Sleepers and Ballast

 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.

 Sleepers - Functions
 Holding rails to correct gauge and alignment.
 Firm and even support to rails.
 Transferring the load evenly from rails to wider area of
ballast.
 Elastic medium between rails and ballast.
 Providing longitudinal and lateral stability

 Sleepers - Requirements
 The sleepers to be used should be economical, i.e they should
have minimum possible initial & maintenance cost.
 Moderate weight – easy to handle.
 Fixing & removing of fastenings should be easy.
 Sufficient bearing area.
 Easy maintenance & gauge adjustment.
 Track circuiting (electric insulation) must be possible.
 Able to resist shocks & vibrations.

 Sleepers - Types
 Timber or Wooden Sleepers
 Metal Sleepers
 Cast iron sleepers
 Steel sleepers
Concrete sleepers
 Reinforced concrete sleepers
 Pre - stressed concrete sleepers

Timber or Wooden Sleepers
Advantages
 Easy to manufacture and handling.
 Suitable for track circuited area.
 Can be used with or without ballast.
 Suitable for all types of ballast.
 Fittings are few & simple in design.
 Alignment can be easily corrected.
 Easily available in all part of India.

Timber or Wooden Sleepers
Disadvantages
 Lesser life (12-15 years)
 Liable to damage by better packing.
 Difficult to maintain the gauge.
 Susceptible to fire hazards.

 Sleepers - Types…..
Description of Wooden Sleepers
Size of wooden sleepers in mm :
B.G. : For ordinary track 2750x250x130 (9’x10”x5”)
Durable and non durable types of sleepers.
Life of Sleeper:
Durable –19 years (B.G.) / 31 years (M.G.)
Non-Durable - 12 to16 years.

Cast Iron Sleepers
Type of Cast Iron Sleepers:
 C. I.(Cast iron Pot or Bowl Sleepers
 C S T- 9 Sleepers (Cast iron sleeper)

 C. I. Pot or Bowl Sleepers

 C S T- 9 Sleepers:
cast iron component has a shape combining the
pot, bowl and plate. Widely used in India.

Advantages
 Uniform in strength & durability
 Easy to manufacture and handling.
 Gauge can be easily adjusted & maintained.
 It should be economical, as life is longer.
 Alignment can be easily corrected.
 Not susceptible to fire-hazards.
 Frequent renewal is not required.

Disadvantages
 More ballast required.
 Not suitable for high speed route.
 Lesser lateral stability.
 Not fit for track circuited area.
 Tie bars weakened by corrosion.
 Fittings required are greater in number & difficult to
maintain and inspection.

 Steel sleepers
Advantages
 Longer life (30 to 40 years).
 Better Stability.
 Lesser damage during handling / Transport.
 Easy to maintain Gauge.
 Simple Manufacturing Process.
 High Scrap value.
 They are not attacked by vermin's.
 They are not susceptible to fire hazards.

 Steel sleepers
Disadvantages
 Liable for corrosion.
 Not fit for track circuited area.
 Develops cracks at rail seat during service.
 The overall cost of steel sleepers is more than that of
timber sleepers.
 Fittings required are greater in number & difficult to
maintain and inspection.

 Concrete sleepers
Advantages
 Longer life ( 40 to 60 years).
 Better Stability.
 Lesser damage during handling / Transport.
 Easy to maintain Gauge.
 No chances of damage by fire/ corrosion
 No possibility of theft.
 No chances of gauge widening.
 They are not attacked by vermin and natural decay.
 There is no difficulty in the track – circuiting.

 Concrete sleepers
 Disadvantages
 Handling and laying is difficult being heavy.
 Damage is very heavy in case of derailment.
 No scrap value.
 Not suitable for manual packing.
 They damage the bottom edge during the packing.

 Sleepers – Spacing &Density…..
 The space between two adjacent sleepers determines the
effective span of the rail over the sleepers.
 It Depends on carry the axle load & lateral thrust.
 The number of sleepers in a track is indicated by the
number per rail length.
 More number of sleepers provides the more is the lateral
stability to the track.
 The number of sleepers per rail varies in India from
M+4 to M+7 for main track, where M = length of rail in
meters.

 Sleepers – Spacing …..

 Ballast …..
It is a layer of broken stone, gravel, moorum or any other gritty
(sand) material placed & packed below & around sleepers for
distributing the load from the sleepers to the formation & for
providing drainage as well as giving longitudinal & lateral
stability to the track.

 Ballast - Functions
 Provide level & hard bed for sleepers.
 Hold Sleepers in position.
 Transfer & distribute load to wide area.
Provide elasticity & resilience to track.
 Provide longitudinal & lateral stability.
 Provide effective drainage.
 Maintain level & alignment of track.

 Ballast - Requirements
1. It should be tough and should not crumble under heavy
loads.
2. It should be cubical shape & angular shape with sharp
edges.
3. It should be able to non-porous & non-water absorbent
particles of ballast are usually more durable due to better
resistance .
4. It should not make the track dusty or muddy.
5. It should offer resistance to abrasion and weathering.
6. It should not produce any chemical reaction with rails and
sleepers.

 Ballast - Requirements…..
7. It should provide good drainage system.
8. The size of stone ballast should be 5cm for wooden sleepers,
4cm for metal sleepers & 2.5 cm for turnouts & crossovers.
9. It should be cheep & economical or the ballast should be
available in nearest quarries.
10. In short, the ballast should be such which fulfils the
characteristics of strength, clean ability, durability, economy
& stability.

 Ballast - Types…..
 Broken Stone
 Sand
 Blast furnace slag or cinders
 Soft aggregate like moorum & gravel
 Kankar (lime agglomerate which is common in certain clayey
soils and is dug out of the ground)
 Brick ballast

1. Broken Stone
 Mostly used in Indian railways.
 Procured from hard stones like granite, quartzite, hard
trap etc.
 Economical in long run.

Ballast – Types…
2. Sand
 It is cheap and provides good drainage.
 The best sand consist of a good quantity of fine gravel &
sand which is used on narrow gauge (N.G) tracks.
 Its blowing effect due to vibration.
 The sand gets into the moving parts and on the track and
causes heavy wear.
 hence the sand laid is covered with stones, bricks to avoid
blowing about too much.

3. Blast Furnace Slag
 It is used in yards, sidings etc,
It is used as initial ballast in new
construction.
 Cheap & easily available.
 But its corrosive, harmful for steel sleepers & fittings.
4. Moorum
 It is the soft aggregate & is the result of decomposition of
laterite & has a red & sometimes a yellow colour.
Also used as blanketing material on black cotton soil.
 Cheap & easily available.
 But its corrosive, harmful for steel sleepers & fittings.

 Ballast - Size…..
 The size of ballast used varies from 1.9 cm to 5.1 cm.
 The best ballast is that which contains stones varying in size
from 1.9 cm to 5.1 cm with reasonable proportion of
intermediate sizes.
 The exact size of the ballast depends upon the type of
sleeper used and location of the track as below.
• Ballast size for wooden sleeper tracks = 5.1 cm
• Ballast size for steel sleepers tracks = 3.8 cm
• Ballast size for under switches & crossings = 2.54cm

Ballast - Section
 The section of the ballast layer consist of depth of ballast
under the sleepers & the width of the ballast layer.
 The depth of the ballast under the sleepers is an important
factor in the load bearing capacity & uniformity of distribution
of load.
 The width of the ballast layer is also important as the lateral
strength of track depends partly upon the quantity of ballast
used at the ends of the sleepers.

Ballast – Depth
 Minimum depth of ballast = 1/2 (c/c Sleepers Spacing – Width
of sleepers).
 for example, the sleeper spacing 65 cm & width of sleeper
is 25 cm, the calculate above equation minimum depth of
ballast is 20 cm

 Details of Ballast Sections…..
Sl.no Dimensions B.G M.G N.G
1 Width of Ballast 3.35 m 2.25 m 1.83 m
2 Depth of Ballast 20 to 25 cm 15 to 20 cm 15 cm
3
Quantity of stone
ballast per meter
length
1.036 Cu.m 0.71 Cu.m 0.53 Cu.m

Traction & Tractive Resistances
The train consists of two units the locomotive(Or engine)
which provides power for driving force and the trailing unit
which consists of passenger compartments or goods wagons.
Definition : The source through which the locomotive drives
power is called traction.
Sources : - Steam, Diesel fuel & Electric supply (AC/DC)
 Traction / Power has a bearing upon.
 Load carrying capacity, speed, economy and efficiency of the
track.

 Tractive Resistances
Definition : The number of forces which resist the movement
and speed of a train .
 The Classification of Tractive Resistances..
a) Train resistance (RT1)
b) Resistance due to track profile (RT2)
c) Resistance due to starting & acceleration (RSA)
d) Wind resistance (Rw)

 Tractive Resistances
Train resistance (RT1): Train resistances can further be
classified in following categories.
 Resistances Independent of speed (Rt1).
 Resistances dependent on speed (Rt2).
 Atmospheric resistances (Rt3)
Total Train Resistance (RT1) = Rt1 + Rt2 + Rt3

1) Resistances Independent of speed (Rt1): This resistance are
caused due to.
 a) Journal friction: This is dependent on type of bearing,
lubricant used, the temperature and condition of the bearing.
 b) Frictional resistance: Friction between steel wheels & steel
rails.
 c) Track resistance :Track resistance is caused due to the wave
action of rails.
 d) Resistance due to internal parts: it consists of resistance
between rim of wheels, resistance of other moving parts and
resistance of locomotives and wagons.
Computation : Rt1 = 0.0016 w
where “ w ” is weight of train in tonnes.

2) Resistances Dependent on speed (Rt2):This resistance are
caused due to.
 Track Irregularities.
 Vertical movement of wheels on rails (Improper joints &
maintenance)
 Flange action (oscillations, sways etc): on a railway track, the
locomotive moves in zig-zag manner within the limits of wheel
gauge tolerance.
Rc α (1/ length of rigid wheel base)
Rc α (speed of the train)2
Computation : Rt2 = 0.00008 w v
where w = weight of train in tonnes.
v = speed of train in km.ph

3) Atmospheric resistances (Rt3)
This resistance is developed on the ends & sides of the train,
when wind velocity is considered to be zero. It is low at lower
speed, but increases as the square velocity as the speed increases.
Computation : Rt3 = 0.0000006 w v2
v = speed of train in km.ph
Total Train Resistance (RT1) = Rt1 + Rt2 + Rt3
Total Train Resistance (RT1)
= 0.0016 w + 0.00008 w v + 0.0000006 w v2

2) Resistance Due to Track Profile (RT2): Resistance due to track
profile can be further classified in two categories.
a)Resistances due to gradients (Rg).
 b) Resistances due to curves (Rc).

a) Resistances due to gradients (Rg)
Whenever a train has to move along a rising gradient, it
has first to overcome the resistance which it experiences due to
rising gradient.
Computation : Rg = weight * percentage of slope
Rg = weight * tan θ
Rg = w *g
g = gradient

b) Resistances due to curves (Rc)
This resistance comes into consideration when the train
moves on the curve path.
The curve resistance is caused due to following reasons.
 Rigidity of wheel base.
Increased pressure on the inner rail due to insufficient super
elevation & greater pressure on the outer rail it move than the
desired elevation is provided.
 Poor track maintenance, improper gauge, poor alignment,
when out rails, high or low joints, kinks etc. further increase this
resistance.

 The curve resistance increases with the increases in the speed of
the train.
 Recommended values of curve resistances.
Computation : For B.G Rc = 0.0004 w * D
For M.G Rc = 0.0003 w * D
For N.G Rc = 0.0002 w * D
D = degree of the curve.

3) Resistance Due to Starting & Accelerating (RSA):
These resistance are experienced by a train at the stations
while starting accelerating and decelerating. These resistances
are obtained by the following expressions.
 Resistances due to Starting (Rs). = 0.15 w1 + 0.005 w2
 Resistances due to Acceleration (RA). = 0.28 .w.a
where, w1 = weight of a locomotive in tonnes
w2 = weight of a vehicle in tonnes
w = total weight of train in tonnes
a = acceleration in km/ph/sec

4) Wind Resistance (Rw):
In this, the resistance is divided into two components – one
which helps in the forward movement of train (i.e., the
component of the wind velocity in forward direction) and the
other which opposes the motion of the train (i.e., the component
of the wind velocity in backward direction).
Computation : Rw = 0.000017 aV2
where a = exposed area of the train in sq.meters
V = speed of wind in km.ph

 Hauling Capacity Of A Locomotive
 Defined as the load that can be handled by the locomotive.
It can be computed as a product of the coefficient of friction and
weight on the driving wheels
 The coefficient of friction between the driving wheels and the
rails, depends largely upon the following two factors.
 condition of the rail surface, &
 speed of the locomotive.
Sl.no Condition of Rail Surface Coefficient of Frication
1 Very wet or very dry 0.25
2 Greasy 0.03
3 Average dampness 0.166
4 In Tunnels and frosty weather 0.125

 Hauling Capacity Of A Locomotive
 The coefficient of frication increases with decrease in speed and
decreases with increase in speed.
 With respect to speed it varies between 0.1 at high speeds to 0.2
at low speeds.
Computation : Hauling capacity = µ * w * n
= µ * W
where :- µ = coefficient of friction w = weight on driving axle
n = No. of pairs of driving wheels
W = total weight on driving wheels
 Maximum axle load in India
 B.G = 28.56 Tonnes
 M.G = 17.34 Tonnes
 N.G = 13.26 Tonnes

 Track Fittings & Fastenings
Track fittings and rail fastenings are used to keep the rails in
the proper position and to set the points and crossings or
properly. They link the rails endwise and fix the rails either on
chairs fixed to sleepers or directly on to the sleepers.
 Types
 Rail to Rail Joining --- Fish plates, bolts, nuts.
 Rail to wooden sleeper --- Dog Spike, Screw spike,
fittings Bearing plate & Fang bolts.
 Rail to steel through sleeper -- Loose Jaws, Keys & Liners.
 Rail to CI(Cast Iron) sleeper--- Tie bars, cotters
Elastic fastenings --- Elastic or Pandrol Clip,
Rubber pad & nylon liners

 Track Fittings & Fastenings....
 Fish Plates;
 Fish plates are used in rail joints to maintain the continuity of
the rail & to allow for any expansion or contraction of the rail
caused by temperature variations.
 They maintain the correct alignment of the line both
horizontally & vertically.

 Fish Plates - Requirements
 They must support the underside of the rail and top of the foot.
 They should allow a free movement of rails for expansion &
contraction; for this purpose, they should not touch the web of
the rail.
It should be bear the stress for lateral & vertical bending
moments.
 They should be hold the ends of the rail both laterally in line &
vertically in level.
It should be against the wear.

 Spikes
 For holding the rails to the wooden sleepers, spikes of various
types are used.
 These can be used with or without bearing plates below the
rails.
 Spikes – Requirements:-
 It should be strong enough to hold the rail in position and
should have enough resistance to motion
The spike should be as deep as possible, for better holding
power.
The spike should be easy in fixing and removal from the sleeper.
 The spike should be cheep in cost.
 It should be capable of maintaining the gauge

 Types of spikes:
a) Dog spikes
b) Screw spikes
c) Round spikes
d) Standard spikes
e) Elastic spikes

 Dog Spikes
 For holding the F.F rails to a wooden sleepers, commonly used.
 The shape of head of spike resembles with ear of the dog and
hence the nomenclature as Dog spike.
 The section of the spike is square – shape and bottom part is
either pointed, blunt or chisel shaped.
 They are cheapest, easy in fixing and
removing from sleepers & maintain
a better gauge than screw spikes.

 Screw Spikes
 These are screws with V-threads used to fasten the rails with
timber sleepers.
 The head is circular with a square projection.
 It is have more than double holding power to that of dog spikes
& can also resist lateral thrust in a better way as compared to
dog spikes.
 It is costly Compared other spikes.

 Bearing Plates
 Bearing plates are rectangular plates of Mild Steel (M.S) or
Cast Iron (C.I ), and are used below F.F rails to distribute the
load on a larger area of timber sleepers particularly of soften
variety.
 It is used to distribute the load coming on rails to the sleepers
over a larger area and thus to prevent sinking of the rail in the
soft wooden sleepers.
It is better maintenance of gauge, if bearing plates are used, is
possible.

 Pandrol Clip or Elastic Clip
 For the holding rails to a concrete sleepers, commonly used.
 Fit & forget type.
 It is rail fastenings is a pre-assembled system, developed in
response to the growing need for fast, efficient track installation
& reduced maintenance costs.
 At the point contact, it causes
indentation on rail foot, one of the
draw back.

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