Railway engineering part1

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.
2GRK, Asst. Professor, SPEC

History of Railways

 Railways were first introduced to India in
1853 from Bombay to Thane
 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 one of the world's largest
commercial or utility employers, by number of
employees, with over 1.4million employees. As
for rolling stock, IR holds over 39,281Freight
Wagons, 59,713Passenger Coaches and
9,549Locomotives(43 steam, 5,197 diesel and
4,309 electric locomotives).
 As of 31 March 2013, 23,541km (14,628mi)
(36%) of the total 65,000km (40,000mi) km
route length was electrified. Since 1960, almost
all electrified sections on IR use 25,000 Volt AC
traction through overhead catenary delivery.

Components Permanent Way
 Permanent way = The railway track
 Typical components
 Rails
 Sleepers (or ties)
 Fasteners
 Ballast (or slab track)
 Sub grade

Permanent Way

Components

Cross section of a railway track

RAILS
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 rail:
The main requirements of an ideal rail section are as under:
 The section of the rail should be such that the load of the
wheels is transferred to the sleepers without exceeding the
permissible stresses.
 The section of the rail should be able to withstand the
lateral forces caused due to fast moving trains.
 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.
 The centre of gravity of the rail section should preferably
coincide the centre of the height of the rail so that
maximum tensile and compressive stresses are nearly
equal.

 The web of the rail section should be such that it can
safely bear the vertical load without buckling.
 The head of the rail should be sufficiently thick for
adequate margin of vertical wear.
 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.
 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.
 The surfaces for rail table and gauge face should be
sufficiently hard to resist the wear.
 The contact area between the rail and wheel flange
should be as large as possible to reduce the contact
stresses.

 The overall height of the rail should be adequate
to provide sufficient stiffness and strength as a
simply supported beam.
 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.
 The section moduli 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.
 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

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.

SLEEPERS

 Sleepers are members generally laid transverse
to the rails, on which the rails are supported &
fixed, to transfer the loads from the rails to the
ballast and the sub grade.

Functions of Sleepers
In a railway track, sleepers perform the following functions:
 To hold the rails at 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.
 To support the rails firmly and evenly throughout.
 To distribute the load transmitted through rails over large area of
ballast underneath or to the bridge girders as the case may be.
 To hold the rails to proper level in turnouts and crossovers, and at
1 in 20 inward slope along straight tracks.
 To provide and elastic medium between the rails and ballast and
also to absorb the vibrations caused due to moving axle loads.
 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 the rails.

Requirements of a good Sleeper
A good sleeper should meet the following requirements:
 The initial cost and the maintenance cost of the sleepers
should be low.
 The fittings required for fixing the rails on to the sleepers,
should be simple which can be easily adjusted during the
maintenance.
 The crushing strength of the sleepers should be more with
moderate weight.
 They should be able to maintain a perfect alignment, gauge
and levels of the rails and should afford efficient adjustment
and maintenance.
 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.

 The sleeper spacing should be such as to remove and
replace the ballast during regular maintenance
operation.
 They should be capable to resist the shocks and
vibrations caused due to fast moving vehicles at high
speeds.
 The sleepers should be strong enough to withstand the
pressure during packing process.
 The sleepers should be of such a design that they
remain in their positions and do not get disturbed due to
moving trains.
 The material used for the sleeper be such that it does
not attract the sabotage and the theft qualities.

Types of Sleepers
1. Sleepers based on the materials
 Timber sleepers
 Steel sleepers
 Cast iron sleepers
 R.C.C sleepers
 Pre-stressed concrete sleepers.
2. 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

Timber sleepers (Wooden sleepers)
Ideal type and universally used they are two
categories of hard wood sleepers such as Sal, Teak
and soft wood sleepers such as deodar, chir, treated
timbers are use in this categories.

Advantages of Wooden Sleepers:
 They have proved very useful for heavy loads and
high-speed trains.
 They are cheap and easy to manufacture.
 They can be handled easily without any damage.
 They maintain the correct alignment.
 They are most suitable for track circuiting.
 They can be used with or without ballast.
 They can be used for gauntlet tracks.
 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.
 They do not maintain the gauge accurately.
 They easily develop cracks with beater packing.
 They require the highest maintenance cost as compared to
other types of sleepers.
 They get easily disturbed from their positions under heavy
loads.
 They need special treatment for fire protection.
 Their scrap value is low.
 They are not suitable for modern LWR track because of
their lighter weight.

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:
 They are manufactured by a simple operation.
 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.
 Less number of fastenings are required and that
too simple in nature.
 The maintenance and adjustment of gauge are
easy as compared to the other of sleepers.

 These sleepers are rolled sections in one
piece.
 Their life is longer than that of other types of
sleepers.
 They provide better lateral rigidity to the
track.
 They are not attacked by vermin’s.
 They are not susceptible to fire hazards.
 Their scrap value is good.

Disadvantages of Steel of Sleepers
The steel sleepers possess the following
disadvantages:
 They get easily rusted and corroded.
 They develop cracks at rail seats or near lugs.
 Their lugs get broken easily.
 The steel sleepers do not provide effective track
circuiting
 The steel sleepers can only be for the type of
rails for which theses are manufactured.
 These develop the tendency to become center
bound because of slope at both ends.
 The overall cost of steel sleepers is more than
that of timber sleepers.

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 upto50-60 years.
 High scrape value as they can be remoulded.
 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 of 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. 47GRK, Asst. Professor, SPEC

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).
 In India the sleeper density varies from M+4
to M+7 for main tracks.
where, M=length of the rail (if N in place
of M is used, then ‘N’ is the length of the rail
in yards).
 In Britain, N+4 sleepers are used.
 In America the sleeper density varies from
M+9 to M+11.

1. Find out the expression for sleeper density for a B.G
track if, 19 sleepers are used under a rail length.
Ans:
Length of the rail for B.G track= 12.8 m
Sleeper density = M+x
where,
M=length of the rail in meters
x= a factor depending up on several factors
=> 19= M+x
=> 19=13+x
=> x=6
The expression for sleepers density = M+6.

2. Using a sleeper density of M+5. find out the
no. of sleepers required for constructing a
railway track 640m long.
Ans: Length of the Rail B.G = 12.8m
Total no. of rail required = 640/12.8
= 50 no’s.
As per,
Sleeper density M+5 the no. of sleepers
under each rail= 12.8+5
= 17.8 = 18 no’s.
Total no. of sleepers =18 X 50= 900 no’s.

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.

Coning of wheel
 The surface of wheels are made in cone shape at an inclination
of 1 in 20 is known as coning of wheels.
 This allows a train to take a turn without slipping off its tracks.

Coning of wheel

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:
 It should resist crushing under dynamic loads.
 The designed depth of the ballast should be able to distribute
the eight of passing trains on the formation underneath
uniformly.
 It should not make the track dusty due to powder formation
under dynamic wheel loads.
 It should be reasonably elastic.
 It should have resistance to abrasion and weathering
 It should be non-porous to provide durability to the ballast.
 It should hold the sleepers laterally and longitudinally under
all conditions traffic, especially on the curves.
 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:
 It provides a hard and level bed for the sleepers.
 It holds the sleepers in proper position during the
passage of moving trains.
 It provides to some extent an elastic bed for the track.
 It transmits and distributes the moving load of the
trains from the sleepers to the formation uniformly.
 It protects the formation surface from direct exposure
to sun, rain and frost.
 It provides a proper drainage to the track, keeping the
sleepers in dry condition.

Functions of Ballast
 It obstructs the growth of vegetations at the track
formation.
 It provides proper super elevation to the outer rail on
curves.
 It provides an easy means for correcting the
unevenness of the track.
 It provides the lateral and longitudinal stability to the
track .
 It protects the sleepers from capillary moisture of
formation.
 It provides a media for absorption of all impacts
caused by rolling stock.

Types of Ballast
Keeping in views 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. 64GRK, Asst. Professor, SPEC

(4) Sand:
 Best materials for ballas.t
 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 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.

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).

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, Sri Lanka, Brazil,
Argentine,etc.50% India’s railway tracks have
been laid to this gauge.

Suitability :-
Broad gauge is suitable under the following
Conditions :-
 When sufficient funds are available for the
railway project.
 When the prospects of revenue are very
bright.
 This gauge is used for tracks in plain areas
which are densely populated i.e. for routes of
maximum traffic intensities and at places
which are centres 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:-
 When the funds available for the railway
project are inadequate.
 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 :-
 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.
 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
 The most effective advantage of breaking the
gauge is to render the railway an economical
and profitable concern.
 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
 It causes much inconvenience to the passengers while
changing the train at station, with change of gauge.
 It causes delay in movement of people and goods.
 It results in wastage of time.
 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.
 It requires the provision of extra and costly trans
shipment yards, go-downs, sheds, etc. at every
junction station having change of gauge.
 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.

TRACK FITTINGS AND
FASTENINGS

FASTENING SYSTEM
 Rail fastening system is a means of fixing rails
to sleepers
 Used to keep rails in proper position
Important fittings are:
1. FISH PLATES
2. SPIKES
3. BOLTS
4. CHAIRS
5. BLOCKS
6. KEYS
7. PLATES

FISH PLATES
 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.
 Maintain the continuity of rails & to allow for expansion
and contraction of rail due to temperature difference.
 Maintain correct alignment of line both horizontally&
vertically.
 Fishplate is a small copper or nickel silver plate that slips
onto both rails.

FISH BOLTS
BONE SHAPED
FISH PLATE

REQUIREMENTS OF FISH PLATES
 They must support the underside of rail and top of the foot.
 They should allow free movement of rails for expansion &
contraction. For this They should not touch the web of rail.
 They should bear stresses due to lateral & vertical bending
moments.
 They should hold ends of rail both laterally in line and
vertically in level.
 They should not wear due to impact, expansion & contraction.
 Length of fish plate should not exceed 457mm in India.

FISH BOLTS
 Holes are drilled through plates and web of rails and
then fish bolts and nuts are provided in these holes.
 Alternate holes are made elongated and oval shaped so
that bolts in the rails will not be turned by vibrations.
 Holes are made of larger diameter generally 5mm-
6mm to allow for expansion & contraction.

Bone shaped Fish
plateRail
Hole for Fish bolt

SPIKES
 To hold rails to wooden sleepers.
 A rail spike is a large nail with an offset head
that is used to secure rails and base plates to
sleepers.

REQUIREMENTS
The spike should be
 Strong enough to hold rail in position & enough
resistance to motion to retain its position
 Cheap in cost
 Deep as possible for better holding power
 Easy in fixing and removal from sleepers
 Capable of maintaining the gauge

DOG SPIKES
 Commonly used.
 Hold rail flanges with timber sleepers.
 Shape of head of spike resembles ear of dog,
hence called dog Spike.
 Section of spike is square – shape & bottom
part is either pointed or chisel shaped.
 Cheapest, easy in fixing and removing from
sleepers.
 Maintain better gauges.

DOG SPIKES

Important points to be noted:
1. Driving:
 Plays an important role in determining the holding
power of spike.
 Driven in a staggering manner. If spikes are placed
opposite to each other they have a tendency to split
sleeper and have less holding power
2. Blows:
 Blows to spike should be centric & regular. Otherwise
result in larger holes.
DOG SPIKES

3. Boreholes:
 Spikes driven into bored holes have slightly smaller
section than boreholes & have greater holding power than
when driven without boreholes and also crushing of
sleepers can be reduced.
4. Number:
 No. of dog spikes is 2 per each rail.
 For heavy traffic, upto 3-4.
 On bridge sleepers, no. is 4 per each rail joint.
DOG SPIKES

5. Auger
 Dog spikes are bored using 13mm auger.
 Holes are bored vertically through sleeper
 Verticality is essential otherwise connections will be
loose , gauge will be widened , hole become widened and
sleeper will decay.
6. Plugging
 Due to heavy traffic, when dog spikes gets loose it is
driven out and hole is plugged with wooden plug.
 Another hole is bored and dog- spike is re-driven there.
 Plugged holes are called spike killed holes.
DOG SPIKES

SCREW SPIKES
 Tapered screws with V- threads used to fasten
rails with timber sleepers.
 Head is circular with square projection.

 Holding power is double that of dog- spike.
 Resist lateral thrust in better way.
 More costly.
 Gauge maintenance is more difficult
 Driving operations are similar to dog -spikes
SCREW SPIKES

ROUND SPIKES
 Head either cylindrical or hemispherical.
 Used for fixing chairs of bull headed rails to
wooden sleepers.
 Limited use only.

ELASTIC SPIKES
 To overcome the problems of dog- spikes
head absorbs the wave motion of rail without
getting it loose.
 Provide better grip and result in reduction of
wear and tear of rail.
 Commonly used in British railways.

ELASTIC SPIKES

BOLTS
1. FANG-BOLT
 Alternative to round spikes.
 Not in much use due to difficulty in fixing and
removing bolt.
 19mm in diameter and of sufficient length to pass
through sleeper.

2. FISH BOLT
 Made of medium carbon steel.
 Length of bolt depends on type of fish plate used.
 Too much tightening is prohibited as it prevents free
expansion & contraction of rails.
 Nuts are made of sufficient length to provide a good
grip on the bolt with square or hexagonal shape.
BOLTS

CHAIRS AND KEYS
 For double headed & bull headed rails chairs are used to
support them in position.
 Made up of cast iron.
 Distribute load from rails to sleepers.
 Chairs have been fixed to the sleeper using wooden spikes
screws, fang-bolts or spikes.
 Chair consist of 2 jaws & a rail seat.
 Web of rail is held in inner jaw of chair and a key is driven
between rail and outer jaw of chair.

KEY
RAIL
CHAIR

 Chairs are fixed to sleepers using 3 spikes.
 Keys may be of wood or metal and may be either
straight or tapered.
 Wooden keys are cheap.
 Initial cost of steel keys is high. But life is about
ten times more than wooden keys. So steel keys
are preferred.
CHAIRS AND KEYS

STEWART’S KEY
 Steel plate bend in the form of letter E and a steel
wedge.
 Steel wedge to keep the key tight against rail web and
out.

BEARING PLATES
Rectangular plates of Mild steel or cast iron.
Used below flat footed rails to distribute the
load on a larger area of timber sleepers.
Placed below rails carrying heavy vehicles at
high speed.

Advantages:-
 Distribute load to sleepers over a large area and prevent
sinking of rail in soft wooden sleepers.
 Prevent destruction of sleepers due to rubbing action of rail,
increase life of sleeper.
 Help in firm and perfect holding of spikes to sleepers which
prevent shifting of rails.
 Better maintenance of gauge.
BEARING PLATES

Disadvantages:-
 Plates rattle when loose.
 When any hole for a spike is failed and a new hole is
to be made , all spikes in the bearing plate have to be
pulled out which affects good hold of spikes.
 When bearing plates are loose, they admit moisture
and result in mechanical wear of sleepers.
BEARING PLATES

Creep
 Creep is defined as the longitudinal movement of
the rail with respect to the sleepers.
 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.

Theories for the Development of Creep
Various theories have been put forward to explain the
phenomenon of creep and its causes, but none of them have
proved to be satisfactory. The important theories are briefly
discussed in the following subsections.
1. Wave Motion Theory:
 According to wave motion theory, wave motion is set up
in the resilient track because of moving loads, causing a
deflection in the rail under the load.
 The portion of the rail immediately under the wheel gets
slightly depressed due to the wheel load. Therefore, the
rails generally have a wavy formation.

 As the wheels of the train move forward, the
depressions also move with them and the
previously depressed portion springs back to the
original level.
 This wave motion tends to move the rail forward
with the train.
 The ironing effect of the moving wheels on the
wave formed in the rail causes a longitudinal
movement of the rail in the direction of traffic
resulting in the creep of the rail.

2.Percussion Theory
 According to percussion theory, creep is
developed due to the impact of wheels at the rail
end ahead of a joint.
 As the wheels of the moving train leave the
trailing rail at the joint, the rail gets pushed,
forward causing it to move longitudinally in the
direction of traffic and that is how creep develops.
 Though the impact of a single wheel may be
nominal, the continuous movement of several of
wheels passing over the joint pushes the facing or
landing rail forward, thereby causing creep.

3.Drag Theory
 According to drag theory, the backward
thrust of the driving wheels of a locomotive
has the tendency to push the rail backwards.
 While the thrust of the other wheels of the
locomotive pushes the rail in the direction in
which the locomotive is moving.
 This results in the longitudinal movement of
the rail in the direction of traffic, thereby
causing creep.

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, therefore creep develops in the direction
of traffic.
 In a single-line section, even though traffic moves in
both directions, the volume of the traffic in each
direction is normally variable.
 Therefore creep develops in the direction of
predominant traffic.

 Poor maintenance of track: Some minor factors,
mostly relating to the 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.

Effects of Creep
The following are the common effects of creep.
 Sleepers out of square: The sleepers move out of
their position as a result of creep and become out of
square. This in turn affects the gauge and alignment of
the track, which finally results in unpleasant rides.
 Disturbance in gaps get disturbed: Due to creep, the
expansion gaps widen at some places and close at
others. This results in the joints getting jammed.
Undue stresses are created in the fish plates and bolts,
which affects the smooth working of the switch
expansion joints in the case of long welded rails.

 Distortion of points and crossings: Due to excessive
creep, it becomes difficult to maintain the correct gauge
and alignment of the rails at points and crossings.
 Difficulty in changing rails: If, due to operational
reasons, it is required 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 interlocking: The interlocking mechanism of
the points and crossings gets disturbed by creep.
 Possible buckling of track: If the creep is excessive
and there is negligence in the maintenance of the track,
the possibility of buckling of the track cannot be ruled
out.
 Other effects: There are other miscellaneous effects of
creep such as breaking of bolts and kinks in the
alignment, which occur in various situations. 128GRK, Asst. Professor, SPEC

KINKS
 Kinks are the lateral shift in rails due to
movement of trains, loose joints and defective
gauge.

Measurement of Creep
 Creep can be measured with the help of a device
called creep indicator.
 It consists of two creep posts, which are
generally rail pieces that are driven at 1-km
intervals on either side of the track.
 For the purpose of easy measurement, their top
level is generally at the same level as the rail.
Using a chisel, a mark is made at the side of the
bottom flange of the rail on either side of the
track.

 A fishing string is then stretched between the two
creep posts and the distance between the chisel
mark and the string is taken as the amount of
creep.
 According to the prescribed stipulations, creep
should be measured at intervals of about three
months and noted in a prescribed register, which
is to be maintained by the permanent way
inspector (PWI).
 Creep in excess of 150 mm (6 in.) should not be
permitted on any track and not more than six
consecutive rails should be found jammed in a
single-rail track at one location. There should be
no creep in approaches to points and crossings.

Remedies or Prevention of creep
Following are the common methods adopted to prevent creep:
Pulling back the rails:
 If the creep is distinctly visible, the remedy is pull
back the rails to their original position.
 Start pulling the rails back to their original positions
by means of hooks provided through the fish bolt
holes of Rail.
 In pulling back the positions of joints relative to
sleepers must be maintained and both the rail joints
must be in their relative positions.
 Pulling back the rails is a very slow and tedious
process and is only possible when a small length is to
be dealt.

Provision of Anchors and Anti Creepers:
 The creep of the track can be prevented by use of
anchors 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 and
crossings.
 For creep of 7.5cm to 15cm in a month 4-anchors per
rail and for creep of 22.5cm to 25cm 6-anchors per used
in the Indian practice.
 If creep occurs in both directions, anti-creepers are
provided both on both the sides of sleepers, starting
from the center of the rail and should be fixed near the
joints.

Anchors and anti- creepers

Use of steel sleepers:
 Sleeper should be of such a type and with such
fittings that they effectively prevent the rail
from creeping on them.
 Secondly, the sleepers must have a good grip
with the ballast to resist the movement of the
sleepers in the ballast.
 Steel trough sleepers are the best for this
purpose .
 Increase in the number of sleepers will,
therefore, also help in the prevention of creep.

Adzing of Wooden Sleepers:
 In order to enable the rails to be slightly tilted inwards
at a cant of 1 in 20, wooden sleepers are required to be
cut to this slope at the rail seat before laying.
 This process of cutting the wooden sleeper at a slope of
1 in 20 is known as ‘adzing of the wooden sleeper’.
 It may be pointed out that adzing or cutting of a
wooden sleeper at a slope of 1in 20 is done with great
care, otherwise the slope will vary from sleeper to
sleeper resulting in a rough ride.
 The adzed surface of a wooden sleeper is treated with
coal tar to ensure proper protection of the surface.
 Normally, adzing of a wooden sleeper is done only
when bearing plates are not provided.

Rail joints
 Rail joints are necessary to hold together the
adjoining the ends of the rails in the correct
position, both in horizontal and vertical
planes.
 Rail joints form the weakest part of the track.
 It is observed that strength of rail joint is only
50percent of the strength of a rail.

Requirements of an ideal joint
The following are requirements should be met by an
ideal joint:
 The two rail ends should remain true in line both
laterally and vertically when trains move on the
track.
 The rail joint should be as strong as stiff as the
rail itself and should be elastic both laterally and
horizontally.
 The rail joint should provide enough space for
free expansion and contraction to account for the
effect of temperature variations.

 A good joint should be easily disconnectable
so that it can be easily taken out without
disturbing the whole track for the purpose of
changing rail or a fish plate.
 It should not allow the rail ends to get battered
in any case.
 It should be economical.

Types of Rail joints
1. Supported joint.
2. Suspended rail joint.
3. Bridge joints.
4. Staggered joint .
5. Square joint or Even joint.
6. Welded joints.
7. Compromise joint.
8. Insulated joint.
9. Expansion joint.

Supported joint:
 When the sleeper is placed exactly below the rail
joint, it is known as supported joint.
 It was expected that supporting the joint would
reduce the wear and tear of the rails, as there
would be no cantilever action.
 In practice, however, the support tends to slightly
raise the height of the rail ends. As such, the run
on a supported joint is normally hard.
 There is also wear and tear of the sleeper
supporting the joint and its maintenance presents
quite a problem.

Suspended rail joint
 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.
 This type of joint is generally used with timber
and steel trough sleepers on Indian foreign
railways.

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.

 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.
Staggered joint

Square joints or Even 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

Welded rail joints
 In this method the rails are joined by means of
welding.
 These are the best joints they fulfill all the
requirements of an ideal joint.

Compromise joint
 Where two different rail sections are required to be
joined together, it is done by means of fishplates
which fit both the rails.
 This type of joint is termed as compromise joint.

Insulated joint
 When insulating medium is inserted in a rail
joint to stop flow of current beyond the track-
circuited part, it is called insulated joint.

Expansion joint
 These are used for provision of both
contraction and expansion in rails.

Railway engineering part1

More Related Content

What's hot

Similar to Railway engineering part1

More from GARRE RAVI KUMAR

Recently uploaded

Railway engineering part1