Railway engineering

Prepared by

M.Shanmugaraj

Lecturer / Civil

V.S.V.N Polytechnic College

Virudhunagar

UNIT-III

RAILWAY ENGINEERING

3.1 INTRODUCTION

Amongst the different modes of

transport, Railways have their greatest

utilization in the transport of large volumes

of heavy and bulk commodities and

passengers over long distances with safety,

comfort and convenience.

History of Railways

Railways were first introduced to India in 1853

from Bombay toThane

A British engineer, Robert Maitland Brereton, was

responsible for the expansion of the railways from

1857 onwards.

The Allahabad-Jabalpur branch line of the East

Indian Railway had been opened in June 1867

In 1951 the systems were nationalised as one unit,

the Indian Railways, becoming one of the largest

networks in the world.

Indian Railways is the world's ninth largest commercial or utility employer, by number of employees, with over 1.4 million employees. As for rolling stock, IR holds over 239,281 Freight Wagons, 59,713 Passenger Coaches and 9,549 Locomotives (43 steam, 5,197 diesel and 4,309 electric locomotives).

As of 31 March 2013, 23,541 km (14,628 mi) (36%) of the total 65,000 km (40,000 mi) km route length was electrified. Since 1960, almost all electrified sections on IR use 25,000 Volt AC traction through overhead catenary delivery.

Definition

Adhesion of wheels:-

Resistance offered by the friction between the metal surface of the rail and the wheel

Adzing of sleepers:-

In order to obtain an inward slope of 1 in 20 for the rail, the sleepers are cut to form a table. The process of cutting the wooden sleeper or casting the concrete sleepers accordingly is known as Adzing of sleepers.

Ash Pits:-

Long masonry pits, constructed longitudinally inside and under

the track to collect the ash from steam locomotives

Ballast:-

Granular material used in packing under and around the sleepers

to transfer load from the sleepers.

Check rails:-

The rails, which are introduced along the inner rail of a track

on sharp curves for reducing the wear of rails, are called

‘check rails’.

Check rails are also provided along the straight rails opposite

the crossings in turnouts

Check rails:-

Bearing plates:

Mild steel, or cast iron plates used for fixing the rail with

wooden sleepers.

The rectangular plates made of either mild steel, cast iron,

wrought iron, or malleable steel which are interposed

between the foot of a flat footed rail and wooden sleeper to

distribute the load on a larger area, are called bearing plates.

Bearing plates:

Bearing plates:

Chairs:-

For keeping the bull headed rail in proper position, special

devices are provided in between the sleepers and the rails

which is known as the Chairs.

Chairs :

Coning of wheel:-

"Coning of wheels" is what allows a train to take a turn

without slipping off its tracks.

Coning of wheel:-

Creep of rails:-

The longitudinal movement of rails, in a track is known as

creep of rails

Drop Pits:- Pits constructed in the loco shed for taking down wheels of

the locomotive during repair.

Examination Pits:-

Pits constructed for examination of the engines underneath

Detectors:- A defect detector is a device used on railroads to detect

axle and signal problems in passing trains. The detectors are

normally integrated into the tracks and often include sensors

to detect several different kinds of problems that could occur.

Hogged Rails:-

A Hogged Rail is the surface defect of the rail in which the

rail ends are bent downward at the joints.

Kinks:-

Lateral shift in rails due to loose joints and defective gauge is

called as Kinks

Flag Stations:-

A railroad station where trains stop only when a flag or other

signal is displayed or when passengers are to be discharged.

Fouling Mark:-

It is the point beyond the converging point of two or more

tracks before which train on one of those tracks have to be

stopped so that train movement is not obstructed in other

tracks.

Gang Hut:-

Residential quarters provided near the centre of the gauge

beat are called gang hut

Guard Rails:-

Extra rails provided over bridges to prevent damage and

derailment on the bridge

Heel:-

Tapered rail fixed to the main rails are called Heel.

Level crossing:-

Place when the road and railway line cross each other at the

same level.

Rolling stock

Rolling stock comprises all

the vehicles that move on a railway

It usually includes both powered and

unpowered vehicles, for example

locomotives, railroad cars, coaches,

and wagons

Stock rail:-

This is the main rail at the switch where the tongue rail

fits against it.

Stock rail:-

Tongue rail:-

Tapered rail used in switch

Tube railways:-

Underground railways at about 27m or more in depth below

the ground

Railroad station:

Set of installations of a railway, where passengers embark and

disembark and goods are loaded and unloaded.

Water tower:

water container.

Tunnel: underground passage.

Viaduct: railway bridge.

Bridge: Construction that allows passage between two points

separated by a depression or an obstacle.

Overpass:

Elevation of a railway over a highway so they do not

intersect.

Engine shed: Place where locomotives are

stored.

Rails

A steel bar or continuous line of bars laid on the ground as

one of a pair forming a railway track.

Sleeper

It is one of the cross braces that support the rails on a railway

track

Ballast Track ballast forms the track bed upon which railway

sleepers are laid

Gauge

Rail gauge is the distance between the inner sides of the two

parallel rails that make up a single railway line

Turn out

A complete set of points and crossings along with a lead rail

is known as turnout

Turn out

Right Hand Turn out

If a train from main track is diverted to the right of the main

route in the facing direction, then this diversion is known as

Right-hand turnouts

Left Hand Turn out

If a train from main track is diverted to the left of the main

route in the facing direction, then this diversion is known as

Left-hand turnouts.

Points and Crossing Special arrangement on railway track for enabling trains to

divert from one track to another

Yards

System of tracks for various purposes such as receiving,

storing and despatch of goods, wagons and passenger

coaches, etc.

Signals

Device by which movement of train is controlled

Rail Gauges

Rail gauge is the distance between the inner sides of the two

parallel rails that make up a single railway line

Rail gauge is the distance between two rails of a railroad.

Sixty percent of the world's railways use a 4 feet 8½ inch

(1435 mm) gauge, which is known as standard gauge or

international gauge.

Rail gauges larger than standard gauge are called broad

gauge, and rail gauges smaller than standard are called

narrow gauge.

A dual gauge railway has three or four rails positioned so

that trains of two different gauges can use it.

A place where different gauges meet is called a break of

gauge.

Rail Gauges

Types of Rail Gauges

The different gauges prevalent in India are of the

following these types :-

Broad gauge (1676),

Metre gauge (1000),

Narrow gauge (762 mm & 610 mm).

Types of Rail Gauges

1.Broad Gauge

When the clear horizontal distance between the

inner faces of two parallel rails forming a track is

1676mm the gauge is called Broad Gauge (B.G)

This gauge is also known as standard gauge of

India and is the broadest gauge of the world.

The Other countries using the Broad Gauge are

Pakistan, Bangladesh, SriLanka, Brazil,

Argentine,etc.50% India’s railway tracks have

been laid to this gauge.

Suitability :-

Broad gauge is suitable under the following

Conditions :-

(i) When sufficient funds are available for the

railway project.

(ii) When the prospects of revenue are very

bright.

This gauge is, therefore, used for tracks in plain

areas which are densely populated i.e. for routes

of maximum traffic, intensities and at places

which are centers of industry and commerce

2.Metre Gauge

When the clear horizontal distance between the

inner faces of two parallel rails forming a track is

1000mm, the gauge is known as Metre Gauge

(M.G)

The other countries using Metre gauge are

France, Switzerland, Argentine, etc. 40% of

India’s railway tracks have been laid to this gauge.

Suitability :-

Metre Gauge is suitable under the following

conditions:-

(i) When the funds available for the railway

project are inadequate.

(ii) When the prospects of revenue are not very

bright.

This gauge is, therefore, used for tracks in under-

developed areas and in interior areas

3.Narrow Gauge

When the clear horizontal distance between the

inner faces of two parallel rails forming a track is

either 762mm or 610mm, the gauge is known as

Narrow gauge (N.G)

The other countries using narrow gauge are

Britain, South Africa, etc. 10% of India’s railway

tracks have been laid to this gauge.

Suitability :-

Narrow gauge is suitable under the following conditions :-

( i) When the construction of a track with wider gauge is

prohibited due to the provision of sharp curves, steep

gradients, narrow bridges and tunnels etc.

(ii) When the prospects of revenue are not very bright.

This gauge is, therefore, used in hilly and very thinly

populated areas. The feeder gauge is commonly used for

feeding raw materials to big government manufacturing

concerns as well as to private factories such as steel plants,

oil refineries, sugar factories, etc.

Uniformity in gauges

One country should have only one gauge

throughout its various parts.

But the policy of India and its Topographical,

Geological and Financial conditions have led to

adopt various gauges in its different parts.

Advantages of Breaking the Gauge

i). The most effective advantage of breaking the gauge is to

render the railway an economical and profitable concern.

ii). It facilitates the provision of a steeper gradient, sharp

curves and narrow tunnels by adopting a less wide gauge in

hilly and rocky areas.

Disadvantages of Breaking the

Gauge :-

i). It causes much inconvenience to the passengers while

changing the train at station, with change of gauge.

ii). It causes delay in movement of people and goods.

iii). It results in wastage of time.

iv). It involves extra labour for unloading and reloading the

goods. The goods are also likely to be damaged or dislocated at

the junction station, having change of gauge.

v). It requires the provision of extra and costly transshipment

yards, godowns, sheds, etc. at every junction station having

change of gauge.

vi). It causes extreme difficulty in quick movement of military

and ammunition during war days.

Loading gauge

A loading gauge defines the maximum height and width

for railway vehicles and their loads to ensure safe passage

through bridges, tunnels and other structures.

The loading gauge determines the sizes of passenger trains

and the size of shipping containers that can be conveyed on a

section of railway line and varies across the world and often

within a single railway system.

Loading gauge

A loading gauge is the envelope or contoured shape within

which all railroad cars, locomotives, coaches, buses, trucks

and other vehicles, must fit.

It varies between different countries and may also vary on

different lines within a country. For example, metro trains

might have smaller loading gauge than conventional trains to

allow smaller tunnels.

In that case metro trains may run on conventional tracks, but

not vice versa.

Loading gauge

Loading gauge

Loading gauge

In more recent times, the term loading gauge has fallen

out of use among railway professionals, since it is a purely

static concept and ignores other factors affecting clearance.

Indian Railways 1,676 mm (5 ft 6 in) gauge track have very

large loading gauge. 3,660 mm (12 ft 0 in) wide and

5,300 mm (17 ft 5 in) high for passenger traffic.

In India 3,250 mm (10 ft 8 in) wide and 7,000 mm

(23 ft 0 in) high on the freight only lines, and 3,250 mm

(10 ft 8 in) wide and 6,150 mm (20 ft 2 in) high on the

passenger lines.

The smallest loading gauge for a railway of

the 1,676 mm (5 ft 6 in) gauge track is Delhi Metro.

Which is 3,250 mm (10 ft 8 in) wide and 4,140 mm

(13 ft 7 in) high.

Construction gauge.

By adding suitable clearance at the top side of the

loading gauge construction gauge is obtained.

It decides the dimensions such as height and

width of structures in bridges and tunnels along

the track so that all wagons may pass through

them without damage to the structures

RAILS

General

Rail is similar to steel girders. These are placed end to end to

provide continuous and level surface for the trains to move

Functions of Rail:

To provide continuous and level surface for

movement of train.

To provide a smooth pathway so that friction

between rail and wheel become less.

Serve as a lateral guide for the running of wheels.

Transferring the load into the sleeper.

To bear the stresses developed in the track due to

temperature changes and loading patterns.

To resist breaking forces caused due to stoppage

of trains.

Requirements of an ideal railThe main requirements of an ideal rail section are as under:

(1) The section of the rail should be such that the load of

eh wheels is transferred to the sleepers without

exceeding the permissible stresses.

(2) The section of the rail should be able to withstand the

lateral forces caused due to fast moving trains.

(3) The underside of the head and top of the foot of the

rail section should be of such a slope that the fishplates fit

snugly.

(4) The center of gravity of the rail section should

preferably coincide the center of the height of the rail so

that maximum tensile and compressive stresses are nearly

equal.

(5) The web of the rail section should be such that it can safely

bear the vertical load without buckling.

(6) The head of the rail should be sufficiently thick for

adequate margin of vertical wear.

(7) The foot of rail should provide sufficient bearing area on

the underlying sleepers so that the compressive stresses on the

timber sleeper remain within permissible limits.

(8) The section of the rails should be such that the ends of two

adjacent rails can be efficiently jointed with a pair of fish

plates.

(9) The surfaces for rail table and gauge face should be

sufficiently hard to resist the wear.

(10) The contact area between the rail and wheel flange should

be as large as possible to reduce the contact stresses.

(12) The composition of the steel should conform to the

specifications adopted for its manufacture by Open Hearth of

Duplex Process.

(13) The overall height of the rail should be adequate to provide

sufficient stiffness and strength as a simply supported beam.

(14) The stiffness of a rail section depends upon the moment of

inertia. The economical design should provide maximum

moment of inertia per unit weigh of rail with due regard to

other factors.

(15) The section modulii of the rail section and that of a pair of

fish plates should be adequate so as to keep the rail and fish

plates within permissible limits.

(16) The foot of the rail should be wide enough so that the rail

is stable against overturning.

Types of rail sections

1. Double headed rails

2. Bull headed rails

3. Flat footed rails

Types of rail sections

Types of rail sections

Double headed rails:

These were the rails which were used in the beginning, which

were double headed and consisting of a dumb-bell section.

The idea behind using these rails was that when the head was

worn out in course of time, the rail can be inverted and

reused.

But as time passed indentations were formed in the lower

table due to which smooth running over the surface at the top

was impossible.

Bull headed rails:

In this type of rail the head was made a little thicker and

stronger than the lower part by adding more metal to it, so

that it can withstand the stresses.

Flat footed rails: These rails are also called as vignole's rails.

Initially the flat footed rails were fixed to the sleepers

directly and no chairs and keys were required.

Later on due to heavy train loads problems arose which

lead to steel bearing plates between the sleeper and the

rail. at rail joints and other important places these are the

rails which are most commonly used in india.

Length of rails

The most common length for BG rails is 13m (42'8'')

although double-length rails (26m, 85'4'') are seen in

some places.

MG rails are usually 12m (39'4'') in length.

NG rails vary, but the commonest length is 9m (29'6'').

Much earlier (before the metric system was adopted!),

rails were generally produced in sizes of 11, 12, or 14

yards (33', 36', 42'), less commonly 13 yards (39') or 10

yards (30' - NG).

Factors governing length of rails:-

Manufacturing cost

Transportation facility

Lifting and handling operation

Welding of railsPurpose of welding:

To increase the length of the rails

To repair the worn out or damaged rails

To build up worn out points and rails on the sharp curves

Welded rail sections are of two

types:

Short Welded Rail or SWR which consists of just

two or three rails welded together, and Long

Welded Rail or LWR which covers anything

longer.

The welding of rails is carried out in a depot by

the "Flash butt welding process and at site by the

"ThermitWelding" process.

Advantages of welding rails: (1) Welding of rails increases the life of the rails due to decrease in

wear of the ends.

(2) Welded rails provide more comfort to the passengers due to

smooth running of wheels over welded joints.

(3) Welding of rails reduces the creep because frictional resistances

increase with the increase in rail length.

(4) As discontinuity of rails is reduced, the defects such as

hammering rail joints, displacement of joint, disturbance in

alignment and running surface, are also eliminated.

(5) A welded rail panel provides better track circuiting on the

electrified tracks.

(6) Welded rails provide better performance and reduce the effects

of impact on large span bridges.

(7) Long welded rail length dampens the intensity of high frequency

vibrations due to moving loads.

(8) Welding increases the life and decreases the wear of rails.

(9) By welding of rails, the cost of track construction decreases due to

elimination of a large number of rail joints.

(10) Fast and heavy traffic may be permitted on track with welded rails.

(11) The use of long welded rails, affords better longitudinal, lateral

and vertical stability to the track.

(12) In a welded rail panel, the number of joints is less. This saves the

fuel consumption as it eliminates the loss of strain and impact energy at

the rail joints.

(13) In welded rail panels, the risk of sabotage and accidents, are

considerably reduced.

(14) Welding of rails reduces the maintenance cost by about 20% to

40%.

Wear of rails Wear on head of rail

Wear on ends of rail

Wear of rail on curve

Wear on head of rail Wear on head of rail is due to abrasion on moving rails.

Due to grinding action of sand or dust between the rails and

wheels of the train.

When train starts or applies brakes, the wheel just slides on

the rails causing wear on the head.

Load coming on to a track may exceed the carrying capacity

of the section. Thus causing the wear in the head of rail.

Wear on ends of rail It is much greater than the wear on the head of the rail.

This type of the wear is resulted due to the blows which

the rail receive when the wheel jumps the space between

the rail ends.

The ends are battered by such blows.

The contact surface between the sleepers and the rail is

worn as the as the effect of these blows increased.

The ballast under the sleepers will loosen due to increase

in the intensity of vibrations, also he sleeper will

depressed due the displacement of ballast, also the fish

plates will get loose under the constant impact of

increasing vibrations

Wear on ends of rail

Wear of rail on curve On the curve the wear of the rail takes place in both inner

and outer rails.

On the curve, the outer wheel has to move through greater

distance than the inner wheel. And the inner wheel has to

slide over the inner rail.

As a result of this sliding wear of the inner rail occur because

the metal in the rail head is burnt.

Wear of rail on curve

Coning of wheels

The flanges of wheel is never made flat, but they

are in the shape of cone with a slope of 1 in 20.

(Sloping of the wheel from the vertical axis)

The coning of wheels is mainly done to maintain

the vehicle in the central position with respect to

the track.

It is done to maintain the vehicle in the central

position with respect to the track

Coning of wheels

Advantages of coning the wheels

(i) Coning the wheels reduces the depreciation of

the wheel rims and rails. Depreciation is caused

because of the friction action of rims with inner

faces of the rail top.

(ii) Coning also gives an option of lateral drift of

the hinge with is wheels.

(iii) Coning also prevents, to some extent, the

slipping of the wheels.

Hogged rails

A hogged rail is one with its end or ends bent in vertical

direction. Caused due to battering action of wheels

Causes of Hogging

Due to loose packing under the joints and loose fish

plates.

Preventing steps

Hogged rails are removed and replaced by new rails.

Deflected ends can be brought in to their original shape

and size by welding

The deflected ends of the rails are cut off and fresh holes

drilled for fixing the fish plates.

The bent or deflected ends of rails can be straightened

Bending of rails

On curves the rail is bent true to the curvature

of the curve. In flat curves less than 30 the rails

need no bending as they are retained in curve

position by the sleepers.

With curves more than 30 it is desirable to

bend the rails before fixing them with sleepers.

Bending of rails

Creep of rails

It is defined as the longitudinal movement of rails with

respect to sleepers in a track.

Causes of creep:

Wave motion of trains.

Expansion and contraction of rails due to variation in

temperature.

Due to starting, accelerating, slowing down (decelerating)

and stopping of trains.

Rail deflection under the moving loads from the wheels

Heavy traffic in one direction

Greater on curves

Old rails have more creep

More with steep gradient

Poor maintenance of track

Effects of Creep:

Expansion gap is reduced, buckling of track take

place.

Sleepers are moved out of a square.

Crossing points get disturbed.

Rail joints are opened, stresses are set up in fish

plates and bolts.

Movement of switches is made difficult

Smashing of fish plate, bolts, bending of bars,

kinks at joints

Prevention of creep:

Pulling back the rails

Provision of Anchors

Use of steel sleepers

Efficient and proper maintenance

SLEEPERS AND BALLAST

Definition:

Sleepers are used as a base for laying railway tracks. Sleepers

were traditionally made from wood but are now usually

made from concrete.

Ties are laid on top of sand, gravel or heavy crushed stone -

called ballast.

SLEEPERS AND BALLAST

SLEEPERS AND BALLAST

Functions of Sleepers In a railway track, sleepers perform the following functions:

(1) To hold the rails t proper gauge in all situations. i.e. exact gauge

along straights and flat curves, slightly loose on sharp curves and

slightly tight in diamond crossings.

(2) To support the rails firmly and evenly throughout.

(3) To distribute the load transmitted through rails over large area of

ballast underneath or to the bridge girders as the case may be.

(4) To hold the rails to proper level in turnouts and crossovers, and

at 1 in 20 in ward slope along straight tracks.

(5) To provide and elastic medium between the rails and ballast and

also to absorb the vibrations caused due to moving axle loads.

(6) To maintain proper alignment of the track. On curves proper

cant is provided by raising the outer rail and tamping he required

quantity of ballast bellow th rails.

(7) To provide the general stability of the permanent

way throughout.

(8) To provide the insulation of track for the

electrified for signaling.

(9) To provide easy replacement of the rail fastenings

without any serious traffic disturbances

(10) Holding rails to correct gauge and alignment.

(11) Firm and even support to rails.

(12) Transferring the load evenly from rails to wider

area of ballast.

(13) Elastic medium between rails and ballast.

(14) Providing longitudinal and lateral stability

Requirements of a good Sleeper A good sleeper should meet the following requirements:

(1) The initial cost and the maintenance cost of the sleepers

should be low.

(2) The fittings required for fixing the rails on to the sleepers,

should be simple which can be easily adjusted during the

maintenance.

(3) The crushing strength of the sleepers should be more with

moderate weight.

(4) They should be able to maintain a perfect alignment, gauge

and levels of the rails and should afford efficient adjustment and

maintenance.

(5) They should provide sufficient bearing area to hold the rail

seats and for the ballast to be supported on, to resist the crushing

due to movement of heavy axle loads.

(6) The sleeper spacing should be such as t remove and

replace the ballast during regular maintenance operation.

(7) They should be capable to resist the shocks and

vibrations caused due to fast moving vehicles at high

speeds.

(8) They should provide insulation facilities for track

circuiting in the electrified sections.

(9) The sleepers should be strong enough to withstand the

pressure during packing process.

(10) The sleepers should be of such a design that they

remain in their positions and do not get disturbed due t

moving trains.

(11) The material used for the sleeper be such that it does

not attract the sabotage and the theft qualities.

Types of Sleepers

Sleepers based on the materials

Timber sleepers

Steel sleepers

Cast iron sleepers

R.C.C sleepers

Pre-stressed concrete sleepers.

Sleepers depending on the location

Longitudinal sleepers

Transverse sleepers

Longitudinal sleepers

These are earlier form of sleepers which are not

in use nowadays.

It consists of slabs or pieces of timber placed

parallel to the rails.

To maintain the correct gauge cross pieces were

provided.

These sleepers were costly

Noise created by the track is considerable

Longitudinal sleepers

Transverse sleepers

Also knows as cross sleepers.

Placed at right angles under the rails.

Eliminated the inconvenience of

longitudinal sleepers

Transverse sleepers

Timber sleepers (Wooden sleepers)

Ideal type and universally used they are two categories of

hard wood sleepers such as Sal, Teak, Kongu etc., and soft

vwood sleepers such as deodar, chir, treated timbers are use

in this categories.

Timber sleepers (Wooden sleepers)

Advantages of Wooden Sleepers:

(1) They have proved very useful for heavy loads and high-

speed trains.

(2) They are cheap and easy to manufacture.

(3) They can be handled easily without any damage.

(4) They maintain the correct alignment.

(5) They are most suitable for track circuiting.

(6) They can be used with or without ballast.

(7) They can be used for gauntlet tracks.

(8) They are suitable in the areas having yielding

formations.

Disadvantages of Wooden Sleepers: They are easily subjected to wear and decay due to various

factors, i.e. vermin, white ants, rail-cutting, warping, etc. Hence,

these have a short life.

(1) They do not maintain the gauge accurately.

(2) They easily develop cracks with beater packing.

(3) They require the highest maintenance cost as compared to

other types of sleepers.

(4) They get easily disturbed from their positions under heavy

loads.

(5) They need special treatment for fire protection.

(6) Their scrap value is low.

(7) They are not suitable for modern LWR track because of their

lighter weight.

Description of Wooden Sleepers

Size of wooden sleepers in mm : B.G. : For

ordinary track 2750x250x130 (9ᾼx10῀x5῀)

Life of Sleeper: Durable 19 years (B.G.)/ 31

years (M.G.)

Steel sleepers They are in the form of steel trough on which rails are fixed

by keys or nuts or bolts

Advantages of steel Sleepers

The steel sleepers possess the following advantages:

(1) They are manufactured by a simple operation.

(2) They can be easily handled as theses are light in

weight as compared to other types of sleepers. Hence,

damages during handling and transporting are less.

(3) Less number of fastenings are required and that too

simple in nature.

(4) The maintenance and adjustment of gauge are easy as

compared to the other of sleepers.

(5) These sleepers are rolled sections in one piece.

(6) Their life is longer than that of other types of

sleepers.

(7) They provide better lateral rigidity to the track.

(8) They are not attacked by vermin’s.

(9) They are not susceptible to fire hazards.

(10) Their scrap value is good.

Disadvantages of Steel of Sleepers

The steel sleepers possess the following disadvantages:

(1) They get easily rusted and corroded.

(2) They develop cracks at rail seats or near lugs.

(3) Their lugs get broken easily.

(4) The steel sleepers do not provide effective track circuiting

(5) The steel sleepers can only be for the type of rails for

which theses are manufactured.

(6) These develop the tendency to become center bound

because of slope at both ends.

(7) The overall cost of steel sleepers is more than that of

timber sleepers.

Cast iron sleepers

Sleepers made of cast iron are called cast iron sleepers

Type of Cast Iron Sleepers :

A) C. I. Pot Sleepers

B) C S T- 9 Sleepers

Cast Iron Pot type sleepers

Consists of two hollow pots of circular or elliptical shape

placed inverted on the ballast section.

Two pots are connected by the tie bars of section 5cm X

1.25cm,

Each pot has two hoes for ballast packing and inspection, the

rail is placed on the top of the pot in a rail seat

Cast Iron Pot type sleepers

Cast Iron Plate type sleepers

Consist of rectangular plates of size about 86cm X 30.5cm,

with projecting ribs under the plates for their lateral stability.

The tie bars can be fixed to the plate keys, gibs, cotter keys

and distance piece etc.

It also provide an effective bearing area on BG

Cast Iron Plate type sleepers

Advantages of Cast Iron Sleepers

• Long life upto 50-60 years

• High scrape value as they can be remolded

• Can be manufactured locally

• Provided sufficient bearing area

• Much stronger at the rail seat

• Prevent and check creep of rail

• They are not attacked by vermin

Disadvantages Cast Iron Sleepers

• They are prone to corrosion and cannot be used in salty

formations and coastal areas

• Not suitable for track circuited portions of railways

• Can badly damage under derailment

• Difficult to maintain the gauge as the two pots are

independent

• Require a large number of fastening materials

• Difficult to handle and may be easily damaged

• Lack of good shock absorber

• They are expensive

Concrete sleepers

R.C.C and pre-stressed concrete sleepers are now replacing

all other types of sleepers except to some special

circumstances such as crossing bridges etc here timber

sleepers are used.

They were first of all used in France round about in 1914 but

are common since 1950.

They may be a twin block sleepers joined by an angle iron.

It may be a single block pre-stressed type.

Concrete sleepers are much heavier than wooden ones, so

they resist movement better.

Concrete sleepers

Advantages Concrete Sleepers • Durable with life range from 40-50 years

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

• Heavier than all other types thus giving better lateral stability to the

track

• Good insulators and thus suitable for use in track circuited lines

• Efficient in controlling creep

• They are not attacked by corrosion

• Free from attacks of vermin and decay, suitable for all types of soils

• Most suitable for welded tracks

• Prevent buckling more efficiently

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

• Effectively and strongly hold the track to gauge

• Inflammable and fire resistant

Disadvantages Concrete Sleepers

• Difficult to be handled

• Difficult to be manufactured in different sizes thus

cannot be used in bridges and crossing

• Can be damaged easily while loading and unloading

Pre-stressed concrete sleepers.

The concrete is put under a very high initial compression.

All the disadvantages of RC sleepers have been eliminated by

pre stressing sleepers

Two types of pre stressed sleepers (i) Pre-tensioned sleeper

(ii) Post tensioned sleeper

Pre-stressed concrete sleepers.

Sleeper Density Sleeper density= Number of sleepers per unit rail length (per

unit track length for welded rail)

Number of sleepers per rail varies from N+3 to N+6 for main

tracks, N-Length of the rail

Minimum Density

MKS: Minimum sleeper density= M+7 (BG)

FPS: Minimum sleeper density= N+3 (MG)

Factors affecting spacing/density

Axle load and speed

Type and section of rails

Type and strength of sleepers

Type of ballast and ballast cushion

Nature of formation

Ballast It is a layer of broken stones, gravel or any other such gritty

material laid and packed below and around sleepers.

The material used as an elastic cushion between the sleeper

and the top of the formation, is called ‘Ballast’

Requirements of Good Ballast Ideal ballast should possess the following characteristics:

(1) It should resist crushing under dynamic loads.

(2) The designed depth of the ballast should be able to distribute

the weight of passing trains on the formation underneath

uniformly.

(3) It should not make the track dusty due to powder formation

under dynamic wheel loads.

(4) It should be reasonably elastic.

(5) It should have resistance to abrasion and weathering

(6) It should be non-porous to provide durability to the ballast.

(7) It should hold the sleepers laterally and longitudinally under

all conditions traffic, especially on the curves.

(8) It should be able to facilitate easy drainage to rain water

Functions of Ballast The main functions of ballast of a railway track are as under:

(1) It provides a hard and level bed for the sleepers.

(2) It holds the sleepers in proper position during the passage

of moving trains.

(3) It provides to some extent an elastic bed for the track.

(4) It transmits and distributes the moving load of the trains

from the sleepers to the formation uniformly.

(5) It protects the formation surface from direct exposure to

sun, rain and frost.

(6) It provides a proper drainage to the track, keeping the

sleepers in dry condition.

Functions of Ballast

(7) It obstructs the growth of vegetations at the track

formation.

(8) It provides proper super elevation to the outer rail on

curves.

(9) It provides an easy means for correcting the unevenness

of the track.

(10) It provides the lateral and longitudinal stability to the

track

(11) It protects the sleepers from capillary moisture of

formation.

(12) It provides a media for absorption of all impacts caused

by rolling stock.

Types of Ballast

Keeping in vies the availability, workability, durability

and strength of the ballast different materials have been

used as ballast. The most important types of ballast

materials used in.

(1) Broken stones (2) Gravels (3) Sand (4)Moorum (5)

Cinder (or ash) (6) Brick bats

(7) Kankar (8) Ballast earth.

(1) Broken stone: Best material for railway track.

Due to high interlocking action it holds the track to the

correct alignment and gradient

Granite, Quartzite, hard stones, lime stones are some of the

varieties of stones

(2) Gravel: Obtained from river beds or pits

Cheaper than broken stone

Has excellent drainage property

Requires screening before use

(3) Ashes and Cinder: Residue obtained from coal used in locomotives is cinder

Has good drainage property

Corrosive property

Should not be used where steel sleepers are used

(4) Sand: Best materials for ballast

Good drainage property

Gives silent track

Good for packing of cast iron pot sleepers

(5) Moorum: Decomposed laterite rocks

Red in colour

Under heavy loads crumbles to powder

Used in sidings and embankments

(6) Kankar: Found in the form of nodules of varying size

Useful for metre gauge and narrow gauge tracks with light

traffic

(7) Brick ballast: Over burnt bricks are broken in to small pieces, used as

ballast

Fairly good enough drainage property

Becomes powder under heavy traffic and tracks become

dusty.

(8) Selected earth:

Good quality earth can be used for newly laid tracks and

sidings

RAIL FASTENINGS AND PLATE

LAYING

Rail joints

Rail joints are necessary to hold the adjoining ends of the

rails in the correct position, both in the horizontal and

vertical planes

Weakest part of the track

In order to Provide expansion and contraction due to

variation in temperature, certain gap is provided at each

joint.

This gap causes a break in continuity of rails in horizontal

as well as in vertical plane, forming the weakest point of

the track.

RAIL FASTENINGS

Types of Rail Joints

According to Position of joints

(i)Square joints (ii) Staggered joints

According to position of sleepers

(i) Suspended joints(ii) Supported joints (iii)

Bridge joints (iv) Insulated joint (v) Compromise

joint

According to Position of joints

Square Joints:

Joint in one rail is exactly opposite to the joint in the other

parallel rail is called as Square Joint

Common in straight tracks

Staggered Joints:

Joint in one rail is exactly opposite to the centre of the other

parallel rail is called as Square Joint

In India this type of joint is used in curves

It gives smoother running to the track.

According to Position of joints

According to position of sleepers(i) Suspended joints:

The rail joint when placed at the centre of two consecutive

sleepers is known as suspended joints

The load is evenly distributed on two sleepers.

When joint is depressed both rails are pressed down evenly

(ii) Supported joints:

When the sleeper is placed exactly below the rail joint, it is

known as supported joint.

Do not give sufficient support with heavy axle loads

(iii) Bridge joints: Similar to suspended joint, but a metal serving as a bridge to

connect the ends of two rails

The bridge is placed at the bottom of rails and it rests on

two sleepers

Rail fastenings: A rail fastening system is a means of fixing rails to railroad

ties.

The terms rail anchors, tie plates, chairs and track fasteners

are used to refer to parts or all of a rail fastening system.

Various types of fastening have been used over the years.

Rail fastenings:

Fish Plates:

Fish Plates:

A fishplate, splice bar or joint bar is a metal bar that is

bolted to the ends of two rails to join them together in

a track

The top and bottom edges are tapered inwards so the

device wedges itself between the top and bottom of the

rail when it is bolted into place.

In rail transport modelling, a fishplate is often a small

copper or nickel silver plate that slips onto both rails to

provide the functions of maintaining alignment and

electrical continuity

Fish bolts:

Fish Bolts:

Made up of medium or high carbon steel.

Fish bolts have to undergo shear due to heavy

transverse stresses.

Length depends on the type of fishplate used

For 44.70Kg rail, a bolt of 2.5cm dia and 12.7cm

length is used

These bolts get loose by the traffic variations and

require tightening from time to time

Spikes:

A rail spike (also known as a cut

spike or crampon) is a large nail with an offset

head that is used to secure rails and base plates

to railroad ties in the track.

Spikes:

Chairs and Keys: Chairs are required to hold bull headed rails and double headed rails in

position

Made of cast iron and help in distributing the load from the rails to thee sleepers

It consists of two jaws and a rail seat.

The web of the rail is held tightly against

the inner jaws of the chair and a key is

driven between the rail and the outer jaw

of the chair

The chair are fixed with the sleepers by

means of spikes

The shapes of chairs depend upon the type

of rails used.

Chairs and Keys:

Keys:

They are wedge-shaped wooden or metal pieces.

They keep the rail in proper position

Wooden keys are cheaper but liable to be

attacked by vermin’s, the initial cost of metal key

is more but their life is ten to 15 times more than

wooden keys.

Bearing plates:

Rectangular plates made up of mild steel or cast iron

Used below flat footed rails to distribute the load on a larger area

Prevents damage of the sleepers due to rubbing action

Holds the spike firmly to the sleepers

Bearing plates:

Bearing plates:

Blocks:

To hold the check rail at the required

distance, small blocks of steel are inserted in

between two rails

These blocks may touch either the webs or

the fishing faces or both

Blocks:

Elastic fastenings:

A rail fastening system is a means of

fixing rails to railroad ties

The conventional rigid fastenings are

not able to meet the higher stresses.

Therefore elastic fastenings are used

This may protest against the shocks,

vibrations

Elastic fastenings:

Elastic fastenings:

Elastic fastenings:

Requirements of Elastic fastenings:

It should have sufficient elasticity

It should provide longitudinal and lateral rigidity to the track

It should be able to use all types of sleepers

It should be durable

It should be easy to insert and remove

Anchors and anti-creepers:

Creep can be checked by using Anchor and Anti-creepers.

Anchors are fastenings which are fixed to the sleepers at foot of rails

Anchors are fixed at come required intervals in the rails

They depend up on the traffic, curves points, crossings

Anchors and anti-creepers:

Anchors and anti-creepers:

Anchors and anti-creepers:

Plate laying:

The operation of laying out and connecting

sleepers and connecting rail and sleepers is

known as Plate laying

The point of commencement of the new track

to be laid is the existing rail head

In new track sleepers are laid directly over the

formation, after compaction the track is then

lifted and ballast is packed around the sleeper

Methods of plate laying:

Tram line method or side method

Telescopic method

American method

Tram line method or side method:

This method is used for plate laying in flat country

Used when new track is laid nest to the existing track

For plate laying of new track, either of the following two methods may be adopted

(i)A service road is constructed parallel to the proposed track and the materials are transported to the site of the work

Tram line method or side method:

(ii)A temporary rail line parallel to the proposed

track and the materials are transported in

wagons. This temporary line is known as tram

line

In this method all the materials are taken from

the central depot in material trains on the

existing track and are spread on the formation of

new track

After completing spreading, the work of

assembling is started from one end manually

Telescopic method:

This method is used very widely in India

A large central depot is constructed near the

junction of the existing railway or highway and

the proposed railway line

The manual force is divided in to (i)Material gang

(ii)Linking-in-gangs (iii)Packing-in-gangs

(i) Material gangs:

These gangs unload the materials from the

trains

They carry the materials to the rail head and

supply them to the linking-in-gangs.

These gangs distribute sleepers, rails,

fishplates, bolts etc. to the required places

(ii) Linking-in-gangs:

These gangs mark the centre line of the proposed track and place the sleepers at required place

Rails are placed on the sleepers

Successive rails are joined together by fishplates, bolts with expansion joints

After joining the rails are fixed to the sleepers

(iii) Packing-in-gangs:

These gangs correct the rails to the

required level and gradients by packing

earth or ballast below and around the

sleepers

American method

This method involves all mechanical work

This method consists of fixing rails to the sleepers

and lifting the whole unit by heavy cranes.

First one is linked with the rail head, then the

train moves ahead by one rail length and the same

procedure is repeated.

This method is un-economical one and is not used

in India

Plasser Quick Relaying System (PQRS

method)

This is a mechanical method of laying railway track in Indian

Railways

This method is used for relaying existing track under traffic

condition without interrupting the flow of traffic

Following equipments are used for PQRS method of plate

laying

(i)Sleeper layer (ii)5 tonne portal crane (iii)Track jacks

(iv)Hand gantries (v)Engine (vi)B.F.R (open wagon for

carrying long rails) (vii)B.F.R for carrying sleeper

(viii)B.F.R for old materials

Plasser Quick Relaying System (PQRS

method)

Auxiliary track

An auxiliary track is laid with a gauge length of 3.4m.

This is to carry the required equipments and materials for laying new work.

The auxiliary track is laid over wooden blocks on cast iron posts at two metres interval.

The level of auxiliary track is laid with the same level of track.

The portal crane moves on the auxiliary track and it is used to lift and carry the rail panels.

Sleepers layers is a machine which is used for laying sleepers with required spacing and alignment

The jacks are used to support the track laying at uniform level. Hand gantries are used for moving the rails in longitudinal direction at lifted position.

Method of relaying:

Work of relaying the track is normally divided

into the following stages:

(i)Preliminary work:

To prepare schedule of materials per 100m length

or per km of the track.

The entire quantity is collected at the central

store, from which day to day requirements is

drawn

(ii)Laying of the track:

Removal of the fittings.

Removal of rails and sleepers

Placing of new sleepers

Laying of rails

Laying of second rail

Finishing

(iii)Construction of the track:

Tightening of the fittings

Distribution of ballast

Further packing of ballast

Return of released material to store

MAINTENANCE OF TRACK

Necessity of Maintenance of track:

Increases the life of track

Provides comfortable ride to the passenger

Provides safety to goods

Increase the life of rolling stock

Operating cost is reduced

Safety to passengers

Maintenance of track:

The railway track requires proper watch and

ward for security reasons

Maintenance of railway track consists of

(i) Daily maintenance (ii) Periodic Maintenance

For daily maintenance the track is divided in

to sections of 5 to 8 kms lengths.

Each section is look after by a gang

The daily maintenance consists of

General inspection of the track

Checking up of all fastenings and fittings

Tightening of bolts wherever required

Reporting by unusual occurrence

The periodic maintenance consists of detailed inspection of

the track to detect defects in the track which may not be detected

during daily maintenance.

The various aspects of periodic maintenance are as below

Maintenance of track alignment

Maintenance of track drainage

Maintenance of track components

Maintenance of level crossing

Maintenance of track materials:

The top surface of the rails should be kept at the same level

Ballast under sleepers should be regularly packed

Defective sleepers should be replaced immediately

Worn-out rails should be replaced

Kink or fracture rails should be replaced

Fastening should be tightened and oiled

Gauge should be checked and corrected

Ensure that both the rails are at same level

Maintain track drainage properly

Oiling and greasing of fishplates regularly

Flanges and check rails should be kept free from dust

Maintenance of Bridges:

Proper embankment should be provided near the

bridge

Avoid scouring near abutments and piers

Flood control measures should be taken near the

bridges

Riveted joints should be inspected periodically

Bed blocks should be checked regularly

Steel bridges should be painted regularly

Bearings of the girders should be oiled regularly

Masonry works should be inspected regularly

Maintenance of rolling stock:

Lubrication of all reciprocating parts and bearings

Wornout parts should be replaced the rolling stock

It is necessary to clean the different parts every day

All axles which have run 3,22,000Km should be

replaced

A passenger vehicle used for 30years should be

dismantled and re-assembled

The locomotive boilers have to be carefully

maintained and removed every 15 years