1) The gauge of a railway track is defined as the clear minimum perpendicular distance between the inner faces of the two rails. Gauges are measured at different heights below the rail table depending on the country. 2) Factors affecting the choice of gauge include traffic conditions, development of poor areas, cost of track construction, and the nature of the country. Uniformity in gauges is generally agreed to be beneficial but different countries initially adopted various gauges. 3) Non-uniformity of gauges within a country can cause inconvenience to passengers and difficulties in transporting goods between lines of different gauges. It also results in inefficient use of rolling stock and hinders future conversion of track gauges.

1. 6=$ttnginecring
Dep.rrhndnl ol C l
Dclinition of gauge of track:
wq_Ga
ilhw*un Nahar 5i A-/.-ffre-
i I) t}.AIi, GAUGES
The gauge of a raihvay tlack rs defined as the clear minit.ttut.t.t perpendicular distance
bet,r,ccn lnner laccs of Lhe ts.o rails as sho*,n in fig.4-1. Itr ittauy countries, the gauge is
r,easured bet,ecn the inncr laces of tlie trvo rails a1 a certaiu vertical distance fron-r top of
rail or rail table. ln Eurol)e, thc gauge is tlleasurecl at 14 tnt.l.t bclorv the rail table; in
Arncrica, it is rtrcasurerl at 15,88 mrll beiow thc rail table and in Japan, it is measured at 16
nrnr belou, thc rail tablc.
Roils
Fro. 4'1!-- -
G:r u gcs in diflcrcnl cottntrics:
It is secl previously thar the fir'sr public railrvay rvas laid in Britain and it is still a matter of
tlispLrtc horv the standard gaugc c.rnle iuto existence. It is believed that George Stephenson
nrcasured tl.re distance betwecn the rvheels of l.ris fam.r cafi hauled by horse tractior.r and
lound this distatrce quite convenient for his early locomotives. Later on, different countries
adopted variotrs gauges. Factors aflecting the choice of a gauge are as follows:
( 1) Trolfic Con itions:
Il tiie intensity of traffic on thc track is Iikely to be more, a gauge wider than the standard
gauge is suitabls. As rviclcr gauge can have larger sized wagous/coaches and has tnore
potcntial for higher specd arld thercby can carry more volurne oftraffic'
(2) Developmenl of Poor arets:
Narroru gairges nr" tuia i, certain parts olthe world to develop a poor area and thus link the
poor arca u'ith tltc outsidc clcvclol:cd world.
(3) Casr of trucli:
'lhe cost ofraiNvay rrack is dircctly proportional to the widtli of its gauge. Hence, ilthe fund
available is not sufficient to construct a standard gauge, a metre gauge or a nalrow gauge is
prelerred rather than to have no raihvays at all.

2. (4) 'urure of country: hc,,, r lrxrrow qlrugc o[ tl']e tlrrcli sinc. it,is ilrt''lc
I. rrrorrutaitlorts coLllltl'y' rt ts lJvisnble Io ltlvc"r
'"tll)' ?r,i' is t]rc ttr.itr rcrtsott * ltv sJrttc
ii.'i;i.'ili;;,, u'''"..il: llil"'lHIi:i-:i:ll]i,,'J'."^ll,,i;;;,t,.. g..us.. as r):.1ow 35 ortr
inlporr.;ult rails tys' t:t t''l'l j;,,ii;i;,., ,t.o influ.n... r'c choicc of guugcs
rlnt. Morcovcr. [outldat ttltl cc
The <tifferent gauges cirn broadly be dividctl into four categorles:
(l) Broad gauge: Width l676 mm to 1524 rnm or 5'-6" to 5'-0"'
(2) Staudard gauge: Witlth I435 nrm and 1451 rnm or 4'-8 5" and 4'-91/8"'
(3) Merre gauge: Width
.l067
nrm' 1000 mm and 915 mm or 3'-6"' 3'-33/E" and 3'-0"'
(-l) Narrorv gaLrge: Width 762 r.nm and 610 mm or 2'-6" and 2'-0"'
TABLE 4.I
RAILWAY GAUGES IN VARIOUS COTNTRIES
Name of couutrtes
Bangladesh, India, Pakistan' Ceylon'
Brazil, Argentine
Spain, Portugal
lreland, South Australia
Russia, Finland
(1)Broutl guuge:
(a) 1676 mm
(b) I670 nint
(c) 1600 mnt
(d) 1524 mtrt
England, U.S A , Canada' TurkeY'
Persia, China. EgYPt' Australia
Europe (excePt Russia' SPain and
PortLrgal)
(2) Standartl guuge:
(a) 143 5 ntnr
(b) 145 I mnt
South Africa, Japan, Java' Australia'
New Zealand
Bangladesh, India, Fr ance' Switzerland'
Argeniine
(3) lvletre guuge:
(a) i 067 ntm
c) 91 5 tnm
India, Britain
lndia, South Afr-ica
(4) Nurrort' guugc:
(a) 762 mrr
(b) 610 mnt

3. Unifornrity in gauges:
It has bccn gcucrally agreed that a country should have a uuiforut gauge.'l'his I'act has Icd
to scrious thinking in thc coLuttrics lraving nrorc th:rn ot]c gaugc and attclllllts arc bcitlg nratlc to
pass an tct of Got,cntnrent in this connection. Various causes which have arisen due to non-
unilonrity ofgauges are as lollows:
( 1 ) Itrcottvutiencc to passcttgers
At the point rvhere therc is a change ofgauge, passengers are required to move from one
train to the other. This transler involves difficulties such as getting accommodation in the
nqv train, translerring luggage frorr one train to otlier, climbing staircases of overbridges,
ctc. Morcovcr'. tftc tirlilgs of thc t',vo trains arc to be correspoudingly adjusted. Sometit]lcs,
this ntay rcsult in ntissirrg the train and thell passengers lrave to pass the time orr tl.re
plarforms. Moreover, i:rsanitary condilions will be developed on the platfomrs due to their
conslant usc.
(2) Difficulties for se n irrg gootls
(a) The labour required lor loading and unloading the goods may go on strike and thus
completely dislocate the ntovement olessential goods required for various trades. The
problenr gets lurthcr complicated lor goods sent loose or in bulk such as coal, lime,
Iimcstonc, stonc chii)s, ctc. bccausc it is obscrvcd that at cvery transhipnlcnt point.
there arc certain groups of labourers rvhich are specialised in the handling of suclt
matcrials. Flence it becorres difficult to cmploy other labourers in an emergency, even
though there may be cousiderable unemployment in the area.
(b) lt is most likely that delicate goods may be damaged during the process of loading and
unloading.
(c) Thcfts or misplacenrent ofgoods nlay occur during the transhipping which may lead to
inconvenicnce to the pclsons concerned and long unnecessary corespondences are
thus unduly created.
(d) Large costly yards are to be provided at the junction o[ tl.re two gauges to store the
goods.
(c) Onc or nrorc cxlra chargcs rvill have to be paid by thc owncr of the goods rvhich will
result in the increase in cost of the product.
(3) Inefficient use of rolling stock:
It is quite clear that a wagon of metre gauge cannot be used on a broad gauge. Thus.
sometimes, this results in artificial shortage of wagons. Many wagons may be lying idle on
broad gauge line while there may be an acute shortage ofwagons on the metre gauge line.
Had there been a unifon.n gauge, sucl.t difficulty would never have arisen.
(4) War time dilficulty :
lfthe gauge is not unilolur tlrroughout the country,
by rail lronr one corncr of the country to the other
amount of time.
it becomes difficult to trarlsfer the arn.ty
comer of the country in a very limited
5) !)quipnrent at statiou:
A station where two gauges rneet, will have to be provided with duplicate facilities such as
platforms, sanitary arangements, sidings, clocks, ticket offices, etc. This will result in extra
J

4. Uniformity in gauges:
It has bccn gcncrally agrccd that a country should have a unilbrnr gaugc. 'l'his liLct l.ras led
to scrious thinking irt tlrc countrics having nrolc tlran onc gaugc and tttctttPts arc bcitlg I.tladc [o
pass an act ofGovcntnrent in this connection. Various causes rvhich have arisen due to non-
unilornrity ofgauges are as lbllo*'s:
(l) Incontenicucc lo posscttgcrs
At the point rvfiere therc is a change of gauge, passengers are required to n]ove from one
train to the other. This transfcr involves difficulties such as getting accomn.rodalion in the
nes, train, transferring luggagc lrom one train to other, climbing staircases of overbridges,
ctc. Morcovcr. tlrc tintings of thc trvo lrains arc to bc corrcspondingly adjusted. Sonletittles,
thrs uray rcsult ir.r ntissing the train and thcn passengers llave to pass tlie tirle on the
platlonns. Morcover, insanitary condiliorls will be developed on the platlomrs due to their
col)stanI usc.
(2) Dilficultics for serrdittg goois
(a) The labour required lor loading and unloading the goods may go on strike and thus
completely dislocate the nlovenlent of essential goods required lor various trades. The
problem gets lurthcr conrplicated lor goods sent loose or in bulk such as coal, lime,
Iimcstope, stonc chips, ctc. bccausc it is obscrvcd 1ha1 at cvery transhiltrucnt poiltl.
there arc ccrtain groups ol labourers rvhich are specialised in the handling of such
matcrials. Flence it becoures difficult to enrploy other labourers in an emergency, even
though therc rnay L.:e cot.tsiderable unentployment in the area.
(b) It is most likely that delicate goods may be damaged during the process of loading and
unloading.
(c) Thefts or misplacenrent of goods may occur during the transhipping which may lead to
inconvenicnce to tlle pcrsons concemed and long unnecessary correspondences are
thus undu ly c reated.
(d) Large coslly yards are to be provided at the junction of the two gauges to store the
goods.
(c) Onc ol ntorc cxtra clrargcs will have to be paid by thc ownet'of the goods rvhicir rvill
result in the increase in cost of the product.
(3) Incfficient use of rolling stock:
It is quite clear that a wagon of metre gauge cannot be used on a broad gauge. Thus:
sometimes, this results in artificial shortage oiwagons. Many wagons may be lying idle on
broa<l gauge line while there may be an acute shortage ol wagons on the metre gauge line.
Had tl.rere been a unifon.u gauge, such difficulty would never have arisen.
(J) war time dilliculty :
If thc gauge is not Lrni fornr throughout the country, it becomes dilficult to trai]sfer the arnly
by rait from one comcr ol'the counl.ry to the otller corner of the country in a. very Iimited
aniount ol tinre.
5) llquipment at station:
A station where two gauges rneet, will have to be provided with duplicate facilities such as
platforms, sanitary arrangements, sidings, clocks, ticket ofhces, etc. This will result in extra
?t
{'

5. ,'
't: i'
cxpenditure.
61 llintlcrance ibr futurc corlYcrsiotr:
Itbccot:rcs,cfydifficultandplacticallyunecollolnlcaltolvidetranexistillgtrackir-rlirturo
.hctl lleed arises. l.his is Jrc',ro th" tact thar changc in gaugc also involves change in the
climeusions of roiling
"ott'
ona other structures such as tunl'Iels' bridges' etc'
1

6. Rails
Irunction of Rails
Rails are sintilar to steel girders. Thcse are placed end to end to provide continuous and level
surlacc for the trains to nrove. Thc finishcd or conrpleted track of a railway line is commonly
krrorvn as Peraunu I,Va.1,.
Rails pcrform the following functions:
l. The rails provide continuous and level surface for movement oftrains.
2. The rails provide a pathway which is smooth and has very less friction. The friction
be[veen steel rvhee] and stecl rail is about l/5th of the friction between the pneumatic tyre
aitd metalled road.
3. The rails scrve as a latcral guide for the running ofwheels.
'1. The rails bear the strcsses developed due to vertical-loads transmitted to it through axles
anLl rvhecls ol rolling stocli as rvcll as due to braking forces and tl'reflral stresses.
5. The rails carry out thc lunction oltransmitting the load to a iarge area of formation tluougl.r
slecpers and ballast.
Types of rails
I . Double hcarlcd rails
2. BLrll lreadcd r:r i ls
3. FIat lootcd rails
originally, the rails used were double headed (D.H.) and made of "I" section or Dumb-bell
section (Fig. 5.1.) The idea *,as that when the head was vr'om out during the service, the rail
cotrld be invertcd and reused. Tl.re expcrience, horvevcr, ihowed that the bottom table of the rail
was dcntcd to such an cxtent in scrvice by long and continuous contact with the chairs that it
was nol possible to reuse it. This led to the development of Bull headed (B.H.) rail which had
almosl a sinrilar shape but with nrore metal in the head to allow for greater wear and tear (Fig.
5.2)' This rail scction had orte big dlawback that chairs were required for fixing it to the
slcepers.
A llat lboted rail, also callcd vigttolc rail (Fig.5.3), having a cross section ofinverted r- type
lvas, tltcrcforc, dcvclopccl wltich coLrkl bc fixcd dilcctly (o thc slccpcrs witlr thc lrclp of spikcs
ctc- Allothcl' advatttogc wilh tlrc flat-looted lail was that it was a morc ccononlical tlcsign
giving grcatcr strcrtgLh arl(l latcral stability to thc track as cornpared to a B.ll. rail lor a given
cross sectional area.
Adrn,,trgn, of flat looted rails:
(i) Chairs: No chairs are required in this fonn ofrails. The foot ofthe rail is directly spiked to
the sleepers. This fact nrakes theur economical.
(ii) Stllessr This fonn of rail is stiffer, both vcrtically and laterally than the bull headed rail
ofequal weight. Especially on curves, the lateral stiffness ofrails is vely impofiant.
(iii) Rinks: This lbrnr of rail is less liable to develop kinks and it maintains a more regular top
( o-a
r

7. surllce than thc bull headcd rails.
(iv) Cosr.'The flat footcd rails are lound
l') Load distributiott: Thc flat looted
slcepcrs.This results in grcatcr track
maintenance costs, less rail lailures and
to be clicapcr than the bull headed rails.
rail distributes the train load over a great numbei of
stability, longer li[e of rails and sleepers, reduced
few intemrptions to traffic.
LO
,-U
4d^^
I64 nm
,i-
TI
IDouble hcadod rail
-=-Eo-:E:i--
Bull heoded radls (69. 5-2)..
F<- 64 .nm ---+!
Bull hcadqd rail
Fro.5-2
Flat footcd rail
(2)
T
46 z'rr.
!
I
I
I
I
+
,rg-
r.
!r
l.;,,4rlt47A8
- r3.8e mm I
I
,..6 I
------rl
66.68 mm
.--
'_?
.,/'
,
t.t
tljL_
-..-----
13A53min
10.64
T
l45mm
I
f-.
{
Web
mrn
.+
q
l* TOmm -*l
le 68-55rnn ---t
Fro.5-3

8. W,;ight of rail and its relation to uxle load
A rail is dcfincd by its rvcight, c.g,,45 kg rail means that rhe weight of rail per rnetre lcng[h is
45 kg. Scvc'rai lactors arc to be considered belore deciding the rveight olrail and its sections,
the chief aniong tltem are as follorvs:
L hcav icst axle load
2. gauge of track
3. maximum pcnlrissiblc spced
4. type and spacing ofslecpers
5. depth ol ballast cushion
6. nalure of traffic.
Though the weight of the rail and its section depends upon various considerations yet the
heaviest axle load which tl.re rail has to carry plays, the most important role. It is lound and
vcrificd by cxperinlcnts that the axle loads on locomotives directly depend on the weight of
rails used in thc track.
Tirc lbllorving is thc thu:rib ru)e lor giving the rnaximum axle load with relation to rail section :
Maxintum axle load
For rril of 90 lb pel yard, rnax. axle load
For- r-ail of 52kg per n1, ntax. axle load
Requirements for an ideal rail section'
l. The rail should have most economical section consistent with strength, stiffitess and
d urab i tity.
2. 'l'hc ccrrtrc olgravity olrail section slrould prelerably be very near to 1he centre ofheight of
rail so that nraxinrurn tcnsilc and conrprcssivc stresses are equal.
'1. A rail prirnarily consists ol a head, web and foot and there should be an economical and
balanced distribution of utetal in its various components so that each of them can fulfil its
requirernents properly.
The requiremetrts as well as the niain considerations lor design ofideal rail section components
are given below:
(u1 IIeod:
The head olthe rail should have adequatc depth to allow for vgrtical wear. The rail head
should also be sulliciently wide so that not only wider runnirlg sufrdis available to
reduce lhe contact strcsscs betwcen the rain and whecl but the rail has the dcsired ]atcral
stiffness also,
(b.t Web:
The web should be su ffi c.lg1.lI1b@k so as to wirhstand tl.re stresses d.e to the loads
corning on it aft", oli6iil! fonio.rnal conosion.
(c) Foot:
The foot should be of sufficient thickness so as to withstand vertical and horizontal
lorces after allowing for loss due to corrosion. The foot should be wide enough so as to
be stable against over tuming. The design of foot should be such that it can spread the
load on a large arca of sleeper.
= 560 x sectional weight of rail in lbs/yard or kg/m
: 560 x 90 lbs = 22.5 tons
560 x 52 kg - 29.l2MT
'+

9. Corrugated or roaring rails:
Mcaning:
In certain places, heads of the rails are found not straight but corrugated, i.e., with a rvavy
surlace. Such rails arc knorvn as corrugated or roaring rails and when vehicles pass over such
comrgatcd rails, a fg!.iggnd is created.
Causcs:
Thc plicuorlena ol corrugation of rails is very complex and hence, it is
mcntion specific causes lor the same. However, following are the possible
contribute to the commencenrent and development of corrugation of rails: '
( I ) coning of engine rvheels,
(2) excessive slack or excessive tight gauge,
(3) high speed o f trains,
(4) non-urrifonnity olthc diameter of engine wheels,
(5) presencc of high huuridity and dust in the atmosphere,
(6) rigid railrvay track,
(7) slipping of wlrr:cls oIengirtes,
(8) snrall spacing betrvcen driving axles ollhe locornotives,
(9) sudden application o f brakes,
(10) use ofstccl having high nitrogen corltent and high tensile strength, etc.
Occurrtncc:
The corrugatcd rails arc lound norrnally at tlie following places along a track:
o At tlre points olstarting and stopping of the trains.
o On elcctrificd scction ofa raihvay track.
o Where ballast used lor the railway track consists ofbroken bricks.
e At long tuinel
o At steep gradient
Effects:
o The track with corrugated rails produces discomfort to passengers due to rlryUiding
r@"".
c Whcn vcl.ricle pass ovcr thc corrugatcd rails, a roaring sound is produced.
o This unplcasant and cxccssive noise causes great inconvenience to the passangers.
cr The ruuuiug of trains on corrugatcd rails leads to overall deterioration of the raihvay
track, loosening of the fastenings, disturbance in ballast bed, loosening of anti-creep
devices, etc.
Rcnrcdy:
The only remedy which is practiced at present to remove corrugation is to grind the corrugation
of rails by special machines. A rail-grinding train is run on the affected section at a specified
speed and the pioccdure is continued till com.rgations disappear.
not possible to
factors which

10. Corrosion of rails:
Sonletimes thc rails arc corroded. The phenomena olcorosion of rails is urainly due to the
prcscnce ofdamp conditions. It is usually seen in active i.!d*!!r,.I areas, wet tunnels, near ash-
Dits. etc.
Follorving are the effects of con osion of rails:
e Rail section is gradually reduced.
o The latigue strength ofa rail is lowered.
o Therc is considerable increase in wear ofrail and ifcorrosion is not prevented, it may
lead to the lailure of rail.
To prevent corrosion, various ntcasures nray be adopted. Such measures can broadly be divided
into thc lollorving_!q categorics:
o Quality of rail: For the areas where corrosion is likely to occur, rails prepared from
special :tgelor a lloy steels are employed in the construction ofpemranent way.
o Surlace treatlnent: The rail surface is coated with non-corrosive material. For this
purposc, special paints, red lead, birumcn, cqqllsr, etc. have been tried. The surface to
bc coatcd is Lhoroughly.i"ffi tr" i5[-rtl" ,f,li-cor ion of coat.
Leugth of rails:
The tendency at present is to adopt a rail olmore length. The marn advantage ofa longer rail is
that:
o it clinrinates joints whicl.r are the weakest part of the track.
c less nurrrbcr of ruil fastcnings
c this results in lorv consl.ruction & maintcnance cost
o sntooth running oltrains and comlort to passengers.
The length ofrail is, however, restricted due to the following factors:
o Difficulties in manufactLrring very long rails.
ll/car of rails:
The rail head gets lvom out in course of time due to
o friction between the rail and moving wheels.
o ilnpact produced by acceleration, deceleration an<i-braking ofwheels.
o abrasion caused by rail-rvheel interaction.
o thc eflects of weathering like tenrperature, moisture chainge
o Lack of lacilities for transport, lifting or handling longer rails.
o Dilficulties in having
"
qg.Cgl"-I3qlgugfgr for long rails.
o At thc fittings heavy inllnBllglnel stresses in long rails.
Depending upon thc above consideration, various countries have adopted different length of
rails. Bangladcsh, India adoptcd 12,80 rn and I I .89 m as stan<.larcl rail lcngths for. B.G. 11d
M.c. rcspcctivcly. 'fhc nonral rail lcngths in America, Britain, trance arid Germany are 11.g9
m, I 8.30 m, 24 nr and 30 m rcspectively.

11. Li'!<->,
Thcsefactorscauseconsidelablervearandtearotrverticalandlateralplanesoniheraillrcad.
Eventually, u'lrich results in loss of weight ofrail'
Types of wear on rails:
Dcpcnding upon its location, thc rvcar ol'rails can bc classified as lollows:
o Wear orr top of rail hcad (vcrtical wear)
l Wcar on cnds of thc rails (battering of rail cnds)
c Wear on sitlcs of rail head (lateral wcar)
Each type rvill norv bc described in briel
(t) lcur ott loP o,' hcutl of rails:
Therrretalfromtltctopofrailtlorvsandlomrsprojections'Theseareknownasbltlgasshown
rn fig. S-S. Follorvingare lhe c4trscs lor such type of wear ofrails:
(a) Rails are wonl out on top due to abrasioll olthe roiling wheels over them
(b) The heavy rvliecl loatls are conccntrated on very small areas This results into flow of
metal from toP.
(c) Impact of heal'y loads causcs top ofrail to wear'
(c])Wheelburirscausedbyslippingofthedrivingwheeloflocomotivesontherailsur.face
resulting in a dcpression oll the rail table'
(e) The grinding action of the sgd.pSrtjqes between the rails and wheels help wear of rail
on toP.
({) Conosion olmc(al olrails, especially"tl"giEu, will cause wear of head of rails'
ig) the metat of top o l1a!![g1s during starti])g whcn the wheels slip or rvhen
'brakes
are
lpplicd to tltc tlor ittg lrritts'
(2) lVctr al tht tnls of rtils:
This rvear of rails takes place at the ends ofrails and is found to be very much greater than the
*"", u, ,op of rails. At ihe expansion gap, the wheels ofthe vehicle have to take a jump and
Juring ttrii 1ump, they impart i uto* ,J ti.,. ends of the rarts as shown in hg. 5-6. This blow is
,f*
"i^i" "uus"
of *ror of rails at ends. Due to successive blows, the ends of the rails are
battcrcd and various othcr cflccts are sccn whicl.r further increasc this type of wcar' These
effacts ate as follows:
(a) Fish-bolts and fisll-piatcs bdcorne loosc
(b) The colltact surlaces betwecn rails and sleepers are wom ou['
i.j it""p.r, at expansionjoints are depressed due to settlement ofballast at these points.

12. {
Wear of rail at ton W/
.
Fro. 5-5
(2)
)
(3) Wear on the sides of thc head of rail:
Flc.5-7
Wear on Side of Rail
Wcar of rail at cnds
Fro. 5'-6
ffiiilr,rg.,
""
This is thc rnost dcstructivc typc ol
wear and occurs rvhen tracks are laid on
curves. The carses of this type of u,ear are
as follorvs:
(a) Due to curvature, pressure due to
centrifusal force causes grinding action of
the irLner side ol the head
ofthe outer rail.
(b) The vehicles do not bend to the shape
of the curvature while uroving over l
curve. This results into the biting of the
./,
/
,/
nn,, %'/ 'N outr
Roil* A H- tottd/')v7> << ';///
Wear of rail on sides rrc. 5-8
inner side of the head of outcr rail by wheel flanges.
ln*r Wred
of rail o#des
.1' ;
v'

13. (c) The rvear on inner side olhead ofinner rail is mainly due to lhe slipping actlg]lgf w_hgei on
curves. lt is clear liom fig. 5-7 that the outer wheel has to cover a longer distance than the inner
u'heel as pg is grcater tiran rr. But due to rigid connections betwcen two wheels, thcy cover the
same distancc and hcnce, the inner whcel slips ovcr the inner rail, resulting in the wcar of inner
side oIhcrd of irrncr rail. [:ig. 5-ll sJrorvs thc rvear olrail on sidcs.
Nlcthods adoptcd to reduct rveur of rails:
In addition to coning ofrvhcels and super-elevation, various nrethods, as nrentioned below, are
uscd lor the purpose of rcducing rvear of rails:
o Use olspecial alloy steel
c Use of heavier rails
o Good nraintenancc of track
o Reduction of expansion gap
o I{eductron ol nunrbcr ofjoints by wclding
o Exchange ofinner and outer rails on curves
o lntroducing parallcl clrcck rails (usually wont oul. rails are used as check rail)
c Lubrication olgaugc lacc olouter rail in case olcurves.
-.
Coning of rvheels:
The flanges ofrvhecls al.c ncver made flat. But they are in shape of a cone with a slope ofabout
I in 20. As the ivhecls are set on the axle, there is some chance for lateral movement belween
the flanges of the wheels and the rails. Hence, without coning, the flanges rvould cause a slight
but sudden shock to the sides of the rails-
Behaviour ofconed rvlrcels on straight and level track is shown in Fig:5-15. In this case, tl.re
llaugcs ol rvhccls have eclual circumlcrence. But the situation is different when the wheels
move along a curve as shown in fig. 5-16. In this case, the outer rail has to cover a greater
flongc Coned ! in 2O
Bchaviour of concd whecls on.lcvel track
Fro.5-15
l:20
l: f o
lrrret Roll Oulcr
Bchaviour of coned wheels on
Fro.5-16
Roil
curveS

14. distance than that of thc inner rail. Also, as the vehicle has a tendency to rnove sidcways
towards tlre outcr rail, thc circLrnrfcrence of thc flange of outer wheel will be greatcr than that
of tlte inncr whcel and this will help the outer rvheel to cover a longer distance than the inner
rvht'cl.
Corrrog of s hce ls is nrlirll, dorrc
:r to rnaintain tirc vclriclc in the ccntral position with respect to tl.re track. and thereby
o to avoid f iction bc[rvecu rail and wheel rim
o to mininlize slipping of inner wheel when moving along,a curve
Coning of wheels has tlie lollowing disadvantages:
( I ) Smooth riding is produced by the coning of wheels. But the pressure of the horizontal
component near the inner edge olthe rail has a tendency to wear tlie rail quickly.
(l) l'he horizontal corlporleuL terlds to tum the rail or.rtwardly and lience, the gauge is
sonletimes r.vidcncd.
(3) If no brsc-platcs arc providcd, slccpcrs undcr the outcr edge olthe rail are damaged.
In ordcr to nrirrir:risc thc above-mentioned disadvantages, tiltittg of rails rs done, wl'rich means
that the rails are not laid fiat, but they are tilted inwards. The most common method adopted for
tilting ofrails is to use inclined base-plates as shown in fig. 5- 17. The slope olthe base-plate is
I in 20 which is also the slope ofthe coned surface ofthe wheel. Following are the'adyantages
of rilrirry ol ruils:
'^"u;:1.lTiro'"*
: The tilting of rlils ntain(ains tlie gauge properly.
c The u'ear olthc head olthe rail is unifonl due to tilting ofrails.
r The tilting of rails increases the lile ofsleepers as well as rails.
Ilogged rai Is:
Rails wliich are bcnt vcrtically at the ends are known as hoggecl rails and they are fonned
duc to wear of rails on cnds. Thc hogging rails causc dcterioratior-r ir.r the running quality of tite
track. -fhis is or.rc of the serious rail delects and the following methods are used to rectily such
danraged rails:
( l) The hogged rails should be removed and replaced by new rails. However, this will be
very uneconomical. But some economy is achieved by using hogged rails on sofle un-
irnponanl. Iines.
(2) The end portion of the rail is cut-off and fresh holes are provided for fish-plates. Thus,
the rail is shortened but can be used conveniently. This cutting can be done either at
depot or at site. The fomrer method is tedious and unecononiical as the rails are to be
taken to the dcpot, rcpaired and then brought back to the site. In the second method, a
portable drilling machine and power saws are used. The rail ends are cut-off at site only
and then the rails are pulled back corrcsponding to the length ofcut-off. This method is
Slop€ L; )O
{

15. uscd in U.S.A. aud was provcd to be quite successful
(l) Fioggctl rails can bc inrproved by rvelding the rvom ends of the rails'
(1)Hoggedrailscallalsobeinlprovedbysorrresirrrplcclcvicesuclrasadelnggedntuckinc.'
It c-o-nsists of a bottie jack, , lcngtt] of old rail and two sets of clamps. This machine is
uscd ,,vitlt sttcccss in India.
Ilucklittg;
Sonrctinres, lorrlatior.r ol buckles takcs place which nleans that the track has gone out of its
original poiition. This happens on.,,ru.i when expansion ofrails is prevented. The preve.tion
oI erpltision Ittay bc due- to ottc ol'the Ibllowing ,]vo causes:
(l) insulficietlt cx1;attsion gap. antl
(2) excessive tiglitncss of the joint.
Buckles in tracks are serious ancl sonletimes, they are responsible for the derailments of the
trains. Hcncc, propcr ci)rc shoulcl be takelt to avoid buckles. Precautions to be taken are as
follorvs:
i. Expar:sion ga1; shoulcl be sulficicnt.
2. The fish-bolts shor.rld not bc tightcned up to such an extent as to prevenl expansion or
contracl.iott ol' rli ls.
j. The corltact surlaccs bctrveen thc fish-plates and rails should be periodiially lubricated.
hL

16. i 3i SLEEPERS
I;unctions ol s le cpcr.s
Slccpcrs arc lrlllsycrsc tics ott rvhiclr llrc rails arc laid.'fhe LIain lunctions ofslccDers are ls
[o Ilori s:
-.r Llolding rails to corrcct Saugc and alignntcnt.
r Civing a finl and evcn support to rails.
: To nraintain tltc alignnrcnt and gauge of the track correctlv
'r 1'rarrsrcrring rrrc road *'crrry riorr the .ails to r.vider ur.u of ,h. bn r.,.
-: Actirrg as u, crastic nrediu, betrveen the rairs and the balrast to absorb the brorvs
arrd r ibratiors ol ntor.ing loatis.
-.r l)rovitling iongitLrdirral and latcral stability to pcnlanent wly.
r Pror,iding ntcans to rcctify the track gcornetry during its service life.
Requirements ol' an idcal sleeper
Ihc i<leal sleepcr.should nor.nrally lulfil tlie lollou,ing requirements:
c Thc initial cost as well as uraintenance cost should be nrinintunr.
:: Thc rreight o1'thc sieeper shoukr be nioderate {br ease ofhandiing.
= The design of slcepc. a,d faste.ings should be such that it is possibre to fix anil
rcntovc thc rails casily.
e fhc slccpcr shoulcl havc sufficient bcaring arca.
-"r 1-lrc slc'cpcr srrourd trc sucrr rrrat ir is possibrc to maintain a.d adjusl gatrge properly.
:r The rnar'criar o1'sJccpcr urrtr its desrgn shoLrrd be sLrch that the sreeper does noib,.erk
or get damaged rvhile packing below the sleeper.
-.r The dcsign olslccpcr shouid be such that rt is posstble
-.r 'l'he slccpcr shoLLlti be capabie olresisting vibrations
T1,pes of Sleepers
Dcpcrdi.g upon thc posirio' in a railway track, siccpers may be classilied as
''t Longitudinur srecpcrs- I'rrcse are the earry rorm ofsleepers a.d consisted orslabs ofstortes or picces of tinrbcr praced paralrer to the rairs as shown in fig.7-1. At presenr
they are not being used because high cost and poor perlbrmance.
e Transverse sreepers - Trarsverse o. cros.-sleepe.s were first introduced in the year
1835 anci rncy arc rrow univcrsally adopted. They have b.."-" ;;;;;;,_; ;;; **renrove ,' Lhc disadvanrages of the rormer type. They are placed at right-ar.rgres to the
raiis as shorvn in trg. 7-2.
fast nroving trains.
r The sleepcr should have anti_sabotage and anti_theft
to har e rrack cir.curring.
and shocks due ro passage ol
qualities.
i{
I

17. t4//
Depctrding Lrpon the rnateriul transverse/cross sleepers may is classified as
-.r 'oodcn slccpcls
-.i Stccl s lccpcrs
r Cast iron s lccpers
J Concrctc slccpcrs.
'oodcn Sleepers
Woodcn sleel;er is thc tttost idcal typc ofslecpcr and it is being used universally ahlost evel'
sittce tltc invctt(iott of Ilil*.tr,. Its utility hus not tlccrcascd witlr thc passagc of tinrc. Only thc
possiblc sltorl:rgc ol's,ooti ir fittttrc hus lcrl ltr llrc llrirrltirrg ofslccpcrs ol'othcr ntatcrials.
Ihc rvoodcn slcepcr Iras tlte It-rllorvitrg lrrirrn advantagcs arrti rlrsadvurrtrt:es .
Adyflrtl ges
o Cheap arrtl casy Lo ntanLrlacturc.
:: Absorbs shocks lnd Ius gor good ca1:acity to dantpetl the vibrations
o Thercby retarns packing rvell.
c Easy harrclling witllout diintagc.
o Suitahlc for track cilcuited sections.
: Suitablc lbr aleas har,ing yielding forntations.
u Alignnrent can bc easily corrected.
:: Morc suitable lol rnoclr: rn tncthods of nraintcnancc.
Lr Can bc uso(l u,itir or rvithout stone ballast.
e Cirn be uscd on blitlgcs and ash pits also.
Disulvuntagas
i.: l,csscr iil'c iluc to n,car, dccay and attack by vennin.
u Liablc to mcchanical wcar rvitlr bcalcr packing.
o Difficulty to nraintain gauge.
o Susceptible to llrc hazards.
tr Scrap value is negligible.
Sr.c.'The size of'sleepers will depend
Standard sizes ol- titnber slccpers used
: I;or [].C., 274 cl"r x 254 rnnt x
c For M.G., 183 cnr x 203 nrnr x
:.t Iror N.G., I 52 cnt x 178 rnrr x
upon the load coming and the quality of wood.
are as follo*,s:
127 nrnr.
I l4 rnm.
I I 4 nrnr.
,jL

18. ,,1 ::.itrg oJ lllootlctt Sltcpars
Iil order to enablc tile rails to l)c slightly tiltcd inu'ards at a cant of 1 in 20 the Wooden slcpcrs
rc rcqlrircd to bc cut to this slopc at rail scat bcfore laying. This proccss ol- cutting tlrc
soodcn slccpcl at a slopc ol' I in 20 is knorvn as 'Adzing of Woodcrt slccpcr'.
It is to bc donc ri ith grcat carc othcnvise the slopc u,ill vary lrom sleepel to sleeper resulting
in roLrgh riding.'fhc adzcd surlacc olrloodcn slccper is treated rvith coal tar or creosote to
cnsLrrc ploper protcction oi'surlitcc. Nonlally adzing olrvooden sleeper is done only when
bcaring platcs arc not provi(lcd.
S teel S lecper
-fhc
inclcasing shortage ol'tirlircr and otircr ccononrical lactors are urainly responsible ibt the
use of steel slecpers. The stcel sleepers have the lollorving main advantages/disadvantages
over the rvooden sleepers :
Fig. 7.1. Stcal Trouglt Sleeper (8.G.)
Advtnloges
u Longer life.
o Easy to maintain gauge and lesser maintenance problems
c Bertcr lateral rigidity.
o Lesser dan:agc dtrring handling and transport.
o Manulacturing proccss is simple.
:.r Vcry good scr:rp r;rltrc.
r Free llonr dccay arrd attack by vcnlin.
tr 1-ot susccptible to llrc hazards.
Disuth'ttrrtngcs
--.: l-iabie to corrosion.
-.r Urrsuitable [or track circuitrrrg areas.
-.r t-iablc lo bcconrc ccntrc bound bccausc ol'slopcs itt two cnds
-: Dcve lops cracks at rail scats during scrvice.
:.r Can only be used lor rails lor."vhich it is manufactured.
Dasigtt l"oatun:s
-l'hc
stcel trough slecpcl cssentially consists of a rolled steel plate of about 12mm (1/2")
thickness and pressed to suitable trough shapc and rhe rail seat canted to I in 20. The ends of
the rolled section are flattcned out in the shape of a spade to retain the ballast. Tno
Jf
l4{",.l.- zro .-l
SEC. AT A-A

19. lultcrnativc typcs of slccltcls htrvc bccn designcd lbr each raii section as. per dctails givcll
hclorr:
(l) ln otlc t),pc, thc lLrgs or jarvs arc ltlcsscd out ol'thc platc itscll- to irccollll)]ollatc tllc
lbot ol rlrc rail a:rd thc kcy (Fig.7.5). Thele are a lot ol maitttenance problenls with
rlrese llrc'sscd up Iugs its thcy git,c way duc to the utoventeut of thc keys as rvell as due
to the vihrations ancl itrtpact of tlre nloving 1oads.
(2) 11 ordcr to obviatc this dc{cct. auolhcr dcsign ol slcspcl's has bcctl adopted. In this
typc, to hoies ar.c punchcd in the plarc on cither sidc ol the plate to acconlnlodate
specially dcsigned 'Loosc jarvs' (Fig 7.6). Thc rails are l.reld rvith the help of trvo
stantlartl ke;'s tlrivcrr cithcr i:r thc lttcsscti Lt1> lttgs or in the loose-jarvs.
Fig.7.5.Sslcepcr with pressetl- up lugs
'l'he adjustntent of thc gauge to tltc cxteltt oli 3 tunr (1/8") is dole by proper driving of the
keys. In the dolble linc section, the keys are driven in the direction of traffic. The weight of
standard B.G. tlough slccpcr is 81 kg and that ol M G. sleeper is 35 kg approximately. The
stcel Irou,lh slecpcr has iln avcrage lif-e olaboLrt 50 years. It is an acceptable type of sleeper
lbr usc witS long rvcllcd rails bccaLrse of its latcral stability and its adaptability for use u'ith
clastic lastcn ings.
KEY Ki:Y
l;ig. 7.6 Sleqtet' x,itlt loosc.iatt,s irrscrted itr ltoles
^rJ!
."i, l,
Fig, 7-7 Steel sleeper *,ith bolts
PEESSED
LOSEJAW
$$mTEo W

20. Cast I ron S lecpers
The nrain advantages and disadvantages
lollos's:
Adt' ,ttagcs
:l Lcsscr corrosion.
-J Lcsser liablc to crack at rail scat.
-r Easi,.'r lo rnlrtttf;.rctttrc.
: H igher scrap valuc.
Disa va,iugas
ol C.l. sleepers over stecl trough sleepers are as
r Cauge nlaintcnance is difllcult as tie
-: Providcs lcsser lateral stability.
o Unsuitable lor track circuited lines.
I Not very suitable for mechanical maintenance.
: More susccptiblc to breakage.
Cast irort slccpcrs rre uscd irt many coLrntries. Type of C.I. sleepers are
J pot type - corrsists of two oval slrape pots.
tr plate type - consists oItwo plates.
Fro. 7-6
C. f. sleeper
Frc. 7-7
bars get bent.

21. I'ltc cr alLrutron ol corlcrctc slccl)els llas Dcott lltattlly uLlc io
-: Econonric consitlcratiotrs couplcd rr'ith thc clentcnts of chatrging traffic pattem.
:r Morcover, a slceper lor long rvclded track has to be heavy and sturdy and should be
capablc ol'ol'ltrirrg latclll lcsistance to tlrc track. Wooden and stcel slcepers wct'c fbund
to hc llcking in ll)csc re(lllirctllcllts.
I;ig. 7-8 shorvs il lypical prc-strcssctl cottcrctc slccpcr.
Reinlorcemen
66a-:iJ F
259cm*----+r j*Xq.-a
Prc-stressed concrete sleeper for British Railways-Class E
Fro. 7-8
Advu tuBcs
jr Conclcte slcepcrs, being hcavy, lend strength and stability to track.
r Concrete slecpers s,rth clastic fastenings provide a track which can maintain better
gaLlgc. cross icvcl attd aligrtntcttt. lt retains packing also very r'r'ell.
r The concrcte slccpcrs, bccause of thcir ilat bottom, are best suited for modern
nrethods oI track nraintctrancc.
o Concrctc slcepcrs carl bL- used ilt
electlicity.
r They are ncither intlarrnrablc nor subjccted to dat.nage by pests or cottosiott in normal
circ ur.ttstances.
The lilc ol'concretc sleepets is very long, probably 40 to 50 years. Rail and sleeper
rcncu'als as such can be rnatched, wltich rs a very big economic advantage.
'l hc cotLcrctc slccpcrs cal gcrtcraily bc ttutss ptotluccrl ll'ortr locll lcsoLlrccs.
Disa vutttugcs
o Handling and laying ol' concrete
Mechanicrl rncthods have to be
considerable initial cxpendittirc.
track circuited areas, being poor conductor of
sleepers is difficult due to their being heavy.
nonnally adopted for handling which involve
c The danrages to coucrete s)cepers is very heavy at the tilne ofderailment.
c There is no scrap value lor the concrete sleepers.

22. Sleeper Density and Spacing of Sleepers
Tlre nunrber of sleepers used per rail length on a track is known as sleeper density. Sleeper
density mainly depends upon:
o Axle load and spccd,
: Type arrd section ofrails,
r Typc and strcngth olslecpcrs,
,-r Type of ballast and ballast cushion,
iJ Naturc of fornration.
The ntorc thc no. olsleepers greater will be the lrteral stability. The no. ofsleepers, horvever,
cannot be increased indclrnitely, since a certain minimum spacing is necessary for packing
the ballast.
It isspecifiecl byM+xorN+xwhereMorNisthelengthofrailinmetresoryardsandxis
lhe n urllber.
In rnetric units, ifslecpcr clcnsity is M + 7 on e Broad Gaugc route and tlte length ofrail is 13
nretrcs, it nlcans tlrat 13 + 7 = 20 sleepcrs will be used per rail. Similaily in F.P.S. Units, il
thc slccpers dcnsity is N + 3 on a M.C. route and the length of rails is 36 11. or 12 yards, the
nunrber ofsleepcrs used is l2 + 3 : 15 per rail length.
l'he number ofsleepers in the track can also be specified by indicating the number ofsleepers
per kln of track, e.g. 1540 sleepers per km. This becomes more relevant pa(icularly in those
cases rvhere rails are welded and length of the rail does have much bearing.
Spocing naar tht' Joints
'[hc spacing is kept unilornt throughout the rail length but is made closer near the joints
o because of thc rveakness ofthejoints
s to give st.rong support against tl.re impact of the moving loads on it and
o to avoid loosening o[ballast due to impact in suspendedjoints
As such, the spacing ol sleepers is not uniform near the joints. Three or four sleepers on
either side of the joints known as shoulder sleepers are kept close together. The details ofthe
spacing are shown in Table 7.1 and Figure 7.1 .
I
,/--

23. Cornparison ol cltaractcristics of dilTcrcnt typcs of slecpcrs
Cltu ructcrstics ['l'oolut Stee I slecpers L'.1. s lcapcrs Concrcte slacpcrs
l. Scrvicq lil'c
2. Wcighr lor B.C.
3. Ilandlrng
-l l'r,pc o1'
nrailltenancc
5. Cost of
ntailttertance
6. Cauee ad justrncnt
7. Track circLriting
E. Danrage by whitc
ants and corrosion
9. S uitability lor
lastening
10. Suitablility to
track
I l. Track clast ic ity
I 2. Creep
13. Scrap valuc
l2 to l51,rs.
83 kg
M an Lral;
No darl;rgc
rvlrilc lt anciling
NIattLral tlr
nr cchan izcd
H i_qh
-=GDil'ficLrTh/
Bcsl
Can bc dantaged
by white ants
Suitablc lor
CF&EF
Suitable lor all
foulcs*
Good
Crcep is
cxcess ive
Low scrap valuc
3U to -10 yrs.
179 kr
lu,'nurt ;
lNo danra-ge
lrr h r lc hrnd linu
I
lMrrr,r.il ,,,.
lnrcchanized
I
Mediunr
t-- ._--
lEasv
I
lDiificLrlt;
I lnsLr Illt ins nads
lrr"
n"..rlrrv
No darlage but
corToston rs
possible
Suitable for
CF&EF
Suitable lor all
routes
Good
Less creep
Highcr scrap
value than
wooden sleeper
140 to 50 vrs.
lr, *n
1r,,,1,,,,
lLiablc to break
bv ro Lt ult hrnd Iin l
1r"","].,,,
I
Medium
!-.
lEasy
I
t_--
lDl ttl c Ll lt.
llnsuletinB
pads are
nec csse ty
Canoe dantaged by
coIroston
Suitable for
only CF
Not suitable 1br
hrgh speed routes
High scrap vahre
Good
Less creep
50 to 60 yrs.
267 kg
Mcchanized;
Gets dauraged
by rough hand lrng
Mechanized only
Low
No adiustmer.rt
possib le
Easy
No damage by
white ants or '
corrosion
Suitable for
only EF
Suitable for high
speed routes.
Best
Creep is
minimum
No scrap value
t Also suitablc lbr track circuititrg, lcvcl crossing and poinrs & Crossings... Large nunrber ol.anchors required to prevent &cessive crrep.
CF stands lbl convcntional lastcning & EF stands for elastic fastening.
{/
I
{

24. 'fable 7.1. Spacing of Sleepers (Fig. 7.1)
Spucing of Sleepers Metre Gauge centre lo
centre spacing in cm
Wooden Metal
25
58
70
(62)*
82
(72)*
3.
Between joint slecpcrs (a)
Between joint sleepers ar.rd the first
shoulder sleeper (b)
Betwecn lst shouldcr slecpcr and 2nd
shoulder slccper (c.1 lbr sleePer
dcnsityM l-4andM+7*
Between intcmlediatc sleepers (d) for
sleepers density M +' 4 ar.rd M + 7+
+ The spacing is lor slecper density M + 7
Nores .. (i) The spacing lor joint sleeper (a) and the lst shoulder sleeper (b) will always
remain thc sarltc as givcn above for all length of rails and all sleeper densities. The
spacing (d) shoulcl bc rvhole numbcr o1'cr.n aud spacing c should be betwcen b and d.
(ii) In case of long welded rails on BC arld MG, the sleeper spacing is kept 65 cm'
L{I'EIIED ME
*#Zf 'p{iZ'l'l9Sl"l3ltl*'#J:i'iJ'S{k'*TH'#fl'
33
58
1t
(60) n
8i
(64)*
Fig. 7.1. Spacing of Sleepers at Fish Plted Track
Broad Gauge centre to
cetire spacing in cm
30 38
61 61
70 72
(64)* (63)*
84 83
(68)* (68)*

25. (f nanast
Delin ition
Ballast is a layer ol'brolicn stone, gravcl or any other granular matenal placed and
packed below and around sleepers for distributing the load from the sleepers to the formation
and for providing drainage as wcll as giving longirudinal and lateral stability to rhe track.
Sleeper
Slope
ofl tol
ot
t!rc t
Ballast section
Frc. 8-l
FIC-A,2 BALIAST PROFILE FOR BG SINGL.E UNE FOR FISII PIATED TP./.CT
Functions of Ilrll^st
(i) To provide a level and sound foundatron for the sleepers to rest on.
(ii) To lrold thc slccpers in position during the passage oftrains
(iii) 1'o transfcr and distribute the load from sleepers to a large area of formatiolt.
(iv) To provide elasticity and resilience to track for getting proper riding comfort.
(v) To provide necessary resistance to track lor longitudinal and lateral stability.
(vi) To provide elfective drainage to track and keep the sleepers in dry condition.
(vii) To provide effective means ofmaintaining level and alignment ofthe track.
(viii)To discourage the growth ofvegetation.
Requirements of good Ballast
(i) lt shoLrld be tough and wear resistant.
(ii) It should not be brirtle,
(iii) tt should be hard enough so that ir is not crushed under the moving loads.
ii
'
/c c)
'g"--Vo o o ^oo
<>" o o
3-3:3'i;.
c>
o <=, ooolo,

26. " ..
(iv) lr shoultl bc dLrrable and should not gct pulvcrized under the weather conditiotls.
(v) lt should be generally cubical in shape with sharp edges so that they can
sufficient grip over the sleepers to prevent their horizontal movelllent'
(vi) It should bc notl-porous and Ilon-absorbcnt of watcr'
(vii) lt should provide good drainage of water.
(viii) lt should be cheap and easily available.
T1'pe of Ballast
foilo*'ing materials are uscd as ballast in a raihvay track:
(i) Broken stone
( ii) Gravel
(iii) Ashes or cinders
(iv) Coarse Sand
(u) Kankar
(vi) Moorum
(vii) Brickbats
(viii) Selected earth.
(l) Broket stoua:
This is the best material lor perfonning the lunctions of ballast in a railway track.
Almost all the important tracks are provided with stone ballast. The stone to be used as
ballast must be haia, tough, non-porous and should not decompose rvhen exposed to air and
danrpness. Cranite lulfilli these conditions. But due to consideration of availability, quartzite,
sandstorle and linrcstonc arc also used as ballast. Initial cost of the material is high. But it
kecps the triick in bctter position, cspccially undcr heavy traflic.
(2) Gruvel:
Gravel comes next to broken stone and it is used in many countries. It consists of wom
fragments of rock occurring in natural deposit. It is obtained from river beds or gravel pits
along the track,
Ath,ttnlages:
(a) It is cheaper tharr stoue ballast.
(b) The drainage property is excellent.
Di.t(l'0 n ta gc.:
(a) It casily rolls down duc to vibr-ations and the packing under the sleepers gets'loose.
(b) Variation in size is considerablc and hcnce, it requires screening before use
(3) Ashes or ci,tders:
The residue from the coal used in locomotives
cinders and this is one of the most universal forms
railway which uses coal as fuel.
and other fumaces, is known as ashes or
of ballast, since it is by-product of every
ti wrntages:
(a) - ris nraterial has got fairly good drainage properties.
(b) Handling of tl.ris matcnal is not cumbersome
(c) The cost ofnraterial is low.
(d) The nraterial is available in large quantities at short notice.
Dr Md. Sha,Jsul Hoque
{

27. {
Disutlvu tt tuge-s .'
(a) This material is r,ery sofi and it gets easily reduced to powder and heilce, the track
beconrcs vcry dusly. This is objcctronablc cspecially in dr.y wcather.
(b) This ballast has got conosive qualiry and hence, this is not used where steel
sleepers are flxed.
(c) The foot of the rail gets aflected where this type ofballast is used.
(4) Sand:
Sand lorns anothcr good ballast nraterial. Coarse sand is to be preferred to fine sand.
.,11t'u rtlctgcs:
(a) lf the sand is fiec lronr eiirth and vegetables, it has got excellent propefiies to drair.r
olT wal.er irnntcdiately.
(b) This rraterial produces a silent track and has been found very good for packing
casl- irou pot sleepers.
(c) It is chcap, ifavailable in nearby locaiity.
D$dlld tagcs;
(a) Sar.rd ballast rerluires fi"equent rcnerval as sand can be easily blown off or washed
away
(b) Sand is disturbcd casily by vibration and hence, the maintenance oftrack becomes
vcry drlficLr h.
(c) Sand gets into the nroving parts of the vehicles and causes friction. This Ieads to
hcavv wcar of vch iclcs.
(5) Kankar:
Kankar is found * many places in the fomr of nodules of varying sizes. It is useful
where other suitable uraterial for ballast is not available and also, on light tralfic on metre
gauge and narrow gauge. Kankar tums down to powder very easily and lrence, the
nraintenance of the track becomes very difficuit.
(6) Moontm:
Deconrposition of laterite rcsults in the fomlation of moorum. It has a red and sornetimes
a ycllo* co lou r.
,llvuntages..
(a) Moorunr can salely be used on newly laid tracks and it will act as soling when the
stone ballast is laid afterwards-
(b) Moorum has got good drainage properties.
Disutlvutttuges;
(a) Moorum is soft and it turns into dust in very short time.
(b) Maintcnancc of rlack laid with this material as ballast becomes vcrv difficult.
(6) IJrickbats:
Sometimes, brickbats ofoverburnt bricks are used as ballast.
t? Dr. ltld. Shansul Hoque

28. ,d
Adva lugcs:
(a) Brickbats arc uschrl in places where suitable rnaterials lor ballast are not available.
(b) Brickbats havc gr.rt lairly good drainagc propcrtics.
Dis(dru tuges:
(a) Brickbats turn dowt'l into powder lorm very easily and
(b) it becoues very difficult to maintain the track in
the track becomes dustY.
good condition where this
ruraterial is used as ballast.
(c) Rails are olten corrugated ou the track laid witir ballast ofbrickbats.
(8) Selected earth:
For sidings and also for newly laid railway tracks, selected earth is sometimes used as
ballast.
Minimum depth of Ballast Cushion
The depth ol the ballast is dcflncd as the distance between the bottont of sleeper and top of
subgrade. This depth of ballast is very important in deternlining the carrying capacity of the
track.
The loacl conting on the sleeper is transferred through the medium ofballast to the formation.
The pressure distribution of the ballast section depends ripon size and shape of ballast and
dcgree ol consolid:rtior.r etc. Through the lines of equal pressure are in the shape of bulb, yet
foi simplicity, the dispersion of load can be roughly assumed at 45 degree to the vertical. In
order to cnsurc that thc load is translcrrcd cvcnly otr thc lon.ttatiott, the dcpth of ballast should
be cnouglr so that dispcrsion lines do not overlap each othcr.
FIG. A.I MINIMUM DEPTH OF BALIAST CUSHION
It can be proved by a simple geometry that for even distribution of load on the formation, the
depth ofballast is given by the fonnula.
Sleeper spacing: Width ofthe sleeper + 2 x depth ofballast.
Assuming that the track is laid with woodon sleepers to N + 6 slecper densrly, thc slccpcr
spacing is ],5" and width of sieeper is 10", the minimum depth of ballast fi'om the above
consideratioir comes to 7 112'. A rninimum cusliion of 15 to 20 cm. (6" to E") of ballast below
the sleeper bcd is, therefore, nomrally prescribed.
Dt. M.l. Sh.,nsul Lloque
J'1'. '
Y"

29. Spccification of Stone Ilallast
Pht'sicrtl propartics of btllust:
0 Qualit.y of Truck ballusr
fract-Uattait ihould be obrained iiom good quality stone and top layer, if weathered, must
not be used. Track ballast sl.rould consist of hard and rlurable stone and sl.rould confom to the
upproYe<t samples. Track ballast should not contain inorganic or organic residues and must be
lrcc lrorn infcrior and harnilul substances.
(iii) Elongatiort, Flakiness Speciftc gruvitl' and absorption properties
(ii) Si:e untl Gradatiotr of Ballast:
a) Retained on 65 mnl square me sh:
b) Retained on 40 nttn square nlesh:
c) Retained on 20 mnl square mesh:
ballest
T)'pe of te st
a) Elongation Indcx
b) Flakiness lndcx
c) Specific gravitY
d) Water absorPtion
Meclrunical properlics of ballast:
T1'pe of test
a) Aggregate Abrasion valucs
b)Aggrcgllte InlP:rc t tcst
NIL
55% to 10%
Not less than 100% for machines crushed
Re commended. Value
Maximum 507u
Maxir.num 500%.
Minimum 2.65
Maximum 1o%
Reconrmended Value
Maximum 3070
Maximum 207o.
Ballast section
Frc. B-2
Droin
Ballast section
Fro. B-3
,{::r:t'":"-'i:::b>:.,-'a)

30. ..."=
Subgrade and Formation
Definitions
tl SttbgrctLle;strbgradc is rronnally dcfined as thc naturally occurring soil.
ri) Intli.ot,ad Suttgr.ude . Natural sirbgrade which can be fLrrther prepared to receive the
b a I last.
iii) Formution. The prcpatcd
and rails is callccl tlrc
embartknrcnt or a c Ltttin g.
ir,) En ;urtkntcn /r whelt the fbrrnation is in the siiape of raised bank consLructed above
the natrlral ground, it is callcd an Ernbankment.
v) Cutring'. lV-hen thc formation is at a Ievel below the natural ground, it is called a
culting: Nornrally cuttirlg or excavation is nrade through a hilly or natural ground for
provrding the railway line at the required level below ground level.
Iiunction of Fonnation
The fonnation has the following lirnctions:
i) To provide a snrooth and unifomr bed on which track can be laid.
ii) To bear the vertical load of moving trains.
iii) To rcducc the intcnsity of load at natural sub-grade level.
iv) To keep the track above flood Ievel.
v) To providc stability to thc track.
Emban knrent Geontett'y
o The height of lbrnration depends upon the ground contours, highest flood level (HFL)
and the gradrents adopted.
o The width of the lonnation depends upon the number of track'to be laid, gauge and
such other factors.
o The side slope of the embankment is dependent upon the shearing strength of the soil
and its angle of repose. To prevent erosion of the side slopes due to rainwater, rvave
actioll e1c., tire side slopes are turled with a thin layer of cohesive soil or alten.ratively
with suitablc tyl.rcs of grass. Sometimes, a toe wall is provided at the bottom of the
embankmcnt to plevcnt sliding of soil.
Blanket Layer
Blanket can bc deflncd as an intervening layer of superior material rvhich is provided just
undcrlcatlr tlre billlast cuslrion. lt is dilfcrent fron sub-ballast rvhich is provided above the
lorniation. The [unction ol the blanket are two-fold:
(a) To mrnimisc the puncturing of stone ballast into the formation soil.
(b) To reduce the ingrcss o f rainwater in the formation soil.
The blanket should generally cover the entire width of the formation. The depth of the
blanket should normally be about 30cm in ordinary clay soil. However, if formation soil is
parlicularly wcak, a thicker layer upto 60cm may be necessary depending on the shear
propcrties of thc lormation soil.
'l'cchniques to I rnproYc Embaukment Stability.[-here
are varit.rus methods to improve the stability olrailway embanl(ments:
i) Flutten sidc slopes: This provides better stability particularly when there is
iailure due to fill nlaterial
it) Intprovc tlrainage:
-Ihe
drainage gets improved by providing surface and sub-
surlace cir:rins.
iii) Provisron of sheet piles: Sheet or ordinary piles are provided on either side of
ernbankrnent to cheek the shear failure and improve stability.
iv) Scnd drains: This helps in quicker consolidation of ernbankment.
tlat surface, rvhich is rcady to receive the ballast, sleepers
lbrnration. 'l'hc tbrntatior.t can be it.t the shape of an
Dr Md. Sh/.trtsul lloque

31. {
) Itiver!(tl fittcr. A blarlkct of adequalc thickness or illvetlctl filtcr is providcd
)
;:ii"";;; 11.,iirt, ,,,.1-*"rr for:'ration to improve stahilitv
,.'i) Ct'rrcrrt s,rotttittg:irrlt]lLUii'i" I*p't"ini tr'" stahiIitv"of the bank'
lii) !;;;;;;,/i;;.
:irh"'
';;;J
pit'i' (ro"pl"t tlre-soii and pr6vide mechanical support 10
,,,,.,
tlll*,),1.0,,i-
tt of soir: Che,.rical a,d mechanical srabilization l.ras the potential to
inrurove stability o l' thc entbattknrent'
irt Giorett ile,".l,,,,q,l"r li1,iJr.,.ipt 1,,,'i*p.'ing dri'inage and provide resistance to
thc soil bed and thcreby inrprove the slablllly
t"il':.:i:lif;::'lii
3,l,,",,ilji.tjl'li.>oir has rcccnrry been gg.,qlop"a in mrnv
:::,il,l::.:,f
,h"
rt.rtrt bv usc ol.Cl-OTE I f LLBI iiiir',*'* 'rri.i;,ri "
U^i.ullv'rttrdc trp ol polyurcr. irrrd lrrs
uniquc properry ol.ullo$ing r rr?"r, rt"i"ro fasr itriougtr but noi iire soil fines. ceotextiles r.r ork
not only as sepalalors ono
"'it"
n" il'L a'uin thE water and provide reinforcemellt to the
soil bed.
Allyerofgcotextilclsnorrrtallyl;rideitherdirectlybelowrhehallast.sometimesitrslaidas
sandu,iched betrvceu rry",. oi'r'",,i'lo iii"i u.ri.r, does nor reir airectty on the ceotextile and
il;1";td;;." of te ar and purlcture gets redr-rced
BALLAST
t-t<;- 9.7 FUNCTIoNs oF aEot'Ex'|-ILES
r!,IOISTUHE
rta. 9.E LIvNA l)l Gtol LrnLEs
MOISTURE
TBAN9POBTED
ALONG PIANE
OF FABAIC &
THROUGH
AALLAST
SOIL FINES
RETAINEO
SELOW FABRIC