2. Permanent Way
• Rail-road on which train runs
• Consists of 2 parallel RAILS placed at a
specified distance between them, &
FASTENED to SLEEPERS, which are
embedded in a layer of BALLAST of specified
thickness spread over the FORMATION.
4. Permanent Way - Requirement
• TRACK: resilient & elastic
• Drainage: stability, no water-logging
• Lateral Strength: shocks, vibrations
• Easy replacement of renewal of components
• Cost – minimum (construction operation &
maintenance)
5. Roadways vs. Railways
• Construction of route:
– RdW; suitable pavement of specified width provided with
shoulders on either side.
– RLW: pair of steel rails which are laid parallel to each other
on sleepers at fixed distance apart.
• Suitability to traffic:
– In RdW, routes are meant for movement of different types,
of traffic such as buses, trucks, scooters, rickshaws,
cycles, pedestrians etc.
– RLW routes are meant only for movement of trains.
6. Roadways vs. Railways
• Width of right-of-way:
– RdW routes require MORE width of right-of-way.
– RLW routes require LESS width of right-of-way.
• Starting and destinations:
– In RdW, starting and destination points of traffic
are NOT FIXED.
– In RLW, starting and destination points of trains
are ALWAYS FIXED.
7. Roadways vs. Railways
• Right of entry:
– In RdW, it is free to all vehicles because their
movements are not according to any schedule.
– In RLW, it is not free to all railway vehicles
because their movements are always according
to schedule.
• Strength of route:
– In RdW it is LESS.
– In RLW tracks it is MORE.
8. Roadways vs. Railways
• Elasticity:
– RdW routes do not require an elastic structure since they
are not to withstand impacts of heavy wheel loads.
– RLW routes require an elastic structure to withstand impact
of heavy wheel loads.
• Gradients and curves:
– In RdW, the routes can be constructed with steep
gradients & sharp curves. Thus, route length is LESS.
– In RLW, routes cannot be constructed with steep gradients
& flat curves. Thus, route length is MORE.
9. Roadways vs. Railways
• Tractive resistance:
– For RdW routes is high (5-6 times of railway).
– For RLW routes, it is low
• Load handling capacity:
– For road vehicles, it is less & at low speeds.
– For RLW vehicles, it is more and at high speeds.
10. Roadways vs. Railways
• Requirement of turning devices:
– In RdW , NO special turning devices are constructed for
turning vehicles on these routes.
– In RLW, special turning devices (points & crossings) are
constructed for turning vehicles on these routes.
• Operational control devices:
– In RdW , no special operational control devices in the form
of signaling and interlocking are required on these
routes for safe and efficient movement of vehicles.
– In RLW, these are REQUIRED for safe & efficient
movements of trains.
11. Roadways vs. Railways
• Suitability to transportation of people and goods:
– Suitable for SHORT DISTANCES (upto 500 km) is
convenient and cheap by roadway routes.
– Transport of people and heavy goods like raw materials,
coal, ores, etc. for LONG DISTANCE or manufacturing
concerns is convenient and cheap by railway routes.
• Adaptability to type and size of goods:
– All types and sizes of goods CANNOT BE HANDLED by
road vehicles.
– Almost all types and sizes of goods is handled by trains.
12. Roadways vs. Railways
• Suitability for hilly area:
– RdW vehicles are MORE suitable for hilly area.
– Railway vehicles are LESS suitable for hilly area.
• Employment potential:
– RdW have LESS employment potential.
– RLW have HIGH employment potential.
• Rate of accidents:
– In roadways, the rate of accidents is HIGH.
– In railways, the rate of accidents is LESS.
• Construction and maintenance cost:
– Cost of roadway vehicles is LESS.
– In case of railway vehicles, the cost is MORE.
13. Gauge
• It is the minimum distance between 2 rails.
• Indian Railways (IR) measures gauge as clear minimum
distance between the running faces of the 2 rails.
14. Name of
Gauge
Width (mm) Width (feet) Route Km % of Route
km
Broad Gauge
(BG)
1676 5’6” 40000 64
Metre Gauge
(MG)
1000 3’3.37” 20000 31
Narrow
Gauge (NG)
762 2’6” 4000 5
TOTAL 64000 100
15. Choice of Gauge
• Cost Consideration
• Traffic Consideration
• Physical Feature of Country – adopt steeper
gradient & sharper curves for a narrow gauge as
compared to a wider gauge.
16. Cost Consideration
• There is a marginal increase in cost of track if a
wider gauge is adopted
– Proportional increase in cost of land acquisition,
earthwork, rails, sleepers, ballast & other tracks.
– Cost of bridges, culverts & tunnels increases only
marginally due to wider gauge.
– Cost of constructing station buildings, platform, staff
quarters, level crossings, signals, etc.
– Cost of rolling stock is independent of the gauge for
carrying same volume of traffic.
17. Traffic Consideration
• Volume of traffic depends on Size of Wagons &
Speed & hauling capacity of trains
– Wider gauge carry larger wagons & coaches & hence
carry more traffic.
– Wider gauge have higher speeds.
– Type of traction & signalling equipment required are
independent of the gauge.
19. Coning of Wheels
• Tread of wheels of a railway vehicle is not made flat, but
sloped like a cone in order to enable the vehicle to move
smoothly on curves & straight tracks.
• On Straight & level surface: Circumference of treads of
inner & outer wheels are equal.
• On curves, problem arises when outer wheel has to
negotiate more distance on the curve as compared to
inner wheels.
20. Coning of Wheels
• Due to action of centrifugal force on a curve, wheels tends
to move out.
• To avoid this, circumference of Tread of outer wheel is
made > inner wheel.
• This helps the outer wheel to travel a longer distance than
the inner wheel.
21. Coning of Wheels
• It helps to keep the vehicle centrally aligned on a
straight & level track.
• Slight irregularities in track do occur as a result of
moving loads & the vagaries of the weather.
Therefore wheels move from side to side &
therefore the vehicles sway.
• Due to Coning of Wheels, this side movement
results in the increase in tread circumference of
one wheel over the other.
22. Advantages of Coning of Wheel
• Controlling differential movement of Front &
Rear Axles (which is caused due to rigidity of frame &
axle) thus acting as a balancing factor (on curves
rear axle has the tendency to move towards inner rail)
• Smooth riding as it help vehicle to negotiate
curves smoothly
• Reduces wear and tear of wheel flanges
• Approx. value of slip for BG is 0.029 m/degree of curve
23. Disadvantages of Coning of Wheel
• Pressure on Hz component of force near the INNER edge
of OUTER rail has a tendency to wear the rail quickly
• Hz component has to turn the rail outwards and hence the
gauge may be widened
• If no base plates are provided, sleepers under the outer
edge of the rail may be damaged
• In order to minimize the above disadvantages, Tilting of
Rails is done
24. Tilting of Rails
• Rails are tilted inwards at an angle of 1 in 20 to reduce wear & tear on
the rails & on the tread of the wheels.
• As the pressure of the wheel acts near the inner edge of the rail, there
is heavy wear & tear of the rail.
• Lateral bending stresses are created due to eccentric loading of rails.
• Uneven loading on sleepers damages them
• To reduce wear & tear and lateral stresses, rails are tilted at a slope of
1 in 20 (which is slope of wheel cone)
• Rail is tilted by ADZING the wooden sleepers or by providing canted
bearing plates.
25. Tilting of Rails
• Tilting of rails can be achieved by:
–Adzing of Sleepers
–Use of Canted Base Plate
26. Tilting of Rails
• Advantages of Tilting Of Rails
– It maintains the gauge properly
–Wear at Rail Head is uniform
– It increases the life of sleepers and rails
28. Function of Rails
• It provides a continuous & level surface for
movement of trains
• It provides a smooth & less friction pathway.
– Friction between the steel wheel & steel rail is about
1/5th of friction between pneumatic tyre & metalled road.
• It serves as a lateral guide for the wheels.
29. Function of Rails
• It bear the stresses developed due to vertical
loads transmitted to them
– through axles & wheels of rolling stock as well as
– due to braking & thermal forces.
• It transmits the load to a large area of the
formation through sleepers & the ballast.
30. Requirement of Rails
• Rail should have the most economical
section consistent with – Strength, Stiffness
& Durability.
• Centre of Gravity of rail section should
preferably be very close to the mid-height of
the rail so that the maximum tensile &
compressive stresses are equal.
31. Requirement of Rails
• Rail head: adequate DEPTH to allow for vertical
wear.
• Rail head: sufficiently WIDE so that it has a wider
running surface available & also has desired
lateral stiffness.
• Rail Web: sufficiently thick to withstand stresses
arising due to loads bone by it, after allowing for
normal corrosion.
32. Requirement of Rails
• Rail Foot: sufficient THICKNESS to withstand VR
& Hz forces after allowing for loss of corrosion.
• Fishing angle must ensure proper transmission
of loads from the rails to the fish plates.
• Rail Height: adequate so that rail has sufficient
vertical stiffness & strength as a beam.
34. Function of Sleepers
• Holds rails in their correct gauge &
alignment.
• Giving rails a firm & even support
• Transfers the load evenly from the rails to a
wider area of the ballast.
35. Function of Sleepers
• Acts as an elastic medium between rails &
ballast to absorb blows & vibrations caused
by moving loads
• Providing longitudinal & lateral stability to
the permanent way.
• Providing the means to rectify the track
geometry during their service life.
36. Requirement of Sleepers
• Initial & Maintenance cost: MINIMUM
• Weight: moderate so that it is convenient to
handle.
• Design of the sleeper & fastening should be such
that it is possible to fix & remove the rails easily.
• Sleeper should have sufficient bearing area so
that the ballast under it is not crushed.
• Sleeper should be able to maintain & adjust the
gauge properly.
37. Requirement of Sleepers
• Material of sleeper & its design should be such that it does
not break or get damaged during packing.
• Design of sleeper should be such that it is possible to have
track circuiting.
• Sleeper should be capable of resisting vibrations & shocks
caused by the passage of fast moving trains.
• Sleeper should be anti-sabotage & anti-theft features.
39. Function of Ballast
• Provides a level & hard bed for sleepers to rest on.
• Holds the sleepers in position during the passage of trains.
• Transfers & distributes load from sleepers to a larger area of the
formation.
• Provides elasticity & resilience to the track for proper riding
comfort.
• Provides resistance to the track for longitudinal & lateral stability.
• Provides effective drainage to the track.
• Maintains the level & alignment of the track.
40. Requirement of Ballast
• Tough & wear resistant
• HARD: not get crushed under the moving loads.
• SHAPE: generally cubical with sharp edges.
• Non-porous & should not absorb water.
41. Requirement of Ballast
• Resist both attrition & abrasion.
• Durable & should not get pulverised or
disintegrated under adverse weather conditions.
• Allow for good drainage.
• Cheap & economical.
43. Creep in Rails
• It is defined as the longitudinal movement of rails
wrt sleepers in a track.
• Causes of creep:
– Closing of successive expansion spaces at rail joints in
the direction of creep and opening out of joints at the
point from where the creep starts.
– Marks on flanges and webs of rails made by scratching
as the rails slide.
44. Effects of Creep
• Sleepers move out of position leading to change in gauge
and alignment of the track.
• Rail joints are opened out of their limit & stresses are
developed in fish plates and bolts which leads to the
breakage of the bolts.
• Points and crossings get disturbed.
• Maintenance and replacement of tracks becomes difficult.
• Smashing of fish plates and bolts, bending of bars, kinks
at joints are other effects of creep.
45. Minor Causes of creep in rail
• Rails not properly fixed to sleepers
• Bad drainage of ballast
• Bad quality of sleepers used
• Improper consolidation of formation bed
• Gauge fixed too tight or too slack
• Rails fixed too tight to carry the traffic
• Incorrect adjustment of super elevation on outer rails at
curves
• Incorrect allowance for rails expansion
• Rail joints maintained in bad condition
46. Theories of Creep
• Wave Motion Theory
• Percussion Theory
• Drag Theory
48. Radius or Degree of Curve
• A curve is defined by its – RADIUS or DEGREE.
• Degree of Curve (D) is the angle subtended by a
30.5m or 100ft CHORD at its centre.
• D = 1750/R (R in m)
• D = 5730/R (R in ft)
49. Relationship between Radius & Versine of Curve
• Versine is the perpendicular distance of the midpoint of a
chord from the arc of a circle.
• V = C*C/8R
• V = 12.5 C*C/R cm = 125 C*C/R mm
Degree of Curve with chord length of 11.8m or 62 ft
• D = 1750/R (put value of R=12.5 C*C/V)
• D = V cm
50. Elements of Circular Curve
• Angle of deflection + Angle of Intersection = 180o
• Tangent Length, OT1 = OT2 = R tan o/2
• Length of Long Chord = T1T2 = 2R Sin o/2
• Length of Curve = 2 pi R 00/360
51. Super elevation
• Super elevation or Cant (Ca): is the difference in height
between the OUTER & INNER rail of the curve.
• It is provided by gradually lifting the outer rail above the
level of the inner rail.
• Functions
– To ensure a better distribution of load on both rails.
– To reduce wear & tear of the rails & rolling stock
– To neutralize the effect of lateral forces
– To provide comfort to passengers.
52. Super elevation
• Equilibrium Speed: When speed of a vehicle negotiating a
curved track is such that the resultant force of WEIGHT of
vehicle & RADIAL acceleration is perpendicular to the plane
of rails, the vehicle is not subjected to any unbalanced radial
acceleration & is said to be in equilibrium.
• Maximum Permissible Speed: is the highest speed
permitted to a train on a curve taking into consideration –
Radius of Curvature, Actual Cant, Cant Deficiency, Cant
Excess & Length of Transition.
53. Super elevation
• Cant Deficiency (Cd): It occurs when a train travels
around a curve at a HIGHER than equilibrium
speed. It is the difference between the theoretical
cant required for such HIGH speeds & actual cant
provided.
• Cant Excess (Ce): It occurs when a train travels
around a curve at a LOWER than equilibrium
speed. It is the difference between the actual cant
provided & theoretical cant required for such LOW
speeds.
54. Super elevation
• Rate of Change of Cant or Cant Deficiency
– It is the rate at which cant deficiency increases
while passing over the transition curve, e.g., a
rate of 35mm/sec means that a vehicle will
experience a change in cant or cant deficiency of
35 mm in each sec of travel over the transition
when traveling at maximum permissible speed.
55. Super elevation
• Cant Gradient & Cant Deficiency Gradient
– It indicates increase or decrease in cant or
deficiency of cant in a given length of transition.
– A gradient of 1 in 1000 means a cant or a
deficiency of cant of 1mm is attained or lost in
every 1000mm of transition length.
56. Safe Speed on Curves
• Safe speed means a speed which protects a
carriage from the danger of overturning &
derailment & provides a certain margin of safety.
• For BG & MG
– Transitioned Curves, V1 = 4.4 (R – 70)1/2
– Non-transitioned Curves, V2 = 80% of V1
• V = 0.27 [(Ca + Cd) R]1/2
57. Transition Curve
• A TC smoothen the shift from straight line to the
curve.
• They are provided on either side of the circular
curve so that centrifugal force is built up gradually
as super elevation slowly runs out at a uniform
rate.
58. Transition Curve
• It decrease the radius of curvature gradually in a
planned way from infinity at straight line to
specified value of the radius of a circular curve in
order to help the vehicle negotiate the curve
smoothly.
• It helps in providing the gradual increase of the
super elevation starting from zero at straight line
to the desired super-elevation at the circular
curve.
59. Check Rail
• These are provided parallel to the inner rail on sharp curves
to reduce the lateral wear on the outer rail.
• They prevent the outer wheel flange from mounting the outer
rail & thus decrease the chances of derailment of vehicles.
• CR wear out quite fast but since, these are worn out rails,
further wear is objectionable.
• CR are provided on the gauge face side of inner rails on
curves sharper than 8 degree on BG, 10 Degree on MG & 14
degree on NG.
60. GRADIENTS
• These are provided to negotiate rise or fall in the level of
the railway track.
• In RISING gradient, track rises in the direction of
movement of traffic.
• In DOWN/FALLING gradient, track loses elevation in the
direction of movement of traffic.
• It is represented by the distance travelled for a a rise or fall
of 1 unit. Sometimes it is represented as % rise or fall.
• For e.g., if there is rise of 1m in 400m, the gradient is 1 in
400 or 0.25%.
61. Objective of Gradients
• To reach various stations at different
elevations
• To follow the natural contours of the ground
to the extent possible
• To reduce the cost of earthwork.
62. Types of Gradients
• Ruling G
• Pusher of Helper G
• Momentum G
• G in Station Yards
63. Ruling Gradients
• It is the steepest gradient that exists in a section.
• It determines the maximum load that can be hauled by a
locomotive on that section.
• Factors for deciding the RG
– Severity of G
– Length & position wrt G on both sides.
– Power of locomotive
• In Plain terrain: 1 in 150 to 1 in 250
• In Hilly Terrain: 1 in 100 to 1 in 150
• All other G in that section should be flatter than the RG.
64. Pusher of Helper Gradient
• When the gradient of ensuing section (in
hilly terrain) is so steep as to necessitate
the use of an extra engine for pushing the
train, it is known as P/H G.
• Here gradients steeper than RG are
provided to reduce the overall cost (length
of railway line).
65. Momentum Gradient
• MG is also steeper than RG.
• In valleys, a falling gradient is followed by a
rising gradient.
• During falling G, train gathers good speed or
momentum which gives additional kinetic
energy to the train & allows it to negotiate G
steeper than RG.
66. Gradient in Station Yards
• These are quite flat due to following reasons:
– It prevents the standing vehicles from rolling & moving
away from the yard due to combined effect of gravity &
strong winds.
– It reduces the additional resistive forces required to
start a locomotive.
– Max G: 1 in 400; Recommended G: 1 in 1000
67. Grade Compensation on Curves
• Curves provide extra resistance to movement of
trains.
• Hence, G are compensated to the following extent
on curves:
– On BG tracks: 0.04% per degree of curve or 70/R;
whichever is Minimum.
• G of a curved portion of section should be flatter
than RG because of extra resistance offered by the
curve.
