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Earthwork in railway

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BOUGHT WITH THE INCOME OF THE

SAGE ENDOWMENT FUND

THE GIFT OF

HENRY W. SAGE

1891

engr |
THE GLASGOW TEXT BOOKS OF CIVIL

ENGINEERING. Epitep By G. MONCUR, BSc.

M.I.C.E. Professor of Civil Engineering in the Royal
Technical College, Glasgow.

 

EARTHWORK IN RAILWAY
ENGINEERING
THE GLASGOW TEXT BOOKS.
Epitep sy G. MONCUR.

 

EARTHWORK IN
RAILWAY ENGINEERING

BY

JOHN W. F. GARDNER, M.Inst.C.E.

 

NEW YORK
D. VAN NOSTRAND COMPANY
EIGHT WARREN STREET
1922
PRINTED IN GREAT BRITAIN
PREFACE

THE purpose of this book is to describe in a practical manner the
underlying principles which control earthwork undertakings, so
far as they relate to general railway work.

It has not been possible in the limited space available to deal
fully with certain matters and preference has been given to the
points more directly affected by the actual constructional work.

In view of the uncertainty of the character of the material to
be met with, no hard and fast scheme of operations can be adhered
to, and the methods of procedure hereinafter referred to should be
taken more as a guide to what course or design to follow.

The author would emphasize the importance of thorough con-
sideration being given to drainage works, and matters relating
thereto have been given special attention.

The particulars in regard to constructional work are for the
most part the result of experience gained by the author when
acting as Resident Engineer under Mr. Donald A. Matheson,
formerly Engineer-in-Chief, now General Manager of the Cale-
donian Railway, and he takes the opportunity of placing on record
his appreciation of the valuable assistance received from him.

J. W. F. G.
CONTENTS

CHAPTER PAGE
I. Prepiminary INVEsTIGATIONS anD Estimates or Cost 1

II. INVEsTIGATION aS TO STRATA  . ‘ z ‘ 9
III. CuLverts anp DRAINAGE . ‘ ‘ . 18
IV. Execution or Eartawork : . 36
V. PLANT USED IN EXECUTING EaRTHWORK . i wm ACE
VI. Sires in EARTHWORK AND THE MEANS TAKEN TO
PREVENT THEM . : ie ‘ ‘i ‘ x 99
VII. Maintenance oF EARTHWORK . Z 7 ‘ - 127
VIII. Conpitions AFFECTING THE Cost oF HarRTHWORK . 184
IX. SpEciFicaTION . : : 4 : . . . 142

INDEX : s ‘i * ; ‘ ‘ ‘ . 149
LIST OF ILLUSTRATIONS

FIG, PAGE

1.—Cutting for single line . 2 F ‘ : : : : Z 2
2.—Cutting for double line : . : 7 3
3.—Difference between cutting for aagle et downs lies 3
4.—Chisel boring 5 z : 12
5.— Crown ” of diamond drill . 3 . : 15
6.—Water openings in embankments s % ; 2 . 21
7.—Fire-clay pipe drains under railway és 2 ‘ 22
8.—Timber box drain under railway . : 7 : » -22.
9.—Built stone drains under railway. ‘ . é 2 : - 23
10.—Arch culverts under railway 3 : 2 ‘ . . 23
11.—Culverts with steel beams and concrete covering : é 3 . 24
12.—Pipe conduit under railway embankment on side-lying ground . » 25
13.—Stepped arch culvert on side-lying ground : 3 ‘ 5 - 26
14.—Design of ends of culverts. : : . 28
15.—Two water-courses conveyed in one iatuens wees railway § . 2
16.—Water channel diverted along contour of sloping ground 3 . 3
17.—Road and stream diversion carried under railway at one place - 82
18.—Syphon pipe under railway : j 33
19.—Pipe carried over railway on trestle ‘ 2 ‘ r . 84
20.—Pipe carried over railway on road bridge . ‘ 35
21.—Water-eourse carried over railway in open conduit . : . 35
22.—Stream and road carried over railway on one bridge . é . 35
23.—Contract—general plan . : : : . 38
24.—Contract—longitudinal section : 38
25.—Contract—cross sections 41
26.—Fixing slope stakes : . 3 ; . : . 42
27.—Area of cross section : é ° ; : 43
28.—Working longitudinal section p s 2 45
29.—Soft cutting overlying rock . a . . - 50
30.—Excavating cutting 10 to 20 ft. deep 2 3 . 52
31.—Width required by steam digger . x si 2 . . 53
32.—Leaving wings on gullet 2 é ‘ 2 i 5 . 53
33.—Cutting into slope 3 : : » 54
34.—Arrangement in cubine —thtes iitiee of ratbeaiy 3 ‘ . 55
35.—Arrangement in cutting—two lines of railway ‘ 56
36.—Arrangement at embankment end . : j . 57
37.—Method of expediting emptying wagons . 4 ‘ é . 658

xi
xil LIST OF ILLUSTRATIONS

FIG,

38.—Excavating rock

39.—Example of railway autting ( 1)

40.—Example of railway cutting (2)

41.—Example of railway cutting (3)

42.—Cross section of railway through bog land
43.—Section of railway approaching bog

44.—Widening of railway—single to double line
45.—Widening of railway—two lines to four lines
46.—Excavating rock by “ plug and feather ”
47.—Ruston steam crane navvy

48.—Ruston steam crane navvy

49.—Wilson steam crane navvy

50.—Wilson steam crane navvy (with bent jib)
51.—Ruston steam shovel

52.—Lubecker land dredger .

53.—Ingersoll-Rand rock drill

54.—Hand hammer drill

55.—Iron tip wagon :

56.—End and side tip wagons ‘
57.—Drain for intercepting field drains id setone water
58.—Slope drains in cutting

59.—Large slope drains with toe wall at foot di dle
60.—Drystone dwarf wall at foot of slope

61.—Flat slope in loose rock cutting

62.—Face wall in rock cutting

63.—Retaining wall in soft rock cutting

64.—Slip of small dimensions in cutting

65.—Slip of large dimensions in cutting .

66.—Slip in cutting requiring special treatment
67.—Section in cutting with large volume of subsoil water
68.—Slip in embankment on side-lying ground
69.—Intercepting subsoil water under embankment
70.—Cross sections of British permanent way .

71.—Part cross section of Pennsylvania railroad, America
72.—Form of cost statement for earthwork undertakings .

73.—Detailed statement of cost and output of railway cutting .

74.—Diagram of cost and output of railway cutting ei

PAGE

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137
EARTHWORK IN RAILWAY
ENGINEERING

CHAPTER I

PRELIMINARY INVESTIGATIONS AND ESTIMATES
OF COST

THE location of a railway is for the most part governed by geo-
graphical considerations, but the promoters of the undertaking
will look more to the proposal from a financial point of view, and
in their deliberations they will be guided by the Engineer as to the
practicability and probable cost of the work.

Various proposals will no doubt have to be examined before the
scheme which is to be carried out is decided upon, and, in view of
the importance attached to the Engineer’s report, it is essential
that he be thoroughly informed in all matters which may influence
the decision of his clients.

While none of the proposals which are considered may be
altogether impracticable, yet the carrying out of the project may
only be done at a loss. It is impossible to foresee all the difficulties
that may be met with during the progress of a particular work,
but these may be very considerably reduced by more particular
examination of the details of the project by the Engineer when the
scheme is being developed.

It has been truly said that ‘“‘ It is much easier to make an expen-
sive railway than a cheap one under the same circumstances, and
the object of every Engineer ought to be as far as possible to
adapt the work he has to design to the results to be obtained.” In
a through main line of railway, heavy works such as tunnels and
large bridges will in all probability require to be executed in order
that the curves may be as easy as possible, and steep gradients

E.R.E.—B
2 EARTHWORK IN RAILWAY ENGINEERING

avoided, and large expenditure may be justifiable, whereas, in the
case of branch or secondary lines, the Engineer may have to be
content with steeper gradients and sharper curves if he is to keep
the cost within moderate limits. Consideration of each different
project must, however, be governed by the particular circum-
stances of the case. What may be an economically constructed
railway in one place, may be a wasteful expenditure in another.

Questions relating to location which are affected by trafic
working do not fall to be considered here, and the preliminary
investigations which are referred to deal with matters affecting the
actual execution of the work.

The estimated cost of the works which the Engineer prepares
should represent to a nearness what the ultimate expenditure will be.

The first cost of a railway may be reduced by making a detour,
but, on the other hand, the annual outlay in maintenance or work-
ing of the railway may be increased in consequence of the additional
length to such an extent that no real saving will be effected.
The expediency of making a diversion may arise from a desire to
avoid interference with valuable property, or to save the expense
of the construction of a large bridge, tunnel, river diversion, or
other important work, or it may be that the materials likely to
be met with in the cuttings or under the site of the embankments
are of a treacherous character, or the cost of the earthwork may be
excessive. These, and other circumstances, may have so added to
the initial estimated cost of the shorter route as to make a diversion
imperative, and it should be further noted that the more heavy
the description of the work the greater generally is the after cost
of maintenance.

When considering whether the works should be constructed for

 

 

Fie. 1.—Cutting for single line.

a single or double line of railway or of a greater width, it should be
kept in view that the cost of the earthwork is not proportionate
to the number of lines of railway.
PRELIMINARY INVESTIGATIONS AND ESTIMATES 3

Referring to Figs. 1 and 2 the areas of sections for a cutting
20 ft. deep and with the usual side slopes for soft material are for
single and double lines 980 square feet and 1200 square feet respec-
tively, the increase of the double over the single line section being

 

 

Fic. 2.—Cutting for double line.

about 22} per cent. This increase is represented in Fig. 3 by a
vertical strip 11 ft. wide, and roughly indicates the increased cost of
the earthwork with cuttings and embankments of an average depth
of 20 ft. for a double line of railway over a single line of rail-
way. The excavations for the greater width would cost a little

 

Fic. 3.—Difference between cutting for single and double lines.

less per unit of volume on account of the service roads and
other temporary works and plant required during construction
not being proportionately increased, and also on account of there
being greater facilities for carrying on the operations, but for all
practical purposes the same unit rate may be used in preparing the
preliminary estimates of cost.

If there is a likelihood. of the railway being widened at some
future time it may be advantageous to acquire land for the wider
line to begin with, although the construction of the wider line
may be deferred to a future date.

In the construction of the partial scheme the quantity of
materials in the cuttings may be in excess of the quantity
required to form the embankments, and the surplus excavated
material should be deposited in the embankments for the ultimate
4 EARTHWORK IN RAILWAY ENGINEERING

widening, or for station yards which may be contemplated in the
future, if these are conveniently situated to the cuttings.

In fixing the width of formation regard must be had to the future
maintenance of the railway. The additional cost of constructing
cuttings and embankments a foot or two wider so as to obtain
better drainage in cuttings and greater solidity in embankments is
small compared with the extra periodical expenditure in main-
tenance incurred by the construction width being restricted. By
increasing the width of a double line cutting 20 ft. deep and in
ordinary soft material from 28 ft. to 30 ft., the quantity of ex-
cavations is increased by only 34 per cent. The advantage of
having sufficient width of formation is referred to in Chapter VII,
page 130.

Consideration must also be given to the curves and gradients
of a railway. With a diverted or longer route, better gradients may
be obtained than with the direct route, but with the latter there
will probably be a better alignment. These matters will require
to be considered from a traffic working point of view before the
route is finally decided upon.

In settled countries there is not the same opportunity for
railways being made on constructionally economic lines on account
of the proximity of valuable land and property, but in undeveloped
countries where land is either given free or is comparatively cheap
considerable attention is now being paid to the question of
economics in construction which will undoubtedly effect large
savings in carrying out the undertaking and also give a better
return for the capital expended.

In laying out the line of a railway or road, endeavour should be
made to reduce the quantity of earthwork to a minimum, and the
formation level should, consistently with other considerations, be
fixed so that the quantity of suitable material excavated from
the cuttings will just be sufficient to form the embankments. It
must be kept in view that all unsuitable materials should be run
to spoil and allowance also requires to be made for the quantity of
excavations which may be used for constructional purposes. It is
a considerable advantage to have the “lead” (haul) to embank-
ment on a down grade and as short as possible.

The cost of the work, as will hereafter be shown, is largely
dependent upon the relative positions of cuttings and embankments.
PRELIMINARY INVESTIGATIONS AND ESTIMATES 5

Under certain conditions it may be advantageous to run some
of the materials which are quite suitable for embanking purposes
to spoil embankment rather than run them for a considerable
distance on an up grade. To make up the deficit of embanking
materials thts caused, side cuttings or borrow pits may be
necessary, and while this would incur the additional cost of
excavation it may be a cheaper method to adopt. Where
furnace ashes can be obtained in large quantities and at little cost
no better material could be obtained for making an embankment
and the work of depositing them can be carried on very speedily.
An embankment constructed of ashes will also entail a minimum of
expense in subsequent maintenance.

The site of a spoil bank should be convenient to the excava-
tions and have an easy access with a minimum of expenditure for
wayleave, use of ground, subsequent restoration and for depositing
the material. A mistake may be made by using moss land or
other similar site where the ground can be cheaply obtained, as there
may be considerable expense incurred in making up and constantly
repairing service roads while the material is being deposited.

The simplest construction for a railway might appear to be where
the work is executed on side-lying ground, partly in cutting and
partly in embankment, and with just sufficient material in the
cutting to form the embankment. If the material excavated is of
an earthy description and can be removed without any slipping on
the upper side taking place the conditions would be favourable,
but if, on the other hand, there is a tendency for the ground to
slip by reason of the support which formerly existed having been
removed, the work may be very costly to execute. This matter
is fully considered in subsequent reference to slips.

In skirting hillsides it is frequently found that the natural slope
of the soft material overlying rock is inclined at the angle of repose
of the material, and it is thus desirable under these conditions to
have as little cutting as possible. The material necessary for
embanking purposes could then be obtained either from adjoining
cuttings where the surface was at such an angle as to prevent slips
or it could be got from borrow pits. In the latter contingency the
extra cost of side cutting would be incurred, but this course may
ultimately prove to be the more economical form of construction.

A usual practice in countries where there are severe snowstorms is
6 EARTHWORK IN RAILWAY ENGINEERING

to dispense with cuttings almost entirely and thus avoid obstruction
to traffic by snow blocks, the banks being made up by material
taken from borrow pits. Apart from the question of snow blocks
a railway on embankment is less costly to maintain.

The side ditches in a cutting require to be kept clear of materials
washed off the slopes or which may have collected, and which if
not removed will tend to keep the formation of the railway in a
wet sodden condition, to the detriment of the permanent way.

In countries where timber is plentiful, ravines necessitating what
would be long high embankments may be temporarily spanned by
trestle-work so ag to speedily complete the line of communication,
and at a later date the embanking materials would be deposited.

Again, by following closely the line of a water-course the presence
of moss, clay, or other soft material may be the cause of serious
trouble, either in a cutting or in an embankment, and therefore
the possibility of more material being excavated or more material
being required for embankment than originally anticipated should
not be overlooked when locating the proposed works.

In rough hilly country, where there may be a large exposed
surface of loose friable rock and boulders, the streams will, after
frost and during torrential rain, carry in their course a considerable
quantity of stones down the hillside which will be deposited on the
plain below.

If the railway were constructed on the flat land at the foot of
the hill, any water openings would then be liable to be choked up,
and the railway should, therefore, be constructed on the hillside
where the velocity of the water is still great enough to carry the
stones through the water openings.

Further, the water-courses which are confined to narrow channels
on the hillside will open out and spread over a wide area on the flat
ground, which in flood-time will thus be under water, and if the
railway were constructed on the low ground considerable damage
might result before the water passed through the flood openings
in the railway embankment. Reference to allowing flood water to
pass entirely over low railway embankments is made in Chapter ITI,
page 21.

The cost of the undertaking will largely depend on the character
of the materials met with during construction, and it is necessary
that the fullest information be ascertained in regard to the strata.
PRELIMINARY INVESTIGATIONS AND ESTIMATES 7

For the purpose of the preliminary estimates, this information will
have to be obtained from general observations of the surrounding
country, and from geological maps of the district, if these are
procurable. In the absence of actual bores or trial pits on the site
of the works, the depth of soft material overlying rock and the
characteristics of that material would be more or less indefinite,
but after such arrangements have been made as will allow of a
complete series of bores being taken or trial pits sunk, the fullest
particulars should be obtained.

The cost of obtaining information in regard to the strata is so
small in comparison with the results obtained that in work of any
magnitude the question of expense should be a secondary con-
sideration.

The extent of land necessary for both cuttings and embankments
is dependent upon the character of the materials in the cuttings
and under the sites of the embankments. If the works are being
constructed through or in the vicinity of valuable property retaining
walls may be required to support the sides of a cutting, or reduce
the area of land covered by embankment, and the cost of these
contingent works has also to be estimated.

The Engineer must keep in view the possibility of the materials
requiring flatter slopes than would at first sight appear necessary
and the probability of retaining walls having to be provided to
retain the slopes within the land acquired or the necessity of more
land being required than was originally contemplated. If more
land has to be bought after the works are commenced a larger rate
will most likely have to be paid for it. If these matters are lightly
passed over the original estimates will in all likelihood be largely
exceeded when the works are completed.

In the initial stages of an undertaking it is generally necessary
that secrecy be observed, and, in view of this fact, and also on
account of the short time usually allotted for the preparation of
preliminary enquiries, the estimates of cost may be of a somewhat
incomplete description. An exact section of the ground may not
be available, but sufficient information can generally be obtained
from “ spot” levels of the more prominent points, and by making
full use of the levels and contour lines which are laid down on
Ordnance Survey maps. For the purpose of calculating the quan-
tities of earthwork and for ascertaining the boundaries of the land.
8 EARTHWORK IN RAILWAY ENGINEERING

required typical cross sections should be prepared, and in open
country these might be at intervals of from three to five chains
apart.

In view of the approximate description of the preliminary esti-
mates an ample allowance—say 10 to 15 per cent of the whole—
should be added to the cost for possible contingencies, so that the
total sum will prove adequate for the execution of the proposed
work. It is better that this estimate should be over rather than
under the actual cost of the undertaking, so that the promoters of
the scheme will not be misled, but unfortunately it too frequently
occurs that preliminary estimates are considerably understated.

Where estimates of costs are subjected to the criticism
of rival Engineers or Parliamentary Committees, and when the
various details on which the figures are based are subjected to the
closest scrutiny, it is most desirable that the assumptions both as
regards quantities and rates should be well founded.

After Parliamentary sanction has been obtained or agreements
have been made with the proprietors of the land on which the pro-
posed works are situated, complete longitudinal and cross sections
of the ground should be taken and a thorough investigation made
of the strata so that the exact line of the railway may be determined
and a fully revised estimate of cost prepared. The quantities of
the materials of this new estimate will form the basis for the subse-
quent Contract Schedule and these should be as full and complete
as possible. Special consideration should be given to the unit
prices for each item of work. The probability of an increase of the
cost of labour or materials during the period of construction and
the possibility of interruption by reason of wet weather and conse-
quent loss should also be kept in view.

The magnitude of the work will also influence the unit cost. In
works of small dimensions on which it would be unprofitable to
place large and expensive plant the cost would be proportionately
more than where mechanical excavators, etc., can be advan-
tageously used. The more complete the information is that affects
the quantities or prices the nearer will be the amount of the
Contract Tender to the actual cost of the work, in which case the
result will be more satisfactory to both contracting parties.
CHAPTER II
INVESTIGATION AS TO STRATA

In earthwork undertakings the principal matter that affects the
quantities and prices in the Detailed Estimate on which the Con-
tract Tender is based, is the character of the strata under the site
of the works,

It is thus of the first importance that definite and reliable informa-
tion be obtained in regard to the characteristics of the materials
in the strata. The presence of water and the effect of it on the
various classes of materials met with have an important bearing
on the success of the undertaking, and particulars relative thereto
should receive special attention.

For the purpose of ascertaining the character of the strata it is
usual to put down bores along the line of the railway or over the
site of the works.

Some Engineers consider that trial pits should be sunk, so as to
get more complete information than is obtainable from bores.

By the particulars so obtained the slopes for the cuttings are
decided on and the quantities for the Contract Schedule calculated.

The slopes in a cutting of ordinary material may vary from 1
horizontal to 1 vertical, to 2 horizontal to 1 vertical, while in a
rock cutting from a plumb face to $ horizontal to 1 vertical, depend-
ing on the character of the tinier the quantity of water met
with, the effect of water or atmospheric conditions on the material
when exposed, and the slope or “dip” of the strata.

A description of the materials on the sites of the embankments
is also essential for the purpose of ascertaining the bearing capacity,
and fixing the quantity of material required for the embankments.

If in carrying out the work there should be any great divergence
in the actual quantities of materials in the cuttings from what was
stated in the Contract Schedule the method of procedure may

have to be modified.
9
10 EARTHWORK IN RAILWAY ENGINEERING

As example, a cutting may contain considerably more rock than
was at first anticipated, and on account of this it may be necessary
to construct overland routes for the purpose of passing the material
from other cuttings to embankments, and thus allow the oper-
ations in the soft cutting to be proceeded with at the same time
as in the rock cutting, or other special means may require to be
adopted so that the work may be executed within a reasonable time.

The fact of having an increased quantity of rock to excavate
increases both the cost of the work and the time of completion and
if definite information in regard to the strata had been forthcoming
previous to the work having been commenced the Engineer might
have considered a diversion of the route of the railway, or the
promoters might have decided to abandon the project.

When executing the widening of an existing railway it may seem
sufficient to form an opinion as to the character of the materials in
cuttings from the appearance of the existing cuttings.

In the case of solid rock cutting no mistake may arise, but in the
case of the ordinary soft material or materials of a “ faikey’’*
character where the action of the weather may have very materially
altered the adhesion of the particles or the surfaces to one
another, it is not safe to rely too much on what is seen of the
existing cuttings.

In a case which recently came under the author’s notice the
slope of the original cutting had a batter of 14 horizontal to 1
vertical, and to all appearance the cutting was of a clayey descrip-
tion. On executing the work, however, the material met with con-
sisted of close-bound gravel held together by hard clay, and was of
such a character that it was quite impossible to remove it by pick
and shovel. On account of the situation it was not possible to use
a steam digger, and it was necessary to break up the material by
blasting throughout the whole period of the operations. After
the material had been exposed to wet weather the clay lost all its
cohesion and the slopes had to be dressed to the batter for an
ordinary soft cutting. At several places in the slopes minor slips
took place on account of the “weathering” of the material.

In another instance of railway widening a number of large pieces
of rock protruded from the slope of the existing cutting, which
gave every indication of rock being met with, but on the work

* Similar in character to laminated shale.
INVESTIGATION AS TO STRATA ll

being carried out it was found that no solid rock existed and that
a large number of loose stones were embedded in the slopes of the
old cutting, so that the appearance of the original cutting was
deceptive in respect of the actual condition of matters.

In general practice boring is carried out by means of a chisel,
samples of the material passed through being brought to the surface
for inspection at intervals as the sinking operations proceed. Where
more accurate information is required diamond drilling is adopted,
in which case a solid core of the material passed through is
obtained.

By sinking pits the most reliable data as to the actual state of
matters will be obtained, but the time taken in sinking pits of any
great depth will, in most cases, be against this mode of procedure.

Chisel boring is a very simple operation, and when the work is
in the hands of a thoroughly skilled and trustworthy borer very
satisfactory results are obtained.

In chisel boring, owing to the importance of the information
required, the work should be carried out by a reputable firm of
borers under the direct supervision of the Engineer, who should
keep himself fully conversant with the progress of the operations,
and have repeated checks made of the depths of the strata entirely
independent of the journal with which the borer afterwards furnishes
him. He should also verify the depth of each bore immediately after
it has been put down to the required depth. The borer should lay
out for inspection samples of all the various strata passed through.
By adopting such means the information so obtained will be as
accurate as is possible by this method.

It is unnecessary to describe in detail the whole procedure of
chisel boring, and only a brief reference to the tools and the manner
of use will be made. The bore hole is formed by repeated blows
from a chisel (c) which is raised and lowered by manual labour (see
Fig. 4). The tool is turned round in the hole a quarter of a circle
after each stroke is made so that no two blows fall in succession
on the same spot, and the material, after being thoroughly
bruised, is brought to the surface by means of a “sludge”
pump (f). ;

In passing through ordinary soil, sand, clay without stones,
or similar material the sharp edge of the tube of the pump
is sufficient to pierce the strata, but where gravel, boulders, or
12 EARTHWORK IN RAILWAY ENGINEERING
rock are met with the chisel is required. Where the material is

exceptionally hard the cross-shaped piece, or “ riffle”’ tool (e), is
used.

The cutting tool is connected with the cross-head on the
working platform by means of l-in. square section rods, which

<o
xs Level ll

ea
)
(f)
ko 5"
(e)
I
s C3

(6) |

    

Platform

2

 

Fia. 4.—Chisel boring.

are generally in lengths of 5 ft. and screwed together as shown ;
shorter lengths being used when each of the 5-ft. lengths has
brought the cross-head down to the level of the working platform.
The platform should be at a height of about 5 or 6 ft. above the
ground so as to allow of tubing being inserted into the bore holes
INVESTIGATION AS TO STRATA 13

when passing through soft ground and where the sides of the hole
would have a tendency to fall in unless properly supported, in which
case an inaccurate record would be obtained. It is necessary that
the tube should closely follow the cutting tool as the work proceeds.
Of course, in rock no tube lining is necessary.

If the strata should be dry it is essential that water be poured
down the tube for the purpose of converting the material into a
consistency of slurry and thus allow of it being removed by the
“sludge” pump. In order that a correct record may be obtained
samples of the strata should be brought to the surface at least
every 2 ft. of depth.

All depths should be measured from the level of the working
platform, the height of which above the level of a wooden peg or
mark on the ground level should be known before boring opera-
tions are commenced. The level of the peg or mark should be
connected with Ordnance Survey level or the same datum to
which the sections for the railway have been taken, so that after
the journal of bores has been completed the information obtained
can be laid down on the sections of the ground surface.
Three or four men are usually employed in sinking the bore,
one of them being a practical borer who would be responsible for
the preparation of the record. While the contents of the “sludge”
pump indicate the character of the material passed through, the
borer puts considerable reliance on the “feel” on the cross-
head.

When boulders are met with, if the boring tool comes down fair
on the top of the stone, there will be no difficulty in passing through
it, but if the tool strikes the smooth rounded surface away from
the top, the stone will yield in the surrounding clay and it will
be next to impossible to pierce it. In such case a small charge of
dynamite should be inserted in the bore and the boulder shattered.
Lf this is not effective it will be necessary to abandon the bore and
sink another a short distance away.

All the bruised material, whether hard or soft, is brought to the
surface in the same wet condition, and it is only by the “ feel”
when sinking and the rate of progress that the relative hardness
of the material is ascertained. It is necessary that the pump be
put down at every 2 ft., and more frequently if necessary, if a change
of stratum is suspected by the “feel” on the cross-head. It will
14 EARTHWORK IN RAILWAY ENGINEERING

be recognized that the borer, in addition to having a thorough
practical knowledge of his business, must exercise considerable
care in systematically noting the various changes of material if
the results obtained are to be of any real practical value.

A very common error, and one which has frequently been the
cause of much litigation, is to mistake a boulder in a “ soft”
stratum for solid rock. The effect of this may be very serious. In
the case of a railway or road cutting, by assuming that rock has
been reached when only a boulder has been struck the quantity of
material which it is anticipated has to be excavated may, as already
stated, be considerably in excess of the actual quantity to be
removed and this may have serious consequences.

When rock is met with, before it is recorded as solid rock, the
thickness passed through should exceed 5 ft. If this depth is ex-
ceeded it is pretty safe to assume that a bed of rock has been
passed through, but if not, a new bore 6 or 8 ft. distant should be
put down as a check, and if the strata is repeated it is evident
that a layer of rock exists. The depth of a bore hole should never
be less than 5 ft. below the bottom of the proposed excavations,
whether in “soft” or in “ rock,” so that the fullest information
may be obtained of the material to be excavated and also of the
character of the strata below formation level of the railway on which
it is proposed to support the foundations of structures.

Hard-bound gravel can be easily distinguished from loose gravel
and the various degrees of hardness of faikes and limestone can
also be easily recognized, and where water is in a strata its presence
can be detected. The volume of this water—a point which is of
very great importance when carrying out constructional work—
cannot, however, be computed by boring.

As regards diamond boring, this method is now generally adopted
where it is of advantage to have a solid core of rock, such as in
mineral prospecting, and in locating the site of a reservoir embank-
ment, where it is of great importance to know the character of the
stratification below the submerged area. In the case of tunnel
work, or where heavy foundations are in rock, the results obtained
from diamond boring would be preferable to those obtained by
chisel boring. The result of the bore cannot be questioned when a
solid core of rock can be seen, and the consequent risk of error in
judgment on the part of the borer is thereby eliminated.
INVESTIGATION AS TO STRATA 15

In diamond boring the material is cut through by abrasion
instead of by percussion, as is the case in chisel boring.
The cutting tool or “ crown” consists of a mild steel cylinder

on the lower surface of which carbonados
(imperfectly crystallized diamonds) are
studded at intervals (see Fig. 5). When
the bore is being taken for mineral pros-
pecting or for the purpose of ascertaining
the character of the strata for earthwork
operations the core of rock need not be
more than 2 or 3 in. in diameter. The
“crown” piece would be about } in.
thick and a set of twelve diamonds is
distributed over the lower, outer, and
inner surfaces, as shown on the diagram,
so that the bore hole which is formed will
be slightly greater in diameter than the
cylinder in which the diamonds are set,
and the core of rock which is cut out will
be slightly less in diameter than the
internal surface of the cylinder. The
diamonds are so arranged that the ring
of material cut through between the
outer and inner edges of the cylinder
will be entirely crushed.

The core, after being cut, passes up
through the “crown” cylinder into the
core tube, which is about 6 ft. long and
which is screwed on to the upper end
of the cylinder. This tube in turn is
attached to hollow iron rods of convenient
length which extend to the surface of the
ground. The tool is caused to revolve
either by hand labour or by being con-
nected to a stationary engine.

It is necessary while the boring oper-

 

Fic. 5.—‘“ Crown”? of
diamond drill.

ations are in progress that a constant and ample supply of water
be forced down the hollow rod and through the core tube so that
the crushed material under the cutting edge will be immediately
16 EARTHWORK IN RAILWAY ENGINEERING

washed out, the water rising up the outside of the core tube and
flowing over the bore hole. The water also assists in keeping the
cutting tool cool. The tool is caused to revolve at a speed of
from 60 to 100 revolutions per minute, depending on the character
of the materials passed through.

It is most important that the crushed material under the cutting
edge be instantly removed, as otherwise the metal in which the
diamonds are fixed will become worn and the diamonds will drop
out. The pressure on the rock under the cutting edge should be
relieved as the work progresses by having a back balance seer
fixed to a cross-head at the surface.

While diamond boring gives the true character and exact thick-
ness of the various beds of rock passed through, it is not possible
to say in which direction the rock is dipping, but by taking a series
of bores a correct geological section can be prepared.

TRIAL PITS

Trial pits would be 5 or 6 ft. square. If the excavations are soft
material it would, unless the pits are comparatively shallow, be
necessary to close timber the sides of the openings. If the stratum
is rock, timbering would not be necessary. Operations would be
retarded if water were met with, and if it should be of considerable
volume it may be impossible to proceed with the work. In bad
ground or where there is a large volume of water iron cylinders,
consisting of built segmental sections with flange joints, would be
used.

While the time occupied in sinking trial shafts is considerably
more than that taken by putting down bores, the information
obtained gives a more correct indication of the strata passed
through. Trial shafts at intervals supplemented by a series of
bores to ascertain the levels of the various beds and thereby find
out if there is any exceptional variation in the strata would provide
a full knowledge of the geological conditions.

Trial shafts or bores are of no practical value unless they are
carried down to the full depth of the proposed excavations, or, in
the case of foundation work, to the depth of a solid stratum.

As regards the rate of progress in boring, the following figures
give a rough approximation :—
INVESTIGATION: AS TO STRATA 17

WITH HAND CHISEL BORING

Fine sand or clay without stones . ‘ . 50 ft. in 8 hrs.
Boulder clay or open gravel . j : a te. as
Close-bound gravel. : ‘ ‘ 6to8ft. ,,
Soft sandstone . ‘ ; ; . S8tol2it. ,,
Hard sandstone . : . ; ‘ 2to4ft. ,,
Extra hard sandstone . ; : : « bits:
WITH DIAMOND BORING
Hard sandstone . ; ; i ‘ . lot. ,,
Extra hard sandstone . : ; ; . oft. ,,

When hard whin boulders are met with in boulder clay it is no
uncommon thing for only a few inches to be pierced by chisel
boring in a day’s work.

While the chisel is the tool generally in use for boring in this
country, the ‘“‘ wash-out” drill, which, as the name implies, con-
sists of the material being washed out by water under pressure,
is largely used in America. The record so obtained in passing
through soft material is not considered very satisfactory, but the
advantage in using this system is the rapidity in clearing a way
for a diamond drill being used in the rock underneath.

In describing the strata passed through a Borer should refrain
from making use of any local expression which may be ambiguous
or misleading, and the Engineer, when preparing the journals which
are to be shown to, and will be made use of by, the Contractor,
should make certain that the description which he gives is in
general terms and correctly sets forth the class of material so that
no subsequent misunderstanding may arise as to the character of
the materials in the bore.

While it may not be absolutely necessary for a Borer or an
Engineer to have a knowledge of geology there is no gaimsaying
the fact that only by a thorough appreciation of the characteristics
of the materials generally met with and their relative positions
to one another in the strata, together with the conditions under
which they have originally been deposited, can he form a correct
opinion of the materials he is dealing with.

E.R,E.—0O
CHAPTER III
CULVERTS AND DRAINAGE

THE situation of a line of railway, relative to rivers and principal
waterways, is an important consideration in determining the
location of the proposed works. The larger rivers and waterways
would be crossed by means of bridges or viaducts, and do not
come under the present investigation.

In crossing streams or water-courses of less magnitude the pro-
vision which requires to be made must receive due consideration
in designing and carrying out the works. Local deviations of the
line of the railway may suggest themselves with a view to less
costly, while equally efficient, conduits or culverts being constructed
without materially affecting the cost of the earthwork or other
works. These may result in a shorter length of waterway or in a
more solid foundation being obtained, or what is of considerable
importance during construction, a line may be got which will allow
of the greater part of the operations in constructing the waterway
being executed with a minimum of interference with the original
water-course, and thereby in comparatively dry ground.

By taking the water channel whether in tunnel or open-cut
through a spur of rock the excavations may be more costly to exe-
cute, but by reason of a shorter length of channel being obtained
less masonry will be required for facing the excavations and in
constructing the arch and invert, and the total cost may thereby
be considerably reduced.

It is of the utmost importance when making a railway that all
work connected with the construction of culverts or waterways, or
the drainage of the adjoining lands, be entirely completed before
the earthworks in the vicinity are proceeded with, so that slips,
by reason of water flowing through the strata into the cuttings or
under the site of the embankments, may be reduced to a minimum.

The capacity of a culvert or waterway should be such as will

18
CULVERTS AND DRAINAGE 19

allow of the free passage of water during the period of maximum
rainfall. Careful observations should be taken of the flow in the
stream during wet seasons and flood-times and information should
also be obtained from old residents in the district. By comparing
these particulars with records of rainfall taken during previous
years, if such are available, an approximate idea of what may be
expected will be obtained. Where there are existing culverts or
bridges on the streams which are being dealt with the effect of the
flow of water on these and their capacity to deal with the quantity
of water passing through them should be noted.

Apart from any information so obtained it is desirable that the
size of the culvert required to carry important streams under the
railway should be ascertained by calculation. The determining
factors are, the maximum rainfall in the district, the area of the
water-shed, the slope of the ground from which the water dis-
charges, the porosity of the soil, and the condition of the stream
or river bed. Various formule are in use, but it will be recognized
that the local conditions referred to make a universal application
of a formula for the “ run-off” impracticable.

There will be a much greater discharge from an area with steep
sides than from a flat basin. The more impervious the surface of
the ground is the greater will be the discharge, but it should be
borne in mind that some soils will be rendered impervious after
a few hours’ heavy rain, at the end of which time the soil may be
said to be water-logged. A wet marshy ground might be described
as water-logged and will yield a large “run-off” in a heavy rain-
storm.

A good formula for ascertaining the discharge from catchment
areas, given in Parker’s “ Control of Water,” is :—

Q=640 F.I.M.}
Where :—

Q=discharge in cubic feet per second. ;
I=Average intensity of max. rainfall in inches per hour during a
period of time equal to that taken by the flood water to reach
the culvert from the farthest point of the drainage area.
M=Area of catchment area in square miles.

F is a coefficient depending on the character of the surface as follows :—

For flat country, sandy soil, or cultivated land, 0°25 to 0°35.
For meadows and gentle slopes, 0°35 to 0°45.

1 This formula is sometimes given: Q=640 F J) M.
20 EARTHWORK IN RAILWAY ENGINEERING

For wooded hills and compact or stony ground, 0°45 to 0°55. :
For mountainous or rocky ground, or non-absorbent (e.g. frozen soil) sur-
faces, 0°55 to 0°65.

Apart from the results obtained by the use of a formula an ample
margin should be provided for extraordinary floods. Some Engineers
double the result obtained by a formula, and in view of the damage
which may result from having a restricted waterway and the small
increased expenditure incurred in providing the larger culverts as
compared with the cost of the whole railway undertaking this
seems a proper course to adopt.

The late Dr. Deacon, when investigating the rainfall in the Welsh
mountains in connection with the Liverpool water supply, ascer-
tained that the maximum discharge of tributary streams commonly
reached 1000 times the dry weather flow, and occasionally in-
dividual streams very much exceeded that figure. In the Vymwy
River, even after passing over from four to five miles of alluvial
deposit, the maximum discharge recorded as much as 800 times
the dry-weather flow of the river, and the records obtained from
rain gauges which were within a few miles of one another showed a
very considerable variation in rainfall.

It is thus most important that information regarding the flow
of water in streams should be localized as much as possible, and’
that the capacity of the culvert should equal the discharge from
extraordinary floods. The probability of there being excessive
flooding by reason of melting snow should be specially noted.

Allowance should be made in designing culverts for the possi-
bility of the effective sectional area being reduced by becoming
silted up. This will be greater if the stream has a flat gradient, as
under ordinary circumstances the flow in it will be sluggish.

In new countries where records of rainfall are not obtainable it is
usual to construct temporary timber bridges or rail openings which
are in use for a few years until it is seen what provision requires to
be made in constructing the permanent culverts.

In hilly country a large quantity of embanking material is
generally lost on account of sudden and heavy floods before it is
possible to judge what size of openings should be provided, and the
embankment on each side of these water openings should be well
protected by having stone pitching carried up the slopes as high
as the probable flood level.
CULVERTS AND DRAINAGE 21

Where there are wide depressions of land in countries subject to
heavy rainstorms, over which during the period of floods a large
area of flood water flows, it is usual, provided the water is shallow,
to let it pass over the line altogether (see Fig. 6). This is effected

 

w---~Lortion of Embankment pitched ;
5 re dighes: Huot ===> i

     
     
    
 
 

Flood openings
Longitudinal Section of Railway

 

 

Cross Section of Railway shewing
Pitching of Embankment
Fia. 6.—Water openings in embankments.

by forming the line on each side of the depression with an easy
grade down to a level portion, which level portion might extend
to from 100 to 400 ft. in length, as shown in the diagram. For the
purpose of protecting the railway and the slopes on each side and
between the sleepers, the surface would be covered with stone
pitching which would extend for the whole length of the level
portion and up the gradients to a level clear of flood level.

DESIGN OF CULVERTS OR WATER-COURSES

It is of the utmost importance that the construction of culverts
and water-courses, where they pass under embankments, should
be of a most substantial description in view of the expense and
inconvenience incurred in opening up embankments for the purpose
of executing remedial work.

Existing conduits on the site of the embankment should be
strengthened or reconstructed. When pipes are used for the pur-
pose of carrying the stream, they should preferably be of iron or
steel, and if they are not laid on solid ground they should be sup-
ported on masonry piers or piles. On account of malleable iron or
steel pipes being lighter than those of cast iron they can be made
in longer lengths and consequently fewer joints are necessary. They
are also less liable to injury than cast-iron pipes.

In soft ground or where there is a tendency to subsidence by
22 EARTHWORK IN RAILWAY ENGINEERING

reason of mineral workings malleable iron or steel pipes are prefer-
able. The smaller weight per unit of length is also a consideration
in cases where it is necessary to drag the pipes over fields or convey
them long distances over secondary roads. Malleable iron or steel
pipes, however, are more subject to corrosion than cast-iron pipes,
and care should be taken to ensure that they are properly pro-
tected by preservative coatings or by having them encased in
concrete.

Where fire-clay pipes are taken under a railway they should be

 

15'Dis' EC Pipes

Concrete
(a) (6) (c)

Fia. 7.—Fire-clay pipe drains under railway.

‘Dia’ ECPip

10)

Concrete

 
     

  

 

 

 

 

encased in concrete (see Fig. 7). When concreting materials can
be economically obtained a fire-clay pipe conduit is in many cases
adopted in preference to cast iron, more especially in the smaller
diameter of pipes.

In conveying water from one side of a railway embankment to
another when crossing bog-land, timber box drains are generally

ax

Bolts
12x3

     
  
 
 

    
   

(2x3 4
Cross Section Longitudinal Section.
Fic. 8.—Timber box drain under railway.

for——_— 9° 0 —

 

used (see Fig. 8). While these may be considered to be more of a
temporary character, if they are constructed of creosoted pitch-pine
timber they will last for a number of years, and in the particular
situation where they would be used they are easily accessible when
they require to be repaired or renewed.

For conduits of a less size than 2 ft. 6 in. square, and where pipes
cannot be conveniently used, built stone drains are constructed
CULVERTS AND DRAINAGE 23

(see Fig. 9). These consist of a floor of concrete with masonry walls
built with cement and covered over with a slab or paving stone.
The cover stones should be well bedded on the top of the side walls

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stone Slab: he
Paving Stone [Ss T
Stone a! *o
toa ge co ss N;
6k Fok 2: —L | el 9 hee 26 ood: =
| Concrete iS | Conarete Ss
(a) (4)
al
=
# ‘oa i@ Tn ‘ sy} on
Bk 16 —e 2-0 ake (6 te 2°0 bake 16 9
Ee
Se

 

(c)

Fia. 9.—Built stone drains under railway.

and close jointed with cement mortar in order to prevent banking

material finding its way into the culvert.
When the volume of water in a stream is greater than a 2 ft. 6in.

ro" See ee
ae

Concrete

 

 

od oon

 

 

 

 

 

 

 

 

 

 

j ie 3°6 5:0
C—O pm
Concrete ar

(a) (6)

Fiq. 10.—Arch culverts under railway.

drain can carry masonry built culverts are adopted (see Fig. 10).
These generally have an arched roof and are either wholly of con-
crete or are constructed partly of concrete and partly with stone
or brickwork. The particular materials used will be governed by
24 EARTHWORK IN RAILWAY ENGINEERING

the facilities for obtaining them. Ferro concrete construction is now
largely adopted, having either a rectangular or arched section. To
ensure satisfactory results, however, it is absolutely essential that
the materials used should be of the best description and also that
every care be taken in the making of the concrete,

Riveted malleable iron or steel tubes are sometimes substituted
for built culverts. These can be obtained up to 6 or 8 ft. in diameter,
and, being accessible for inspection and for painting or coating with
preservative solution, they may, if proper attention is paid to the
maintenance, be said to be equally as efficient as a masonry culvert.
If one line of tubing is not sufficient to carry the stream two or
more could be laid alongside one another.

   

k2°6 8

        

TE Saeston: Longitudinal Section.
Fia. 11.—Culverts with steel beams and concrete covering.

When the headway above the bed of the stream where it passes
under a railway or road is limited, the roof of the culvert could
be formed with steel beams and concrete filling between them, or
slabs of concrete with steel reinforcement could be used (see Fig. 11).
These can either be built in lengths on the solid ground alongside
and afterwards lifted into position, or the reinforced concrete can
be formed in situ by placing timber between the side walls. The
former method has the advantage that less timber is necessary, but,
on the other hand, additional lifting power is required to place the
slabs in position if they are made on the adjoining ground.

When a culvert requires to be constructed in very side-lying
ground and where there would be considerable flow the invert should
be left rough, and, in this connection, whinstone pitching is largely
used. In open channels, in addition to whinstone pitching being
used for the purpose of checking the flow, some of the pitching
stones can be set on edge at intervals and made to project above
the surface to the extent of about 6 in., the object being to further
reduce the velocity of the current.
CULVERTS AND DRAINAGE 25

A series of steps at the end of a culvert would fulfil the same
purpose, or a well or pool about 4 ft. in depth could be formed

   
   
   

intercepting Drain

 

 

 

 

 

 

 

8 I
[ 5 3 eh
3 3 ——— 2
S 8 E
[ = So = a
é ee
o ry
— {Ets

 

 

 

 

 

 

Fia, 12.—Pipe conduit under railway embankment on side-lying ground.

 

              
           
 

Coy
et
SFI

a
Sats

ee

rs
a

  

3
=n

és

= =
Ea

     

  

es

into which the water would discharge before getting into the
regular course of the stream (see Fig. 12).
When a line of pipes is laid on side-lying ground the pipes should
26 EARTHWORK IN RAILWAY ENGINEERING

be supported by small masonry piers which, in the case of cast-iron
pipes, would be placed on the lower side of the faucets, or the joints
can be encased in concrete, as shown in Fig. 12, while if malleable
iron or steel pipes are used the pipes would be held in position by
having metal straps riveted to the tubes at intervals, the ends of
the straps being embedded in concrete blocks. Any movement
in the pipes would be attended with very serious results to the
embankment overhead.

In the case of a culvert built on sloping ground the foundations
should be laid on level benches while the water-run would either
follow the grade of the side-lying ground or could be stepped, and
if the ground has a very steep slope the arch would also be built

    
   
 
    

Railway
Embankment

 

    

we

 
  

oe
A

Culvert

 
 

vee

Fra. 13.—Stepped arch culvert on side-lying ground.

in level sections (see Fig. 13). The level crown, while allowing of
level beds being formed in the masonry, would also act as a support
to, and prevent slipping of the embankment.

Where culverts are constructed on soft ground they should be
carried on piles and built in lengths of from 20 to 30 ft., each length
being entirely disconnected from the adjoining one except for a
cement joint, the idea being that in the event of unequal subsidence
taking place by reason of the weight of the embankment on the top,
the culvert will not be subjected to the same risk of damage. In the
event of subsidence taking place the joints between the various
lengths can be made good. Even in good ground—except solid
rock—it is well to build the culvert in sections when under
high embankments, as there will be subsidence, however slight,

due to the weight of the embankment on the strata under the
culvert.
CULVERTS AND DRAINAGE 27

This suggests that culverts under high embankments should be
built with a vertical camber, as is sometimes done to allow for the
varying subsidence which may be expected from the greater weight
under the centre of the embankment. If the culvert is constructed
on the level and subsidence takes place the hollow in the centre will
become silted up and the effective water area will thereby be
reduced.

Tn fixing the line of a culvert under an embankment it is better
that it should be constructed by cutting into the sloping ground
on one side of the natural run of the stream and thus have a
smaller side surface area exposed to the pressure of the made-up
embankment, as at Section B, Fig. 15. There would also be less risk
of damage to the culvert by reason of any slipping of the material
of which the embankment is composed.

The length of culverts under high embankments should be such
as will allow of the slopes of the embanking material taking the
natural angle of repose. The invert of the water channel between
the walls at both ends should be pitched with stone, and at the
inlet end the pitching should be laid on a bed of concrete made
continuous with the concrete foundation of the inlet walls. A
concrete apron should also be formed at the inlet end for the pur-
pose of preventing the invert of the culvert being undermined by
flooding, as shown in Fig. 12.

Culverts and waterways should be protected by having a grating
placed at the upper end to prevent debris or floating branches of
trees choking the culvert and obstructing the flow. These gratings
or gates should be placed far enough back from the entrance to the
culvert as not to reduce the available area of the waterway or in
any way obstruct the free flow of water into the culvert.

Special attention should be given to the design of the ends of the
culvert in order to obtain a maximum efficiency (see Fig. 14). The
best results are obtained when the inlet has a bell mouth shape
and where the approach channel is at the same level as the invert
of the culvert. All obstruction by forming corners in the masonry
should be avoided. The most objectionable form of inlet would be
to have the walls at right angles to the line of the culvert as at (A),
Fig. 14, in which case the water entering the culvert forms an eddy,
which is a serious obstruction to the free flow. The walls at the
outlet end should be carried straight out in the line of the culvert or
28 EARTHWORK IN RAILWAY ENGINEERING

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Intet End. Elevation. Outlet End.Elevation.

ee ee

roe
mee

 

     
   

 

|

o

Inlet End. Plan. Outlet End Plan.

Yor

 

 

 

 

 

 

 

 

 

 

 

 

 

 

‘ pn

 

 

 

 

 

  

(A)

 

Level Line

 

 

A LhApron

Inlet End. Section AA.
Fira. 14.—Design of ends of culverts.

a ae

”
CULVERTS AND DRAINAGE 29

bell-mouthed the same as the inlet end so as to take the water
clear of the culvert.

Culverts should, wherever possible, be straight and have a uniform
grade throughout.

Under certain circumstances it may be possible to convey water
from two or more water-courses into one culvert and thereby
reduce the number and length of culverts under the railway or
road (see Fig. 15). Where it is necessary to take the waterway in

   

Din,
EMO OOH a0 Lisa

 

 

 

 

 

 

 

 

 

 

 

 

a
4
Ss
Sroung c&
ae
so
S
SS
Concrete
Section B

Fic. 15.—Two water-courses conveyed in one culvert under railway.

an open channel alongside a railway embankment the bottom and
sloping walls of the channel should be pitched with hand-set stones
and grouted with cement to prevent damage to the railway embank-
ment.

In constructing culverts under embankments it is a common
practice to place them in the line of the water-course at the
bottom of the valley to be crossed and consequently at the highest
and widest part of the embankment. In this situation the
culvert may be of considerable length, and the first cost of it,
30 EARTHWORK IN RAILWAY ENGINEERING

as well as the subsequent maintenance will form an important
item. Where the ground is comparatively flat there may be
no alternative, but where it is side-lying and where the
stream has a rapid fall it may be possible to divert the water-
course on the upper side of the embankment and carry it in open
cut or built culvert with very little cover along the contour of the
sloping ground and with just sufficient fall to properly carry away
the water and thereby cross the railway at a much narrower point
(see Fig. 16). By doing so the length of the portion under the rail-
way or road may be very considerably reduced and the part of the
conduit in open channel or built culvert would be easily accessible
for the purpose of repairs or for the cleaning out of debris which
might be washed down. It would, of course, be better that the
whole length of the approach conduit should be in open channel,
but this may not be possible.

If it can be arranged to have the crossing of the railway or road
at the junction of the embankment with the adjoining cutting,
the length of the covered channel would be reduced to the width
of the formation of the railway or road. The pressure on the arch
or upper surface of the culvert would also be reduced to a minimum
as the load would only be that due to the weight of the material
of which the railway or road surface is constructed, with in addition
the live load due to the traffic passing over it.

If the stream or water-course is diverted in a manner similar
to what has been indicated, the level of the discharge end of the
waterway will be considerably higher than the original course of
the stream, and it will thus be necessary to construct a series of
steps in the part of the channel on the low side of the railway to
break the flow of the water, as shown on the diagram, over which
steps the water would discharge. If the excavations should be in
rock, the discharge would be over a rocky surface and no building
would be necessary in forming the water channel.

When diverting a stream from its original course it is necessary
to guard against the forming of abrupt corners in the altered
channel, which would cause an obstruction to the flow of water,
and an endeavour should also be made to have the altered channel
constructed so that the flow at the point where it connects with
the original course will be as nearly as possible what it was previous
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32 EARTHWORK IN RAILWAY ENGINEERING

ing may result to the lands either higher up or lower down the
stream than the site of the culvert.

In order to prevent the lodgment of water on the upper side
of the embankment between the level of the diverted water channel
and the original level of the stream where it passes under the bank,
the ground should be made up to the level of the diverted water
channel if this can conveniently be done, as shown in Fig. 16, the

    

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embanking material used for the purpose being well consolidated
s0 as to prevent surface water damaging the embankment.

If the filling up of this area is too extensive an operation it will
be necessary to lay a pipe or construct a small culvert under the
railway embankment to drain this ground.

Every care must be taken in diverting the water-courses to see
that there is no drainage left along the original course under the
railway embankment, as serious damage may result through the
material becoming sodden and slips taking place.
CULVERTS AND DRAINAGE 33

Under certain circumstances it may be possible to take a road
and stream under the railway at one place by a bridge as shown in
Fig, 17.

Where the water-course is at a higher level than the formation
level of the railway and has to be carried across the railway, it will
either require to be taken under the railway in a syphon pipe or
over it by means of a pipe or box conduit. A syphon would be
adopted where there was not sufficient headway for railway traffic
to allow of the conduit being taken overhead (see Fig. 18). The
pipes forming the syphon would be of iron or steel and the joints
made watertight, and the piping would require to be capable of
withstanding the pressure of the head of water caused by the
difference in level of the top and bottom of the cutting, in addition
to any other pressure to which it may be subjected.

Lower Upper
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Fic. 18.—Syphon pipe under railway.

When the pipe or conduit is carried over the railway it would
be supported on a trestle bridge, or on a road bridge.

If supported on a trestle, as at Fig. 19, there is a danger of
drivers or firemen of trains meeting with accident when engaged
taking coal from the top of the engine tender, owing to their
not observing the pipe as clearly as they would the girder of a
bridge. By reason of this, and also on account of the extra cost
involved in constructing the piers and framework of a trestle it
may be preferable to divert the water-course so as to cross the
railway on an overbridge if there should be one near at hand.

In Fig. 20 the pipe is shown carried over the railway on a road
bridge, being supported on the outside of the main girders.

If the water-course is larger than can be conveyed in a pipe it
can be taken across the railway in an open conduit (see Fig. 21).

The author has knowledge of a case where a stream and farm
road were carried over the railway on one bridge (see Fig. 22).

Instead of conveying the water across the railway by any of the
methods described it might be taken down the slope of the cutting

E.R.E.—D
EARTHWORK IN RAILWAY ENGINEERING

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either in an open stepped conduit or in a pipe and led alongside the
formation of the railway into a watercourse at the end of the
cutting. This would, of course, necessitate the making of the
formation of the railway wide enough to take the conduit in addition
to what is required for the actual construction of the railway, and
the additional cost involved might be prohibitive.

 

 

 

Fic. 20.—Pipe carried over railway on road bridge.

Where a railway is constructed through a town, water, drainage,
and gas pipes will have to be dealt with, and provision made for
them when designing the bridges carrying streets over the railway
or other work.

The question of what drainage works are necessary for the pro-
tection of cuttings and embankments of railways is dealt with in
Chapter VI. 4

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in open conduit. railway on one bridge,
CHAPTER IV
EXECUTION OF EARTHWORK

For the execution of the work there will be a Specification, Schedule
of Quantities, and Contract Drawings.

SPECIFICATION

The requirements of the Contract Specification are referred to
in Chapter IX, and it will only be remarked here that so far as the
descriptive clauses are concerned they should be as full as possible,
both as regards the manner in which the work is to be executed and
the quality of the materials used in construction.

SCHEDULE

The general practice in preparing a Contract Schedule is to detail
as fully as possible the various items and quantities of work to be
executed in carrying out the work.

Under the heading of “ Earthwork ” the quantities of materials,
whether in road or railway cuttings and embankments, with their
situation in relation to the mileage marked on the general plan and
section hereinafter referred to, should be separately stated.

Where there is rock in any of the cuttings there should be a
separate item.

The quantities of materials in each item of work in bridges,
stream diversions, and culverts should also be scheduled in detail.

Sewers and drains which will be distributed generally all over the
work should be grouped together under one quantity for each
item.

Under the heading of “‘ Sundries” there should be included
general work such as office accommodation, the setting out of works,
scaffolding, watching, lighting, etc.

36
EXECUTION OF EARTHWORK 37

The Schedule when read with the Specification should leave no
doubt in the mind of the Contractor as to the character and extent
of the work to be executed.

In so detailing the Schedule the Engineer furnishes the Con-
tractor with all the information at his disposal, and the Detailed
Estimate when priced, on which the Contract Tender will be
based, will give, so far as can be seen when the work is let, what
the actual cost of the undertaking will be.

CONTRACT DRAWINGS

The drawings with which a Contractor is furnished to enable him
to execute the work usually consist of a general plan, a longi-
tudinal section, a sheet or sheets of cross sections, and detailed
cross sections giving width of road-bed or formation, depth of
ballast or road forming, the size of side ditches or water channels,
drains, etc.

He will also be furnished with typical drawings of culverts and
drains for the general drainage of the adjoining lands, and drawings
of special culverts or aqueducts for conveying water-courses over or
under the railway. The plans should be as complete as possible.

GENERAL PLAN (see Fig. 23)

The general plan is generally prepared to the scale of the Ordnance
Survey of 25344 ins. to a mile (gs), or a somewhat similar scale
if an Ordnance Survey does not exist, but where there are few divi-
sions of land a small scale plan can with advantage be used. The
plan should show the boundaries of adjoining properties, the centre
line of railway, the boundary fences on each side, the radii of
the curves, and the mileage measured along the centre line relative
to a fixed point.

The situation of the principal road and river diversions and
how they are to be taken over or under the railway, culverts,
and important water-courses crossing the railway, should also
be indicated on the plan, and a reference should be made at
each bridge or other work to the number of any detailed draw-
ings of the same. Dimensions should be marked on the plan
fixing the exact position of the straight portions of the railway
relative to existing buildings or fences. No mileage distances
EARTHWORK IN RAILWAY ENGINEERING

38

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EXECUTION OF EARTHWORK 39

should be given to the commencement or termination of the curves
as the radii will determine their exact position on the straight
portions of the line at each end. The positions of the boundary
fences which are ascertained from the cross sections should also be
indicated by dimensions from the centre line ; and so that the fences
will be erected in uniform lines it may be necessary to modify
somewhat the widths obtained from the cross sections.

LONGITUDINAL SECTION (see Fig. 24)

“The longitudinal section will show a profile of the natural
surface of the ground along the centre line and also the formation
level of the railway. It should be plotted to the longitudinal scale
of the 25-344 ins. to a mile Ordnance Survey, or to a somewhat
similar scale, and to a vertical scale of 1 in. equal to 20 ft. It will
be a convenience if the horizontal scale is the same as that of the
scale of the general plan. The various gradients will be marked
and also the height of formation relative to Ordnance datum at each
change of gradient.

For convenience of calculations in the field the gradients should
if possible, be stated at a regular figure per chain (66 ft.), per 100 ft.
or per 20 metres according to the particular measure of distance
in use.

As in the case of the general plan, the mileage of the line should
be marked on the section as well as the position of principal
bridges or culverts and a reference to more detailed drawings.
While the datum line of the section may for convenience be above
or below ordnance datum, all levels marked on the section should
be the height in relation to ordnance datum.

When fixing the level of formation endeavour should be made to
get the quantities of the materials in the cuttings and embankments
to balance so far as is consistent with the character of the materials,
keeping in view that certain quantities of the material may be
suitable for building, road-making, or other uses on the Contract,
and also that the excavated material will not occupy the same
volume in the embankment as in the cutting, and that an
allowance will require to be made for bulking. As regards the
allowance made for “bulking” of the excavations, it is usual to
assume when preparing the Contract Schedule that the material
40 EARTHWORK IN RAILWAY ENGINEERING

in a thoroughly solid embankment will occupy from 3 to 5 per
cent more volume than it formerly did in the cuttimg. The
“bulking” of rock taken by itself may be as much as 40 per cent,
but as the quantity of rock in railway embankment is generally
a small proportion of the whole, the figure of 3 to 5 per cent
above stated may be taken as a fair average for all classes of
material.

Regard should also be had to the desirability of having the material
from the cuttings run down the grade to embankment and with
as short a “lead” (haul) to embankment as possible, and it should
also be kept in view that the intervention of a rock cutting which
will take longer to excavate than a soft cutting, or of a tunnel or
viaduct will probably delay the excavations. For the more effective
drainage of the permanent way it is also desirable that the line
where through cuttings should have a slight fall to one or both
ends of the cutting. Ata change of gradient a vertical curve should
be introduced so as not to have a sudden change when passing from
one gradient to another. The maximum or ruling gradient will
be influenced by traffic requirements, but it is necessary that the
line where through stations, or where sidings join and where it may
be necessary to have carriages or wagons standing on the Main
Line, shall not be on a steeper gradient than 1 in 260. Where the
horizontal measurements are in chains (66 ft.) it is usual to make
this gradient 1 ft. in 264 ft. (4 chains).

CROSS SECTIONS (see Fig. 25)

The cross sections should be plotted to a natural scale of 1 in.
equal to 20 ft., so as to correspond with the vertical measurements
of the longitudinal section. For the purpose of ascertaining the
quantities of material in the cuttings or embankments required
for the contract schedule of quantities, and also for determining
the position of the boundary fences, cross sections should be taken
at every 66 ft., 100 ft. or 20 metres, according to the particular
measure of distance in use. Cross sections should also be taken
at intermediate points where the ground is irregular in order that
the quantity of earthwork may be more correctly ascertained.
For the Contract sheet of sections it is sufficient to give sections at
every 3 or 5 chains apart, the object being to give the Contractor
a general idea of the character of the work. The cross sections
EXECUTION OF EARTHWORK 41

will show the surface of the ground, the slopes of the cuttings or
embankments which have been determined upon after considera-
tion of the character of the strata obtained from the bores or
trial pits previously put down, and the boundary fences will be
placed from 7 to 10 ft. back from the top or bottom of the slope
according to whether the line is in cutting or embankment.
Another method is frequently adopted in this country—and
usually in America—which would avoid the necessity of taking
cross sections at every peg (except at points where the ground is

 

Fia, 25.—Contract—cross sections.

(a) In cutting. (b) In embankment.

very irregular) and still give the same information, viz. side widths,
edges of slopes, areas of cross sections, and cubic quantities of
earthwork.

Having completed taking the levels along the centre line and
obtained the reduced level of each peg and of the formation level,
the heights of embankments and depths of cuttings are known.
The Engineer then proceeds to set out and drive the slope stakes
opposite each peg, directly on the ground by means of a level,
staff, and tape line.

To illustrate the method (see Fig. 26) an embankment 10 ft.
deep will be assumed, 30 ft. wide at formation, and having slopes
of 1} to 1. The level is set up conveniently on the higher side of
the centre line, the staff is held on the centre peg A and reads, say,
12-50. The staffman then proceeds to some point B, which should
42 EARTHWORK IN RAILWAY ENGINEERING

be fully 30 ft. [15+(10 x 13)] from A since ground slopes downward.
The horizontal distance A to B is measured and found to be 36 ft.,
and the staff reading at B is, say, 14-50. Assuming for the moment
that B is at the bottom of the slope, the corresponding distance
A to B can be calculated. Since A C=10 ft., therefore C D=2:5 ft.
and B H=(14-5—2-5)=12 ft., ie. the height from formation to
assumed bottom of slope. The distance from A to B should therefore
be (12 ft. x 14)+ 15 ft. =33 ft., but as it was actually measured 36 ft.,
this at once indicates that the staffman must move back nearly
3 ft. towards A. This is done and a second reading of staff at F
is taken and same computation made. An expert stafiman can
frequently obtain the point with sufficient accuracy at the second
shot. The bottom of the other slope is similarly obtained, and the

 

Fic. 26.—Fixing slope stakes.

whole operation for one centre peg can be completed in com-
paratively few minutes. The same plant for the instrument will
usually be sufficient for several pegs on either side of it.

The areas can be readily obtained (see Fig. 27). The hatched
area OS T is a constant for each cross section, AC is given, the
horizontal distances A F’ and A M’ are measured and OC can be

computed. The area FSOTM is therefore equal to ae x40
AM’xAO AO AO
=—g (AP +AM)=>- xF'M’, and by deducting from

this the hatched portion the area of the cutting is obtained. Since
these areas are computed from actual field measurements it
eliminates any error in plotting or scaling cross sections.

A special form of field book ruled in columns is generally used
for entering up both field work and computed areas and cubical
contents of each cutting or embankment.

There are columns for chainage, peg level, and formation level,
also a column giving the height of formation, above or below
EXECUTION OF EARTHWORK 43

centre peg and slope pegs, and the distances of the latter from the
centre peg are also noted.

When a new line of railway is being constructed it may be advan-
tageous to acquire sufficient land to allow for future widening, say,
from a single to a double line, or if the line is at first constructed
for a double line of railway it may be considered desirable to
acquire sufficient land to allow of two additional lines of railway
being subsequently provided for future developments. By doing
so the land will no doubt be more economically acquired and save
the inconvenience of having to obtain further Parliamentary
powers or making additional agreements with landowners. Inci-
dentally, it may be remarked that the extra width of land so
obtained may be conveniently utilized for a service railway or over-

   

F Fria. 27,—Area of cross section.

land route for use during construction of the railway, which other-
wise would probably have had to be constructed on land temporarily
acquired outside of the boundary fences of the railway.

The contract drawings for culverts and drains will be more or
less of a general character, as the particular circumstances in each
case can best be determined when the works are in progress.

In works involving the construction of earthwork and masonry
it is desirable that operations should commence in the early spring-
time. It is thus important that the contract specification,
schedule, and drawings should be completed some months pre-
viously so that the Contractor may have ample time to prepare
his tender and also that the Engineer and his clients may be
able to give due consideration to the Contract Tenders, and,
further, that the Contractor may have full opportunity to mature
his schemes for carrying out the work and bringing forward plant
and materials. By this means the work would be begun under
the most favourable auspices and full advantage would be obtained
of the best season of the year.
44 EARTHWORK IN RAILWAY ENGINEERING

SETTING OUT OF LAND AND WORKS

The first operation in the actual construction is the setting out
of the land and works. Under the Contract Specification the
Contractor is held responsible for the accuracy in position of the
works, but in view of the possible legal questions which may subse-
quently arise as to the boundaries of the promoter’s property, it
is better that the centre line and the boundary fences be marked
off jointly between the promoter’s Resident Engineer and the
Contractor's Engineer without in any way prejudicing the pro-
moter’s position in the matter or relieving the Contractor of his
responsibilities.

The centre line of railway should be marked off by having pegs
about 14in, square by 15ins. long driven into the ground at distances
of 66 ft. apart, or other convenient length. Where the line is across
a tock surface chisel markings should be made or iron spikes driven.

The distances along the centre line would be made continuous
throughout the whole length and the mileage would be indicated
on flat pieces of wood or stakes 3 ins. wide by ? of an inch thick,
placed immediately behind each peg. The straight portions of the
line would be laid down accurately to the dimensions marked on
the contract plan and the curves put in to the radii marked on the
plan. The pegs on the straight portion would be ranged out by
means of a theodolite between the fixed points laid down from the
general plan, and the pegs on the curves by deflection angles from
the tangent points, transition curves being introduced where
required. The intersection points of the curves will in all prob-
ability be outwith the boundary fences, and it is therefore most
important that the tangent point at each end of the curves should
be very carefully marked. This is usually done by having a larger
peg for the tangent points and placing a smaller one on either side
transversely to the centre line. The tangent points should be
transferred to other pegs or fixed points in the line of one of the
boundary fences, the distance to the same being entered in a setting-
out book specially used for the purpose.

All measurements taken in connection with the fixing of the
centre line or transference of the marks should be made with a
steel band tape, and for setting out purposes a 5-in. theodolite is
very suitable both for accuracy and for convenience in use. For
EXECUTION OF EARTHWORK

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45
46 EARTHWORK IN RAILWAY ENGINEERING

approximate determination of intermediate points on a curve the
method of chords and offset measurements may be used, but the
exact position of any point either on a curve or straight should
only be determined by means of the theodolite.

The levels of the centre line pegs should thereafter be taken, and
a working longitudinal section prepared (see Fig. 28) on which will
be marked the level of each peg, the calculated formation level of
the railway, and the depth of cutting or height of embankment
below or above the level peg. It is usual to indicate the peg and
formation levels in black figures, the depths of cuttings in red, and
the heights of embankments in blue figures on the working
section.

When the railway covers a large tract of country a small scale
map, preferably 6 ins. to a mile ordnance, with the cutting and
banking materials indicated along the centre line in red and blue
colours respectively, is very useful for general purposes in locating
the site of the works.

When the centre line has been finally laid down on the ground,
the boundary fences should be pegged out from measurements
previously marked on the general plan. The enclosing of the
promoter’s property by the erection of walls and fences should
be entirely completed before any of the other constructive works
are proceeded with, and with a view to protecting the centre line
pegs it is desirable that the boundary fences should be erected as
soon as possible after the position of them has been marked off.

Previous to constructional operations being proceeded with at
any section, each of the centre line pegs for the length to be inter-
fered with should be carefully transferred to fixed points on the
boundary fence, so that their original position on the centre line
can be obtained at any time as the work progresses. The levels
of the pegs should also be transferred. These transfer pegs should
for convenience be placed all to the one side of the centre line,
and the particulars of situation and level should be noted in the
setting-out book.

Considerable inconvenience and expense to the Contractor is
incurred when it is necessary to remove only a few inches of material
from the slope of a cutting after it has once been dressed off to
a regular batter, and it is thus most important that the information
furnished by the Contractor’s Engineer should be strictly accurate.
EXECUTION OF EARTHWORK 47

CONSIDERATION OF GENERAL SCHEME OF OPERATIONS

Before proceeding with the actual operations on a contract of
any considerable magnitude the Contractor should carefully con-
sider the manner and order in which he proposes to execute the
whole work and the various portions of it. He will have looked into
this matter in a general way when pricing his Schedule, and when
the time limit within which he promised to execute the work
was under consideration ; but in view of the short time generally
allowed to prepare his Tender the modus operandi will require to
be revised, and the whole question again gone into.

In contracts of other than the smallest dimension, it is unusual
to enumerate in detail the minor works to be executed, such as
provision of drainage of adjoining lands, the carrying of small water-
courses over or under the railway, the diversion of gas and water
pipes or electric cables, the construction of roads and bridges
necessary for the accommodation of the lands intercepted, ete.
While the greater number of these works are necessary for the
proper execution of the undertaking, certain of them will require
to be determined by agreement with the proprietors of the land
passed through, or with public bodies, involving legal formalities.
The time so taken up, together with that occupied in the
preparation of special drawings, would very seriously delay the
commencement of a contract if it were necessary that these should
be finally decided upon beforehand. The Contractor must, there-
fore, keep in view the probability of such works being necessary
and his operations should be regulated accordingly.

In terms of his Contract Specification the Contractor may require
to take the whole risk of the materials in the excavations or under
the sites of the embankments proving different from what he
anticipated. While the journal of bores which the Engineer has had
prepared previous to the Contract Schedule being made up, and
to which the Contractor has access, may correctly represent the
character of the materials in the strata at the points where the bores
were put down, in view of the importance of the matter, the Con-
tractor may think it desirable to obtain further information by
putting down additional bores, or sinking trial pits. If he decides
to do so he would put the work in hand immediately after getting
48 EARTHWORK IN RAILWAY ENGINEERING

the contract, so that it could be going on simultaneously with the
other preparations he is making for having the work commenced.

The result of this check may not materially affect either the
total value of the work or the time within which the work can be
executed. It may, however, alter the order in which it was originally
proposed to execute the work and also the disposition of the neces-
sary plant, and it may be found that the expense of putting down
these additional bores was fully justified.

With the information previously obtained when making his
Tender, supplemented by the additional particulars he himself
obtains, the Contractor will lay out his works in a manner best
suited to fulfil the considerations which influenced him in pricing
his schedule in respect of the depositing of excavations in the
nearest embankment and other points already referred to.

He will first direct his attention to those cuttings which take
the longest time to excavate, or from which he expects to obtain
building material for use on the work. So that the work may be
carried on both expeditiously and economically it may be necessary
to proceed with cuttings at more than one point simultaneously.

SERVICE RAILWAYS

Tn addition to the ordinary lines of service railway required for
the removal of the excavations from the cuttings to the embank-
ments it may be, as already stated, necessary to lay overland
routes to take the excavations from the euttings to the embank-
ments past rock cuttings or the site of viaducts or tunnels under
construction. If there is not sufficient space within the boundary
fences for the overland route, additional land will have to be
temporarily acquired either by the powers of the special Act of
Parliament under which the works are being constructed, or by
agreement with the land proprietors. Apart from the possible
necessity for a service railway or overland route for the removal
of excavations, a line of communication is essential for the con-
veyance of constructional materials required for bridges, culverts,
etc., along the line, and for general convenience.

This temporary railway should be laid with a light section
of rail, generally flat bottomed, and weighing from 40 to 50 lb.
per yard, and would be fixed to light sleepers. The rails should
EXECUTION OF EARTHWORK 49

be placed to the gauge of the railway with which the new line will
connect so that building and other materials can be brought for-
ward from the existing lines of railway to where they are required
without the necessity of transhipping them. Generally the sleepers
of the service railway will be laid on the surface of the ground,
with only the inequalities in the surface removed. Where crossing
soft or marshy land some additional support may be necessary.
The gradient should not, as a rule, exceed 1 in 30, and even with
this steep gradient it will probably be necessary at certain places
to construct shallow cuttings or embankments. Where any cutting
or embankment requires to be done it should, if possible, be on the
line of the permanent railway, thereby saving expense.

When ravines or steep ground intervene it will either be necessary
to support the line on a temporary trestle with convenient ap-
proaches at either end, form a detour to obtain an easier crossing,
or entirely break the line of communication.

The service railway will, as a rule, be constructed for a single
line, but loop lines or passing places will be required at intervals,
of sufficient lengths to allow of trains used in conveying the excava-
tions from the cuttings to the embankments or to spoil passing one
another. These passing places should be situated at such points
as will cause the least delay to the earthwork operations, and in
fixing their position consideration should be given to the con-
venience for watering locomotives.

DRAINAGE WORKS

All works connected with the drainage of the land adjoining both
the cuttings and embankments, and under the sites of the embank-
ments, should wherever possible be executed before proceeding with
the other works, so as to reduce the damage to the earthwork from
insufficient drainage. Certain of the drainage outfalls may ulti-
mately be carried alongside the formation of the finished cutting,
or taken in conduits over the top of cuttings, and it will thus be
necessary to carry them in temporary channels until such time as
the permanent work can be executed.

The drainage works required are referred to under the heading
of “Culverts and Drainage” in Chapter II, and also m
Chapter VI.

E.R.E.—E
50 EARTHWORK IN RAILWAY ENGINEERING

CULVERTS, BRIDGE WALLS, AND RETAINING WALLS

Where culverts are required under embankments, these should
be constructed well in advance of the tipping of the materials,
so that sufficient time may elapse to allow of the masonry becom-
ing thoroughly hardened, and also that no delay may result
in forming the earthwork embankments. The same remarks
apply to the construction of abutment walls of bridges under the
railway and retaining walls required along the foot of embankments.
Where line cuttings are supported by retaining walls, the walls
should be built in trench from the level of the top of the wall. The
excavations above the level of the top of these walls should be first
removed, and, after the walls have been built, the excavations in
front should be taken out.

SLOPES OF CUTTINGS AND EMBANKMENTS

The slopes to which the cuttings and embankments should be
formed will depend on the character of the material. As a general
rule, cuttings in ordinary soft earth will stand at a slope of 1}
horizontal to 1 vertical.

The slope usually adopted for a solid rock cutting is } horizontal
to 1 vertical, and where soft material
overlies rock there should be a bench
3 ft. in width between the bottom
of the slope of the soft material and
the top of the rock (see Fig. 29).

These slopes of soft and rock may
have to be modified as a result of
the particulars obtained from bores,
the amount of water likely to be
met with, or other information in
regard to the strata.

In the case of embankments of
ordinary soft earth the slope of the upper 25 ft. should be 1}
to 1, between 25 ft. and 40 ft. 13 to 1, and below 40 ft. 2 to 1.
This matter is considered in Chapter VI, page 100.

The exact position of the top of the slopes of cuttings and the
bottom of the slopes of embankments should be accurately marked

 

Fig. 29.—S8oft cutting overlying
rock.
EXECUTION OF EARTHWORK 51

out from the cross sections, and where there are any inequalities
in the surface, additional ground levels should be taken and the
exact width from the centre line calculated. When the cuttings
and embankments are being formed the slopes should be brought
to proper line by means of wooden “ batter” rules or “ profiles,”
which may be about 6 or 8 ft. long. In depositing the earthwork
in embankments, timber cross-heads should be erected at every
2 or 3 chains, and in fixing the height of them an allowance should
be made for the subsidence of the embanked material. This
allowance for ordinary material should be about 1 in. to every
foot in height, and in making up the embankments the width should
be proportionately wider.

SOIL STRIPPING OF SURFACE

After having marked off the lines of the top of the slope of the
cuttings to be excavated, and the lines of the bottom of the embank-
ments—known as “lock splitting” of the surface—and after the
centre line and level pegs have been properly transferred, the soil
and turf over the area to be operated upon should be laid aside for
the subsequent soiling and turfing of the permanent slopes.

It is a common practice to deposit this material immediately
outside of the top of cuttings and the bottom of embankments, and
between them and the surface catch water ditches where, in the case
of embankments, it will act as a barrier, forming a temporary toe,
against which the embanking material will abut when being de-
posited.

PROCEDURE IN LINE CUTTINGS

The simplest form of a railway cutting is where the material to
be excavated consists of dry sand or gravel and where the depth
does not exceed 10 ft. In such a case the material would be taken
out to the full section in one operation. If the cutting exceeds
10 ft. and is less than 18 or 20 ft., a gullet would first be driven at
formation level (see Fig. 30). While the gullet is beg excavated
in advance, the wings BB on each side, above the level of
the top of the wagons, would be removed to the full section
behind where the excavations are proceeding in the gullet, and
loaded up simultaneously with the material from the face of the
52 EARTHWORK IN RAILWAY ENGINEERING

gullet. After the top level has been removed the wings CC of the
lower portion would be taken off. In trimming off the slopes
batter rules would be used and the surfaces trimmed from the top
down. It is usual to cut tracks square to the railway and trimmed
to the proper batter, these being at intervals of about 66 ft., and
the surface of the slopes is dressed uniformly between these
tracks. Where the cuttings are of a less depth than 15 ft. the
excavations would be removed by hand labour. If the cutting is
over 20 ft. deep and has of necessity to be removed by hand the
work would be executed in more than one level.

As regards the means adopted for disposal of the excavations,
if the “lead” to embankment or to spoil is less than about 80
yards ordinary barrows or light hand-carts would be used; from

   

i Gulleé —s
ieee

ie

Fig. 30.—Excavating cutting 10 to 20 ft. deep.

 

 

 

 

 

60 to 100 yards “ dobbin” carts drawn by a horse; and when
over that distance and less than about half a mile, wagons of a
capacity of 14 cubic yards, running on light rails placed at 3-ft.
gauge and drawn by a horse, would be used. When this distance
is exceeded 44-yard wagons, and worked by a locomotive with from
8-in. to 12-in. diameter cylinder, would be adopted. In the latter
case, the gauge of the rails would be the standard railway gauge
in use.

The number of wagons taken in a “rake”? would depend
on the gradient of the service railway, and whether the place of
deposit is at a higher or lower level than the cutting, but generally,
with 14-yard wagons and horse power a rake would consist of three
wagons, and with 44-yard wagons and locomotive power it would
consist of from seven to ten wagons. The load should, wherever
possible, be taken downhill.

In countries where sharp curves and steep gradients are the rule,
embankments are generally shallow, and any cuttings that exist
are of no great depth. In such cases it may be cheaper to obtain
EXECUTION OF EARTHWORK 53

embanking material from borrow pits situated alongside the line
of railway, especially where land is of little or no value.

When the cuttings exceed 15 or 18 ft. deep and consist of “ soft”
material or loose rock, a steam digger may with advantage be used.
If the quantity of material in the cutting is more than from 30,000
to 50,000 cubie yards it will generally be more economical to use
a digger. With a clean dry sand or soily material there may not

PO Gitta an
a) :

Say

Fic. 31.—Width required by steam digyer,

be much saving in cost, but with hard clay, boulder clay, hard-
bound gravel, shale or loose rock, which are but slowly removed
by pick and shovel, a considerable saving may be effected, and,
with all classes of material, the quantity excavated in a given time
may be two or three times greater when a steam digger is used than
when the material is removed by hand.

It is a common practice when the material to be excavated is
very hard to loosen it by blasting in advance of the cutting face.

 

Fia. 32.—Leaving wings on gullet.

The charges would be placed about 20 ft. in advance of the face of
the cutting and about the same distance apart and would be sunk
to about 12 or 15 ft. below the surface. Care should be taken to
see that the charges are at least 3 ft. from the formation slope of
the finished cutting, so that the slope may not be damaged. In
boulder clay, loose rock, or similar material, the explosive used
would be black powder, instead of dynamite or nitro-glycerine,
as would be the case if the material to be removed were solid rock,
the object being merely to lift the rock off its natural bed or
break up the boulder clay so that it may be the more easily
removed by the steam digger.
54 EARTHWORK IN RAILWAY ENGINEERING

The cutting of a single line of railway with a width of 17 or
19 ft. at formation level is too narrow to allow of a steam digger
being used, and it will be necessary to keep the level at which the
steam digger is operated about 3 or 4 ft. above formation, as shown
in Fig. 31.

When the width is unrestricted, as in the excavations for a depot
or series of sidings, a larger and heavier machine than would work
in an ordinary railway cutting may with advantage be used. It
is thus that in large canal undertakings considerable quantities of
excavations can be removed in a much shorter time and conse-
quently at a less cost than can be done in ordinary railway work.

In the removal of the excavations of a railway cutting long
gullets should not be driven in advance of the main excavations

 

 

Fie. 33.—Cutting into slope.

(see Fig. 32), as otherwise the weight of the projecting pieces may
draw or strain the material outwith the intended slope of the
cutting. The sides of the cutting should be battered back as the
work proceeds, the slopes being always entirely completed within
at least 100 ft. of the working face.

A very objectionable practice is to cut away the toe of the slope
when the excavations are being removed by a steam digger (see
Fig. 33), and thereafter to throw down the upper portion of the
wings to replace the part cut away. As a consequence a slip may
result through water finding its way into the back of the material
that has been thrown down. If the toe of a slope is so cut away
it should be made good by stone filling as referred to in Chapter VI,
page 112.

DISPOSAL OF EXCAVATED MATERIAL

In order to obtain the best results from a cutting it is necessary
that the means of disposal be most complete, while at the same
time a great deal depends on the management of the operations to
ensure that the work is skilfully executed. The usual mode of pro-
EXECUTION OF EARTHWORK 55

cedure in excavating a soft cutting and tipping an embankment
where a steam digger is employed is as follows.

Service rails to the standard gauge in use would be laid from
the cutting face to the tip ends at the embankment. A light
locomotive engine would work at the tip end, while a horse or
light locomotive would be employed at the cutting face, and a
heavier locomotive than that used at the tip end would run between
the cutting and the embankment. If the “lead” to embankment
is over two miles, more than one locomotive would be necessary
for running the earthwork trains, and passing places would also
be required at convenient intervals, probably every two miles.

 

 

Section
Fia. 34.—Arrangement in cutting—three lines of railway.

The general arrangement at the cutting face where there is
sufficient width is shown in Fig. 34.

A short distance back from the face a passing place or loop line
is provided for leaving empty wagons and taking away full wagons.
At the cutting face the service railway branches into three lines,
the steam digger being placed at the end of the centre road. The
train of empty wagons, in which there would be eight or ten wagons,
would be placed in the centre road behind the digger. An empty
wagon would be run by a horse through the “jump” or sharp
turn-out and placed at the end of each of the two side roads, so
as to be in line with the front of the digger. When each wagon has
been filled it is propelled or drawn out into the portion of the side
56 EARTHWORK IN RAILWAY ENGINEERING

road behind the “jump” and replaced by another empty wagon.
When the whole rake has been filled the next train of empties will
be due to arrive and these will be left in the loop while the loco-
motive engine, which has brought them forward, pulls out the full
wagons, and having pushed the train of empties into the centre
road behind the digger, the engine takes the full train away to
embankment.

With the two side roads there is no delay with the digging opera-
tions, as, when a full wagon is being replaced by an empty wagon
on one road the digger is filling a wagon on the other road. To
be able to get three roads it is necessary that the formation width
be not less than 28 or 30 ft., so that in a single line cutting

Hill
if ybehind Digger
Si ir

 

 

 

 

 

Fig, 35.—Arrangement in cutting—two lines of railway.

operations require to be carried out at a level of about 4 ft. above
formation level to get that width.

If the work is conducted at formation level in a single line cutting,
which would be about 17 or 19 ft. wide, it is necessary to have the
digger placed in advance of the wagon to be filled (see Fig. 35).
Tn this case there would be only two roads. Empty wagons would
be placed in the loop, and after each is brought forward and filled
it is placed in the straight road from which the whole rake is lifted
and taken to embankment.

A steam digger can work well in a cutting from 18 to 22 ft. deep.
In deep cuttings the work would be carried on at different levels
of 20 to 25 ft. between each. When the depth of a cutting is slightly
more than the bucket can reach the material is pushed into the
cutting by crowbars or is brought down by the operating of the
bucket.

The arrangement at the embankment end is shown at Fig. 36.
Full wagons from the cutting are run into the line A. The wagons
which have just been emptied are standing on the line B, and after
EXECUTION OF EARTHWORK 57

the engine which has brought forward the full wagons has been
uncoupled, it runs the empties back to the cutting. The light
engine for tipping is standing in the line B. The first of the
full wagons is set in motion by a pinch-bar and run down the
line C.

The most favourable conditions for depositing material in
embankment are obtained when the lines of railway are falling
towards the tip end. In high embankments the gradient can be
steepened and the upper or narrow portion subsequently made up.

On the diagram the gradient down to the tip end is shown to be
easy so far as the point X, but beyond that point it is much steeper,
but not more than, say, 1 in 30.

When the full wagon is within 3 or 4 yards of the tip, the front,
which is hinged on the lower edge, is opened by having the fastening

   

 

 

From A sae Pi re ae
Cutting Empty | Full yak adel oly bibl,
SUDO TOUTE Ey J ul Ee
+ 0 »h =
B! Plan, vee oniigemnnninias

PO x a) ;
Seotion alent say lingg

Fie. 36.—Arrangement at embankment end.

at the side thrown up by a man striking it with a shovel. The
end of the service road is elevated by having a few sleepers raised
above the level of the end rail, and when the front wheels of
the wagon strike against this buffer the body of it is thrown up
and the muck tipped out.

Meantime the tipping engine has got in behind the empty wagon
and immediately thereafter the second full wagon is run through
the crossing into the line D and emptied alongside of the first.
The engine with the empty wagon from the line C is taken out and
run into the line D, and the second empty wagon, having been
attached, both empties are taken out and placed behind the full
wagon at point A. The whole “rake” having been emptied in
this way they are placed in the line B to allow of another rake
being run into the line A, following on which the empty wagons
are run back to the cutting.

When on account of the shallowness of the embankment or when
completing the top portion of a high embankment the material
58 EARTHWORK IN RAILWAY ENGINEERING

has to be deposited on a rising gradient, it will be necessary for the
shunting engine to propel the full wagons right up to the tip end.

The position and number of the passing places already referred
to will be fixed by the time which is occupied in filling the wagons
at the cutting or emptying them at the embankment.

RISKS OF DELAY

When the excavated material is dry no difficulty is experienced
in tipping it, but if water is present in the cutting which cannot
be kept separate from the excavations, progress is retarded. If
the excavated material is gravel the water will probably have

 
 

Fia. 37.—Method of expediting emptying wagons.

drained itself off before the embankment is reached; but if it
should consist of clay or muddy sand, the material will most
likely have been converted into a thick paste, closely adhering to
the sides and bottom of the wagon by the time that the muck train
has reached the tip end. This adhesion of the material to the
wagons may be reduced by spreading a layer of clean gravel or
engine ashes in the bottom of the wagons.

For the purpose of expediting the work at the tip end, when bad
material is met with the following method has been successfully
adopted (see Fig. 37). One end of a chain was fixed between the
sleepers on the inclined road and after having been carried under-
neath several sleepers the other end was attached to the wagon
which was being tipped before it had reached the incline. The
tip engine, having given the wagon an extra hard push, the wagon
was sent down the incline, and on being held up by the tightening
EXECUTION OF EARTHWORK 59

of the chain it was brought to a sudden stop at the tip end and
the muck thrown out.

When the material is bad there may be considerable loss of
time in removing it from the wagons, and also by reason of
derailments, or wagons going over the end of the embankment,
in which case the wagons cannot be emptied quick enough to keep
the steam navvy constantly employed; but, when conditions are
favourable for disposing of the material, the reverse is generally
the case, and the supply of excavated material may have to be
augmented by having a squad of men working by hand labour
fillmg wagons at some other part of the cutting. In removal of
excavations there is always a portion of the slope which cannot
be reached by the steam digger, and it is usual to fill so many
wagons of each rake in trimming off the slope in the portion of the
cutting behind where the digger is working.

In wet weather there is also a great risk of delay by reason of
engines and wagons being derailed on the service railway. If
the material should be of a clayey description, which with water
is converted into a slurry composition, a quantity of it will
drop on the way to embankment, and it is thus very important
that the line of communication should receive proper attention
so as to avoid derailments. The further the embankment or place
of deposit is from the cutting the greater is the necessity for
keeping the service railway in good condition.

PROCEDURE ADOPTED IN FORMING EMBANKMENTS

If the embankment is over 20 ft. in height it should be brought
up in layers, these being, in the case of high embankments, from
15 to 20 ft. thick. When the width at the tip end is less than 30 ft.
two wagon roads would be used in the manner already described ;
but when the width is greater than 30 ft. additional roads are
necessary, an extra road being laid for every additional 15 ft. in
width.

When there are three or more lines at the tip end, one of the
centre lines would be used for holding the empty wagons after
the material had been tipped in the side roads. The centre roads
would be carried forward simultaneously with, but a little in the
rear of those at the side. In forming an embankment the two
60 EARTHWORK IN RAILWAY ENGINEERING

outside roads should be at the extreme width of the completed
embankment, as, if it should be necessary to slue them for the
purpose of subsequently adding to the width, there is a tendency
for the additional material to slip on that which had previously
been deposited, the whole object being to get a thoroughly
consolidated homogeneous mass.

When forming embankments the centre should be kept slightly
above the level of the outer edges, so that water falling on the
surface will easily drain off, but care should be taken to ensure
that this is not carried to excess as otherwise the material subse-
quently deposited will have a tendency to slip.

In widening line embankments or in forming an embankment
on very side-lying ground it is usual to cut tracks or benches in
line of the railway on the sloping ground so as to form grips for the
embanked material. These should not be placed closer than 15 ft.,
and they should have a slight fall longitudinally so as to prevent
the lodgment of water.

A deep trench cut along the toe of the new slope and immedi-
ately inside of the soil which has been thrown up into a mound
to be subsequently used for soiling the slope, will also assist in
preventing any movement of the newly deposited material. Where
the side-lying ground is pasture land a system of digging or of
ploughing the surface to a depth of 9 in. is preferable to
forming benches. This matter is further considered in Chapter VI,
page 119.

The question of using side tip wagons instead of end tip wagons
has frequently been discussed; but the consensus of opinion is
that end tip wagons should in general be used for forming railway
embankments where they are of a less height than 30 ft., but
where the embankments exceed 30 ft. and are of considerable
length the use of side tip wagons would expedite operations and
might allow of the material from several steam diggers being
deposited simultaneously.

When depositing excavations in embankment by means of side
tip wagons the whole train of wagons, or as many of them as
can be conveniently accommodated, will be run along the service
railway to the site of the embankment and emptied simultaneously.
By doing so the work will be considerably accelerated, provided
wagons can come forward in sufficient numbers from the cuttings.
EXECUTION OF EARTHWORK 61

In a wide embankment formed by side tipping, the work of
depositing the material is commenced at the edges of the embank-
ment, and after the service rails are raised to a height of 15 to 20 ft.,
which would form the level of the first lift, the material will be
then deposited on the inner side of the embankment and the
service road will be gradually slued towards the centre.

ALLOWANCE FOR SUBSIDENCE IN FORMING EMBANKMENTS

The allowance for subsidence in forming an embankment
will depend on the character of the material and the weather
conditions existing when the work is being executed, and also to
which it will be subsequently subjected. This question is referred
to in Chapter VIII, page 140; but it is here remarked that by
working traffic over the bank as much as possible while it is being
constructed, it is made very compact. Contractors’ service railways
running on the bank very materially assist in consolidating it; but
while the temporary railways are in use it is necessary that the
surface be kept as free as possible from hollows so as to prevent
water collecting which may sink into the bank, and thereby
cause damage. The longer time that can be spared before the
permanent railway is laid the better it will be for the embank-
ment.

Before the permanent ballast is put down the surface should be
brought to proper line and level. If the top is low it should be
raised to the proper height with selected material—preferably
good hard clay—which will form a firm seat for the ballast, and
if the surface is high it would require to be reduced. It is well,
however, to keep the bank a little high to allow for ultimate
subsidence.

Considerable difficulty is experienced in countries where heavy
rain-storms occur through banks subsiding after the traffic has
been brought on to them. If the banks are made from borrow pits
they should be formed as early as possible so as to give them an
opportunity of settling during the rainy season. In the event of
the railway being brought into use before the first heavy settle-
ments have taken place, the railway should only be temporarily
ballasted with sand or material from a hard cutting, and subse-
quently re-surfaced and fully ballasted after settlement occurs.
62 EARTHWORK IN RAILWAY ENGINEERING

CUTTING IN ROCK

The method adopted for the removal of rock from the excava-
tions will largely depend on the character of the rock, and whether
it is proposed to use it for building or other purposes on the contract,
or merely to run it to spoil embankment.

In the event of the removal of the rock being the primary con-
sideration the material would be taken out regardless of its value,
the object being to remove the maximum quantity at the minimum
cost. Blasting, if allowed, would then be carried on continuously,
and if there is a greater uniform depth than from 12 to 14 ft. opera-
tions would be carried out at more than one level (see Fig. 38).

 

Fig. 338.—Excavating rock.

It will generally be found more convenient to take off one lift con-
tinuously for some distance before proceeding with the removal
of the rock immediately underneath, but the mode of procedure
will largely depend on the means for disposal of the excavated
material. The blast holes would be of a depth of about 6 ft. and
placed at about 16 ft. apart, but no hole should be closer than 3 ft.
to the finished batter of the cutting, so as to ensure immunity from
damage to the rock outwith the finished slope. Three men would
be engaged at each bore hole, if the drilling is done by hand, while
other ten or twelve men would be engaged loading up the excavated
material.

The material after being loaded into skips would be lifted
and emptied into wagons either by steam cranes placed on the top
EXECUTION OF EARTHWORK 63

of the cutting or by travelling cranes working on the line of railway
at formation. As a preventive against stones flying out of the
cutting the blast hole should be covered over and weighted down.
A good cover consists of pieces of trees 6 in. in diameter and 6 it.
long tied together by chains. If blasting is prohibited by reason of
the proximity of property, public highways or adjoining railways,
the materials would be taken out by pinch-bars. This matter is
further referred to in Chapter V, page 78.

If the removal of the rock from the cutting is not the key to the
completion of the work, it would be taken out in large masses in a
manner somewhat similar to that usually adopted in quarrying
operations. In the case of freestone, limestone, or other stratified
deposit the rock would be shifted by splitting it with wedges or
by what is known as the “ plug and feather” method, and by
raising it off its natural bed by means of crowbars. Small charges of
gunpowder would be used to shake large posts of rock without
shattering it.

Where granite is met with in large quantities blasting will be
regularly carried on, and the larger masses which are brought down
will be subsequently split up into smaller pieces in a similar manner
to the softer stratified rock.

For the removal of the rock so quarried the blocks of stone which
are to be used for building or other purposes will be run out into
a depot set apart for the purpose, while the smaller material or
debris would be put into tip wagons and run to spoil embankment,
or it may be used to advantage for pitching slopes exposed to
water, making up roads, or broken up for concrete, or crushed for
use as sand, or other purposes.

When rock is met with in station depéts, where there may be
platform fronts to be formed in the rock, a track would be cut either
by shearing the rock by hand labour or by means of a channelling
machine. This would be done previous to the removal of the centre
portion, and there would thus be no risk of damage to the sides
of the finished cutting.

EXAMPLES OF RAILWAY CUTTINGS

The following examples from actual practice illustrate the
manner usually adopted in the removal of excavations from rail-
way cuttings.
64 EARTHWORK IN RAILWAY ENGINEERING

Hach of the examples is for a single line of railway where the
operations are carried on in a confined width and consequently
require more consideration than where there is greater freedom for
work.

(1) Fig. 39 is a profile of a railway cutting for a single line of
railway, the greatest depth of which was 46 ft. and the quantity
of material to be excavated was 80,000 cubic yards. The material
consisted of sand and gravel for a depth of 6 ft. under the surface,
underlying which there was clay until within 10 ft. of formation,
while the bottom 10 ft. consisted of “ faikey” fireclay. The line
embankment which was situated at the upper end of the grade
required about 60,000 cubic yards of material, and the balance
of 20,000 cubic yards had to be deposited in a spoil bank at the

 
  
  
  
        

To line Embankment —>
Spoil Bank <C MR

alongside baa sz
Quantity of Material in Cutting--80,000 Cub. Yds
Gradient 1 in 40

0 Fur aM/
Fia. 39.—Example of railway cutting (1).

  

 

lower end of the cutting. The portion of the cutting shown hatched
at the lower end was excavated by hand labour, and run to spoil,
and a short length at the upper end, sufficient to allow of a steam
digger being erected, was also removed by hand.

The digger was wrought through the upper portion of the cutting
on a rising gradient taking off the left-hand half of the excavations,
following on which it was run back to the point of commencement
taking off the right-hand half. It was then run along the service
railway to the point A and let down a steep slope to the point B.
The triangular portion A, B, C was then taken out, it being necessary
to carry on operations at a level of about 5 ft. above formation, in
order to get a width of 30 ft. which was necessary for operating the
“Ruston” digger which was used. Thereafter the digger was again
tun through the cutting from the lower end, working this time at
formation level. The “ faikey” fireclay of the lower 5 ft. was
blasted out in front of the digger and lifted by the digger bucket
into wagons placed behind the point where the blasting operations
were proceeding, the digger in this operation being used merely as
EXECUTION OF EARTHWORK 65

acrane. The whole of the work in each of these operations was
carried out on rising gradients, thus allowing of any water that
was met with in the working face having a free outfall.

(2) The cutting of which Fig. 40 is a profile had a maximum
depth of 37 ft., of which the bottom 11 ft. consisted of solid rock,
while the quantity of material to be excavated was 130,000 cubic
yards. The material on the top of the solid rock consisted of
boulder clay in certain places, while at other places loose rock was
met with. Operations were commenced at the lower end of the
cutting by hand labour until a depth of face of 8 ft. was obtained,
when a digger was erected and taken through the cutting on the
top of the solid rock, the excavated material being run to embank-
ment at the lower end of the gradient. Blasting was resorted to in
front of the digger for the purpose of loosening the soft rock and
boulder clay. After the material on the top of the solid rock had
been removed the excavation of the solid rock was proceeded with
by hand labour, operations being carried on both at the lower end
and at the centre of the cutting, in both cases working up the
gradient of the railway. The material from the lower end was run
down grade to the embankment, while that from the upper end was
taken to embankment up the grade. The excavated rock was
lifted into wagons by means of steam cranes placed on the top of
the slopes of the cutting. Water was met with in the upper part
of the cutting, and this had to be drained off by shearing a track
through the rock to the working face at the lower end of the
cutting.

(3) In the case of Fig. 41, which was also for a single line of
railway, the cutting was 43 ft. deep, while the total quantity of
material to be excavated was 245,000 cubic yards. The cutting had a
length of 674 chains (1485 lin. yds.), and consisted of fine sand with
a large volume of subsoil water for a length of about 18 chains at
the upper end, hard boulder clay, which was perfectly dry, for a
length of about 19 chains (418 lin. yds.), hard clay with water coming
through open fissures caused by mineral workings, for about 163
chains (363 lin. yds.), and hard clay without water for the remain-
ing distance of 14 chains (308 lin. yds.).

The excavated material had to be run to embankment
from the top end of the cutting. The fine sand at the upper
end was excavated by hand labour on a rising gradient, which

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EARTHWORK IN RAILWAY ENGINEERING

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EXECUTION OF EARTHWORK 67

had just sufficient fall to allow of the water draining itself
off. In the removal of the sand, side and cross ditches were
cut so as to have the material when put into wagons as dry as
possible. A steam digger was set to work at the point B, and took
off one half of the cutting so far as the point C, from which point
the digger could reach the full section of the cutting as far as the
point X. The excavated material was run back through the sand
cutting to the embankment. In excavating the portion of the
cutting through the wet clay on a falling gradient it was necessary
to have a steam pump, which was erected on a carriage placed
immediately behind the digger, for the purpose of raising water from
a sump placed at the working face from which the water was
pumped into a drain laid at the top of the cutting. The remainder
of the cutting was removed by a heavy digger, working at a level
of 5 ft. above formation and the lower portion was subsequently
removed by means of a lighter digger working at formation. The
means adopted to support the slopes of this cutting through the
wet sand are referred to in Chapter VI, page 115.

CROSSING BOG OR MOSS LAND

The surface of a bog consists of peat, coarse grass, heather, etc.,
and is of a very porous description. If the skin of the bog is un-
broken it has a considerable bearing capacity, and if it can be
drained the bearing capacity is very largely increased.

If drainage of the surface can be effected no great difficulty will
be experienced in taking a railway across it; but if, on the other
hand, natural drainage of the surface is impossible the construction
of the railway may only be executed with difficulty and at great
expense, and the subsequent maintenance will also be a costly
item. The ideal railway across a bog is where the railway is either
laid on the surface or on a shallow bank and where the bog has a
natural drainage. The bog land will be of very little value and ample
width should be acquired to make the drainage as perfect as possible.

Fig. 42 shows a section of railway crossing bog land. Ditches
4 ft. wide by 4 ft. deep were cut on either side of the railway 40 ft.
distant from the centre line and cross ditches 3 ft. wide and 4 ft.
to 3 ft. deep were cut from the longitudinal ditches to within 18 ft.
from the centre line and 33 ft. apart. Part of the turf removed
68 EARTHWORK IN RAILWAY ENGINEERING

Tl
-

\
L

|
v

 

 

Fic, 42.—Cross section of railway through bo~ land.

 

is , .
Cross ditches 3 wide
at 29 centres

 

 

from the ditches was used for levelling up any
inequalities in the surface of the ground on
which the railway was to be constructed, the
object being to strengthen the natural surface
of the ground. Brushwood and branches of
trees were afterwards laid on the surface for a
width of 10 ft. on each side of the centre line
and to a depth of 2 ft. 6 in. depending on the
springy character of the ground, the lower
half being laid with the branches in line of the
railway, and the upper half laid crosswise to
the line of the railway. The brushwood was
covered over with mountain till or clay, which
generally underlies the peat and is found along
the edges of the bog. On the top of the clay
the permanent way of the railway was laid.

The ballasting of the permanent way con-
sisted of ashes or gravel as the slag or broken
granite or whinstone generally used cuts
through the clay covering the brushwood.
With a view to more uniformly distributing
the load on to the brushwood covering, the
sleepers of the permanent way were placed
closer together than usual, leaving only
sufficient space for the proper packing up of
the sleepers.

If further drainage is thought to be necessary
than above referred to, an additional longi-
tudinal ditch could be cut on each side of the
railway, in which case the cross ditches con-
necting the two longitudinal drains may be
placed further apart. In the event of any
banking material requiring to be deposited on
the top of the brushwood care should be taken
to ensure that the weight of the banking is
placed evenly on each side of the centre line
simultaneously, otherwise the unequal loading
will tend to break through the surface of
the bog.
EXECUTION OF EARTHWORK 69

It is desirable that the ditches for the drainage of moss land
should be cut nine or twelve months previous to the laying of the
permanent way, and it is also well that the laying of the brushwood
should not be commenced until after a spell of dry weather.

On account of the levels of the railway it may be necessary to
have part of the line when entering bog land in cutting, and if the
bog is very soft it may be necessary to deposit embanking material
down to the solid ground underneath. No clayey material should
be used for this purpose on account of the water of the bog
converting it into slurry. The best material for the purpose
consists of the excavations from a rock cutting. If the railway
should be in cutting through bog land and the peat is of a somewhat
firm description, it may be found sufficient to replace a depth of

 

 

Fic. 43.—Section of railway approaching bog.

2 or 3 ft. of the peat by clay closely compacted, on the top
of which brushwood and trees should be placed as in the manner
already described.

For the drainage of the railway in a bog cutting deep ditches
should be formed along the bottom of the slope on each side.

Fig. 43 shows a section of.railway approaching a bog. The
bog was contained on all sides and there was no natural drainage.
Before entering the bog land a sand cutting 55 ft. deep had to be
cut through, and in forming this cutting a drainage outlet for the
bog was obtained, otherwise the line across the bog would have
been much more difficult to construct.

Where the bog cannot be effectively drained the various works
of levelling the inequalities in the surface, the laying of brushwood,
and the subsequent claying over of the brushwood should receive
special attention. This may not prove effective, and it may
be necessary to fill up the bog along the line of railway with
70 EARTHWORK IN RAILWAY ENGINEERING

embanking material. The subsequent maintenance of a railway
across bog land may be very expensive by reason of breaks taking
place in the surface and the necessity for depositing material in
order to get a solid foundation.

WIDENING OF EXISTING RAILWAYS

In executing the widening of an existing railway the first con-
sideration must be the safety and the regular working of the traftic
on the railway generally. Trains will no doubt be so frequent that
possession of the railway can only be obtained during the night
or on Sundays, and any operations during the day will require
to be executed entirely clear of the running line.

 

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gil O38

Fia. 44.—Widening of railway—single to double line.

 

 

ld
Fra. 45.—Widening of railway—two lines to four lines.

The widening work should be fenced off from the existing rail-
way and any crane or steam digger should be so clamped or con-
trolled that in swinging round it shall have a clear distance of
6 it. from the nearest rail of the running line.

Tf the widening is of a single to a double line the total width of
the formation of the railway will be increased 11 ft. (see Fig. 44),
while if the widening is from double line to four lines the formation
width will be increased 17 ft. on each side (see Fig. 45).

It will thus be seen that in the case of the doubling of the single
line there will not be clearance for a digger to be employed, and the
excavations will, therefore, require to be removed by hand labour.

In the case of widening from two to four lines the operations
will not be so restricted and a steam digger can be used if desired.

If the material in the soft cuttings will stand at a steep slope for
EXECUTION OF EARTHWORK 71

a time, it will generally be found convenient to run a gullet through
the cuttings at formation level, so that the materials can be taken
from both ends of the cutting to the same embankment, and it
will also allow of the material in the slopes or stone from rock
cuttings being removed simultaneously with the excavations at
the ends of the cuttings.

The operations should be proceeded with at as many points as
possible along the route of the widening, attention being more
particularly paid to the cuttings from which there is the largest
quantity of material to be removed, and to the removal of stone
in rock cuttings.

It may be necessary to take part of the excavations to an embank-
ment separated from the cutting by a bridge or viaduct which
requires to be widened, or to a spoil bank situated away
from the widening work, and it will be an advantage to excavate
the material at intermediate points, as above referred to, filling the
material into wagons placed on the Main Line during the night or
on Sundays.

It may also be possible to arrange for trains of excavations to be
run over the existing railway from cuttings to embankments
situated at a distance or to a spoil bank between traffic during the
daytime. Storage sidings for full and empty wagons shall,
therefore, require to be provided at the widening work, and there
should be no shunting operations on the existing railway.

Any temporary connection with the existing lines should be under
the control of the nearest signal box, and when the excavations are
being removed from the cuttings into wagons placed on the running
lines a flagman should be stationed at each end of the operations
to warn the men of the approach of trains.

The traffic on the running lines should be conducted by the
Railway Company’s engines, and the men and the wagons for the
removal of the excavations should also be supplied by the Company.

It will generally be found that the most suitable wagons for the
removal of the excavations are those with sides about 3 ft. high and
with folding down doors extending the whole length of the wagon.

Care should be taken to see that the wagons are not so fully
loaded as to cause the material to spill over on the ballast of the
running line.

At the point on the existing line where the material is being
72 EARTHWORK IN RAILWAY ENGINEERING

loaded into wagons the ballast should be kept clean by covering
with old sleepers or sacks.

In rock cuttings where the material is of commercial value
quarrying operations can be proceeded with during the daytime,
and the stone can be loaded into wagons placed on the existing line
at night or on Sundays.

If the soft excavations are of too hard a description or if rock
is to be removed, blasting can be resorted to, but as there may be
only one or two occasions during the day when there is a long
enough interval between the passing of trains, a number of charges
should be fired at one time. The firing of the charges should only
be done after permission has been given by the look-out man who
has previously arranged the matter with the signalman in the
nearest signal box.

EARTHWORK CONSTRUCTED BY COOLIE OR BLACK LABOUR

In countries where coolie or black labour has to be dealt with,
the cost of labour is so low that it would be entirely out of the
question to employ costly plant to execute the work.

It is usual to sublet the work in sections or lengths of two or three
chains, and both men and women assist at the work. A large number
of hands are employed, and the construction of the cuttings and
embankments is carried out very speedily. The natives fill their
baskets with pick and hoe, and carry them on their heads, except
in the case of long loads, when donkeys with baskets or gunney
bag panniers may be used.

In some countries light wagons running on a railway of about
2-ft. gauge and pushed by hand are used for conveying the material
a distance. Cuttings and banks are formed independent of one
another, but instead of depositing the excavations from the
cuttings into the embankments they are taken to spoil alongside
the railway and the material for the banks is obtained by excava-
tions from borrow pits, except in the case of the part of the
cuttings which immediately adjoin the banks, where it is more
economical to put the material into the embankments rather
than take it to spoil. While this method of procedure entails the
handling of a much greater quantity of material than would be the
ease if the practice of making up the ewhankment from the line

<
EXECUTION OF EARTHWORK 73

cutting were followed, it is considered the best arrangement in
view of the system of letting out the work which is adopted.

For the making up of shallow banks and the lower portion of
high banks, the material from the borrow pits is simply piled on
the bank, and in high banks the borrow pits immediately adjoin
the end of the bank. The banks should be carried up in layers
of two or three feet for the full width and over the whole length,
and in depositing the material, the natives should be made to walk
over what had previously been deposited so as to have the banks
as compact as possible. By the constant walking to and fro a very
solid and satisfactory bank is obtained. In executing the work
in this manner there is no delay such as is experienced where
wagons are used, and where there may be interruptions by reason
of them not being timeously forwarded. In excavating rock hand
boring tools are generally used, these being considered more
economical than machine drills, owing to the supervision which is
required for the latter.

SPECIAL METHODS ADOPTED IN FORMING RAILWAY
EMBANKMENTS

In countries where there may be long stretches of level or prairie
land, or where the ground may be comparatively uniform in level,
and where there may not be sufficient depth or quantity of material
to be excavated to warrant the use of heavy plant, scraper machines
are largely used.

The earth is loosened by having the surface ploughed over, and
after the surface has been broken up, the material is taken to
embankment by a drag scraper, where the lead may be from 100
to 200 ft. For longer leads a wheel scraper is used, as it is more
economical.

In crossing long stretches of level ground the railway will in all
probability be on a low embankment so as to obtain through
drainage and immunity from snow-drifts, and if the embanking
material is to be obtained from the ground alongside the railway,
it can conveniently be deposited by means of a grader working
along the foot of the slope and casting up the material as it goes
along. The embanking material so deposited will be very loose,
and it will be well to have the upper 2 or 3 ft. made up by depositing
74 EARTHWORK IN RAILWAY ENGINEERING

the material with drag or wheel scraper for the purpose of consolidat-
ing it.

These machines are referred to under Chapter V, dealing with
Contractor’s plant.

In the construction of railways in countries where there is plenty
of timber and where the obtaining of sufficient embanking material
may involve considerable delay in bringing the railway into opera-
tion, timber trestle structures have been erected to cross deep
ravines. These have been placed not with a view to being perma-
nent, but to suit the purpose for the time being, it being intended
to subsequently replace them by earthen embankments. The
execution of this work can be proceeded with at a time when it is
most convenient, and does not necessarily incur any serious inter-
ruption of the regular traffic working of the railway.

In delaying the filling of the embankments an opportunity is
given to the Engineer to ascertain what size of culverts should be
provided at crossing of streams.

HYDRAULIC METHOD

A large amount of this work of filling in trestles has been done
in America, and the method of carrying out the work of placing
the material in embankment by hydraulic means would, under
certain conditions, appear to have its advantages.

Not infrequently slips of considerable extent have taken place
shortly after the opening of a line for traffic, and the material
which it is necessary to remove can be conveniently disposed of by
filling in trestles at a cost not exceeding that of running it to spoil.
If, however, the material requires to be specially excavated and
land can be obtained free or at little cost, the hydraulic system
commends itself. It has also the advantage that there is no delay
by reason of muck wagons blocking the traffic on the railway.
For the success of this method it is a necessity that there should
be an abundant supply of water with sufficient pressure to operate
the plant. Under ordinary circumstances it would not be economi-
cal to erect power stations for the purpose of obtaining the necessary
pressure.

The operations consist essentially of the washing out of the
material from the side cutting or borrow pits by means of a jet of
water under high pressure, and the conveying of it to the ground
EXECUTION OF EARTHWORK 75

to be embanked by means of wooden troughs or flumes which are
raised or slued as may be necessary as the work proceeds. In the
building up of the embankment various means are adopted to dam
back the slurry.

On the Northern Pacific Railway a method successfully adopted
was to deposit alternate layers of earth and straw. The earth was
spaded out from the inside, and on the top of it was laid a bed
of straw, this being compacted by another layer of earth. The
embankment was carried up in this manner until within a few feet
of the surface of the railway, and the upper layer was afterwards
formed with material deposited from wagons in the usual way.
The deposited material became remarkably solid in a very short
time and the embankment was entirely free from subsidence.

EXAMPLE OF EXCEPTIONALLY HEAVY EARTHWORK

The execution of exceptionally heavy earthwork on a line of
railway in New Jersey is worthy of attention.1

The line has been formed across country with the object of
reducing the distance and also improving the curves and gradients
which previously existed on a former line of railway.

By the former route the length between the points of termination
was 40 miles, while by the new line the distance was reduced to
284 miles. On the former line the maximum curve was 6° 54’
(831 ft. radius), and the maximum gradient was 1-14 per cent (1
in 87-7), as against 3° 30’ (1637 ft. radius), and 0-55 per cent (1 in
181-8) respectively by the new line.

The excavations and embankments are of exceptional magnitude,
there being 7,315,000 cubic yards of excavations and 14,621,000
cubic yards of embankment. There is thus an excess of 7,306,000
cubic yards of embankment which had to be obtained from side
cutting or by the bulking of the rock when put into embank-
ment.

One of the embankments extended in length to three miles and
had a height of from 75 ft. to 110 ft., the quantity of material
required to fill it being 6,625,000 cubic yards.

The high banks were brought up in lifts of 30 ft., timber trestle
bridges being largely used for the purpose of tipping the material.

1 Engineering Record, 17th April, 1909.
76 EARTHWORK IN RAILWAY ENGINEERING

In forming some of the large embankments cable-ways were
adopted. In one instance a cable-way had two spans of 1000 ft.
and 1200 ft., with three wooden towers 60 ft., 150 ft., and 135 ft.
high respectively. The working of the cable-way is described as
follows :—

“Tt is essentially a suspension bridge, carrying a cage or platform
on which a 3-ft. track is laid. The cage is so made that it can be
moved forward along the main cable as fast as the embankment
is built. The cars are pushed to the very edge of the fill and dumped
and then pushed out on the cage, which is of sufficient length to
hold eight cars, or a gross load of 48,000 Ib. As the fill progresses
the suspended track is shifted along the cables by placing clamps
12 ft. apart in advance of the previous ones and hanging from them
a suspender rope with an adjustable tackle, to which a needle beam
is fastened to carry the new stringers and the additional track.
On account of the sag in the cables the lengths of these suspenders
and other tackle are made adjustable.”

It is claimed by this method that there is greater ease of working
when the excavation consists of rock or large boulders which might
seriously damage a timber structure.

The borrow pits from which the extra embanking was obtained
were situated above the level of the banks, and in some instances
the loaded tip wagons were allowed to gravitate to the bank, being
kept in check by having one end of a cable, which passed round
a drum, attached to them, the other end being connected to the
railway wagons which were drawn back to the pit for refilling.
CHAPTER V
PLANT USED IN EXECUTING EARTHWORK

AN axiom in manufacture by machine tools, which is equally
applicable in the execution of earthwork, whether by hand or
machine labour, is that the system or machine which accomplishes
a given result quickest, best, and at the same time at the least cost,
is the one to be selected.

REMOVAL OF EXCAVATIONS BY HAND LABOUR

Soft excavations —The shovel is the tool in general use for the
removal of soft excavations by hand labour. The iron blade of the
shovel is of a hollow or scoop shape, and is usually sharp pointed.
Where the material to be removed is of a wet or muddy description,
the shovel would be broad pointed, and the sides turned up so as
to better contain the material.

Except in the case of loose earth, or when the material is easily
removed, a pick would be used in conjunction with the shovel to
loosen it.

Where the material is of a tenacious, clayey description and free
from stones, it may be dug out by a sharp-pointed shovel with a
thick upper rim, similar to what is on an ordinary broad-pointed
spade, and would be used in a similar manner.

It is very desirable that the shovel, spade, or pick should be of
as light a character as possible, consistent with the rough usage to
which it is subjected, in order that the energy expended in handling
the tool may be reduced to a minimum.

Rock excavations.—In excavating shaly or loose rock, or rock
which can be removed from its natural bed without blasting, a pick
is used. The point of the pick is driven into the joints or clefts
of the rock, and, by using the curved back of the pick as a fulcrum
and pulling back the end of the shaft, a considerable pressure can
be brought to bear on the point in removing the tock.

77
78 EARTHWORK IN RAILWAY ENGINEERING

A pick for removing rock has generally a broad or chisel-shaped
point at one end and rounded point at the other end. By having
a broad point there is more of a knife edge, while at the same
time equal strength, and this allows of the point of the pick being
inserted into a closer joint than a blunt rounded point would enter.
The pick in use for the removal of soft material is rounded at both
ends.

A crowbar chisel-pointed at one end and round-pointed at the
other end, similarly to the pick, is used where greater pressure is
required than can be obtained with a pick. For the purpose of
getting a leverage a piece of wood, stone, or other hard material
at hand is placed under the bar so as to act as a fulerum when
prising up the rock, and by inserting wedges in the open joint the
bar can be released or tilted up to allow of the fulcrum being
shifted closer to the joint, thereby getting into a better position to
further raise the rock from its bed. Where a large block of rock is
being lifted from its bed two or more crowbars may be used simul-
taneously.

Where the rock is of a close or solid description a groove is formed
in it with a pick, along the line on which it is to be split, and iron
wedges are driven at intervals by blows
from a sledge hammer. The wedges are
placed at about a foot apart and the blows
applied on every alternate wedge when
passing over them in one direction, driving
the intermediate wedges when coming back
over them. The rock is, of course, more
easily split along its natural bed than at
right angles to the bed.

If the pieces of rock so loosened from
their beds are too large to lift by hand or
by the crane power which is available, they

are broken by means of a sledge hammer or
P. mEED split by wedges, or by “ plug and feather.”

Plug

Feathers

Elevation.

Feathers The latter method is, as a rule, only adopted
when the rock is to be used for building

Bisa purposes, in which case care is necessary
Hie, di Wecavatingock to ensure that the blocks are regular in
by “‘ plug and feather.” shape.

 
PLANT USED IN EXECUTING EARTHWORK 79

The “ plug and feather ”’ (see Fig. 46) consists of a wedge-shaped
piece of steel, or plug, which is driven between two segmental-
shaped pieces of wrought iron or feathers. The holes in which the
feathers are placed are drilled by a chisel or small hand drill. The
plugs are driven in between the feathers alternately as in the case
of wedges until the rock splits along the line of the holes.

REMOVAL OF EXCAVATIONS BY MECHANICAL MEANS

Soft excavations—The expediency of removing earthwork by
mechanical means has already been referred to. Various machines
are in use for the removal of soft excavation, but for ordinary rail-
way work the principal one is the steam digger or shovel.

The primary requirement in a steam shovel is to have a machine
that will withstand a large amount of rough usage, and conse-
quently the working parts must be made of the toughest material.
In this connection cast steel is largely used. The design cf the
machine must also allow of a certain “‘ play” or freedom of action
which will take up the jolting or hammering without the parts
which must of necessity be close fitting being unnecessarily strained.

The various movements of a steam digger are very similar to
the movements of a man when excavating earth by hand labour.
The hand shovel is first lowered, then pressed into the ground, and
when filled it is raised, swung round and emptied into a barrow or
wagon.

In the case of the steam digger the bucket is first lowered into
the bottom of the cutting by releasing the lifting rope. It is then
pulled up, being at the same time pressed into the cutting, and
when filled, it is swung round and the excavations emptied into a
wagon.

RUSTON STEAM CRANE NAVVY

The Ruston steam crane navvy is the digger in general use in
Great Britain, and is typical of the best class of this machine.

In the earlier type of Ruston digger, the boiler and lifting gear
were fixed to the carriage in a similar manner to what is done
in the Ruston steam shovel, hereafter referred to, and could thus
only revolve through about 180 degrees ; but in the Ruston steam
80 EARTHWORK IN RAILWAY ENGINEERING

navvy or digger now in use the machine revolves through a com-
plete circle, thereby allowing of wagons being loaded immediately
in the rear of the machine.

There are several sizes of Ruston steam navvies, but the machine
most suitable for general railway excavation work is what is known
as the No. 12 machine (see Fig. 47).

The nett weight of this machine is 41 tons, and it will work
in a cutting 27 ft. deep without breaking down the top by hand.
On account of the long reach of the jib, the digger is able from one
position to excavate to a width of 42 ft. at the bottom of the cut
to 63 ft. at the top. This range of working allows of the excavated
material being loaded into wagons with less shunting and also of
the bucket being brought more directly over the wagons, thereby
reducing the labour in cleaning up material that may have dropped
over the sides of the wagons. The door of the bucket when open
will clear a height of 19 ft. above the level at which the digger is
placed and where the cutting does not exceed 10 ft. deep, or where
the cutting is in side-lying ground with the low side not more than
10 ft. deep, the excavations can be loaded into wagons placed on
a line of rails outwith the cutting, which may be a considerable
advantage in the removal of the excavations to embankment or
to spoil. ;

It is not proposed to enter into the mechanical details of con-
struction of the machine, but the following details should be noted.

The boiler is of the vertical cross tube type, and the water previous
to entering it is heated in a water heater by exhaust steam, this
resulting in a considerable saving of fuel.

The jib is constructed of steel plates and heavy angles, and
the bucket arm which consists of two oak beams, one on
each side of the jib, is heavily reinforced by mild steel plates so
as to withstand the heavy stresses to which it is subjected.

The stroke of the bucket arm is controlled by toothed gear fixed
to the jib, which engages with long steel racks fixed to the under-
side of the bucket arm, the toothed gear being operated by engines
mounted on the jib.

The bucket is heavily constructed of steel plates and angles and
fitted with a steel casting to receive the bucket arm. The teeth,
of which there are four, are carried about the full depth of the
bucket and consist of mild steel shanks with renewable manganese
si

PLANT USED IN EXECUTING EARTHWORK

  

‘AaveU OULIO TEs VOISNY—'/F ‘LT

E.R.E.—@
82 EARTHWORK IN RAILWAY ENGINEERING

steel points fitted on a renewable lip plate. The teeth are fitted to
the bucket plates with counter-sunk bolts, which allow of them
being quickly renewed.

The hoisting rope is double and the drum, which is of a large
diameter, has right- and left-hand grooves on it, so as to increase
the life of the rope and also equalize the pressure upon the drum
bearings and side frames.

The carriage of the digger is supported on two axles with wheels
to suit both the ordinary gauge of 4 ft. 84 in. and a gauge of 9 ft. 6 in.,
the narrow gauge being provided for the purpose of travelling the
digger from one section of the railway to another, while the broad
gauge wheels, which are provided with double flanges, are used
when the digger is in operation, thereby giving the machine a
broader working base.

In carrying out the work, when the bucket is lowered to the
bottom of the cut it is allowed to swing a little past the vertical,
and in doing so the catch of the door drops automatically into its
place. The bucket is then pulled up the face of the cutting, being
kept hard pressed into the cutting by the racking engine. After
it has reached the top of the cut, or if it is filled before it reaches
that height, it is pulled a little back from the cutting face and slued
round until it is over the muck wagons, and, when in proper position,
the door of the bucket is released by the man at the jib pulling a
cord which is attached to a link connected with the catch of the
door.

The bucket generally used with No. 12 machine has a capacity
of 2 cubic yards, which represents about 12 cubic yards of solid
excavation.

For heavy railway excavation work with large quantities of
material to remove, the Ruston No. 20 machine is well adapted.

The nett weight of this machine is 55 tons, and it will work
in a cutting 29 ft. deep without breaking down the top by hand.
The digger, from one position, will excavate to a width of 44 ft.
at the bottom of the cut to 72 ft. at the top. The bucket generally
used with this machine has a capacity of 2? cubic yards, represent-
ing about 24 cubic yards of solid excavation.

To allow sufficient space to operate these machines it is necessary
that the cutting should be not less than 30 ft. wide at the bottom,
so that in a single line cutting it is necessary that the level at which
PLANT USED IN EXECUTING EARTHWORK 83

the digger is operated should be about 3 or 4 ft. above formation
level of the railway.

As already stated, the output from a cutting which is being
excavated by means of a steam digger is largely controlled by the
facilities which exist for having the excavations removed, but with
a constant and uninterrupted supply of wagons for taking away the
material and with operations carried out under favourable con-
ditions the No. 12 Ruston navvy has excavated 350 cubic yards
of boulder clay and 800 to 1000 cubic yards of sand in a working
day of ten hours; while the No. 20 machine has excavated 550

 

 

 

 

Fig. 48.—Ruston steam crane navvy.

cubic yards in well blasted rock, and 1200 to 1400 cubic yards in
a chalk cutting during the same time. These figures would, of
course, require to be reduced to make allowance for bad weather
or other delays.

The relative output of the two sizes of machine referred to may
be said to be proportionate to the pressure of the teeth of the
bucket on the cutting face, which in the case of the No. 12 machine
is 12 tons, and in the case of the No. 20 machine 20 tons, and the
capacity of the lifting bucket is arranged accordingly.

By removing the bucket and bucket arm, the navvy can be
used as an ordinary steam crane, the lifting power of the cranes
being 12 tons and 20 tons respectively.
84 EARTHWORK IN RAILWAY ENGINEERING

The illustration (Fig. 48) shows the usefulness of the long racking
gear. It will be observed that five wagons were loaded from one
position of the digger.

WILSON STEAM CRANE NAVVY

The Wilson steam crane navvy, illustrated at Fig. 49, is also
largely used in Great Britain for the removal of earthwork.
So far as actual working results are concerned, the 12-ton Wilson

 

Fig. 49.—Wilson steam crane navvy.

navvy is very similar to the No. 12 Ruston navvy already referred
to, and is an equally serviceable machine.

Instead of the long bucket arm in the Ruston digger the Wilson
digger has a “luffing”’ jib, thereby lengthening the reach of the
bucket.

The special feature of this digger is the steam racking cylinder
which operates the bucket arm. The cylinder is bolted to the arm
and the arm is pivoted to the underside of the jib and radiates
therefrom. The bucket is fed up to its work by means of the
racking cylinder, and can be moved in or out a distance of 2 ft.
as desired.

The jib can be adjusted from a minimum radius of 16 ft. to a
maximum radius of 25 ft. The machine weighs in working order
43 tons,
PLANT USED IN EXECUTING EARTHWORK 85

Some of the machines of this type are provided with a bent
jib (see Fig. 50), the advantage of which is that it allows wagons
to be brought closer to the machine, thereby reducing the labour
in bringing forward the wagons.

This digger can conveniently work in a width of 25 ft. at forma-
tion level, and will reach to a width of 50 ft.

The bucket used for average material has a capacity of 24 cubic

 

 

 

 

 

 

 

ee

Fre. 50.—Wilson steam crane navvy (with bent jib).

yards, and can excavate a cutting 18 ft. deep without breaking

down the top by hand.
When used as a crane this steam navvy will lift a load of 12 tons

at a radius of 16 ft.

RUSTON STEAM SHOVEL

The Ruston steam shovel, illustrated at Fig. 51, is specially
made for dealing with heavy earthwork in large quantities, and
where the operations are not confined to the limits of an ordinary
railway cutting.

The nett weight of this machine is 78 tons, and it will excavate
a cutting 27 ft. deep with a maximum cutting radius of 32 ft.

The bucket has a capacity of 34 cubic yards.
86 EARTHWORK IN RAILWAY ENGINEERING

(The Engineer, 9th April, 1915).

Fia. 51.—Ruston steam shovel.

 
PLANT USED IN EXECUTING EARTHWORK 87

The larger output consequent on the more powerful description
of the machine commend it for specially heavy work.

LUBECKER LAND DREDGER

This digger machine has been extensively used in connection
with canal excavations and also to a limited extent in railway work
where a large quantity of soft material has to be removed.

The machine is built on the same principle as a marine dredger
(see Fig. 52), the excavations being removed by a series of buckets
attached to two endless chains. The machine is of two types,
to cut out the excavations either above or below the rail level on
which it travels.

It works on rails running parallel to the direction of the cutting,
advancing automatically on the rails as the work progresses, i.e.
as the chain of buckets projecting at the side excavates the soil and
throws it into trucks for transportation. The trucks stand behind
the excavator and at the «ame Jevel on which the machine is placed.

In order that the chain of buckets may be kept constantly in
use it is necessary that the rails on which the machine travels
should be shifted forward from behind the machine, this being done
after the machine has made one or several cuttings, and, so as not
to disturb the operations, there should be a length of railway equal
to from three to five times that of the train of wagons which is being
filled.

To prevent the sand or earth from falling between the trucks
the machine is provided with movable chutes, which may be
turned round so as to direct the material from one truck into the
next and prevent it falling on to the track.

ROCK EXCAVATIONS

Where rock is removed by blasting, the drill holes into which the
explosive agent is inserted may either be driven by hand or by
machine drills. Speaking generally, the harder the material and
the more difficult to drill by hand, the greater is the advantage of
machine drilling.

In open cuttings of railways there is generally a much larger
proportion of soft material than rock, for the reason already stated
88 EARTHWORK IN RAILWAY ENGINEERING

Fig. 52,.—Lubecker land dredger.

 
PLANT USED IN EXECUTING EARTHWORK 89

that the route can be chosen so as td avoid the more costly rock
excavations, consequently in general railway work the rock will
be in many cases removed by hand drilling.

HAND DRILLING

The bar used in drilling by hand is generally 6 or 7 ft. long and
about 14 in. in diameter, the point being chisel-shaped and about
1 in. wider than the body of the rod, so as to leave space for lifting
and lowering without any jamming of the hole. The hole is some-
times driven by “jumping” it, that is, by raising and dropping the
rod about 1 ft. 6 in. or 2 ft. at a time, two men being engaged in so
doing. After each blow the bar is turned slightly round in the
hole so as to ensure that the chisel edge will strike on a new
surface. Water is poured into the hole to keep the point of
the tool cool and also to soften the rock. The rock is ground into
dust or small chips, and the water “ cakes ” it, thus making it more
easy to remove when cleaning out the hole. It is necessary that
the hole be cleaned out frequently, as otherwise the broken material
will retard the drilling operations, and this is done by means of a
spoon-shaped scraper attached to the end of a thick wire.

The rate of progress of drilling rock by hand amounts to from
12 in. to 15 in. per hour, working in sandstone, limestone, or material
of a like nature ; but in whinstone or igneous rock the rate will not
exceed 6 in. to 8 in. per hour.

MACHINE DRILLING

There are two distinct types of machine drills, percussion drills
and rotary drills. In the former, the action may be said to be similar
to that which exists in hand drilling, the hole being formed by
repeated blows of a tool, but much more rapid than in hand drilling.
In the rotary drill, the hole is formed by the tool drilling out the
rock in a similar manner to the working of an auger in drilling wood.

The essential features of a good drill are that it should be of
light description and easy to move from one place to another,
simple in construction, avoiding complicated parts, thereby making
it more easily mastered by the men at hand, compact, so that
it can be used in restricted or confined situations, of perfect
90 EARTHWORK IN RAILWAY ENGINEERING

workmanship, and consisting of materials specially suited for the
particularly heavy work to which it is subjected.

Various types of percussion drills are made, but an example of
Ingersoll-Rand Company’s drill may be taken as typical of this
class of machinery (see Fig. 53).

In this drill, the rod, head, and chuck are all in one piece, whereas
if they had been constructed in separate pieces, there would have

 

Fig. 53.—Ingersoll-Rand rock drill.

been a great tendency for the parts to become loose with the shock
of 400 to 600 blows applied per minute.

In the best drills no cast iron is used, there being steel castings,
tooled steel, malleable iron, drop forgings, and special metal where
suited. The drilling tools are made of the best grade tooled steel
to cope with the very severe work to which they are put.

In the cylinder of the machine there is no cushion pressure to
retard the stroke and diminish the blow, and the blow is thus
PLANT USED IN EXECUTING EARTHWORK 91

absolutely ‘“‘ dead.”’ The drill has a wide variation of stroke, which
is secured by simply “cranking” the machine forward. This
has great advantage when driving a hole on an oblique surface,
and also admits of the hole being quickly started. The rotation
of the rod is effected by having spirally grooved rod or rifled recesses
in the back of the piston.

For the purpose of lengthening the bore as the work proceeds
each tool has a set of drills. A fresh tool is put on the end of the
piston rod as every few feet of depth are driven, and this allows of
the drill just removed being handed over to the blacksmith for
dressing.

Different types of drilling bits are in use for the various classes
of rock to be cut through. In sandstone, a flat blunt bit gives the
best result, while in an extremely hard rock, the X form gives
the best results. In rock of an irregular texture, and where it is
too hard for the flat bit, an X-shaped end is considered most
suitable, as the probability of rifling or grooving the hole is more
remote.

The best results in mechanical drills are secured with live active
air in preference to steam, but the particular situation and the
facilities obtainable will determine the method adopted. The
working parts are somewhat different in the air and steam operated
machines.

Where steam is used a considerable loss of power results if it is
necessary to have long lines of piping. In general, steam is probably
the most convenient and economical system, on account of the
expense in providing compressed air plant. In recent years elec-
tricity has been introduced to operate the compressed air plant,
and this is advantageous where long lengths of piping may be
objectionable.

Rotary drills have not found favour on public works, and they
are only mentioned here on account of the success which attended
the driving of the Simplon Tunnel. The machine which was used
there was worked by hydraulic power, the inventor and maker
being Mr. A. Brandt.

Hand hammer drills operated by compressed air have lately
been used (see Fig. 54). This machine was first used as a simple
means of drilling shallow blast holes in boulders too large for
removal by a steam digger or too heavy to be handled at a stone
92 EARTHWORK IN RAILWAY ENGINEERING

crusher ; but as no tripod or stand is necessary and as the hand
hammer drill is easily handled and moved about, and can be
operated in confined places where the tripod machine could not be
worked, it is now extensively used. The cutting tools are either
hollow, solid, or spiral-shaped. In hard solid rock where the
drills cut freely the hollow tool is used, and by passing the exhaust
air down the tube the debris at the foot of the holes is blown away

 

 

 

 

 

Fiq. 54.—Hand hammer drill.

from the cutting edge. In soft rock, a spiral steel is used, the spiral
acting as a conveyor for bringing the cuttings to the surface.
Solid cutting tools would be used for driving “ up-holes” where
the broken rock in the hole would fall out.

The time occupied in drilling operations varies considerably with
different classes of material. In granite the speed of drilling may
be about 2 ft. per hour, whereas the speed in sandstone or limestone
rock may be from 6 to 8 ft. per hour.
PLANT USED IN EXECUTING EARTHWORK 93

BLASTING

The explosive agent used in blasting is determined by the charac-
ter of the material to be dislodged, and whether it is proposed to
make use of it for building purposes.

If no use is to be made of the rock for building and the material
is being removed without any regard to the size or shape of the
blocks, a high-grade explosive would be used if the rock should be
of a tough description, such as whinstone or granite; but if the
material should be a sandstone or a limestone rock, and where
there is less resistance, a less virulent explosive would be more
effective. If the material should be boulder clay, as in the case
of breaking down a stiff cutting to feed a steam digger, the least
virulent explosive is used, namely, black blasting gunpowder, or a
low-grade granular nitro-glycerine. To get the best results, the
percussive force of the explosive should be proportionate to the
resistance of the material being removed.

If the rock has a commercial value and care has to be exercised
in its removal, small charges of gunpowder would be used, the object
being only to ‘‘ shake” the rock and lift it from its bed.

In firing the charge, if there are only a few shot-holes, a powder
fuse would be used; but if blasting is carried on extensively the
charges would be fired by an electric exploder. Reference is made
to the removal of rock in railway cuttings in Chapter IV, page 62.

CONVEYANCE OF EXCAVATIONS FROM CUTTINGS TO
EMBANKMENTS

The oldest and simplest method of taking earth in small quantities
short distances is by means of a wheelbarrow. The barrow in
general use is made of wood and has a capacity of about 4 cubic feet.
Barrows may be conveniently used where the distance to be carried
is less than about 150 ft., and to facilitate operations, planks of
timber, or barrow tracks, are laid down on which to travel.

Wheelbarrows are also made of iron, but the wooden barrow
is generally used on account of being more conveniently repaired.

Where excavations have to be taken for some distance over firm
ground, or along formed roads, horse carts are used. With fairly
good roads, a horse can drag a cart up an incline of 1 in 10 for

&
94 EARTHWORK IN RAILWAY ENGINEERING

short distances, and on a longer regular grade of about 1 in 12.
In the cart in general use, the shafts are in one piece with the body
of the cart, and to unload it the horse is detached from the shafts.
Carts for removing excavations are sometimes made with the
shafts and body in separate portions, thereby enabling the exca-
vated material to be emptied without detaching the horse from the
shafts.
The capacity of an ordinary cart is about 24 cubic feet.

TIP WAGONS

For taking excavations short distances, iron tip wagons, running
on a narrow-gauge railway, are sometimes used. These are of
various designs, but a very convenient type is that illustrated by

 

(6)

(a) Fic. 55.—Iron tip wagon.

Fig. 55. The usual size of this tip wagon has a capacity of 1 cubic
yard, and travels on light rails placed 2 ft. 6 in. apart. The under-
frame of the car is in a separate piece from the body and has vertical
frame supports at each end, on the sloping sides of which are jaws
which engage two pins fixed on each end of the box. The pins are
about 10 in. apart, and the box is held in position during transit
by means of a catch pin which locks the box with the carriage ; and
while there is no possibility of overturning during transit, very
little effort is required to tilt the box over and unload it.

It will be observed from Fig. 55 (b) that when the box is turned
over the sloping side is in such a position as to allow the material
to fall out without the assistance of any spade work. The wagon,
PLANT USED IN EXECUTING EARTHWORK 95

 

 

 

 

(©) Four cubic yards end tip wagon.

    
  

 

     

hi EE , Hite
I

od

=

Fic. 56.—End and side tip wagons.
(v) One cubic yard side tip wagon.
(qd) Four cubic yards side tip wagon.

 

 

(a) One cubic yard end tip wagon.

 

 
96 EARTHWORK IN RAILWAY ENGINEERING

when empty, is easily propelled along a level or up a flat
gradient by a man pushing it, and when full, a horse can
haul three or four wagons at a time along a level or up a
slightly rising gradient. This type of wagon is largely used in
countries where black or coolie labour is employed and where all
the work is done by manual labour.

Several types of iron box tip wagons of somewhat similar con-
struction to that above referred to are in use and are equally
serviceable.

For ordinary railway work, flat-bottomed wagons are generally
used. These are constructed both in wood and in iron, and are
of varying capacities (see Fig. 56).

Where the “lead” to embankment does not exceed half a mile
and where the material is being excavated by hand, l-yard wagons
running on a 3 ft. gauge railway are used. A rake of three loaded
wagons can be drawn by a horse up an easy gradient. If a light
engine is used for hauling the wagons more can be taken at one
time, and gradients, if they are of no great length, as steep as 1 in
30 can be negotiated.

If the distance to be hauled exceeds half a mile, or if a steam
digger is in use, larger wagons of, say, 4 cubic yards capacity,
running on the standard railway gauge, may be used, and these are
hauled by a locomotive. Wagons can be had with either side tip
or end tip action. The question of side tip as against end tip
wagons is referred to in Chapter IV, page 60.

Where excavated material has to be taken over existing lines of
railway in removing it from the cutting to embankment, it will be
conveyed in wagons provided with springs and buffers similar to
the rolling stock of the railway on which they have to travel.

DRAG AND WHEEL SCRAPERS

A method largely used in America for removing excavations
from railway cuttings in open country is by means of drag and
wheel scrapers.

The object of these machines is to remove the material from the
place of excavation, drag or wheel it to and tip it at the place of
embankment.

Previous to the material being conveyed from the cutting to
PLANT USED IN EXECUTING EARTHWORK 97

embankment the surface of the ground is, unless the material is
of a very loose description, broken up by a plough. In ordinary
earth the plough is hauled by two horses and two men are employed,
a driver and a ploughman. If the material is of a hard description,
the plough is weighted.

DRAG SCRAPER

For short leads of from 100 to 200 ft. a drag scraper is used.
The drag scraper, or ‘“ slusher”’ as it is sometimes called, consists
of a scoop-shaped iron box with a cutting edge, the capacity of it
being about 5 cubic feet.

Fixed near the front and to either side of the box by a
pivoted connection is a bent rod which forms an attachment
for a team of horses to drag the scraper over the ground, while at
the back there are handles to guide it when it is being filled and
emptied.

When it is desired to fill the box it is tilted up shghtly by raismg
the handles when being dragged along the ground. The sharp
edge cuts into the ground and the earth is scooped into the box.
On the handles being released the box takes up its original position,
and the box of earth is hauled to the tip. To empty it the driver
again lifts the handles and with the sharp edge cutting into the
ground the box is suddenly pulled up, which causes it to turn on
the pivots at the connection of the drag link, with the result that
the earth is thrown out.

A team of horses is required to haul the scraper, and the driver
usually empties it, other men being employed for the filling opera-
tion and also for the levelling of the ground at the tip. Where the
material is of a light description the driver of the team may also do
the filling.

WHEEL SCRAPER

Where the lead exceeds 200 ft. the wheel scraper, or “ wheeler,”
is used. The principle of it is the same as the drag scraper, but
being a larger box it is carried on wheels. By means of a lever
attachment the box can be tilted up to be filled or lowered as re-
quired. The average capacity of the box is about one-half cubic

E,R.E,—H
98 EARTHWORK IN RAILWAY ENGINEERING

yard. The wheel scraper is drawn by two horses, although it is
usual to employ another team, known as a snatch team, to assist in
filling the box. Where ordinary soil is being removed, it is usual
to employ one man extra to the driver, but in heavy soil it is
customary to employ two extra men for the purpose of filling.
CHAPTER VI

SLIPS IN EARTHWORK AND THE MEANS TAKEN
TO PREVENT THEM

THE importance of being fully informed as to the character of the
materials likely to be met with in executing earthwork, and the
necessity for thorough drainage works being provided have already
been referred to, but the bearing of these matters on the ultimate
success of the undertaking will be better appreciated when ques-
tions relating to slips have been considered.

CHARACTERISTICS OF VARIOUS MATERIALS

Slips in earthwork are due to the resistance between the particles
or between plane surfaces in contact having been overcome. The
tendency of all materials is to take up a horizontal position, and
the fact that one material will stand at a steeper slope than another
is due to that material having a greater frictional or cohesive
resistance. The slope at which a material will stand relative to
the horizontal is termed the angle of repose of that material.

Clean dry sand or gravel is supported by the frictional resistance
between the particles or stones, while, on the other hand, clay is
almost entirely supported by the cohesion of the mass.

A moderate amount of moisture or water helps to support earth-
work, but if there should be an excess of water the resistance to
movement is very considerably reduced. With a fine dry sand there
is no cohesion between the grains when in a perfectly dry state,
but with the presence of moisture or dampness cohesion is estab-
lished which enables the sand to stand at a steeper slope than it
would otherwise do. If there is an excess of wetness the sand will
not stand except at a very flat slope. The larger the particles or the
coarser the sand the steeper will be the slope at which the sand

will stand.
99
100 EARTHWORK IN RAILWAY ENGINEERING

In the case of clay, the presence of moisture very largely assists
the stability, but an excess of water will dissolve the clay and
destroy the supporting power. Pure clays are dangerous on account
of their stability being so much reduced by water. Certain clays
are so hard that they require a pick to excavate them, but after
continuous exposure to wet weather they get so soft that they
will only stand at a very flat slope.

The stability of a soil thus depends on the effectiveness of the
means taken to protect the material from or to remove any super-
fluous and consequently dangerous water. At the same time it
must be kept in view that all clayey soils require a limited quantity
of moisture for their stability, and that by exposure to the atmo-
sphere the moisture may get dried out and the supporting power
of the clay become reduced in consequence. The expansion of
clay when wet and the contraction in dry weather are also respon-
sible for considerable damage to earthwork.

The following are given as the slopes at which earthwork will
stand under ordinary conditions :—

Gravel . : ‘ ; . 1 horizontal to 1 vertical.
Dry sand : : : . sg 1 i
Compact earth. . ‘ 4 “4 1 be
Clay, well drained : . 5 1 3
Clay, wet : 2 . 38t0d5 Ks I a

In a rock cutting the slopes will range from } to 1 to 1 to 1,
depending on the character of the material. Certain material,
such as faikes or fireclay, may be very difficult to remove from a
cutting, but after weathering may require to be trimmed off to a
slope of 14 to 1.

The above figures should only be used as a guide, and in deter-
mining what slope the material will take regard must be had to
the actual conditions prevailing and the experience obtained under
similar circumstances, in view of the fact that the stability is so
much affected by atmospheric conditions and slight changes in
the character or composition of the material.

The character of the materials in the cuttings and the slopes
which it will be necessary to adopt as well as of the material to be
put into embankment should receive full consideration by the
Engineer as otherwise serious trouble may afterwards result. The
SLIPS IN EARTHWORK 101

possibility of flatter slopes being required than would at first sight
appear necessary should be fully considered before the construction
of the works is proceeded with.

SLIPS IN CUTTINGS

Ships in cuttings are either due to the action of water flowing
off the surface of the adjoining lands, water in the strata cut through,
to rainstorms or water in the form of moisture in the atmosphere,
or they may be due to the taking away of the natural support by
the removal of material which was necessary to maintain a state of
equilibrium.

As regards slips caused directly by the action of water, the

itch
Railway
Fence
itch

rs S%

; ee,
terceptin: &
FO eit ts g

drain

D

Fia. 57.—Drain for intercepting field
drains and surface water.

resulting damage may consist of the loosening and gradual crum-
bling away of the surface of the slope and the falling in of the portion
above for want of proper support. The water may have come
on to the slope on account of the surface or agricultural drainage
of the land not having been properly intercepted, or it may have
percolated through the strata. As already stated, the necessary
drainage of the adjoining lands should be executed prior to the
excavations in the cutting being proceeded with.

For the purpose of intercepting surface water it is usual to have
an open ditch cut on the high side of a cutting immediately outside
of the railway fence (see Fig. 57). If there are any agricultural
drains which would be interfered with in forming the railway cutting
these should be intercepted by laying a drain immediately outside
of the railway fence, which would either discharge into a pipe laid
down the slope of the cutting and connected with the drainage
of the formation of the railway, or be led entirely clear of the railway.
It is usual in laying this drain to leave the track which has been
102 EARTHWORK IN RAILWAY ENGINEERING

cut for it unfilled for the upper 9 inches, thereby forming a ditch
to catch the surface water. Agricultural drains will probably be
about 2 ft. or 2 ft. 6 in. below the surface, and the intercepting pipe
would be a 6-in. or 9-in. fireclay pipe with open joints, the joints being
surrounded by broken stones which would be carried up the trench
to within 9 inches of the surface. The agricultural drains would
be led into this main drain either by branches on the main drain or
by forming an opening in the upper surface of the pipe. If the
material in which the drains are laid is of a clayey description it
would be well to form the lower half of the joints of the intercepting
pipe with cement, so as to have a watertight channel, and thereby
prevent water finding its way into the slope of the cutting.

There is a danger of water from the surface of the adjoining land
which flows into an open ditch finding its way into the substrata,
and thereby causing damage to the slopes of the cutting. It is thus
necessary that consideration be given to the character of the
material in which any ditch or surface catch-water drain is being
formed, and if any danger is feared it is better that the surface
water should be allowed to flow freely down the slope of the cutting
into the formation drains. Where open ditches are formed they
should be periodically inspected and cleaned out, so that no damage
may result from obstruction.

If the water is coming through the strata it may have been
impossible to have known of its existence or to have made any
provision for its removal prior to the cutting being excavated,
but as soon as it is observed when the cutting is in progress
no time should be lost in dealing with it. The source of water
appearing in the cutting should be immediately investigated, and,
if it cannot be traced and intercepted either at its source or at
some distance from the cutting, the water should be conducted
clear of the excavation operations. In the event of water appearing
on the slope in small quantities or at a few isolated points, it may
only be necessary to lay rough stone pitching over small areas
and lead drains therefrom down to formation of the road or railway
cutting. An important point to observe is that when a drain is
laid to carry away water which may collect in stone pitching or in
dry filling it should be placed in the bottom of such pitching or dry
filling, and thus prevent damage by water collecting at a lower
level.
SLIPS IN EARTHWORK 103

Not infrequently springs are tapped in forming a cutting, and
these may be effectively dealt with by inserting a pipe in the slope
and leading the water to the surface, or if this is not sufficient, the
source of it may be traced by digging a trench and conducting the
water safely clear of the slope. No attempt should be made to dam
back or check the flow, or retard the free discharge of water appear-
ing in a cutting, as otherwise it is certain to break out at some other
point in a much more aggressive manner.

As a general rule the water would either be intercepted by laying
a drain at the level of the porous strata outside of and well clear
of the top of the slope of the cutting, or it would be allowed to come
to the face of the slope and be conducted by means of drains down
to formation level of the railway. To intercept the water before it
reached the slope might, unless the bottom level of the stratum
which contains the water is near the surface, prove to be very costly,
but if properly carried out it will be the more effective method, and,
keeping in view the future maintenance of the work, it will probably
prove the more economical in the end.

Where maintenance work of the description of keeping slope
drains in order is required, the subsequent remedial work to main-
tain them in a satisfactory state of repair is frequently delayed or
overlooked and indifferently executed, and it is thus better that
as little water as possible be allowed to percolate through to the
surface of the slope.

The water appearing in the strata may be traced to a natural de-
flection of the surface of the ground, and situated some distance from
the top of the slope, or the outcrop of the water-bearing stratum may
be ascertained from the inclination or “dip” as seen from the level of
the two sides of the cutting, and in either case, it may be much less
costly to lay a pipe to drain the natural hollow or intercept the water
in the stratum by a much shallower drain at some distance from
the cutting, than would be necessary if the drain were formed
immediately behind the top of the slope.

The following example will illustrate the manner in which work
of this description has been carried out. In taking out the exca-
vations of a railway goods yard, which was about 25 ft. deep, a
considerable volume of subsoil water was met with a few feet
below the surface of the ground. The material in the cutting
was of a fine sandy description with a proportion of clay mixed.
104 EARTHWORK IN RAILWAY ENGINEERING

with it, and as long as it was dry or contained only a small quantity
of water it was quite good for embankment purposes, but with the
large volume of water that was met with in the lower part of the
cutting it was rendered altogether unsuitable.

The material was being taken to an embankment about three
miles distant, and, on account of the water in the cutting, the
excavated material was converted into slurry, and the service
roads were very expensive to maintain in proper order by reason
of the drippings from the wagons, and the cost of tipping the
excavations at the embankment was also excessive. It was thus
necessary that the water should either be intercepted before it
reached the cutting face or that the material with the water in it
should be run to spoil embankment.

All the excavations from the line and station cuttings were
required for the purpose of making up the embankments, and,
if the material in question had not been available, side cutting
would have been necessary, and this would have entailed at least
double the cost in removal. It was therefore decided to intercept
the water before it got to the cutting, and this was done by laying
a drain below the level of the formation of the yard. In executing
the work it was necessary to close-timber the sides of the trench and
lay each pipe and form the joints under the constant inrush of water
and silty sand. All field drains cut through in laying the main drain
were connected to the main drain and the pipe was led to a proper
outfall. The joints of the pipes in the main drain were thoroughly
packed round by stones, and the trench up to the level of the water
in the stratum was also filled with broken stones. The result was
entirely satisfactory and the excavations were removed and de-
posited in embankment without further trouble.

In work of this description the most convenient drainage outlet
may be by a drain or several drains led down the slope of the
cutting which would discharge into a pipe laid along the formation
of the railway.

When the water in the stratum is allowed to come to the surface
of the slope (see Fig. 58) a complete system of drainage will be neces-
sary. Main drains would be laid square to the line of the cutting,
while diagonal and branch drains would connect with them as
shown. The size of these drains and the distance apart would
depend on the quantity of water to contend with and the character
SLIPS IN EARTHWORK 105

of the material in the excavations, but in ordinary circumstances
and with fairly solid material in which to form the drain, the main
drains would be placed from 20 to 30 ft. apart, and be 2 ft. wide
by 2 ft. deep, or deeper if necessary in order to get a grip of the firm
ground underneath.

The drain would consist of a pipe preferably with spigot and
faucet joints surrounded on both sides and on the top with broken
stone carefully hand packed in the trench. If the ground in which
the pipes are laid is of a clayey description the joints would be
formed as already described, with clay or cement for the lower

Surface of ground

 

. ¥ Y Y ¥
F — Slope Drains +
' ; 20,030" t ; i
! i i j '
\ '
, Pee eae
‘ fdemation Leval of Railway. L

 

Slope Drains discharge into. Fipe or Open Channel alongside Railway.
Fia. 58.—Slope drains in cutting.

half, so as to prevent leakage of water which would cause damage
to the ground underneath, and the trench would be made up on
both sides of the pipe to the same level as the clay or cement of
the joint, with clay well rammed in. In good ground, such as firm
sand or gravel, or with certain kinds of clay, where any little
leakage from the drain is not injurious to the slope, it would be
sufficient to lay an open-jointed tile drain surrounded by broken
stones, but in a soft material or material which is easily turned to
silt or slurry by the action of water, the method referred to would be
adopted.

It is necessary, in forming slope drains, that the drains and
broken stones be laid immediately after the track has been cut,
106 HARTHWORK IN RAILWAY ENGINEERING

as otherwise the sides of the track may fall in and seriously damage
the portions of the slopes on either side immediately adjoining.
In addition to taking away the water which appears on the slopes,
the drains so formed will be helpful in supporting the portion of the
slope between each of the main drains. These drains would, of
course, not be laid until the slopes of the cuttings had been formed,
but in view of the importance of keeping the embanking material
as free as possible from water, it is most essential that any water
met with should be temporarily led away in pipes or timber troughs
or other channels while the excavation work is in progress and
before any damage can result to the slopes.

When the slopes of the cuttings are subsequently being soiled,
care should be taken by covering the drains with bags or otherwise
to ensure that the soil is not allowed to mix with the broken
stones, and thereby reduce the efficiency of the drains, and for
the same reason the broken stones should be carried up to the
level of the surface after the slopes have been soiled.

In addition to the main and diagonal drains patches of pitching
may be necessary to drain any soft portion of the slope that may
have a tendency to slip. It is better that the diagonal drains
should not be laid with too flat an angle as there would be a
tendency for the soil on the upper side to choke the drain, and
there is also a liability for the drains to become distorted and
leak when any slight movement of the surface takes place,
thereby causing the material on the lower side to be washed away
and the drain ultimately to become destroyed for want of support.
A very satisfactory result, and that with little extra expense being
incurred, is obtained by placing a layer of turf along each side of
the drain and at the level of the soiling, the turf being held in posi-
tion by wooden pegs if there should be a tendency for it to slip on
the slope.

The slopes of a cutting are never thoroughly satisfactory until
they have been soiled over and sown down with grass and a good
tough sward formed. The roots not only form a binder to assist
in sustaining the material, but they are also a protection against
wind on a sandy surface, and against rain, which will damage a
clayey, sandy, or other surface, in which the material, when satur-
ated with water, has a tendency to “run.” If it is considered
necessary, stronger roots can be obtained by sowing the slopes
SLIPS IN EARTHWORK 107

with whin or broom seed, in which case a very firm deep-rooted
covering is obtained.

In the case of cuttings which consist of certain kinds of clay,
where the material, when protected, will stand at the usual slope
of 1§ to 1, what is wanted is more of a covering with close binding
roots, and where water falling on the surface will drain freely off,
and in such cases whin or broom would be objectionable. In sowing
slopes it is necessary that the work be executed at the proper
season of the year so as to ensure a good growth being formed
before wintry or otherwise inclement weather. To maintain the
slopes in good condition the grass or broom should be cut
periodically. While it is right that the slopes should be dressed to

Stone drains From
20'to 40 apart

 
 
 
   

Orystone Wal!

Fic. 59.—Large slope drains with toe wall at foot of slope.

a regular batter, it is a mistake to have too smooth a surface, as
the soil may get washed off by the first rainstorm and before the
roots of the grass covering are developed.

When the excavations consist of soft clay or other material
which, when in its natural moist condition may stand at a slope
of 3 horizontal to 1 vertical, but when saturated with water
may run to slurry, more expensive works than those referred to
will be necessary. The action of rainstorms on slopes of this
class of material, even after being covered over with grass, may
be most destructive. In dry weather the surface gets cracked and
open which gives access for water in wet weather, thereby causing
the damage. When adjoining property is valuable and where the
cutting is not more than a few feet deep, it may be more economical
to build retaining walls for the full depth of the cutting. If the
adjoining property is not expensive the material might be allowed
to take its own slope.
108 EARTHWORK IN RAILWAY ENGINEERING

If the cutting is over a few feet in depth, while the cost of the
land may not be of serious moment, to allow the material to adapt
itself to a natural slope might, owing to the configuration of the
ground, be entirely out of the question, and with the view to bring-
ing the work within reasonable limits it may be decided to drain
the slope in a somewhat similar manner to that already described,
but on a larger scale. Drains of from 4 to 6 ft. wide and from 2 to
3 ft. deep placed from 20 to 40 ft. apart would be constructed
(see Fig. 59) with a toe wall carried along the foot of the slope
continuous between the drains. The stones used for these drains
should be fairly large but not too heavy, otherwise the soft slope
would not be able to support them; but, on the other hand, they
should be such that the pressure of the material behind will not

    

2
(|
‘
'
‘
'
'
‘

Fia. 60.—Drystone dwarf wall at foot of slope.

force them out of place. If the clay from the cutting of the drains
is suitable, it would be burned and the clinker used for filling the
drains, or old slag ballast or other light material would be very
suitable. To protect the exposed clay from the effects of warm
weather and subsequent rains, it should be covered over with
ashes, gravel, or similar material to a depth of at least a foot, and
afterwards soiled over.

The method adopted for dealing with slipping material in clay
cuttings is largely determined by the cost of removing the material
and forming drains and revetment walls, together with the cost
of the land, as against the cost of building substantial retaining
walls.

In all cuttings through material other than rock the toe of the
slope alongside formation would be protected from erosion by water
flowing off the slope and running alongside formation. In very
SLIPS IN EARTHWORK 109

shallow cuttings a turf border 18 in. broad laid in two thicknesses
may be sufficient, but where over a few feet in depth it is usual to
form a drystone dwarf wall (see Fig. 60). The deeper the cutting
is the greater will be the volume of water running off the slope in
wet weather, and consequently there is the greater necessity for
the toe of the slope being well protected in deep cuttings. If a
wall is constructed ample provision should be made for the free
passage of water through it, and a drystone wall would thus be
preferable to a wall built with cement, where the wall is of a less
depth than 5 or 6 ft. Where the wall is built with cement a
thickness of 12 or 18 in. of drystone backing should be placed
behind it, with proper connections made to the drainage outlets
in the wall. These outlets or weep holes should not be more than

 

Fic. 61.—Flat slope in loose rock eutting.

about 9 in. below the finished level of the rails adjoining, so as to
ensure that there will be no obstruction at the outlet end of the
pipes.

Slips in rock cuttings are generally due to the inclination of the
beds of stratified rock whieh may be such that when cut through
the portion on the upper side of the “ dip”’ falls away for want of
proper support, and, if water should have found its way into the
strata, there will be the greater tendency to slip.

Slips are of most frequent occurrence in strata consisting of thin
layers of limestone or faikes intermixed with bands of clay or silt.
Overlying this there may be a porous stratum, from which water
finds its way through the fissures in the rock until a solid impervious
stratum is reached. When such material is cut through the water
will trickle down the face of the cutting over the exposed ends of
the strata, washing out the beds of clay or silt near the face, and
thereby undermining the thin layers of rock overhead, which will
ultimately fall in. Changes of weather, frost, thaw, and rain, will
110 EARTHWORK IN RAILWAY ENGINEERING

assist this disintegrating action. While the presence of water con-
siderably hastens the destruction, atmospheric influences alone
would slowly cause the exposed face to corrode, and unless other-
wise protected it would probably be necessary to take out the
excavations to a slope of 1} to 1 if the beds of the strata are level,
and if they should be at even a very slight inclination it may be
necessary to finish off the slope by stepping back the broken rock
to a batter of perhaps 24 to 3 to 1 (see Fig. 61). If it should be
necessary to flatten the slopes beyond what was originally intended
additional land will have to be acquired or face walls of sufficient
height built to keep the top of the slope within the limits of the
original ground. The method adopted will altogether be decided

sits

“Say Soi!

    
   
 

Brigh cope

Brick Facing with
concrete Filling
behind

Ditch .
Fic. 62.—Face wall in rock cutting.

on the question of expense, and in considering the matter it must
be kept in view that it will be less costly to maintain a retaining
wall than a slope which may require frequent attention.

When on account of the character of the material it is necessary
to excavate the rock to a 1 to 1 batter or to a flatter slope, a
covering of grass will prove a sufficient protection from the action
of the weather; but, if the material will stand at a steeper slope
without risk of sliding, a face wall would be constructed, ample
’ provision being, of course, made for free drainage of any water
that may collect at the back of the wall. Figs. 62 and 63 illustrate
a face wall and a retaining wall respectively to protect or support
a rock cutting.

As regards the treatment of slips, no hard and fast rule can be
laid down, as each failure must be dependent on the particular
SLIPS IN EARTHWORK ill

circumstances that surround it. By noting, however, the means
generally adopted and the manner in which special cases are dealt
with, a method of procedure may suggest itself.

When considering the means taken to prevent slips the necessity
for thorough drainage was pointed out, and the inefficiency of these
protective measures is very largely responsible for the slipping of
material in slopes. It will be obvious that by giving due considera-
tion to the question of drainage much of this trouble may be averted,
but it must be admitted that serious damage may occur by circum-
stances that could not have been foreseen. It is necessary to
emphasize the importance of frequent observations being taken if

   

Stone Facing with
concrete backing

  

Fia. 63.—Retaining wall in soft rock cutting.

there is any probability of a slip taking place, and when any water
appears or collects on the ground or when there is the slightest
indication of a movement in the ground, the warning should not
be neglected, but instant steps taken to avert what might mean
very serious trouble. These remarks apply equally to slips in
embankments as well as in cuttings.

When a slip does take place in a cutting endeavour should at once
be made to divert any water that may flow into the back of the
moving material, and such temporary work as the lightening of
the upper portion of the disturbed mass and the supporting of the
unmoved ground behind should also receive immediate attention.

When the damage done is of small dimension the slipped material
should be cleared out to the bottom (see Fig. 64), following on
which the surface underneath should be covered over with large
112. EARTHWORK IN RAILWAY ENGINEERING

stones, carefully hand placed, and a drain laid therefrom to the
ditch or water channel which runs along formation. Quarry
shivers or old slag should afterwards be placed on the top of this
layer of stones and brought up to the level of the surface of the
slope; the upper surface should thereafter be blinded with finer
material and finally soiled over and sown down. Care should be

Stone filling

   

Side drain
Fic. 64.—Slip of small dimensions in cutting.

taken to ensure that the stone filling is built close up to the back
of the slip, and any water in the exposed stratum should have free
drainage to the drain pipes leading to formation of the cutting.
Surface cracks which may subsequently appear, due to settlement
or after heavy rains, should be made good with a view to preventing
further damage. If the material under the slip is of a soft descrip-
tion, the filling in should be of a light character.

   

RICE WITLI TILE
Ee PAs PE ene eee re eee ry

Stone drain or counter fort drystone wall
6 ‘deep x 4 ‘wide, placed From 20°bo 50' apart.

Fia. 65.—Slip of large dimensions in cutting.

More extensive slips may be due to the complete saturation of the
materials in the slopes and the consequent tendency to take up a
horizontal position. In such cases an attempt should be made to
restore the material to its original stable condition by constructing
heavy slope drains and forming a strong toe wall in the manner
already referred to for dealing with soft cuttings. In certain
strata it is a common occurrence for the slipping material to come
away from the solid ground in a plumb face (see Fig. 65). The
SLIPS IN EARTHWORK 113

strata may consist of clay with thin layers of sand interspersed,
or it may be beds of limestone and faikes or clay in alternate
layers, and the movement will probably be caused by water perco-
lating through the sand or open joints of the broken rock, saturating
the clay bed and converting it into silt or slurry. Slips of this
description have been successfully treated by constructing stone
drains or counterfort drystone walls at right angles to the line
of the cutting. The trenches for the walls would be cut down to
and into the solid ground underneath and carried to the solid
ground at the back of the slip. These walls when formed will act
both as a carrier for the removal of water and as a support for the
unmoved ground behind. The width and distance apart of these
walls will depend on the character of the slipping material and the
depth of the slope; but in general they might be from 4 to 6 ft.
wide, and from 20 to 50 ft. apart. There is a danger of having
them too far apart, as each portion of the slope between the walls
may have a tendency to slip of itself. Surface diagonal slope drains,
2 or 3 ft. square, may be laid between the walls to consolidate the
ground more effectively and prevent further slipping; but if the
slope has been very badly shaken it may be necessary to turn over
the whole of the material between the walls and compact it by
wheeling and punning, and the surface should thereafter be covered
with a bed of ashes under the finished coating of soil, so as to
protect the clayey material underneath from the action of the
weather.

To further support the slope a drystone wall should be constructed
alongside formation, connecting the ends of the counterfort walls,
through which the drains from the slope would be carried into a
main drain laid alongside the track. If the excavations from the
drains should consist of suitable material it may be economical to
burn it into clinker for use in the walls and drains. In the event
of the damage being caused by surface water, a pipe would, as
already stated, be laid as soon as the slip is observed to divert the
water; but if the water is in the strata, it may be advisable to lay
a drain clear of the slip in addition to the other remedial work
referred to.

The following is an instance wherein circumstances necessitated
special treatment (see Fig. 66).

The cutting was for the construction of a railway and had a depth

E.R.E.—I
114. EARTHWORK IN RAILWAY ENGINEERING

of 29 ft. measured on the centre line ; but by reason of the inclina-
tion of the surface of the ground, which was about 44 horizontal to
1 vertical, the vertical depth from the top of the slope to formation
level was about 70 ft. The material cut through consisted of moss
for the first 5 ft., underneath which it was of a greasy clay until
formation was reached, when faiky fireclay was met with. The
material was being excavated to a slope of 1? horizontal to 1

|

 

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|

 

| Concrete bands
Xx 3°

|
ELL tS

Concrete Wall
pile in Sections

 

Ist

 

 

aot
ro ed ue ay

 

 

 

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Section AB.
Fie. 66.—Slip in cutting requiring special treatment

vertical, and the cutting had been excavated to within 5 ft. 6 in. of
the formation level, the slopes being dressed off to the finished batter
immediately behind the steam digger, when without any previous
warning the ground on the high side gave way. The plane on which
the mass of clay was sliding was inclined at about 23 to 1, and the
disturbed ground extended for a width of about 165 ft. outside of

the top of the slope.
Arrangements were at once made to remove the whole of the
SLIPS IN EARTHWORK 115

slipping material, and simultaneously a concrete wall was built in
trenches for the support of the lower portion of the cutting which
had not yet been removed. The wall was built in sections of 12-ft.
lengths and was carried on from both ends and at varying stages
of progress so as not to disturb the unmoved ground behind, and,
as a protection against the wall being pushed out after the lower
portion of the cutting had been removed, bands of concrete were
carried across formation to the foot of the opposite slope. After
the slipping material had been removed and the rough edges round
the slip dressed off to a regular slope, the area was soiled over
and sown down.

The following special measures were adopted in excavating a
railway cutting where a large volume of subsoil water was present,

 
     

noo +- = ,
12x6 Piling .
8! ae: ‘oe Slag ballast Stone Shivers

Fic. 67.—Section in cutting with large volume of subsoil water.

which will illustrate the means adopted to prevent subsequent
slipping (see Fig. 67).

The cutting was 43 ft. deep, and the stratum consisted of fine
sand and contained a large volume of water. As the work proceeded
the water in the sand was lowered until it reached a level of about
6 ft. above formation level of the railway, below which the material
consisted of fine sand and mud, of a very wet consistency. The
cutting was taken out to a depth of 2 {t. below formation level and
a row of sheet piling was driven along each side of formation.
These piles were 8 ft. long, 12 in. broad by 6 in. thick, and were
driven so that they would have 4 ft. of a hold below the level
excavated, and to allow of water getting through from behind,
a distance piece 4 in. thick was fixed to the side of each pile. The
space at the back was filled with stone quarry shivers and covered
over with ashes.
1146 EARTHWORK IN RAILWAY ENGINEERING

At certain points the flow of water in the sand behind the piles
was stronger than at others, and at these places open-jointed
fireclay pipes were laid and carefully surrounded with stones. The
space, which was taken out 2 ft. below the formation level between
the fronts of the two rows of piles, was filled up with ashes, and a
9-in. open-jointed pipe was laid along the front of the piling on
each side of the railway and covered over with broken stones.
The slag ballast of the railway was carried level across between
the piling and this assisted the keeping of it in position. The
slopes of the cutting were afterwards dressed and soiled and
sown down with grass seeds, a double turf cope being laid along
the top of the piling. As indicative of the quantity of water met
with, it may be remarked that each of the 9-in. pipes was running
half full for a considerable time after the work was executed.

SLIPS IN EMBANKMENTS

Slips in embankments are either due to the character of the
material of which the embankment consists or the condition of the
ground or of the substratum under the site of the embankment.

As regards the former, while the description of the material as it
appears in the cutting is the primary consideration, the manner
in which it has been removed from the cutting and deposited in the
embankment, together with the weather conditions when the work
was executed, may be very largely responsible for the stability of the
work.

From an economical point of view, it is generally desirable that
the quantities of the cuttings and embankments should as nearly
as possible balance, but an embankment must not be endangered
by depositing other than the most suitable materials, and conse-
quently all wet sand, mud, moss, or material of a similar description
should be run to spoil.

By reason of the fact that the cohesion of the material which
existed in the solid cutting has been largely reduced when the
excavations were being removed, the supporting power of the em-
banking material immediately after it has been deposited is for the
most part obtained from the frictional resistance between the
particles or pieces forming the mass. The original cohesive resist-
ance can, however, in a large measure be restored if care is taken
SLIPS IN EARTHWORK 117

in depositing the excavations in embankment ; but in view of the
vibration caused by suddenly applied loads such as occur on rail-
ways, it is not desirable to put too great reliance on the additional
stability so obtained.

In forming an embankment water should, as far as possible, be
kept clear of the operations in the cutting from whence the material
is obtained, and precautions should also be taken to prevent any
lodgment of water on the surface of the embankment. A good deal
depends on the time of the year when the work is being executed,
but neglect in making proper provisions for drainage is accountable
for many slips in embankments. A little rain will assist in con-
solidating an embankment, but a continuous spell of wet weather
will tend to cause slipping.

When operations are resumed after having been suspended on
account of inclement weather, clayey material which has been
converted into slurry at the poimt where excavations were pro-
ceeding, as well as similar material on the surface level of the
embankment where the excavations are being deposited, should
be removed and run to spoil. If the operations have been con-
ducted during a very dry season, moisture in the excavated material
will be dried out, with the result that when wet weather sets in
damage may be caused by reason of the swelling of the mass.
Sand or gravel, or similar material, will be much less affected than
clay, faikes, or material of a like description in which the particles
are dissolved by water. In clay embankments fissures and cracks
which are formed during a dry season should be filled up so as to
avoid damage when wet weather sets in.

When the excavations consist of hard clay, or boulder clay, it
may be advantageous to loosen it by blasting immediately ahead
of where the steam digger may be working, and there will probably
be large lumps of material which, if tipped into the embankment
without first having been broken up, will cause trouble, as surface
water will get into the crevices, the clay will soften, subsidence
take place, and finally a serious slip may result. When the material
is being deposited, the larger pieces of it roll to the bottom of the
slope, and if these should consist of large stones or pieces of rock
they will assist in maintaining the toe of the slope; but if they
should be pieces of clay, instead of acting as a support they will
cause serious trouble.
118 EARTHWORK IN RAILWAY ENGINEERING

Embankments of earth should be as homogeneous as possible,
and this is best obtained by bringing them up in several layers
when they are being formed in the manner already described.
The advantage to be gained in using side-tip wagons in prefer-
ence to end-tip wagons in forming wide embankments has already
been referred to. A method which has been successfully adopted
in constructing wide banks is to tip a narrow bank of good
material at the extreme outsides and afterwards fill in the centre
portion with whatever material was available; but this departure
from the recognised principle of running bad material to spoil
should only be resorted to when suitable embanking material cannot
otherwise be obtained.

When various classes of material are put into the same embank-
ment, or when the work is carried on during different kinds of
weather, some parts of the embankment will be more compact than
others, and consequently there will be a want of proper homo-
‘geneity, with the result that there will be a tendency to slip. It
may be very difficult to obtain the same material to fill a large
embankment throughout. Several cuttings may be required to
make up one embankment, and even the material in a large cutting
may vary considerably at different points, but if it is carried up
in layers, thus ensuring that each layer consists of the same material
or is executed during the same season, there will be less chance
of damage from that cause.

It is essential that the slope of the embanking material be not
made steeper than the slope to which the cutting from which the
material has been removed has been formed, and it is also necessary
that the slope should be sufficiently spread out so that the unit
pressure at the base, both on the material in the embankment and
on the ground on which the embankment rests, will not be too great.
It will be recognised, however, that it may be harmful to make a
slope too flat, for the reason that a larger surface is thereby ex-
posed, and also that by reason of inequalities in the surface which
occur in any slope and cause saturation of the material. It is usual
in high embankments to form the upper part with a steeper slope
than the portion nearer the base, and this is especially desirable
in a bank of clay. It has to be kept in view that the material in
any embankment is not absolutely compact until several years
have elapsed from the time of it being deposited.
SLIPS IN EARTHWORK 119

In order that a good toe be formed along the foot of the slope,
the more solid materials in the cuttings should be deposited along
the outer edge, and it is usual to strip the soil from off the area to
be covered and lay it temporarily along and outside of the foot of the
slope, where it will form a barrier for the deposited material and
at the same time be conveniently situated for the subsequent
soiling of the embankment. On side-lying ground it is desirable
that a trench be cut in the solid ground along the foot of the slope
against which the deposited material of the embankment will abut,
and it is also necessary that longitudinal trenches be cut at intervals
as has already been described, for the purpose of preventing slipping
of the material; but any trenches so formed should not be exe-
cuted for any lengthened period previous to the embanking material
being deposited, as otherwise if wet weather intervenes the base
of the embankments will be weakened rather than strengthened.
The importance of taking away water from the foot of a slope
and thereby ensuring the stability of the embankment at its most
vulnerable point will be appreciated.

As in the case of cuttings, the formation of a good sward of grass
is most effective in preventing damage by the percolation of rain
or surface water, or by the action of wind on a newly formed
slope, and no time should be lost in having the slope soiled. An
embankment formed of clay can never be considered satisfactory
until a good growth of grass covers the surface. In the case of
sand or gravel water will pass through and drain itself off, but in
the case of clay the water is retained and the clay will take a flat
slope. A layer of good turf along the top of a slope will form a
protection against the upper portion being damaged by the action
of rain on a bank which has been recently soiled. While it is
undesirable that the slopes of a high embankment should be soiled
until it has been raised to the full height, it is better that they
should at least be roughly dressed off to the finished batter as the
work proceeds, and this is more especially necessary in the case of
a clay embankment.

The upper surface of an embankment should also be impervious
to water, and this is well obtained by the constant traffic which
passes over it while the work is in progress, and as a precaution
against water getting into the bank from the top the upper layer
should consist of the more compact materials from the excavations,
120 HARTHWORK IN RAILWAY ENGINEERING

and so that there will be no lodgment of water on the surface it
should be finished off with a slight cross-fall from the centre to each
side. In the interest of the stability of an embankment for a rail-
way it is not desirable to make the formation too narrow so that
there will be the less tendency for the top of the slopes to give
way by reason of the traffic. When any settlement takes place after
heavy rain or frost or thaw, any crevices that may be formed should
be immediately restored with impermeable material.

While slips in an embankment, due to the material of which
it consists, can in a large measure be prevented if proper pro-
visions are taken, those due to the character of the ground on which
the embankment rests are much less easily obviated. The site of
the embankment may consist of moss, soft clay, or other similar
material, and any weight brought on to it will tend to displace
this material. When this soft stratum is of no great depth and
the surface of it is level, or nearly so, no damage will result beyond
the displacement of the surface, and the embanking material will
soon find its bearing on the solid ground underneath ; but if water
should be present in the soft material, as will probably be the case,
constant trouble may result if the ground has not been drained
prior to the embankment being proceeded with. Any water on
the site will cause the embanking material to spread out to a flat
slope, and if clay or other similar material is deposited it will be
turned into slurry, thereby causing a slip. The material on the
site may be such (as in the case of some clays) that no amount of
drainage will make it suitable for carrying an embankment, in
which case it will either be necessary to drive sheet piling along the
toe of the slope to prevent it spreading, or to excavate the material
from under the site of the embankment and run it to spoil.

Where piling has been driven the pressure of the substratum has
been known to shear off the piles at the level of the solid ground and
carry them bodily forward for a considerable distance. The removal
of the bad material to spoil will probably be an expensive operation,
but it will certainly be the more effectual. In certain situations
it may be impossible to thoroughly drain the site, and in such cases
by depositing ashes, old slag, gravel, or other material that will
not “run” on the top of the soft material on the site, the latter
can be displaced and a solid foundation obtained, and, after the
ashes or other materials have been raised to the level of the
SLIPS IN EARTHWORK 121

original surface, the ordinary excavations from the cutting can be
deposited.

In the event of the site being drained, the drains should be of
a massive description and be laid either in diagonal trenches or
square to the line of the bank, having an outlet into main drains
formed along the outside of the slopes. These drains will be carried
down to the solid ground, and those along the foot of the slopes
will be of such dimensions as would also act as a retaining wall
against which the embankment would abut. The material from
the excavation of the drains could, if suitable, be burned into
clinker and used for the drystone filling of the drains. If the
depth of the soft strata on the site is such as to preclude the possi-
bility of thorough drainage, the embankment would require to be

     
  
 

Railway
Embankment

is
Trenches filled with
stone 6 ft. wide at
60 ft. apart

 

   

Fia. 68.—Slip in embankment on side-lying ground.

supported on fascines, as has already been described in connection
with embanking over moss land. While the surface of the moss
or soft material may be level, the firm ground underneath may
be lying at an angle, and unless proper provision, such as has
been referred to, is carried out serious slipping may result.

The embankment may require to be formed on side-lying ground
of such a character that the material under the surface is in a state
bordering on motion, and when any additional weight is applied
slipping will take place. The unstable description of the ground
may be due to the presence of water in the material lying under the
surface, or to water acting on a greasy bed underneath, and the
drainage of the site or the interception of the drainage from the
adjoining land may be effective in converting the site into a good
condition.
122. EARTHWORK IN RAILWAY ENGINEERING

The following example will illustrate this point (Fig. 68). The
ground on which the embankment was to be formed showed signs
of slipping having taken place at a former period, and the stratum
under the surface was of a very soft character and side-lying at an
inclination of about 23 horizontal to 1 vertical. Trenches 6 ft. wide
were cut on the side-lying ground at right angles to the line of the
railway at intervals of 50 ft., and were carried down to the solid
ground underneath, which, in some places, was at a depth of 20 ft.
below the original surface, these trenches being afterwards filled with
large stones. Between these drains benches of 4 ft. wide by 3 ft.
deep were cut at intervals on the sloping ground parallel to the line
of the railway, and a heavy retaining wall was also built along the
foot of the embankment, which, in addition to supporting the slope,
acted as a training wall for the adjoining river. The excavated
material from the line cutting was then deposited in regular layers
and thoroughly consolidated between the drains and behind the
walls.

In such cases as that last referred to, where there is a solid stratum
of either rock or good material under the slipping material, it may
be more economical to construct retaining walls alongside forma-
tion to support the railway, or it may be considered better to carry
the railway on a series of arches. By adopting either of these
expedients, the first cost may be more, but by reason of the subse-
quent maintenance of the earth slope being avoided the alternative
schemes may be justifiable.

When an embankment is being formed on good ground a thorough
examination of the surface should be made so as to ensure that there
is no water coming to the surface from natural springs or drains
which have not been properly intercepted. Any water that does
appear should, if possible, be caught up outside the embankment
slopes, but failing this it should be conducted by iron pipes or
built conduits entirely clear of the operations. If the ground is
side-lying, water may be percolating from the outcrop of a stratum,
and it should be intercepted by a drain outwith the embankment,
in a manner similar to what has already been described in connec-
tion with the protection of cuttings.

The following example will illustrate this point (see Fig. 69) :—

The stratum immediately underneath the surface soil was of
a gravelly description, while underneath the gravel was clay at
123

SLIPS IN EARTHWORK

varying depths. The water in the gravel was held up by the clay

and made its appearance on the surface of the ground on which

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124 HARTHWORK IN RAILWAY ENGINEERING

side of the railway. The drain was in some places at a depth of
about 25 ft. A pipe was laid in the bottom immediately on the
top of the clay, the joints being left open and carefully packed
round with broken stones. The trench was filled to the surface
with stones, and all field drains intercepted were connected to this
main drain. Owing to the irregular line between the gravel and
the clay there had to be two outlets, one running parallel to the
railway, the other carried underneath the embankment on the side-
lying ground.

This latter drain consisted of cast-iron pipes supported with
concrete blocks at the joints. A heavy retaining wall was built
along the foot of the slope, and benches were cut in the side-lying
ground, after which the embankment was formed. When the
embankment had been brought to the full height, some water,
which had not been diverted into the intercepting drain, appeared
at places on the surface of the slope, and several minor slips took
place. Four drains 7 ft. wide by 7 ft. deep were then carried
up the slope of the embankment at intervals of about 30 ft. and
filled with heavy stones to the surface, and the slopes were
thereafter soiled and sown with grass seed and mixed with
broom. A good sward was soon grown, and no further trouble
was experienced.

In the construction of a railway or road in side-lying ground
where the earthwork is partly in cutting and partly in embankment,
great care should be observed to see that water from the cutting
on the upper side should not be allowed to percolate under the
embankment on the lower side, and it is necessary that the drainage
of the adjoining land, as well as the drainage of the slopes of the
cutting, should be properly attended to.

The remedial work required in the event of a slip in an embank-
ment due to the material of which it is constructed consists of the
removal of the water which has been the cause of the damage or
the supporting of the slope in a manner somewhat similar to what
has been described when referring to slips in cuttings. In an
embankment, however, operations are not so restricted at the foot
of a slope as they are along the formation line of a road or railway
when the construction is in cutting, and it is thus unnecessary to
remove the slipped material from the foot of the slope unless it is
encroaching on adjoining property.
SLIPS IN EARTHWORK 125

Surface slope drains or drystone counterfort walls carried down
to the solid and a good strong toe wall built along the foot of the
slope should be constructed as required. It is better that the
slipped material should not be removed, but be allowed to remain
at the angle of repose that it has taken, and if there should
be intrusion on adjacent lands a wall may be required to support
the lower portion of the slope or additional property may be neces-
sary. Serious slipping in an embankment has been effectively
stopped by loading the toe with heavy stones, thus arresting the
outward movement.

Water getting into the heart of an embankment has frequently
taken place by reason of fissures in the upper surface; this may
be the cause of periodical slipping and will give constant trouble
unless it is effectively dealt with. In such a case a drainage heading
or series of drains driven into the bank would remove any water
which had collected or was in the material, and it would also be
necessary to remove part of the upper surface of the embankment
and replace it by good material.

A case is reported where a bank 60 ft. high, formed of dry sand
and gravel slipped by water appearing on the surface of the slope.
The ballast and permanent way of the railway had been laid and,
when investigation was made, the damage was traced to the manner
in which the surface of the embankment had been executed. The
formation of the railway had been formed to the usual cross-fall
for the purpose of draining off surface water, but the subsequent
settlement of the embankment necessitated a greater depth of
ballast being laid to bring the railway to proper level. For the
sake of appearance the bench between the foot of the ballast and
the top of the slope on either side has been made up with slag
riddlings, which prevented the free drainage of the surface of
formation, with the result that instead of the water running off
the slopes it was held in a hollow under the rails, thereby finding
its way into the sand and gravel and causing the slip.

Embankments have been known to slip after a number of years
through water, which had no means of escape, having collected in
the heart of the bank, and on a drain being formed to the seat of
the trouble the water found an outlet and the slipping ceased.

Slips due to bad material being deposited in embankment are
sometimes very troublesome, and there are cases on record where
126 EARTHWORK IN RAILWAY ENGINEERING

an entire bank has had to be removed and run to spoil. The
material of which it was constructed appeared to be quite good
when deposited, but after wet weather set in it was converted into
slurry.

If the slip should be due to unequal settlement of the embanking
material, the fissures which are formed on the surface should be
closed up, otherwise the embankment may be completely rent in
two. In such cases, after settlement has taken place, the upper
portion of the embankment for several feet in depth should be
removed for the full width, both of the stable and unstable material,
and the bank thereafter brought up to its original level by means
of ashes or other dry material, so as to ensure that any load after-
wards applied to the upper surface will be equally distributed over
both parts of the embankment underneath. When the site of the
embankment is unsatisfactory and the preventive measures already
suggested have either failed or have not been properly executed,
serious slipping may result. Embankments have been known to
move for many years after they were constructed, in some cases
leading to their ultimate abandonment.
CHAPTER VII
MAINTENANCE OF EARTHWORK

THe more thoroughly the work of constructing the railway is
carried out the less will be the subsequent cost of maintenance.

In the preceding chapter the means taken to prevent and remedy
slips were considered. It was pointed out that the greater number
of slips were due to the presence of water, and the necessity for
diverting water away from cuttings and embankments, or of leading
it away in such a manner as would prevent damage, was emphasised.
It is necessary, however, that these preventive and protective
measures should be kept under constant observation, and that
so soon as any interruption of the functions for which these special
works were carried out is observed, immediate steps be taken
to remedy matters.

The maintenance of railway works is always greater the first
year or two after the works are completed than during subsequent
years.

Special inspection should be made of cuttings and embankments,
more especially the drainage works, during wet weather or after
periods of melting snow or abnormal discharge from water-bearing
strata, when the various drainage works will be fully taxed, and
this inspection should be carried out in a most thorough manner,
so as to ascertain what, if any, additional works are necessary and
what repairs require to be executed. In the case of open ditches
it will at once be seen where there is any interruption of the regular
flow, and the ditch can be cleaned out; but in the case of pipe
drains, or piping laid in the bottom of stone pitching (or “ beach-
ing”), an obstruction may not be detected until there is indica-
tion of such on the surface, either in the form of a discharge of
water or by damage to the slope or surface of the ground.

The maintenance of the permanent way in first-class condition

127
EARTHWORK IN RAILWAY ENGINEERING

128

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MAINTENANCE OF EARTHWORK 129

is one of the principal duties of the Engineer, and to obtain the best
results perfect drainage of the formation is essential.

Water falling on the railway or draining on to it should be
removed as speedily as possible, and the railway works should be
designed with this in view. The surface of the formation in both
cuttings and embankments should have a camber or cross-fall
from the centre to the sides so that water passing through the
ballast will be shed off, and in cuttings side drains or open ditches
should be provided for the removal of water both from the forma-
tion and from the railway slopes. Fig. 70 shows typical cross-
sections of British main line permanent way.

The ballast under the sleepers is regarded as the foundation of
the permanent way; but the real foundation is the material on
which the ballast rests, and if it is unsatisfactory the whole object
of having good ballast is defeated. A good foundation under the
ballast is of equal importance to the ballast itself. It is thus
necessary that the material immediately under the ballast he kept
thoroughly drained, and this is effected by side drains or open
ditches.

If water is allowed to collect under the sleepers, or if the material
under the sleepers retains water, the soft wet material will very soon
be converted into mud, and will be squeezed through the ballast.
The result will be that the life of the sleepers will be very con-
siderably reduced, the fastening of the chairs to the sleepers will
be rendered ineffective in a short time, and the permanent way
generally will be seriously impaired.

The material under formation may be of such a description that
it cannot be drained, and any water passing through the ballast
into it converts it at once into slurry. In this case it will be better
to remove such material to a depth of 2 or 3 ft., or deeper if neces-
sary, and replace it by old slag or spent ballast, ashes, or other
material that will not obstruct the drainage.

So far as the ballast of the permanent way is concerned it should
consist of good hard slag, broken whinstone, granite, or other
material which will permit of free drainage, and at the same time
give a solid bed for the sleepers.

Good drainage and good ballast are essentially necessary for
first-class permanent way.

Reference was made in the previous chapter to the damage done

E.R. E.—K
130 EARTHWORK IN RAILWAY ENGINEERING

by making up the sides of an embankment—where additional
ballast was necessary to bring the railway to proper level—with
earthy material so as to have a neat and tidy appearance, with
the result that instead of having a fall from the centre to the sides,
there was actually a water channel down the centre of the railway,
which ultimately found an outlet on the face of the embankment
and caused a slip. It would have been better to have left the edges
of formation low, although they might have had a slightly ragged
appearance, rather than interrupt the free drainage of the formation.
Neatness in maintaining the railway is an indication that the work
is also being efficiently executed, but if those who are responsible
for the maintenance of the permanent way do not thoroughly
appreciate the importance of good drainage, their efforts in
maintaining a neat formation will be entirely ineffective.

The object, so far as the drainage and width of a cutting are
concerned, is to bring the condition of the roadway as near as
possible to what exists in an embankment where there is free
drainage and the railway is in the open.

The formation of a railway in cutting should be as wide as possible,
so as to obtain proper drainage, and also to get the benefit of the
drying effect of wind and sunshine. It is a mistaken policy to cut
down the width of formation at the expense of the maintenance.
This matter has already been referred to in Chapter I, page 4.

For the drainage of cuttings an open channel is preferable to a
closed pipe, as it can be easily cleared of any obstruction. When
the gradient of the railway is flat and the flow of water sluggish,
an open channel is easily obstructed by debris, leaves of trees,
washings off the slopes, and stones from the ballast, and any
interruption of the flow will tend to weaken the support of the
ground under the sleepers, and also to undermine the foot of the
slope of the cutting. For this reason, a pipe would be used in
preference to an open channel on a flat gradient. Apart from the
question of the gradient, it may not be possible to construct an
open channel on account of the soft description of the material, in
which case a pipe would be laid.

When a ditch or open channel is provided it should be formed
along the foot of the slope, one side of the channel being the toe of
the slope. The channel would be about 1 ft. to 1 ft. 6 in. wide by
6 to 9 in. deep. If the material in the bottom of the cutting is
MAINTENANCE OF EARTHWORK 131

of a firm description the sides would be able to support themselves ;
but, so as to form a toe for the bottom of the slope of the cutting,
a 12-in. depth of stone pitching, with a double layer of turf 1 ft. 6 in.
broad laid on the top, should be placed alongside the channel.
Where the material is unstable, the channel would be lined with
stones on both sides. In the case of cuttings over 15 or 20 ft. deep
where a large volume of water may have to be dealt with, it is
usual to have a low drystone wall along the foot of the slope, with
the channel formed immediately in front.

When, instead of an open ditch, a pipe is laid alongside formation,
the top of it should not be less than 9 ins. below formation, and
so that there will be free drainage into it, and that no water will get
out of it to the damage of the ground underneath, the joints should
be cemented or formed with puddle clay to the level of the horizontal
diameter, while the upper half of the joints should be left open. The
filling in of the trench should be carefully and firmly packed up to
the same level as the sealed half of the joints of the pipes with
clayey material. Above this level the joints should be carefully
surrounded with broken stones and the trench filled to formation
level with broken stones. The upper surface at formation level
should be finished off with slag, or broken stone screenings, thereby
ensuring that any water running off the permanent way or off the
slopes will drain into the pipes. The pipe gratings should be placed
at intervals along the edge of formation. Inspection chambers
should also be provided on the line of the pipe at intervals of
about 80 yards, and to allow for any stoppage in the flow of the
pipe cross pipes connecting both sides of formation should be laid
at every second or third inspection chamber.

It should be kept in view that the drainage works in a cutting
are as much for the purpose of keeping the material under the
tailway in a good condition as for the removal of water which falls
on the surface.

It is very important that the slope of the open channels or pipes
in a cutting should be as steep as possible as, if the water which has
been collected into them is not expeditiously removed, considerable
damage may result. In long cuttings the water-course may be made
slightly steeper than the railway cutting on one side of formation,
and connected at intervals by cross pipes to the drain at the foot
of the opposite slope. Connections should be made to the nearest
132 EARTHWORK IN RAILWAY ENGINEERING

outlet, and the water conveyed in properly formed ditches or in
pipes entirely clear of the railway embankment. If it is merely
allowed to discharge on to the ground and run along the foot of the
embankment serious damage may result by eating away the toe
of the slope, or what may be very much worse, the water may
find its way underneath the embankment.

For the purpose of obtaining a fall for drainage, it is better
that the railway in cutting should be constructed on a gradient.

The Pennsylvania Railroad Company, America, has given con-
siderable attention to the question of maintaining the road-bed at
high standard. A part section of their cutting is shown at Fig. 71.
The distance from the outer edge of the ballast to the foot of the
slope is 5 ft. 6 in., and the side ditch is formed by having an even
fall from the ballast to the foot of the slope of the cutting, the

 

 

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50

  

Fic. 71.—Part cross section of Pennsylvania railroad, America,

bottom of the ditch being 1 ft. 5 in. below the bottom of the ballast
at the edge. The slopes are protected from erosion by being turfed,
and, where necessary, drystone toe walls are built. With so
great a distance from the ballast to the foot of the slope, no damage
results to the ballast even with the railway on a very flat gradient.
The whole object of the greater width is to obtain good drainage,
with a view to keeping down the cost of maintenance. The
cost of maintenance is, no doubt, considerably reduced, but the
extra cost of construction is great. The cost of the additional land
required for the greater width has also to be considered.
Reference has been made to the importance of having a good
sward of grass on the slopes of cuttings and embankments. Having
got this, it is necessary that it be kept in good condition by having
it regularly cut or burned. In open country where passing through
agricultural land, it is a common practice to let the adjoining
farmers have the grass off the slopes for a nominal rent, conditionally
that they keep the slopes regularly cut. Where the Railway Com-
pany’s own men attend to the slopes it is usual to burn the grass,
MAINTENANCE OF EARTHWORK 133

and this, while keeping the grass short, also provides a manure
which strengthens the roots.

The ends of all culverts should be regularly cleared of all debris,
branches of trees or other material which may have collected in
the culverts, and which cause stoppage or interruption to the
regular flow of the stream.

To protect the railway where in cutting from being blocked by
snow drifts it is usual to erect sleeper fencing on one or both sides
of the line where considered necessary. An additional line of
sleepers placed about 15 ft. distant would be a further protection.

In countries subject to very heavy falls of snow endeavour is
made to have the line of railway altogether in embankment, but
where cuttings are unavoidable it is usual to protect the line of
railway from being blocked by having snow sheds erected where
the blocks are likely to take place. These sheds consist of open
framework covered over either with wood or corrugated iron
sheeting.

In rock cuttings where stones are likely to become detached by
reason of frost and subsequent thaw and which would cause an
obstruction to the railway traffic, an arrangement has been success-
fully adopted whereby engine drivers are warned of an obstruction.
A series of wires on telegraph poles is carried along the side of the
railway adjoiming the cutting, and connected with a signal on
the railway which normally stands at “ clear,’ and in the event
of the wires being broken by falling rock the signal at once rises to
“ danger.”
CHAPTER VIII
CONDITIONS AFFECTING THE COST OF EARTHWORK

In Chapter I reference was made to the various matters to
be considered when preparing the estimate of cost of an earth-
work undertaking. It is now proposed to discuss in some detail
the points which affect the actual expenditure in the practical
work involved. These vary very considerably under different con-
ditions; but, briefly stated, they are :—

(1) The cost of labour.

(2) The character of the materials to be excavated.

(3) The facilities for removal of the excavations or convenience
in obtaining the embanking material.

(4) The prevailing weather conditions when the work is in progress
and the time within which the work is to be executed.

It may appear superfluous to state that the financial success of
an earthwork undertaking very largely depends upon the efficiency
of the control of the operations. So much, however, attaches to
the management that it is necessary to emphasize this point. A
thorough knowledge of how to make the very most out of a job
can only be obtained by a close acquaintance with constructional
work and this, along with the qualification of handling men and
a quick and clear appreciation of the difficulties and emergencies
attendant on such work, combine to form the superintendence which
is essential for obtaining the best results.

The cost of the work can very materially be reduced by having
skilful, resourceful, and experienced men in charge. These remarks
apply equally to the manager, foremen, and gangers in charge of
the various squads of men distributed over the work. This is
specially necessary in the construction of earthwork on which
the men engaged are for the most part drawn from unskilled
labour.

134
CONDITIONS AFFECTING THE COST 135

When large numbers of men are engaged and are exposed to
changeable weather, working frequently under most adverse con-
ditions, the proper housing of them is an important consideration.
Attention to their personal comforts will more than anything else
create a good feeling, with correspondingly satisfactory results in
the execution of the work.

With a view to expediting the output from cuttings or the form-
ing of embankments the Contractor may find it convenient to
encourage the “‘ gangers” who are in charge by paying them
bonuses on results, after the number of wagons or cubic yards
handled per diem exceeds a certain number. A similar object is
attained by sub-letting the labour to the “ ganger,” thus giving
him a financial interest, however small, in the work.

The contractor will find it to his advantage to have a systematic
cost made every week or fortnight throughout the whole course
of the operations, from which he will see whether the work is being
profitably and economically executed.

For this purpose he should have a costing Engineer, whose duties
will be to calculate the quantities of the several items of work and
collaborate with the timekeeper at the works, who should furnish
him with the actual expenditure under each heading of cost.

The diagram (Fig. 72) shows a form of cost statement suitable
for the several works met with in an earthwork contract.

In the case of the cuttings the statement will show the total
quantity of material removed over a period of a week or fortnight,
together with the actual expenditure for that period and the cost
per cubic yard can thereby be obtained.

Alongside of this cost there is shown the rate in the Contract
Schedule, and the Contractor can see at a glance whether the work
is being carried out at a profit or loss.

The statement also shows separately the cost of the labour,
plant, and stores per cubic yard, and from this information he
should be able to locate any excess expenditure.

Under the heading of ‘‘ Plant,” the amount in respect of wagons,
cranes, locomotive engines, steam diggers, and other heavy plant
should be computed on the basis of the cost being distributed
uniformly over a period. Two years might be taken, and on this
basis, if a locomotive should cost £2000, the cost each fortnight
exclusive of coal and other stores would amount to £38 9s. 3d.
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EARTHWORK IN RAILWAY ENGINEERING

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CONDITIONS AFFECTING THE COST 137

The statement will also show the actual cost of concrete,
masonry, and brickwork in building culverts, etc., and as in the
case of cuttings any excess expenditure should be investigated.

The importance of having these costs prepared will be more
fully appreciated when reference is made to Fig. 73, which gives

10,000C yds

 

7,000
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= o
2 ~
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a Ve a
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Hard dotted line represents cost per cubic yard.
Hard full line represents output in cubic yards, each fortnight.

Fic. 74.—Diagram of cost and output of railway cutting.

particulars obtained from the cost statements of output and rela-
tive cost of a cutting including disposal in an embankment, extend-
ing continuously over a period of twelve months. The material
in the cutting consisted of sand, or sand and gravel, and was
deposited in embankment at an average distance of about a mile
from the cutting.

Fig. 74 gives the same information diagramatically, and clearly
138 EARTHWORK IN RAILWAY ENGINEERING

shows how, with a large output, the cost per cubic yard is very
much less than what it is when the output is low.

The two best months’ work was in March and April, the average
output during that period being 615 cubic yards per day at an
average cost of 7-3d. per cubic yard. The average output over
the whole year was 350 cubic yards per day at an average cost
of 10-2d. per cubic yard. These costs include depositing in
embankment. The work referred to was executed previous to the
outbreak of the European War in 1914, when navvies’ wages
averaged about 5d. per hour, and consequently do not represent
the cost of the work at the present time.

A saving of 4d. per cubic yard in the cost of excavations spread
over 1,000,000 cubic yards represents over £2000, and this will
repay the Contractor the additional expenditure incurred in having
the costs made. In work of this description constant vigilance is
necessary to ensure the most rigid economy.

The Engineer, for his own information and for that of the pro-
moters, should be fully informed as to the progress and cost of the
works as the operations proceed, and this can best be seen in a
diagram.

Information of this description shown on a diagram indicates
at a glance whether the operations are being satisfactorily executed,
both as regards cost and progress.

As regards the cost of labour, the fluctuations of the labour
market may largely affect the cost of the work, a small increase or
decrease of the rate of wages being sufficient to very materially
influence the total value. If wages are low when the work is
being tendered for, the Contractor, keeping in view a probable
rise during execution of the works, may found his estimate on the
basis of a higher rate, but by so doing he may reduce his chance
of obtaining the contract. This difference will, of course, be more
apparent in work on which the greater part is executed by hand
labour rather than on that where steam diggers or other heavy
plant are used and where the quantity of material handled is
considerably greater per man employed during a given time.

In connection with the character of the materials to be excavated,
while the classification of “soft” and “ rock’? may be sufficient
on which to prepare a Contract Tender, these two designations very
inadequately describe the various kinds of material that may be
CONDITIONS AFFECTING THE COST 139

met with, and in many cases misrepresent the characteristics of
them so far as their removal from a cutting or placing in an embank-
ment is concerned. A dry sand cutting is the simplest and least
expensive to excavate, but, if there should be water in the sand,
the removal of it may be equally as costly and much more
troublesome to deal with than solid rock.

A tough boulder clay is the most difficult of “ soft” materials to
excavate, but certain clays or clay with sand are very troublesome
if water is present in sufficient quantity to convert it into “ slurry.”’

The cost of the work is thus largely dependent on the quantity
of water met with and the effect of water on the materials to be
excavated.

If clean, sharp sand, gravel, or solid rock is met with in the
cuttings, it will have a commercial value in so far that sand and
gravel can be used for concrete, freestone, or granite for building
purposes, and freestone or whinstone for road making and pitching
slopes of streams and water-courses.

In the case of excavations in solid rock, if it is such that it can be
put to any of the uses referred to it will generally be advantageous.
The time under which the work is to be executed may, however,
necessitate its removal by the usual methods of blasting instead
of by quarrying as would otherwise be done. A good rock cutting
is a decided asset, and the cost of excavation should be credited
with its value, provided it can be used. If there should be a large
quantity of rock to excavate, the removal of it may be the key
to the completion of the work, and it may consequently be
necessary to expedite operations by carrying them on at several
points by sinking trenches and driving headings at considerably
greater outlay than would be incurred if the work can be pro-
ceeded with from open ends.

It may be a convenience to lay an overland service route clear of
the cutting to link up the lines of communication between the works
on one side with the works on the other side, and thereby give
greater freedom in excavating the rock cutting.

In both soft and rock cutting, where it is not possible to have
free drainage from the working face, the unit price will be increased
by the expense of the pumping necessary to keep the excavations
free from water.

Considerable importance attaches to the facilities for removal
140. EARTHWORK IN RAILWAY ENGINEERING

of the excavations from a cutting. It is in this connection that the
work of a canal, dock, or other open excavation is so materially
different from the confined space generally anticipated in a stretch
of railway, road, or similar work.

As has already been pointed out, it is necessary, in order to obtain
sufficient width to excavate a cutting for a single line of railway by
means of a steam digger, to carry on the operations at a level of
about 4 ft. above the level of formation. The bottom portion
has thus to be taken out by hand at a greater unit cost. In a
double line of railway work can be carried on at formation level
with better facilities for bringing forward and removing the muck
wagons, and, if there is greater width, as in the case of a canal,
the accommodation for wagons will be still better, with consequent
less delay or stoppage of the operations. When, as is sometimes done
in canal excavations, the material is deposited on land immediately
adjoining the cutting, any delay will be due to a break-down of the
digger or excavator, and any cessation of operations will be reduced
to a minimum, and the unit cost will also be a minimum.

As already stated, the cost of the work is largely dependent on
the relative positions of the cuttings and embankments and the
length of the “lead” from the cutting to the embankment or
other place of deposit.

It is, of course, a convenience if the material can be run down
grade to embankment.

In the event of it being necessary to run material to spoil embank-
ment the cost will be increased by the rental of the land on which the
spoil embankment is situated and also the restoration of the surface.

The conditions of the weather and the season of the year during
which the work is being carried out sometimes very seriously affect
the cost. It has already been suggested that practical operations
should be commenced during the early springtime, so that full
advantage may be had of the more favourable weather and long
day of the summer season. In work extending over a period of
years every effort should be made to get as much done as possible
in good weather, and during unfavourable weather conditions
operations should if possible be curtailed or temporarily suspended.

When work is carried on in wet weather not only is the cost of
the excavations increased, but the material when put into embank-
ment, being in a sodden condition, may cause serious slipping at
CONDITIONS AFFECTING THE COST 141

a subsequent date, necessitating considerable expense in repairs.
While the men usually employed are only paid during the time
they are actually engaged, there are “oncost” charges for
managers, engineers, foremen, etc., as well as the interest and
depreciation in value of the plant in use, to be met whether the
work is being carried on or not, but it is better to stop operations
for a time if the circumstances will permit.

Under certain conditions the actual cost per cubic yard of
a cutting taken out by a steam digger may not be less than that
excavated by hand, but the larger output and the ensuring of the
work being executed in favourable weather may justify the use
of the digger.

The effect of weather conditions on the cost of the work and the
advantage to be gained by making the most of the good weather
both as regards the reduced cost and the larger output has already
been referred to.

Considerable expense is sometimes incurred in maintaining
service lines of railway when crossing soft ground, by having to
make up subsidences with ashes or otherwise.

The time ‘within which the work is to be executed may require
that operations be unduly pushed, but before tendering a Con-
tractor should satisfy himself that the time allowed under his
Contract is sufficient to enable him to execute the work in a manner
corresponding with the amount which he has stated in his Tender.
The time allowance may be altogether inadequate—no matter
what the mode of procedure may be, and not infrequently Engineers
make the mistake of not giving this point sufficient consideration.
As a common example, the greater part of the excavation of a rail-
way may be confined to one cutting, and the more economical
method might be to take it out by means of one or two steam
diggers, working from the lower end of the cutting; but, in order to
complete the work within the Contract Time, it may be necessary
to proceed with the excavations from both ends simultaneously,
and the probability is that at some points it may be necessary to
excavate against the gradient, necessitating pumping and addi-
tional steam power at greater cost. If the same quantity of
material were distributed over two or three cuttings where each
could be working independently of the other, the cost would be
much less and the work executed in a shorter time.
CHAPTER IX
SPECIFICATION

THE execution of all engineering works of importance is carried out
under Contract. The Contract Specification consists of “‘ General
Clauses’ for the protection of the rights of both parties to the
Contract. These are, for the most part, of a legal character, and
there are in addition “‘ Works Clauses,” which are descriptive of
the class of work and the manner in which the Engineer wishes
it carried out.

The Specification is framed by the Engineer and forms one of
the Contract documents signed by the Contractor, and is binding
on him for the due fulfilment of the Contract.

In the preparation of the Specification the Engineer should be
careful to ensure that what he wants is clearly brought out, and
that he is neither asking for more than he expects to get, nor less
than is essential for what he will afterwards insist on having. The
language should be perfectly clear and of the simplest description,
having only one interpretation, so that there may be no subsequent
ambiguity as to the meaning attached thereto. The Engineer
must himself understand his Specification as otherwise he cannot
complain if the Contractor fails to understand it.

In no constructional work is a Specification more necessary than
in a Contract involving the execution of earthwork, and there is
probably no other class of work where the Specification is more
frequently departed from. There has probably been more con-
troversy over questions of earthwork than any other operations
which fall to be dealt with by an Engineer.

The essential points for the ‘‘ Works Clauses ”’ of an earthwork
Specification have already been revealed in describing the various
constructive operations, and in the present chapter it is proposed
only to refer briefly to a few of the points of difference which
frequently arise in carrying out Contract work.

142
SPECIFICATION 143

Prices are cut so keen in making up a Schedule that it is not to
be wondered at that a Contractor should claim to be paid for the
slightest departure from the terms of the Contract, and at times
play on the sympathies of the Engineer to get something more
than a rigid interpretation of the Specification allowed.

A frequent cause of difference has reference to the classification
of excavations. This matter has already been referred to under the
heading, ‘“‘ Investigations as to Strata,” at page 17, and “ Cost of
Earthwork,” at page 139.

Tt is usual to have earthwork material classified in a Contract
Schedule with the two descriptions, “soft” and “rock.” A common
form of Specification reads, “ All material other than solid rock
will be paid for as ordinary ‘ excavation,’”’ and, “ Nothing will be
paid for as rock except solid sandstone, solid limestone, or solid
whinstone.” It might at first sight seem better to have a middle
classification of ‘‘ soft rock” in cases where large quantities of
material have to be removed, this term to include such material
as fireclay or other shaley clay, hard boulder clay or close-bound
gravel, which are only capable of removal by means of a pick and
which not infrequently requires to be loosened by blasting. Materials
of this description are more difficult to remove than sand, loose
gravel, clay, or earthy material, and it is the classification of
materials of this description that raises the point of difference.

Some Engineers ask Contractors to give an overhead rate to
cover all classes of material which he may meet with, and, while
this may get over the difficulty of classification, it is better that the
Engineer in calculating his quantities should have a distinction
between “soft”? and ‘‘ rock,” and the writer is of opinion that
no advantage is gained by having an intermediate class.

Part of the soft material may be very difficult to excavate, or it
may contain a large volume of water, which makes it much
more costly to remove than if the cutting was dry ; but the Con-
tractor should carefully consider these matters with the informa-
tion obtained as to strata supplemented by minute investigations
on the ground and any additional particulars he may obtain as to
the probable quantity of water likely to be met with when carrying
out the work. He must also consider what means will require
to be taken to intercept the water and direct it clear of the opera-
tions, and price his Contract Schedule accordingly.
144. EARTHWORK IN RAILWAY ENGINEERING

This raises the question of the accuracy of the preliminary
investigations which has already been fully dealt with in Chap-
ter IT. The quantities of material separated into “ soft” and
“rock,” stated in the Contract Schedule, are prepared from this
preliminary information, and if those quantities have been imper-
fectly estimated, or if any of the material to be excavated has been
wrongly described, the cost of the work may be largely exceeded
and the Contract time for completion may be inadequate.

As already stated, it is customary for the Engineer to have
trial bores put down on the line of the railway or site of the works,
and the Contractor will have the benefit of the information so
obtained. The journal of these bores should not, however, form
part of the Contract Documents, and the Contractor will require
to take the risk of the materials in the excavations turning out
different from what he may have expected. This matter is also
referred to in Chapter IV, page 47.

In connection with bridges, culverts, etc., it is important that
these be detailed as fully as possible in the Contract Schedule. All
culverts require to be constructed previous to the railway embank-
ment under which they are carried being formed and the greater
number of bridges, both over and under the railway, will also require
to be constructed before the railway is formed up to them. Conse-
quently, the materials for these works may require to be taken
over fields and inferior roads at greater cost than would be the
case if the points on the line where these special works are being
constructed were more easily accessible. The Contractor may have
a “flat” rate for masonry, concrete, etc., no matter where the
works are to be situated on the contract, but it is better that he
should have the opportunity of pricing the items for each work
separately, and he cannot afterwards have any grounds for claim
on account of the inaccessibility.

Any departure from the original schedule will, in all probability,
add to the cost of the work, and that in a greater proportion than
the increased quantities represent.

Questions relating to damage by water not having been properly
intercepted alongside of cuttings and embankments, and to the
operations not having been executed in such a manner as to pre-
vent the occurrence of slips, frequently arise. It is usual to ask
a Contractor to state a sum for dealing with slips, which sum is
SPECIFICATION 145

over and above payment for the construction of such intercepting
catch-water and slope drains as the Engineer considers are essential
for the construction of the works. The sum stated by the Con-
tractor in his Schedule may be altogether inadequate to cover the
cost of slips that will occur under the best of management, but
the Contractor is liable in any expense thereby incurred. In
carrying on his operations the Contractor will require to execute
such temporary drainage and other contingent works as are neces-
sary in his own interests, but if the operations are under proper
superintendence, the risk of damage by reason of water will be very
largely reduced.

The necessity for executing the drainage work of the adjoining
lands previous to the cuttings and embankments being commenced,
and the importance of timeously dealing with water which appears
in a cutting, have already been referred to in Chapter V1.

It is usual to stipulate in the Specification a date before which
the works are to be completed, and, in fixing the Contract Time,
the Engineer should put himself in the position of the Contractor
and consider how the work is to be done within the time which he
proposes to stipulate. The value of the work is not necessarily
the measure of the time for completion, neither is the total
volume of material to be excavated. There may be 250,000
eubic yards of excavation to remove, and if this quantity is in
several cuttings and can be proceeded with simultaneously at
various points the work will be more speedily executed than if
the whole of the material is to be removed from one working face.
The removal of the excavations from a cutting may depend on the
construction of a tunnel, viaduct, bridge, or other work, and this
should be kept in view in fixing the Contract time. As has already
been stated, the time of the year in which the work is executed
will also largely affect the time taken to execute.

Endeavour should be made, as far as possible, to avoid time
account work, and any extra work should, wherever possible,
be paid for at Schedule rates, or at rates proportionate to the
Schedule rates for similar work. There is always a temptation on
the part of the Contractor to unduly extend work when he knows
that he will be paid for it by “ time and lime.”

The importance of employing experienced men who are skilled
in this particular class of work has already been referred to, and,

E.R.E.—L
146 HKARTHWORK IN RAILWAY ENGINEERING

im many cases, a Contractor loses by not having the best of men to
supervise his operations, and this is very frequently the cause of
difference between the Engineer and the Contractor. If he should
not have the works properly managed, the most successful methods
will not be adopted, or by adopting particular methods he may
be compelled to execute certain parts of the work in winter or
during adverse weather conditions, and consequently the works
are uneconomically carried out and at excessive cost.

The Contractor requires to have sufficient capital or have the
necessary financial support to ensure that the works will not
suffer for want of the most suitable plant. It is usual to specify
that “the Company (or Corporation) do not bind themselves to
accept the lowest or any Tender.” In advising his clients the
Engineer should be satisfied that the Contractor whose Tender he
recommends should be accepted is not only financially sound but
that he is thoroughly capable of handling the Contract. For an
earthwork contract, probably more than in any other engineering
undertaking, the successful Contractor should be a specialist in
this class of work. He may have sufficient capital or financial sup-
port, but if he is not accustomed to the work he is not a success and
the result reacts both on the Contractor and on the promoters for
whom the work is being executed. If, on the other hand, he knows
his work but lacks the capital, he is hampered through not being
able to employ the most suitable plant.

The contract will probably include steelwork for bridges, and
the Engineer will require to be satisfied that it can be properly
executed and timeously supplied. If the steelwork is not erected
at the time when it is wanted, the Contractor may be put to the
expense of providing temporary trestle bridges or constructing
other temporary works at considerable expense.

Before recommending a particular Tender, the Engineer should
be satisfied that the Contractor can execute the work for the
amount of his Tender. If it is quite apparent that the Contractor
is going to lose by the contract, it is better that the promoters
should not give him the work to execute, as the work will most
probably cost the promoters more in the end than they would other-
wise have paid if the Schedule had been correctly priced.

The Contract will include for maintaining the whole works for a
period after completion, generally twelve months, and the Contract
SPECIFICATION 147

Schedule should have an item for maintenance for that period. The
Contractor may not enter a price opposite this item, or the sum
which he states may be inadequate, in which case it is assumed
that the other items in his Schedule either in whole or in part allow
for the cost of maintenance. In the case of the greater number of
engineering works, the cost of maintenance may be small, but
in the case of the earthwork of a railway the cost of proper main-
tenance may be a fairly large sum. This maintenance includes the
repairing of slips and soiling of slopes which may have been damaged
by weather, the cleaning of ditches, and the bringing to proper
level any embankments which may have subsided, and the leaving
of the work in an entirely finished condition. The cost of main-
tenance is largely influenced by the manner in which the several
works have been executed. This matter has already been referred
to in Ohapter VII.

The points above referred to are sufficient to indicate the diffi-
culties attached to the Engineer’s duties where he wishes to be
absolutely fair to the Contractor, while at the same time jealously
guarding the interests of his clients who have to pay for the work.
INDEX

A

ANGLE of repose of various materials,
100
Arch culverts under railway, 23

B

Buiastine for steam digger in hard
cutting, 53, 117
rock in cuttings, 93
Bog or moss land, 67-69
Bonuses to navvy “ gangers,” 135
Bores, additional, taken by contractors,
47, 144
Boring, chisel, 11-14
diamond, 14-16
importance of, 10
necessity for, 17
rate of progress, 17
wash-out ‘“‘ drills,” 17
Boundary fences, determined from
cross sections, 40
determined by levelling at site, 41
Box drains of timber, 22
British permanent way, 128
Built stone drains, 23

Cc

CALCULATION of areas of cross section,
42

Capital required by contractor, 146

Character of materials and cost, 6, 138,
139

Characteristics of various materials,
99, 100

Chisel boring, 11-14

Classification of materials, 138, 139, 143

Clay slopes, action of rain storms on,
107

Consideration of railway project, 2
Contract, cross sections, 40
drawings, 37
general plan, 37
longitudinal section, 39
schedule, 36, 144
specification, 36
time of completion, 145

 

Contract, commencement of, 43, 140
Contractor’s risks, 47
Conveyance of excavations, 93-98
Coolie or black labour, 72, 73
Cost of earthwork, facilities for work-
ing, 139, 140
character of materials, 6, 138, 139
price of labour, 138
relative position of cuttings and
embankments, 45
time allowed for execution, 141,145
weather conditions, 141
Cost of plant, 135
Cost of single and double line of rail-
way, 2-4
Cost statement form, 135
Cost system, 135
Cost of work over extended period, 136
diagram of, 137
Culverts, built stone drains, 23
capacity, 19, 20
constructed in advance of embank-
ments, 50
design of, 21-23
design of ends, 27, 28
fire-clay pipe drains, 22
formula for discharge from catch-
ment areas, 19
maintenance, 133
on side-lying ground, 24-26
on soft ground, 26
riveted, malleable iron or steel
tubes, 24
steel beams and concrete covering,
24,
timber box drains, 22
Cuttings, objection to cutting away toe
of slope, 54
objection to long gullets, 54
procedure in construction, 51
removal of cuttings by hand, 52

removal of cuttings by steam
digger, 53
D
DEPRESSION in embankment for flood
water, 21

’

149
150

Deviation, local, with a view to less
costly culverts or water-courses,

18
Diamond boring, 14-16
Discharge from catchment areas,

formula, 19
Drainage, interception of, necessity for,
145
Bog or moss land, 67-69
British permanent way, 128
executed before other works, 18, 49
Pennsylvania Railroad permanent
way, 132
permanent way, 129
site of embankments, 121
slope drains in cuttings, 105, 106
thorough, a means to prevent
slips, 111
works per.odically inspected, 127
Drains, slope drains in cuttings, 105, 106
large slope drains in cuttings, 108
Dwarf walls in soft cuttings, 108, 109

E

EaRTHWORE constructed by coolie of
black labour, 72, 73
exceptionally heavy, 75, 76
maintenance, 127
risks of delay in execution, 58
Economics in construction, 4
Bfficiency of control of operations, 134
Embankments, construction of high,
118
Embankments, less liable to snow
blocks than cuttings, 6
procedure in forming embank-
ments, 56, 59
in soft ground, 121
in unstable side-lying ground, 121
Engineer’s report, 1
Estimates, preliminary, 2, 8
Excavated material, disposal of, 54

F

Faocmitizs for removal and cost of
earthwork, 139, 140

Fire-clay pipe drains, 22

Flood water, openings through embank-
ments, 20

Depressions in railway embank-

ment, 21

Formula for discharge from catchment
areas, 19

G
GRAVEL, close bound, 10
Gullets, objection to long gullets, 54

 

INDEX

H
HaAND-HAMMER machine rock drill, 91,
92
Hydraulic method of forming embank-
ments, 74
I
IncERSOLL-RanpD machine rock drill,
89-91
L
Lazovr, price of labour and cost of
work, 138

Land, extent of land required, 7
setting out, 44
“Lead” down gradient when possible,
140
Location of railway, 2
Loose rock cuttings, slips, 109, 110
Lubecker land dredger, 87

M

Marntenancr, advantage of greater
width in cuttings, 4
culverts, 133
earthwork, 127
permanent way, 127-129
slopes, 132
work, contract, 146, 147

0
Open channels or pipes along forma-
tion, 131
P

Pzrwnnsytvania Railroad, drainage, 132
Permanent Way, maintenance, 127-
129
drainage, 129
section of British, 128
section of Pennsylvania Railroad,
132
Pipe drains along foot of slopes of
cuttings, 130, 131
Plan, contract, 37
Plant, necessity for sufficient plant, 146
hand labour, 77, 78
Lubecker land dredger, 87
rock drilling by hand-tools, 89
hand-hammer machine drill, 91, 92
Ingersoll-Rand machine drill,
89-91
Ruston steam crane navvy, 79-83
Ruston steam shovel, 85, 86
Wilson steam crane navvy, 84, 85.

_ “ Plug and feather,” 78
INDEX

Preliminary estimate, 2, 8
. investigations, 144
section, 7
Procedure in constructing cuttings, 51,
55, 56
embankments, 56, 59
excavating rock cutting, 62

Q

QuantirTizs, importance of accuracy, 10

R

Rattway, cost of single and double
line, 2, 3, 4
cuttings, examples, 63-67
local deviation and economy in
culverts, 18
maintenance, 4
service, 48, 139
setting out, 44
widening, 70-72
Rock cuttings, face wall in soft cuttings,
1

excavation, 62
retaining wall in soft cuttings,
lll
signal to indicate fall of rock,
133
use of materials, 139
Rock drilling by hand, 89
by hand-hammer machine, 91, 92
by Ingersoll-Rand machine, 89-91
Rock excavation, blasting, 93
“plug and feather’ method, 78
Ruston steam crane navvy, 79-83
shovel, 85, 86

Ss

SCHEDULE, contract, 36
Scheme of operations, 47
Scraper machines, drag and wheel, 73,
96-98
Section, contract, 39
preliminary, 7
working longitudinal, 46
Service railway, 48, 139
Setting out railway, 44
Setting out land and works, 44
Side channels or pipe drains along foot
of slopes of cuttings, 130
Side-lying ground, railway formed on, 5
cutting trenches on, 119
embankments on unstable, 121
slips in embankments on, 122
water-logged, 123, 124
Sleeper fence for snow drifts, 133

 

151

Slips in cuttings, 101
in cuttings requiring special treat-
ment, 113-115
in ae of large dimensions, 112,
13

in cuttings in loose rock, 109, 110
in cuttings of small dimensions,
111, 112
in embankments, 116
in embankments due to water-
logged material, 125
in embankments due to character
of materials, 124, 125
in embankments, due to character
of strata under site, 120
in embankments on side-lying
‘ ground, 122
through drainage, 111
Slope drains in cuttings, 105, 106
large, 108 '
Slope of various materials, 9
Slopes of cuttings and embankments,
50, 118
Snow drifts, 133
sheds, 133
Soft material containing water, 143
Soiling and sowing slopes, 107, 108, 119,
132
Soil-stripping surface, 51, 119
Specification, cause of differences,
classification of excavations, 143
contract, 36
contract should be explicit, 142
Spoil bank, site of, 5
Springs under site of embankments, 122
Steam crane navvy, Ruston, 79-83
Wilson, 84, 85
Steam digger, large output, 141
width of cutting required, 54
Steam shovel, Ruston, 85, 86
Stone drains under railway, 22
Strata, character affects cost, 6
character affects extent of land
required, 7
investigation as to, 9
necessity for fullest information,
9, 10
Subsidence in embankments, allowance
for, 61
Syphon pipe under railway, 33

T

TrmBer box drains, 22
Time account work, 145
Time of completion, 141
Tip wagons, iron, 94
wood, 95, 96
152

ne in side-lying ground,

Trestles, timber, 74

carrying water-course, 33, 34
Trial pits, 9, 16
Turfing foot of slopes of cuttings, 119,

WwW

Wacons, iron and wood, 94-96
side-tip versus end-tip, 60

Walls, drystone dwarf, 108, 109
face, 110
retaining, 111

Wash-out ‘‘ drill,” 17

Water, damage by, in cuttings, 102, 103
action on clay slopes, 107
damage through improper inter-

ception, 144

interception of, in strata, 104

 

INDEX

Water, large volumes of, in cutting, 115,
116

openings through embankments, 20
under site of embankments, 123,
124
Water-courses, combined in one culvert,
29
and road accommodated on one
bridge, 33
carried by a syphon, 33
carried down slope of cutting, 34
carried in open conduit, 33
carried on a road bridge, 33
carried on trestles, 33, 34
diversion along contour, 30
road and stream through same
opening, 33
Weather and cost of earthwork, 141
Widening of existing railways, 70-72
Wilson steam crane navvy, 84, 85

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