RAIL & JOINT
Indian railway → 19 Zones and 70 Division
Rail → Designation by weight per unit/meter length
Rail max wear at Sharp Curve
To prevent percolation of water into formation, moorum is used as a blanket for Black cotton soil.
Better ends → Due to slipping of the wheels
Semi-supported joints are used by indian railway
Track modulus = Load per unit length of rail to produce unit deformation or depression in the track
Ballast & Cutting = 1.5:1, Coning = 1:20, Embankment= 2:1.
Railway board for Trunk routes, for BG design V = 160km/hr & max permissible V = 120Km/hr
1st train → Bombay-Thane (1853)
RDSO → Research designs and Standards organisation → Research and development wing of Indian Railway
Item rate contract → Followed by railway department for construction purpose
Manganese steel is used in mfd of metro and monorails
Loading Gauge → Represent max width & height to which a rolling stock (locomotive, coach & wagon) can build.
Buckling of Rails → Misalignment of rail due to temperature changes, due to excessive tightening of bolts, Welded rails on weak tracks, insufficient expansion gaps, Deficiency in Ballast, Excessive creep, jammed joints, Sunken portion in a welded track.
Crushed head → Due to slipping & sliding of rails
Composition of steel used for rail → Carbon and manganese
Track capacity → Trains per hour
Pandrol clips → Used in ballastless tracks
More gauge width recommended → To attain greater speed
A welded rail joint is generally suspended
Choice of gauge → Depends on Traffic volume, Speed of train, Cost of track
Formation width of Railway → The top width of a rail track embankment or bottom width of cutting excluding the side drains
Staggered rail joints → Provided on curves
Requirements of Rails
Min Tensile strength = 72 kg/m² = 700 Mpa
Types of rail
Bull headed rail → Head larger than Foot, provided on Point and crossing
Double headed rail →
Flat footed rail → Top width = 66.7mm, Bottom width = 136.5mm, Used now-a-days in india
Chair → Used to hold double headed and Bull headed rails in position, made up of cast iron
Coning of wheels
Wheels are given an outward slope → 1 in 20
Top of rails of a track → at an inward slope of 1 in 20
↓es wear, tear, rubbing, prevent from slipping
Method of Canting/Tilting
Adzing of sleepers/tilting of rails → Eff use of coning, rails slope = 1:20
Use of Canted Base Plates
Adzing → To provide cant in rails, wooden sleepers are cut to a slope(1:20) at rail seat
Test on rail
To determine serviceability of rail section
Falling weight or tup test, Tensile strength test, Hammer test
Compulsory test → Falling weight test, Tensile strength test
Gauge
Distance b/w inner/running face of two track rail
Light/Feeder/feather track Gauge → Width = 0.610m
The section of Railways decided on the basis of gauge of track
Max ht of rolling stock for BG = 4.14 m
52kg rails are mostly used in BG
Std min crossing clearance for BG = 44 mm
Heel clearance for BG = 11.7 - 13.3 cm
Speed of locomotive in BG = 96 - 120 km/hr
GEOMETRIC DESIGN
Railway board for Trunk Route → Design speed for new route 160 kph, Max permissible speed = 120 kph.
minimum gradient provided on the station yard to drain out off water = 1 : 1000
Ruling Gradient → Max gradient & .. engine can haul the load with its max capacity
Pusher Gradient → Where pusher or helper engine is provided at the end of the train, Most severe gradient
Max allowable grade → Railway < Highway → Steel Wheel on steel rails have lower friction coefficient than rubber tyre on payments
Limit value of cant gradient for all gauge is → 1 in 720
Coefficient of friction of rail surface in a very wet condition = 0.25
Ruling gradient with one locomotive
in plane area → 1 in 150 to 1 in 250
in hilly area → 1 in 100 to 1 in 150
Gradient in station yards
Max = 1 in 400
Min = 1 in 1000 → For easy drainage of rainwater
Grade compensation
BG = 0.04% of degree of curve or 70/R → Minimum of these two
MG = 0.03% of degree of curve or 52.5/R
NG = 0.02% of degree of curve or 35/R
Grade provided = Ruling Grade - Grade compensation
To compensate loss of tractive force → GC = 75/R
Degree of Curve
30.48 or 30.50 m → D = 1750/R
30m chain → D = 1720/R
20m chain → D = 1150/R
Widening of Gauge → Degree of curve > 4½°
D < 3° → Are laid without bending at the curve
Min radius of vertical curves for group A, BG track = 4,000 m
Martin's Formula for Safe Speed on curve
Case - I → Normal Speed (V ≤ 50kph)
i) Provided with Transition curve
Vsafe=4.35R-67 =4.4R-70 → BG
Vsafe=3.65R-6 → NG
ii) Non-Transition Curve
Vsafe= 80% of above
Vsafe=3.48R-67 =3.50R-70 → BG
Vsafe=2.92R-6 → NG
Case - II → High Speed (V > 50 )
Vsafe=4.58R → BG
Indian railway formula (Max Speed)
Based on actual can't(ea) provided & can't deficiency(ed)
Vmax= 127/G (ea+ed)R
Vmax= 0.27 (ea+ed)R → BG
Vmax= 0.34 (ea+ed)R → MG
Vmax= 3.65 R-6 → NG
V = kmph, R = meters, G = Gauge width, ea & ed = in mm
German formula for speed
Speed factor = V²/30000 → V ≤ 100 kmph
Speed factor = 4.5V²/10⁵ - 1.5V³/10⁷ → V > 100 kmph
Super elevation or Cant or Equilibrium e
e=GV2/ 127R=Gv2/gR = Cant
R = 1720/D
e = meters, G = Gauge length, V = Avg velocity(km/h), v = m/sec, R = Radius(m), D = Degree of curve
BG = 1.315V²/R
SG = 1.130V²/R
MG = 0.80V²/R
NG = 0.60V²/R
limiting value of e → BG = 16.5 cm
Limiting value of cant = 1/10 th of Gauge length
No superelevation → Train will give thrust on the outer rail
Cant deficiency
Deficiency in superelevation to maintain average speed
Cant deficiency occurs when a vehicle travel around a curve at higher speed
Cd=eth-eactual=(V2max-V2avg)G /127R
BG = = 7.5 cm (V < 100), = 10 cm (V > 100kmph)
MG = 5.0 cm
NG = 4.0 cm
Rate of change of can't deficiency → MG = 35 mm/sec
Cant deficiency becomes inevitable consideration on a main line and branch line moving in opposite direction
Transition Curve
Highway → Spiral curve
Indian Railway → Froude's cubic Parabola
Eqn of deflection → y = x³/6RL
Shift → s = L²/24R
Versine → h = L²/8R
Spiral Angle → ф = L/2R = 3α
Total angle of deflection → α = L/6R = ф/3
Colour of set from the junction of transition curve and circular curve to the tangent = 1/2 of Shift
Length of transition curve
Railway code → L=4.4R
L = 0.073 e Vmax
Martins formula → Vmax = 4.35R-67
Curvature adopted
BG = 10°
MG = 16°
NG = 40°
SLEEPER & FASTENERS
Sleeper
Usually manufactured with Pre-tensioning
Cement used → 53-S → OPC strength of 53MPa
Function of Sleepers
transverse member supporting rail
Holding the rails in correct gauge & alignment
giving a firm & even support to the rails
Transferring the load evenly from the rails to a wider area of the ballast
Longitudinal & lateral stability to the permanent way
Requirements of sleeper
Should have anti-sabotage & anti-theft features
initial & maintenance cost should be minimum
moderate weight or convenient to handle
Types of Sleeper
Wooden → Provide best elasticity of track, most ideal sleeper, best for track circuiting, but life = 12 - 15 years only, Sal and teak most common
Two-Block Concrete Sleeper → mfd in mould & reinforcement, Tie bars are provided
Composite Sleeper index
To determine the suitability or mechanical strength of a particular timber to use as a sleeper
Min value of CSI → Track sleepers = 783, Crossing slee per = 1352, Wooden sleepers = 1455
CSI = (S + 10H)/20
S = strength index of timber at 12 % moisture content
H = Hardness index of timber at 12 % moisture content
Sleeper density
Number of sleeper per rail length
SD = N + x → N + 3 to N + 7
N = Rail length, x = 3 - 7
BG → N = 13m, SD = N + 5 = 18 Sleepers per rail
MG → N = 12m
No. of sleeper = [(N + x)/N] x Length of rail track in metre
Factor affecting SD → Axle load the rail track is designed to carry, The nature of sleeper and The materials used, lateral thrust of locomotives
Track Fasteners
To hold rails in proper position, To join rail with sleeper, To join adjacent rail
Fish plate
To Join or hold two rails together in both the Horizontal & Vertical Plane → one rail to next
Continuity of rails are maintained by fish plate
Function → Resist heavy transverse shear, Allows thermal expansion & contraction, Maintain correct alignment & continuity of rails
Per fish plate → No of bolts = 4
No of fish plate = 2 x no of joints on track
Fish bolts → Made of high Carbon Steel
BALLAST & TRACK ALIGNMENT
Best ballast stone size = 2 - 5 cm
Track is elastic mainly because of ballast
Purpose → Provide elastic bed, foundation of rail track, Drainage
Ballast materials → Stone aggregate, gravel, moorum, brick aggregate, ash, sand
Sand maybe used as a ballast for cast-iron sleeper
Boxing → relative loose ballast which is placed on the side of the sleeper to provide Lateral Stability
Screening → Renewing ballast
Packing → Compact ballast cushion below sleeper
Ballast Crib → Loose ballast b/w two adjacent sleepers
Max size of ballast → Points and crossing = 25mm, Metal sleeper = 40 mm, Wooden sleeper = 50 mm
For inspection and packing of ballast, each pot sleeper is provided with two holes
Min Depth of ballast layer
D = (S - W)/2 = 1/2 of clear dist b/w consecutive sleeper
S → Sleeper spacing, W → Sleeper width
D → BG = 20 - 25 cm, MG = 15 - 20 cm, NG = 15 cm
Alignment: Topography
Plaint Alignment: Topography is plan & flat.
Zig-zag A : a slope with deep valleys
Cross Country: Sags & summits in succession
Switch back development: One steep regular Slope
Valley alignment: one slope of valley
TRACK STRESSES & CREEP
Resistance provided by the Rails (R) = E𝝰ΔTA
Weight of locomotive axle load = 510 x Weight of rail → WL =510WR
Hauling Capacity = μ W = μwn
Track resistance → Due to wave action of rail
Wear of rail is max → in sharp curve
Racking force on a steel railway bridge → Lateral moment of the train when moving on a straight track
Fillet in a rail section is provided → To avoid stress concentration
Wear of rails may be reduced → By decreasing the number of rail joints
Resistance due to Curve
BG = 0.0004 W D
MG = 0.0003 W D
NG = 0.0002 W D
W = train wt.(tonne), D = degree of Curve
Moving train
For smooth movement of trains → Hauling Capacity > Sum of various train resistance
Tractive Resistance > Hauling Capacity > Total resistance
For numerical problems → Tractive Resistance = Hauling Capacity = Total resistance
Impact factor or coeff of dynamic augment
i=[0.15+8/(6+L)] ≯ 1.0
L = Span of steel girder
Creep in rail
Longitudinal movement of rail with respect to sleeper in track
Checked → Anchors
Permitted creep ≤ 150mm
No creep should be permitted on point & crossing
To prevent creep in rails, Steel sleepers are fixed with rail by clips, bolts and four keys
Creep theory → Wave action theory, drag theory, percussion theory
Measurement → in 3 months interval, BGmax = 150 mm creep
Cause → Rails not secured properly to sleepers, inadequate blast resistance, badly maintained rail joints, improper expansion gap, lake of proper drainage, loose/uneven packing
Effect → Buckling of track, disturb Gauge and alignment of track, point and crossing gets distorted, The blast is forced out of place, joints get jammed and prevent expansion of rail, the ride becomes bumpy and uncomfortable
If double lines are provided separately for up and down traffic → Creep will be more
Prevention of creep
Steel sleepers are fixed with rails by four anchor keys to prevent creep in rails
Using steel sleepers for good grip.
Using Anchors below the rail.
Providing sufficient crib ballast & anchors.
Pulling back rails to original position.
By increasing the number of sleepers per rail length.
Factor affecting creep of the rail
Alignment of track → Observed greater on curves than tangent railway track
More creep in the direction of heaviest traffic
Type of rails → Old rail > New rail
Grade of track → More creep in Downwards steep Gradients
SIGNALS & CONTROL
Absolute block system or space interval system is extensively used in india
Automatic block system → There are arrangements to display stop signals automatically in advance and also to bring the train to a stop
Track circuiting → indicates presence of train on track
Traffic signal at intersections → Reduces right angled collisions but may increase rear end collision
Tradel bar → used for interlocking point and signal
Classification of signals
Home signal also act as routing signal
Crossing stations → Do not have any signal
Disc signal → Purpose of shunting
i. Operational
Audible → Detonating,
Visual signal → Hand, Fixed
ii. Functional
Stop/Semaphore, warner, Shunting, Coloured light signal
Shunting signal → Ground signal, Red band inclined at 45° it indicates Proceed cautiously
Semaphore signal → Ht above ground = 7.5 meters, used when maintenance or repair work is more than 3 days
When Semaphore and warner signals are installed on the same post, than the stop indication is given → When both the arms are horizontal
iii. Locational
Reception → Outer and Starter
Departure → Starter, Advance starter signal
iv. Special signals.
Calling on, Routing, point indicator, Repeater/co-acting
Catenary
In electricity railway line catenary height above rail top = 5.70 meters
RAILWAY STATION & YARD
Junction station → Track line meets a main line
Station Yards
Minimum gradient = 1 in 1000
Passenger Yard
Includes the passenger platforms.
Idle train can be accommodated, examined & cleaned
Locomotives Yard
Houses the locomotive
Facilities like Coaling, Watering, Fueling, Repairing of locomotives.
Goods Yard
Platform useful for Loading & unloading goods
Marshalling Yard
Reception, Sorting & Departure of train
Wagons are received, sorted and new trains are formed
Flat yards → Space limited
Gravitational yards → Ground is sloppy
Hump yard → Pushed against hump
POINTING & CROSSING
Traverser → To transfer the Wagons passenger coaches or locomotive from parallel tracks without any shunting
Turntable/wheelhouse → Reversing direction of Engine or to rotate the engine through 180 degree to change its direction
Overall Depth of dog spike is 120.6 mm
Treadle bar → Used for interlocking points & signals
Acute or skew junctions → All paned type, slip round type, island type
CROSSING
Lead of crossing → Distance Heel of switch to the theoretical nose of crossing
Theoretical Nose of Crossing → Point of intersection of gauge face & Splice Rail
Actual nose of Crossing → Ends of point rail
Double/Scissor Crossover → 4 pair points, 6 acute angle crossing & 2 obtuse angle crossing
Scissor crossover b/w two parallel railway tracks contains a diamond crossover
Diamond crossing → When two tracks of same or different gauges cross each other at any angle
Level crossing → Railway line and a road cross each other at the same level
L = CL - SL
L → Lead of crossing, CL → Curve lead, SL → Switch lead
Methods for crossing angle → Right angle method, Centre line method, isosceles triangle method
TURNOUT
Divert train from one track to another track
Points + Crossing + Lead rail
Overall length → Distance b/w end of stock-rail and throat of crossing
Component of turnout
Switches/ 2 points, Stock rail one pair, V crossing/an acute angle crossing, Check rail pair, 4 lead rails
Stock rail → The fixed rail in a railway track against which the tongue rail fits
Wing Rail → To guide the wheel path for movement of the train
Check rail
Function → Protection from derailment, Protection for flange from excessive wear, Protection from excessive wear of rail
Provided inner side → Curve sharper than 8° for BG, 10° for MG, 14° for NG
Dist b/w inner and check rail on sharp curve = 44mm
SWITCH
A pair of tongues with stock rail with connection
Points → Group of Switches
i. Heel Clearance or Divergence
Distance b/w Gauge Running faces of the stock rail & the tongue rail at the heel of the switch
Heel clearance > Flangeway clearance
For BG = 13.7 - 13.9m
ii. Flangeway Depth
Vertical distance b/w top of rail to heel back
iii. Flangeway Clearance
Distance b/w Adjacent faces of the stock rail & the tongue rail at the heel of the switch
iv.Tongue Rail
Tapered moveable rail
Toe of switch → Movable tapered end of the tongue rail
Throw of Switch → max distance by which Toe of tongue rail moves Sideway, for BG = 9.5cm, MG = 8.9cm, NG = 8.9cm
v. Switch Angle
Angle b/w running faces of tongue rail & stock rails when tongue rail touches stock rail
= sin-1(d/D)
α = Heel Divergence/Length of tongue rail
Depends on → heel divergence and length of tongue rail
Siding
Branch line from the main line or a loop line terminates at a dead end with a buffer stop
Catch siding → Siding provided on steep slopes so that a wagon at rest will not enter the main line
TOOLS & USE
Auger : drill holes for spikes
Chisel : Cut the Rails & Bolts
Wire Claw : Clean & spread ballast
Shovel → Handle ballast
Jim crow → Bend the rails
Rail tongue → lift & carry Rail
Claw bar → Remove dog spikes from sleepers
Crow bars →To correct track alignment → raise sleeper to desired ht & replacement of track
Tradel bar →for interlocking points & signals
Lock bar → Provided so point may not be operated while train is on it
Realignment of straight track is done by using crowbar & track liners.
Maintenance cost : Roads > Railways.
Operation cost : Roads < Railways.
Disc Signal : for Shunting.
Slip circle method is used to determine the Stability of the formation Slope railway line.
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