Solved Question Papers Transportation Engineering II

8/16/2019 Solved Question Papers Transportation Engineering II

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Solved Question papers Transportation Engineering II

1. Explain the role of rail Transportation in the development of country (8 Marks)

Since its creation Indian Railways has successfully played the role of the prime carrier of

goods and passengers in the Indian Subcontinent. As the principal constituent of the nation’s

transport infrastructure the railway has important role to play.

!. Railways provide the cheapest and most convenient mode of passenger transport both for

long distance and suburban traffic.

". Railways have played a significant role in development and growth of industries. #rowth

of te$tile industry in %umbai &ute industry in areas surrounding 'ol(ata coal industry in

)har(hand etc is largely due to the development of railway networ( in these areas. Railways

help in supplying raw materials and other facilities to the factory sites and finished goods to

the mar(et.

*. Agriculture also owes its growth to railways to a great e$tent. +ow farmers can sell their

agricultural produce to distant places and even sell them in the world mar(et at remunerative

prices.

,. Railways are also helpful in removing isolation between cities and countryside and have

played a significant role in disseminating innovations and new ideas.

-. Railways are particularly suited to long distance &ourney and provide a strong medium of

national integration.

. Railways play a vital role in mitigating the sufferings of the people in the event of natural

calamities li(e droughts floods famines earth/ua(es etc. This is done by carrying relief and

rescue teams and essential items to the affected areas and save people from sufferings andstarvation.

0. Railways also help in facing man1made calamities li(e social political religious

disturbances insurgency etc. It facilitates easy movement of police troops defence

e/uipment etc. The importance of railways to save the country’s freedom and integrity from

e$ternal aggression has been proved at several occasions.

2. Railways carry the 3ritish legacy and connect ma&or ports thereby lending a helping hand

to the overall prosperity of the coastal areas.

4. Introduction of superfast trains and container services in ma&or cities of India have ensured/uic( movement of men and material.

!5. Railways are especially suited to long haulage of bul(y materials li(e coal petroleum and

ores.

2. What are the different types of rails used in ndian rail!ays" Mention their

advanta#es.

There are mainly three types of rails used

!. 6ouble headed". 3ull headed


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*. 7lat footed

The first rails used were double headed 869: and made of an I or dumb1bell section 87ig.

.!:. The idea was that once the head wore out during service the rail could be inverted and

reused. E$perience however showed that while in service the bottom table of the rail was

dented to such an e$tent because of long and continuous contact with the chairs that it wasnot possible to reuse it. This led to the development of the bull headed 839: rail which had

an almost similar shape but with more metal in the head to better withstand wear and tear

87ig. .":. This rail section had the ma&or drawbac( that chairs were re/uired for fi$ing it to

the sleepers.

$ flat-footed rail 87ig. .*: with an inverted T1type cross section of inverted T1 type was

therefore developed which could be fi$ed directly to the sleepers with the help of spi(es.

Another advantage of the flat1footed rail is that it is a more economical design giving greater

strength and lateral stability to the trac( as compared to a 39 rail for a given cross1sectional

area. The flatfooted 877: Rail has been standardi;ed for adoption on Indian Railways.

%ou&le 'eadedThey mainly have * components

!.


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-. The trac( should be resilient and elastic in order to absorb shoc(s and vibrations of running

trac(.

. The trac( should have enough lateral strength so that alignment is maintained even due to

effects of

a. Side thrust on tangent lengths and centrifugal force on curves

b. >ateral forces due to e$pansion of rails particularly in case of welded rails0. The radii and superelevation on curves should be properly designed and maintained

2. 6rainage system must be perfect for enhancing safety and durability of trac(

4. )oints including points and crossings which are regarded to be wea(est points of railway

trac( should be properly designed and maintained

!5. If there is trouble from the creep the preventionary measures should be to prevent it

!!. The various components of trac( i.e the rails fittings sleepers ballast and formation must

fully satisfy the re/uirements for which they have been provided

!". There should be ade/uate provision for easy renewals and replacements.

!*. The trac( structure should be strong low in initial cost as well as maintenance cost.

+. %ra! neatly the cross section of a strai#ht ,road -au#e ail!ay Track in

/uttin# for %ou&le 0ane and in#le 0ane in Em&ankment

. %efine creep. What are the possi&le causes and effect of creep"


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/reep of rails

reep is defined as the longitudinal movement of rails with respect to the sleepers in a trac(

Indications of creep

!. losing of successive e$pansion spaces at rail &oints in the direction of creep and

opening out of &oints at the point from where the creep starts

". %ar(s on flanges and webs of rails made by spi(e heads by scraping or scratching asthe rail slide

The main factors responsible for the development of creep are as follows.

ronin# effect of the !heel The ironing effect of moving wheels on the waves formed in the

rail tends to cause the rail to move in the direction of traffic resulting in creep.

tartin# and stoppin# operations =hen a train starts or accelerates the bac(ward thrust of

its wheels tends to push the rail bac(wards. Similarly when the train slows down or comes to

a halt the effect of the applied bra(es tends to push the rail forward. This in turn causes creep

in one direction or the other.

/han#es in temperature reep can also develop due to variations in temperature resulting inthe e$pansion and contraction of the rail. reep occurs fre/uently during hot weather

conditions.

3n&alanced traffic In a double1line section trains move only in one direction i.e. each

trac( is unidirectional. reep therefore develops in the direction of traffic. In a single1line

section even though traffic moves in both directions the volume of the traffic in each

direction is normally variable. reep therefore develops in the direction of predominant

traffic.

*oor maintenance of track Some minor factors mostly relating to the poor maintenance of

the trac( also contribute to the development of creep. These are as follows.

8a: Improper securing of rails to sleepers

8b: >imited /uantities of ballast resulting in inade/uate ballast resistance to the movement of

sleepers

8c: Improper e$pansion gaps

8d: 3adly maintained rail &oints

8e: Rail seat wear in metal sleeper trac(

8f: Rails too light for the traffic carried on them

8g: Bielding formations that result in uneven cross levels

8h: @ther miscellaneous factors such as lac( of drainage and loose pac(ing uneven spacing

of sleepers.

Effects of /reepThe following are the common effects of creep.

leepers out of suare The sleepers move out of their position as a result of creep and

become out of s/uare. This in turn affects the gauge and alignment of the trac( which finally

results in unpleasant rides.

%istur&ance in #aps. 6ue to creep the e$pansion gaps widen at some places and close at

others. This results in the &oints getting &ammed.


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%ifficulty in chan#in# rails If due to operational reasons it is re/uired that the rail be

changed the same becomes difficult as the new rail is found to be either too short or too long

because of creep.

Effect on interlockin# The interloc(ing mechanism of the points and crossings gets

disturbed by creep.

*ossi&le &ucklin# of track If the creep is e$cessive and there is negligence in themaintenance of the trac( the possibility of buc(ling of the trac( cannot be ruled out.

4ther effects There are other miscellaneous effects of creep such as brea(ing of bolts and

(in(s in the alignment which occur in various situations.

5. Mention the advanta#e of havin# uniform #au#e in the country

#auge to be used in a particular country should be uniform throughout as far as possible

because it will avoid many difficulties e$perienced in a non uniform system. The uniformity

of gauges results in the following advantages.

!. The delay cost and hardship in transhipping passangers and goods from the vehicles of one

gauge to another is avoided.

". As the transhipping is not re/uired there is no brea(age of goods.

*. 6ifficulties in loading and unloading are avoided and labour e$penses are saved.

,. ?ossibility of thefts and misplacement while changing from one vehicle to another is

eliminated

-. >arge sheds to store goods are not re/uired

. >abour stri(es etc. do not affect the service and operation of trains

0. Surplus wagons of one gauge cannot be used on another gauge. This problem with not arise if

gauge is uniform

2. >ocomotives can be effectively used on all the trac(s of a uniform type of gauge is adopted.

4. 6uplication of e/uipment such as platforms sanitary arrangements cloc(s etc. is avoided.This saves a lot of e$tra e$penditure

!5. 6uring military movement no time is wasted in changing personnel and e/uipment from one

vehicle to another if gauge is uniform

!!. It is /uite e$pensive to convert one gauge into another at a later stage as it may re/uire new

rolling stoc( fresh construction and widening of bridges and tunnels.

!". 6ue to late arrival of trains at the &unction where change of gauge is involved the missing

lin(s results in number of difficulties.

6. %ra! a neat sketch of dou&le line ,.- track /ross section in curves. Mention

various component parts.


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Rigidity %ore rigid They are less rigid

Inspection 6aily inspection is not necessary 6aily inspection of wooden

(eys is necessary

%aintenance cost Is less %ore

Suitability %ore suitable because of better

stability economy strength and

stiffness

%ore suitable at places where

lateral loads are more

important rather than vertical

loads

9.9 rails

Merits

!. They have more strength and stiffness both vertically and laterally than 3.9 rails

". 7itting of rails with sleepers is simpler so they can be easily laid and relaid

*. +o chairs or (eys are re/uired as in case of 3.9. Rails

,. In points and crossings the arrangements are simpler than 3.9. rails

%emerits!. The fitting get loosened more fre/uently than in case of 3.9 rails

". The straightening of rails replacing of rails and dehogginf of battered rails are difficult

,.' rails

Merits

!. They (eep better alignment and give more solid and smoother connection with the latter

". The heavy chairs with larger bearing on sleepers give longer life to wodden sleepers and

greater stability

%emerits

• They re/uire additional cost of iron chairs

• They have less strength and stiffness

• They re/uire heavy maintenance cost

6ouble .9eaded

As in double headed rails does not have any advantages as the main concept of using a

double head in the rail failed due to the damages caused on the lower end or the rails due to

fastening

%emerits

• They re/uire additional cost of iron chairs

• They have less strength and stiffness

• They re/uire heavy maintenance cost

1;. What is conin# of !heel" What are the advanta#es of conin# of !heels

The head of the wheels of railway vehicle are not flat but made sloped and this sloping of

surface along the circumference forms a part of a cone. @n straight trac(s the coning of the

wheels (eep them centrally thereby reducing the wear of wheel flanges. If at any movement

the wheels go out of the central portion then they have to travel une/ual distance due to the

change in diameter of inner and outer wheel thus forcing it bac( to the central position and

hence the ride will be smoother.


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The problem however arises in the case of a curve when the outer wheel has to negotiate

more distance on the curve as compared to the inner wheel. 6ue to the action of centrifugal

force on a curve the vehicle tends to move out. 9ence the conning of wheel helps in outer

wheel to travel larger distance since it has larger diameter of the wheel and the inner wheel

will travel smaller distance because it has smaller diameter of wheel. The wheels of a railway

vehicle are connected by an a$le which in turn is fi$ed on a rigid frame. 6ue to the rigidity

of the frame the rear a$le has a tendency to move inward which does not permit the leadinga$le to ta(e full advantage of the coning. The rigidity of the frame however helps to bring

the vehicle bac( into central alignment and thus wor(s as a balancing factor.

@n rails laid flat conning of the wheels will sub&ect the rails to eccentric loading at the inner

edge. This would create problem in both rail design and maintenance. To avoid this rails are

not laid flat but they are instead tilted inwards at a slope of !C"5. =hich is the slope of wheel

cone. This is called as canting of rails.

oning of wheels causes wear and tear due to the slipping action. It is however useful as

8a: It helps the vehicle to negotiate a curve smoothly

8b: It provides a smooth ride and

8c: It reduces the wear and tear of the wheel flanges.

11. ketch the rail sections !ith dimensions. %iscuss the criteria for decidin# the

cross section and len#th of rails.

a: -" (g rail b: 5 (g rail


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The length of rail depends upon the ma$imum length1 si;e that manufacturers can produce at

a reasonable cost. >onger rails lengths re/uire e$pensive arrangements at the rail mills for

their controlled cooling stac(ing and handeling. Another limiting factor is the problem of

transport. Theoretically the longer the rail the lesser the number of &oints and fittings

re/uired and the lesser the cost of construction and maintenance. >onger rails are economical

and provide smooth and comfortable rides. 9owever the length of rail is governed by the

following considerations

!. The length of rail which can be manufactured at the reasonable cost

". The rails should be of such length that they may be carried in the largest wagon

available

*. The length of rail is also limited by the facilities available for lifting or handling the

rail

,. The length of shortest rail should be larger than largest rigid wheel base of wagon

The length of a rail is however restricted due to the following factors.

8a: >ac( of facilities for transport of longer rails particularly on curves.

8b: 6ifficulties in manufacturing very long rails.

8c: 6ifficulties in ac/uiring bigger e$pansion &oints for long rails.

8d: 9eavy internal thermal stresses in long rails.

Ta(ing the above factors into consideration Indian Railways has standardi;ed a rail length of

!* m 8previously ," ft: for broad gauge and !" m 8previously *4 ft: for %# and +# trac(s.

3ut Rail weld or rail &oint is the (now ;one of wea(ness in trac( structure hence should

avoided to the e$tent that is possible. The rolling of rails in longer length is therefore

encouraged. The new rail rolling set up by ;indal steel and power lmd in india is rolling railsupto length of !"5 m each.

Wei#ht of rail

Though the weights of a rail and its section depend upon various considerations the heaviest

a$le load that the rail has to carry plays the most important role. The following is the thumb

rule for defining the ma$imum a$le load with relation to the rail sectionC

%a$imum a$le load D -5 sectional weight of rail in lbs per yard or (g per metre

12. What is meant &y !ear of rails" 'o! do you classify the !ear" %iscuss the

various causes of !ear"

Type of Wear on ails

/lassification &ased on location

!. @n sharp curves

". @n gradient

*. @n approaches to stations where bra(es are fre/uently applied

,. In tunnels

a. =here sand is used on rails to produce more friction on damp rails but on the

contrary it gives more wear

b. In tunnels the gases emitting from the engine being confined attac( the metal

and results in wear.

-. In coastal area due to action of sea bree;e the corrosion of metal ta(es place


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. @n wea( foundation1 sin(ing of rails due to heavy loads gives uneven surface which results

in wear

@n bases of portion of wear

!. =ear on top of head of rail

". =ear at the ends of rails

*. =ear on the sides of head

Wear on top of rails

!. 6ue to flow of metal1 this is because the heavy loads concentrated on small area produce the

stresses which e$ceed the elastic limit and hence plastic flow of metal ta(es palce and burrs

are formed which later get chipped off by moving wheel flanges

". and its recurring impact causes the wear at the top pf rails

*. 6ue to abrasion of rolling wheels the rails generally get worn out at the top of rails

,. 6ue to constant bra(es application which results in s(idding and burning of the rail head.

This finally results in e$cessive wear and abression

-. 6ue to use of sand which is spread to produce friction in case of dampness in tunnels. The grinding

action of sand particles with rails gives rise to wear.

. 6ue to fluctuations in gradients.

0. 6ue to corrosion of rails by the action of sea bree;e which also gives rise to wear on top

of rails.

2. 6ue to wea( trac(s vi;. loose pac(ing of ballast or loose fitting of rails and sleepers increase

war.

4n curves.

The wear on top of rails at curves is die to the following causes

!. 6ue to slipping or s(idding of wheels

". 6ue to effect of centrifugal force and improper superelevation load on one rail is greater thanthe other. If superelevation is more or less for a given speed the load will be more on inner or

outer rail respectively

*. 6ue to ad;ing of sleepersC on curves the sleepers have to be laid at a slope for the purpose of

superelevation but when the rail is laid at a slope of ! in "5 on sloping sleeper the resulting

slope or tilts s different from the slope of wheel cone giving lesser a of contact between the

wheel and the rail resulting in more wear due to heavy concentration of stresses

Wear at ends of rails

This type of wear is encouraged due to following factorsC!. 6ue to loose fish plates and fish bolts

". 6ue to heavy loads and larger &oint openings

*. 6ifference in rail levels at &oints

,. Small wheels

-. 3ad condition of the vehicle springs

. ?oor maintenance of the trac(

Wear on sides of the rail head<

This type of wear is only prominent when the rails are laid at curves. This type of wear is

more than first two types of wear and is most distructive in nature. This wear occurs due to

following causes


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!. At curves there is greater thrust on inner rail when trains run at lesser speed than

e/uilibrium speed

". due to rigidity of the wheel base

*. slipping and s(idding of wheels at curves.

1. %ra! a neat sketch sho!in# the details of dou&le line ,.-. track !ith electrical

traction

1+. %ra! a typical /ross section of a permanent !ay. %iscuss in &rief the &asic

functions of various components of rail!ay track.

7ig C Typical ross section of a permanent way on emban(ment

The combination of rails fitted on sleepers and resting on ballast and subgrade is called therailway trac( or permanent way. Sometimes temporary trac(s are also laid for conveyance of

earth and materials during construction wor(s.

In a permanent way the rails are &oined in series by fish plates and bolts and then theya are

fi$ed to sleepers by different types of fastening. The sleepers properly spaced resting on

ballast are suitably pac(ed and bo$ed with ballast. The layer of ballast rests on the prepared

sub grade called the formation.

The component of permanent way include

!. Rails

". Sleepers*. 7asteners


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,. 3allast

-. Subgrade

The rails act as girders to transmit the wheel load to the sleepers and also it provides level

surface for train movement.

The sleepers hold the rails in proper position with respect to the proper position with respect

to the proper tilt gauge and level and transmit the load from rails to the ballast.

In a permanent way the rails are &oined in series by fish plates and bolts and then they are

fi$ed to sleepers by different types of fastening.

The ballast distributes the load over the formation and holds the sleepers in position.

Subgrade transfers and distributes load to soil layer

@n curved trac(s super elevation is maintained by ballast and the formation is levelled.

%inimum ballast cushion is maintained at the inner rail while the outer rail gets more ballast

cushion. Additional /uantity of ballast is provided on the outer edge of the trac( for which the

base width of the ballast is (ept more than for a straight trac(.

1. Mention the Economic political and social si#nificance 4f ail!ays

Economic i#nificance

Indian railways is the bac(bone of the country’s economy. Its role as a service provider and

the nation builder is all penetrating. It has unfailingly ensured that fruits of development are

distributed far and wide within the country. It facilitates large scale production by increasing

mobility of raw materials wor(ers consumption of heavy bul(y and perishable commodities

by cheap and speedy transportation. Railway have contributed to time1 distance convergence.

It has introduced competition and bring stability and uniformity in prices. Since the railway

ownership is within the control of union government it may be better utilised in accordance

with developmental needs public welfare national security and defence.

*olitical si#nificance

!. There is a strong lin( amoung various parts of the country with a good networ( of

rails. Today India is held together by the railways which roll day and night cuttingacross racial and regional barriers. It has forged bonds of unity and brings different

cultures an people together

". It contributes for national defence through provision of logistic support

*. 6evelopment of railways and the colonising activities has gone hand in hand

,. Railways help maintenance of internal security law and administration

ocial si#nificance

Railways have greatly influenced social life and brought revolutionary changes in social

values beliefs contacts and way of living. 3efore development of railways social life was

local in character. It has promoted social mobility of people. 7re/uent mi$ing of people

brea( short sighted social values and new social values has emerged based on reason and


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scientific thin(ing. ?ersons of different caste creed colour language and religion come into

contact which strengthens brotherhood and social mingling

3nit 2

1. Explain !ith a neat sketch the important features of cast iron sleepers

ST14 Sleeper has got following features

!. The tie bar is fastened to the plate by means of four standard cotters. Small variation

in gauge can be corrected by these four cotters

". The shape of cost iron support os such as to give a stable base for the rail and high

lateral and longitudinal stability to the trac(

*. The sleeper may be used in sections of trac( in corrosive conditions such as saline

soil industrial waste etc

,. The bearing area is appro$imately e/ual to the effective bearing area of a wooden

sleeper

-. This sleeper forms the rigid trac( sub&ected to vibrations under moving loads without

any damage or absorption

. The cantilever ends of the rails are long which lead to battering and ultimately

hogging of the rail end and deterioration of ballast under the &oint which finally needthe replacement of sleeper.

0. This type of sleeper is suitable for speeds upto !!5 '%?9

2. If used for trac(s above speed of !!5 (mph due to the shallow depth of the bowl

pac(ing becomes loose under vibrations at high speed

As the sleeper does not have a flat bottom it is not /uite suitable for mechanical maintenance

with tie tamers.

!. The suitability of a ST14 sleeper on >ong =elded Rails 8>=Rs: particularly on the

breathing lengths is doubtful because of rigid fastenings and the inability of the

fastenings to hold the rail with a constant toe load.

". The rail seat wears out /uic(ly causing the (eys to come loose.

*. The sleeper has only limited longitudinal and lateral strength to hold >=Rs particularly in the breathing length.


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,. 6ue to the use of less metal under rail seat the shoc(s and vibrations are directly

transmitted to the ballast resulting in poor retention of pac(ing 8loose pac(ing: and

hence an increased fre/uency of attention.

2. With neat sketches explain the various types of spikes and also mention thereuirements of #ood spike

The re/uirements of a good spi(e are

!. 7irst of all the spi(e should be strong enough to hold the rail in position and it should

have enough resistance against motion to retain its original position so that it does not

lead to creep

". The spi(e should be as deep as possible for better holding power

*. The spi(e should be easy in fi$ing and removal from the sleepers

,. The spi(e should be cheap in cost

-. It should be capable of maintaining the gauge

%o# spikes

7or holding the 7.7. Rails to a wooden sleeper dog spi(es are commonly used. These are

simply stout nails to hold rail flanges with timber sleepers. The shape of head of spi(e

resembles with ear of the dog and hence its nomenclature as dog spi(e. The section of the

spi(e is s/uare1shape and bottom part is either pointedblunt or chisel shaped. They are

cheapest easy in fi$ing and removing from sleepers and maintain a better gauge than scre

spi(es.

cre! spikes

These are tapered screws with F threads used to fasten the rails with timber sleepers. Thehead is circular with s/uare pro&ection

Screw spi(e has double the holding power as that of dog spi(e an can also resist lateral thrust

in a better way as compared to dog spi(es. 9owever the screw spi(es are costly and with that

their use the gauge maintenance become difficult

ound spikes

Round spi(es with a head either cylindrical or hemispherical are used for fi$ing chairs of

3.9. Rails to wooden sleepers for fi$ing slide chairs of points and crossings. These have a

blunt end and limited use

tandard spikes

These are used for cast iron chairs only to fi$ them with timber sleepers

Elastic spikes

Actually the main disadvantage with the dog head spi(es is that due to wave motion the spi(e

comes out hence the fastening will get loose. To over come this disadvantage elastic spi(es

are introduced which will absorb the wave motion without getting loose

%o# pikes

• It is used to hold flat footed rails to a wooden sleeper.

• The shape of the top head resembles that of a dog hence the name.


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• The section of the spi(e is s/uare shaped and the bottom part is either pointed blunted

or chisel shaped.

• They are cheap and easy to install but they move out of place due to wave motion

resulting in creep.

/EW *=E

• These are tapered screws with F threads used to fasten rails with timber sleepers.

• The head is circular with a s/uare pro&ection.

• Screw spi(es have more than double the holding power of dog spi(es but they are

costly and maintenance is more difficult.

. ,riefly explain the advanta#es and disadvanta#es of any three types of &allast

Type of ballast Advantages 6isadvantages SuitabilitySand ballast • Good drainage

properties

• Cheap „

• No noise

produced „ on the

track• Good packing „

material for CI

sleepers

• Causes excessive

wear

• Blows o easily

• !oor retentivelyof packing

• Track cannot bemaintained to highstandards

• Suitable for CI

pot sleeper

tracks

• Not suitable

for high"speed

tracks

#oorum

ballast• Cheap$ if locally

available

• !revents water

from percolating

• !rovides good

aesthetics

• %ery soft and turns

into dust

• #aintenance of

track the di&cult

• 'uality of trackaverage

• (sed as a sub"

ballast

• Initial ballast

for new

construction

Coal ash or • )asy availability • *armful for steel • Normally used


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cinder• on railways

• „ %ery cheap

• „ Good drainage

• sleepers

• Corrodes rail

bottom and steel

sleepers

• Soft and easily

pulveri+ed• #aintenance is

• di&cult

in

• yards and

sidings

• Suitable for

repairs

•of formations,oods andemergencies

• Not -t for

high"speed

tracks

Broken stone

ballast• *ard and durable

when procured

from hard rocks

• Good drainage

properties

• Is stable$ and

resilient to the

track

• )conomical inthe long run

• Initial cost is high

• .i&culties in

procurement

• /ngular shape may

in0ure woodensleepers

• Suitable for

high speedtracks

+. %ra! the dimensional sketch of fish plate. $lso state the reuirements of 9ish

plate

euirements of fish plates

!. They must support the underside of the rail and top of the foot

". They should allow a free movement of rails for e$pansion and contraction for this

purpose they should not touch web of the rail

*. They must be of such a section as to bear the stresses due to lateral and vertical

bending moments without getting distorted and must absorb the shoc( caused by the

&umping of wheel over the gap

,. They should hold the end of rail both laterally in line and vertically in level

-. They should be provided against the wear of fish plate due to impact e$pansion and

contraction

. Strength should be atleast -2 to 0 (gGcm"


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0. %inimum Elongation re/uired is "5H

2. Sectional area of fish plate and rail section should be same

4. Strength should appro$imately be of --H of rail strength

. Mention the various reuirements of &allast. Mention different types of &allastused in permanent !ay

3allast material should possess the following properties.

!. It should be tough and wear resistant.

". It should be hard so that it does not get crushed under the moving loads.

*. It should be generally cubical with sharp edges.

,. It should be non1porous and should not absorb waterIt should resist both attrition and

abrasion.

-. It should be durable and should not get pulveri;ed or disintegrated under adverse

weather conditions.

. It should allow for good drainage of water.

0. It should be cheap and economical. 6ifferent types of ballast used in permanent way are as follows

!. Sand ballast

". %oorum ballast

*. oal ash or cinder

,. 3ro(en stone ballast

-. @ther types of ballast

5. Mention the reuirement of ideal sleeper

!. 9olding the rails in their correct gauge and alignment

". #iving a firm and even support to the rails

*. Transferring the load evenly from the rails to a wider area of the ballast

,. Acting as an elastic medium between the rails and the ballast to absorb the blows and

vibrations caused by moving loads

-. ?roviding longitudinal and lateral stability to the permanent way

. ?roviding the means to rectify the trac( geometry during their service life.

0. To support the rails at proper level in straight trac(s and at proper super elevation on

curves

2. The initial as well as maintenance cost should be minimum.

4. The weight of the sleeper should be moderate so that it is convenient to handle.

!5. The designs of the sleeper and the fastenings should be such that it is possible to fi$and remove the rails easily.

!!. The sleeper should have sufficient bearing area so that the ballast under it is not

crushed.

!". The sleeper should be such that it is possible to maintain and ad&ust the gauge

properly.

!*. The material of the sleeper and its design should be such that it does not brea( or get

damaged during pac(ing.

!,. The design of the sleeper should be such that it is possible to have trac( circuiting.

!-. The sleeper should be capable of resisting vibrations and shoc(s caused by the

passage of fast moving trains.

!. The sleeper should have anti1sabotage and anti1theft features.


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!0. 7ittings of the sleepers should be such that they can be easily ad&usted during

maintenance operations such as easy lifting pac(ing removal and replacement.

6. Explain the &asis for arrivin# at minimum depth of &allast section

Minimum depth of ,allast section The load on the sleeper is transferred through the medium of the ballast to theformation1 The pressure distribution in the ballast section depends upon the si+eand shape of the ballast and the degree of consolidation1 Though the lines ofe2ual pressure are in the shape of a bulb$ yet for simplicity$ the dispersion ofload can be assumed to be roughly 345 to the vertical1 In order to ensure that theload is transferred evenly on the formation$ the depth of the ballast should besuch that the dispersion lines do not overlap each other1 6or the even distributionof load on the formation$ the depth of the ballast is determined by the followingformula

Sleeper spacing 7 width of the sleeper 8 9 : depth of ballastIf a BG track is laid with wooden sleepers with a sleeper density of N 8 ;$ then the sleeper spacing would be ;9? cm of ballast below the sleeper bed is normallyprescribed on Indian @ailways

8. Explain the follo!in# 1) sleeper density 2) concrete sleeper

leeper %ensity and pacin# of leepersSleeper density is the number of sleepers per rail length. It is specified as M x or N x

where M or N is the length of the rail in metres and x is a number that varies according to

factors such as 8a: a$le load and speed 8b: type and section of rails 8c: type and strength of

the sleepers 8d: type of ballast and ballast cushion and 8e: nature of formation. If the sleeper

density is M 0 on a broad gauge route and the length of the rail is !* m it means that !* 0

D "5 sleepers will be used per rail on that route. The number of sleepers in a trac( can also be

specified by indicating the number of sleepers per (ilometre of the trac(. 7or e$ample !-,5

sleepersG(m. This specification becomes more relevant particularly in cases where rails are

welded and the length of the rail does not have much bearing on the number of sleepers

re/uired. This system of specifying the number of sleepers per (ilometre e$ists in many

foreign countries and is now being adopted by Indian Railways as well. The spacing of

sleepers is fi$ed depending upon the sleeper density. Spacing is not (ept uniform throughout


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the rail length. It is closer near the &oints because of the wea(ness of the &oints and impact of

moving loads on them. There is however a limitation to the close spacing of the sleepers as

enough space is re/uired for wor(ing the beaters that are used to pac( the &oint sleepers.

/oncrete leepers

These types of sleepers were promoted because of shortage of good wooden sleepers andneed for better design and economy of sleepers on sustainable basis.

These sleepers are mainly of two types

!. Reinforced cement concrete sleepers

". ?re1stressed concrete sleepers

E$periments have shown that concrete sleepers are idela material for sleeper for the

following reasons

!. They are made of a strong homogeneous material impervious to effect of moisture

and is unaffected by the chemical attac( of atmospheric gases or sub Jsoil salts

". It is easily moulded to si;e and shape re/uired by scientific investigation to withstandthe stresses produced by fast and heavy traffic

$dvanta#es and disadvanta#es

oncrete sleepers have the following advantages and disadvantages.

$dvanta#es

• 6urable with life range from ,51-5 years

• They can be produced on large /uantities locally by installing a plant

• 9eavier than all other types thus giving better lateral stability to the trac(

• #ood insulators and thus suitable for use in trac( circuited lines

• Efficient in controlling creep 1 They are not attac(ed by corrosion

• 7ree from attac(s of vermin and decay suitable for all types of soils

• %ost suitable for welded trac(s1 ?revent buc(ling more efficiently

• Initial cost is high but proves to be economical in long run

• Effectively and strongly hold the trac( to gauge

• Inflammable and fire resistant

%isadvanta#es

8a: 9andling and laying concrete sleepers is difficult due to their large weights.

%echanical methods which involve considerable initial e$penditure have to be adopted for

handling them.

8b: oncrete sleepers are heavily damaged at the time of derailment.

8c: oncrete sleepers have no scrap value.8d: oncrete sleepers are not suitable for beater pac(ing.

8f: oncrete sleepers should preferably be maintained by heavy Kon trac(’ tampers.

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