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RAILWAY ENGINEERING
Railway engineering is a multi-faceted engineering discipline dealing with the design,
construction and operation of all types of rail transport systems.
Economical aspects:

 Due to railways, the industrial development in for off places is possible, increasing the
land values & standard of living of the people.
 Mobility of labor has contributed to industrial development.
 During famines, railways have played the vital role in transporting food & clothing to the
affected areas.
 Commercial farming is very much helped by the railway network throughout the country.
 Speed movement of the commodities is possible through railways.

Cultural & Social aspects:

 Railway has made it easier to reach places of religious importance.
 Railway provides a convenient & safe mode of transport through out the country.
 During travel as people of different caste & religions sit together the interaction is
developed.

Political aspects:
 Railways have helped in the mass migration of the population.
 Railways have created the sense of unity among the people of different religions,
areas, castes & traditions.
 With adequate network of railways, the central administration has become easy &
effective.
PERMANTENT WAY

Definition: A permanent way or a railway track can be defined as the combination of rails,
fitted on sleepers and resting on ballast and sub grade.

Components of a Railway Track:

The Typical components are:
1. Rails
2. Sleepers (or ties)
3. Fasteners
4. Ballast (or slab track) 5. Subgrade

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The rails are joined in series by fish plates and bolts & they are fixed to sleepers by different
types of fastenings. The sleepers properly spaced, resting on ballast are suitably packed and
boxed with ballast. The layer of ballast rests on the prepared sub grade is called as the
formation.

The rails transmit the wheel load to the sleepers. The

sleepers hold the rails in proper position and transmit
the load from rails to ballast. The ballast distributes the
load over the formation and holds the sleepers in
position.
On curved tracks, super elevation is maintained by
ballast and the formation is leveled. Minimum ballast cushion is maintained at inner rail,
while the outer rail gets kept more ballast cushion. Additional quantity of ballast is provided
on the outer cess of each track for which the base width of the ballast is kept more than for a
straight track.

Requirements of an ideal permanent way:

 The gauge should be uniform and correct.

 Both the rails should be at the same level in a straight track.
 On curves proper super elevation should be provided to the outer rail.
 The permanent way should be properly designed so that the load of the train is
uniformly distributed over the two rails.
 The track should have enough lateral strength.
 The radii and super elevation, provided on curves, should be properly
designed.
 The track must have certain amount of elasticity
 All joints, points and crossings should be properly designed.
 Drainage system of permanent way should be perfect.
 All the components of permanent way should satisfy the design requirements.
 It should have adequate provision for easy renewals and repairs.

GAUGE:

The clear minimum horizontal distance between the inner (running) faces of the two rails
forming a track is known as Gauge.

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Various Gauges in Indian Railways:

Name of Gauge Width (m)
Broad gauge (BG) 1.676
Meter gauge (MG) 1.00
Narrow gauge (NG) 0.762 0.61

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. 50% India‘s railway
tracks have been laid to this gauge.
2. Meter Gauge: - When the clear horizontal distance between the inner faces of two parallel
rails forming a track is 1000mm, the gauge is known as Meter Gauge (M.G). 40% of India‘s
railway tracks have been laid to this gauge.

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) .10% of India‘s railway tracks have been laid to this gauge.

Choice of Gauge:
1. Cost considerations
2. Traffic considerations
3. Physical features of the country
4. Uniformity of gauge

1. RAILS
Definition: Rails are the members of the track laid in two parallel lines to provide an
unchanging, continuous, and level surface for the movement of trains. To be able to
withstand stresses, they are made of high-carbon steel.

Functions of Rails:
Rails are similar to steel girders. They perform the following functions in a track:

 Rails provide a continuous and level surface for the movement of trains.
 They provide a pathway which is smooth and has very little friction. The friction
between the steel wheel and the steel rail is about one-fifth of the friction between the
pneumatic tyre and a metaled road.
 They serve as a lateral guide for the wheels.
 They bear the stresses developed due to vertical loads transmitted to them through
axles and wheels of rolling stock as well as due to braking and thermal forces.
 They carry out the function of transmitting the load to a large area of the formation
through sleepers and the ballast.

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Types of Rails:
The rails used in the construction of railway track are of following types:
1. Double headed rails
2. Bull headed rails
3. Flat footed rails

Length of rail:
The longer is the rail, the lesser would be the number of joints and fittings required and the
lesser the cost of construction and maintenance. Longer rails are economical and provide
smooth and comfortable rides.

Indian Railways has standardized a rail length of 13 m (previously 42 ft.) for broad gauge
and 12 m (previously 39 ft.) for MG and NG tracks

Rail Joints
Definition: A rail joint is an integral part of the railway track as it holds together the
adjoining ends of rails in correct position, both in horizontal and vertical planes.

Requirements of an ideal rail joint:

An ideal rail joint provides the same strength and stiffness as the parent rail. The
characteristics of an ideal rail joint are briefly summarized here.

 Holding the rail ends: An ideal rail joint should hold both the rail ends in their
precise location in the horizontal as well as the vertical planes to provide as much
continuity in the track as possible. This helps in avoiding wheel jumping or the
deviation of the wheel from its normal path of movement.
 Strength: An ideal rail joint should have the same strength and stiffness as the parent
rails it joins.
 Expansion gap: The joint should provide an adequate expansion gap for the free
expansion and contraction of rails caused by changes in temperature
 Flexibility: It should provide flexibility for the easy replacement of rails, whenever
required.
 Provision for wear: It should provide for the wear of the rail ends, which is likely to

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occur under normal operating conditions.

 Elasticity: It should provide adequate elasticity as well as resistance to longitudinal
forces so as to ensure a trouble-free track.
 Cost: The initial as well as maintenance costs of an ideal rail joint should be minimal.

Types of Rail Joints:

The nomenclature of rail joints depends upon the position of the sleepers or the joints.

Classification According to Position of Sleepers:

Three types of rail joints come under this category.

i. Supported Joints
ii. Suspended Joints
iii. Bridge Joints

Supported joint: In this type of joint, the ends of the rails are supported directly on a sleeper
called as ‘joint sleeper’.

Suspended joint: In this type of joint, the ends of the rails are suspended between two
sleepers and some portion of the rail is cantilevered at the joint.

Bridge joints: The bridge joint is similar to the suspended joint except that the two sleepers
on either side of a bridge joint are connected by means of a metal flat or a corrugated plate
known as a bridge plate. This type of joint is generally not used on Indian Railways.

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Classification Based on the Position of the Joint:

Two types of rail joints fall in this category.

i. Square Joints
ii. Staggered Joints

Square joint: In this case, the joints in one rail are exactly opposite to the joints in the other
rail. This type of joint is most common on Indian Railways.

Staggered joint: In this case, the joints in one rail are somewhat staggered and are not
opposite the joints in the other rail. Staggered joints are normally preferred on curved tracks
because they hinder the centrifugal force that pushes the track outward

Creep of Rails
Definition: Creep of rails can be defined as the longitudinal movement of rails with respect
to sleepers in a track. Rails have a tendency to gradually move in the direction of dominant
traffic. Creep is common to all railway tracks, but its magnitude varies considerably from
place to place; the rail may move by several centimeters in a month at few places, while at
other locations the movement may be almost negligible.

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Theories for the development of creep:

1. Wave Motion Theory
2. Percussion Theory
3. Drag Theory

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

 Ironing effect of the wheel: 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.
 Starting and stopping operations: when a train starts or accelerates, the backward
thrust of its wheels tends to push the rail backwards. Similarly, when the train slows
down or comes to a halt, the effect of the applied brakes tends to push the rail
forward. This in turn causes creep in one direction or the other
 Changes in temperature: Creep can also develop due to variations in temperature
resulting in the expansion and contraction of the rail. Creep occurs frequently during
hot weather conditions.
 Unbalanced traffic: In a double-line section, trains move only in one direction, i.e.,
each track is unidirectional. Creep, therefore, develops in the direction of traffic. In a
single-line section, even though traffic moves in both directions, the volume of traffic
in each direction is normally variable. Creep, therefore, develops in the direction of
predominant traffic.
 Poor maintenance of track: Some minor factors, mostly relating to poor
maintenance of the track, also contribute to the development of creep. These are as
follows:

1. Improper securing of rails to sleepers

2. Limited quantities of ballast resulting in inadequate ballast resistance to the
movement of sleepers
3. Improper expansion gaps
4. Badly maintained rail joints
5. Rail seat wear in metal sleeper track
6. Rails too light for the traffic carried on them
7. Yielding formations that result in uneven cross levels
8. Other miscellaneous factors such as lack of drainage, and loose packing, uneven
spacing of sleepers

Prevention of Creep:
The remedies of creep are as follows:
1. Pulling back the rails

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2. Provision of anchors or anti creepers

3. Use of steel sleepers

2. SLEEPERS
Definition: Sleepers are transverse members of the track placed below the rails to support
and fix them in position.

Requirements of good sleepers:

 The sleepers should be sufficiently strong to act as a beam under loads.

 The sleepers should be economical.
 They should maintain correct gauge
 They should provide sufficient bearing area for the rail.
 The sleepers should have sufficient weight for stability.
 Sleepers should facilitate easy fixing and taking out of rails without disturbing them.
 They should facilitate easy removal and replacement of ballast.
 They should not be pushed out easily of their position in any direction under
maximum forces of the moving trains.
 They should be able to resist impact and vibrations of moving trains.
 They should be suitable to each type of ballast.

Types of Sleepers:
1. Wooden sleepers.
2. Steel sleepers.
3. Cast iron sleepers.
4. R.C.C. sleepers.
5. Pre stressed concrete sleepers.

3. BALLAST
Definition: Ballast is a layer of broken stones, gravel, rnoorum, or any other granular
material placed and packed below and around sleepers for distributing load from the sleepers
to the formation. It provides drainage as well as longitudinal and lateral stability to the track.

Functions of Ballast:

 It provides a level and hard bed for the sleepers to rest on.
 It holds the sleepers in position during the passage of trains.

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 It transfers and distributes load from the sleepers to a large area of the formation.
 It provides elasticity and resilience to the track for proper riding comfort.
 It provides the necessary resistance to the track for longitudinal and lateral stability.
 It provides effective drainage to the track.
 It provides an effective means of maintaining the level and alignment of the track.

Types of Ballast:
In India, the following materials are used as ballast.

1. Broken stone 2. Gravel 3. Sand 4. Ashes or

Cinders
5. Kankar 6. Moorum 7. Blast furnace slag 8. Brick ballast
9. Selected earth

4. RAIL FIXTURES AND FASTENINGS

Definition: Fixtures and fastenings are fittings required for joining of rails end to end and
also for fixing the rails to sleepers in a track.

Functions of Rail Fixtures and Fastenings:

 To join the rails end to end to form full length of track.

 To fix the rails to sleepers.
 To maintain the correct alignment of the track.
 To provide proper expansion gap between rails.
 To maintain the required tilt of rails.
 To set the points and crossings in proper position.

Types of Fixtures and Fastenings:

Rail Fixtures and fastenings commonly used in a permanent way are of following types:

1. Fish plates
2. Bearing plates
3. Spikes
4. Chairs
5. Bolts
6. Keys
7. Anti-creepers

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GEOMETRIC DESIGN OF RAILWAY

Introduction: Geometric design of a railway track discusses all those parameters which
affect the geometry of the track. These parameters are as follows:
1. Gradients in the track
2. Curvature of the track: radius or degree of the curve, cant or super elevation on curves
3. Alignment of the track

Necessity of Geometric Design:

The need for proper geometric design of a track arises because of the following
considerations:

 To ensure the smooth and safe running of trains

 To achieve maximum speeds
 To carry heavy axle loads
 To avoid accidents and derailments due to a defective permanent way
 To ensure that the track requires least maintenance
 For good aesthetics

Gradients:
Gradient is the departure of the track from the original level. In an upward or rising gradient,
the track rises in the direction of movement of traffic, whereas in a falling or downward
gradient, the track falls in the direction of the movement.

Purpose of providing gradient:

 To provide a uniform rate of rise or fall to the track.

 To reduce the cost of earthwork.
 To reach different stations at different elevations etc.

Types of gradient

1. Ruling gradient
2. Momentum gradient
3. Pusher or helper gradient
4. The gradient at station yards

Ruling Gradient: The ruling gradient is the maximum gradient to which the track may be
laid in a particular section. It depends on the load of the train and additional power of the
locomotive. The ruling gradients adopted:

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1. In plains – 1 in 150 to 1 in 200

2. In Hilly tracks – 1 in 100 to 1 in 150

Momentum Gradient: Gradient which is steeper than ruling gradient and where the
advantage of momentum is utilized is known as momentum gradient. A train gets momentum
when moving in downgradient and this momentum can be utilized for up gradient. A train
while coming down a gradient gains sufficient momentum. This momentum gives additional
kinetic energy to the moving train which would help the train to rise a steeper gradient than
the ruling gradient for a certain length of the track. This rising gradient is called momentum
gradient. In such gradients, no signals are provided to stop the train.

Pusher Gradient: Pusher gradient is the gradient where an extra engine is required to push
the train. These are steeper gradient than ruling gradient and are provided at certain places of
mountains to avoid heavy cutting or to reduce the length of the track. A pusher gradient of 1
in 37 on Western Ghats with B.G. track is provided. On Darjeeling Railway with N.G. track,
a ruling gradient of 1 in 25 is provided.

Station yard Gradient: Station yard gradient is the minimum gradient provided in station
yard for easy draining of rainwater. Gradients are avoided as far as possible in station yard
due to following reasons

 In station yard, Bogies standing on gradients may start moving due to heavy wind and
may cause an accident.
 The locomotives will require an extra force of pull the train on gradients at the time of
starting the trains.
 In station yards, the maximum limit of the gradient is fixed as 1 in 400 and minimum
gradient recommended is 1 in 1000 for easy drainage of rainwater.

Grade compensation on curves:

Grade compensation on curves is the reduction in gradient on curved portion of a track. On

curves extra pull is required to pull the train due to more tractive resistance. It is expressed as
percentage per degree of curve. The grade compensation provided on Indian Railways is as
follows

 B.G. curves – 0.04 percent / degree of curve

 M.G. curves – 0.03 percent / degree of curve
 N.G. curves – 0.02 percent / degree of curve

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Super elevation or Cant

Super elevation or cant (Ca or e ) is the difference in

height between the outer and the inner rail on a
curve. It is provided by gradually lifting the outer
rail above the level of the inner rail.

The inner rail is taken as the reference rail and is

normally maintained at its original level. The inner
rail is also known as the gradient rail.

Ca = V²G /Gr

V= speed of train in m/s G = Gauge in meter

R = Radius of curve in meter g = acceleration due to gravity in m/s²

The main functions of super elevation are the following.

 To ensure a better distribution of load on both rails
 To reduce the wear and tear of the rails and rolling stock
 To neutralize the effect of lateral forces
 To provide comfort to passengers

Cant deficiency: Cant deficiency (Cd) occurs when a train travels around a curve at a speed
higher than the equilibrium speed. It is the difference between the theoretical cant required for
such high speeds and the actual cant provided.

Negative Cant: Negative Cant is a unique situation which occurs when the main line lies on
a curve with a branch line turnout of contrary flexure. It is a contradictory situation where the
inner rail is raised above the outer rail.

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Coning of Wheels: It providing an outward slope of 1 in 20 to the treads of wheels of rolling

stock is known as the coning of wheels.

The coning of wheels is provided to keep the vehicle in the central position with respect to
the track and helps the vehicle to move smoothly on the straight and curved track.

Coning of wheels is done to achieve the following object:

 To reduce the wear and tear of the wheel flanges and rails.
 To prevent lateral movement of trains.
 To prevent the wheels from slipping to some extent.

Tilting of Rails: It is placing the rails of a track at an inward slope of 1 in 20 is called tilting
of rails. The main object of tilting of rails is to reduce the wear on inside edges of rails in a
track. The required tilt is provided at rail seats in bearing plates, chairs and metal sleepers at
the time of their casting.

Advantages of Tilting of Rails

 The tilting of the rails enhances the life of both the sleepers and the rails.
 The tilting of rails helps to hold the gauge in the correct position.

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POINT AND CROSSING

Points and Crossing is the special arrangement provided

on railway track to facilitate trains to be diverted from one
track to another.

Turn Out: Turnout is an arrangement of points and

crossings with lead rails by which trains may be diverted
from one track to another moving in the facing direction.

A turnout is left handed or right handed as the train taking the turnout in the facing direction
is diverted to the left or right of the main line.

Right hand turnout: The train from main track is diverted to the right of the main route in
facing direction.

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Left hand turnout: The train from main track is diverted to the left of the main route in
facing direction.

Crossings: A crossing or frog is a device introduced at the point where two gauge faces cross
each other to permit the flanges of a railway vehicle to pass from one track to another.

Or

The arrangement made of intersection of two rails to permit the wheels of vehicle moving
along the track to pass over one or both of the rails of the other track with maximum safety
and minimum disturbance to the wheel is called crossing or frog.

Crossing on the basis of angle crossing are classified as follows.

1. V-Crossing or Acute angle crossing

2. Diamond Crossing or Obtuse angle crossing
3. Square Crossing

TRACK JUNCTION

Track junctions are created by the combination of points and crossings. The main function
of track junctions is to transfer the train from one track to another or to facilitate the crossing
of trains from one track to another.

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There are different types of track junctions depending on the traffic requirements,These
include

1. Turnout, 2. Diamond Crossing, 3. Scissor Crossover, 4.Cross over etc.

Diamond Crossing: When two track of same gauge

or different gauge cross each other at an angle is
known as diamond crossing.

Scissors Crossing: When two cross overs are laid

between two tracks it is known as scissors crossing
or double crossing.

Cross over: The arrangement made to divert a

train from one track to anther parallel track is
called cross over, It’s requires two sets of switches
and two crossings.

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SIGNALS
Signal means some pre-decided indications those
are used to control the train operation in safe
mode. The signals are provided to achieve the
following,

 To regulate the arrival and departure of

train
 To ensure the safety between trains which cross or approach each other
 To ensure safe and effective shunting
 To ensure safety cross - traffic at road - rail crossing
 To guide the trains during maintenances and repairs of track

Signals are classified according to two categories,

1. According to function – stop, warner signals, shunting signals and coloured light
signals.

Stop signals

Warner signals

Shunting signals

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Coloured signals

2. According to the locations-

 Reception signals - Outer signals and Home signals

 Departure signals - Starter signals and Advance starter signals.

Interlocking : Interlocking means an arrangement of signals, points and other appliances,

operated from a panel or lever frame, so inter-
connected by Mechanical locking or Electrical
locking or both that their operation must take
place in proper sequence to ensure safety.

The basic principles of interlocking are as

follows: -

1. It shall not be possible to take "off"

conflicting signals.
2. It shall be possible to take the "off"
Signal for a running line only when:

 All the points are correctly set.

 All the facing points are locked (at
site).
 All the interlocked level crossing gates are closed and locked against road traffic.
 The isolation is ensured.

Types of Interlocking

1. Mechanical Interlocking.
2. Electro Mechanical Interlocking.
3. Panel Interlocking (Relay)
4. Route Relay Interlocking.
5. Solid State Interlocking(SSI)

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STATION YARD

Station Yard is a place on the track where train stops for clearing passengers and
goods traffic.

Classification of Station Yard

1. Passenger yard - The main function of passenger yards is to provide facilities

for the safe movement of passengers and passenger bogies. Passenger
platforms are used as passenger yards.

2. Goods yard - The yards which are provided for receiving, loading and
unloading the goods and for the movement of goods vehicles, are called goods
yards. Goods platforms are treated as goods yards.

3. Marshalling yard- The arrangement made with an elaborate set of sidings for
sorting of wagons at important stations according to traffic requirements, is
called marshalling yard. The important functions of a marshalling yard are:
reception, sorting and departure.

4. Locomotive yard- The yards in which locomotives are housed for serving and
alos for coaling, watering, repairing, oiling, cleaning etc. are called locomotive
yards. Loco yards are generally constructed on the same sides as the
marshalling yard.

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