wide, unites them at the
centre; the remainder of the span is left open to prevent the lodgment
of rain-water. Three strong tie-rods are placed to keep the girders to
gauge. Curved wrought-iron ballast-plates are used between the
running-rails, and plank flooring forms the rest of the covering.

[Illustration: Fig. 137]

Fig. 136 is a sketch of a plate-girder bridge over a country road 28
feet wide, with the load carried on the lower flange of girder. Three
main girders carry the double line of railway, the centre one having
double the strength of each of the outside girders. On the top of the
cross-girders, strong angle irons are riveted to serve as guides and
supports for the longitudinal timbers which carry the rails. Every
third cross-girder has raised ends to give increased lateral stability
to the main girders. A close cast-iron plate parapet forms a screen to
the roadway. Wrought-iron ballast-plates are used between the
running-rails, and the remainder of the flooring is of timber.

Fig. 137 gives the particulars of one 60-foot span of a viaduct           137
carrying a double line of railway over tidal water. The main girders
are placed one under each line of rails, and all the four are strongly
tied together by lattice-work bracing the full depth of the girders.
The outside footpaths for the platelayers are carried on strong
brackets, riveted to the main girders. Longitudinal timbers, coped
with angle iron, are placed as outside guards, alongside each rail,
for the full length of the viaduct. Wrought-iron ballast-plates are
placed between the running-rails. The remainder of the footways
consist of timber planking, laid with half-inch spaces, and covered
with a layer of small pebbles as a protection against fire.

Fig. 138 shows a very similar arrangement in a viaduct carrying a
single line of railway across a river. The two main lattice
girders--66 feet span--are placed at 9-foot centres, to obtain greater
stability. The cross-girders are extended to carry the outside
footpaths and handrailing. Outside guards are placed alongside each
rail as in the preceding example. Wrought-iron ballast-plates are
fixed all along between the running-rails, and timber planking used
for the rest of the floorway.

Fig. 139 gives cross-section of a lattice-girder bridge, 82 feet span,
carrying a single line of railway over a river, with the load carried
on the lower flange. The cross-girders are placed at 4 feet 3 inch
centres. Wrought-iron ballast-plates compose the floorway between the
rails, and timber planking covers the rest of the bridge. Plate
diaphragms, or stiffeners, of the form shown at A, A, A, A,
are riveted to the main girders at five places in their length.

Fig. 140 shows cross-section of a lattice-girder bridge of 200 feet
span, carrying a single line of railway over a river, the load being
placed on the lower flange. The floorway consists of plate-iron
cross-girders, spaced at 4-foot centres, on which are placed the
longitudinal rail-bearers and planking, the latter being covered with
a layer of clean pebbles for the width between the running-rails. As
the depth of the main girders was sufficient to admit of overhead
bracing, strong plate-iron diaphragms, of the form shown on the
sketch, were riveted to the main girders at every 50 feet. These
diaphragms thoroughly brace the two girders together, and effectually
prevent any tendency to side-canting, at the same time imparting an
effective appearance to the bridge.

[Illustration: Fig. 138, 139, 143]

Fig. 141 shows cross-section of a plate-girder bridge, of 36 feet         139
span, carrying six lines of way across a street. Strong plated
cross-girder bracing, at 4 feet 8¼ inch centres, is riveted to the
main girders, and the top is covered with old Barlow rails, 12 inches
wide, and weighing 90 lbs. per lineal yard. A layer of asphalte, about
1½ inches thick, is carefully laid all over the upper surface of these
rails to make a thoroughly water-tight floor. Clean gravel is placed
on the top, on which are laid the sleepers and rails of the permanent
way. Rain-water passes through the gravel into the hollows of the
Barlow rails, and finds its way into suitable drains provided at each
abutment. This arrangement not only prevents the falling of drip-water
into the street below, but permits of the alterations of the lines of
way, or putting in of cross-over roads on the surface above. The
outside main girders are made deeper, and are surmounted by close
cast-iron parapets.

Fig. 142 gives the particulars of a three-span plate-girder bridge,
constructed to carry a double line of railway over two other railways
and a canal, the load being placed on the lower flange. Two main
girders are used for each line of way. Strong plated cross-girders are
placed at 5 feet 3 inch centres, and on the top of these is laid a
flooring of old Barlow rails, terminating at the sides with sloping
wing-plates riveted to the cross-girders and main girders, the entire
surface being covered with an inch and a half layer of asphalte. Good
gravel ballast is placed on the top, on which are laid the sleepers
and rails. One central main girder of sufficient strength would have
been as efficient as the two central girders, but there was a
practical difficulty which prevented its adoption. The new girder-work
was built to replace an old structure of peculiar arrangement, and to
keep the traffic going on one line there was no alternative but to
make each line of way complete in itself.

[Illustration: Fig. 140, 144]

Fig. 143 illustrates an example of jack arches in concrete built
between strong plate-girders. The span of the girders was only 16
feet, but the opening or roadway was of considerable length, and
passed under a portion of a busy station yard. The girders are placed
at 6-foot centres, and tied together in pairs by 1¼-inch tie-rods,
three to the span, spaces of 6 inches in plan being allowed between
each set of the rods. The concrete was curved up to the top plate of
the girder, as shown, and the entire surface covered with a thick
layer of asphalte, on which were placed the ballast and permanent way.    141
Brickwork might have been used for the jack-arching, but concrete was
considered more convenient.

Fig. 144 shows the cross-section of a truss-girder bridge of 123 feet
span, carrying a double line of railway over a wide thoroughfare, the
load being placed on the lower flange. There are two main girders,
each 12 feet 6 inches deep in the centre, and 8 feet deep at the ends.
Plate cross-girders are placed at 4 feet 6 inch centres, on which is
riveted longitudinal plate-iron troughing, extending across the bridge
and terminating at the sides with wing-plates, as shown. The entire
floor is covered with a thick layer of asphalte previous to filling in
with ballast to receive the permanent way. Plate stiffeners are
adopted in this bridge very similar to those in Fig. 139.

Fig. 145 gives plan, elevation, and cross-section of a plate-girder
bridge of 95 feet span, carrying a double line of railway over a very
busy street. There are two curved-top main girders, each 10 feet 9
inches deep in the centre, and 6 feet 7½ inches deep at the ends. The
arrangement of cross-girders, longitudinal plate-iron troughing, and
permanent way, is very similar to that in the preceding example, but
the side wing-plates are carried up higher, and are riveted up to the
web-plate of main girder, forming continuous stiffeners from end to
end of the main girders. A light, ornamental, close cast-iron parapet
is bolted on to the top of the curved, or upper, boom of the main
girder, the top line of the parapet being carried out parallel to the
bottom boom of girder. This bridge crosses the street very obliquely,
and, although cast-iron columns were allowed at the edge of the
footpaths, the main spans are unavoidably large. When designing the
above bridge, the writer had to adopt a girder that would form a
screen, to provide a deck, or floor-way, which would be not only
water-tight, but also deaden as much as possible the sound or
vibration of passing trains, and at the same time give some ornamental
appearance to the girders and parapets. This bridge carries a constant
service of heavy trains; it is perfectly dry underneath, and is
remarkably free from noise or vibration.

[Illustration: Fig. 142]

Fig. 146 shows cross-section of a plate-girder bridge of 40 feet span,
carrying a double-line railway over a street, in a situation where the
depth from top of rails to under side of girders had to be made as
small as possible. Three main girders were used, the centre one being     143
double the strength of each of the outside girders. Instead of
ordinary cross-girders, transverse plate-iron troughing was adopted,
very similar in section to the longitudinal iron troughing in Fig.
145, but stronger. The troughing rested on the angle iron of bottom
flange of main girder, and was riveted to the vertical web-plates of
main girders, shallow additional vertical plates being inserted
alongside web-plates to prevent any drip-water or moisture coming in
contact with the main web-plates. The entire surface of the troughing
was well covered with asphalte before filling the hollows with gravel
ballast. An ordinary transverse wooden sleeper was placed in each
hollow, and on these sleepers the rails were secured as shown. In this
case--as in others of transverse troughing--the rain-water had to be
conveyed away from the hollow of each trough by a separate outlet into
longitudinal gutters shown at A, B, and continued on to the
abutments.

Transverse troughing is always more troublesome than longitudinal
troughing, as both ends of each trough must be effectually closed to
prevent the drainage water leaking out on to the web-plates, or angles
of the main girders. With longitudinal troughing the water is readily
carried away from each hollow, to cross drains constructed at the
piers, or abutments.

Fig. 147 shows cross-section of a truss-girder bridge, 120 feet span,
carrying a single line of railway over a river. The cross-girders are
placed at 10-foot centres to correspond to the vertical members of the
main truss-girder. Longitudinal plate-iron rail-girders are riveted in
between the cross-girders, and the entire floor is covered with curved
wrought-iron ballast plates, as shown. The rails are carried on
longitudinal timbers, which are bolted on to the rail-girders. Angle
iron brackets, riveted on the top of the cross-girders, keep the rail
timbers in position and gauge.

[Illustration: Fig. 145]

In each of the above examples, where longitudinal rail timbers are
adopted, flange rails are shown, as many engineers prefer to have a
continuous bearing for the rails on bridges, in case of rail fracture.
There is nothing, however, to prevent the chair road being laid on
longitudinal timbers, and for this purpose the writer has used chairs
of the ordinary pattern, specially cast with side lugs to grip the
timber, as shown in Fig. 148. Chairs of this form have a very firm        145
hold on the longitudinal timber, and the side lugs check any tendency
of the splitting or opening of the wood when putting in the spikes or
screw bolts.

Fig. 149 shows cross-section of a plate-girder over-line bridge, 32
feet span, carrying a private road, 12 feet wide, over a double-line
railway. The road traffic being small, the floorway was constructed of
creosoted planking carried on rolled I-iron cross-girders placed at 3
feet 8 inch centres, and riveted to the main girders. The horse-tread
track was provided with a second layer of planking, laid transversely,
to take up the wear, cross battens, 4 inches by 2 inches, being placed
at 12-inch centres, and sand spread between to give good foothold. A
light lattice-work parapet was bolted on to the top of the main
girders.

Fig. 150 gives cross-section of a plate-girder over-line bridge, 30
feet span, carrying a private road, 20 feet wide, over a double-line
railway. The main girders are tied together by lattice-work bracing,
spaced at 7-foot centres. Curved wrought-iron plates are laid across
from girder to girder, and butt against a narrow horizontal plate,
which forms part of the upper boom. The curved plates are riveted on
to the top of girder, and form a continuous iron floor, or deck, from
side to side of the bridge. Upon this iron floor is laid an ordinary
asphalte roadway. The outside girders are made deeper, and carry an
ornamental cast-iron parapet. In some bridges of a similar
construction, the roadway is formed of creosoted wooden block paving,
on a foundation of asphalte.

[Illustration: BRIDGE CARRYING THE D. W. AND W. RAILWAY (LOOP LINE)
OVER AMIENS STREET, DUBLIN. [_To face p. 144._]

[Illustration: Fig. 146, 147, 158, 159, 148]

Fig. 151 shows cross-section of a plate-girder over-line bridge, 28
feet span, carrying a public road, 35 feet wide, over a double-line
railway. The main girders, 2 feet 4 inches deep, are placed at 5 feet
2 inch centres, and are tied together by plate-iron cross-bracing 2
feet deep. Jack-arches of brickwork, 9 inches thick, are built in
between the main girders, the haunching being filled in with concrete.
The entire surface is covered over and made watertight with asphalte,
on which is laid the metalling of the roadway. The outside girders are
made considerably deeper, and have strong cast-iron-plate parapets
bolted on to the top booms. There is no doubt that jack-arching of
brickwork or concrete makes a very strong and permanent floorway, but
its dead weight is very great, and its adoption is not to be recommended  147
where iron or steel plate troughing can be obtained at a moderate
price.

Fig. 152 gives cross-section of plate-girder over-line bridge, 41 feet
6 inch span, carrying a public road, 25 feet wide, over three lines of
way. Two main girders are used, of sufficient depth to form parapets
or screens for the finished roadway. Plate cross-girders, placed at 6
feet 6 inch centres, are riveted to the web-plate and lower angle
irons of main girders; and on these is placed a flooring of plate-iron
longitudinal troughing to carry the metalled roadway.

Fig. 153 gives the particulars of a plate-girder over-line bridge,
carrying an important public road, 35 feet wide, over several main
lines and sidings. The carriage-way is carried by two girders placed
at 25-foot centres, and on the lower boom of these are riveted
lattice-work cross-girders to receive the plate-iron longitudinal
troughing and roadway. The footpath girders are set at a higher level,
and the load placed on the lower flange. The curved side brackets
merely act as bracing between the carriage-way girders and footpath
girders. A cast-iron-plate parapet is bolted on to the top of each of
the footpath girders, making a close screen, 6 feet high, above the
footpath. Lattice-work cross-girders were adopted for the convenience
of supporting small water mains and gas mains below the road-level.
The roadway is formed of ordinary metalling, and the footpaths of
asphalte pavement; the kerbing is of granite, and the side
water-tables of crushed granite concrete.

[Illustration: Fig. 149, 150, 151, 152]

Fig. 154 is a cross-section of a small uncovered lattice-girder
footbridge 41 feet span, and 5 feet wide, suitable for small roadside
stations. The top and bottom flange consist each of two angle irons,
those in the bottom flange being placed table side upwards, so as to
bring the entire section of both angle irons fairly into play, and
also to provide a better bearing for the channel-iron cross-girders
which carry the planking of the footway. When planking is carried on
the inside of light angle iron, as in Fig. 155, a severe strain is
produced at the point A; this is entirely obviated by placing the
bottom angle irons table side upwards, as in Fig. 156. Three of the
channel-iron cross-girders are extended outwards, and to the ends of
these are riveted tee-iron stiffeners to steady the main girders. In
some cases stamped, or ribbed, wrought-iron plates are used for a
footway, but, although more durable, they do not give such a secure or    149
agreeable foothold as timber. The ascent or descent of the bridge may
consist either of steps and landings, or of ramps, according to
circumstances or expediency. Sometimes these bridges are made with
curved tops, terminating in steps when nearing the steps, or ramps. It
is very questionable whether such an arrangement is a good one or a
safe one. There is always a feeling of insecurity when walking over a
sloping surface broken up by steps, and experience points out that it
is better to continue the footway level right across to the place
where the passenger must change his direction to go down the stairs or
ramp.

Fig. 157 gives cross-section of a covered lattice-girder footbridge,
62 feet 6 inches span, and 10 feet wide, suitable for an important
station. The upper boom of girder consists of two angle irons and top
plate, and the bottom boom of two channel irons. The cross-girders are
rolled joist-irons resting on the top tables of the channel irons.
Four of the cross-girders are extended outwards, and carry plate-iron
outside vertical brackets to stiffen the main girders. Three-inch
longitudinal planking is laid down from end to end of the bridge, and
on this is laid 1¼-inch transverse flooring, in narrow widths, to form
the walking deck. The footbridge is lighted from the sides by
continuous glazed sashes fixed in strong wooden framework, as shown.
The roof is covered with canvas bedded in white lead, and painted in
the same way as an ordinary carriage roof.

The above examples of under-line and over-line bridges are given more
with a view of illustrating some of the many different descriptions of
flooring, rather than to point out or suggest the type of main girder
to carry the load. The description and size of the main girders can be
varied to suit the span of the bridge, the requirements of the
traffic, and the opinion of the designer. For spans up to 50 feet it
will generally be found that web-plate girders are both simpler and
cheaper than lattice or truss girders; at the same time, there are
occasions where plate girders can be advantageously adopted for very
much larger spans, as, for instance, in the example given in Fig. 145,
where the deep plate girders form a most efficient screen.

[Illustration: Fig. 153]

Figs. 160 to 194 give diagram sketches of a few out of the many forms
of open, or truss, girders which have been adopted for large spans.
There are many types from which to make a selection, each one
possessing its own special features and advocates. In working out the     151
details of any, or all of them, there are some points which should
always be kept in mind when deciding the distribution of material in
the main booms. Rain-water, or moisture of any kind, is the great
enemy of wrought-iron or steel work, and therefore the plates, angles,
tees, or channel sections, should be so arranged as to afford the
least possible facility for the collection or lodgment of water. With
open, level booms, as in Figs. 137, 139, 140, 144, and 145, the
rain-water cannot collect, but runs off at the sides, and the plates
are quickly dried by the sun and wind. With trough booms, as in Fig.
158, the collected rain-water can only get away through holes drilled
for the purpose in the bottom plates. These holes are liable to become
choked up, but even when open they rarely carry off all the
accumulated water; some of it remains to corrode the plates, and is
only dried up by evaporation. The inside of trough booms should be
constantly inspected, and the exposed plates more frequently painted
than the rest of the girder. In a similar manner, in small double-web
lattice girders, with the lattice-bars inserted between two angle
irons, as in Fig. 159, the rain-water finds its way into the spaces at
A, A, in spite of the most careful packing or filling with cement
or asphalte. Numbers of small girders of this latter type have had to
be taken out after a comparative short life, in consequence of the
great corrosion and wearing away of the lower ends of the lattice-bars
and angle irons into which they were inserted.

It is most essential, also, that all portions of the girder-work
should be conveniently accessible for inspection and painting.
Complicated connections, and parts which are difficult to examine, are
liable to be overlooked, or, at the best, only painted in a very
imperfect manner. Neglected corners soon create deterioration, the
paint scales off, corrosion commences, and the working section is
gradually reduced. A discovered weakness in some of the important
parts points to an early condemnation of the entire structure. The
difficulty of access to the interior of box or tubular girders,
especially those of small or moderate dimensions, is a great objection
to that type of girder. Experience has pointed out that open girders,
free and exposed to the light and air, can be so much more effectually
inspected and painted.

[Illustration: Fig. 154, 155, 156, 157]

[Illustration: Fig. 160, 161, 162, 163, 164, 165, 166, 167, 168]

[Illustration: Fig. 169, 170, 171, 172, 173, 174, 175, 176]

[Illustration: Fig. 177, 178, 179, 180, 181, 182, 183]

[Illustration: Fig. 184, 185, 186, 187, 188, 189, 190, 191]

[Illustration: Fig. 192, 193, 194]

Perhaps one of the most anxious tasks which falls to the lot of an
engineer is the renewal of under-line bridges and viaducts on a
working line. On a new line in course of construction the entire site     158
of the work is at the disposal of the erectors, and the building of a
bridge or viaduct can be carried on with a freedom which cannot be
obtained on an open line. On a working railway, the train service must
be kept going, irrespective of renewals, and very often the best that
can be done is to reduce the double line to single line working at the
site of the operations. It is not always expedient or possible to make
a temporary bridge and diverted line for traffic purposes, as the
expenditure to be incurred might be too great to warrant the outlay,
or there may be local difficulties to effectually prevent the
introduction of a provisional structure. The taking down of one half
of the old structure may necessitate the removal of stays and bracing
affecting the stability of the half remaining to carry the traffic,
and thus render temporary shoring and bracing necessary. The erection
of the new work in such a limited space has to be watched with great
care; all cranes, lifting appliances, and scaffolding must be kept
clear of vehicles moving over the running-line, and very frequently it
is found prudent to cease erecting operations during the passage of a
train.

In very many cases of renewals, the description and arrangement of the
old structure will materially influence or control the design for the
new one, and the details of the latter must be schemed out so as to
disturb as little as possible the stability of the old work remaining
as the working road.

The following list gives the lengths of the main spans of some railway
bridges, and may be found useful for reference:--

  LENGTHS OF MAIN SPANS OF SOME LARGE RAILWAY BRIDGES.

  -----------------------------------+-------+----------------
           Name.                     | Span. |  Description.
  -----------------------------------+-------+----------------
                                     | feet. |
  Forth Bridge                       | 1,710 | Cantilever.
  Niagara                            |   821 | Suspension.
  Sukkur                             |   820 | Cantilever.
  Poughkeepsie, U.S.A.               |   548 | Cantilever.
  Douro                              |   525 | Arch.
  St. Louis                          |   520 | Arch.
  Cincinnati                         |   515 | Linville truss.
  Haarlem                            |   510 | Arch.
  Kuilemburg                         |   492 | Lattice bow.
  St. John’s River                   |   477 | Cantilever.
  Niagara                            |   470 | Cantilever.
  Britannia                          |   460 | Tube.159
  Ohio River,  Pennsylvania          |   442 | Pratt through truss.       159
  Saltash                            |   434 | Tube and girder.
  Hawkesberry Viaduct                |   410 | Compound truss.
  Conway                             |   400 | Tube.
  Vistula                            |   397 | Lattice.
  Spey River, Garmouth, N.B.         |   350 | Bowstring.
  St. Laurence                       |   330 | Tube.
  Hamburg                            |   316 | Double bow.
  Cologne                            |   313 | Lattice.
  Runcorn                            |   305 | Lattice.
  Sunderland                         |   300 | Bowstring.
  Rondout Bridge, Buffalo            |   264 | Pratt through truss.
  Newark Dyke (New)                  |   259 | Lattice bow.
  Tay Bridge (New)                   |   245 | Lattice bow.
  Ohio River, Louisville             |   245 | Fink truss.
  Beaver Bridge, Pennsylvania        |   230 | Pratt deck truss.
  Craigellachie Bridge               |   200 | Lattice.
  Rohrbach Bridge, St. Gothard River |   197 | Wrought-iron arch.
  Windsor Bridge                     |   187 | Bowstring.
  Victoria Bridge over Thames        |   175 | Wrought-iron arch.
  Shannon River Bridge               |   165 | Bowstring.
  Carron Bridge over Spey            |   150 | Cast-iron arch.
  Preston Viaduct                    |   102 | Cast-iron arch.
  Trent River Bridge                 |   100 | Cast-iron arch.
  -----------------------------------+-------+----------------------


Retaining Walls.--Instances frequently occur during the construction
of a railway where it is advisable, if not absolutely necessary, to
substitute retaining walls in preference to forming the slopes of
cuttings and embankments.

The excavation of a cutting may be greatly reduced in quantity by
introducing low retaining walls, as in Fig. 195, and the saving in the
material to be removed will be all the more important in those cases
where cutting is in excess of embankment.

The amount of filling for an embankment and the land on which it has
to be formed may both be considerably diminished by building a low
retaining wall, say 6 or 7 feet high, at the foot of the slope, as
shown in Fig. 196. Such a retaining wall makes a most efficient fence
and well defined boundary of property.

[Illustration: Fig. 195, 196, 197, 198, 199, 200, 201]

The policy of adopting low retaining walls in cases like the above        161
will depend mainly upon the cost of building materials as compared
with the cost of earthwork and land.

Where land is very valuable, and where residential property, streets,
or roads must be interfered with as little as possible, the retaining
walls may have to be carried up to the level of the original surface
of the ground, as in Fig. 197, which is shown as for a cutting 25 feet
deep. The walls may be built of masonry, brickwork, or concrete, or a
combination of them, and the dimensions or thickness will depend upon
the description of material to be supported. Weeping holes, or small
pipe drains, should be formed in the walls, a little above formation
level, to take away any water which may collect at the back.

Where the cutting is through soft, wet, treacherous clay, liable to
slip or expand, it may be necessary to insert arched thrust girders
extending from side to side, as in Fig. 198, so that the outward
pressure against the one wall may counteract against the outward
pressure of the other. The thrust girders should be placed at from 10
to 15 feet centres, and be well braced together in plan to enable them
the better to resist any tendency of bulging out of the walls.

A similar arrangement of high retaining wall may be introduced in
embankment to lessen the encroachment on streets or public roads, as
shown in Fig. 199.

In making a railway through thickly populated towns, it is generally
preferable to construct the line on arches rather than on earthwork
filling between two high retaining walls. The numerous openings are
available for future streets, or means of communication from one side
to the other, and the arches themselves can be profitably utilized for
stables, stores, offices, and workshops.

Fig. 200 shows a narrow rocky pass with deep rapid river on the one
hand and high cliffs on the other, the only available ledge being
already occupied by a public highway. By building a retaining wall, as
indicated on the sketch, and excavating a little out of the cliff,
space may be obtained for a line of railway; or the arrangement may
have to be reversed, and the retaining wall for the railway built
along the margin of the river, as in Fig. 201.

In both the cases, Figs. 200 and 201, not only must there be a number
of weeping holes left in the lower part of the wall, but there must be
sufficient well-built drains and culverts under the filling and through   162
the wall to carry away all ordinary or flood water coming down from
the cliffs and hills above. Where a retaining wall is built along the
margin of a river, the lower portion, which will be in contact with
the water when the river is full, should be constructed of selected
large heavy stones to withstand the scouring action of the water, and
any brushwood or floating timber which may be brought down by flood
water.

Where retaining walls are built to support wet clay, or in embanked
places on wet side-lying ground, the efficiency of the work will be
much increased by constructing a layer, two or three feet in
thickness, of dry, flat, bedded stones carefully hand-laid, from the
foundation to the top of the wall, as shown in Fig. 199.

These dry stones form a continuous vertical drain to take away water
from any part of the earthwork down to the outlets left in the lower
portion of the wall.

The building of retaining walls entirely of dry stone is very
questionable economy, and entails a constant expenditure in
maintenance and renewal. The working out of one stone loosens the
surrounding portion of the wall, and if not at once repaired, a length
of the wall will fall down, bringing with it a large quantity of the
earthwork.

If readily obtained, large heavy stones should be selected for the
coping of retaining walls, so as to minimize as much as possible the
chance of their disturbance or displacement. Where lighter stones have
to be used, or bricks laid on edge, they should be bedded and pointed
in cement.

In many places it is necessary to form wide and massive foundations of
concrete on which to build the retaining wall; and in some cases of
soft, treacherous ground, timber piling may be necessary.


Tunnels.--It would be difficult to assign a date to the first
examples of subterranean works constructed for utilitarian purposes.
Nature had furnished so many grand specimens of caves, grottoes, and
underground passages formed in the solid rock, that man soon grasped
the principle, and essayed to carry out similar works on his own
account. The early attempts would probably be limited to forming
places of shelter, storage or security. Advantage would be taken of
those rocks which from their locality, accessibility, and compactness
of material, promised favourable results. The appliances being few and
primitive, the work of construction would be laborious and slow. So       163
long, however, as the workers restricted their operations to the solid
rock, they had merely to contend against the hardness of the material,
as the opening or passage-way, once made, required no further support
or attention; but as the wave of progress swept onward, man was
compelled to deviate from the lines originally followed by nature, and
had to form his subterranean pathway through softer material, where
the workings required substantial support. The search for minerals of
various kinds led to the driving of long headings or galleries
underground, and as these had frequently to penetrate through strata
of a soft and yielding character, strong timber framework had to be
introduced to afford stability to the works, and safety to the
workers. For ordinary mining operations, strong rough timber supports
may meet all requirements, and may last until the heading is worked
out and abandoned; but for subterranean passages or tunnels which are
intended to form permanent means of communication, the strongest and
most durable materials must be used to protect the interior as far as
possible from deterioration or decay. Heavy timbering might be
sufficient for mere temporary purposes, but substantial masonry or
brickwork side walls and arching became necessary for permanent work
in those portions where the tunnel required artificial support.

The first tunnels of any importance were most probably those
constructed for canal purposes. Many of them were of considerable
magnitude, and in some instances were from two to three miles in
length. They were substantially lined with masonry or brickwork at all
places where the tunnel passed through soft material or loose rock,
and from the solid nature of the work, and the many years they have
been in existence, they thoroughly testify to the ability of the
constructors.

The introduction of railways involved the making of a large number of
tunnels, perhaps more so in the beginning, when it was thought that
the use of the locomotive would be confined to very moderate
gradients, and when engineers hesitated to adopt the steeper inclines
and sharper curves which form the practice of modern times. Another
element of consideration also consisted in the fact that the first
railways were designed to connect the most populous and busiest
districts, where the prospects of heavy traffic would appear to
warrant a large outlay for works of construction. As the system spread
and railways extended further away from the important centres, the        164
probabilities of traffic would become less promising, and efforts
would be made to keep down cost of construction, and avoid tunnel work
as much as possible.

It is not easy to define where cutting should end and tunnelling
begin. There is no practical difficulty in making a cutting 50, 60, or
70 feet deep, with slopes to suit the material excavated, and the
estimated cost per yard forward may even compare favourably with the
cost of average tunnel-work. But there are other questions which must
be kept in view--the time required to form the cutting, the space to
be obtained on which to deposit the enormous quantity of excavated
material, and the probable difficulty in obtaining the large area of
land necessary for the cutting.

Before deciding the actual position of a tunnel, both as to line and
level, it is necessary to obtain the most reliable information
possible regarding the strata through which it has to pass. In
addition to the geological indications on the surface and in the
locality, borings should be made, and trial holes or shafts sunk along
the proposed centre line of the work, and from these an approximately
accurate longitudinal section can be laid down on paper, showing the
respective layers of material to be cut through, and the angle at
which they lie. With these particulars before him, the engineer may,
in some cases, consider it more prudent to change the position of the
tunnel in preference to incurring specially difficult or tedious work
in dealing with some recognized unfavourable material. Occasionally
the route may be slightly varied and better material obtained, but
very frequently there is little to be gained except by a wide
deviation from the original line.

Solid rock, except for the slow progress, is perhaps the most
favourable material for tunnelling, as the timbering, side walling,
and arching can be almost, if not entirely, dispensed with.

Loose rock, although more readily removed, necessitates strong
timbering to prevent large masses breaking away and falling into the
tunnel.

Some clays are very compact and tenacious, and will stand well with
moderate timbering, but even these should not be left long before
following up with the side walls and arching.

Many clays give much trouble by expanding, or swelling out, when the
excavation penetrates the layer, and although extra strong timbering      165
may be used, and be placed closer together, the logs and planks are
frequently bulged out and broken by the action of the clay. Specially
strong supports are required for this description of clay, and extra
thickness of material in the permanent work of side walls and arching.

Solid unbroken beds of chalk are not difficult to cut through: the
material is easy to work, and the excavation will stand with ordinary
timbering; but where the chalk is broken and intersected with deep
pockets of gravel and sand, the operations are very much impeded. The
loose material, once set free by cutting through the confining barrier
of chalk, will quickly fall into and fill up the excavation if not
held back by strong timbering. Side walls and arching are generally
necessary for tunnels through chalk.

Soft wet clay, quicksands, or other strata having springs of water
percolating through them, are serious obstacles in the way of
expeditious tunnelling. No sooner is one cube yard of this soft
material removed than another slides down, or is washed down, to take
its place. When once the excavation taps the water-bearing strata,
large volumes of water will find their way into the workings, and must
be conveyed away to the mouth of the tunnel, or pumped up through the
nearest shaft. The timbering of the sides and roof through this
description of working is very tedious, and attended also with a
considerable amount of risk. The absence of really solid ground on
which to place or shore up the supports, taxes the skill of the
excavators, and very often, when a short length has been made
apparently secure, it will come down with a run, compelling all hands
to beat a hasty retreat. The permanent lining through such treacherous
material should follow the excavation very closely, and special care
should be exercised in building the walls, arching and invert.

In the excavation through stratified rocks it is necessary to note
carefully the lie of the strata, whether horizontal, vertical, or
shelving, as with each one the excavators are exposed to risks,
against which every precaution should be taken. A large horizontal
slab of solid-looking rock will suddenly break and fall down without
any warning. A heavy mass from a vertical layer, perhaps unkeyed, or
loosened, by an adjacent blasting operation, drops down when least
expected; and pieces from the high side of the shelving layers detach
themselves and slide into the working in a most unaccountable manner.

No attempt should be made to carry a tunnel through material which has    166
been disturbed or at all affected by any natural slip or cleavage, as
although the strata may be hard and compact in themselves, they have
really no solid or fixed foundation. The sliding away, once initiated,
is certain to continue, and, accelerated by the tunnelling operations,
will most likely, sooner or later, crush in the tunnel and sweep away
every vestige of the work. Amongst the great mountain ranges these
natural disturbances are by no means rare, and it will be wiser to
keep away from their locality, even at the expense of a longer tunnel.
Unfortunately, instances are on record of tunnels made, or in course
of construction, through hillsides which had already commenced to
slide away from the more solid rock, and the ultimate results were a
further sliding away and total destruction of the work.

The lower slopes and outlying portions of high mountains are the most
exposed to these natural slips, and they should be most carefully
studied before commencing any tunnelling operations through them.

To facilitate drainage, it is essential that a railway tunnel should
be laid down with a gradient or gradients falling in the direction of
one or both ends of the tunnel. In nearly all tunnels a considerable
amount of water finds its way in through the weeping-holes left for
that purpose in the side walls, and must be carried away in suitable
drains. If the quantity of water be small, ordinary water-tables, one
on each side, may be sufficient; but for large volumes of water it
will be necessary to build substantial side-drains, or an ample
culvert below the level of the rails.

The gradients in a tunnel should be moderate, and not by any means
excessive, or likely to tax the hauling powers of the locomotives.
When an engine is working nearly to the utmost of its power on a steep
tunnel incline, and the speed has become very slow, the exhaust
vapours or gases from the funnel strike the arching with great force,
and are deflected down on to the footplate in such dense volumes as to
almost suffocate the driver and fireman. The writer will never forget
two or three trying experiences in foreign tunnels, when he and the
engine-staff were compelled to leave the footplate and climb forward
to the front of the funnel, leaving the engine to work its way alone.
Except for very short tunnels it is wiser to have easy inclines, and
to restrict the steep gradients to the open line, where the very slow     167
travelling, or even the coming to a stand from “slipping,” may not
produce unpleasant or alarming consequences.

In tunnels of any length it is usual, where possible, to construct
shafts extending from the surface of the ground overhead down to the
tunnel below. These shafts serve the double purpose of enabling the
excavation to be carried on at an increased number of faces, and act
as permanent ventilators after completion. In some cases the shafts
are sunk exactly over the centre line of the tunnel, in others a few
yards away from the centre line. The latter arrangement, if not quite
so convenient for hoisting material while carrying on the excavations,
has certainly the great after advantage that anything falling or
maliciously thrown down the shaft cannot strike a passing train. The
short side-gallery, or space between the tunnel and the shaft,
provides a good refuge for workmen employed in repairs, and a
convenient site for storing a few materials advisable to keep on hand.

Occasionally favourable opportunities present themselves for making
horizontal shafts. For a portion of its length the tunnel may be
located at no very great distance from the precipitous sides of some
deep mountain ravine, or run near to the cliffs on the sea-coast, and
advantage can be taken to drive a lateral heading or gallery through
which the material from the tunnel excavation may be conveyed and
thrown out into the gorge or seashore below.

In many cases the surface of the ground rises so abruptly from the
faces of the tunnel and ascends to so great a height, that shafts of
any kind are entirely out of the question, and the whole of the work
must be carried on from the two ends. The rate of progress is
consequently much slower, and the ventilation more difficult. In a
shaftless tunnel of considerable length, and with a frequent train
service, the question of providing suitable appliances for promoting
artificial ventilation is of the utmost importance.

When the centre line of the tunnel has been accurately set out on the
ground, and the levels of the different parts of the work decided, the
construction of the shafts and the driving of the headings can be
commenced. Working shafts intended to serve for permanent ventilation
are generally made nine or ten feet or more in diameter, and are
usually lined with substantial brickwork or masonry. When the well-like   168
excavation has been carried down a few yards, or as far as it can be
taken without the risk of the earth falling in upon the sinkers, a
strong curb of hard wood or iron of the same diameter as the finished
shaft is laid down perfectly level and to exact position, and on this
curb the ring or lining of brickwork or masonry is built up to the
level of the ground. The first length finished, the excavation
downwards is resumed, and the interior lining continued, either by
allowing the first length to slide down as the material below is
gradually removed, and building further lining on the top, or by
excavating and propping up the curbing with strong timbers below. When
working to the latter method, stout wooden props of convenient length,
stepped on to sole-pieces, are adjusted to the under side of the
wooden curb above, the material is then removed for the thickness of
the brickwork or masonry, and another curb accurately set to level and
position; on this is built a length of lining up to the first curb.

This work of under-building or under-pinning must be carried out with
great care and in segments; no props must be removed until the curb
immediately above is well supported by the new lining, and the inside
of the lining must be watched and tested to prevent any tilting. All
spaces at the back of the work must be filled in and well packed with
hard dry material. As the shaft is continued downwards the mode of
working may have to be varied; different descriptions of material may
be encountered, and blasting, shoring, and pumping may each in turn be
necessary.

When down to the full depth, the lower length of the shaft will have
to be securely supported by strong timbers, until it can be properly
built into and incorporated with the arching of the tunnel or side
gallery.

The completion of the shaft enables the workings to be commenced on
each side, the excavated material can be hoisted to the surface, and
building material lowered down. When the tunnel works are finally
finished, the lining of the shaft should be carried up until it is 15
or 20 feet above the level of the surface of the ground, and a
dome-shaped iron grating placed on the top as a protection against
stones or other articles which malicious persons might attempt to
throw down the shaft.

Some shafts are only intended for the temporary purpose of lifting the
excavations from below, or lowering building materials down, and when     169
the work is completed they are filled in again and closed. These
service shafts are generally made square in section, and are merely
lined with wood. Strong vertical timbers are placed at the four
corners, to which horizontal double cross-pieces are bolted, thick
planking being placed vertically at the back of these cross-pieces to
support the sides of the excavation.

The _heading_ of a tunnel is a narrow passage or gallery cut
through from end to end of the works in the direction of the centre
line. Where there are shafts, the cutting of the heading can be pushed
on from several points, and be completed much more rapidly than when
the working is restricted to the two ends. Headings are usually made
just sufficiently large for the miners to work, say about 5 feet 6
inches high by about 3 feet wide, the object being rather to expedite
the driving of the driftway than to remove large masses of material.
They must be set out with great accuracy, and be constantly checked as
the driving is in progress. When completed from end to end, the centre
line can be checked throughout, and the course actually taken compared
with the course intended. If there has been much variation in the
narrow pioneer pathway, either in line or level, the amount of the
divergence must be rectified when ranging the final centre line for
the full-size excavation.

Tunnels cannot always be delayed until the heading is cut through for
the entire length. In many cases the heading, the full-size
excavation, and the permanent lining have all to be carried on at the
same time, but as the work of the heading is smaller in extent, that
portion of the operations can usually be kept well in advance of the
others. The critical moment arrives when the headings from opposite
directions meet, as any deviation or want of coincidence must be
adjusted in the portion of the tunnel still remaining to be opened out
to full size. Some tunnels of moderate length have been constructed
without any heading at all, the excavation being taken out to the full
dimensions from the commencement.

The heading of a tunnel assists not only in the correct alignment of
the work, but furnishes at the same time an accurate knowledge of the
strata passed through. It is also of service for ventilation,
communication, and drainage.

In some cases the heading is driven at the bottom of the tunnel
section, as in Fig. 211, and in others at the top, as in Figs. 202 and    170
204. Many of the earlier tunnels were constructed on the former
system, while of late years the latter method has been very largely
adopted. The bottom heading may perhaps in some instances be more
efficacious for drainage, but it is very liable to be frequently
choked up when taking out the excavation to the full size, and the
lower surface is much cut up by the movement and conveyance of
materials. Another disadvantage arises from the necessity of removing
such a large amount of the cutting approaching the tunnel entrance
before a beginning can be made to the bottom heading. The top heading
has the advantage that it requires less removal of open cutting
previous to its commencement, and, being high up in position, there is
less chance of its being stopped up by falling material, the finished
excavations being carried out on the sides and below the heading.

Where the headings are cut through solid rock, stiff shale, or compact
chalk, little or no supports are necessary, but where they pass
through clay or loose material, timbering will be required for sides,
roof, and floor. Rough round poles, about 6 inches in diameter, are
generally used for verticals, and are firmly secured to transverse
sole-pieces, and on the top of these verticals strong transverse
top-sills are fastened by means of rough tenons or checks. Strong
boards are inserted at the back of this framework to keep the earth
from falling into the working. The distance apart of the verticals
will depend upon the description of material excavated; in very soft
places they will have to be placed very close together, but where
fairly sound and tenacious they may be placed at about 3-foot centres.
The excavated material must be conveyed away to the entrance of the
heading in small hand-trucks running on planks or light rails.

The widening out of the excavation to the full size will be a
repetition on a large scale of the work carried out in the heading,
with the difference that, the exposed surfaces being of so much
greater extent, extra care and precautions must be taken with the
framework and shoring of the timbering.

[Illustration: Fig. 202, 203]

The form and arrangement of the timbering, as well as the number,
sizes, and positions of the pieces, must be determined by the material
of the excavation and the contour line of the finished arching or
lining. The framework, which would be sufficient to support ordinary
soft material, must be largely augmented both in quantity and scantling   172
to meet the requirements for wet treacherous clay.

Figs. 202 and 203 give end view and longitudinal section of timber
framework frequently adopted for average tunnel work. The positions of
the different pieces will explain themselves and the duty they have to
perform. The main struts, or raking pieces, which have to sustain
great pressure, may be shored against the finished lengths of masonry
or brickwork. The timbering of the sides can be removed as the lining
proceeds, but in many cases the round logs and boards near the crown
cannot be withdrawn, and have to be left in the work, the space
between the top of the arching and under side of the boards being
firmly packed with brickwork, masonry, or dry rubble stonework.

As the tunnel lining is generally carried forward in short lengths,
following up the main excavations, the centering for the arching
should be of such description that it can be readily transferred or
moved forward as the work proceeds. The form of the centering, and the
spacing of its upright supports, must admit of sufficient width for
one or more lines of rails for the waggons required to remove the
excavated _débris_ and convey the building materials used in the
lining.

Picks, bars, and shovels are the tools used in the excavation of the
softer material and loose disintegrated rock, but for the hard rock,
blasting will be necessary. The tunnel opening being comparatively
small, only moderate blasting charges can be used with safety, and
these must be placed so as to break up the rock-bed in a suitable
manner for working, and without shaking or damaging the already
completed excavation. Ordinary hand-drills, or _jumpers_, may be used
for forming the charge holes, a number of them being at work at the
same time, and the charges fired very closely one after the other. As
the blasting operations necessitate the retiring of the miners to a
considerable distance, out of the way of flying fragments, and the
remaining away until the foul air has been dispelled, it is advisable
to fire off several charges about the same time, and thus minimize as
much as possible the stoppage to the drilling and clearing away the
loosened material.

[Illustration: Fig. 204, 205, 206, 207, 208, 209, 210, 211]

Mechanical drills, worked by compressed air or other motive-power, are
now very extensively used where the rock is solid and continuous. They
are much more expeditious than the hand drills, but they are costly in    174
their installation, and also in their working and maintenance.

In some tunnels, where the material has been firm and dry, the upper
portion of the excavation has been first removed, and the masonry and
brickwork lining built in position down to about the springing of the
arch, the remainder of the excavation being afterwards taken out, and
the side walls built by means of shoring and underpinning.

In other tunnels the complete section has been excavated and timbered,
and the work of building commenced from the foundation of the side
walls. A strong continuous invert from side wall to side wall is
necessary where passing through soft swelling clay or loose strata
intersected with small streams of water. Where the material is very
solid and dry, it is not necessary to introduce inverts, but the
foundations of the side walls should be laid at such a depth below
rail-level as not to be affected by drain-water running through the
tunnel.

The side walls and arching may be either of masonry or brickwork, but
should be of the best description, especially for the facework. For
brick arching only the best hard-burnt bricks should be used, and the
inner or exposed ring should consist of selected hard fire-bricks to
withstand the heat and gases escaping from the funnels of the
locomotives. The thickness of the side walls and arching will depend
upon the description of material to be supported. In some places a
comparative thin lining may be sufficient, while in others extra
thickness must be given to resist the great pressure exerted by
expanding clay and loose wet strata.

Weeping-holes, or small drain-pipes, placed low down must be left in
the side walls every three or four yards, or closer in very wet
places, to allow the water collected at the back of the walls to
escape into the side drains of tunnel. In building the arch portion
every effort should be made to have close solid work without any open
joints or spaces through which the water may run, and the crown of the
arch and a few feet down on each side should be coated with cement or
asphalte to lead all water away from the top to the sides. Water
dripping from the under side of the arch on to the line is a great
destructor of the permanent way materials, especially the fastenings;
and bolts, nuts, fish-plates, and spikes placed in a wet dripping
tunnel will not last half the time they would out in the open line,
where they would have the sun and wind to dry them.

[Illustration: Fig. 212, 213, 214, 215, 216, 217, 218, 219]

Small arched recesses or niches should be formed in the side walls at     176
convenient distances to serve as refuges for platelayers or others
working in the tunnels.

It is most essential that the space between the masonry and brickwork
lining and the facework of the excavation should be carefully filled
in and hard packed, so as to prevent the possibility of pieces of rock
or other material falling on to the top of the arch. The neglect of
this precaution may lead to a casualty years after the tunnel has been
completed.

It would be impossible to over-rate the importance of a constant
faithful supervision of the building of the lining, especially the
arching. The work has to be carried on by workmen in cramped
positions, with imperfect light, and surrounded by all kinds of
obstacles and inconveniences, and unless a detailed inspection be
rigidly maintained, a carelessness in the selection of the materials,
and a laxity in the workmanship, will be the inevitable result.

Figs. 204 to 219 are sections of tunnels which have been constructed
for double and single line railways. The sections give the normal form
and dimensions adopted in each case, although there may have been many
portions of the work where unfavourable or treacherous material
necessitated an increase in the thickness of the side walls, or of the
arching, or of both. The types vary in accordance with the opinions of
the designers as to the most suitable section for the purpose, and
range from the comparatively thin lining and vertical side walls shown
on Fig. 207, to the almost circular form and very thick lining shown
on Fig. 216. The latter is the section which experience has proved to
be the best to sustain the enormous all-round pressure exerted by
certain descriptions of swelling clay.

Careful judgment will be required to decide which parts of a rock
tunnel may be left unlined. The apparently solid-looking portions are
oftentimes deceptive, and numbers of instances are on record of large
pieces of rock falling down in tunnels which for many years had been
considered as thoroughly secure. Where there is any doubt it is better
and safer to put in a lining, even if only to the extent of an arching
springing from side walls of solid rock, as shown on Fig. 206. A
moderate additional expenditure at the time of construction may
prevent a serious catastrophe afterwards.

[Illustration: Fig. 220, 221, 222, 223]

The faces or entrances to tunnels may be constructed with curved wing     178
walls, as in Fig. 220, or with straight wing walls, as in Figs. 221,
222, and 223. Where the approach cutting is in rock, the latter form
is generally adopted.

It would be misleading to put down any average price for tunnel-work.
So much depends upon the locality, the description of material to be
excavated, the cost of masonry or brickwork, and the cost of labour.
Added to these come the unforeseen troubles of slips and water-laden
strata, creating difficulties which baffle the miners for a time, and
add enormously to the expenditure. Some tunnels for double line have
been constructed in good ground, and under favourable circumstances as
to building materials and labour, for as low as £32 per lineal yard;
while others, carried out under adverse conditions, have cost as much
as £150 per lineal yard. A medium somewhere between the two should
represent the cost of tunnel-work through ground which does not
present any special difficulty. At the same time it must be borne in
mind that simple tunnelling which can be done in one locality for £50
or £60 per lineal yard, would be increased 20, 30, or 40 per cent. in
another, where building material for the lining is scarce and
expensive.

Tunnel-work abroad will generally cost more than the same work at
home. The native labourers may perhaps be procured at low rates, but
the skilled workmen must be brought from a distance, and will obtain
high wages.

Another form of tunnel-work, generally termed the covered-way system,
is frequently adopted in towns and places where land and space are
very valuable. This method consists in the excavating and removing of
earthwork to admit of the building of the side walls and arching of a
suitable tunnel-way, and then filling in over the top to a depth of
three or four feet, or up to the level of the original surface of the
ground. This work may be carried out by either removing the entire
width of the earthwork before the commencement of any building
operations, or by first forming two deep, well-shored trenches, in
which to build the side walls up to about arch-springing. In bad
ground the latter arrangement has the advantage, as the shoring and
strutting to hold up the sliding material is limited to the widths of
the two narrow trenches, and the centre block of earthwork is left
untouched as a support to the strutting. When the side walls have been
built sufficiently high the upper portion of the centre block of
earthwork can be removed to allow of the erection of centering and        179
building of the arching, and afterwards the remaining portion of
earthwork can be removed at convenience. In this manner a tunnel-way
may be constructed under streets, gardens, and even under buildings.
Being nearly all done in the open, the work is more under control than
in an ordinary tunnel, but it is usually very costly. Temporary or
diverted roads must be arranged; the excavated material must generally
all be removed by carts, sometimes to long distances; and provision
must be made for diverting the network of sewers, gas, and water pipes
which are intercepted along the route.

Fig. 224 is a sketch of covered-way with brick arching. Fig. 225
illustrates another type where cast-iron girders and jack-arches of
brickwork were introduced on account of the small headway. In soft
yielding clay it is necessary to construct strong inverts, as
indicated in the sketches. Recesses for the platelayers should be
provided every ten or fifteen yards.

The above systems of covered-way were largely adopted in the
construction of the underground portions of the Metropolitan Railway
and District Railways in and around London.

[Illustration: Fig. 224, 225, 226]

In addition to the ordinary type of tunnel formed by first excavating
the material and then lining the opening with brickwork or masonry,
tunnels of moderate size have been constructed of cast-iron tubes,
similar in section to Fig. 226. The tubes were cast in short segments,
bolted together inside, the outer circumference, or surface in contact
with the earth or clay, being left free from projections of any kind.
By making the segments with bolt-holes exact to template, they were
readily fitted together in the work, and a thin layer of suitable
packing material placed between the bolting-flanges sufficed to render
the tubes water-tight. The tunnelling was carried on by means of a
short length of slightly larger tube, or cap, made of plate-iron or
steel, which fitted over the leading end of the main tube. The front
end of this cap was made very strong, and provided with doors through
which the miners could work. A series of hydraulic presses attached to
the cap were brought to bear on the bolting-flange of the last
completed ring, and as the excavated matter was removed by the miners
from the front the cap was forced forward by the hydraulic presses,
and another ring of cast-iron segments inserted. On the City and South
London Railway, constructed on the above system, the small annular
space formed round the cast-iron tube by the operation of the sliding     181
cap was filled in with cement grouting by means of an ingenious
machine designed for the purpose.

Large tunnels under rivers or tidal estuaries must each be dealt with
according to the particular circumstances of depth below stream-bed,
material to be cut through, length of tunnel, and gradient. The chief
obstacle to be contended against in so much of the river tunnel-work
is the large volume of water which pours into the workings through
fissures in rock or seams of gravel and sand, necessitating the
constant use of most powerful pumps. In ordinary land tunnels the
gradients are generally laid out to fall towards one or both
entrances, and any water finding its way into the excavations may be
led away to the entrances by drains or pipes. On the other hand, in a
river tunnel the gradients generally fall away from the entrances down
towards the centre of the river, and all water coming in must be
pumped out and raised up to at least the level of the river. In places
where the water comes streaming in from many points, any failure or
stoppage of the pumps would place the lives of the miners, and the
security of the work itself, in great jeopardy. Iron shields, or
protection chambers for the miners advancing the excavation, have been
used with great success in carrying on work through loose wet strata
which appeared to defy all other means of progress. Solid rock, chalk,
or compact clay, may present no difficulty so far as they go, but a
continued dip in the gradient, or a line of fault, may suddenly change
the entire course of operations, and require the immediate use of the
most powerful pumping machinery and protective appliances. The special
features of each case will demand special precautions, and the
judgment and inventive powers of the engineer will be severely tested
in coping with the difficulties with which he is surrounded.




  CHAPTER III.                                                            182

  Permanent way--Rails--Sleepers--Fastenings--and Permanent way laying.


Rails.--Accustomed as we now are to the substantial character of the
permanent way of our railways, we can scarcely realize that in the
earlier examples the rails or tram-plates were made of wood. The first
lines of which we find any record were those constructed to facilitate
the conveyance of coal, iron ore, stone, slate, or other heavy
materials to shipping ports or points of distribution. Speed was a
matter of little importance, the principal object being to introduce a
distinct surface or roadway which would allow a heavier load to be
hauled without increasing the hauling power. As a heavily loaded
wheelbarrow, difficult to move on an ordinary road, can be readily
wheeled along a wooden plank, so it may have been inferred that strong
timber, laid in parallel lines and level and even on the upper
surface, would form a track, or roadway, presenting far less
resistance than the ordinary gravelled or paved roads.

The wooden tramway was the first improvement over the ordinary road.
The idea once originated, various types were soon introduced, and the
sketch shown in Fig. 227 illustrates one which appears to have been
early suggested and largely adopted. Wooden cross-sleepers, A, A,
were placed at convenient spaces, and on the top of these strong
timber planks or beams, B, B, were spiked at proper distances to
suit the wheels of the waggons or four-wheel trucks, which had flat
tyres like ordinary carts. The spaces between the sleepers were filled
in with gravel or broken stone to form a roadway or hauling path for
the horses. A little later _double rails_ were introduced, by placing
a second or upper timber on the top of the lower one, as in Fig. 228.

[Illustration: Fig. 227, 228, 229, 230, 231, 232, 233, 234, 235]

This double rail arrangement not only strengthened the framework, but
by increasing the height allowed a greater quantity of suitable           184
material to be placed over the sleepers to protect them from wear by
the horses’ feet. It can be easily understood that a wooden tramway
could not be very durable. It would be affected by the sun, rain, and
snow, and particles of sand and gravel thrown on to the tram beams
from the hauling path would hasten the abrading or wearing away of the
soft portions of the timber into hollows, leaving the hard knots
standing out as projections. The uneven surface would produce a series
of blows every time a loaded truck passed along, loosening the pieces
and rendering the repairs constant and expensive. To obviate the rapid
wear of the tram-timbers continuous narrow bars of wrought-iron were
fastened on to the running-surfaces; these in a measure prolonged the
life of the timbers, but at the same time added to the number of the
pieces and fastenings to be maintained.

Primitive as this description of road appears to be, it was in use for
many years in some parts of the United States of America, and even
after the introduction of the early locomotives; timber was abundant
and cheap, and iron in any form was costly. These long thin strips of
iron, placed as in Fig. 232, had a tendency to become unfastened at
the ends, and to curl up in a very alarming manner, which earned for
them the soubriquet of _snake heads_. Although iron was only used to a
limited extent in the first instance, it was soon found to be a much
more suitable material for a tram-path than the best timber. As a next
progressive step we find that the tram-plates were made entirely of
iron, of full width for the wheel-tyres, and with a guiding flange to
keep the wheels on the proper track. In some cases the guiding flanges
were placed inside the wheels, as in Figs. 229 and 230, and in others
outside, as in Fig. 231. With the former plan a thicker covering of
gravel or broken stones could be laid down to protect the sleepers
under the horse-path.

These solid tram-plates were made of cast-iron, that metal being
considered the most convenient for manufacture and the least liable to
suffer loss from rust and oxidization. Another advantage of the
cast-iron was that broken tram-plates could be melted down and recast
at a moderate cost.

Long lengths of these cast-iron plate tramways were laid down in this
country and abroad, and short portions of some of them remain in
existence even to the present day. They were of immense service for       185
the transportation of heavy materials, and without their adventitious
aid many valuable collieries and quarries must long have remained idle
and undeveloped. In thus providing a level, smooth, and comparatively
durable wheel-track for the waggons, these tramways became the fitting
pioneers of the great railway system which was to follow.

Notwithstanding the great superiority of the cast-iron plates as
compared with the former timber beams, much inconvenience was still
caused by gravel and dirt falling on to the wheel-track and seriously
impeding the haulage of the waggons. To overcome this difficulty the
next step taken was to remove the guiding flange from the tram-plate
and transfer it to the wheel, thus developing and introducing the
original flanged wheel. This was a most important step, and paved the
way for other improvements. The rails, or _edge rails_, as they were
at first called, were made sufficiently high to allow ample space for
the wheel-flanges to clear the ground, and were secured to cast-iron
chairs placed on wooden cross-sleepers, or in some cases to stone
blocks, as shown in Figs. 233, 234, and 235. The narrow top of rail,
and its height above the horse-path, effectually prevented the
lodgment of gravel or dirt, and the flanges on the wheels ensured a
more even course. From the irregular and easily choked-up tram-plate,
the system changed to the clean rail and properly defined track.
Waggons could be hauled with greater freedom, and with less wear and
tear to themselves and to the roadway.

At this time the use of the steam-engine was becoming more general,
and a fine field was opened out for its application as a motive-power
on the tramways. Stationary engines, or _winding engines_, as they
were called, were first employed to haul the trucks by means of long
ropes passed round revolving drums, and supported at intervals by
grooved pulleys placed between the rails at suitable distances. In
this way fair loads could be conveyed, and at moderate cost; but the
system was found to be only suitable for short distances, and it had
the great drawback that horses or other motive-power were still
necessary for sorting or distributing the trucks before and after
their transit by rope haulage.

The next great advance was to place the steam-engine on wheels, to
enable it to haul and accompany the trucks. Crude and imperfect as the
primitive locomotives must have been, a very short trial of them          186
served to show that the rails of cast-iron then in use were totally
unfitted to form a trackway for the newly invented machines. The short
fish-bellied cast-iron rails were made in lengths merely to extend
from chair to chair; they possessed little or no continuity, and from
the inherent brittleness of the material they were constantly breaking
and giving way under the increased weights imposed upon them. It
became necessary to adopt a more reliable material, and attention was
naturally turned to forged or wrought iron. The suggestion once made
was promptly responded to by the iron makers. Special machinery was
designed and constructed, and very soon wrought-iron rails were
manufactured in large quantities. At first they were made very similar
in section to the fish-belly cast-iron rails, but in lengths to extend
over three or four sleepers. The increased length gave greater
stability to the road, and permitted an increase of speed. The
manifest superiority of the wrought-iron rails led to their universal
adoption, and a great impetus was thus given to their manufacture.
Improvements were made in the machinery for rolling, and more care was
bestowed in the working of the iron. Changes were made in the section
of the rails; the fish-belly form was discarded, and a double-head
type was introduced to give more lateral stiffness. At this period in
its history the capabilities of the _iron road_ began to be more fully
recognized, and the supporters of the system foresaw a great future
success, both for the conveyance of passengers as well as goods.
Hitherto the tramroads or railroads had been used for minerals and
merchandize only, but it was now claimed that on a carefully
constructed line, and with improved locomotives and rolling-stock, it
would be possible to convey passengers more conveniently and rapidly
than by any other method.

[Illustration: Fig. 236, 237, 238, 239, 240, 241, 242, 243, 244, 245,
246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258]

Inventive minds were at work to accomplish so desirable an object, and
public enterprise was forthcoming to provide funds for the purpose.
The successful working of the first passenger line formed the dawn of
a new era in travelling, and similar lines were soon projected for
other places. The wrought-iron rails in use at this time were
generally of a double head form, and rarely exceeded 12 or 15 feet in
length. They were held by wooden pegs in cast-iron chairs, which were
secured to timber cross-sleepers or stone blocks, as shown in Figs.       188
234 and 235.

They were light in section, and it is stated that the first rails on
the Liverpool and Manchester Railway weighed only 33 lbs. per yard.

The railway system spread rapidly, and the constantly increasing
traffic of all kinds soon necessitated heavier rails. Various sections
were devised and tried on different lines, one of the main objects in
view being to obtain a steady road for the increasing speeds, as well
as one of durability. Some of these sections are shown in Figs. 236 to
258.

Sections 236 to 248 all required chairs to attach them to the
sleepers. The flange rails, 249 to 253, and bridge rails, 254 to 256,
also rail 257, were designed to rest direct upon the sleepers without
the necessity of chairs; and the Barlow rail, 258, with its great
width of 11 or 12 inches, was intended to be used without sleepers of
any kind, the gauge being secured by means of angle iron tie-bars.

Rails were rolled heavier and longer, and more care was bestowed on
the fastenings; but, notwithstanding these improvements, the
rail-joints still continued to be the weak point in the road. Even
with an extra large joint-chair and stout wooden key, there was much
vertical play at the ends of the rails, producing objectionable noise
and vibration in the running, and acting detrimentally on all the
fastenings. The introduction of fish-plates at the rail-joints, as
shown in Fig. 259, effected an improvement which cannot be overrated,
as by their adoption such security, speed, and smoothness became
attainable as were not before possible. With a pair of simple rolled
wrought-iron fish-plates, or splices, and four bolts--two through the
end of each rail--a better, smoother, and more effectual joint was
obtained than had ever been produced by the heavy cast-iron
joint-chairs. The system of fishing, or splicing, was at once admitted
to be the simplest and most direct method of joining the rails; and,
although minor detailed improvements have since been made, the
arrangement, as a principle, has never been superseded. Many miles of
fished rails were laid down with a chair, or support, placed
immediately under the joint, forming the method termed the supported
fish-joint; but experience proved that this mode of application did
not give such a good result as the suspended fish-joint, and the
latter plan has now been adopted on almost all railways.

[Illustration: Fig. 259, 260, 261, 262, 263, 264, 265, 266, 267, 268,
269, 270, 271, 272]

The experience obtained year after year in the wear of rails under        190
heavy traffic, led to continued improvements both in the method of
rolling and in the selection of the iron to form the rail-pile; one
description of iron was found more suitable for the head, or running
surface, and another for the vertical web; but, even with the best
machinery and most carefully assorted materials, high-class
wrought-iron rails were liable to lamination, and long thin strips of
iron became detached from the upper, or wearing, surface. The rail was
composed of many layers of iron, and it was not always possible to
ensure that they were all thoroughly welded, or incorporated together.
As early as 1854 a few experimental solid steel rails were laid down
on some of the principal railways, and gave excellent results as to
evenness of wear and durability, but their cost of manufacture
rendered their extended use almost prohibitory.

Compound rails of steel and wrought-iron, as in Fig. 260, were also
tried on several railways, but the practical results were not such as
to lead to a very extended adoption. In preparing the _pile_ for a
compound rail, suitable wrought-iron bars were placed to form the
lower member or flange, the web, and part of the head, and a slab of
steel was placed on the top to form the upper portion of head, or
wearing surface of the rail. It was intended that in the process of
rolling these distinct layers were to be incorporated together, to
form the section shown in Fig. 260. Doubtless many good wearing rails
were manufactured on this system, but the inherent difference of the
two materials, steel and iron, rendered it very difficult to ensure
such uniform incorporation as would withstand the constant pounding
under heavy, fast traffic. It was not until some years later that the
process of the Bessemer Converter was discovered and perfected, by
means of which steel can be produced in large quantities far more
rapidly and at much less cost than by any other method hitherto
adopted. The introduction of this process for making steel caused a
complete revolution in the material for rails. Steel which had
previously been excluded on account of its cost, could now be supplied
at a moderate price, and, from its compact and homogeneous character,
promised a very much longer wearing life than the best wrought-iron
rails that had ever been rolled. Experience has shown that these
promises have been fully verified; wrought-iron rails are things of
the past, steel rails have taken their place, and can now be purchased    191
at a less price per ton than the iron rails of twenty years ago.

It is interesting to note that out of the many varied sections that
have been designed, some of which are shown in the sketches described,
only two have practically survived--the bullhead rail and the flange
rail. The bull-head rail, Fig. 261, has grown out of the original
double-head rail, which had both the top and bottom members made to
the same section and weight, with the object that, when the upper
table had become so much worn as to be unfit for further use, then the
rail could be turned, and the other table, or head, brought into
service. Experience, however, proved that turned rails formed a most
uneven and unsatisfactory road, the long contact with the cast-iron
chairs resulted in serious indentations at the rail-seats, rendering
the rails totally unfitted for smooth running. In practice, therefore,
it has been found better to restrict the running wear to one head
only, and to give increased sectional area to that head, and, at the
same time to diminish the sectional area of the lower member to a
corresponding extent, but to retain the same width, so as to obtain a
full bearing surface on the cast-iron chair. Steel bull-head rails are
now adopted on nearly all the principal lines at home, and on several
of the leading lines abroad.

The flange rail, Fig. 265, was designed to give a broad, direct
bearing on the sleepers, and thus avoid the necessity of using chairs.
Rails of this section have been laid down on many of our lines at
home, and are very largely used on the Continent, in the United States
of America, and in our colonies generally. This section is, also,
nearly always adopted for narrow-gauge railways. Having fewer parts,
it makes a cheaper road than the bull-head rail, but is not considered
so strong or suitable for heavy and fast traffic. Comparing the two
rails shown in Figs. 261 and 265, each having exactly the same size
and sectional area in the head, it will be seen that there is more
material in the lower member, or flange, of the one rail than there is
in the lower member of the other; the weight per lineal yard being 79
lbs. for the former and 75 lbs. for the latter. But this small excess
in the weight and cost of the flange rail falls very short of the cost
of the cast-iron chairs and wooden keys necessary for the bull-head
rail.

Up to the years 1870-1875, it was the common practice to make the top,
or wearing surface of the rail, comparatively round, as shown on the      192
typical sections, Figs. 263 and 267. The effect of this sharp-curved
outline was to limit the first wearing, or contact surface to a narrow
strip along the head of rail, causing a tendency to groove or form
hollows in the treads of the wheel-tyres. As the rail wore down, the
upper surface assumed a much flatter curve, more closely assimilated
to the section of the wheel-tyre, and giving better results for
regular wear under heavy traffic. Profiting by this experience, the
rails of the present day are made much flatter on the head than they
were formerly, as will be noted from the sections shown on Figs. 261,
266, and 269, which represent types of rails now actually in use on
some of the principal railways.

In designing a rail for any given line, the section and weight of the
rail must necessarily be influenced by the weight of the rolling-stock
passing over it, and the amount of the traffic it has to sustain.

The engine, being the heaviest vehicle in the train, will give the
measure of the greatest weight on one pair of wheels. Engines vary
considerably on different lines, ranging from ten tons to eighteen
tons or more on one pair of driving-wheels, according to the
description of work to be performed.

Very often secondary or branch lines, with comparatively light
traffic, have steep gradients, necessitating engines as heavy as on a
main trunk line; but the number of trains on the former may not exceed
twenty per day, while on the latter they may amount to one hundred and
fifty or two hundred. It is evident that the rail which would last for
very many years under the small traffic, would have a very short life
under the frequent traffic. Hence the reason why it is found expedient
to give a large increase of material in the heads of rails carrying
the heavy, constant train service of many of our main lines.

Figs. 261, 262, and 263 are sections of rails in use on lines having
heavy engines and fast trains, but with a comparatively small daily
train service, and Figs. 264, 266, 267, and 268 are sections of rails
carrying the heavy, fast, and incessant traffic of some of our leading
lines.

On lines having small traffic, slow speeds, easy gradients, and
comparatively light engines, a reduced section of rail may be adopted;
but in doing so it is well to allow for any probable future
development of traffic which might cause the introduction of heavier
engines.

Figs. 269 to 272 show sections of rails varying from 72 to 60 lbs. per    193
yard, also a section of a 45-lb. steel flange-rail, much used on
3-foot narrow-gauge railways.

Valuable and interesting statistics have from time to time been
recorded, with a view to ascertain the average life of a steel rail,
by obtaining the number of million tons of train load which it would
sustain before it became worn down to such an extent as to be no
longer of service on the line. It will be readily understood that the
rate of wear of a steel rail will depend not only on the weight and
section of the rail itself, but on the class of rolling-stock, and the
description of traffic it has to carry. It will also be largely
affected by the circumstances of whether the line is on a level or on
an incline.

The writer has had careful measurement taken of the wear of the steel
flange-rail (Fig. 265), 79 lbs. per yard, and the result shows that
with a traffic not exceeding twenty-four goods and passenger trains
per day, one-tenth of an inch was worn off the top of the rail in ten
years on the comparatively level portions of the line; but that the
same amount of one-tenth of an inch was worn off in six years by the
same traffic, on the same district of the line, in places where the
gradients varied from 1 in 100 to 1 in 70. The heavy pounding of the
engines, and the working of the brakes tend very materially to shorten
the life of the rails on the inclines.

As now made, the steel rails manufactured under the converter process
exhibit great similarity in the analysis of their component parts; at
the same time it is well known that a slight preponderance or
reduction of one or more of the constituents will result in making the
steel hard or soft. The following statement gives the analysis of
twelve steel rails, six of which were classed as _hard_ steel, and six
as _soft_ steel:--

  HARD STEEL.--ANALYSIS OF SIX STEEL RAILS WHICH BROKE EITHER IN
               TESTING OR IN LINE.

  -----------+--------+--------+--------+--------+---------+---------
             |    1.  |    2.  |    3.  |    4.  |    5.   |    6.
  -----------+--------+--------+--------+--------+---------+---------
  Carbon     |   0·47 |   0·51 |   0·56 |   0·43 |   0·47  |   0·54
  Silicon    |   0·09 |   0·08 |   0·08 |   0·09 |   0·095 |   0·121
  Sulphur    |   0·06 |   0·06 |   0·06 |   0·06 |   0·054 |   0·056
  Phosphorus |   0·07 |   0·06 |   0·06 |   0·08 |   0·08  |   0·057
  Manganese  |   1·23 |   1·10 |   0·90 |   1·23 |   1·15  |   1·26
  Iron       |  98·08 |  98·19 |  98·34 |  98·11 |  98·151 |  97·966
             +--------+--------+--------+--------+---------+---------
             | 100·00 | 100·00 | 100·00 | 100·00 | 100·000 | 100·000
  -----------+--------+--------+--------+--------+---------+---------

  SOFT STEEL.--ANALYSIS OF SIX STEEL RAILS WHICH STOOD THE TEST WELL,     194
               AND BENT FREELY WITHOUT SHOWING ANY SIGN OF FRACTURE.

  -----------+---------+---------+---------+---------+---------+---------
             |    1.   |    2.   |    3.   |    4.   |    5.   |    6.
  -----------+---------+---------+---------+---------+---------+---------
  Carbon     |   0·35  |   0·39  |   0·37  |   0·34  |   0·35  |   0·250
  Silicon    |   0·06  |   0·07  |   0·07  |   0·08  |   0·07  |   0·069
  Sulphur    |   0·062 |   0·061 |   0·062 |   0·061 |   0·061 |   0·046
  Phosphorus |   0·061 |   0·061 |   0·061 |   0·063 |   0·062 |   0·058
  Manganese  |   0·870 |   0·875 |   0·866 |   0·864 |   0·800 |   0·636
  Iron       |  98·597 |  98·543 |  98·571 |  98·592 |  98·657 |  98·941
  -----------+---------+---------+---------+---------+---------+---------
             | 100·000 | 100·000 | 100·009 | 100·000 | 100·000 | 100·000
  -----------+---------+---------+---------+---------+---------+---------

Many rails which have been broken in the line under traffic have been
analyzed, and proved to be hard steel; while others, which have been
bent into all sorts of shapes, but not broken during accidents or
derailments, have also been tested, and proved to be of soft steel.

Some engineers are advocates for a hard steel rail, and claim for it
greater durability and longer wear; but even supposing such hard rail
should possess a slight superiority over the soft rail, it is well to
consider whether such assumed advantage is not obtained at the risk of
incurring greater liability to fracture. It must be borne in mind that
a rail, once placed in the road, is exposed to all the changes of
temperature from heat to frost, and has frequently to sustain
increased strains arising from loose sleepers, where the gravel or
ballast has been disturbed during heavy rains.

When writing a specification for steel rails, it is usual to state the
number of tons per square inch in tensile strain which the steel must
be able to sustain without fracture, and also to stipulate that some
of the rails will be tested by the falling-weight test. In the latter
test a rail is placed, say at 3 feet bearings, and in a similar
position to what it would occupy in the road, and a weight of eighteen
hundredweight, or one ton or more, according to section of rail, is
allowed to fall from a height of 9 or 10 feet, on to the rail, at the
centre between the bearings. With three blows from the given height,
the rail must not bend or deflect more than a specified amount. The
falling-weight test is, perhaps, rather a rough and ready one; but it
is always reassuring to prove that the rails will withstand such a
severe ordeal, as it must be a very exceptional circumstance in the
routine of railway working which will produce a blow or shock equal       195
in effect to the falling-weight test. The rails form such an important
part of the trackway, almost the very basis on which the traffic has
to depend for its safety, that, apart from the question of wear, no
effort should be spared to ensure their thorough soundness and
efficiency.

In modern practice rails are generally used in lengths varying from 25
feet to 30 feet. There is no difficulty in making them longer; but any
excess over the above lengths is found to be inconvenient for
transport, for handling in the line, and for making the necessary
allowance for contraction and expansion at the joints. Steel rails are
generally marked on the vertical web with the initials of the railway
company, the name of the manufacturer, and the year in which they are
rolled. This is done by cutting out the letters in the last pair of
rolls through which the rails have to pass before they are completed,
so that on the rails themselves the letters stand out in raised
characters, thus: G.N.R.I.......C. CAMMELL & C^o 1896. In this
manner the rails always carry for reference the name of maker and
date.

When comparing the relative merits of the flange-rail and
bull-head-rail permanent way, the question of strength and durability
must be considered, as well as that of economy. The flange-rail road
has undoubtedly fewer parts and fastenings, and when the flange is
wide, the sleepers sound, and the rail securely held down to the
sleepers, the result is a smooth running road. So long as the rail can
be maintained in a constant close contact with the wooden sleeper, the
running is almost noiseless, the jarring on the rails being absorbed
or taken off by the timber; but so soon as a little space or play
takes place between the spikes or other fastenings and the upper
surface of the flange, the rail obtains a certain amount of rise, or
lift, which comes into action upon the passing of every rolling load,
producing unsteadiness in the rail and a clattering noise in the
running. A flange of 5 inches, on a sleeper 10 inches wide, has a
bearing surface of 50 square inches (assuming the sleeper to be square
cut, without any wane on the edges), and this area of 50 inches is
only about half of the bearing surface on the sleeper of an ordinary
modern cast-iron chair.

Main-line locomotives have weights on the driving-wheels varying from
16 to 18 and 20 tons. Taking 18 tons as representing a common practice
for a large express engine, would give 9 tons as the weight imposed on    196
each rail by each driving-wheel Assuming this weight to be distributed
over three sleepers would give a dead weight of 3 tons per sleeper, or
134 lbs. on every square inch of the 50 square inches of surface, or
rail-bearing area, on each sleeper, without taking into account the
effect of the blow or percussion from the rolling load. The presence
of a loose sleeper throws additional weight on the adjoining sleepers,
and increases the destructive influence on the timber. The constant
application of heavy rolling loads on a small bearing area of timber
crushes and wears away the timber very rapidly. The small bearing
surface of the flange rail expedites the cutting down into the
sleeper, and as the rail beds itself further and further into the
wood, the fastenings must be driven or screwed down to follow the
flange. Spikes may be driven down, but the further they go they have a
less thickness of timber for a bed, and therefore a diminished hold.
Crab bolts are apt to become rusted or ironbound, so that they cannot
be screwed further, and must then be taken out and replaced with new
ones. The narrower the flange, the more rapidly does the rail-seat cut
down to a thickness inconsistent with safety. The sharp edge of the
flange-rail has a tendency to cut a channel in the spike, and it is
not at all an unusual occurrence to find strong square shanked
dog-spikes, which have been thus cut into to the extent of a third or
even half their thickness. The comparative narrow flange places the
spikes at great disadvantage in point of leverage for holding down,
and this weakness is soon made manifest, particularly on curves, where
additional crab bolts or other devices are rendered necessary to
counteract the tendency of the rail to rock and tilt over sideways.
When the head of the rail cannot be kept in its proper position, the
gauge becomes widened, and an irregular sinuous motion takes place in
the running of the train. This drawback has been found to be a serious
matter where light narrow flange rails have been adopted to carry
comparatively heavy, short wheel-base engines. In some cases
wrought-iron sole-plates, or even cast-iron bracket-chairs, have been
introduced to give more bearing surface on the sleeper and increased
support to the rail, but neither of the two methods give the same
simple complete hold to the rail that is obtained by the cast-iron
chair for the bull-head rail.

On the other hand, the modern cast-iron chair for the bull-head rail      197
has at least double the bearing surface on the sleeper to that of the
flange-rail seat, so that under the same circumstances of rolling load
as above described, the weight of 134 lbs. per square inch would be
reduced to half, or 67 lbs. The greater length given to the chair
effectually prevents any rocking action on the part of the rail, and
reduces to a minimum any lifting action on the spike. A good fitting
chair--especially when keyed on the inside--provides a most effectual
support to the rail both vertically and laterally, and maintains the
rail to accurate gauge. By giving proper clearance space at the tops
of the chair-jaws, a bull-head rail can be taken out by simply driving
out the wooden keys, and a new rail inserted without in any way
disturbing the chairs or spikes. To change a flange rail necessitates
the slackening and removal of a large number of the spikes and crab
bolts.

As the sleepers under the chair road suffer less from the crushing of
the timber, they have a much longer life in the line, and remain
serviceable until they are incapacitated from decay. This is a very
important item in places where timber sleepers are expensive. The
steadiness of the chair prolongs the efficiency of the spikes.

As the actual wearing portion of the rail is the head, or wheel
contact surface, a liberal area--consistent with the expected
traffic--must be given to that part, whether for a bull-head rail or a
flange rail. By comparing the two sections, Figs. 273 and 274, the one
for an 85-lb. bull-head rail, and the other for a 100-lb. flange rail,
it will be seen from the dotted lines that the heads of each rail are
almost identical, the difference of 15 lbs. being disposed of in the
flange of the heavier rail. Practically, therefore, we have 15 lbs.
per yard extra weight of steel in the rail, on the one hand, as
against the cast-iron chairs and steadier permanent way on the other.

For lines where the traffic is small, weights light, speeds low, and
economy of construction imperative, the flange-rail permanent way will
be very suitable.

The writer has had long mileages of each description of permanent way
under his charge, both at home and abroad, for many years, and the
result of his experience has shown that, although a fairly good road
may be made with flange rails, still, for constant, heavy, fast
traffic, the bull-head rail with cast-iron chairs makes a much
stronger, more durable, and better permanent way than any flange
railroad.

[Illustration: Fig. 273, 274]

Briefly summarized, the principal advantages and disadvantages of the     199
two kinds of rails stand as follows:--

                            ADVANTAGES.

        Bull-head Rail.                        Flange Rail.

  Large bearing surface of chair       Fewness of parts, and less
  upon the sleeper, and greater        cost.
  stability of the rail.
                                       Smaller quantity of ballast
  Longer life of wooden sleeper.       required to cover up the foot
                                       of rail.
  Impossibility of rail tilting
  over outwards.                       More lateral stiffness than
                                       the bull-head rail.
  Facility for changing a rail
  without disturbing the
  fastenings in the sleepers.

  Easier to maintain, owing to
  less disturbing strains on the
  fastenings.

  A bull-head rail is more
  readily set or laid to follow
  line of curve.

  In most cases the one set of
  chairs will serve for a second
  set of rails.

  Perfect straightness of rail:
  it is very rare to find a
  crooked bull-head rail.

  Easier to roll, and more
  likely to obtain uniformity of
  steel.

                           DISADVANTAGES.

        Bull-head Rail.                        Flange Rail.

  Bull-head Rail.                      The small rail-seat area on
                                       sleeper throws great crushing
  Greater cost.                        weight on the timber.

  More ballast required to cover       Shorter life of wooden
  up the rail.                         sleepers from the cutting down
                                       of rail-seats.
  Less lateral stiffness than
  the flange rail.                     The edge of flange cuts the
                                       spikes after a few years.

                                       The undulation of the rail
                                       under trains tends to raise
                                       the spikes, and causes lateral
                                       movement in the rails.

                                       More difficult to maintain, in
                                       consequence of greater
                                       tendency of the fastenings to
                                       work loose.

                                       Difficulty in getting flange
                                       rails straightened laterally.

                                       More difficult to set to
                                       follow regular line of curves.

                                       More difficult to roll, and
                                       less likely to obtain
                                       uniformity of steel.


Tramway Rails.--Tramways on streets or public roads are now
universally recognized as important branches of the railway principle.
Their smoothness of movement, increased accommodation, and many other
advantages as compared with the old road omnibus, render it no longer
necessary to call for special advocacy when there is a possibility of
their introduction. They occupy a position so thoroughly appreciated      200
by the public that any check on their reasonable use or extension
would be considered as detrimental to the interests of the travelling
community.

As a rule, these tramways are laid down on streets or roads previously
constructed for the ordinary road traffic, where all the preliminary
work of earth filling, bridges, drainage, etc., has already been
accomplished, and there only remains the selection and laying down of
the rails or permanent way over which the tram-cars will have to run.
The description and weight of permanent way to be adopted will depend
largely upon the weight of the cars to be used and the system of
motive-power decided upon for the haulage--whether horses, steam,
cable, or electricity.

As the portion of the streets or public roads along which the tramway
has to be laid will, in all probability, have to be occupied and
traversed by all kinds of vehicles besides the tram-cars, it is
absolutely necessary that the permanent way for the tramway should be
of such description as to require the least possible amount of
adjustment of fastenings or opening out of the roadway for repairs.
Where the entire width of the street, including the space between the
tram-rails, is paved with stone setts, the opening out of even a short
length for repairs is tedious and costly, and causes considerable
obstruction to the street traffic. It is most important, therefore,
that the rail and its fastenings should not only be strong enough for
its own tram service and the carts and drays which will pass over and
across the track in all directions, but it must possess the minimum
necessity for disturbance.

Figs. 275 to 279 are sketches of a few of the many types which have
been brought into use in various places.

Where the public roads are wide, and a space can be set apart at the
side for the special use of the tramway, the arrangement shown in Fig.
275 will be simple and efficient. It is very similar to an ordinary
railway permanent way with the ballast filled in flush with the top of
the rails. The rails are shown as flange or flat-bottom rails, fished
together at the joints, and properly secured to transverse sleepers of
wood, iron, or steel. The space between and outside the rails is
filled in with small-sized broken stone ballast or good clean gravel,
and forms an even surface, over which animals or cattle may pass
without risk of being thrown down.

[Illustration: Fig. 275, 276, 277, 278, 279]

Fig. 276 represents a system which was laid down extensively, especially  202
for horse tramways, but not proving efficient, has been superseded by
other types of a stronger and more durable description. The rail was
rolled with a continuous groove to provide clearance for the flanges
of the car-wheels, and the sides of the rail were turned down so as to
fit over the longitudinal timber sleeper, to which the rail was
secured by staple-dogs, as shown. Cast-iron chairs, spiked on to
wooden cross-sleepers, held the longitudinal sleepers in position. The
wooden sleepers were favourable for smooth running, but the section of
the rail, practically a light channel-iron laid on the flat, was most
unsuitable for carrying weight or for making a proper joint.
Experience proved this road to be very difficult to maintain in good
order for easy traction. The staple-dogs worked loose after a little
time, and the rail, having scarcely any vertical stiffness, rose and
fell during the passage of every car-wheel, resulting in most uneven
joints and a clattering roadway.

With the view to obtain a stronger and more permanent support for the
rail than the longitudinal timber sleeper last described, various
forms of cast-iron chairs were devised. Fig. 277 represents one of
these patterns. The rail, which is of T-section with a
continuous wheel-flange groove, is secured to the cast-iron chair by
the cross-pin, as shown. Although this cross-pin may in time work a
little loose, it cannot work out, being kept in position by the
paving-setts on each side. The cast-iron chairs are placed at
convenient distances, and being set in a bed of concrete, do not
require cross-sleepers or tie-bars. This type makes a strong road, but
the rail-joints cannot be made so even or efficient as with the more
modern form of rail.

Rail manufacturers are now able to roll a section of rail combining
the vertical stiffness of the ordinary flange, or flat-bottom, rail
with the running-head and continuous wheel-flange groove, considered
the most suitable for heavy tramway traffic. The introduction of this
section of rail has contributed greatly to the increased efficiency
and durability of the permanent way for street traffic; and as the
ends of the rails can be secured by ordinary fish-plates, there is the
great acquisition of even joints and increased smoothness in the
running of the tramcars. This rail can be rolled of various weights to
suit the rolling loads. On some tram-lines a moderately heavy section
has been adopted, and secured to transverse sleepers of rolled iron or
steel laid on a bed of concrete. On others similar rolled metal
sleepers have been used, but laid longitudinally. For some descriptions   203
of traffic a much heavier section of rail has been used, having a base
sufficiently wide to provide ample bearing on a bed of concrete
without the intervention of either transverse or longitudinal
sleepers.

Fig. 278 is a sketch of the modern rail as laid down on a rolled steel
transverse sleeper, the rail being held in position either by
turned-up clips, wedges, bolts, or any of the devices in use for
similar duty in the rolled-steel sleepers for ordinary railway
permanent way.

Fig. 279 shows a modern rail of a heavier section, with a wide flange
resting direct on a continuous bed of concrete. The gauge is
maintained by bar-iron tie-bars placed vertically so as to fit in
between the courses of the paving-setts, the ends being forged and
screwed to pass through holes in the vertical web of rail, and secured
in position by nuts. Both in this, and in type Fig. 278, ordinary
fish-plates are adopted at the rail-joints, as indicated by dotted
lines.

In the last two examples above described all the materials are of the
most durable description, and the least liable to wear or decay, but
it will be necessary to guard against making the fastenings and the
bars too light for the duty they have to perform. There should be
ample material in the head of the rail to allow of a fair wearing
down, and the continuous flange groove should be sufficiently deep to
meet this wearing away without causing the wheel-flanges to strike the
bottom of the groove.

[Illustration: Fig. 280, 281, 282, 283, 284, 285, 286, 287, 288, 289,
290, 291]


Fish-plates.--In the first examples of the newly invented
wrought-iron fish-plates they were made to the depth to fit in between
the upper and lower tables of the rail, as shown in Fig. 280, a small
space or clearance being left between the inner sides and the vertical
web of the rail. Ordinary nuts and bolts were used in most cases, but
in some instances one of the fish-plates was tapped, as in Fig. 281,
forming one long continuous nut, and in others both fish-plates were
tapped, as in Fig. 282, and right and left handed bolts were used.
Neither of the two arrangements of tapped fish-plates proved
sufficiently successful as to lead to their general adoption. When the
bolts became rusted in, or iron-bound, it was found to be almost
impossible to remove them without permanently damaging the
fish-plates. With the four right and left handed bolts the operation
of tightening, or removing, the fish-plates was very tedious, as each
bolt had to be turned a very little at a time, one after the other.       205
Independent bolts and nuts, either of iron or steel, are now
universally used; plain holes, with sufficient allowance for work and
expansion, being punched or drilled in the rails and fish-plates.

For many years the depth of the fish-plates continued to be made the
same as the space between the upper and lower members of the rail, as
shown in Fig. 280; but with the heavier loads and higher speeds of our
modern railway working it has been found necessary to strengthen the
joints by providing deeper or stiffer fish-plates, as shown in Figs.
283, 284, and 285. For bull-head rails the fish-plates have been
brought down underneath the lower table, and in some cases extended
down sufficiently far to admit of a second set of fish-bolts under the
rail. For flange rails some fish-plates are used simply of the form of
angle irons, and others have the angle portion carried out beyond the
end of the flange, or foot of rail, and then turned down vertically to
a depth of an inch or more below the rail. The latter makes a very
strong fish-plate.

Fish-plates, like rails, are now almost universally made of steel.

The efficiency and durability of a fish-plate depends materially upon
its angle of contact with the under side of the head of the rail, and
the extent of its contact surface. It would be an error to suppose
there is little or no wearing away in fish-plates, as in reality there
is very considerable wear, and especially in rails of lighter section.
If the under side of the head of rail has a curved outline, as in the
rail in Fig. 287, there will be some difficulty in ensuring a perfect
fit in the fish-plates; the curve of the one may not quite correspond
to the curve of the other, and the contact surface will be very small.
It is better to make these contact surfaces in straight lines, and to
a wide angle rather than to an acute angle. In Fig. 288 the under side
of head and corresponding top of fish-plates are set at an acute
angle, and fish-plates to this pattern will soon wear up to the
vertical web of rail, and cause a loose noisy joint.

In Fig. 284, showing a different type of rail, the contact surfaces
are set at a very much wider angle, and will allow much more wear
before the fish-plates can work close up to the web of the rail.

When once the fish-plates are close up to the web, the best and           206
tightest bolts cannot prevent the vertical play in the ends of the
rails.

A hammering sound will announce each successive drop of the wheels
from one rail to the other, more distinctly, perhaps, at slow speeds
than when travelling quickly, but existing equally under both
conditions. The unpleasant jarring sensation is annoying to the
passengers, and has a straining, loosening effect on all the bolts and
fastenings. Unless the fish-plates have a thorough continuous bearing
against the upper and lower shoulders of both the rails, it will be
impossible to obtain a smooth even joint. A road may have good rails,
good chairs, and good sleepers, but if the fish-plates are worn and
loose the entire permanent way may be pronounced faulty, and all on
account of a minor defect which can be easily remedied. With strong,
properly fitting fish-plates, the position of the joints should be
imperceptible when passing over them in a train.

The writer has had many miles of line where the fish-plates have worn
hard up to the rail web. In cases where the rails were good, with the
prospect of a long life, new fish-plates of suitable section have been
provided. In others, thin wrought-iron plate liners, 1/16 or 1/12 of
an inch thick, have been inserted, as in Fig. 291, so as to bring the
plates well out from the web, and allow the fish-bolts and fish-plates
to exercise the free gripping action which is absolutely necessary to
prevent the vertical rising and falling of the rail-ends during the
passage of a rolling load. Fish-plate liners of the above description
have given excellent results, and have restored the efficiency of the
fish-plates for several years.


Chairs.--All rails which partake of the double head section, or have
a base not wider than the head, require supports or carriers to attach
them to the sleepers, and to secure them in their proper upright
position. In the days of the original _edge rails_, at the
commencement of the railway era, these supports were very
appropriately termed _chairs_, and this name has now been adopted in
all parts of the world. Cast-iron is the most suitable material for
railways chairs, being much cheaper in cost and less liable to loss or
deterioration from rust than wrought-iron. Cast-iron chairs can be
formed to suit any section of rail, and from the nature of the
material they cannot be bent or twisted out of shape so as to
interfere with the gauge or cant. They may break during an accident or
derailment, but the fracture can be detected at once, and the broken      207
chair quickly replaced.

The chair performs the very important duty of distributing the weight
of the rolling load on the upper surface of the sleeper. If the under
side or base of the chair is small, and the rolling load large, the
chair will very rapidly wear or imbed itself into the wood of the
sleeper, shortening the life of the latter in a very palpable manner.
The short narrow chair naturally gives less stability than the larger
and broader chair. The chair shown in Fig. 292, which was much used
for 75 lb. rails some twenty years ago, has much less base area and
stability than the chair shown in Fig. 293, adopted for rails of a
similar weight in the present day. The former had a bearing surface on
the sleeper of only 53 square inches, as compared with 89 square
inches in the latter. The base area of the chair must be in proportion
to the weight it has to carry and distribute, and it would be false
economy to stint the surface area of one of the details which
influences so materially the stability and durability of the permanent
way.

As will be seen in Figs. 294, 295, and 296, the chairs at present used
for 80, 85, and 90 lb. rails have a much larger bearing surface than
the chair shown in Fig. 292.

With the wider chair, a much longer and better seat can be given to
the under table of rail, and a greater length of jaw for holding the
wooden key. The longer the rail-seat the steadier the rail and the
smoother the running.

The keys are generally made of hard wood, sometimes compressed by a
special process, cut slightly taper, or wedge, shape, and driven in
between the jaw of the chair and the vertical web of the rail. On some
railways the key is placed outside the rail, as in Fig. 297, and on
others inside the rail, as in Fig. 298. The latter method possesses
many advantages over the former. The outer jaw of the chair can be
brought well up to the under side of head of rail, giving the rail
more lateral support and better means of preserving the correct cant;
and, as in this chair the outer jaw permanently fixes the gauge, the
working out of one or more of the keys does not leave the rail exposed
to be forced outwards and widen the gauge, as in the case with dropped
keys in outside keying. Another and very important advantage of inside
keying is that platelayers, when inspecting the road by walking
between the rails, can readily examine the keys on both sides.

[Illustration: Fig. 292, 293, 294, 295, 296, 297, 298, 299, 300, 301,
302, 303, 304, 305, 306]

Chairs have been made, as in Fig. 299, with a recess in the rail-seat,    209
to hold a piece of prepared wood, or other suitable semi-elastic
material, the object being to provide a rest, or cushion, softer and
more yielding than the cast-iron. The idea looks well in theory, but
in practice the pounding on the rail compresses or crushes the wood
lower and lower into the recess, slackened keys have to be tightened,
and when the wood has been worn or crushed away down to the level of
the stop ribs, A, A, the under side of rail has no longer any
seat, or rest, beyond the two narrow ribs of cast-iron. These afford
such a very limited support that the rail becomes notched, and
produces a very rough clattering road. It is a very simple matter to
take out an old key and put in a new one, but to replace a wooden
cushion in a chair recess involves the entire removal of either the
rail or the chair. Chairs with wooden cushions have not been adopted
to any great extent, the tendency of modern practice being to reduce
as far as possible the number of parts of the permanent way, and to
provide those parts with ample bearing or contact surfaces.

Although the general practice has been to cast the chairs in one
piece, chairs have been made in two pieces, as in Fig. 300, fastened
together and to the rail by a bolt passing through the latter, the
castings being secured to the sleeper with spikes. At first sight this
pattern of chair appeared to possess some features in its favour. The
castings were simple, keys were dispensed with altogether, and the
under side of rail was not in contact with the cast-iron. A short
experience, however, proved that the drawbacks far outweighed the
apparent advantages. Holes for the through-bolts had to be punched at
fixed distances in the rails, and although this could be readily done
at the works, for the general use on the line it was necessary to
resort to the tedious process of drilling by hand for a large number
of holes on curves, and for rails cut to form _closers_.


Sleepers.--Wood possesses so many suitable qualities that we can
readily understand why it was early selected as the proper material
for sleepers. It can be cut to any size and shape, holes can be bored,
spikes can be driven, and bolts can be screwed into it without any
difficulty and without causing injury to the timber, while the
semi-elastic nature of wood absorbs the vibration of the rails and
fastenings, and provides a sound-deadening seat so conducive to smooth
running. Its only drawback is that it is perishable from wear and         210
decay. Were it not for this defect, railway sleepers of wood might be
considered as simply perfect.

With a view to greater permanency and durability, stone sleepers were
tried. These consisted of square blocks of good hard stone, measuring
about 2 feet wide each way and 12 inches thick. Holes were cut in the
stone, and plugs of hard wood inserted. The cast-iron chairs were then
placed on the top of the blocks, and the iron spikes driven through
the chair-holes into the wooden plugs. The elements of permanency were
there certainly, but a rougher road it would be impossible to
conceive. The stone was solid and unyielding, there was a total
absence of softness and elasticity, and the harsh noisy effect
produced when running over the stone-block road very soon became
intolerable. Stone-block sleepers were found to be a failure, and were
all removed. On some of our old lines, numbers of them, with the chair
marks plainly visible, may be still seen in loading banks, buildings,
sea walls, and other works for which they were never originally
intended, but for which their size and weight render them very
appropriate.

Wooden sleepers are used in two forms, transverse and longitudinal. In
the former, as in Fig. 301, the sleepers not only carry the rails, but
also preserve the gauge; in the latter as in Fig. 302, the
longitudinal sleepers only support the rails, additional timbers and
strong fastenings being necessary to maintain the gauge.

Longitudinal sleepers have been used to a large extent for bridge
rails, it being supposed that with the broad continuous sleeper a
lighter and shallower rail could be adopted, which would be equally
efficient as a heavier rail on cross-sleepers. Excellent running roads
have been made with longitudinal sleepers, notwithstanding the
difficulty of making a good bridge-rail joint; but it is well to bear
in mind that almost all the lines which originally adopted this form
of permanent way have since reverted to the ordinary cross-sleeper
road. The longitudinal sleeper road is an expensive road to lay down
and maintain. The main pieces are of large scantling, must be of good
quality of timber, and are consequently costly. The cross-pieces, or
transomes, must be carefully fitted and secured with heavy ironwork.
Where there is much traffic, the removal and renewal of one of the
long timbers is much more difficult than the renewal of several ordinary  211
cross-sleepers. Again, decay may take place on only one portion of a
main timber, but there is no alternative but to remove the entire
piece.

For gauges varying from 4 feet 8½ inches to 5 feet 3 inches,
cross-sleepers are cut to the length of 8 feet 11 inches, and are
generally rectangular in section, as in Fig. 303, measuring 10 inches
in width by 5 inches in thickness. On some of the lighter railways
with small traffic, sleepers are often used only 9 inches wide by 4½
inches thick, while occasionally on some lines, and in places where
there is exceptionally heavy and constant traffic, sleepers 12 inches
wide by 6 inches thick are adopted.

Half-round sleepers, as in Fig. 304, are used on many lines because
they are cheaper. In some cases the flat side of the sleeper is placed
downwards, and the rail or chair is fastened into an adzed seat cut in
the round side; and in the others the round side is placed downwards,
and the flat side of the sleeper carries the rail or chair. Triangular
sleepers, as in Fig. 305, have also been used, made by cutting the
blocks diagonally, so as to obtain the greatest possible width. They
were laid with the flat side upwards, and the apex downwards. They
were difficult to keep packed, and have not been adopted to any great
extent.

With the exception of a limited number of larch and fir sleepers grown
in the country, most of the sleepers for our home railways are
imported from the Baltic. They are brought over in logs, or blocks,
each 8 feet 11 inches long, some square and others circular in
section, and when sawn down the middle, each block forms two sleepers.

The preservation of timber from decay is a subject that very early
occupied the attention of engineers and all those interested in
railways. A railway sleeper is particularly exposed to deterioration
the lower portion being surrounded with moist ballast, whilst the top
portion is more or less uncovered--two different conditions in the
same piece of timber. Several processes have been tried, such as
Kyanizing, Burnetizing, Boucherizing, etc., but the system which has
given the best results, and is now almost universally adopted, is that
known as creosoting. This method consists of forcing liquid creosote,
under considerable pressure, into sleepers or railway timbers which
have been prepared or dried by ordinary natural seasoning or by
special artificial means. Creosote is a dark, oily liquid, distilled      212
from coal tar, varying in its composition according to the quality of
the coal from which it is obtained, and ranging in its specific
gravity from 11·08 to 10·28.

Creosote oils of light specific gravity were at one time in favour,
but experience proved that, to some extent, the light oils were
volatile and also soluble in water, and that heavy rains washed out
the constituents which were essential for the preservation of the
timber. On the other hand, by heating the heavy oils and using high
pressure the napthaline which is dissolved only by the heat, is forced
into the wood, fills the pores, and solidifies.

Creosote is obtainable in large quantities, at prices varying from
twopence to fourpence per gallon, according to the demand and cost of
production. Newly delivered sleepers or railway timber contain so much
sap or water that it is impossible to force a sufficient quantity of
creosote into them until they are properly seasoned or dried.

The seasoning is generally arranged by sawing each block into two
sleepers, and then stacking the sleepers on edge in tiers, leaving a
space of four or five inches between each of them for a proper
circulation of air. The sleepers should then be left for nine to
twelve months to season, although more may be necessary in some cases
if the blocks were particularly wet at the time they were sawn.

When ready for the process the sleepers are placed in the creosoting
cylinder, which is generally about 60 feet long by 6 feet in diameter
with semi-spherical ends. One of the ends is fitted with strong hinges
and fastenings, and forms the doorway. The sleepers are packed
carefully inside, and the doorway made tight. The machinery is then
set to work to exhaust the air from the cylinder and allow the
creosote to flow in amongst the sleepers. When the cylinder is full
the force-pumps are started to force in more creosote up to the
pressure prearranged and regulated by the safety-valve, in some cases
100, 110, or 120 lbs. per square inch. The creosote should be heated
to 112° or 120° Fah., to dissolve the napthaline and reduce all the
component parts to a thoroughly fluid condition.

The success of creosoting depends almost entirely upon the effectual
seasoning of the timber. Only a very small quantity of creosote can be
forced into wet or unseasoned sleepers, even with the best machinery
and exceptionally high pressures, while a thoroughly dry sleeper will     213
readily absorb from 2⅓ to 3 gallons. More could be forced into the dry
sleeper if necessary, but a little consideration will show there would
be no advantage in doing so. In railway sleepers there are two
elements of destruction at work--one the decay of the timber, and the
other abrasion or wearing away of the wood itself from the constant
pounding of the passing loads.

More particularly does this wearing-away take place with the flange,
or bridge, rails, their distributed bearing surface on the sleeper
being less than the cast-iron chairs.

A thoroughly well-creosoted 5-inch sleeper laid originally with a
thickness of 4-¾ inches in the centre of rail-seat, as in Fig. 306,
will wear down 1½ inches, the timber remaining quite sound.

The writer has had to take out thousands of sleepers where the seats
of the flange, or bridge, rails had been pounded or worn down so deep
into the wood as to leave too small a thickness of timber to carry the
rail with safety. These sleepers had to be taken out of the road, not
on account of decay, but because they were actually worn down too thin
to be of service. They had done their work well for a long series of
years, and were perfectly sound when taken out. No increased quantity
of creosote would have made them last longer, and any increased
quantity of creosote would have been waste.

Two and three quarter gallons of creosote is a very good and suitable
quantity for a 10 inch by 5 inch rectangular sleeper, but not more
than half this quantity can be forced in if the sleeper is wet or
unseasoned.

Sleeper-blocks are generally cut from the upper part of the tree, and
do not therefore consist of the best portion of the timber, yet
sleepers made from the soft, coarse-grained Baltic wood, properly
creosoted, will last from twelve to eighteen years in the line in this
country, while uncreosoted they would perish from decay in six or
seven. The benefit is great when, by adding from eightpence to a
shilling for the cost of creosoting, the life of the sleeper may be
doubled or trebled. Of course, there are countries, like the far west
of America, where the lines pass through vast forests, and where
sleepers may be had for the mere cost of cutting. Creosoting in those
places would be out of the question, and would cost four or five times
the value of the plain sleeper. It is found, also, that in tropical
countries and in dry climates at high altitudes creosote loses its        214
efficiency, and in those districts the best creosoted soft-wood
sleeper perishes from a species of dry rot in three or four years.
Where wood sleepers have to be used in tropical climates it is better
to obtain them from the timber of the district, although in many cases
suitable trees are difficult to procure and the cost of land transport
is very heavy.

The soft cushion-like effect of a sound, properly packed wooden
sleeper contributes so largely to form an easy, smooth-running road,
that so long as they can be obtained at a moderate cost, and are
fairly durable, wooden sleepers will always be preferred to those of
any other material. The great question will be the supply. Creosoting
and other wood-preserving processes have done much to prolong the life
of sleepers, but the rapidly increasing extent of mileage throughout
the world, together with the enormous number of sleepers required
annually for maintenance or renewals, must before very long severely
tax the powers of supply.

In the great timber-producing territories the axe is often heard, but
the planter is rarely seen. Vast forests are cleared away, and their
sites transformed into busy towns or cultivated lands; and unless some
great change takes place, and planting be carried out on a large
scale, some other material will have to be adopted for this important
item of our permanent way.

Appearances would indicate that at no very distant date iron or steel
will take a conspicuous part in the formation of future railway
sleepers.

More than thirty years ago several descriptions of cast-iron sleepers
were introduced into notice and tried on some of our leading home
railways. Cast-iron was at that time considered more suitable for the
purpose than wrought iron, as it was very much less costly in price,
and could be readily worked into any desired form or size, with the
advantage that the castings would all be duplicates of one another.

[Illustration: Fig. 307, 308, 309, 310, 311, 312, 313]

Figs. 307 to 313 show some of the types that were designed and laid
down in the road. In Fig. 307 the sleeper and chairs were all cast
together in one piece; the rail was held in its place by wooden keys,
and the gauge of the line was maintained by transverse wrought-iron
tie-bars. The sketch represents one of the sleepers used at the
rail-joints, and has three chairs, the larger one in the centre being
for the support of the ends of the rails. This arrangement was the        216
same as was then in use on the ordinary wood-sleeper road, where an
extra large chair was placed at the rail-joints, and was the most
approved method for many years before fish-plates were introduced. The
intermediate sleepers were shorter, and had only two chairs.

Fig. 308 represents a long, flat, cast-iron sleeper made in two
halves, bolted together just below the under side of rail at each of
the three chair-seats. The rail was gripped and held in position
without the use of wooden keys. This being a joint sleeper, three
chairs were used, as in Fig. 307. Only two chairs were used on the
intermediate sleepers.

Figs. 309 and 310 are somewhat similar, but the circular one is higher
and more cup-shaped than the other of oval form. The oval pattern has
two small recesses for holding two small hard-wood cushions. The
circular holes shown in the sides of the sleepers were intended to
facilitate the packing, or tamping, of the light sandy ballast.

Fig. 311 represents a rectangular cast-iron sleeper, as used for the
flange rail. The rail rests on cast-iron cross-ribs, bevelled to give
the proper cant, and is held in position by the tie-bar bolt and
clip-piece, as shown. The small projecting lug, formed on the under
side of sleeper, fits into a corresponding notch in the tie-bar, and
keeps the sleepers to gauge. The tie-bar passes through the loop end
of the same bolt which secures the rail, and is held up tight against
the under side of sleeper.

Figs. 312 and 313, both the same in principle, possessed features
which appeared to give great promise. They were simple in
construction; the rail was kept well down, and did not come in contact
with the cast-iron at any point. The long wooden wedges, which fitted
into the rough or serrated sides of the casting, acted as a cushion to
the rail, and were intended to sink deeper into the recess as the
super-imposed weight increased, or the wood became thinner from
shrinkage. In practice, however, it was found that these sleepers were
not the success that was anticipated.

It was soon observed that sand and fine particles of gravel from the
ballast worked their way into the lower part of the recess, and became
so compact as to prevent the wooden wedges working further down to
increase their grip on the rail. Even when the recess was kept free
and clear of sand, the enormous pressure exerted by the wooden wedges
broke the iron at A, although an extra thickness was given to that        217
part of the section. The cast-iron was exposed to the greatest strain
at the point where it was the least capable of offering resistance.

Much ingenuity was displayed in many of the patterns brought forward,
but in dealing with a hard unyielding material like cast-iron, it is
difficult, if not impossible, to impart any soft, elastic effect; and
the different systems of cast-iron sleepers failed to become popular
on our home railways, on account of the noise and vibration when
trains passed over them. Another objection was the great multiplicity
of parts required in many of the types, and the constant and severe
strain produced on the fastenings on the passing of every wheel. The
bolts might be made tight at first, but the incessant shaking would
work them loose, the threads became stripped, and the rails ceased to
be held in a proper and secure position.

The cast-iron sleeper road was considered unsuitable for the heavy and
fast traffic of our home lines, and was ultimately all taken up and
replaced with wooden transverse sleepers. At the same time, there is
no doubt that cast-iron sleepers have been of great value in India and
tropical climates, where timber sleepers were not only scarce, but
perish very rapidly. Very large numbers of them have been laid down
abroad of patterns very similar to those shown in Figs. 309, 310, and
311, and have done good service for many years. They are not affected
by rain or heat, but, unfortunately, being castings, are liable to
considerable annual loss from breakage.

Improvements in plate-rolling machinery, and in appliances for bending
and stamping wrought-iron, have materially assisted in developing the
introduction of wrought-iron and steel sleepers. Cast-iron and
wrought-iron are, in the abstract, hard and non-elastic as compared
with wood; but whereas cast-iron can only be made into fixed,
unyielding shapes, wrought-iron and steel can be worked into forms
that possess a certain spring-like effect, which not only enables them
almost entirely to resist fracture, but also imparts a measure of
elasticity to the permanent way.

The simplest form of wrought-iron sleeper would be a plain, flat
plate, to which the chair, or rail-bracket, would be attached; but as
this form would have bearing surface only, without any lateral hold on
the ballast to keep the rails to line, it could not be adopted.

During the last few years very many types of wrought-iron and steel       218
sleepers have been introduced, and nearly all of them of the
transverse-sleeper pattern, formed out of rolled plates; the sides,
and in some cases the ends also, are bent, or turned down to obtain a
hold in the ballast. Where bull-head or double-head rails are used,
cast-iron chairs, or wrought-iron bracket chairs, are bolted, or
otherwise secured to the upper surface of the sleeper, a layer of
felt, tarred paper, or other soft material being placed between the
two metal surfaces. Where flange rails are used, they are fastened to
the sleepers either by bolts, clamps, or clips raised up out of the
iron sleeper, and bent over to hold tightening keys. Rolled transverse
sleepers can readily be bent, or set in the centre to give the proper
cant at the rail-seat; and in some types the sleepers are pressed in
the machines, so as to be narrower towards the centre, and with a
deeper turnover, to obtain increased stiffness.

In Figs. 314 to 319 are shown some of the patterns which have been
brought out, laid down in actual practice, and in use at the present
time.

From the fact that wrought-iron and steel sleepers have been laid down
in so many places where cast-iron sleepers were discarded or refused a
trial, it is evident that the former are considered to have qualities
which the latter did not possess. Rolled iron or steel sleepers are
coming more and more into use, especially on foreign or colonial
railways. So long, however, as good, well-creosoted timber sleepers
can be obtained for our home railways at prices from 3_s._ 8_d._ to
4_s._ 8_d._ each, and last from fourteen to twenty years, there is
little probability that they will be supplanted by iron sleepers at
double the cost. But abroad the circumstances of cost and durability
are different, and there the rolled iron or steel sleepers, which will
outlive two or three sets of wooden ones, must claim advantages which
cannot be overlooked. The difficulty will be in the fastenings, the
mode of attaching the rails to the sleepers. The constant hammering of
metal upon metal, resulting from the vibrations of every passing load,
will quickly wear or loosen bolts, rivets, or wedges, and the
fastenings which will prove the most efficient will be those that are
the simplest and most readily adjusted.


Fastenings.--Figs. 320 to 335 illustrate some types of the principal
fastenings used in connection with the chair road, and with
flat-bottomed or flange rails.

[Illustration: Fig. 314, 315, 316, 317, 318, 319]

The fish-bolts, Figs. 320 and 321, are of a form which is in very         220
general use both for steel bull-head rails and steel flange rails. By
making the neck square or pear-shaped, to fit into corresponding hole
in the fish-plate, the bolt is prevented from turning round when the
wrench or spanner is applied to tighten the nut. A channel or groove
is sometimes rolled on the outside of fish-plate to grip bolts made
with square heads. Some engineers adopt two nuts, others prefer one
nut of extra depth. Washers are used in some cases, but are not
universal. With a deep rail it is preferable to place the nuts inside,
so that the platelayer inspecting his length can see both rows of nuts
as he walks along between the rails. With shallow rails the nuts must
be placed outside and the cup-heads inside, to give ample clearance to
the wheel-flanges.

Fish-bolts are subject to very severe work. Heavy rolling loads
passing over the rail-joints--frequently at very high speeds--bring
into play all the gripping power of the fish-bolts to maintain a firm
support of the fish-plates to ends of rails, and the constant action
of pressure and release produces a loosening or unscrewing motion in
the bolts which is very difficult to counteract. Loose fish-bolts
cause clattering joints and uneven road, and unless promptly remedied,
the screw threads are soon destroyed and bolts rendered useless. Many
devices have been invented to prevent or check this loosening of the
bolts; one of the methods, and a very simple one, consists of a plain
steel bolt with a steel lock-nut, made as shown in Fig. 322. As will
be seen from the section, one-half of the nut is tapped of the same
size as the bolt, and the remainder with deep-locking threads. The
first half of the nut is readily screwed on to the bolt, but
considerable force must be exerted to screw on the portion having the
deep-locking threads; practically the second half of the nut has to
cut a new or deeper thread for itself when screwing round the bolt.

[Illustration: Fig. 320, 321, 322, 323, 324, 325, 326, 327, 328, 329,
330, 331, 332, 333, 334, 335]

The slits or grooves at the angles of the nuts form four distinct
cutting edges for shaping the deep threads. As the upper part of the
lock-nut is divided by the grooves into four separate or detached
segments, these segments will be forced slightly open or outwards
during the action of cutting the deep thread on the bolt, and from
their natural tendency to return to their original position they must
exercise a strong gripping power on the bolt. This combined operation
of cutting the deep threads and of forcing open the upper or detached     222
segments, give an enormous holding and retaining power to the
lock-nut, and enables it to withstand the train vibrations for a very
long time without any perceptible slackening. In case of line repairs
the nut can be readily unscrewed, and taken off the bolt.

Round iron spikes, as in Figs. 323 and 324, and round wooden trenails,
as in Fig. 325, are both used for fastening cast-iron chairs to the
sleepers. The spikes are made with a slightly taper neck, of size
rather less than the hole in the chair, to avoid risk of breaking the
casting when driving the spike down. Trenails are made out of
well-seasoned hard wood, and are compressed by machinery. When driven
into the sleeper, they expand by exposure to the atmosphere, and hold
the chair very securely in position; but being only wood and of very
small scantling, they are subject to early decay. The head, which is
the only part in sight, may be perfectly sound, while the part between
the chair-seat and top of sleeper may be quite rotten and useless. It
would be very risky to depend upon trenails alone; one spike at least
should be used to every chair. In some cases an extra large trenail is
used with an augur-hole down the centre, through which either an iron
spike is driven or a bolt is passed and screwed into a crab-nut on the
under side of the sleeper. This arrangement will work well for a time,
but there will be a great deal of play in the spike or bolt when the
trenail becomes much decayed.

The spikes represented in Figs. 326, 327, and 328, are much used with
flange rails. They are square in section, and finished with either
blunt or sharp points, as shown. The top of spike is made with a
doghead and side-lugs to facilitate the easing or withdrawal when
necessary for renewals of sleepers, or alterations in line. By
inserting the curved double claw end of a platelayers’ crowbar, the
spike can be raised without injuring the sleeper; but if it is
required to be driven into the same sleeper again, a new hole must be
bored, as the old hole will be too slack to be of any service.
Augur-holes must be bored in the sleepers for the above spikes. For
new roads, these holes can be bored by machinery when cutting the
grooves for rail-seats; but when carrying out alterations or repairs,
a large number of spike-holes must be bored by hand-augurs, an
operation both slow and laborious. With the hand-boring there is the
danger that the hole may not be made deep enough, owing to the workman’s  223
endeavour to avoid damaging the point of his augur by forcing it
entirely through the sleeper, and bringing it in contact with a stone.
Augur-holes bored wide to gauge will remain out of gauge, and although
the spike may be driven down firm in its position, a space will be
left for play between the rail-flange and spike.

Fig. 329 is a sketch of a dog-spike for flange rails which the writer
has used for many years both abroad and at home, and which can be
driven without any boring at all. The back of this spike is made
perfectly straight, half of the front side is made parallel to the
back, and the remainder is tapered down to a chisel point not
exceeding 1/16 of an inch thick, the entering edge on the face being
narrowed down to 3/8 of an inch in width. Three jags or spurs are cut
on each side of the tapered portion, or twelve in all, and add greatly
to the holding power. Not only can this spike be driven without any
boring, but it possesses the additional advantage that in driving it
down its taper or wedge-like shape causes it to drift hard up to the
edge of the flange of rail, an element of great value in securing the
exact gauge of line. With these spikes permanent-way laying can be
carried on very rapidly, and they are especially valuable when making
alterations, as augurs for spike-boring can be dispensed with
altogether.

Wood screws with square heads similar to Fig. 330 are sometimes used
for fastening flange rails to wooden sleepers. They are passed through
holes punched or drilled in the flanges of the rails, and are intended
to preserve the gauge as well as secure the rails to the sleepers.
Experience has shown that these wood screws possess very limited
holding power. The screwed portion of the bolt cuts but a very
imperfect and weak holding thread in the soft wood of an ordinary
sleeper, moisture insinuates itself into the bolt-hole, rusting the
bolts and decaying the surrounding timber, and in a very short time
the bolts become loose and incapable of holding the rail down firmly.
As permanent-way fastenings wood screws are very inferior to crab
bolts.

Crab bolts, as in Fig. 331, may be made either with square or
hexagonal heads, and with three spur-nuts or four spur-nuts, as in
A or B. The length of the bolts will depend upon the thickness of
the sleeper or timber-work through which they have to be inserted. The
bolt is pushed down through the hole bored in the sleeper, and the
crab-nut put on from underneath. With a few turns of the bolt, the        224
crab-nut is brought close up to the under side of the sleeper, the
spur-points become embedded in the wood, and hold the nut firmly in
position during subsequent tightening of the bolt. Crab bolts are
extensively used with flange or flat-bottomed rails, and also in
switch chairs and in crossings. A large number of flange rails are
used with one hole through the flange at each end of rail, and a crab
bolt passed through the hole and through the sleeper next to the
joint, as shown in Fig. 332. This system checks the creeping of the
rails by effectually securing or anchoring each rail to two of the
sleepers. As there is always a tendency for these rails to crack
through to the outside at the flange-holes, it is very desirable to
have as few holes as possible. The two above described will be found
sufficient for all practical purposes. To avoid punching or drilling
more holes in the flanges of the rails, additional or intermediate
crab bolts can be used by means of the fang clips shown on Fig. 333.
The crab bolt is passed through the fang clips and through the sleeper
close up to the flange of rail, and by screwing it round in the
crab-nut under the sleeper the fang-clip is pressed down until the two
spurs are driven into the timber, and the rail held securely in its
place and to gauge. Intermediate crab-nuts and fang-clips should
always be used in pairs, one on each side of the rail. Possessing more
holding-down power than ordinary spikes, they are particularly
valuable on sharp curves.

In some cases flange rails are laid in small cast-iron saddles, or
chairs, as shown in Fig. 334, one end of the rail-seat having a recess
to prevent the rail tilting upwards and outwards. An ordinary spike
may be used for the inside end of chair, and a crab bolt with bent
washer for the other. Unless the fastenings can be kept always tight,
the above arrangement makes a very noisy, clattering road, as there
are so many metal surfaces in contact, and so little to deaden the
vibration. For narrow flange rails carrying heavy rolling load, chairs
may be necessary to increase the bearing surface on the sleeper, but
with rails having flanges five inches wide and upwards, it is better
to let the flange rest direct on the wood of a properly grooved
sleeper, and thus obtain a smoother and less noisy road.

On exceptionally sharp curves, wrought-iron or steel tie-bars, as in
Fig. 335, are sometimes used to maintain the line to gauge. They may
be made out of bars 3 inches wide by ½ an inch thick, turned over at      225
the ends to grip the outside flanges. Being made to exact template,
they have to be threaded on to the rails before spiking down, and are
placed between the sleepers at distances from 7 to 10 feet apart.


Laying Permanent Way.--To preserve a good line and level to the
permanent way, it is absolutely necessary that the road-bed should be
kept thoroughly drained. If provision be not made for quickly carrying
away the rain-water, and if it be allowed to collect under and around
the sleepers, the action of the passing trains will work the finer
particles of the packing into the consistency of soft mud, which will
be gradually squeezed away, leaving the sleepers imperfectly supported
and insecure. A loose sleeper involves a depression in the rails, and
a corresponding lurch in the vehicles of the train, and a series of
these depressions may produce such an oscillation in the train as to
cause it to leave the rails.

The height or space from formation-level to rail-level is generally
about 1 foot 9 inches for a flange railroad, and about 2 feet for a
chair railroad.

Figs. 336 and 337 show cross-sections of both descriptions of road as
laid down for a double line in cutting. The same arrangement applies
to similar roads laid down in embankment, merely omitting the
side-drains or water-tables. The bottom layer of ballast or road-bed
should consist of good hard, quarried, or broken stones, each 6 inches
deep, set on edge, firmly and closely hand-packed, forming a
foundation through which the rain-water can be quickly carried away.
On the top of this bottom pitching should be placed a 6-inch layer of
broken stone ballast or strong clean gravel, of which none of the
stones should be larger than will pass through a 2-inch ring. When the
sleepers and rails have been laid on this second layer, and properly
packed to line and level, the top ballasting, or boxing, of either
broken stones or strong clean gravel, should be filled in to the form
and extent specified. Where broken stones are used for the top
ballasting none of them should be larger than will pass through a
1½-inch ring.

Broken stone ballast should only be made from the hardest and soundest
description of rock or boulders, so that, however small the particles,
they will remain sharp and clean.

[Illustration: Fig. 336, 337, 339, 338, 340, 341, 342, 343, 344]

There are many kinds of rock which appear hard and compact when first
excavated, but upon exposure to the weather undergo a complete change,    227
developing into soft masses containing too much clay to allow the
water to pass through readily. Where rock is scarce and gravel
plentiful, the lower layer may be made of the heavier or coarser
gravel, leaving the finer gravel for the upper layer, or boxing; but
there is no doubt that the broken stone pitching makes the most
efficient bottom layer. No gravel ballast should be used which is not
free from clay or earthy sand.

Wherever there are particles of earthy matter, sufficient to furnish
nourishment for vegetable growth, weeds will quickly spring up, and
once established are most difficult, if not impossible, to eradicate.
The presence of weeds checks drainage, and gives an untidy appearance
to the line, besides constantly occupying a large portion of the
platelayers’ time in their removal.

Clean cinders, free from dust or earth, are much used for upper
ballast and boxing, and being lighter than gravel, are specially
applicable for soft boggy ground. Burnt clay, broken into small
pieces, has been largely adopted in districts where both rock and
gravel were difficult to obtain. Chalk, furnace-slag broken small,
crushed brick and sand, are frequently used as ballast. Sand is
objectionable where there is high-speed traffic, as the finer
particles rise in the form of dust and deposit themselves on the
vehicles and machinery of the train.

The water-tables, or side drains in the cuttings, should be cut below
the formation level, and to a depth or width sufficient to take away
all rain-water, or water arising from springs. Where the material of
the cutting is of a loose friable nature, it may be necessary to
protect the sides of the water-tables with low dry stone walls, as in
Fig. 338; or glazed earthenware pipes may be laid, as in Fig. 339,
with open joints, or with grate openings at regular intervals. In some
cases substantial side-walls and invert are requisite to carry away
the flow of water.

Timber sleepers intended for the flange railroad should have the
rail-seats grooved by machinery to ensure perfect accuracy in the
position of the grooves, and in the angle or inclination of the
rail-seats. Fig. 340 is a side view of part of a sleeper grooved to
receive a flange rail. The presence of the grooves materially
facilitate the laying of the rails to gauge, but must not be allowed
to interfere with the constant use of the platelayer’s gauge. In a
similar manner the timber sleepers for the chair road frequently have     228
the spike-holes bored to template by machinery, as indicated on Fig.
341. Steel or iron sleepers are delivered with the recesses for rails,
and holes for bolts or fastenings formed complete by machinery.

The distances apart of the sleepers will be regulated in a great
measure by the weight of the rails and the description of the traffic.
Where light rails are intended to carry heavy engines the sleepers
must be laid closer together than would be necessary for heavy rails.
The joint being the weakest part of the rail, it is usual to put the
sleepers closer together at that place, with a view to gain additional
support, to assist the fish-plates in preserving as much as possible a
firm unyielding surface at the rail-joint.

Fig. 343 shows an arrangement of sleepering largely adopted for steel
flange rails 26 feet long, and weighing 79 lbs. per yard. The length
of a rail is more a question of convenience of handling, facility of
transhipment, and general use, than of actual manufacture. There is no
difficulty in rolling rails up to 50 feet in length, or more; but very
long rails are extremely ungainly things to move about, and are more
exposed to receive permanent bends or kinks in unloading, besides
requiring greater spaces at the joints to allow for contraction and
expansion.

Fig. 344 is an example of sleepering for a chair railroad, for steel
bull-head rails 26 feet long, and weighing 85 pounds per yard.

Line stakes and level pegs must be put in at suitable distances to
guide the platelayers in laying the rails to the correct line and
level, and on the curves the proper amount must be marked off for the
super-elevation of the outer rail.

When the second layer of ballast has been spread for its full width
and depth the sleepers can be distributed, and the rails or chairs
spiked down to the correct gauge. Before putting on the fish-plates
spaces must be left at the ends of the rails to allow for contraction
and expansion, the amount depending upon the temperature at the time
of laying down the rails. As the rails will expand, or increase in
length, with the heat, it is necessary to allow more space for
expansion for rails laid down in the cold, or winter months. On our
home railways rails are very rarely laid down when the temperature is
lower than 25° F., or higher than 125° F., and this range of 100° may
be considered as covering all the variations likely to occur in
ordinary practice. The greater portion of the permanent-way laying is     229
carried on when the temperature is between 40° and 75°. The results of
very carefully conducted experiments show that an increase of
temperature of 1° F. will cause an iron or steel bar, or rail, to
expand or lengthen to the extent of seven one-millionths of its
length. Working this out for a range of 100° F. would give an increase
in length of seven hundred one-millionths, which would be equal to an
extension of 0·2184 of an inch in a 26-foot rail. For our home
railways, therefore, a space of 5/16 of an inch will be found amply
sufficient to meet the variations in length between the extremes of
winter and summer, for a rail from 26 feet to 30 feet in length. Too
much allowance for expansion is detrimental to the rails, because
where the spaces are excessively large the wheels drop into the hollow
and hammer or spread the ends of the rails.

The fish-bolts should not be completely tightened up until the
permanent way is thoroughly set, and packed to its finished line and
level.

On straight line the rail-joints should be laid square and opposite to
each other. Permanent-way laying with broken joints is rarely adopted,
except on curves or station-yards.

On curves the joints of the inner rails gain on the joints of the
outer rails to the extent of--

  radius + gauge
  -------------- × length of rail.
      radius

The amount of this gain, or lead, is adjusted by cutting off a portion
of the end of the inner rails at certain intervals.

Assuming the fish-bolt holes to be spaced as shown on Fig. 342, then,
when the inner rail is leading to the extent of 2 inches, a piece 4
inches long is cut off, as shown by dotted lines, leaving the original
second fish-bolt hole to serve as first or end fish-bolt hole, and a
new or second bolt-hole is drilled by hand at A. This method sets back
the joint 2 inches from the square, and the lead is allowed to go on
again until it becomes necessary to cut off another piece of 4 inches.
Another mode is to have a proportion of the rails rolled 2 or 3 inches
shorter for use on the curves.

On curves of a 1000 feet radius and upwards, the rails should be laid
to the normal gauge, but on curves of lesser radius the gauge may be
slightly increased, and as much as ¾ of an inch allowed on a curve of
500 feet radius.

The amount of cant, or super-elevation, to be given to the outer rail     230
on curves must be regulated by the speed of the train and the gauge of
the line. Many formulæ have been compiled to determine the necessary
amount of super-elevation, but experience has shown that by some of
them the calculated amounts were excessive. Possibly during past years
too much cant has been given in many cases. The following simple
formula approaches very closely to practical experience--

  (velocity in miles per hour)^2 × gauge in feet   {the super-elevation
  ----------------------------------------------- ={ of outer rail
                    radius in feet × 1·25          { in inches.

For high-speed trains uniformity of cant is of the utmost importance,
more so even than the exact amount. Any irregularity in the
super-elevation of the outer rail, sometimes high and sometimes low,
will produce a dangerous swaying movement in the train, which, if not
promptly checked, would lead to derailment.

More injury is done to curves by spreading, arising from rigid
wheel-bases of engines and tenders, than from any want of
counteraction to centrifugal force.

When a long length of permanent way has been linked in, rails spiked
to gauge, and fish-plates bolted together, the platelayers can proceed
to the final adjustment to line and level in accordance with the
stakes and pegs provided for their guidance. The setting to exact line
is effected by means of long pointed round iron crowbars, which are
struck forcibly into the ballast alongside the rails, and serve as
powerful hand-levers to pull or push the rails to the right or left as
directed by the foreman standing some distance back at one of the
line-stakes. The men with the crowbars pass from rail-length to
rail-length, until a long stretch of road has been pulled into correct
line.

The adjustment to rail-level is done by first packing up the sleepers
to the correct height at the various level-pegs, and then packing up
the intermediate sleepers so that the surface of the top of the rails
forms one uniform even line from level-peg to level-peg. On new lines
it is usual to pack a little high in the first instance to allow for
the subsidence or compression which invariably takes place on the
passage of heavy trains over fresh ballast.

The form or contour line of the top ballast will vary according to        231
circumstances. In station-yards it is usual to fill in the ballast
almost up to the level of the top of the rails for the convenience and
safety of the men who are constantly moving about marshalling the
carriages and waggons. Out on the open line between stations, the
ballast on some railways is filled in up to rail-level, while on
others it is only filled in up to the tops of the sleepers, leaving
the rails and chairs quite clear of the ballast. On others, again, the
ballast is filled well up to the rails and channelled in the centre,
as shown on the sketches Figs. 336 and 337. Channelling the centre of
the road reduces the quantity of ballast per mile, ensures good
drainage, and also stability by not permitting any central support to
the sleepers. By covering up the lower table and sides of rails the
noise is reduced to a minimum, vibration is absorbed, and a more
silent road is the result. The contact with the ballast also preserves
the rail from the extremes of temperature. Where the ballasting is not
channelled there is some risk of the sleepers breaking in the middle.
The constant packing of the sleepers just under the rails has a
tendency to drift some of the ballast inwards towards the middle of
the sleeper, forming a hard compact mass, and this mass, acting as
fulcrum, throws considerable strain on the middle of the sleeper when
the trains pass over and depress the ends. Where the ballast is filled
in level with the rails on top of sleepers it should be loosened
occasionally in the middle to prevent it becoming too hard.

Connections with the rails of the main line will have to be made in
various forms to suit the circumstances of the joining lines or
sidings.

Fig. 345 shows a simple double-line junction.

[Illustration: Fig. 345, 346, 347, 348, 349, 350, 351, 352, 353, 354,
355, 356]

Fig. 346 shows an example of what is termed a _flying junction_, or a
junction of two double lines arranged in such a manner as to cause the
least interruption to a constant train traffic passing UP and
DOWN over both lines. Upon referring to Fig. 345 it will be seen
that a train from F, turning off at the points E and proceeding to
G, must block, or close for traffic the section ABC during its
passage over that line towards G. With a crowded train-service the
blocking of both UP and DOWN main lines for the working of one
train would cause much interruption, and to obviate such delay the
_flying junction_ is substituted. Fig. 346 shows how a train from F
is turned off at the points J and proceeds on to K, where by means
of a bridge it passes either over or under both main lines, and           233
continues on to G without in any way interfering with the train
service on ABC.

Fig. 347 is an ordinary plain siding or _turn-out_, including the
necessary throw-off or trap-points and short dead end.

Fig. 348 is an ordinary _cross-over road_ from DOWN main line to
UP main line, and _vice versâ_.

Fig. 349 is a double cross-over road, generally termed a _scissors_
cross-over.

Fig. 350 is a simple through cross-over road from DOWN main line
to siding alongside UP main line.

Fig. 351 is a similar arrangement of through cross-over road with the
addition of a pair of slip points at S to make a connection with the
UP main line, thus combining the facilities of the ordinary
cross-over and through cross-over road.

Fig. 352 shows a set of three throw-switches with all the sliding
tongues placed side by side; and Fig. 353 shows another arrangement of
three throws with the sliding-rails of the second set of switches
placed just behind the heel of the first set of switches. The latter
method works very well where there is sufficient length for the
purpose.

Fig. 354 shows a square crossing, where one line of railway crosses
another line of railway on the same level.

Fig. 355 shows a connection with a siding by means of an ordinary
carriage or waggon turn-table.

Fig. 356 shows a set of “runaway” points which are sometimes placed in
the main line at the top of an incline close to a station, the object
being to intercept or throw off any portion of a train which may have
become detached, and which would, if unchecked, run away back down the
incline. By means of a weighted lever or spring the points are set to
the normal position of _open_ to the siding, and as they are
“trailing” points for the running road they are readily closed by a
passing train. One or other of the above forms of connections, or a
combination of them, will meet all the requirements which usually
occur in railway work.

Fig. 357 is an enlarged sketch of an ordinary cross-over road, and
Fig. 358 of a double or _scissors_ cross-over.

[Illustration: Fig. 357, 358]

Fig. 359 shows a _single-slip_ point connection, and Fig. 360 a
_double-slip_ point connection. In places where slip connections can
be introduced they add greatly to the facilities for train movements      235
without curtailing the available standing-room for vehicles on the
lines and sidings. They are simple in construction, do not require
crossings, and in many cases save a complete cross-over road. At the
same time slip connections can only be laid down where the angle of
the intersecting lines is sufficiently flat to admit of a connecting
curve of workable radius.

Fig. 361 is an enlarged sketch of a set of ordinary 15-foot switches
or points. By placing them about the middle of the stock rails the
joints of the latter are kept well beyond the sliding rails, and the
road is held firmly together. It is necessary to place the sleepers
closer together at the switches to allow for the reduction in section
of the sliding rails, which results from planing them down to the
requisite shape. By substituting two long timbers for the ordinary
sleepers at the points of the switch rails, as shown on the sketch, a
more efficient support is obtained for the switch-box or crank in the
case of rod-worked switches, and the working distance from the rails
is accurately maintained, irrespective of any packing or pulling of
the road. In the sketch a steel bull-head rail is shown on one side,
and a steel flange rail on the other, each bolted to an ordinary
cast-iron switch chair. Switch chairs are sometimes made of plates of
wrought-iron or steel, forged to the correct shape, and riveted
together. They are, however, much more costly than cast-iron chairs,
and deteriorate more quickly from corrosion.

[Illustration: Fig. 359, 360]

Fig. 362 is an enlarged sketch of an ordinary crossing similar to the
one indicated at C (Fig. 359), and composed of a cast-steel
reversible block. The ends and lugs, L, L, are formed to suit the
connecting rails and fish-plates, as shown in the cross-sections. The
casting is secured to the crossing timbers by bolts passing through
the side lugs, S, a cast-iron packing-washer, W, being placed
between the lug and the timber to ensure a solid seat and avoid
rocking. A very important point in the construction of these block
crossings is to have the groove or flange-path sufficiently deep to
prevent the striking or touching of the flange of a much-worn tyre. A
well-made, carefully annealed steel-block reversible crossing is very
smooth in the road, and has a long life. It is all in one solid piece;
there are no parts to work loose or spread; the wear of the running
surface is very uniform, and when the one side is much worn down,
there is the other ready for service. The writer has had many of these
steel-block reversible crossings in use under heavy and fast traffic      237
for six and eight years without turning.

Fig. 363 shows an ordinary crossing made of steel bull-head rails
secured in strong cast-iron chairs; and Fig. 364 is a similar crossing
made of steel flange rails. In some cases the two rails forming the
V are welded together at the point B, and in others they are
riveted or bolted together. Fig. 365 shows a diamond or through
crossing similar to the one indicated at D, Fig. 359, made of steel
bull-head rails and chairs.

Crossings are constructed in a variety of forms, whether on the
principle of the cast-steel block, or made out of ordinary steel
rails; and the above sketches merely illustrate some well-recognized
types which experience has proved to be efficient and durable in the
road. The angles of the crossings will depend upon the divergence of
the intersecting lines to be connected; ordinary crossings, to the
angle of 1 in 10, work in for very general use in station-yards, but
many are required of angles varying from 1 in 6 to 1 in 14, and in
some cases 1 in 16.

As a rule, engineers endeavour as far as possible to avoid using
ordinary crossings flatter than 1 in 12, or diamond crossings flatter
than 1 in 9, because the gap between the running rails becomes very
considerable beyond those angles. At the same time, there are many
cases of ordinary crossings of 1 in 16, and diamond crossings of 1 in
12 and 1 in 13 laid down in exceptional places, and which have carried
heavy and fast traffic for many years. All crossings should be well
protected with wing rails and guard rails, as shown on the sketches.

Fig. 366 illustrates a method of bringing the UP and down lines of a
double line of railway close to each other, and passing them over a
single-line opening bridge, or a bridge where the works for the second
line have not been completed. This arrangement avoids the necessity of
any switches, and prevents any accidents which would arise from a
misplaced switch. Each set of trains is effectually kept to its own
line of rails. With proper signalling or pilot working, the
double-line traffic can be worked over the single-line bridge without
difficulty. The writer has adopted the above arrangement in many cases
when renewing double-line bridges or viaducts where the width for
traffic working has been restricted to half of the bridge.

[Illustration: Fig. 361, 362, 363, 364, 365]

In some instances the same system has been extended to the carrying of    239
four lines of rails over a double-line bridge, as shown on Fig. 367.

The principal tool used by platelayers for lifting the permanent way
is a long iron-shod wooden lever, as shown in Fig. 368. The point of
the lower end is pushed under the sleeper, and the curved shoulder
placed on a large stone or piece of wood as a support, and then by
pulling down the upper end of the lever the road can be lifted to the
height required. Screw lifting-jacks of various kinds are also used
for the same purpose, the foot or base of the jack resting on the
ballast, while the claws grasp the under side of the rail, and raise
it by means of the screw. With appliances which lift by the rails, the
sleepers have to be raised by the holding power of the spikes or
bolts, an operation which is apt to throw undue strain on spikes.
Where possible it is preferable to lift from the under side of the
sleepers.

Beaters similar to the one shown on Fig. 369 are used for packing the
ballast. One end of the beater is pointed like a pick, and serves to
loosen the ballast or broken stone, and the other end is made somewhat
in the hammer-head form to pack or beat the ballast under the sleeper.
With skilled men the beater is a most useful tool, speedy and
effective in its action. Held in both hands, it is raised slightly,
and then brought down sharply, the hammer-head striking the gravel or
broken stone placed alongside for packing under the sleeper. A series
of smart blows can be given with rapidity and without requiring any
great muscular effort. In some foreign countries there is difficulty
in initiating the natives to work with the ordinary beater, on account
of the stooping position necessary for its use. To meet this
difficulty the writer has in many cases substituted a packing or
tamping bar, as shown in Fig. 370. This bar, about 5 feet long, is
made of light round wrought-iron or steel, with a ring-shaped handle
at one end, and an ordinary beater head at the other. The workman
using this bar stands upright, guides the bar, held loosely, with his
left hand, and with his right gives a continuance of smart blows. This
tool works well in the hands of light active natives, who can thus
give a number of rapid strokes without much exertion.

[Illustration: Fig. 366, 367, 368, 371, 369, 370, 372]

The simple rail-bender, or _Jim Crow_, of the form shown in Fig. 371,
is much used by platelayers for giving a slight bend or set to rails
which have to be laid down on sharp curves on main line or cross-over
roads. The rail is laid across the two arms, and the screw turned round   241
and downwards by means of an iron bar lever used as a spanner or
wrench to the nut shown on the sketch. The same tool is also
serviceable for straightening rails which have become crooked or
kinked. Large and more comprehensive machines are used for bending
rails in large quantities or setting them to exact curvature, but,
being heavy and cumbersome, they are rarely taken away from the
store-yards.

Strong steel shovels of the form shown in Fig. 372 are the most
suitable for platelayers’ general use when working with gravel, sand,
or broken stones.

For driving iron spikes and wooden keys in cast-iron chairs a
long-handled hammer is the most convenient for work, and its long
swinging action produces considerable force without much actual
labour.

Road-gauges, nut-wrenches, short straight-edges, spirit-levels,
ratchet-drills, augurs, and cold setts of well-tempered steel for
cutting rails, are all required by the men engaged in laying permanent
way.

The following summaries give the estimated cost of materials alone for
one mile of steel bull-head rail and steel flange rail permanent way
of different weights. The 90-lb. steel bull-head rail is at present
the heaviest of that section laid down to any extent on our home
railways, and the chairs and fastenings are made heavy to correspond
to the rail and the traffic for which it is intended. As the rails in
the summaries become lighter, the weights of the chairs and fastenings
are decreased. As yet there are not many samples of the 100-lb. steel
flange rail; but in those places where it has been laid down it has
been supported with a liberal supply of sleepers, to obtain increased
bearing surface. With a 5½-inch flange, and a rectangular sleeper 10
inches wide, the bearing surface on the wood is only about 55 square
inches, as compared with about 100 square inches, the bearing surface
of a large cast-iron chair for a heavy bull-head rail. As previously
explained, a small bearing surface on a sleeper tends to the cutting
down into the wood, and rendering the sleeper unsafe and useless even
before it has become unserviceable from decay: hence the reason for
ample bearing surface on the sleeper. The last two summaries refer to
3-foot narrow-gauge lines. In more than one instance the 45-lb. rails
first laid down have been found much too light for the engines
required to work the traffic, and when making extensions of the system    242
65-lb. rails have been adopted. Indeed, when taking into consideration
the weight of most of the narrow-gauge engines, generally from 24 to
28 tons in working order, and their short wheel-base, it would appear
that a 65-lb. rail is the minimum which should be used both for
stability and economy in maintenance.

The summaries are prepared from examples in actual use, and represent
the number and weight of sleepers, chairs, and fastenings in each
instance. Even with the same weight of rail, the practice differs on
various lines as to the weights of the chairs and fastenings; and the
selections have been made to show a fair average. On some railways the
chairs are secured partly by tree-nails and partly by spikes, or crab
bolts; on others only spikes are used. The prices put down are the
estimated values of the materials delivered into the Permanent Way
Stores of our own home railways, and are exclusive of all costs of
freight, carriage, or distribution to the site of laying down. The
prices are only comparative, and fluctuate up or down according to the
current value of the raw materials from which the various items are
manufactured. Lighter rails and smaller fastenings cost more per ton
than those of a heavier type, as they involve more labour and
workmanship.

             STEEL BULL-HEAD RAILS (90 LBS. PER YARD).
     _Estimated Cost of Materials for One Mile of Single Line._

  -------------------------------+--------------------+----------+----------
                                 |  Weight per mile   |  Price.  |  Amount.
                                 |  of single line.   |          |
  -------------------------------+--------------------+----------+----------
                                 |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel bull-head rails, 90 lbs. |                    |          |
    per yard (30-ft. lengths)    | 141    8   2    0  |  5  0  0 | 707  2  6
  Steel fish-plates (deep),      |                    |          |
    41 lbs. per pair             |   6   10   0    0  |  6 15  0 |  43 17  6
  Fish-bolts and nuts            |   1    4   0    0  | 12 15  0 |  15  6  0
  2112 creosoted sleepers,       |                    |          |
    9 ft. × 10 in. × 5 in.       |        --          |  0  3 10 | 404 16  0
  4224 cast-iron chairs,         |                    |          |
    each 50 lbs.                 |  94    5   3    0  |  3 10  0 | 330  0  1
  8448 iron cup-headed spikes    |   3   15   2    0  | 10  0  0 |  37 15  0
  8448 tree-nails, at per 1000   |        --          |  3 10  0 |  29 11  4
  4224 oak keys, at per 1000     |        --          |  5  0  0 |  21  2  5
  -------------------------------+--------------------+----------+----------
                                                                £|1589 10 10
  ---------------------------------------------------------------+----------


             STEEL BULL-HEAD RAILS (85 LBS. PER YARD).                    243
     _Estimated Cost of Materials for One Mile of Single Line._

  -------------------------------+--------------------+----------+----------
                                 | Weight per mile    |  Price.  |  Amount.
                                 | of single line.    |          |
  -------------------------------+--------------------+----------+----------
                                 |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel bull-head rails, 85 lbs. |                    |          |
    per yard (26-ft. length )    | 134    0   0    0  |  5  0  0 | 670  0  0
  Steel fish-plates (deep),      |                    |          |
    38 lbs. per pair             |   6   17   3    0  |  6 15  0 |  46  9 10
  Fish-bolts and nuts            |   1    4   3    0  | 12 15  0 |  15 15  7
  2030 creosoted sleepers,       |                    |          |
    9 ft. × 10 in. × 5 in.       |        --          |  0  3 10 | 389  1  8
  4060 cast-iron chairs,         |                    |          |
    each 45 lbs.                 |  81   11   1    0  |  3 10  0 | 285  9  5
  8120 iron cup-headed spikes    |   3   12   2    0  | 10  0  0 |  36  5  0
  4060 tree-nails, at per 1000   |        --          |  3 10  0 |  14  4  2
  4060 oak keys, at per 1000     |        --          |  5  0  0 |  20  6  0
  -------------------------------+--------------------+----------+----------
                                                                £|1477 11  8
  ---------------------------------------------------------------+----------


             STEEL BULL-HEAD RAILS (80 LBS. PER YARD).
     _Estimated Cost of Materials for One Mile of Single Line._

  -------------------------------+--------------------+----------+----------
                                 | Weight per mile    |  Price.  |  Amount.
                                 | of single line.    |          |
  -------------------------------+--------------------+----------+----------
                                 |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel bull-head rails, 80 lbs. |                    |          |
    per yard (26-ft. lengths)    | 125   14   0    0  |  5  0  0 | 628 10  0
  Steel fish-plates (deep),      |                    |          |
    37 lbs. per pair             |   6   14   1    0  |  6 15  0 |  45  6  2
  Fish-bolts and nuts            |   1    4   3    0  | 12 15  0 |  15 15  7
  2030 creosoted sleepers,       |                    |          |
    9 ft. × 10 in. × 5 in.       |        --          |  0  3 10 | 389  1  8
  4060 cast-iron chairs,         |                    |          |
    each 40 lbs.                 |  72   10   0    0  |  3 10  0 | 253 15  0
  8120 iron cup-headed spikes    |   3   12   2    0  | 10  0  0 |  36  5  0
  4060 tree-nails, at per 1000   |        --          |  3 10  0 |  14  4  2
  4060 oak keys, at per 1000     |        --          |  5  0  0 |  20  6  0
  -------------------------------+--------------------+----------+----------
                                                                £|1403  3  7
  ---------------------------------------------------------------+----------


             STEEL BULL-HEAD RAILS (75 LBS. PER YARD).
     _Estimated Cost of Materials for One Mile of Single Line._


  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel bull-head rails, 75 lbs.|                    |          |
    per yard (26-ft. lengths)   | 117   0    0    0  |  5  0  0 | 585  0  0
  Steel fish-plates (deep),     |                    |          |
    35 lbs. per pair            |   6   7    0    0  |  6 15  0 |  42 17  3
  Fish-bolts and nuts           |   1   4    3    0  | 12 15  0 |  15 15  7
  2030 creosoted sleepers,      |                    |          |
    9 ft. × 10 in. × 5 in.      |       --           |  0  3 10 | 389  1  8
  4060 cast-iron chairs,        |                    |          |
    each 37 lbs.                |  67   1    1    0  |  3 10  0 | 234 14  5
  12,180 iron cup-headed spikes |   5   8    3    0  | 10  0  0 |  54  7  6
  4060 oak keys, at per 1000    |       --           |  5  0  0 |  20  6  0
  ------------------------------+--------------------+----------+----------
                                                               £|1342  2  5
  ------------------------------+--------------------+----------+----------


             STEEL BULL-HEAD RAILS (70 LBS. PER YARD).                    244
     _Estimated Cost of Materials for One Mile of Single Line._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel bull-head rails, 70 lbs.|                    |          |
    per yard (26-ft. lengths)   |  110  0    0    0  |  5  0  0 | 550  0  0
  Steel fish-plates (deep),     |                    |          |
    32 lbs. per pair            |    5 16    0    0  |  6 15  0 |  39  3  0
  Fish-bolts and nuts           |    1  2    0    0  | 12 15  0 |  14  0  6
  2030 creosoted sleepers,      |                    |          |
    9 ft. × 10 in. × 5 in.      |       --           |  0  3 10 | 389  1  8
  4060 cast-iron chairs,        |                    |          |
    each 34 lbs.                |   61 12    2    0  |  3 10  0 | 215 13  9
  8120 iron cup-headed spikes   |    3  3    2    0  | 10  0  0 |  31 15  0
  4060 oak keys, at per 1000    |       --           |  4 10  0 |  18  5  5
  ------------------------------+--------------------+----------+----------
                                                               £|1257 19  4
  --------------------------------------------------------------+----------


             STEEL BULL-HEAD RAILS (65 LBS. PER YARD).
     _Estimated Cost of Materials for One Mile of Single Line._

  -------------------------------+--------------------+----------+----------
                                 | Weight per mile    |  Price.  |  Amount.
                                 | of single line.    |          |
  -------------------------------+--------------------+----------+----------
                                 |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel bull-head rails, 65 lbs. |                    |          |
    per yard (26-ft. lengths)    |  102  3    0    0  |  5  5  0 | 536  5  9
  Steel fish-plates (deep),      |                    |          |
    28 lbs. per pair             |    5  1    2    0  |  7  0  0 |  35 10  6
  Fish-bolts and nuts            |    1  1    0    0  | 13  0  0 |  13 13  0
  2030 creosoted sleepers,       |                    |          |
    9 ft. × 9 in. × 4½ in.       |       --           |  0  3  0 | 304 10  0
  4060 cast-iron chairs,         |                    |          |
    each 28 lbs.                 |   50 15    0    0  |  4  0  0 | 203  0  0
  8120 iron cup-headed spikes    |    2 19    0    0  | 10 10  0 |  30 19  6
  4060 oak keys, at per 1000     |       --           |  4  0  0 |  16  4  9
  -------------------------------+--------------------+----------+----------
                                                                £|1140  3  6
  ---------------------------------------------------------------+----------


               STEEL FLANGE RAILS (100 LBS. PER YARD).
       _Estimated Cost of Materials for One Mile of Single Line._

  -------------------------------+--------------------+----------+----------
                                 | Weight per mile    |  Price.  |  Amount.
                                 | of single line.    |          |
  -------------------------------+--------------------+----------+----------
                                 |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 100 lbs.   |                    |          |
    per yard (30-ft. lengths)    |  157  3    0    0  |  5  0  0 | 785 15  0
  Steel fish-plates (deep),      |                    |          |
    42 lbs. per pair             |    6 12    0    0  |  6 10  0 |  42 18  0
  Fish-bolts and nuts            |    1  5    0    0  | 12 15  0 |  15 18  9
  2464 creosoted sleepers,       |                    |          |
    9 ft. × 10 in. × 5 in.       |       --           |  0  3 10 | 472  5  4
  8448 dog-head spikes           |    3  6    0    0  | 12 10  0 |  41  5  0
  704 fang clips                 |    0  8    3    0  | 13 10  0 |   5 18  2
  1408 crab bolts                |    1  6    3    0  | 12 10  0 |  16 14  5
  -------------------------------+--------------------+----------+----------
                                                                £|1380 14  8
  ---------------------------------------------------------------+----------


               STEEL FLANGE RAILS (79 LBS. PER YARD).                     245
       _Estimated Cost of Materials for One Mile of Single Line._

  ------------------------------+--------------------+----------+----------
                                |  Weight per mile   |  Price.  |  Amount.
                                |  of single line.   |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 79 lbs.   |                    |          |
    per yard (26-ft. lengths)   | 125   0    0    0  |  5  0  0 | 625  0  0
  Steel fish-plates (deep),     |                    |          |
    37 lbs. per pair            |   6  14    1    0  |  6 10  0 |  43 12  8
  Fish-bolts and nuts           |   1   4    0    0  | 12 15  0 |  15  6  0
  2030 creosoted sleepers,      |                    |          |
    9 ft. × 10 in. × 5 in.      |       --           |  0  3 10 | 389  1  8
  6496 dog-head spikes          |   2  10    3    0  | 12 10  0 |  31 14  5
  812 fang clips                |   0  10    0    0  | 13 10  0 |   6 15  0
  1624 crab bolts               |   1  10    3    0  | 12 10  0 |  19  4  5
  ------------------------------+--------------------+----------+----------
                                                               £|1130 14  2
  --------------------------------------------------------------+----------


               STEEL FLANGE RAILS (74 LBS. PER YARD).
     _Estimated Cost of Materials for One Mile of Single Line._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 74 lbs.   |                    |          |
    per yard (30-ft. lengths)   | 116   5    3    0  |  5  0  0 | 581  8  9
  Steel fish-plates (deep),     |                    |          |
    30½ lbs. per pair           |   4  15    3    0  |  6 10  0 |  31  2  5
  Fish-bolts and nuts           |   1   1    0    0  | 12 15  0 |  13  7  9
  1936 creosoted sleepers,      |                    |          |
    9 ft. × 10 in. × 5 in.      |       --           |  0  3 10 | 371  1  4
  6336 dog-head spikes          |   2   9    2    0  | 12 10  0 |  30 18  9
  704 fang clips                |   0   8    3    0  | 13 10  0 |   5 18  2
  1408 crab bolts               |   1   6    3    0  | 12 10  0 |  16 14  5
  ------------------------------+--------------------+----------+----------
                                                               £|1050 11  7
  --------------------------------------------------------------+----------


               STEEL FLANGE RAILS (65 LBS. PER YARD).
    _Estimated Cost of Materials for One Mile of Single Line._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 65 lbs.   |                    |          |
    per yard (30-ft. lengths)   | 102   3    0    0  |  5 10  0 | 561 16  6
  Steel fish-plates (deep),     |                    |          |
    27 lbs. per pair            |   4   4    3    0  |  7  5  0 |  30 14  5
  Fish-bolts and nuts           |   1   0    0    0  | 13  0  0 |  13  0  0
  1936 creosoted sleepers,      |                    |          |
    9 ft. × 10 in. × 5 in.      |       --           |  0  3 10 | 371  1  4
  6336 dog-head spikes          |   2   9    2    0  | 12 10  0 |  30 18  9
  704 fang clips                |   0   8    0    0  | 13 10  0 |   5  8  0
  1408 crab bolts               |   1   6    3    0  | 12 10  0 |  16 14  5
  ------------------------------+--------------------+----------+----------
                                                               £|1029 13  5
  --------------------------------------------------------------+----------


               STEEL FLANGE RAILS (60 LBS. PER YARD).                     246
     _Estimated Cost of Materials for One Mile of Single Line._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                  |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 60 lbs.   |                    |          |
    per yard (30-ft. lengths)   | 94    5    3    0  |  5 10  0 | 518 11  7
  Steel fish-plates (deep),     |                    |          |
    25 lbs. per pair            |  3   18    2    0  |  7  5  0 |  28  9  2
  Fish-bolts and nuts           |  1    0    0    0  | 13  0  0 |  13  0  0
  2112 creosoted sleepers,      |                    |          |
    9 ft. × 10 in. × 5 in.      |       --           |  0  3 10 | 404 16  0
  7040 dog-head spikes          |  2   15    0    0  | 12 10  0 |  34  7  6
  704 fang clips                |  0    8    0    0  | 13 10  0 |   5  8  0
  1408 crab bolts               |  1    6    3    0  | 12 10  0 |  16 14  5
  ------------------------------+--------------------+----------+----------
                                                               £|1021  6  8
  --------------------------------------------------------------+----------


               STEEL FLANGE RAILS (50 LBS. PER YARD).
     _Estimated Cost of Materials for One Mile of Single Line._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 50 lbs.   |                    |          |
    per yard (30-ft. lengths)   | 78   11    2    0  |  5 15  0 | 451 16  1
  Steel fish-plates (deep),     |                    |          |
    22 lbs. per pair            |  3    9    1    0  |  7 10  0 |  25 19  5
  Fish-bolts and nuts           |  0   18    0    0  | 13 10  0 |  12  3  0
  2112 creosoted sleepers,      |                    |          |
    9 ft. × 9 in. × 4½ in.      |       --           |  0  3  0 | 316 16  0
  7040 dog-head spikes          |  2    7    1    0  | 13  0  0 |  30 14  3
  704 fang clips                |  0    6    1    0  | 14  0  0 |   4  7  6
  1408 crab bolts               |  1    2    0    0  | 13  0  0 |  14  6  0
  ------------------------------+--------------------+----------+----------
                                                               £| 856  2  3
  --------------------------------------------------------------+----------


               STEEL FLANGE RAILS (65 LBS. PER YARD).
  _Estimated Cost of Materials for One Mile of Single Line (3-ft. gauge)._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 65 lbs.   |                    |          |
    per yard (30-ft. lengths)   |102    3    0    0  |  5 10  0 | 561 16  6
  Steel fish-plates (deep),     |                    |          |
    27 lbs. per pair            |  4    4    3    0  |  7  5  0 |  30 14  5
  Fish-bolts and nuts           |  1    0    0    0  | 13  0  0 |  13  0  0
  2288 creosoted sleepers,      |                    |          |
    6 ft. × 9 in. × 4½ in.      |       --           |  0  2  3 | 257  8  0
  7744 dog-head spikes          |  2   17    0    0  | 12 10  0 |  35 12  6
  704 fang clips                |  0    7    2    0  | 13 10  0 |   5  1  3
  1408 crab bolts               |  2    2    0    0  | 12 10  0 |  26  5  0
  ------------------------------+--------------------+----------+----------
                                                               £| 929 17  8
  --------------------------------------------------------------+----------


               STEEL FLANGE RAILS (45 LBS. PER YARD).                     247

  _Estimated Cost of Materials for One Mile of Single Line (3-ft. gauge)._

  ------------------------------+--------------------+----------+----------
                                | Weight per mile    |  Price.  |  Amount.
                                | of single line.    |          |
  ------------------------------+--------------------+----------+----------
                                |tons. cwt. qrs. lbs.| £  s. d. |  £  s. d.
  Steel flange rails, 45 lbs.   |                    |          |
    per yard (26-ft. lengths)   | 70   14    1    0  |  5 15  0 | 406 12  0
  Steel fish-plates (deep),     |                    |          |
    16 lbs. per pair            |  2   18    0    0  |  7 10  0 |  21 15  0
  Fish-bolts and nuts           |  0   18    0    0  | 13 10  0 |  12  3  0
  2233 creosoted sleepers,      |                    |          |
    6 ft. × 8 in. × 4 in.       |       --           |  0  1 10 | 204 13 10
  7308 dog-head spikes          |  2   14    0    0  | 13  0  0 |  35  2  0
  812 fang clips                |  0    5    0    0  | 14  0  0 |   3 10  0
  1624 crab bolts               |  0   18    0    0  | 13  0  0 |  11 14  0
  ------------------------------+--------------------+----------+----------
                                                               £| 695  9 10
  --------------------------------------------------------------+----------




  CHAPTER IV.                                                             248

  Stations: Station Buildings, Roofs, Lines, and Sidings.


Stations.--When selecting a site for a station, not only should due
regard be paid to the proximity and convenience of access to the town
or place to be served, but attention should be given to the gradients
of the line near the proposed station. If it can possibly be avoided,
a station should not be placed in a hollow at the foot of two
inclines, as such a position would always entail heavy work starting
trains on the ascending gradients, with the risk of sliding back into
the station again in unfavourable weather; and for arriving trains
there would be increased difficulty in properly controlling the
vehicles on the descending gradients so as to bring them to a stand in
the event of any sudden stoppage being required. With stations on a
summit, having gradients falling in each direction, the starting
trains can get away more readily, and the arriving trains have the
benefit of the rising gradient to assist them in coming to a stand.
Possibly the best selection would be a long length of level, both in
the station proper and for a considerable distance on each side; but
it is not often that such a combination can be obtained without
incurring extra expenditure. The station-yard itself should, however,
be on the level, or as nearly so as possible, for the convenience and
safety of marshalling or shunting carriages or waggons. No siding
should be laid on such a gradient as would render it possible for
vehicles to start into motion during high winds. Carriages and waggons
having good oil axle-boxes will start themselves on a gradient of 1 in
300 under the influence of a moderately strong breeze, and a slight
push will start them on a gradient of 1 in 400.

The number and arrangement of the lines, sidings, platforms, loading
banks, and other conveniences of a station, will depend upon the
description and amount of traffic to be accommodated. There is a wide     249
range from the simple village station, with its one short siding, to
the great city terminus, with its labyrinth of lines and sidings, and
its groups of platforms, offices, warehouses, and other accessories.
Each station should be laid out with a view to meet the special
requirements of the principal traffic likely to arise, whether
passenger, timber, coal, stone, cattle, or general merchandise, and
ample space should be retained to permit further enlargement and
additional sidings at any future time. If provision is not made for
the latter in the outset it will certainly lead to large expenditure
at some later date. Land adjoining a railway station is quickly
appropriated by the public on account of its proximity and convenience
for conveyance, and soon covered with store-yards, warehouses, and
other buildings, and when any portion of these have to be acquired for
station enlargements, they can only be obtained at a large cost, very
often ten times as much as the value of the original ground.

When laying out approach roads to goods or passenger stations, whether
intermediate or terminal, due importance should be given to the
advantage of making them wide, easy in gradient, and fairly straight.
A narrow, crooked access to a busy goods yard is a great impediment to
the expeditious working of a heavy traffic; and road waggons conveying
long pieces of timber or ironwork along such a route, would be very
apt to block the roadway and delay the passage of other vehicles. A
steep gradient will prevent the carriers taking full loads, and will
add to the cost and time of delivery.

[Illustration: Fig. 373]

An approach road to a large passenger station should be laid out with
a long frontage to a wide footpath to enable the numerous intending
passengers to alight conveniently from the conveyances which bring
them to the station. A portion of the footpath and carriage-way in
front of the entrance to the booking-hall should be covered over with
a light roof to provide shelter during inclement weather. The footpath
should be on the same level as the vestibule or booking-hall, so that
the public may pass at once to the ticket-office and their luggage be
wheeled on hand-barrows direct to the platform or luggage-room. Every
effort should be made to avoid introducing steps from the footpath to
the booking-hall, as they check the proper ingress of the passengers,
and are very severe on elderly persons and invalids, besides
necessitating the dilatory method of carrying each piece of the
passengers’ luggage by hand. Experience has shown the inconvenience of    251
steps to be so great that in many cases a large expenditure has
afterwards been incurred to do away with them, and bring the
setting-down footpath to the same level as the booking-hall. For a
large station the booking-hall should be spacious and well provided
with separate ticket windows for the different classes of passengers
and districts of the line; and the access or communication with the
platform should be ample and free from obstruction. Small doors and
narrow passage-ways check the movements of the passengers and create
confusion and delay.

Waiting-rooms for the different classes of passengers,
inquiry-offices, luggage-rooms, lavatories, etc., will have to be
provided according to the amount of traffic to be accommodated. In
large stations it may be necessary to have two or more groups of such
rooms to suit the different sets of platforms.

At the most important terminal stations of our home railways it is
usual to lay down the main-line arrival platforms with a cab or
carriage rank alongside, so that the passengers alighting from the
railway carriages have merely to walk across the platforms, and step
into the cabs or vehicles waiting to take them and their luggage away
from the station. This arrangement is not only a great convenience to
the passengers, but expedites the clearing of the platform and the
making way for another incoming train. It would not, however, be of
any service on continental lines, or other foreign railways, where all
arriving luggage must first be taken to the general luggage room, to
be examined by the local customs, or _octroi_ officers, before being
allowed to pass out of the station.

[Illustration: Fig. 374, 375]

Main-line departure platforms should be of ample width to allow of the
free movement of the passengers, ticket examiners, officials, and men
wheeling passengers’ luggage. The accommodation should not only be
sufficient for the normal traffic, but allowance should be made for
the large crowds which may assemble for excursion trains during the
holiday season or other occasions of national gathering. Additional or
local platforms, frequently termed _dock platforms_, may be required
for suburban trains, and may be made narrower in width, and without
cab ranks, as the passengers using them only travel short distances
and rarely have more luggage than they carry in their hands. These
dock platforms are generally made available for outgoing as well as       253
incoming trains. The lengths of the main-line or local platforms will
be regulated by the number of carriages forming a train.

Fig. 373 is a diagram sketch of a large terminal passenger station,
with main and local platforms as above described. It is merely typical
to illustrate the principle, and may be multiplied and varied to any
extent in the way of lines and platforms. In the sketch the main
groups of offices, waiting-rooms, etc., are shown at the end of the
station; but they may be equally well placed at the side, as their
actual location is principally a question of proximity or convenience
of access to some main street or thoroughfare. The lower or
platform-level rooms of such a building are mainly devoted to the
public for booking-offices, waiting-rooms, refreshment-rooms,
lavatories, offices for parcels, telegraph and inquiry, suitable rooms
being set apart for lamps, foot-warmers, guards, and porters. Above
this lower story a range of offices can be built for the use of the
principal officers and staff of the different departments of the
company.

Fig. 374 is a plan of a small terminal station on a single line of
railway, where the passenger traffic is small, and one platform is
made to serve alternately both for arrival and departure trains. The
booking-hall, waiting-rooms, offices, etc., are laid down parallel to
the line of rails, and the approach road and footpath are parallel to
the building. The platform roof extends to the outer wall, and
provides shelter for the passengers on the platform, and forms a shed
for the carriages at night.

Fig. 375 is a sketch of an intermediate or roadside station on a
single line of railway. All the offices, waiting-rooms, etc., are on
one platform, which serves for trains travelling in either direction.
The dotted lines show the additions which would be necessary to make
the station a stopping-place for trains working in opposite
directions.

Fig. 376 shows an ordinary intermediate or roadside station on a
double line of railway, with two passenger platforms, and a connection
between them either by subway or over-line footbridge. The principal
offices and waiting-rooms are shown on the one side, and only small
waiting-rooms, etc., on the other.

[Illustration: Fig. 376]

[Illustration: Fig. 377, 378]

[Illustration: Fig. 379, 380]

[Illustration: Fig. 381, 382]

Fig. 377 is a sketch of a double-line intermediate or roadside station
at the junction of a small single-line branch railway. Branch-line
passengers to and from the main DOWN-line trains merely walk across
the platform to get into their respective trains, and those to or from    258
the main UP trains walk across the footbridge or subway to get to the
opposite platform.

Fig. 378 is a plan of a double-line roadside station, with two
main-line passenger platforms and a dock line and platform for the use
of local or branch-line trains. This arrangement is applicable where
the actual junction with the main line is at a little distance from
the station, but not sufficiently far away to warrant an additional
junction station as shown in Fig. 377.

Fig. 379 shows a similar roadside station laid out with a more
comprehensive arrangement of dock-lines and platforms. The lines
alongside the main passenger platforms are _turn-outs_ from the
main-line proper, and leave the latter free for the passage of fast
through trains or goods trains when an ordinary passenger train is
standing alongside the platform. In this way a fast non-stopping train
can overtake and be sent forward in advance of a slow passenger train.

Fig. 380 shows a roadside station with two double platforms, the inner
lines and platforms being reserved for main-line passenger trains, and
the outer lines for branch-line trains. By this arrangement carriages
can be quickly transferred from a branch-line train to a main-line
train, and _vice versâ_; access from the public road, or from one
platform to the other, can be obtained either by subway or over-line
footbridge.

Fig. 381 is a sketch plan of an island platform for a double-line
roadside station, near which there are junctions with two branch
lines. The UP and DOWN main lines run alongside the wide
portion of the platform, and the branch lines run into the two dock
platforms. The waiting-rooms, refreshment-rooms, etc., are placed in
groups on the wide platform, spaces being left between the blocks for
the convenience of access from side to side. The booking-office and
parcels-office are placed alongside the approach road on the higher
level. An over-line footbridge extends from the booking-hall to the
dock platforms, terminating with steps on one side and an inclined
ramp of 1 in 8 on the other. In carrying out the above plan for a
railway on an embankment, the access from the booking-hall to the
platform would be provided by a subway instead of an over-line
footbridge.

Fig. 382 shows another form of island platform, also arranged for
UP and DOWN main-line trains, and two branch-line trains. The
access is obtained from a public-road over-line bridge crossing the       259
railway, and the booking-office is placed at the top of an incline, or
ramp, leading down to the platform. The dock-line platforms are
arranged different to those in the preceding example, with the object
of providing longer platforms for the main-line trains. This result,
however, is obtained at some little inconvenience to the dock-line
trains, as the passengers from one of these must walk round a portion
of two platforms to get into the other dock-line train, instead of
merely walking across the platform as in Fig. 381.

In some cases of island platforms the total width of the station
buildings and platforms is made much greater than indicated in the
above sketches, and a wide, easy incline constructed from an over-line
public-road bridge, to allow cabs and carriages to come down to a
large paved area between the platforms, for the convenience of setting
down and taking up the train passengers and their luggage.

The island-platform arrangement possesses many advantages for the
exchange of passenger traffic. All the platforms are connected and on
one level, and passengers, together with their luggage, can be quickly
transferred from one train to another. One set of waiting-rooms,
refreshment-rooms, etc., are sufficient, and are available for the
passengers of all the four trains. A smaller number of station men are
required for the work, as the staff can be more concentrated and
better utilized than when there are separate platforms on opposite
sides of the line.

The number, size, and arrangement of waiting-rooms and other offices
for the public at a large station will depend upon the amount and
description of traffic to be dealt with at the particular station
under consideration. Where the passenger traffic is to a large extent
of a local or short distance character, a moderate amount of
waiting-room space may be sufficient, as these local passengers
regulate their arrival so as to avoid waiting any great length of time
for the trains. An enormous suburban passenger traffic is carried on
in many places with a very limited waiting-room accommodation, the
frequency of the trains and the routine of the travellers reducing the
necessity of such rooms to a minimum. A more ample waiting-room space
will be necessary when providing for a large, long journey, or through
traffic, and for stations at seaports, as the intending passengers,
particularly those landing from steamers, generally reach the station
a considerable time before the departure of the trains to take them       260
forward. For this class of traffic it will also be necessary to
provide suitable refreshment-rooms. At large terminal stations it is
frequently found more convenient for the working of the traffic to
have two or more sets of waiting-rooms, etc., separating the local and
long-journey passengers, and placing the rooms alongside the
corresponding platforms.

Lavatories and conveniences at large stations should be provided on a
liberal scale, and fitted up in the most substantial and efficient
manner. Not only should they be thoroughly well ventilated, but they
should have abundance of light. Nothing tends so much to ensure order
and cleanliness in these places as plenty of light.

It will frequently be found that at many of the large important
stations there are local surroundings and circumstances of level and
foundations, which will to a great extent influence the arrangement of
the rooms and offices to be devoted to the public service. No fixed or
standard type could be adopted for all cases. Each one will have to be
studied out to suit the locality, and the grouping must be made to
work in with the best facilities obtainable. In all such cases one of
the principal points is to select a convenient position for the
booking-hall, easy of access to all persons entering the station
premises. On no account should the ticket-office be placed in a
position tending to block the thoroughfare on to the platforms. A
large number of intending passengers may already be in possession of
tickets, and the station arrangements should enable these passengers
to proceed at once to the platforms without having to struggle or
force their way through crowds of other passengers gathered round the
ticket windows. In some instances it is found expedient to provide
auxiliary booking-offices for excursion traffic, to be used only on
special occasions, thus restricting the principal booking-offices to
the ordinary main-line booking.

When laying out small intermediate or roadside stations for either
double or single line, or small terminal stations on short branch
lines in thinly populated districts, it becomes a question how to
provide the requisite statutory accommodation with a minimum amount of
building. The following sketches taken from actual examples may be of
use for reference.

Fig. 383 shows the smallest size of station building that can very
well be constructed to be of any practical service. It comprises an
office for the station-master, who has to attend to the tickets,          261
parcels, and telegraph; a waiting-hall with glazed front; a small
waiting-room and W.C. for ladies; and a yard with conveniences for
gentlemen, coal store, etc. Access to the station is obtained through
a gateway in the platform fencing.

Fig. 384 shows a somewhat similar arrangement, but with two additional
rooms. The road approach to the station is brought alongside and
parallel to the building, and access to the platform is obtained by
passing through the booking-hall, which has a glazed front to the
line.

Fig. 385 gives the particulars of a building containing rather more
accommodation than the two preceding examples.

Fig. 386 shows a small terminal station for a short branch line where
there is a moderate tourist traffic during the season. In addition to
the regular station accommodation, a refreshment-room is added for the
convenience of those passengers who have to drive into the country, or
have arrived at the station by road conveyance. The platform roof,
which is extended out over the line of rails, as shown on the
transverse section, forms a complete covering for the platform, and
serves for a carriage-shed at night.

The above sketches merely illustrate types of some small stations
suitable for home or colonial lines, and may be built of stone, brick,
concrete, iron, or timber. For towns of more importance, the offices
and rooms would have to be increased both in number and size. On
foreign lines it is customary to provide an office and large hall
fitted up with counters for the use of the Local Excise Authorities in
the examination of passengers’ luggage; and at some stations one or
more rooms have to be set apart for the use of the military
authorities.

Narrow platforms should always be avoided, especially in front of the
offices and waiting-rooms. Nothing tends more to check the proper
expeditious working of the traffic than a confined space for the
movement of the passengers and of the station staff carrying luggage.

[Illustration: Fig. 383, 384, 385]

[Illustration: Fig. 386]

In cases where the traffic will warrant the expenditure, it will be
found an advantage to construct a light roof or verandah over a
portion of the platforms of roadside stations. This covering will
provide a convenient shelter for the passengers and their luggage, and
prevent the crowding of booking-halls and doorways during inclement
weather. In hot countries a verandah or awning of some description on
the platforms is an absolute necessity, and those travellers who have     264
had any experience of railways under a tropical sun, will call to mind
the celerity with which the passengers seek such welcome shade.

A very important item in the construction of a large terminal station
is the roof over the lines and platforms. Wrought-iron and steel can
now be obtained in so many convenient sections, and at such moderate
prices, that timber-framed roofs, except for very small spans, are now
rarely used for railway work. The metallic structure is much lighter
in appearance and more durable, besides being less exposed to
destruction by fire. The introduction of iron and steel has enabled
roofs to be constructed of very much larger spans than would have been
prudent to have attempted in timber; at the same time it must be kept
in mind that, notwithstanding this increased facility of construction,
the cost of a roof per relative area covered increases very rapidly as
the span increases. The extent of space to be roofed over in some of
our modern terminal stations is so large that the question of
roof-spans to be adopted has to be considered very carefully. It has
been argued by some that if the area be divided out into small or
moderate spans, the presence of the rows of columns for supporting the
roof might preclude the possibility of any future re-location of the
lines and platforms except by an entire rearrangement of the
roof-work. On the other hand, it may also be stated that railway
engineers have now obtained such a thorough experience of the
necessary relative proportions of platforms and carriage-lines for
large stations, as to enable them to lay out these works without any
risk of requiring alterations for many years.

[Illustration: Fig. 387, 388, 389, 390, 391, 392, 393]

[Illustration: Fig. 394, 395, 396, 397, 398]

[Illustration: Fig. 399, 400, 401, 402]

[Illustration: Fig. 403, 404, 405]

[Illustration: Fig. 406]

[Illustration: Fig. 407, 408, 409, 410]

There are so many descriptions of roof-principals used in railway
stations that it would be impossible here to introduce more than a few
examples. Figs. 387 to 405 illustrate by diagram sketches a series of
types taken from actual practice. Fig. 406 gives more in detail the
particulars of the roof-principal of 60 feet span, Fig. 392. As will
be noted from Fig. 406, the width of 120 feet between the walls is
divided into two spans of 60 feet each, the ends of the principals in
the centre of the 120 feet being carried on arched wrought-iron
girders of 48 feet span, supported on strong ornamental cast-iron
columns placed at 48-foot centres. The rain-water from the large
centre gutter is taken down inside the columns and conveyed away to
drainage pipes laid down for the purpose. The 60-foot principal above
described forms a very strong roof, and is light in cost and              271
maintenance. The weight of ironwork, both wrought and cast, in the
principals, arched wrought-iron girders, cast-iron columns, centre
gutters, etc., is only 0·51 of a ton per square (of 100 square feet)
of area covered. For comparison, the weight of ironwork in the roof,
Fig. 402, of 198 feet span is 1·42 ton per square of area covered; and
of the roof, Fig. 404, of 210 feet span, is 2·07 tons per square.

This increase in weight per square as the spans go on increasing
results, not only in a much larger outlay for original construction,
but entails also a proportionally heavier expenditure for maintenance
and painting. The item of painting alone is an expensive one in all
iron-roof work, and must be attended to regularly for the proper
protection and appearance of the ironwork. With the smaller spans, the
roof-trusses form very convenient supports for painters’ scaffolding
or planking, but with the very large spans the greater height and the
form of the roof-principals render specially designed scaffolding and
appliances necessary for the painting and repairs.

Doubtless there is something very attractive about a large span roof,
its bold outline stretching from side to side of a wide covered area
imparts an imposing effect which cannot be claimed for smaller or more
moderate spans; but where roofs are constructed for purely utilitarian
purposes it becomes a question worthy of grave consideration whether a
series of smaller spans would not provide the same practical benefits
as would be obtained from one very large span. Upon referring to the
typical sketch of a terminal station, Fig. 373, it will be seen that
the total width from inside to inside of main walls is 240 feet. The
lines and platforms are so arranged that by placing rows of columns at
A, A, B, B, and C, C, the entire width may be divided out into four
spans of 60 feet; or, if preferred, a row of columns at B, B may be
adopted, resulting in two spans of 120 feet, or the entire width may
be included in one large span of 240 feet. Any one of the three
arrangements will provide an effectual roof-covering, and the
selection must be decided by the cost or expediency.

Another way to avoid the introduction of large span-roof principals,
and to preserve the covered area free from intervening columns, is to
erect strong truss-girders extending across at right angles from the
main walls. These truss-girders are placed at suitable distances, and     272
carry simple roof-principals of convenient spans. In some cases the
roof-principals are placed as shown in Figs. 407 and 408, and in
others as in Fig. 409.

In another system the roof-principals are incorporated with the main
truss-girders, as in Fig. 410.

With the above type of covering the truss-girders take the place of
the arched wrought-iron girders and cast-iron columns, as illustrated
in Fig. 406, but will be more costly, as may be gathered from the
following brief comparison: Assuming the area to be covered as 480
feet long and 180 feet wide, then the width of 180 feet could be
divided into three spans of 60 feet each, or one centre span of 65
feet, and two of 57 feet 6 inches if they would work in more
conveniently. With columns at 48-foot centres longitudinally, the
three-span arrangement would contain the following:--Twenty cast-iron
columns in the two rows, or twenty-two columns if two columns are
placed side by side at the extreme end; 960 lineal feet of light
arched wrought-iron girders in twenty girders of 48 feet span.

On the other hand, with the truss-girders placed at 40-foot centres to
suit roof-principals resting on the tops of girders, as shown in Fig.
409, or to suit the arrangement shown in Fig. 407, there would be
twelve heavy truss-girders, each of 180 feet span, making a total
length of 2160 lineal feet of deep truss-girder work, exclusive of
about another 60 lineal feet, which would be required for the bearings
on the side walls.

The successful lighting by day of a large roofed-in station will
depend principally upon an appropriate distribution of the glazed
portions. With a large span, and the glass skylights placed near the
apex, the side lines and platforms will be much less efficiently
lighted than those near the centre; and again, if the glazed parts are
only at the sides, then the centre portion will be rather in the
shade. Where possible it is better to place the glazed portions and
slated portions alternately, so as to obtain a more uniform light all
over the centre area, somewhat similar to the arrangement shown in
Fig. 406.

Roofs over passenger platforms at roadside stations are made in many
types, the arrangement depending in a great measure upon the width of
platform to be covered. In many of the earlier stations the roof was
extended across from side to side, and included the lines of rails as
well as the UP and DOWN platforms, a system which was not only
costly, but had the disadvantage that the steam and smoke from passing    273
trains remained for some time under the roof before it was thoroughly
dispersed. The more modern and more economical plan is to put the roof
or shelter over the platforms only, and allow the steam and smoke to
pass away into the air. In designing the latter class of roof, the
fewer supporting columns the better, so as to diminish as far as
possible the obstructions on the platforms. Where the platform is
unavoidably narrow, the roof may be carried on curved brackets
projecting out from the walls.

Except in tropical countries, where shade is more acceptable than
strong light, a liberal amount of glass should be provided in these
platform roofs. On many of our home railways they are entirely covered
with glass, and the abundance of light is found to be of great
assistance in the working of the traffic. Figs. 411 to 420 are
sketches of a few out of the many types of small roofs which have been
erected over single and island platforms.


Goods-sheds.--The form and dimensions of a goods-shed for any
station must be determined by the description and amount of traffic to
be transacted at the particular place. With an estimate of the traffic
before him, the engineer must consider the internal arrangement of
building most suitable for the bulk of the merchandise to be
accommodated. The principal object of the shed is to permit of goods
being transferred under cover from or to railway trucks or carts
without being exposed to the weather, and the transfer will be
expedited if the arrangements are made the most convenient for the
particular class of merchandise presented.

For some commodities it is considered preferable to unload direct from
the railway trucks into carts, or _vice versâ_, and thus have only one
handling of the goods. To comply with this method, the cartway must be
made almost down to the same level as the rails, to allow the carts or
drays to be drawn close up alongside the railway trucks, as shown in
Figs. 427 and 428. This type of shed implies a constant supply of
carts, so as not to detain the railway trucks, or necessitate the
stacking or storing of goods on the low level floor in the way of
carting movements.

[Illustration: Fig. 411, 412, 413, 414]

[Illustration: Fig. 415, 416, 417, 418, 419, 420]

[Illustration: Fig. 421, 422, 423, 424, 425]

[Illustration: Fig. 426, 427, 428, 429]

For general merchandise in boxes or bales, a raised loading-bank
inside the shed is usually found to be the most convenient arrangement
both for loading and unloading. The top of the loading-bank should be
a little below the level of the railway-truck floor to give clearance
to all truck-doors opening outwards. By means of short portable
gangways or landings, the moderate-sized packages are readily             278
transferred to or from the trucks, either by hand or by small
two-wheeled trolleys, the heavier pieces being lifted by cranes. The
cartway should run parallel to the rails on the opposite side of the
loading-bank, and may be either inside or outside the building,
according to the importance of the place. When the cartway is inside,
the entire front of the loading-bank is available for cart traffic,
but this advantage entails a considerable increase in the size and
cost of the building. When the cartway is outside, the cart traffic is
worked through large doorways placed at suitable distances, and fitted
with projecting roofs or awnings to protect the goods during the
loading or unloading. At some of these doorways, short docks about 10
feet square, or more, are formed in the loading-bank, into which the
carts may be set back fairly into the shed for the greater convenience
of the transhipment of the goods by hand or crane power. Where the
stacking space is ample, the contents of several railway trucks may be
discharged on to the loading-bank without any delay in waiting for
carts, and the same railway trucks may be loaded with other goods and
dispatched outwards, or may be taken away empty if the loading-bank is
reserved for arriving goods only. Where the traffic is large and
constant there is an advantage in having separate goods-sheds for the
inwards and outwards work.

The following diagram sketches will illustrate some of the many types
of goods-sheds in use on railways:--

Fig. 421 shows a shed suitable for general merchandise at a small
roadside station. For economy of construction, the line of rails and
cartway are both placed outside the building. A small goods-office is
built at one end, in which is fixed the pedestal and lever indicator
of the cart-weighing machine. The roof is projected outwards over the
doorways for the railway trucks and for carts. The railway truck
doorways are spaced to correspond to the length of the trucks. A
narrow platform, about 3 feet wide, is formed outside the shed
alongside the trucks for the convenience of the men when loading or
unloading.

Fig. 422 represents a rather larger shed, with the line of rails
inside the building and cartway outside. With this type the railway
trucks are entirely under cover, and can be unloaded or loaded more
conveniently. It has also the additional advantage that the trucks and
their contents can be left secure when the shed is locked up at
closing time.

Fig. 423 shows a shed with a line of rails down the centre, and a         279
loading-bank on each side, the cartways being outside the building;
one loading-bank is for inwards goods, and the other for outwards
goods. On the arrival of a loaded railway truck, the door on one side
is opened, and the contents unloaded on to one of the loading-banks.
The door is then closed, and the opposite door opened for loading from
the other loading-bank. By this method a railway truck can be unloaded
and loaded again without changing its position.

Fig. 424 represents a shed with two lines of rails down the centre and
loading-banks on each side, the cartways being outside the building.
One line of rails and corresponding loading-bank is for inwards goods,
and the other line of rails and loading-bank for outwards goods. When
the railway trucks on the arriving line are unloaded, they are either
drawn out of the shed and shunted on to the opposite line to be loaded
again, or transferred direct on to the opposite line by turn-tables,
or traversers, placed at convenient distances between the columns
supporting the roof.

Fig. 425 illustrates a shed in which both the line of rails and
cartway are placed inside the building. This is no doubt the most
convenient type for transfer of general goods, as all the operations
of transhipment are carried on entirely under cover; but it is the
most costly, on account of the large building and roof area required.

Fig. 426 shows a large double shed similar in general arrangement to
the type represented in Fig. 425, but with three lines of rails down
the centre. The line A may be used for inwards goods, and C for
outwards. By means of turn-tables, or traversers, connecting the three
lines at convenient distances in the length of the building, the
unloaded trucks can be transferred on to the far line, C, for
loading again, or on to the line B, to be drawn away out of the
building. The lines A and C may both be used for inwards traffic,
or both for outwards, and the line B used for taking away or
bringing in empty trucks.

Fig. 427 represents a shed with the line of rails and cartway inside the
building, and both very nearly on the same level. This class of shed is
often considered the most suitable for fruit, vegetables, and certain
light goods which require prompt delivery and careful handling.

Fig. 428 shows a form of shed with a raised loading-bank on one side      280
of a line of rails, and a cartway on the other. With this arrangement
the railway trucks may be loaded or unloaded, either from the raised
loading-bank or direct from carts and drays drawn up alongside the
trucks, according to the description of merchandise presented.

Fig. 429 shows a type of umbrella roof sometimes erected over a narrow
loading-bank outside of a goods-shed. It is simple and economical in
construction, and provides good accommodation for loading and
unloading under cover packages and goods of secondary importance.

The above sketches illustrate some of the many arrangements for
goods-sheds, and can be modified and extended in several ways. The
leading dimensions, widths of loading-banks, cartways, and gauge of
lines, will have to be adjusted to suit circumstances.

Looking at a goods-shed merely as a medium for the convenient transfer
of merchandise between the railway and the roadway, the inference is
soon drawn that the removal of the goods into trucks or carts should
be effected as speedily as possible, otherwise a large extent of
shed-room will be required for carrying on a moderate amount of work.
Every effort should be made to clear the goods from the loading-bank
as soon as they have been properly unloaded and checked. Any laxity in
this respect will cause an outcry for increased accommodation, which a
little more energy and careful organization would have prevented.

Timber plank floors are generally preferred for inside loading-banks.
Inside cartways should be formed either of granite setts or
wooden-block paving; the latter is better, being less noisy, and, if
occasionally sprinkled with sand, will afford a good foothold for the
horses. A macadamized roadway under cover is never satisfactory, as it
is always dry, and never binds together into a compact even surface.
Sliding or rolling doors are the best for goods-sheds, as they are
more out of the way, and under better control during high winds.

Cranes of appropriate strengths, and worked by hand or other
motive-power, should be distributed in suitable positions throughout
the shed. They should be placed so that they can, when required, lift
direct out of a railway truck on the one side, and deposit into a cart
or dray on the opposite side of the loading-bank.

Goods-sheds may be built of stone, brick, iron, or timber, or a           281
combination of all of them. Where the requirements are well proved,
and the traffic certain, it is better to build a substantial permanent
structure. Iron sheds, with sides and roofs of galvanized corrugated
iron sheets, will last for many years if not made of too light
materials. There are many cases where it is more prudent to put up a
goods-shed in timber than to incur the cost of one of more permanent
character. Where the traffic is uncertain, or the foundations bad, or
out in undeveloped districts abroad, a building of timber will serve
the purpose for a number of years, or until the period of probation
has passed, and the actual requirements are accurately ascertained. In
a timber-built shed, the decay usually commences about the ground
line, but if the nature of the soil will permit of the construction of
a small dwarf foundation wall of masonry or concrete up to about nine
inches above the ground line, the life of the building will be
prolonged for several years.

The best method of admitting daylight into a goods-shed is from the
roof, and a liberal extent of roof-glazing should be provided for the
full length of the building, and so distributed as to be well over the
loading-banks. In tropical countries the amount of roof light must be
reduced, on account of the great glare from the sunlight.

An ample supply of artificial light will be necessary when working
after dark or during the night. In some instances the goods-sheds in
large and important business centres have one or more upper storys, in
which goods are warehoused pending the owners’ instructions, the goods
being transferred between the loading-banks and upper floors by lifts
or cranes.

A proper supply of weighing machines for carts, drays, railway trucks,
and packages on the loading-banks will be necessary to facilitate the
checking of the goods.

There is always a large proportion of traffic which can be dealt with
outside the goods-sheds, either on loading-banks or cartways alongside
the sidings. Outside loading-banks should be of good width, with
approach roads of easy gradient. In tropical countries a light shed,
open on all sides, is frequently erected over a portion of these
outside banks, to protect the goods and workmen from the heat of the
sun. Fixed cranes or travelling cranes will be required for lifting
the large packages, heavy castings, and logs of timber. Where there is
a large cattle traffic, separate sidings, loading-banks, and approach     282
roads should be set apart for the purpose, with suitable water-troughs
and cleansing appliances. Horses can be unloaded at any loading-bank,
but for the more valuable class of animals and for carriages it is
usual to construct a special horse and carriage dock, as shown in Fig.
430, the carriages being wheeled off the end of the carriage truck, as
indicated in the section. Cartways alongside the sidings are very
convenient for unloading coals, stone, bricks, sand, lime, and many
other materials which have to be passed out of the trucks in small
quantities at a time. To encourage and facilitate traffic at roadside
stations, traders are frequently allowed to stack or store large
supplies of some of the above materials on ground set apart for the
purpose near some convenient siding, the stock being disposed of in
detail to suit the local requirements. Coal-drops are sometimes
adopted where there is a large trade in that commodity. They are
constructed by carrying the line of rails on strong balks of timber or
small girders placed across the top of walled-in coal-yards or divided
areas. The coal is thrown out of the trucks, and falls a depth of 15
or 20 feet into the yard below. In consequence of the height from
rail-level to ground a large tonnage can be piled up, and stored in a
small area, and the unloading of the trucks effected very rapidly,
particularly so where special trucks with opening floors or hinged
bottoms are used for the purpose. In many cases capacious roofed-in
sheds are built for storing coals, lime, cement, grain, or other
materials liable to deterioration from the weather. These sheds are
built alongside a siding; the contents of the trucks are unloaded or
thrown into the sheds through doors spaced to correspond to the
railway-truck doors, and are carted away through doorways on the
opposite side.

It is customary to place _buffer-stops_ of some form at the
termination of dead-end sidings in a station, to bring to a stand such
carriages or waggons as may be approaching with too much speed to be
stopped without the interposition of some substantial barrier.

Figs. 430, 431, 432, and 433 are sketches of some of the many kinds of
buffer-stops, and will explain themselves. In Fig. 430 the buffer-stop
is made of flange rails, and is shown as fitted in a carriage-dock
with wrought-iron plate landing, A, and plate-iron hinged flaps,
B, B. The latter are turned over, and rest on the floor of the
carriage-truck, to form a pathway when taking on or off a vehicle.

[Illustration: Fig. 430, 431, 432, 433]

Fig. 431 shows a buffer-stop made of double-head or bull-head rails;      284
and Fig. 432 is a buffer-stop made of heavy timbers.

Fig. 433 shows a very simple buffer-stop frequently adopted for
sidings where there is not much traffic. It is made of good old
sleepers bound together with old double-head rails, and the interior
filled with earth or clay.

In addition to the buildings alluded to in the foregoing description,
the engineer has to design and construct very many others in
connection with railways. These will include large running-sheds for
stabling working locomotives; sheds for housing carriages; workshops
for building and repairing engines, carriages, and waggons; foundries;
large stores for materials; offices; dwelling-houses; mess-rooms,
etc.; many of them involving questions of difficult foundations, and
nearly all of them requiring special strength and stability to meet
the heavy weights and vibrations to which they are subjected.




  CHAPTER V.                                                              285

  Sorting-sidings--Turn-tables--Traversers--Water-Tanks and
  Water-Columns.


Sorting-sidings.--On many important long main lines it is necessary
to establish special independent sidings for sorting or arranging
waggons of merchandise and minerals. Where there are only two lines of
rails to serve for the UP and DOWN service of a heavy passenger and
goods traffic, it is imperative to restrict those lines as much as
possible to the actual transit of trains, and not to block them by
unnecessary occupation for shunting purposes. A goods train running a
long distance collects waggons from many roadside stations, and at
some of them several waggons will be taken on, to be forwarded to
various and widely distant destinations. The accumulated train
comprises waggons which must be divided out into groups, to be passed
on either to distant sections of the same railway system, or on to
neighbouring lines. To avoid interruption to the train-working, and
the delay of complicated shunting operations at the roadside stations,
the waggons are attached just as they are dicked up, and the work of
sorting is allowed to stand over until the train arrives at the place
assigned for the purpose. A site for sorting-sidings is generally
selected where the ground and gradient are favourable, and where ample
room can be obtained for a large number of short parallel lines, with
space for future extensions. The arrangement that naturally suggests
itself is that of a series of fan-shaped sidings leading out of main
shunting lines, separate from the main-traffic lines. In some cases
the sorting-sidings are laid down with dead-ends, as in Fig. 434, and
in others they are made as through sidings, connecting at both ends
with shunting lines and main-traffic lines, as in Fig. 435. Each of
the sidings is usually made sufficiently long to hold a complete train
of sorted waggons, and the number of them will depend upon the number     287
of sections to be served, and the amount of waggons to be sorted.
Sometimes the sidings are laid with a slight falling gradient leading
away from the main shunting lines, to facilitate the running out of
the waggons into the respective sidings.

[Illustration: Fig. 434, 435]

An arriving goods train is first drawn out of the main-traffic lines
into one of the shunting lines, and then handed over to the staff of
men in charge of the sorting operations, who at once mark the waggons
according to the number or designation of the particular siding into
which they have to be placed. A suitable engine is generally set apart
for this work, and in a very short time the entire train is divided
out by one or more waggons at a time, and distributed into the various
sidings, representing different sections of the line, or groups to be
handed over to neighbouring railways. When one of these sorting-sidings
contains a full complement of waggons, an engine is attached, and the
train despatched to its destination, leaving the siding clear for
another set of waggons. Where the trains to be sorted are very
numerous, two or more shunting-engines may be engaged working at the
same time on distinct sets of shunting lines and sidings. Sometimes it
may be expedient to have one lot of sorting-sidings leading off the UP
line, and another lot leading off the DOWN line, to meet the
requirements of trains coming and going in both directions. With
sidings well laid out, and fitted with ample facilities, a
well-organized staff can carry out a very large amount of work both
expeditiously and economically. There are several of these
sorting-sidings stations in operation, where from one thousand to two
thousand waggons are sorted and marshalled into trains every
twenty-four hours.

The above diagram sketches merely illustrate the general principle of
the sorting-sidings, and may be modified and enlarged in many ways to
suit the traffic requirements and local surroundings.


Turn-tables.--Turn-tables revolving on fixed centres are made of
various sizes according to their use for engines, carriages, or
waggons. The carrying-beams may be made of cast-iron, wrought-iron, or
steel, but the latter material is the most suitable for tables of more
than 20 feet diameter. For small turn-tables, cast-iron beams will
serve very well, for although more liable to fracture, they will not
suffer so much from rust and oxidization as wrought-iron or steel.288

[Illustration: Fig. 436, 437, 438, 439, 440]

Opinions as to the most convenient position and use of turn-tables        289
have undergone a considerable modification during the past twenty or
twenty-five years. Circular and semi-circular running-sheds for
engines, as in Figs. 436 and 437, are not so often adopted now as
formerly. Although compact and accessible in theory, they possess the
one great drawback that when the turn-table in the centre becomes
deranged by wear or accident, none of the engines on the
standing-lines inside the building can be taken out until the
turn-table is again put into working order. A stock of from twenty to
thirty engines might thus be put entirely out of the service for a day
or more. This objection is considered to be of so serious a nature
that running-sheds are now almost always constructed of rectangular
form, of which Fig. 438 is a type.

With this description of shed, the lines of rails are laid down
parallel to one another, and the engine turn-table is placed on a line
separate and distinct from those lines forming connections with the
shed.

Where there is a large goods traffic, an endeavour is generally made
to so lay down the goods-sheds and approach lines and sidings, that
the full complement of waggons may be shunted in or out of the shed at
one operation. This arrangement, which dispenses with turn-tables
altogether, admits of the ready removal of a central or far-end
waggon, without the necessity of taking out so many others in front
one by one over the turn-table. At the same time, there are large
numbers of these waggon turn-tables in use, and there are many cases
where access to side sheds or detached stores can only be obtained by
turn-tables.

A goods-shed and lines laid down with turn-tables, as in Fig. 439,
will always be more tedious and costly to work than one laid down with
direct through lines, as in Fig. 440. Should either of the turn-tables
shown on Fig. 439 get out of order and become incapable of turning,
then the entire side of the shed controlled by that table will be
rendered useless until the defect be remedied.

Engine turn-tables are rarely made with more than one road on the top.
The most modern types generally consist of two strong wrought-iron or
steel-plate girders well braced together and securely attached to a
middle framework which rests on and revolves round a centre-piece
fixed on a solid foundation To the ends of the girders are attached       290
large roller wheels which travel round a solid iron or steel
roller-path laid down along the circumference. These modern
turn-tables are generally worked on the balancing principle, by
bringing the engine and tender to a stand in such a position on the
rails that the greater portion of the weight is thrown on to the
cup-shaped steel centre, so that a small force applied to the long
outrigged hand-levers at the ends is sufficient to turn one of the
heaviest locomotives. Figs. 441 and 442 give sketch plan and section
of one of these steel-plate girder turn-tables, which has few parts,
and very little to get out of order. The end rollers guide the table
when making any portion of a revolution, and carry such part of the
weight as may not be taken up by the centre. A recess is shown in side
wall to facilitate the inspection of end rollers. In the earlier forms
of engine turn-tables, the revolving movement was effected by
attaching to the upper portion of the girders a strong winch, which
acted upon gearing fixed either to the end rollers, or direct on to a
toothed ring forming part of the roller-path. In cases where the
engine turn-table was in constant use, as in connection with a large
running-shed, the winch was sometimes driven by a small steam-engine
to expedite the movement.

The great increase in the lengths and weights of modern locomotives
has necessitated the removal of many of the old small turn-tables, and
replacing them with others of 45 or 50 feet, or more, in diameter.

[Illustration: Fig. 441, 442, 443, 444, 445]

An engine turn-table is a costly item in railway requirements, not
only in the girder-work, but in the large amount of building in the
side walls and centre pier, and an effort is always made to avoid the
outlay unless the table can be placed where it may be of permanent
use. In the construction of foreign railways, and in our colonies,
where the lines are opened in sections as the work goes forward, the
temporary arrangement shown in Fig. 443 is frequently used instead of
an engine turn-table. The sketch will almost explain itself. On the
main line, A, B, C, D, switches are placed at B and C, from which turn
out curved lines, uniting at the switches E. An engine proceeding from
A, and passing round the curve B, E, G, then round curve G, E, C, and
back along main line, D, C, B, A, will be turned round as efficiently
as on a turn-table. The writer has used this arrangement abroad with
great advantage. It involves very little work or expense beyond laying
down the permanent way, and so soon as the temporary terminus of the      292
line has been advanced further ahead, the rails and sleepers can be
lifted and used again elsewhere.

Figs. 444 and 445 give sketch plan and section of a waggon turn-table
which has been largely adopted. The centre should be securely fixed on
a solid foundation of masonry, brickwork, or concrete. The deep outer
cast-iron ring is made in segments, properly fitted and bolted
together, and fastened down to the foundation course. The stop-checks
are cast on to this outer ring. Two roads, at right angles to each
other, are laid on the turn-table, so that waggons to or from the
goods-shed have only to make one quarter turn of the table. The top is
generally covered with either chequered iron plates or timber to give
good foothold for the men and horses which have to pass over in moving
the waggons. If properly balanced, the table is easily turned by men
pushing at the opposite corners of the waggon, or by a horse and
tail-rope, or by hydraulic power through a capstan. In many cases of
bad or soft foundations these small turn-tables are erected on a
strong framework of creosoted timber.

Carriage turn-tables are now very rarely used. With the old short
four-wheeled carriages the moderate-size turn-table was convenient for
transferring an extra carriage to or from a spare carriage-line
alongside the making-up train at a platform, but modern carriages are
now so much longer, some of them twice the length, or more, than
formerly, that nothing less than an engine turn-table would be large
enough for them. Sometimes a carriage traverser is used for this
station work, but much more frequently these long carriages are
shunted on or off the making-up train by simply running them in or out
through the nearest switches and cross-over road.

[Illustration: Fig. 446, 447]

Fig. 446 is a sketch of a carriage-traverser, of length to suit an
ordinary six-wheeled carriage. The length, however, may be extended to
take on a bogie carriage or any other long carriage. The framing is
made of wrought-iron or steel, well braced together. The carrying
wheels, W, W, run upon rails laid at right angles to the
running-line or siding, and the carriage is moved on to or off the
traverser by means of the hinged ramps shown at R, R. A carriage,
once on the traverser, may be moved across one or several lines of
running road, according to the extent of traverser line laid down; and
this appliance is very suitable for large terminal stations and
carriage-repair shops. It will be observed that the operations of the     294
turn-table and the traverser are quite distinct. With the former a
vehicle can be transferred from one line to another, and also turned
completely round; but with the traverser the vehicles are simply moved
in a parallel direction, from one line to another, and when it is
necessary to turn or change a vehicle end for end, as in the case of a
mail-bag-catching apparatus van or a special saloon, then resort must
be had to a turn-table.


Cranes.--A large portion of the merchandise conveyed on railways
must be lifted into or out of the trucks by cranes. The position,
description, and capacity of these will depend upon the materials to
be handled. Large slow-working powerful cranes will be necessary for
raising heavy castings, large logs of timber, or massive blocks of
stone; while the small quick-acting cranes will be more suitable for
dealing with the lighter packages, casks, and bales.

Fig. 447 shows a gantry or overhead crane, used for lifting heavy
weights out of an ordinary road-waggon, carrying them a short
distance, and then depositing them in a railway truck, or _vice
versâ_. Double-flanged rollers, attached to the ends of the platform
C, C, run upon the rails R, R, which are fixed on
the top of the beams B, B, secured to the verticals A, A.
The working length of the gantry is only limited by the number of the
verticals, and this, being the fixed portion of the work, may be
extended out to any distance required. The travelling or carrying
girders of the platform C, C may be made of wrought-iron, steel,
or timber. They must be strongly framed and braced together as a
platform to carry the lifting machinery and weight lifted, and have
convenient gearing for effecting the transverse or side-to-side
movement, as well as a horizontal movement along the line of rails on
top of the verticals. Where the fixed portion of the gantry is of
considerable length, two or more travelling platforms can be used. In
the sketch given above, the entire gantry is shown as made of timber,
but iron or steel can be equally well adopted, and continuous masonry
or brickwork walls may be built to serve as verticals.

[Illustration: Fig. 448, 449, 450]

Fig. 448 is a sketch of a small handy crane for warehouse work; it is
quick in action, and restricted to weights not exceeding twelve
hundredweight. This form of crane may be strengthened to lift still
greater loads, but in doing so the additional size of the parts, and
the corresponding extra labour in working, detract from its efficiency    296
as a quick-acting crane for light weights.

Fig. 449 shows an ordinary fixed three-ton jib crane, a very
convenient size for general station work. The centre pillar is fixed
into a bed of masonry or a solid block of concrete. The jib is of
wrought-iron or steel, those materials being so much more reliable
than timber, and very little more expensive. This crane must be fixed
so that in one direction the jib may command the centre of a railway
truck, while in the other it can conveniently raise the packages to or
from the carts or loading-bank alongside. In the sketch the crane is
shown as placed on the loading-bank, but it may be placed on the same
level as the rails if preferred. Cranes of this type and strength are
frequently found necessary for the inside work of goods-sheds, where
packages of considerable weight have to be handled. A very similar
class of jib-crane is constantly made for lifting weights of five or
ten tons or more, the different parts being made stronger and heavier
to correspond to the weights to be raised.

Fig. 450 shows a five-ton travelling crane. Although more costly, it
has the advantage over a fixed crane that it can be moved about from
place to place. It is mounted on a very strong waggon framework, and
provided with springs and spring buffers. Instead of moving round a
long deep centre, the jib of the travelling-crane is arranged to work
round a bevelled metal roller-path laid down on the platform of the
waggon, and has a heavy counterweight loaded to correspond to its
capacity. Before commencing to lift any weight strong oak blocks or
filling pieces are inserted between the tops of the axle-boxes and the
under side of main beams of waggon, to relieve the springs of the
pressure which would arise from the weight lifted. From the four
corners of the waggon are suspended chains carrying gripping-hooks to
be attached or clipped round the rails. These gripping-hooks, when
firmly secured to the rails, prevent the crane from tilting over, as
the weight of the waggon and also of the rails and sleepers are
brought into play to counteract any tendency to throw the crane off
its proper balance. With the larger size travelling cranes, capable of
lifting ten or fifteen tons or more, outriggers of joist or
I-iron, moving in slides, are run out at right angles on either
side, and can be loaded with bars of iron or other weights to form a
counterpoise.

A medium-sized travelling-crane is a most useful appliance about a        297
railway station; it has a much greater range of utility than a fixed
crane, but it is not always appreciated as it should be. It merely
requires a line of rails laid down parallel to the rails of siding,
and may be placed either on the same level as the siding, or on the
level of the loading-bank. Being laid flush with the roadway, the
rails do not present any obstacle to the passage of carts or movement
of merchandise. As one waggon on the siding is loaded or unloaded, the
crane can be moved along its own line of rails, and be put to work at
another without the necessity of moving or drawing out any of the
railway waggons on the siding. Five, ten, or twenty, or more railway
waggons can be dealt with in this way, according to the length of
crane-line laid down. The crane can also be readily removed to another
part of the station-yard, or to another station along the line. For
stations with an intermittent or spasmodic traffic in heavy timber,
large blocks of stone, or other unwieldy articles, a travelling-crane
is particularly suitable, as it will meet all the wants so far as the
lifting is concerned, and when the rush of traffic is over, it can be
easily transferred to some other sphere of usefulness. The
crane-siding itself is never very costly, as the rails are generally
old rails taken out of the main line, and laid on good second-hand
sleepers. They have little to do, and merely form a track for the
moving crane.

Fig. 451 is a sketch of an ordinary Goliath crane constructed of
timber. The general arrangement and capabilities of this crane are
somewhat similar to those of the gantry shown in Fig. 447. Both of
them are designed to lift heavy weights, and move them sideways into,
or out of, ordinary road waggons, but the methods of application are
different. In the gantry the verticals are permanently fixed, whereas
in the Goliath the verticals and overhead girders are all attached and
braced together, forming a complete framework which is carried by
double flanged rollers running on the lines of rails R, R. The
winches or gearing for lifting the weights, or slinging them sideways,
or for propelling the crane forward on the rails, are attached to the
verticals as shown, and are worked from the ground-level instead of
the overhead platform, as indicated in the gantry. As each Goliath
crane is complete in itself, there is nothing to prevent two or three
of them working at the same time on a long length of crane-line.

[Illustration: Fig. 451, 452]

Fig. 452 shows an ordinary derrick crane, which, on account of the        299
large and varying sweep of the jib, is found very convenient for
certain classes of work. It occupies a considerable amount of room,
and its adoption is therefore limited to situations where space is of
secondary importance.

All the cranes described above are shown as worked by hand-power, but
they may be worked by steam, hydraulic machinery, or electricity.
Manual power will be the most economical where the use of a crane is
only occasional, but it would be too slow and costly where there is
constant heavy work.


Water-tanks.--A supply of good water forms an important item in
railway working, and ample provision must be made at all principal
stations for the requirements of engines and general station purposes.
According to the locality, the water may either be procured from the
main of some established waterworks company, or be pumped from a well,
or forced up from a stream by a ram, or brought down by gravitation in
pipes from a spring or stream at a distance. Water thus obtained is
conducted into tanks placed at a height of 18 or 20 feet, or more,
above the level of the rails, and forms a storage supply from which
deliveries can be made at a fair pressure and in large volume. The
tanks may be made of cast-iron, wrought-iron, or steel, or even of
wood. In the great timber-producing countries abroad, water-tanks,
some of them of large capacity, are very frequently made of wood, the
circular or half-cask form being preferred; but at home, and on
European lines generally, wooden tanks are rarely used except for
temporary purposes. Cast-iron being less liable to deterioration from
rust than wrought-iron or steel, is much used for water-tanks.

[Illustration: Fig. 453, 454, 457, 455, 456, 461, 460, 459, 462, 463,
464, 458]

Figs. 453 to 457 are sketches of a medium-sized cast-iron water-tank,
to hold about 7800 gallons. The size may be varied both in length,
width, and depth, without in any great measure altering the type. The
lower portion, or tank-house, may be of stone, brick, wood, or iron
framework, and may be utilized as a pump-room, store, or lamp-room. In
the sketch given a row of cast-iron girders are placed across the top
of the walls of the tank-house, to carry the tank, the plate-joints of
the latter being made to coincide with the centre lines of the
girders. The lower and upper edges of the tank-plates are shown curved
in section, the former for appearance and facility of cleaning, and
the latter to check the tendency of the water rippling or splashing       301
over the sides when disturbed during high winds. The large pipe, A,
is securely bolted at the bottom of the tank, and forms a shield or
funnel through which the supply pipe, B, passes upwards into the
tank. C is an overflow, or waste pipe, to carry away any surplus
which may find its way into the tank after the water has risen to its
fixed maximum height. All the contact surfaces of the cast-iron
tank-plates must be accurately chipped or planed, and fitted to ensure
water-tight joints. Stay-rods must be placed at frequent intervals,
connecting the vertical or outer plates to the horizontal or floor
plates. When required to hold more than 20,000 gallons, it is better
to make the tank in two parts, by placing a permanent plate partition
across the middle, in reality making two separate tanks, which can be
connected or disconnected at will. The double tank arrangement gives
additional strength, and possesses the advantage that the one tank can
be emptied and cleaned out while the other remains in service.

Water-tanks constructed of wrought-iron or steel plates are usually
made circular in form, with vertical sides. The floor-plates must be
either carried on small girders, as in the cast-iron tank, or be
strengthened internally with angle-irons, tee-irons, and tie-rods. The
rivetting must be well done, all joints sound and watertight. This
class of tank must be kept well painted, or oxidization will take
place very rapidly. The arrangement of inlet, waste-pipe, and delivery
pipe may be the same as for the cast-iron tank. Although frequently
seen abroad, these circular wrought-iron tanks are not often adopted
at home. By many the appearance of the circular tank is considered
inferior to one of neat rectangular shape, and the form of the round
tower does not lend itself so conveniently for use as a pump-room or
store.

There may be no practical difficulty in constructing a large circular
wooden vat or water-tank, but there cannot be any great actual
economy, except in those countries where suitable timber is very
cheap, and iron very dear. The wooden tank must be made of selected
materials, and by skilled workmen; but however carefully constructed
it cannot be expected to last so long as an iron tank. In many parts
of the United States of America there are excellent examples of the
circular wooden tank, strongly put together, and covered with a light
ornamental roof. Numbers of these wooden tanks have been erected there
in places where the cost of carriage alone of an iron tank would have
been a serious item, and where suitable timber was fortunately            302
close at hand.

In cases where engines are watered direct from a water-tank, a simple
delivery-valve, as shown in the sketch (Fig. 458), will answer the
purpose. This valve has to be pulled open by the chain and lever,
D, and when released falls with its own weight, and is kept closed
by the pressure of the water above. The delivery-pipe should not be
less than 7 or 8 inches in diameter, to accelerate the filling of the
tenders. Where water has to be delivered to engines at two or more
places in a station-yard, and the supply derived from the same
principal tank, the result may be obtained either by laying down 7 or
8-inch main pipes from the principal tank to separate water-columns,
or by erecting two or more pedestal water-tanks, similar to Figs. 459
to 462, each of which holds a little more than the average quantity
for one tender, and can be fed from the principal tank by a
comparatively small pipe of 3 or 4 inches in diameter. It is simply a
question of expense--whether it is cheaper to lay down a long length
of 7 or 8-inch main pipe and ordinary water-columns, or to adopt the
small pipes and pedestal tanks.

Figs. 459 to 462 are sketches of a medium-sized pedestal water-tank to
hold 1200 gallons. The supporting column must have a very wide base,
bolted down to a solid foundation. The tank itself, made circular in
plan, is generally constructed of light plates of wrought-iron or
steel, the lower portion or floor of tank being very securely attached
to the vertical column. Notwithstanding their top-heavy appearance,
these pedestal tanks can be made very firm and steady if enough width
be given to the base-plate, and the tank properly fixed to the column.
Water is led into these pedestal tanks by a small pipe passing up
inside the supporting column, and the delivery may be effected by a
simple valve, as explained for Fig. 458.

Fig 463 shows one type of water column for watering engines. The wide
base-plate is bolted down on to a foundation of stonework, brickwork,
or concrete, and the main supply pipe (not less than 7 or 8 inches in
diameter) is carried up inside the column, and connected with the
screw valve, A, which regulates the delivery to the tenders. The
curved top, which forms the outlet, and carries a leather hose, works
on a swivel joint, and can be swung round, either to the right or
left, for convenience of supplying engines on one or two
standing-lines. The delivery valve can be opened or closed by the         303
small hand-wheel B, which is conveniently accessible to the man on
the tender. On the above sketch (Fig. 463) the water column is shown
placed at an ordinary normal distance from the rails; but in cases
where there is considerable space between the two lines of rails, or
where a platform intervenes, the swinging arm may be extended out to
the necessary length, and counterbalanced as shown in Fig. 464.




  CHAPTER VI.                                                             304

  Comparative Weights of some Types of Modern Locomotives.


Weights of Locomotive Engines.--The demand for higher speeds of
passenger trains, with more conveniences, luxuries, and consequent
increased weights in the carriages, has naturally led to greatly
increased power and weight of the locomotives devoted to the passenger
service. Although these engine weights have so largely increased
during the past twenty-five years, there is nothing to indicate that
they have yet reached the maximum. The tendency is still to increase,
and will doubtless continue, so long as the permanent way can be made
to sustain such enormous rolling loads. Locomotives for goods trains
have also increased in power and size, but perhaps not in the same
proportion as those for the passenger service. There is not the same
disposition to expedite the transit of goods and minerals, which do
not deteriorate during a long journey. Perishable articles, such as
fish, fruit, and milk, are usually conveyed by passenger trains, or
trains set apart specially for the purpose.

[Illustration: Fig. 465, 466, 467]

The heavier engine doubtless possesses greater tractive power, but
apart from the question of tractive power is the all-important one of
steadiness and safety on the rails. A locomotive passing round a
curve, even at a moderate velocity, produces disturbances in
proportion to the capability of the machine to adapt itself to the
altered position, and if both the engine and permanent way are
constructed so as to be almost unyielding, then destructive wear and
tear and increased risk of derailment must ensue. The adoption of the
four-wheel bogie truck to the locomotives on our home and continental
lines--although very slow in coming--has contributed greatly to their
improvement, enabling the weight to be distributed over a longer, yet
more flexible wheel-base, affording greater facility and comparative
safety in traversing curves; and rolling, or passing over the rails,      306
with as little injurious effect to them as possible. It is strange to
find that the four-wheel bogie truck, originally designed in England
in the early days of the railway era, should for so long have met with
so little favour on this side of the Atlantic. The Americans, at all
times prompt to recognize any appropriate mechanical arrangement,
adopted the bogie truck upon its first introduction into the States.
They have worked out many improvements in the details, and upon the
thousands of locomotives on their vast network of railways, the bogie
truck, in one form or another, has been universally adopted from the
beginning.

On our home and continental lines, the modern express locomotive, with
a four-wheel bogie truck in front, is a much longer vehicle than its
predecessors, and its total weight is distributed over a greater
wheel-base; but the actual weight placed upon the driving-wheels, or
on the coupled wheels, is now very much in excess of former practice,
and must be taken into consideration when working out the details of
girders and cross-girders of under-line bridges. Numbers of girder
bridges have had to be taken down and replaced with stronger
structures, not for reasons of wear or decay, but simply because they
were incapable of carrying with safety the modern heavy rolling loads.
Present experience points out the expediency of providing in all new
under-line bridges a liberal margin of strength to meet future
developments.

Figs. 465 to 479 are diagram sketches of a few modern types of
locomotives, giving leading dimensions and weights, and may be found
useful for reference when working out the necessary strengths of the
various portions of bridge-work. Upon comparing some of the principal
particulars with those of the earlier class, it will be noted that in
many of the modern types the piston area has been doubled, the
boiler-pressure doubled, and the weight of the engine doubled also.

The engines shown in Figs. 465 and 467 have great weights placed on
the single driving-wheels, and should only be used where there is a
very strong permanent way. With the four-wheel coupled engines, the
weight for adhesion can be distributed between the driving and
trailing wheels.

[Illustration: Fig. 468, 469, 470]

[Illustration: Fig. 471, 472, 473]

Fig. 473 represents a very excellent type of American engine which has
been extensively adopted in the United States for many years. The six
coupled wheels distribute the weight over a fairly long wheel-base,       309
retaining their united weight for adhesion. The four-wheel bogie truck
in front forms a valuable path-finder to the engine, both for passing
round curves or on straight line. This class of engine is very
serviceable for various kinds of traffic, and is particularly suitable
for lines where the rails and fastenings are comparatively light. In
the example shown, the flanges are turned off the centre pair of
coupled wheels; but for lines where the curves are of small radius,
the flanges may be turned off the leading pair of coupled wheels,
instead of the centre pair, to reduce the length of rigid wheel-base.
This type of engine has latterly been introduced on various European
and foreign railways, and recently on the Highland Railway of
Scotland, as shown in Fig. 470. The writer has had engines of this
class under his charge abroad, and found them to be most useful for
heavy passenger and goods-train service. They run very steadily, are
easy on the permanent way, and light in repairs. As they become better
known they will be more appreciated, and will doubtless before long
supersede in many cases the rigid six-wheel-coupled goods engine. The
principal objection of any importance that can be raised against them
is that on many lines the present engine turn-tables are too small for
such long engines; but it would be far more economical in the long run
to enlarge a few turn-tables than to continue the adoption of rigid
engines which from their form and arrangement tend to unnecessary wear
to themselves and the permanent way.

[Illustration: Fig. 474, 475, 476]

[Illustration: Fig. 477, 478, 479]

Fig. 476 shows an average sample of the ordinary six-wheel-coupled
goods engine in use on so many of our home railways. Where the curves
are easy and the permanent way strong, the drawback of the long rigid
wheel-base may not be so apparent; but for a line abounding in sharp
curves, perhaps no more destructive machine could possibly be devised
than the ordinary six-wheel-coupled goods engine. Without any
flexibility, forced along with great power, and too often driven at
unnecessary high speeds, engines of this type have too small a margin
of safety when traversing the curved portions of the road. A slight
unevenness in the rails, or a sharp flange on the wheel may supply all
that is wanting to cause the engine to leave the track, and the
probability that such risks are more common than is supposed, is far
from satisfactory. The great weight of the engine doubtless tends to
keep it on the track, but the rapid wear of the tyres, and of the         312
inside of the rail-heads clearly demonstrate the enormous amount of
friction and abrasion that takes place.

Fig. 477 represents a type of eight-wheel-coupled engine designed for
hauling passenger or goods trains over long lengths of heavy mountain
inclines. The engine is a large one in every way, and of great total
weight, but the weight is distributed over a long wheel-base and
without imposing a greater tonnage per pair of wheels than is done in
some of the smaller and less powerful engines. The flanges are turned
off the leading pair and third pair of coupled wheels reducing the
rigid wheel-base for curves to 9 feet 8 inches. The four-wheel bogie
truck in front carries only a moderate weight, being so close to the
coupled wheels. Engines of this description require a strong permanent
way, as there is a total weight of 60 tons on the four pairs of
coupled wheels standing on a wheel-base of 15 feet 6 inches.

Figs. 478 and 479 are types of tank-engines in use on some of the
narrow-gauge (3 feet) railways. In general design they are somewhat
similar to the modern class of engine on main lines of 4 feet 8½
inches gauge, with four-wheel bogie truck in front, and four wheels or
six wheels coupled, but with all the parts and weights smaller, to
suit the narrow gauge and lighter permanent way.

The extended use of the bogie truck is an admission of its advantage
over the fixed-wheel arrangement, both for distribution of weight and
facility in passing round curves; but although it is now so largely
adopted for engines and carriages on our home and continental
railways, it is somewhat of an anomaly to find it so very rarely used
for tenders. In the United States all the locomotive tenders--and many
of them of very large size and weight--are carried on two four-wheel
bogie trucks, and traverse the curves as easily as the engines. On
this side of the Atlantic, the prevailing custom is to mount the
tender on six rigid wheels; and as many of these tenders weigh as much
as from 35 to 40 tons in working order, and have a rigid wheel-base of
15 feet, it will be seen at a glance that much unnecessary friction
and wear and tear would be avoided by substituting two four-wheel
bogie trucks for the fixed wheels.




  CHAPTER VII.                                                            313

  Signals--Interlocking--Block Telegraph and Electric Train
  Staff Instruments.


Signals.--Railway tradition alleges that on one of the early lines
opened for passenger traffic, the precautions for public safety were
considered to have been fulfilled by providing a man on horseback to
ride along the track between the rails in the front of the locomotive
engine, to give warning to persons strolling on the line, and to check
the advance of the train when necessary. A very short experience of
this method of working proved that the full capabilities of the
locomotive could not be obtained from a restricted speed of seven or
eight miles an hour, and a more comprehensive system of signalling had
to be devised. By fencing in on both sides of the line, the public
were prevented from making a general highway or promenade along the
railway, and the problem was reduced therefore to the signalling for
the trains alone.

Flags of different colours, held by flagmen stationed at suitable
places, answered the purpose for a while, or so long as the authorized
running speed did not prevent the train being brought to a stand after
sighting a flag warning the engine-driver to stop. As speeds were
increased, a longer or more distant view of signals became imperative,
and tall posts, or semaphore signals, were introduced. Well-defined
blades or discs placed on high posts were easily worked from the
ground-level, and could be seen for long distances, thus enabling the
trains to be controlled or brought to a stand before reaching the
signal. The efficiency of the principle once recognized, improvements
and additions were made from time to time, until we have the simple
acting tall semaphore signal so universally in use at the present
time. The position of the signal arms or blades in the daylight, and
the colours shown by the lamps at night, form the code of signals for
the proper working of the train service; and as the signal arms and
lamps are both worked simultaneously by the same gearing, it is only      314
necessary to light the lamps to put the signals in complete condition
for night-working. For some years, when the traffic was small, with
trains at low speeds and at considerable intervals, one double-arm
semaphore signal-post at a station was made to serve for all purposes;
but as the train service became more frequent and more rapid, it was
found that another semaphore or tall post signal, was necessary to
give warning to the engine-driver some distance back before reaching
the station or _home signal_. More particularly was this necessary at
those stations where it was not intended that every train should stop.
This new signal, called the _distant signal_, very soon came into
general use. It was placed at distances varying from 400 to 800 yards
away back from the station or home signal, and was worked by a long
strained wire extending from the distant signal to a ground-lever
placed near the home signal, the levers for these distant signals and
home signals being thus near together and under the control of one
man. More recently it was found necessary to introduce another
important wire-worked signal called a _starting signal_, which is
placed at the outgoing or departure end of the passenger platforms,
lines, or station sidings, to prevent any train or engine starting or
proceeding on its journey until such starting signal is lowered to
indicate that the line is clear.

These simple, independent, hand-worked semaphore signals did good
service for many years, but being independent and in no way physically
connected with one another at junctions, or stations, or with the
switches they were intended to control, it was quite possible for
mistakes to arise where everything depended upon the accuracy and
prompt decision of the signalman. The possibility that such mistakes
could occur, and the certainty that they actually did occur, and too
often with most disastrous results, led gradually to the grouping and
interlocking of a large number of signal levers and switch levers
together in one signal cabin. The advantages of the concentrating and
interlocking of signals and switches are twofold. In the first place,
one man in the signal cabin can work and control the levers for a
large number of switches and signals, where formerly several men were
required to be located at various places in the station-yard; but the
second, and by far the most important advantage, is that with proper
interlocking arrangements it is practically impossible to give
conflicting signals.

With a modern interlocking frame, and assuming the normal position of     315
all the signals to be at _danger_, then before a signal can be
lowered for an approaching engine or train all the switches and
corresponding signals, from any lines or sidings connecting with the
line to be signalled _clear_ must first be set so as to prevent
any engine or train coming out of such connecting lines or switches on
to the line to be made clear. In a similar manner, before the points
and signals can be set to permit an engine or train to pass from a
siding on to the main line all the necessary signals must first be set
to _danger_ to prevent the approach in either direction of any
engine or train on the main line about to be occupied. The mechanical
arrangements of the interlocking frame are so exact and complete as to
effectually prevent any but the proper combination being made. An
untrained or inexperienced signalman might inadvertently attempt to
pull over a wrong lever, only to find it securely locked and immovable
under the control of other levers. The proper sequence of levers must
be made, and the accurately adjusted mechanism automatically prevents
mistakes which formerly occurred with the old hand-worked signals from
the oversight or confusion of the signalman.

The interlocked switches or points are worked from the signal-cabin by
light wrought-iron tubing (termed rodding) or channel-shaped iron bars
supported on fixed iron rollers, and the signals by galvanized wires
running over light pulleys. Modern signals are always weighted at the
signal-post, so that in the event of the breaking of the pulling-wire
they will fly back to their normal position of danger.

The facility and precision secured by the interlocking machinery
enabled other valuable accessories to be introduced for the more
complete signalling and protection of train-working. Amongst these may
be mentioned the facing-point bolt-lock and rocking-bar,
signal-detectors at points, and throw-off or trap points.

With the old-fashioned hand-worked switches the man standing alongside
could see whether the sliding-rails were properly closed, and also
when the last vehicle of the train had passed over them; but when
important main-line-facing switches or points are worked by rodding
from a signal-cabin some distance away, it is necessary to have some
reliable means to ensure that the sliding-rails are actually brought
close home, and also to prevent the switches being moved again until      316
the entire train has passed over them. A set of switches may be
carefully made and work well, but it is quite possible for some
fracture or obstruction, to intervene and prevent them closing
properly. If a train or engine were passing through them in a trailing
direction, as indicated in Fig. 345, the wheels would most probably
force the sliding-rail home, and no disturbance would arise. If,
however, the train were coming in the opposite or facing direction,
the chances are that some of the wheels would take one road and some
the other, and cause a derailment. The same casualty would occur if
the switches were moved during the passage of the train.

To guard against the above contingencies, the facing-point bolt-lock
and rocking-bar have been introduced. The system is applied in various
forms, but the arrangement shown in Fig. 480 will explain the
principle generally.

A strong casting, A, is securely bolted to the top of the sleeper
carrying the chairs on which rest the point ends of the sliding-rails.
This casting has an internal groove or chamber formed for its entire
length from C to D, as indicated by the dotted lines, and in which
slides the locking-bolt B. The point ends of the switch or
sliding-rails are connected by the transverse rod E, which is forged
into a vertical bar form for that portion of its length, which passes
through the opening, F, prepared for it in the casting A. In this
vertical bar a hole or slot is cut to correspond to the exact size of
the locking-bolt B, and at a distance to suit the sliding-rails when
pulled over to their properly closed position. This locking-bolt, B,
will not pass through the hole in the vertical bar until the
sliding-rails are quite close home, and when once through the hole the
sliding-rails cannot be moved until the locking-bar is withdrawn. In
some cases two holes or slots are cut in the vertical bar to enable
the points to be bolt-locked for both directions.

The rocking-bar is designed to prevent the withdrawal of the
locking-bolt before all the vehicles have passed over the points.

[Illustration: Fig. 480, 483, 481, 482]

This rocking-bar consists of an angle iron or tee-iron bar of a length
equal to the longest wheel-base of the rolling-stock, and is carried
on short pivoted arms working in cast-iron or wrought-iron brackets
secured to the rails as shown in Fig. 481. The pivoted arms have a
movement backward or forward, and when at either the one or the other
extremity, the upper surface of the rocking-bar is sufficiently below     318
the top of the rail to be well clear of the flange of any passing
wheel; but while changing from the one to the other position, and when
the pivoted arms are vertical, or at half-stroke, the upper surface of
the rocking-bar is about level with the top of the rail, and right in
the pathway of the wheel-flange. It is evident, therefore, that when
the pivoted arms are set in the forward or backward position, and one
of the wheels of a train or vehicle has passed on to the rail over the
rocking-bar, the latter cannot be changed or raised and pulled over to
the opposite extremity so long as any one of the wheels of the train
or vehicles remain over the rocking-bar.

As the same ground-crank which pulls over the pivoted arms from
backward to forward also withdraws the locking-bolt B, the latter is
thus held securely in the hole or slot of the transverse rod, E,
until all the wheels of the train have passed off the rocking-bar. The
operation of changing the points from one road to another is very
simple. By means of the rodding G, worked by a lever in the
signal-cabin, the locking-bolt B is first withdrawn from the slot;
the points are then pulled over into the reverse position by the
rodding H, and the locking-bolt B is again set back into one of
the slots by the rodding G. Sometimes, for economy, the points,
bolt-lock, and rocking-bar, are all three worked by one lever in the
signal-cabin, and one set of rodding on the ground, as shown in Fig.
482; but the arrangement is neither so perfect nor so secure as that
shown in Fig. 480. Where there are two sets of rodding and gearing,
the failure or breaking of either of them prevents the complete
combination being made, and indicates at once to the signalman that
something is wrong; but when there is only one set of rodding a
breakage may occur without giving any tangible evidence to the
signalman of the defect, and he may proceed to pull over his signal
lever in ignorance that the points have not been properly made and
bolted. To avoid an accident taking place from the failure of either
rodding or gearing, the signal-detector has been devised, so as to
prevent the possibility of pulling over the signal wire until the
points and locking-bar are both in their proper positions.

The signal-detector is applied in several forms; the one shown in
Figs. 480 and 483 will explain the principle on which its efficacy
depends. A transverse rod, I, attached to the sliding-rail, extends       319
out beyond the rails, and is formed into a flat bar or plate, J,
sliding through the guide-holes K, K in the casting L. Short
upright levers, M and N, work on trunnions fixed in the casting,
and to M and N are attached the wires leading from the
signal-cabin and continuing on to the signal-posts, as shown in
elevation in Fig. 483. Two slots are cut in the plate J to receive
the curved arms of the levers M and N when they are drawn
downwards to pull off the corresponding signals. Neither of the
levers, M or N, can be drawn over unless there is a slot
immediately under the curved arm into which it can enter. When there
is solid plate under a curved arm, the short lever cannot be pulled
over, and the signal therefore remains at danger. The slots in the
plate J are spaced so that one will be brought into position for one
of the curved arms, when the points are close home for the main line,
and the other slot for the other curved arm, when the points are set
for the branch line or siding. The two slots cannot be under the two
curved arms at one and the same time, as one of the signals
corresponds to the main line and the other to the branch line or
siding.

In some forms of signal-detector the transverse rod I is joined on
to a vertical bar which slides through guide-holes in a casting
something similar to the arrangement shown in the casting L.
Longitudinal guide-holes, parallel to the line of rails, are made in
the casting a little above the transverse rod-bar, and through the
longitudinal guide-holes slide two vertical bars which are attached
to, and form part of, the wire connections to the two signals. The
wire bars have each a small tongue or rectangular fin forged on to the
under side of the bar, and there is one corresponding channel cut in
the transverse rod-bar. When the switches are properly closed in one
position, the channel cut of transverse bar will be opposite one of
the wire bar fins, and will allow one of the signals to be pulled over,
but the other wire bar cannot be moved. The closing of the switches in
the reverse position moves the channel cut so as to allow the other
wire bar to be pulled through, but as there is only one channel cut in
the transverse bar, only one signal can be pulled over for each
position of the switches.

[Illustration: Fig. 484, 485, 486, 490, 491, 487, 492, 488, 493, 496,
489, 494, 495, 497]

Throw-off or _trap points_, are introduced to throw an engine or train
off the rails of a siding on to the ballast, and so avoid a collision
with any other train which may be standing or passing on the line of
rails with which such siding forms a connection. Fig. 484 is a diagram    321
sketch of the arrangement, in which the main-line points are indicated
by the letter A, and the trap points by the letter B; one series of
rodding actuated by one lever in the signal-cabin works both the
main-line points and the trap points at the same time and by the same
movement. The connections are so made that when the points A are set
for the passage of trains on the main line, the trap points B are set
open to throw off on to the ballast, as shown in Fig. 484; and when
the main-line points A are set to allow a train to pass from the
siding on to the main line, the trap points B are closed, as shown on
Fig. 485. A disc or other signal, worked or interlocked with the
points, is placed near B to notify the engine-driver when he may pass
out of the siding on to the main line; but should he from any cause
proceed before the points are properly set and the corresponding
signal given, his engine would run off at the ends of the rails C, C,
and be derailed on to the ballast. The inconvenience caused by such
derailment would be trifling compared with what might result from a
collision with a train standing or passing on the main line. In some
cases the siding is continued onwards for a considerable distance from
the trap-point rails C, C, as indicated by the dotted lines D D, and
terminates with a dead end. When this arrangement can be adopted,
derailment is obviated, and the engine is brought to a stand by a
buffer-stop at the end of siding. On no account should trap points be
placed close to the top edge of a high embankment, or up to the
abutment or wing walls of an under-line bridge, where an engine
running through them accidentally might fall down a considerable
height, and cause serious results. All sidings joining on to main
lines should be trapped as above described, and when properly
signalled and interlocked in the signal-cabin, the traffic-working can
be carried on with increased facility and security.

Fig. 486 is a sketch of an average sample of an ordinary single-arm
wooden signal-post, with signal-arm, lamp, spectacles, ladder, and
gearing complete for wire connection to signal-cabin. When the arm
stands out in the horizontal position, representing the _danger_ or
stop signal, the red spectacles will be in front of the lamps, and
will show a red light to an approaching train. When the arm is
lowered, as indicated by the dotted lines, the second spectacle will
be in front of the lamps, and will show either a white or green light
(according to the accepted code) as an _all-right_ signal for the         322
train to proceed. For many years a white light was adopted for the
all-right signal, but latterly, to prevent confusion with other white
lights about a station, there has been an increasing disposition to
use a green light as an all-right signal. Several railway companies
have already effected the change, and others have arranged to follow
their example. The counter-weight W keeps the signal-arm to the
danger position, except when it is raised by the pulling over of the
signal-wire from the signal-cabin working over the pulley P. Should
the wire break when being pulled, the weight W falls down to the
stop-plate, and the signal-arm rises to danger. The signal-posts may
be of wood, wrought-iron, steel lattice-work, or cast-iron.

The arms of _distant signals_ should be cut to a fish-tail shape, as
in Fig. 487, to distinguish them from other signals. Goods-line
signals should have a thin sheet-iron ring, as in Fig. 488. Sometimes
purple glass is used instead of red glass for the spectacles of goods
signals. Letters or numbers may be attached to signal-arms to signify
the lines or sidings to which they correspond. Special signals are
sometimes made with the arm working on a centre pin, as in Fig. 489.

At junctions or places where two or three signals have to be fixed
near together, it is customary to carry them on a bracket signal-post,
as in Figs. 490 and 491. The former represents the home signals at an
ordinary junction, the taller signal being for the main line and the
lower one for the branch line. Fig. 491 shows the home signals at a
junction where there is one line turning out of the main line to the
left and another to the right. The taller signal in this case also
serves for the main line and the two lower signals for the branch
lines.

In important station-yards, where there are a large number of lines
and sidings running side by side, it is not always convenient or
possible to place the respective signal-posts in suitable positions
between the lines. To overcome the difficulty, the signals are erected
on light overhead lattice girders, as shown in Fig. 492. In some
cases, for want of a better position, or to obtain a more
comprehensive view of the lines and signals, the signal-cabin is built
on lattice girders, as in Fig. 493.

Ground or _disc signals_ are fixed at the ground-level, and are worked
in conjunction with trap points or outlet switches from sidings. In
some cases they are worked direct by a connecting-rod from the            323
switches, and serve merely as indicators to show whether the switches
are lying for or against an engine passing out of the siding. In other
cases they are worked independently from the signal-cabin by a
separate lever and wire connection, the interlocking being so arranged
that the lever working the switches must be pulled over before the
lever working the disc signal can be moved. In one type the disc
signal is fixed to a short vertical axis, as shown in Fig. 494, and by
means of a cranked arm is made to rotate a quarter of a circle, so as
to exhibit either a stop or advance signal according to the position
in which the switches are lying. In another type, the lamp is fixed,
and the red disc, with a red glass in the centre, is made to assume a
horizontal or vertical position by a rod and crank, as shown in Fig.
495.

A simple arrangement of rodding and rollers for switch connections is
shown in Fig. 496, the number of sets of rodding being determined by
the number of connections to be made. Fig. 497 is a rodding
compensator, to compensate or adjust for the difference in length of
the rodding arising from variations in the temperature. The
compensator may be used either vertically or horizontally, according
to space or circumstances.

Strong wrought-iron or steel cranks of different angles will be
required when changing the direction of the rodding, or connecting to
switches and facing point-locks. They must be firmly secured to strong
timber framework well bedded in the ballast. For cranks working
switches and bolt-locks, it is better to use extra long timbers under
the rails instead of the ordinary sleepers. Cross-pieces can be bolted
to the ends of the long timbers, and the cranks placed practically on
the same timbers carrying the permanent way. By this means the rails
and cranks can always be maintained in their proper relative positions
as to distance, line, and level.

Without a large series of diagrams it would be impossible to
adequately describe the extent of signalling and interlocking required
at large terminal stations and important roadside stations, but one or
two simple examples may serve to illustrate the general principles.

[Illustration: Fig. 498, 499]

Fig. 498 represents the modern grouping of signals considered
necessary at an ordinary double-line junction, showing all the signals
at their normal or _danger_ position. The numbers marked on each
indicate the numbers of the levers in the interlocking frame of the       325
signal-cabin. Four distinct sets of trains have to be dealt with at
this class of junction, and the interlocking must be so arranged that
when the signals are lowered for the advance of any one train, no
conflicting signals can be given to any other train.

Assuming a train approaching from A, which has to continue on the main
line past B on towards C, then the levers in the signal-cabin must
first be pulled over to set the points 9 and bolt-lock 8 in proper
position for the main line; and this operation will release the levers
which have to be pulled over to lower the signals 5, 4, and 6, but at
the same time will lock, and prevent the pulling over of the levers or
lowering of the signals 2 and 1 for a train from A to B and D, or of
the signals 14 and 15 for a train from D to B and A. The levers will,
however, be free to pull over for setting the points 12 and lowering
the signals 16, 17, and 13 for a train on the main line from C to B
and A.

In a similar manner, assuming a train approaching from D, which has to
continue up to the main line at B and on towards A, then the lever in
the cabin must first be pulled over to set the trailing points 12 in
proper position; and this operation will release the levers which have
to be pulled over to lower the signals 14 and 15, but at the same time
will lock, and prevent the pulling over of the levers or lowering of
the signals 5 and 4 for a train from A to B and C, or of the signals
16 and 17 for a train from C to B and A. The levers will, however, be
free to pull over for setting the points 9 and bolt-lock 8 and
lowering the signals 2 and 1 for the passage of a train on to the
branch line from A to B and D.

For a train from C to B and A, the levers 12, 16, 17, and 13 would be
required, and these would lock levers 14 and 15, and prevent the
approach of any train from D to B, but they would leave free the
levers necessary either for a train from A to B and C, or for a train
from A to B and D, but only one of them at a time, the setting of the
one series locking the other series.

A train from A to B and D would require the proper setting of the
points 9, bolt-lock 8, and signals 2, 1, and 3; and these would lock 5
and 4, but would leave free the levers necessary either for a train
from C to B and A, or for a train from D to B and A, but only one of
them at a time.

The cross-over road from the UP to DOWN main line, near the letter B      326
on sketch, is only intended for use in case of break-down or
accidents, and the normal position of the points is to lie clear for
the passage of trains on the main lines. To use the cross-over road,
the whole of the signals must first be set to _danger_ before the
points 7 and 7 can be opened to permit the passage of an engine or
train from the one main line to the other.

The starting signals 6 and 3 should be placed sufficiently far away
that the longest passenger or goods train may stand between them and
the clearance points at G and E. These starting signals are of great
service to train-working at junctions. Supposing a main-line train
from A arriving at B before the section from B to C was clear, such
train could be brought to a stand at signal 6, and remain there while
another train from A was allowed to pass B, and proceed onwards
towards D; or a branch-line train from A to D could be brought to a
stand at 3, to allow a main-line train to proceed onwards from A to B
and C. The starting signal 13 should be placed well in advance of the
cross-over road to control anything passing from one line to the
other.

Fig. 499 shows the modern grouping of signals for an ordinary
single-line junction. The arrangement is almost practically the same
as for the double-line junction shown in Fig. 498, there being the
same four distinct sets of trains to be controlled, but not any
cross-over road. The signal-cabin is placed on the main line, a little
in advance of the facing points, and a well-fenced-in gangway, the
same height as the engine footplate, is carried out the proper
distance from the rails, on which the signalman can stand to hand over
or receive the train staff from the engine-driver when passing.

At stations and places where there are several sidings and lines
connecting with the main lines, at considerable distances apart, it
will be necessary to have two or more signal-cabins placed in suitable
positions, not only for expediting the working of the constant
shunting movements, but also to insure that there is a signal-cabin
within the regulation distance of all facing points on the main line.
So far as the main line is concerned, the interlocking of these cabins
must be connected, the one with the other, by slotting, or co-acting
gearing, in such manner that the cabin in advance shall always be able
to control the cabin in the rear in the lowering of the main-line
signals for an approaching train. Fig. 376 is a diagram sketch of a       327
typical double-line roadside station with two signal-cabins. The NORTH
cabin has to work the signals and points in connection with the
goods-shed, goods-sidings, and market branch, and the SOUTH cabin,
those in connection with the coal and cattle sidings; and each of the
cabins to work the signals and points of that portion of the main line
adjoining its own cabin. For siding working, each cabin is quite
distinct and independent of the other, but for main-line working the
lowering of the signals can only be effected by the joint operation or
co-acting of both cabins.

Assuming a train approaching from A to proceed in the direction
towards B, then, before the signalman in the NORTH cabin can lower the
UP home-signal C, the signalman in the SOUTH cabin must first pull
over his lever and release the slot which retains the signal C at
_danger_, and in doing so the levers in his own cabin will stand
locked, and prevent the lowering of the signal D, or opening of points
E to allow access from the sidings to UP main line. The cross-over
road F G will also be locked for main line clear. When the slot has
been released from signal C, the signalman in NORTH cabin can lower
the UP home signal C, but before he can pull over the lever for this
purpose he must first lock the points H, to prevent access from the
sidings to the UP main line, and also the points K L of the cross-over
road, to keep the main line clear. A similar operation has to be gone
through for a train approaching from B to proceed in the direction
towards A, when the signalman in NORTH cabin must first withdraw the
slot from the DOWN home-signal M before the signalman in the SOUTH
cabin can lower that signal. A small automatic disc is placed in the
cabin to indicate to the signalman when the slot has been withdrawn by
his colleague in the neighbouring cabin, and for facility of working,
the two cabins are usually placed in communication with each other by
telegraph or telephone.

At some stations similar to the above, where there is a very frequent
train service, with several of the trains running through without
stopping, it is the practice to have a second or lower arm to the home
signals C and M, as shown on the diagram, these lower arms being only
_pulled off_ for through or non-stopping trains, as an indication to
the engine-driver that the line is clear in the section ahead.

In addition to the leading signals shown in the sketches, there           328
are shunting signals for the movement and marshalling of
trains--setting-back signals in connection with the making up of
passenger trains; taking on or off passenger carriages; or moving out
empty passenger carriages; and many other special signals which become
necessary for the working of a large and complicated train service.

The above simple diagrams will explain some of the principal
requirements to be kept in view when working out signalling
arrangements. Where the lines and sidings are very numerous, as at
important junctions and large terminal stations, the signalling
becomes very intricate, and may require three or four cabins, slotted
together in such manner that the necessary co-acting may be insured
for the proper controlling of the mainline signals. Many of these
signal-cabins contain a large number of levers, some of them having as
many as a hundred, and a few of them two hundred and forty levers, or
more, all of them so carefully arranged that no conflicting signal can
be given. Not only has much skill to be exercised in the accurate
adjustment of the interlocking machinery, but much study must be
devoted to determine the exact duty of every lever, for the locking or
releasing of other levers.

Signal-cabins may be built of stone, brick, or wood. They should be
roomy, well ventilated, and have abundance of light. Every
signal-cabin should be placed in the position from which the signalman
can obtain the best view of the signals and points under his charge.
The height of the cabin floor will depend upon any obstacles that may
intervene between the cabin and the signals, such as over-line
bridges, station roofs, buildings, or other obstructions. Sometimes
the floor has to be kept as low as five feet above rail-level, to
secure a line of sight under the over-line bridges; and in others the
floor has to be raised twenty, or even thirty feet above rail-level.

[Illustration: Fig. 500, 508, 501, 502, 506, 507]

Figs. 500, 501, and 502 show plan, transverse section, and elevation
of a signal-cabin suitable for a small roadside station. The lower
story and chimney-stack are of brick, and the upper story of wood,
with slated roof. There is room for an interlocking frame of twenty or
twenty-five levers, and space at the end of the cabin for the
block-telegraph instruments, or electric train-staff instruments. The
roof-work is open up to the slateboards, to obtain as much air
capacity as possible. In the transverse section a winch for working
mechanical gates is shown at the end of the interlocking frame. There     330
is a liberal amount of glass, and two or three sliding windows, which
the signalman can open to enable him to speak to the engine-drivers or
others during shunting operations. The lower story of the cabin can be
utilized for trimming lamps and keeping a small supply of coals and
other stores. When working after dark the lamps in the cabins should
be well protected by shades, to prevent the lights being seen by
engine-drivers, and mistaken for signals.


Interlocking.--There are several systems of interlocking, each of them
varying considerably in the form and mode of application, but all of
them having the same general object of securing or releasing the
necessary levers for each combination of signalling movements. A brief
description of one of the systems will explain the order in which the
movements have to be made, and the security which can be obtained by
the locking.

Figs. 503, 504, and 505, are sketches illustrating one of the types of
wedge and tappet interlocking. Each lever works on a fulcrum or pinion
as at A, and has a lower arm B for lifting the rods leading off to
points or signals, and an arm C to carry a counterweight when necessary.
Cast-iron braces D are placed at convenient distances between the series
of levers to carry the top frame E on which the lever floor casing
F is bolted. This casing is continuous from end to end of the locking
frame, with the exception of the narrow openings through which the
levers travel when moving backwards or forwards. The sleeve-block
G, resting in the depressed portions of the arc, retains the lever in
position. When taking hold of the main lever L, the signalman’s hand
draws the small side lever M, close to the main lever, and raises the
sleeve-block G sufficiently high to pass over the top of arc F, the
lever L can then be pulled or pushed over, and the block G will fall
into the depression at the end of the stroke when the hand is removed.
N is a tappet or thin flat bar attached to the main lever, and which
works backwards or forwards between the wedges in the wedge frame O.
The wedges move horizontally between guide pieces, and work either
singly or are connected by the lower slide bars to other wedges some
distance away on the frame according to the position of the levers
which have to stand or move in unison for the releasing or locking. A
strong cover is placed over the wedge frame to keep out the dirt.

[Illustration: Fig. 503, 504, 505]

Figs. 504 and 505 show plan views of four levers in a signal cabin        332
taken just above the level of the tappets. In Fig. 504, all the levers
are in their _normal_ or forward position, with the home and distant
signals at _danger_, and the facing points leading into loop or siding
lying for main line. Previous to the approach of a train on the main
line, the home and distant signals have to be lowered, and will
require the pulling over of levers 1 and 2; but these levers cannot of
themselves be moved, as the wedges P and Q are locked by the straight side
of lever 3. The operation would therefore be as follows:--points lever
4 being set in its normal position for the main line would remain
forward, lever 3 working the facing point bolt-lock would be pulled
over, and in doing so would move the wedge R to the right into the
recess of tappet of lever 4, locking that lever, and presenting the
recess of its own tappet ready to receive the wedge Q. Lever 2 can
then be pulled over, and will move the wedge Q to the right into the
recess of tappet of lever 3, and present its own recess for wedge P.
The pulling over of lever 1 completes the series, by moving the wedge
P over to the right into the recess of tappet of lever 2. Fig. 505
shows the positions of the tappets and wedges with the levers 1, 2,
and 3, pulled over to make the combination described. Upon
examination, it will be seen that levers 2, 3, and 4, are all securely
locked, the points cannot be moved, nor the facing point bolt-lock
withdrawn, nor the home signal changed until the lever 1 is pushed
over again into its normal or _danger_ position. To restore the levers
to their forward position, they must be set back in the reverse order
to which they were pulled over. To simplify the explanation, only four
levers are shown in the above sketches, but the principle is
constantly extended out to a very large number of levers, and in many
cases necessitates the introduction of several rows of wedges as
indicated by the dotted lines. In some instances a combination is
effected by pulling a certain lever only half over. In some systems
the preliminary action or spring handle locking is adopted, in which
the locking is actuated by the small side lever, similar to the one
marked M on Fig. 503. The advocates of this arrangement claim
increased security and precision in the interlocking, while on the
other hand it is alleged that the mechanism is rendered more
complicated without any corresponding advantage.


Detached Lock.--Sometimes there is in the vicinity of a railway station,  333
a siding which is too far away to be worked direct from a signal
cabin, and not sufficiently used to warrant a separate cabin. Such
sidings can be worked by a small ground frame opened or locked by a
special key attached to the interlocking machinery in the adjoining
signal cabin on a double-line railway, or attached to the train staff
on a single line.

Fig. 506 shows the arrangement applied to a double line with the
outlying siding turning out of the UP main line, the points lying in a
trailing direction for the running trains. Before the special and
_only_ key can be withdrawn from its seat in the interlocking frame of
the signal cabin, all the UP main line signals must be set to
_danger_, and cannot be moved from _danger_ until the key is restored
to its proper seat again. When the key is removed from the signal
cabin, it can be taken to the ground frame at A, inserted in the key
opening, and by turning it partly round, will release the bar which
locks the levers of the facing point bolt-lock and the points. When
these two levers are free the points can be opened, and vehicles moved
into or out of the siding B C, but the special key cannot be withdrawn
from the ground-frame A, until the points and facing point bolt-lock
are put back again into their normal position for main line working.
When the operations at the siding are completed, the special key can
be removed, and taken back to its proper place in the signal-cabin,
and ordinary working be resumed.

Fig. 507 shows the application of the detached locks on a single line,
and is a sketch of a portion of railway on which there is a small
station B, with a goods siding F G, where the traffic is too small to
require anything more than ground frames and detached locks. An
engine-driver before leaving the station A, receives a train staff,
which gives him possession of the line as far as C, including of
course the intermediate station B, and this staff he must carry with
him and hand over to the signalman on his arrival at the end of the
section at C. At each of the points D and E is placed a two lever
ground frame, similar to the one shown in Fig. 506, and attached to
the train staff is a key, which will operate either of the two ground
frames, but only one at a time, as the key must be inserted before the
levers can be moved. When the train is proceeding in the direction
from A to C, it will be more convenient to shunt vehicles into or out
of the siding F G, by means of the points E, but when proceeding from
C to A, the points D will be more convenient. Whichever of the points     334
be used, they must be set, and bolt locked for the main line before
the train staff and its key can be withdrawn from the ground frame and
restored to the engine-driver. As the siding is _trapped_ at F and G,
it is impossible for any vehicles to be moved out on to the main line
except through the medium of the train staff and key. The same
arrangement of detached lock is equally available for a single siding
with only one set of points.


Electric Repeater.--It will sometimes occur that on account of a curve
or other obstacle, the arms and back lights of a distant or other
signal cannot be seen from the signal cabin, and it is necessary to
introduce an electric repeater. This little instrument consists of a
miniature semaphore signal fixed in a metallic box with a glass front,
and placed on a stand about a foot above the floor level immediately
in front of the signal lever for which it is intended to serve as an
indicator. Like the signal proper, the normal position of the
miniature semaphore is at _danger_, but when the signal lever is
pulled over in the cabin, the rod that pulls down the arm on the
signal post effects a contact with an electric circuit which lowers
the arm of the miniature semaphore at the same moment that the signal
arm proper is lowered, and gives visible indication in the cabin that
the signal is working. Fig. 508 is a sketch of one form of electric
repeater.


Detonators or fog signals are largely used in foggy weather and
snowstorms, when the out-door signals cannot be seen from an
approaching train. At such times the atmosphere is so dense, and the
surrounding objects so obscured, that an engine-driver is totally
unable to distinguish the usual landmarks which guide him on the
approach to a station or semaphore, and he might easily pass by a
signal unless he received an audible signal to indicate the position
of the one that is invisible. Detonators are usually made in the form
of a circular tin or metallic case about two inches in diameter, and
three eighths of an inch thick, with soft metal clips on opposite
sides for bending over and securing to the rails. The case is filled
with detonating powder, which is crushed by the first wheel passing
over it, and explodes with a loud report. It is customary to use these
detonators in pairs placed a short distance apart in case one of them
should fail to explode.

Fog-signalling regulations vary on different railways, but the            335
arrangements are generally carried out somewhat in the following
manner. During the prevalence of a fog or snowstorm, a fog signalman
is placed near each of the signal-posts to be protected, and is
supplied with a hand signal-lamp, hand-flags, and a packet of
detonators. So long as the arm of the signal-post at which he is
alongside stands at _danger_, he must keep two detonators on the rail
of that line which the signal controls, and also show a RED
hand-signal (hand-flag by day, and hand-lamp after dark) to the
approaching train. When the signal arm is lowered to show that the
line is clear for the passage of the train, the fog signalman must
remove the two detonators, and show a GREEN hand-signal (flag, or
lamp) to the approaching train. When an engine driver hears the report
of a detonator crushed by his engine, it is his duty to shut off steam
immediately, and bring his engine to a stand, after which he must
proceed very cautiously, until he receives further signals by hand or
otherwise, or receives the line-clear signal to continue on his
journey. Detonators are also of great service both in fine or bad
weather, in cases of a wash away, a failure of works, or obstruction
on the line, when a hand-signal may not be seen, but a detonator must
be heard.


Mechanical Gates.--Mechanical gates, worked and controlled from the
inside of a signal-cabin, are now very largely adopted for public road
level-crossings instead of ordinary hand-gates, opened and closed by a
gateman walking from side to side of the line across the rails. Being
worked from inside the cabin, they remove all possibility of the
gateman being struck by a passing train; they move simultaneously, and
can be opened or closed in very much less time than hand-worked gates,
which have to be moved one by one, and being interlocked with the
signals, the mechanical gates cannot be placed across the lines of
rails until the train-signals in each direction are set at
_danger_. When set for either train traffic or public road traffic,
the gates are held firmly in position by metal stops, rising out of
cast-iron boxes lying flush with the ground, and worked by a separate
lever in the signal-cabin.

Assuming the gates to be set for train traffic, and it is desired to
open them for the public road traffic, the first operation will be to
pull over the levers, and raise the signals in each direction to
_danger_, and thus release the stop-lever, which can then be pulled
over, to lower the gate-stops and allow the gate-winch to be turned,
and the gates moved round into correct position. The stop-lever must      336
then be set back to raise the stops and hold the gates secure. The
train-signals will be retained at _danger_ by the interlocking
gearing, and cannot be lowered until the gates are set back again
across the public road, and the gate-stops raised.

It is frequently urged that the celerity with which mechanical gates
can be swung round and closed across the public road, is in itself a
source of danger, and that persons preparing to cross the line might
be struck by a moving gate, unless they received a distinct warning
that such closing was about to take place. There is no doubt persons
have been struck by such gates when closing across the road, and heavy
claims for injuries have been decreed against railway companies, who
were unable to prove that the man in charge had called out or given
warning before moving the gates. To ensure that due and undeniable
warning shall always be given, a firm of signal-makers have patented
an appliance by which a powerful electric gong, fixed on the top of a
tall post close to the gates, is sounded automatically by the gate
machinery itself, and before the gates actually commence to move. As
previously described, the pulling over of the lever to lower the
gate-stops is the first operation to be performed whenever it is
necessary to change the position of the gates, and it is the pulling
over of this lever which actuates the apparatus, by bringing two
electric points into contact, and thus starting the ringing of the
gong or alarm. The gong continues to sound until the gates are moved
over, the gate-stops raised, and the stop-lever put forward again into
its normal position. The arrangement is very simple and very
effective, and being purely automatic must work as regularly as the
stop-lever. The tone and volume of the gong can be varied to suit
circumstances. The public soon become familiar with its sound, and
recognize its meaning.

[Illustration: Fig. 509, 510]

Figs. 509 and 510 give sketch plan and elevation of a set of
mechanical gates for a public road level crossing on a double line of
railway. The signal-cabin should be placed within a few yards of the
gates, to enable the man in charge to have a good view of the persons
and vehicles passing over the roadway. The underground gearing for
working the gates and stops, must be protected by iron or wooden
casing. The swinging portion of the wicket gates is closed, and held
by a separate lever. The gates shown on the sketch are for a crossing
on the square, but they can be equally well arranged for an oblique       338
crossing, and of widths to suit the locality.


Block-Telegraph Signalling.--However complete the outdoor signals and
interlocking at any station, they can only control the movement of
trains within their range, and something more is requisite to ensure
the safe working of the traffic over the long lengths of line between
stations. For some years a time-interval was allowed for the working
of trains following one another on the UP and DOWN lines of a
double line railway, no train being allowed to leave a station sooner
than a fixed number of minutes after a previous train had started in
the same direction. With this system there was always the risk that
the first train might be overtaken and ran into by the second, and
especially in the night time, or when the atmosphere was at all foggy.
The electric telegraph was then called in to assist in the
train-working, and brief telegrams were passed between the stations
announcing the departure and arrival of trains. The increased security
and convenience thus obtained led to the introduction of special
electric telegraph instruments, devoted to the exclusive duty of
train-working. These instruments, termed block telegraph instruments,
are now almost universally used on all double lines of railway, and
have largely contributed to the safe and efficient working of an ever
increasing traffic. They are made in various forms, but the object of
each is to ensure that before any train is allowed to start from, or
pass any station, the signalman at that station shall receive from the
signalman in the cabin in advance a distinct visible signal that the
line is clear, and free of any train up to the cabin in advance; and
also that after the train has been despatched, the signalman in the
rear shall be at once advised when the train has arrived at the
signal-cabin in advance. Fig. 511 is a sketch of one type of
block-telegraph instrument, in which the leading feature is the
miniature signal-post with its two arms, an arrangement which readily
appeals to the eye of the signalman as being so similar in form and
action to the fixed signals in the station. Each instrument is
supplied with a bell or gong, by which the adjacent signalmen can
communicate with each other, in accordance with a fixed code of
signals which defines the relative numbers of strokes of the bell or
gong, to represent certain regulation calls and answers. In the
signal-cabins of the intermediate stations, two block-telegraph           339
instruments are required, one for the section of the line to the left
hand of the cabin, and the other for the section to the right. At the
terminal stations only one instrument is required.

In the instrument shown in Fig. 511, the upper arm of the miniature
signal-post is coloured RED, and is moved by electricity through the
medium of the block telegraph instrument in the signal-cabin in
advance; and until this RED signal be lowered to the _line clear_
position by the signalman in the cabin in advance, no train must be
allowed to start from or pass the cabin in the rear. The lower
signal-arm coloured WHITE is lowered by the plunger A on its own
instrument by the signalman in charge, and at the same moment lowers
by electricity the upper or RED arm of the block-telegraph instrument
in the signal-cabin at the other end of the section. The lower or
WHITE arm is thus restricted to the signals sent away from the
signal-cabin, while the upper or RED arm is restricted to signals
received in the signal-cabin. In the centre there is a round handle B,
which rotates a circular disc inside the instrument, and on this disc
are painted three distinct train inscriptions, only one of which can
be seen at a time through the glazed opening. One inscription has the
words ALL CLEAR painted in black letters on a WHITE ground; another
has the words TRAIN ON LINE painted in white letters on a RED ground;
and the third has the words TRAIN OFF, BUT SECTION BLOCKED painted in
black letters on a GREEN ground. The instrument is considered to be in
its _normal_ position when the GREEN inscription is in view, and both
the miniature signal-arms raised to _danger_.

Fig. 512 represents a portion of double line divided out into sections,
or working blocks, between the stations B, C, and D. Each station is
provided with the necessary block-telegraph instruments, and the usual
distant, home, and starting semaphore signals.

[Illustration: Fig. 511, 512, 513]

Fig. 513 is a diagram sketch showing the pair of instruments as they
stand on the instrument-tables in the signal-cabins B and C, where B^2
and C^1 are the instruments which work together for the block section
BC. Supposing a DOWN train proceeding from A in the direction of F,
and approaching the signal-cabin of the block station at B, the DOWN
starting signal standing at _danger_; then by the code of signals on
the bell or gong the signalman at cabin B would communicate with the
signalman at cabin C, to obtain _line clear_, so as to allow the          341
approaching train to proceed on to C. If the previous train in the
same direction had already passed C, and there was not any obstruction
on the line, the signalman at C would give _line clear_ for the DOWN
train, and to do so he would turn his circular disc to show the WHITE
inscription ALL CLEAR, and then push in the plunger of his C^1
instrument, lowering the DOWN or white arm, K, of his own instrument
to the position shown by the dotted lines, which operation would at
the same moment lower by electricity the DOWN or red arm, G, of the
instrument B^2 in cabin B to the position of the dotted lines. The
signalman at B would then lower his starting signal, to allow the DOWN
train to proceed on towards C, and immediately the train had passed
the starting signal he would, by means of his bell or gong advise the
signalman at C that the train had entered the section, or block BC,
and the signalman at C would at once turn his circular disc to show
the RED inscription TRAIN ON LINE, and use his plunger to raise to
_danger_ the DOWN or white arm, K, of his own instrument, and at the
same time raise by electricity the DOWN or red arm, G, to danger in
the instrument B^2 in cabin B. The section BC would then remain
blocked until the DOWN train had arrived, or passed the station C,
when the signalman there would, by means of his bell or gong advise
the signalman at B that the DOWN train had passed out of the section,
and would turn his circular disc to show the GREEN inscription TRAIN
OFF, BUT SECTION BLOCKED. Both instruments would then be in their
_normal_ positions, with the arms raised to danger, and ready for
further train operations. In a similar manner for the UP-line trains
on the section or block between C and B, the signalman in B cabin
would turn his circular disc, and use his plunger to lower the UP or
white arm, H, in his own instrument, B^2, and at the same moment lower
by electricity the UP or red arm, I, of the instrument C^1 in cabin C,
the other operation for train on line and train off being carried out
for the UP train in the same routine as for the DOWN train. The
outdoor fixed signals, or distant home and starting semaphore signals,
have all to be worked to correspond to the block telegraph signals,
and as the latter are always received well in advance of an
approaching train, it follows that when the line is clear, the outdoor
signals can be lowered so as to allow a through or non-stopping train
to pass a block-telegraph station at full speed.

Where the traffic is moderate, it may be sufficient to have               342
block-telegraph instruments at each of the stations, but with a very
frequent train service it will be found necessary to divide the line
into shorter sections, and erect signal-cabins and block-telegraph
instruments at intermediate points between stations.

The code of bell or gong signals is extended to include various
matters in connection with the train-working. For example, when a DOWN
train is passing cabin B at full speed, the signalman may observe that
there is something wrong--a carriage or waggon on fire, a tail-lamp
missing, or other irregularity. It is too late to stop the train with
his own signals, but by means of his bell or gong he can call upon the
signalman in cabin C to stop and examine the train, and the DOWN
distant and home signals at C can be raised to _danger_ before the
train reaches the cabin at C.

In every block-telegraph signal-cabin there is a train-book in which
the signalman has to write down the time and description of every
arriving or passing train, and, as this book lies before him, he has a
complete record of the train-working, with the particulars of the
exact times when the _line clear_ signals were given, and also when
the train arrived or passed his signal-cabin.

To guard against the possibility of a signalman inadvertently giving
_line clear_, or allowing another train to pass his cabin before the
previous train had reached the signal-cabin in advance, some railways
have adopted the lock and block system. By this arrangement the
starting signal at any cabin is electrically and mechanically locked
from the cabin in advance, and can only be released or lowered by the
action of the outgoing train itself when passing over a treadle or
other appliance connected with the rails of the running-line at the
signal-cabin in advance. This method practically gives the train the
complete control of the section; and any signalman attempting, in
error, to lower his starting signal would find it to remain fixed to
_danger_ and immovable, until released by the arrival of the
train at the advance cabin.


Train-staff for Single Line.--When there is only a single line of
railway for both an UP and DOWN train-service, very definite
precautions must be adopted to prevent the meeting or collision of
trains travelling in opposite directions. Where the piece of single       343
line is short, and can be worked by one engine in steam, or two
coupled together, no collision can take place, as the train-service
will be limited to the one train moving backwards and forwards over
the section; but with a long length of single line, including a large
number of stations, necessitating several trains, some clear and
comprehensive regulations must be introduced. For a long time the
simple train-staff was found to give the desired security; there was
only one staff for each pair of adjoining staff-stations, and no train
was authorized to run without the staff, and as the staff could only
be on one train at a time, the precaution against collisions was
looked upon as complete. These staffs, which were generally made of
brass, or other metal, were sufficiently large to be conspicuous when
placed in the stand prepared for them on the engine. They were
lettered to correspond to the stations to which they belonged, and
were made in different patterns to distinguish them for their
respective sections. No train was allowed to start from a station
until the engine-driver received from the station-master the proper
staff to authorize him to proceed to the next station, and on his
arrival there it was the duty of the engine-driver to hand over the
train-staff to the stationmaster of that place, and wait for another
train-staff to authorize him to proceed over the next section. So long
as the train service could be evenly arranged, and that there was
always an UP train to take back a train-staff which has been carried
out by a DOWN train, the simple staff worked most efficiently; but as
the traffic increased, and two or more trains had to be despatched in
the DOWN direction before one had to run in the UP direction, some
auxiliary arrangement had to be introduced. This was effected by
issuing train tickets, kept in a locked-up box, which could only be
opened by the key attached to the train-staff. A properly dated
train-ticket was handed to the engine-driver of the first DOWN train,
and, if necessary, a second train-ticket to the engine-driver of a
second DOWN train, and then the train-staff itself was handed to the
engine-driver of the third DOWN train. There were one or two serious
drawbacks to this train-staff and ticket-working. As there was only a
time interval between the starting of the trains, the one train might
overtake and run into the other with disastrous results. Again, a
second or third train, which was put down in the schedule, might be
withdrawn at the last moment, and the staff left behind at a station
when it was required at the opposite end of the section, thus causing     344
much confusion and delay. The ordinary electric telegraph could have
been utilized to assist in regulating these train movements, but it
was felt that a mere telegraph message was not sufficient to ensure
positive safety, and that something more tangible was required in the
shape of a staff, or token, without which no train should be allowed
to travel on a single line of railway. To meet this requirement, the
electric train-tablet, and the electric train-staff instruments have
been invented, each of them being so arranged that upon any one
section, or pair of instruments, a tablet or train-staff may be taken
out from the instrument at either end of the section, but when once
taken out, no other tablet or train-staff can be withdrawn from either
instrument until the first has been delivered and placed again in one
or other of the two instruments.

Figs. 514, 515, and 516 are sketches of an electric train-staff
instrument which has been very largely adopted on single lines, both
at home and abroad.

In a similar manner to the block-telegraph instruments for double
line, the electric train-staff instruments have each a bell or gong by
which the adjacent signalmen can communicate their calls and answers
in accordance with a regulation code. In the signal-cabins of the
intermediate stations two instruments are required, one for the staffs
belonging to the section to the left of the cabin, and the other for
the staffs of the section to the right. At a terminal station only one
instrument is required.

[Illustration: Fig. 514, 516, 515, 517]

The head of the instrument contains the electrical and mechanical
locking apparatus which controls the withdrawal of a train-staff, or
is acted upon by its insertion. The circular name-plates and pointers,
together with the galvanometer in the centre, serve as indicators to
guide the signalmen in carrying out the various operations. The staffs
usually consist of thin steel tubes, solid at the ends, with metal
rings fixed upon them, as shown in the sketch, the number and position
of the rings varying according to the section or pair of staff
stations to which they belong; this difference in the rings
effectually preventing the possibility of one set of staffs being used
or inserted in either of the instruments of the adjoining sections.
The staffs rest normally in the long vertical slot A, with the rings
fitting in vertical grooves, which prevent the removal of any staff
except by passing it along the curved slot BC, and out by the opening     346
D, of large diameter. The electrical and mechanical locking apparatus
is placed at the curved slot, and until the locking-bolt, which stands
across the passage of the curved slot, be lifted by the joint
operations of the signalmen and their instruments at both ends of the
section, no staff can be withdrawn. When the instruments are standing
in their _normal_ position of “staffs in,” the signalmen can arrange
between them to withdraw a staff--say either from the NORTH cabin
instrument or from the SOUTH cabin instrument of the section, but only
from one of them; and the act of taking out that staff automatically
locks both instruments, and prevents the possibility of taking out any
other staff from either instrument until the staff already removed is
restored and inserted in one or other of the instruments. From the
above description it will be seen that the electric train-staff
instrument provides for the safe working of two or more trains
proceeding, one at a time, in the same direction over a section of
single line, each one being supplied with a train-staff, which must be
handed over at the end of a section before another staff can be issued
for a following train. Should the train-staffs accumulate in one
instrument, in consequence of more trains running in one direction
than another, a re-distribution of staffs is effected by the
authorized persons according to fixed regulations.

In the diagram sketch, Fig. 517, a piece of single line is shown
divided into sections or blocks, with loops or passing-places at the
stations. At the station E a train-staff taken out of the instrument F
serves for the section up to the instrument L at the station H; and on
the train-staff is a key which will open the detached locks on the
points of the small intermediate station, G, as described in Fig. 507,
in connection with the working of detached locks. At the station H the
engine-driver receives another staff from the instrument M, which
takes him to the instrument N at station K, and in like manner on this
staff is a key which will open the detached lock on the colliery
siding points at I. At stations H and K are shown loops, or short
pieces of double line, with platform to enable an UP train to cross or
pass a DOWN train. The distance apart of the electric train-staff
stations will depend greatly upon the number of the trains, and for a
frequent train-service it may be necessary to have the instruments at
every station, whether large or small. The electric train-staff is of
great advantage in the working of ballast or construction trains, as      347
a staff may be taken out of the instrument F at station E, which will
give possession of the section as far as station H, and when the
ballasting operations--which may be very near to E--are completed, the
train can return to E, and deliver the staff again to the instrument
F, instead of having to run the entire distance to station H. Although
carrying a train-staff, the engine-driver must approach stations
cautiously, and obey the fixed signals in the usual manner.




  CHAPTER VIII.                                                           348

  Railways of different ranks--Progressive improvements--Growing
  tendency for increased speeds, with corresponding increase in
  weight of permanent way and rolling-stock--Electricity as a
  motive-power.


Looking at railways in their present stage of development, they appear
to be divided into three ranks, each one distinct from the other as
regards its importance, capability, and prospects.

In the first rank are the great trunk lines, which, at home or abroad,
pass through thickly populated districts, rich in manufactures,
minerals, or shipping industries, with their enormous movement of
materials and people, and consequently requiring the most ample works,
equipment, and appliances for security.

In the second rank may be classed those railways which run through
ranges of country where the population is moderate, or where the
manufacturing industries are few in number and of minor importance.
Although of the utmost value to the community of the long series of
small towns and agricultural districts through which they pass, and
forming the only great commercial highway, or connecting link, with
some distant seaport, or leading business centre, the traffic returns
upon such lines are too small to permit of the introduction of the
more complete appliances and luxuries to be met with on the richer
railways. In newly opened-out countries, and in distant colonies, such
lines have often to struggle on for years against financial returns so
small as to barely enable them to maintain a condition of efficiency;
but where there are natural advantages in soil and climate, combined
with a judicious development of all the available resources, the
result will be the raising of the standard of the railway itself, and
the enrichment of the entire district through which it passes. When
laying out lines of this description, it may be necessary to curtail
as much as possible the expenditure on works and equipment, but there
should be no hesitation in obtaining liberal quantities of land for
future enlargement of stations, or for constructing additional            349
stations on promising sites. The value of the land may be small in the
outset, but will be enhanced enormously as the benefits of the
undertaking become appreciated.

In the third rank may be grouped those branch lines which, starting
from a main passenger or goods line, are laid down to some outlying
town, seaport, or mining centre, which, although small, is considered
of sufficient importance to be brought into railway communication. In
general, these lines are laid to the same gauge as the line with which
they connect, and the transfer of merchandise waggons is readily
effected at the point of junction. Others, from motives of economy,
have been laid down to a narrow gauge, involving the transhipment of
all goods and cattle at the station where the break of gauge takes
place. Most of these branch lines are laid out through the open
country, like an ordinary standard railway, but with a minimum of
works and appliances. Others are laid down partly on level public
roads, and partly through the fields, and are in consequence subject
to a statutory low rate of speed when travelling over those portions
on the public roads.

In many cases the construction of second and third rank railways, both
at home and abroad, has been largely assisted by state or provincial
aid. Such assistance must always be valuable to poor or undeveloped
districts, but judgment should be exercised so as not to encourage the
introduction of any scheme which would interfere or become competitive
with any existing undertaking constructed by public enterprise. So
long as capitalists invest their money more from commercial motives
than from feelings of philanthropy, it would, to say the least, be
unjust and impolitic for any country to adopt a course of competition
by national funds, and so check the flow of public money into public
undertakings. Ordinary public commercial competition may be business,
as each party can value and compare their own prospects; but the
competition of a scheme enjoying national aid and free money grants is
very apt to become one-sided.

There is every indication that even what may be termed a fourth-rank
type of railway is destined to play a very important part in the
industrial enterprises of many countries, and that in the form of
little lines, made to any convenient gauge, and laid either along
public roads or open country, or both, the produce from isolated
manufactories, forests, quarries, and large farms will be conveyed to     350
the nearest railway stations with greater facility and at much less
expense than by carting along the public highway. Such little lines
are available in places where the most sanguine promoter would
hesitate to suggest an ordinary railway, and may be found to supply
what is felt to be the missing link in the economical transport of a
long list of materials of everyday use. As they would be almost
exclusively intended for merchandise purposes, the statutory
requirements would be on the most moderate scale, and as they would be
generally constructed at the cost of the parties who had to operate
them, the outlay would be restricted to the actual works necessary for
convenience and efficiency. Similar little lines have been in use for
many years in the busy yards of large ironworks, shipbuilders, and
many other localities, where weighty masses of materials have to be
moved from place to place in the course of manufacture, and it would
be merely carrying out the same idea to a more extended range. The
principal inducement for their introduction is the great advantage,
both in convenience and cost, that is obtained by hauling a ton of
materials over a pair of rails as compared with carting the same
weight along an ordinary road; and as the fact becomes more and more
proved by experience, these little fourth-rank lines will become more
general. Numbers of them are in use at the present time, and some of
them, even of only 2-feet gauge, are doing good service, the little
trucks conveying manufactured goods to the nearest railway station and
returning loaded with coals and other materials. By making suitable
arrangements for passing places and junctions, the system could be
carried out to considerable distances in thinly populated districts,
and be made available by means of local sidings, to several places
along the route. With a narrow-gauge type there would, of course,
always be the time and expense of transhipment to or from the ordinary
railway trucks in the same way as with the road carts, but the time
and expense may be lessened by so constructing the little narrow-gauge
trucks that the bodies may be readily lifted off the frames and
wheels, and be placed like packing-cases in the railway waggons.

It is natural to look to the railways of the first rank for the latest
advances in construction, appliances, and equipment, and it is
generally there they are found. Great trunk lines, crowded with
traffic of all kinds, have not only the opportunity and means, but all
the strong inducements to try or adopt any arrangement which promises     351
greater facilities for dealing with the ever-increasing demands made
on their carrying powers.

Passenger and goods traffic are so dissimilar in their requirements
that when both of them are steadily increasing it becomes difficult,
if not impossible, to work the two classes over an ordinary double
line. In some cases much assistance has been obtained by shortening
the lengths of the working sections and introducing intermediate
electric telegraph block stations between the ordinary stations. Long
refuge-sidings have also been introduced at many of the signal-cabins
or stations, into which goods trains can be shunted out of the way to
allow fast passenger trains to pass through without stopping. Up to a
certain extent this arrangement works fairly well, but where there is
a very frequent service of fast and slow passenger trains, combined
with a heavy and constant service of goods and mineral trains, the two
lines of way are practically incapable of accommodating such a number
of mixed trains without causing serious detentions. The goods trains
must shunt out of the way some time before a passenger train is due,
and this frequent shunting into sidings results in hours of delay in
the transit of the goods and cattle traffic; and when one of such
trains is allowed to proceed again on its way up to another station,
dove-tailed as it may be between two fast passenger trains, there is
always the tendency to run at a much higher rate of speed than is
prudent for the class of rolling-stock of which the goods train is
composed. To overcome this difficulty some railways have introduced
additional UP and DOWN lines on the busiest part of their system,
making four lines of way in all, two of these being reserved for the
fast passenger and through trains, and the other two for slow trains,
goods, and mineral trains. This arrangement of the four lines has
afforded great relief to the traffic of all kinds, and has enabled the
service to be worked with much greater facility and punctuality. The
goods trains being restricted to their own separate lines, can proceed
regularly in their order, at their uniform working speed, without
having to resort to the spasmodic fast running too often expected from
them when passing over some parts of an ordinary double line.
Doubtless this four-line system, or rather the principle of laying
down two additional lines of way, will go on extending, and will be
accelerated in its accomplishment by the growing demand for still
higher speed of our fast passenger trains, and still longer distances
to be traversed without stopping. High-speed long-distance through        352
trains can only perform their journeys with punctuality, when the
route is kept clear of all other trains or obstructions which might
interfere with their free running. Any check or stoppage in their
course would cause loss of time and prestige.

It is to be regretted that in so many of the cases where two
additional lines of way have been laid down, more space was not left
between the sets of rails for the fast traffic and those for the slow.
In many instances the dividing space is not more than 7 or 8 feet. It
would have been better and safer if it could have been made 20 feet.
An ordinary goods train is made up of several kinds of trucks, some
empty, some loaded, many of them unequally loaded, all of them subject
to heavy work and rough handling, and more likely to give trouble than
the higher class vehicle, the passenger carriage. The breaking down or
derailment of one or two goods trucks on a line of rails close
alongside the fast passenger rails, would in all probability so foul
and obstruct the passenger line as to cause a very serious accident to
an express train which could not be stopped in time. The greater width
would not only provide more clearance in case of breakdowns, but would
afford increased safety to the platelayers and other workmen engaged
on the line. The permanent-way men have to be very watchful to keep
out of danger on an ordinary busy double line, but they must be very
much more on the alert where there are four lines of way close
together side by side.

In the neighbourhood of large cities and important manufacturing
centres, railways have created a distinct traffic for themselves by
providing means for a large portion of the population to reside in
convenient suburbs. Local trains running at suitable business hours
have induced people of all classes to select homes a few miles away
from town, and the gradual growth of this suburban traffic has
produced its own advantages and requirements. At the large terminal
stations platform after platform has been added to accommodate the
increased number of trains which arrive in the busy parts of the
morning or depart in the evening. Every facility has to be provided to
permit of the expeditious ingress and egress of the large crowds
forming the respective trains--ample platforms, over-line
foot-bridges, subways, convenient booking-offices, waiting-rooms, and
left-luggage rooms.

The enormous train service on some of these first-rank lines demands      353
the highest efficiency in the signalling and interlocking
arrangements, and the use of any devices which will ensure increased
facility and safety in the working of the traffic. With a crowd of
trains passing a signal-cabin in both directions, and often over four
lines of way, it is quite possible for a signalman to make a mistake
which cannot be rectified in time to prevent an accident. To obtain
increased security many railways have adopted the lock and block
system previously described, or some adaptation of the same principle,
and this method of working will go on extending as the traffic
increases. These additional appliances entail additional care and
inspection, for although automatical machinery may be exempt from the
human frailty of preoccupation of mind or forgetfulness, it is
somewhat delicate in its organization, and requires constant
supervision to maintain its efficiency.

On many of the large lines, much has been done to give improved
carriage accommodation. Carriages have been made longer, easier on the
road, loftier, better furnished, and better lighted; but there is
still a very great deficiency in those conveniences so essentially
necessary, especially on trains running long distances without
stopping. Drawing-room cars and dining-room cars are no doubt
attractive, and may contribute considerably to the popularity of
certain routes; but it is questionable whether many of the lines at
home and abroad which have adopted such luxuries, have not in doing so
commenced at the wrong end, and whether it would not have been more to
the public satisfaction to have begun by first providing those
conveniences which are found in every carriage on every line in the
United States. It is satisfactory to find that there is a steadily
growing tendency to so construct passenger carriages that their
occupants may, by passages or corridors, communicate with all parts of
the same carriage or with the adjoining carriages; and there is every
reason to assume that the carriage of the future, either by
legislation or consent, will combine both the items of conveniences
and intercommunication, and will confer not only greater comfort to
the passengers, but also increased protection against those outrages
which, unfortunately, too frequently occur under the system of
isolated compartments.

It will be instructive to watch the results of the passenger receipts     354
on those lines where only first and third-class carriages are used.
The elimination of the second class may at first sight appear an
innovation; but if there is not any pecuniary loss sustained, there
must be a gain in the reduction of unoccupied seats to be hauled. It
is customary to provide in every train a liberal number of spare seats
of each class to meet contingencies; and the omission of one class may
mean the saving of two or three carriages--a very important item in
locomotive power.

On important through lines high-speed running has become a leading
feature, and compels a very efficient standard of perfection in works
and rolling-stock to effect its attainment. There is no indication of
remaining contented with what has been already accomplished; on the
contrary, the spirit of restlessness is always urging to do something
more. The travelling public speak as calmly now of a speed of seventy
miles an hour as they did of thirty-five a few years ago; they
thoroughly recognize the value of railways, and they merely desire to
travel still faster. The incentives of emulation and competition are
ever present to encourage further and further reduction of the running
time, and the railway that offers a special fast through service for
some of its passenger and mail trains, reasonably expects its
popularity and patronage to be in the ascendant. Much has been done in
permanent way and equipment to make the present high speeds possible,
but more will be required if the speeds are to go on increasing. The
passenger carriages for such work must be very substantial, and
naturally heavy. The locomotives to haul a long train must have
increased power and weight, and will necessitate stronger rails to
carry the greater rolling loads. With the present system of
motive-power, the heaviest item is the locomotive, and its weight must
always determine and regulate the character of the works and permanent
way. Rails weighing 90 pounds per yard are becoming common, and there
is clear indication that before very long sections weighing from 100
to 120 pounds, or more, per yard will be brought into use on many
lines. There will be no difficulty in making a permanent way strong
enough for rolling loads very far in excess of anything in the present
practice; but it will be costly, and the extra expense per mile,
extended over a few hundred miles, will represent a sum so large as to
raise the question in many cases whether the probable advantages and
additional remuneration to be obtained will warrant the outlay.

To some extent the increased speed may be attained by dividing the        355
present long trains into two shorter trains, with a fair interval of
time between them. There are many splendid locomotives now running,
which on a fairly level line can reach a speed of considerably over
seventy miles an hour with a short train, but would be quite incapable
of doing so with a long train. At the same time it is possible that if
passengers increase in the same proportion as the inducements
provided, the short train might not be sufficient for the numbers
presented, and there would be no other alternative but to resort to
still greater rolling loads and stronger hauling power.

Perhaps electricity, which has already achieved so many marvels, is
destined to take a still more prominent part as a motive-power in the
working of ordinary railways, and may help out of the difficulty by
inaugurating still higher speeds without the necessity of incurring
stronger works or heavier permanent way. In addition to its success in
the telegraph, in the telephone, and in its brilliant light,
electricity is every day coming more and more to the front as a
motive-power. At present many tramways and short lines, some of them
in tunnel, some above ground, and many of them with very steep
gradients, are successfully worked by electricity; but these, being of
modern construction, were specially designed and equipped for that
method of working, and none of them as yet resort to high speeds. Such
rapid strides have, however, been already made in the progress of this
system of haulage, as to promise that both increased power and speed
will be forthcoming when the demand for them is made manifest. Various
modes of application are being tried: overhead wires, underground
wires, conductors on the level with the rails, storage batteries or
accumulators, and self-contained electric motors, each and all of them
being carefully tested to ascertain the comparative cost and
efficiency. Much will depend upon the localities and advantages to be
obtained for the respective generating stations. In places where a
large, constant, and unutilized water supply is available, a great
saving may be effected in the most expensive item of electric working,
but in the greater number of cases steam-power will have to be adopted
for driving the generating machinery. The main question will be
whether electricity in its most approved form of application can haul
a ton of paying load for one mile at a less average cost, and at as
great or greater speed than the ordinary locomotive. Until there is       356
very clear evidence that electricity is cheaper, there will not be any
great inducement for its general use as a motive-power on ordinary
railways.

Experiments have been made on some existing railways to ascertain how
far this new motive-power can be made serviceable under special
circumstances. In one case, a powerful electric motor-car has been
introduced for working frequent and heavy trains through a long
tunnel, where the atmosphere with ordinary steam locomotives became
foul almost to suffocation, and the result has shown that the traffic
can be hauled efficiently by electricity, and the air in the tunnel
maintained pure and clear. In this instance, the question of cost was
of secondary importance, the primary object being to avoid the
asphyxiating gases emitted from the ordinary locomotives.

In other cases, specially designed electric motor-cars have been
constructed with a view to obtain a higher speed for passenger trains
than is at present attained with the locomotives, and the trials made
have proved that these cars could reach a high speed, but so far only
with limited loads. Experiments are still going on with larger and
improved machines, from which it is expected to obtain both high speed
and much increased hauling power.

It is more than probable that amongst the earliest practical
applications of electric motive-power on existing railways will be its
introduction as an auxiliary on the steep gradients of some of the
mountain railways abroad. In many of these regions there are millions
of gallons of water running to waste down the ravines, a portion of
which could be utilized in working powerful generating plant, to drive
strong electric motor-cars for assisting the ordinary locomotives up
the steep inclines. In such localities, with free water-power, the
cost of the electricity would be at a minimum, while the cost of the
ordinary locomotive would be at a maximum.

In whatever form the electric motor-car may be designed, we are
brought face to face with the old axiom, that there must be a certain
amount of weight to obtain a certain amount of adhesion; but there
will be one important point in favour of the motor-car, that whereas
in the ordinary locomotive the weight for traction can only be
distributed over a few working wheels, the electric arrangement may
distribute it over a much greater number, and so diminish the
insistent weight of each wheel upon the rails. There would also be the    357
saving of the dead weight of the tender, the fuel, water, and other
minor accessories, as well as the advantage that the active power
would be applied in a rotary form instead of reciprocating.

There are important interests at stake in the perfecting of this new
system of haulage, and day by day new developments are being made to
add to its efficiency and reduce its cost. Existing railways will,
however, naturally require some very convincing proof of the all-round
superiority of electricity before adopting that power generally
in place of their present locomotives. The latter, with their
corresponding workshops and appliances, represent so large an amount
of invested capital, as to demand most thorough trials and
investigation of the new power before they are superseded;
nevertheless, if further experience proves that electrical power is
better and cheaper than the ordinary steam locomotives, then the
change will undoubtedly be made.

Under whatever system of haulage the acceleration of trains be
obtained, the increased speed will call for increased precautions in
the selection and proving of the materials to be used in such service.
Rails must be made more uniform in quality, and must be free from the
imputation of fracture under regular wear. Notwithstanding the great
improvements made in the preparation of the steel, and in the rolling,
there are still far too many steel rails which break under traffic to
allow rail-makers to rest satisfied with their work. Something is
still wanting in the manufacture to effectually remove this
disposition to fracture. The safe rail, the rail of the future, must
be one that may bend and may wear, but will never break under ordinary
use in the road. Axles must be stronger and tougher, as they will have
to bear greater torsional strains than are now imposed upon them; and
the wheels, of whatever type they are made, must be incapable of
collapsing or falling to pieces upon the sudden and severe application
of the brake-blocks. A train, rushing along at a speed of 70 or 80
miles an hour, may on an emergency have to be brought to a stand in
the shortest distance possible, and the failure of either axles or
wheels in the endeavour to avert one form of accident would inevitably
initiate another.

To permit of unchecked high-speed running, many sharp curves will have
to be flattened, bridges will have to be built at busy level
crossings; and points, crossings, and junctions on the main lines will    358
have to be reduced to the smallest possible number.

It would be difficult to form an opinion as to how far passenger
traffic will go on expanding, but if it continues to increase at the
same rate as at present, some railways may find it expedient, and even
absolutely necessary, to construct new lines altogether separate and
apart from the existing routes, and for the sole use of their fast
through traffic. As roadside or intermediate traffic would not form
any part of the scheme, such lines could be laid out so as to keep
away from the populous districts, where property would be costly, and
pass instead through those parts of the open country where the most
direct course and easiest gradients could be obtained. Stations would
only be required at the very large and important places, and at long
distances from each other. Lines of this description, reserved for
through traffic only, taken alone, might not pay, but taken in
conjunction with the existing lines, of which they would form a part,
they might prove to be the best solution of the problem of dealing
with a crowded train service, the remunerative earnings of which,
placed together, might yield a rich return over the entire system. A
project for a separate through line might at first appear a little
startling, but we have well-known precedents in the vast expenditure
already incurred in the constructing of enormous viaducts and
connecting lines to avoid long detours on certain through routes. The
widening out of an ordinary double line into a four-line road was at
first considered as a rather venturesome departure; and it must always
be costly because, in addition to the earthworks and permanent way,
there is the doubling of all the over and under bridges and waterways,
besides the great and expensive alterations at stations. Practically
it is almost like making a second railway, and yet the constant
extension of the principle is an admission that the working results
have proved satisfactory, in spite of the large outlay. A little later
the question will force itself more prominently into notice, whether
the four-line track or the separate fast through traffic lines, will
best answer the purpose. The former possesses certain advantages, but
the latter would give more freedom for high-speed running.

Engineers have brought railways to their present stage of perfection,
and the public will expect them to devise and carry out still further
improvements as the march of development moves onward. It is a simple     359
matter to arrange the traffic on a railway when all the works and
appliances are appropriate for the service to be performed; but the
advances which are made follow one another so rapidly as to
necessitate constant study and organization to effect the structural
alterations and additions requisite to maintain an up-to-date standard
of efficiency. The traffic manager on a railway receives his
instructions from the directors or controllers of the company as to
the working out of the train service, rates, charges, and other items
of his department, but the engineer has to stand alone, and his
technical knowledge and professional skill must enable him not only to
design and construct works suitable in character, extent, and strength
to the duty for which they are intended, but also to decide when
structures are no longer capable of properly sustaining the increasing
loads brought upon them, and must be taken down and replaced with
others of a stronger description. For this reason the engineer must
carefully consider every circumstance and local feature which may
influence the design to be prepared; he must thoroughly investigate
the nature of the ground for foundations, as the description when
ascertained will frequently determine the class of work to be erected,
whether in viaducts, bridges, or buildings; and in his selection of
materials and calculations for strength, he must allow ample margin to
meet further increased weights, as well as for natural deterioration.

He should, indeed, go a little further, and as his perceptive ability
and training will always enable him the more readily to foreshadow the
direction in which improvements or changes are tending, he should
study out and be prepared with his schemes to meet the new departures
as the requirements gradually arise.

Strength and efficiency are the leading points which must be always
kept in view, and the engineer must never forget that he is solely
responsible for the safety of the line and works, and of the public
passing over the same.




  INDEX                                                                   361


  A

  Accommodation works, 12
  Air-lock, 119
  Air-pump, 120
  Allowances for sinkage on embankments, 70
  Alteration of gradients, 12
  ---- of roads, 6, 10
  American hand-brake, 46
  Analysis of steel rails, 193
  Approach roads to stations, 249
  Arch culverts, 76
  Automatical gate-alarm, 336


  B

  Ballast, 225
  Bascule bridge, 85
  Battering-rule, 72
  Bearing-weights of various materials, 129
  Beater, 239
  Bench marks, 66
  Bissell truck, 58
  Block crossing, cast steel, 235
  ---- telegraph signalling, 18, 338
  Board of Trade requirements, 18
  Bog-cutting, 65
  Bogie carriage, 54
  ---- engine, 56, 306
  Booking-hall, 249, 260
  Book of reference, 8
  Borings for foundations, 129
  ---- for tunnel work, 164
  Borrowed earthwork, 61
  Bottom-pitching, 225
  Bracket signals, 20, 322
  Brake-power on gradients, 45
  Brakes for goods waggons, 46
  Brick-well foundations, 123
  Bridges, 79
  ---- over public roads, 10
  Broken stone ballast, 225
  Buffer-stops, 282
  Bull-head rail, 191


  C

  Cab-rank, 251
  Caisson foundations, 121
  Cant of rail, 230
  Carriage accommodation, 353
  ---- bogie, 54
  ---- dock, 282
  ---- traverser, 292
  Cast-iron column piers, 97
  ---- in bridges, 27
  ---- saddles, 224
  ---- sleepers, 214
  ---- tram-plates, 184
  ---- tube tunnels, 179
  ---- water-tanks, 299
  Catch-siding, 26
  Centre line of railway, 32
  Chairs, 206
  Channelling ballast, 231
  Check-rails on sharp curves, 29, 51
  Cinder ballast, 227
  Circular running-shed, 289
  Clay puddle, 127
  Clocks at stations, 26
  Coal-drops, 282
  Coffer-dams, 127
  Comparison of bull-head and flange rails, 199
  Compound rails, 190
  Concrete foundations, 114
  Continuous brakes, 30
  Cost of permanent way, 241, 242                                         362
  Covered-way tunnels, 178
  Crab bolts, 223
  Cranes, 280, 294
  Creosoted sleepers, 211
  Cross-over road, 233
  Crossings made of rails, 237
  Cross-sections, 33
  Culverts and drains, 74
  Curve alterations, 12
  Curves, 49
  Cutting rails on curves, 229
  Cylinder foundations, 116


  D

  Datum line, 8
  Deck or floor of girder bridges, 133
  Deposited plans, 4, 6
  Depths of cuttings, 10
  Derrick crane, 299
  Detached lock, 332
  Detonator or fog signals, 334
  Detours on mountain-sides, 3
  Deviation, limits of, 6
  ---- of centre line, 12
  ---- of levels, 12
  Diagram sketches of bridges, 149
  Diamond crossing, 237
  Disc or ground signals, 322
  ---- wheels, 48
  Distant signal, 18, 314, 322
  Diversion of roads, etc., 6
  Dobbin-cart, 67
  Dock platforms, 251
  Double-line junction, 231
  ---- slip points, 233
  Dry stone backing, 162


  E

  Earthworks, 60
  Edge rails, 185
  Electric motive-power, 355
  ---- repeater, 22, 334
  ---- train-staff instrument, 344
  Embankment on bog, 71
  Engine bogie, 53, 56, 304
  ---- triangle, 290
  Engine turntables, 27, 289
  Enlargements on parliamentary plans, 16
  Entrances to tunnels, 176
  Estimate, 14
  Expansion of rails, 228
  Extract from Government Standing Orders and Regulations, 6


  F

  Facing-bolt lock, 315
  ---- points, 20
  ---- ---- distance, 20
  ---- point locks, 22
  Fang clips, 224
  Fastenings, 218
  Fences enclosing line, 14, 73
  ---- on bridges, 10
  ---- on road approaches, 10
  Fish bolts, 203, 220
  ---- plates, 188, 203
  ---- plate liners, 206
  Flag signals, 313
  Flag-top culverts, 76
  Flange rail, 191
  Floor or deck of girder bridges, 133
  Floors for goods-sheds, 280
  Flying junction, 231
  Fog or detonator signals, 334
  Footbridges, 26, 147, 149
  Footings of foundations, 111
  Foundations, 111
  Four-line system, 351


  G

  Gantry crane, 294
  Gate-alarm, 336
  Gates for level crossings, 74
  Gauge of railways, 37, 38
  Girder bridges, 110
  Glazed roofs over platforms, 272
  Goliath crane, 297
  Goods-sheds, 273
  Government grants to railways, 349
  ---- Standing Orders, 4, 6
  Gradient alterations, 12
  Gradients, 42
  ---- influencing loads, 43
  ---- in tunnels, 166
  Gravel ballast, 225
  ---- foundations, 113
  Guard-rails, 51
  Guide-piles, 127


  H                                                                       363

  Half-round sleepers, 211
  Hand-brakes on trucks, 46
  Headings in tunnels, 169
  Headway and span of public-road bridges, 10
  Height of platforms, 24
  Heights of embankments, 10
  High-level viaduct, 81, 83
  High-speed running, 354
  Home signals, 18, 314
  Houses of labouring classes, 10


  I

  Inclination of ramps, 26
  Inside keys for chairs, 207
  Inspection of new line, 18
  ---- of tunnel work, 176
  Interlocking of signals, 22, 314, 330
  Iron-tube tunnels, 179
  Island-platform station, 258


  J

  Jack-arches of brickwork, 145
  ---- of concrete, 139
  Jib crane, 296
  Jim Crow, 239
  Junction signals, 20, 323
  ---- with existing line, 6


  K

  Keys for chairs, 207
  Kinsua Viaduct, 97


  L

  Lavatories and conveniences, 260
  Laying permanent way, 225
  Level crossings, 10
  Life of steel rails, 193
  Lift-bridge, 87
  Light railways standard gauge, 41
  Limits of deviation, 6, 16
  Loa Viaduct, 102
  Loads of locomotive engines, 44
  Location of railway, 1
  Lock and block signals, 342, 353
  Longitudinal sleepers, 210
  Low viaduct arching, 129
  Low-level viaduct, 81, 83


  M

  Made ground, 111
  Marking steel rails, 195
  Mechanical drills, 172
  ---- gates, 335
  Mile-posts, 30


  N

  Names of stations, 24
  Narrow-gauge railways, 40
  Natural features of country, 1
  ---- ground, 111
  Navigable rivers, 81


  O

  Occupation bridges, 110
  Ordinary crossing, 235
  Ordnance maps, 3
  Outside guard-rails, 53
  ---- keys for chairs, 207
  Over-line arch bridges, 103


  P

  Parapets on viaducts, 28
  Parliamentary estimate, 14
  ---- plan and section, 6, 8
  Pedestal water-tanks, 302
  Piers of cast iron, 97
  ---- of masonry, 95
  ---- of timber, 102
  ---- of wrought-iron and steel, 97
  Pile foundations, 114
  Plate-iron troughing, 143
  Platform roofs, 264
  Platforms (requirements of), 24
  Plenum system of sinking, 119
  Pneumatic process of sinking, 129
  Points, or switches, 235
  Portage viaduct, 102
  Power to purchase land, 6
  Preservation of timber, 211
  Private-road bridges, 110
  Provincial grants to railways, 349
  Public-road bridges, 10, 103
  ---- level crossing, 8


  R                                                                       364

  Radial axle-boxes, 58
  Rails, 182
  Railway bills, 16
  ---- Clauses Act, 6
  ---- fences, 14
  ---- slope, 61, 66, 72
  Railways of different ranks, 348
  Ramps to platforms, 24
  Recommendations as to working of railways, 30
  Rectangular running-sheds, 289
  Reduced speed on curves, 50
  Refuge sidings, 31, 351
  Relative costs of narrow-gauge and light railways, 41
  Renewal of under-line bridges, 151
  Repeater signal, 22, 334
  Requirements of Board of Trade, 18
  Retaining walls, 159
  Reverse curves, 51
  Roadside station, 253
  Rock foundations, 113
  Rocking-bar, 316
  Roof-principals, 264
  Roofs over roadside platforms, 272
  Rope-haulage, 49
  Route of railway, 1
  Royal assent, 16
  Runaway points, 233


  S

  Safety-points, 24, 319
  Sandy foundations, 113
  Scales for Parliamentary plans, 6, 16
  Scissors cross-over, 233
  Screw piles, 114
  Semaphore signals, 313
  Semi-circular running-sheds, 289
  Separate lines for through traffic, 358
  Service roads, 69
  Shafts in tunnels, 167
  Sheeting-piles, 127
  Side-cutting, 61
  Side recesses in tunnels, 176
  Sidings, 24
  Signal-cabins, 328
  Signal-detector, 315, 318
  Signals, 313
  ---- at junctions, 20, 323
  Signals (requirements of), 20
  Six-wheeled carriage, 54
  Sleepers, 209
  Slip-points, 233
  Slope of cutting, 61
  ---- of embankment, 66
  Slotted signals, 326
  Snake-heads, 184
  Soft deep bog, 70
  Soiling earthwork, 66
  Sorting-sidings, 285
  Span and headway of P. R. bridges, 10
  Spans of large railway bridges, 158
  Spikes, 222
  Spirals, 35
  Spoil-bank, 60
  Sprags, 46
  Square crossing, 233
  Standing orders, 4, 6
  Starting-signal, 18, 314
  Station buildings, 260
  ---- roofs, 264
  Stations, 248
  ---- near viaducts, 24
  ---- on gradients, 26
  Steel and wrought-iron sleepers, 217
  ---- rails, 190
  Steps for side-lying ground, 70
  ---- of staircases, 26
  Stone sleepers, 210
  Strain on steel, 27
  ---- on wrought-iron, 27
  Suburban traffic, 352
  Subways, 26
  Super-elevation of rail, 230
  Supervision of tunnel-work, 176
  Swing-bridges, 83, 87
  Switches or points, 235
  Syphon culverts, 79


  T

  Tamping-bar, 239
  Terminal station, 253
  Tests for steel rails, 194
  Three-throw switches, 233
  Thrust-girders for retaining walls, 161
  Tie-bars, 224
  Timber bridges, 95
  Timbering of tunnels, 170
  Timber-pile foundations, 114
  Time for construction, 18
  Tip head, 67                                                            365
  Tip-waggon, 69
  Tools for permanent way, 239
  ---- for tunnel-work, 172
  Trailing-points, 20
  Train-staff on single line, 342
  Train-tickets, 343
  Tramplates of cast-iron, 184
  Tramway rails, 199
  Trap-points, 319
  Travelling-crane, 296
  Traversing bridge, 85
  Trimming slopes, 72
  Trough girders, 135
  Tunnel faces, or entrance, 176
  ---- headings, 169
  ---- sections, 176
  ---- shafts, 167
  Tunnels, 6, 10, 162
  ---- composed of cast-iron segments, 179
  ---- drainage of, 166
  ---- through cities, 178
  ---- under rivers, 181
  Turn-out, 233
  Turntables, 287


  U

  Under-line arch bridges, 103, 129


  V

  Vacuum system of sinking, 119
  Verandah on platform, 261
  Viaduct parapets, 28
  Viaducts of timber, 95
  ---- over rivers, 83
  Viaducts over valleys, 91
  ---- to be shown on section, 10


  W

  Waggon turn-table, 292
  Waiting-rooms, 251
  Warehouse crane, 294
  Water-column, 302
  Water-jet piles, 116
  Water-tables, 227
  Water-tanks, 299
  Wear of fish-plates, 205
  Wear of steel rails, 193
  Weeping-holes, 161, 174
  Weights of locomotive engines, 304
  Well foundations, 123
  Wheel-base of engine bogie, 59
  Wheel-guards on viaducts, 28
  Widths of public-road bridges, 10
  Winding engines, 185
  Wind-pressure, 28
  Wooden-centre wheels, 48
  Wooden culverts, 76
  ---- screws, 223
  ---- tramway, 182
  ---- water-tanks, 301
  Working plans and sections, 32
  Wrought-iron column piers, 97
  ---- and steel sleepers, 217
  ---- piles, 116
  ---- rails, 186
  ---- water-tanks, 301


  Z

  Zigzags, 35




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Transcriber’s Note:

Unprinted punctuation was added, where appropriate. The illustrations
identified as numbered figures are all full-page without captions. When
illustrations interrupt the text of a paragraph, they were moved to
precede that paragraph. For ease of use of the index, page numbers are
displayed in the right margin for only pages that contain text.

Words and phrases in italics are surrounded by underscores, _like
this_. Superscripted letters and numbers are preceded by a carat, e.g.
C^o. Use of hyphens was made consistent. Obsolete and alternative
spellings were left unchanged. Spelling corrections are noted below:

  ‘transhipment’ to ‘transshipment’ ... delay in transshipment... pg 41
  ‘steepier’ to ‘steeper’ ... introduce steeper gradients ... pg 45
  ‘guage’ to ‘gauge’ ... 8½ inch gauge,... pg 48
  ‘guage’ to ‘gauge’ ... on 3-foot narrow-gauge railways ... pg 193
  ‘breaks’ to ‘brakes’ ... the working of the brakes.... pg 193
  ‘petition’ to ‘partition’ ... plate partition across ... pg 301
  ‘close’ to ‘closed’ ... is kept closed by the pressure ... pg 302





End of Project Gutenberg's Railway Construction, by William Hemmingway Mills