By

Rajeev Roushan

CI/C&W/IRIMEE

Failure due to formationFailure due to formation..

The formation is affected by following factors:The formation is affected by following factors: Sudden subsidence of embankmentSudden subsidence of embankment Base failureBase failure Ballast puncturing due to heavy rains etc.Ballast puncturing due to heavy rains etc. MuddinessMuddiness

The inadequate care taken in maintaining the The inadequate care taken in maintaining the formation may cause derailments as failure of formation may cause derailments as failure of formation results in disturbance of track formation results in disturbance of track geometrygeometry

Failure of formationFailure of formation

Failure of ballastFailure of ballast

It absorbs noise, shocks, vibrations and It absorbs noise, shocks, vibrations and distributes the load transmitted by the wheels distributes the load transmitted by the wheels over the formation.over the formation.

controls the lateral and longitudinal movement controls the lateral and longitudinal movement of track.of track.

It keeps the track in position and at required It keeps the track in position and at required level. level.

If sufficient quantity of ballast is not available, If sufficient quantity of ballast is not available, track may get distorted andtrack may get distorted andor buckled.or buckled.

BallastBallast

Cushion Ballast - 300 mm.Cushion Ballast - 300 mm. Shoulder ballast - 400 mm in F/ Shoulder ballast - 400 mm in F/

Plated track & SWR , 350 mm on straight and Plated track & SWR , 350 mm on straight and inside of curve of LWR and 500 mm on inside of curve of LWR and 500 mm on outside of curve of LWR.outside of curve of LWR.

Failure of sleepersFailure of sleepers

It must be laid at right angle to the rail. It must be laid at right angle to the rail. When the sleepers are damaged to an extent When the sleepers are damaged to an extent

that they cannot hold the gauge, the rails get that they cannot hold the gauge, the rails get tilted in both the seats, the gauge get widened tilted in both the seats, the gauge get widened and both the wheels drop inside the track.and both the wheels drop inside the track.

Traffic DensityGMT/yr

Broad-gauge Routes and their Rail Weights

A B C D Spl D E Spl E

> 20 60kg 60kg 60kg 60kg 60kg 60kg 60kg

10-20 60kg 60kg 60kg 60kg 60kg 60kg52kg 90UTS

5-10 60kg52kg 90UTS

52kg 90UTS

52kg 90UTS

52kg 90UTS

52kg 90UTS

52kg 90UTS

< 552kg 90UTS

52kg 90UTS

52kg 90UTS

52kg 90UTSor 60kg SH

52kg 90UTSor 60kg SH

52kg 90UTSor 60kg SH

52kg 90UTSor 60kg SH

Loop Lines 52kg SH 52kg SH 52kg SH 52kg SH 52kg SH 52kg SH 52kg SH

'SH' = Second-hand

Traffic DensityGMT/yr

Broad-gauge Routes and their Sleeper Densities

A B C D Spl D E Spl E

> 20 1660 1660 1660 1660 1660 1660 1660

10-20 1660 1660 1660 1660 1660 1660 1540

< 10 1660 1540 1540 1540 1540 1540 1540

Loop Lines 1340 1340 1340 1340 1340 1340 1340

Failures of railsFailures of rails The wear on rails play a vital role in increasing The wear on rails play a vital role in increasing

the mounting tendency of wheel on the rail table. the mounting tendency of wheel on the rail table. The excessive wear may even result in rail The excessive wear may even result in rail fracture which may cause fracture which may cause Derailment.Derailment.

Types of rail wear – (i) Vertical wearTypes of rail wear – (i) Vertical wear (ii) Lateral wear(ii) Lateral wear (iii) Angular wear(iii) Angular wear

Rail Wear Rail Wear

Vertical wearVertical wear Rail sectionRail section LimitLimit 60 kg 13mm 60 kg 13mm 52kg 8mm52kg 8mm 90R 5mm90R 5mm It vertical wear is excessive , a deep flange may It vertical wear is excessive , a deep flange may

ride over fish plate/distance block/ check block ride over fish plate/distance block/ check block and may damage the track components. Measure and may damage the track components. Measure the rail height at the centre of rail.the rail height at the centre of rail.

Lateral wearLateral wear SectionSection Category of trackCategory of track LimitLimit Curves A & B 8mm Curves A & B 8mm C & D 10mmC & D 10mm Straight A & B 6mmStraight A & B 6mm C &D 8mmC &D 8mm It should be measured 13mm below the top surface It should be measured 13mm below the top surface

of the rail.of the rail. Excessive lateral wear increases the play between Excessive lateral wear increases the play between

the wheel set and track which would contribute to the wheel set and track which would contribute to increased oscillations and greater angularity of increased oscillations and greater angularity of flange during run. flange during run.

Angular wearAngular wear The maximum angular wear permitted as 25The maximum angular wear permitted as 250 0 on all on all

tracks. If angular wear is excessive, the rail presents an tracks. If angular wear is excessive, the rail presents an inclined plane to the wheel on which the flange may inclined plane to the wheel on which the flange may slide upwards.slide upwards.

Other defects – Other defects – 1.Battering1.Battering 2.Hogging2.Hogging 3. Scabbing3. Scabbing 4. Wheel burn4. Wheel burn 5.Rail fracture 5.Rail fracture

Gauge VariationGauge Variation Causes of gauge distortionCauses of gauge distortion – – (1) Worn out fastenings due to which track could not (1) Worn out fastenings due to which track could not

hold the correct gauge.hold the correct gauge. (2) damaged sleepers and unserviceable sleepers due to (2) damaged sleepers and unserviceable sleepers due to

which fastening become loose.which fastening become loose. (3)fastening not properly secured and becoming loose (3)fastening not properly secured and becoming loose

due to high speed variations.due to high speed variations. (4)missing fastenings i.e. keys, spikes, pandrpl clip. (4)missing fastenings i.e. keys, spikes, pandrpl clip.

Effect of slack gaugeEffect of slack gauge – – Due to slack gauge, play Due to slack gauge, play between flange and running edge of the rail between flange and running edge of the rail increases , which increases lateral oscillations, increases , which increases lateral oscillations, hunting, excessive flange forces due to which hunting, excessive flange forces due to which the wheel may drop.the wheel may drop.

Effect of tight gaugeEffect of tight gauge – tight gauge increases – tight gauge increases strain on track fastenings and creates a tendency strain on track fastenings and creates a tendency for the wheel to lift on run. Due to this, flange for the wheel to lift on run. Due to this, flange starts grinding against the rail edge, it causes starts grinding against the rail edge, it causes high flange forces to occur and the flange high flange forces to occur and the flange ultimately mounts over the rail.ultimately mounts over the rail.

Permissible gauge tolerancesPermissible gauge tolerances

On straight -3mm(tight) +6mm(slack)On straight -3mm(tight) +6mm(slack) On Curve more than 400m RadiusOn Curve more than 400m Radius -3mm(tight) +15mm(slack)-3mm(tight) +15mm(slack) On Curve less than 400m RadiusOn Curve less than 400m Radius Nil (tight) +20mm (slack)Nil (tight) +20mm (slack) Gauge is measured by Level cum gauge.Gauge is measured by Level cum gauge. Gauge is measured 14 mm below the rail top Gauge is measured 14 mm below the rail top

table.table.

Cross level defectsCross level defects

The relative difference in the height of left and The relative difference in the height of left and right rail at a given point on the track is known right rail at a given point on the track is known as as cross levelcross level (on straight track). (on straight track).

During maintenance

During service

Cross Level difference

Variation not more than 4

mm

Var. not more than 8 mm.

Twist on 3 metre base

Var. not more than 2

mm/metre

Var. not more than 3 mm/metre

TwistTwist

It may be defined as algebraic difference of It may be defined as algebraic difference of cross level per meter. The effect of twist may cross level per meter. The effect of twist may cause uneven loading of wheels and this cause uneven loading of wheels and this condition is prone to condition is prone to DerailmentDerailment..

Twist for straight and curvesTwist for straight and curves – Variation not – Variation not more thanmore than2mm/meter2mm/meter & & 3mm/meter3mm/meter over over 3meter base 3meter base during maintenanceduring maintenance & & during during serviceservice respectively. respectively.

Permissible standards for twistPermissible standards for twist

Track categoryTrack category Twist in mmTwist in mm A 0 to 5 ( up to 1.39mm/m)A 0 to 5 ( up to 1.39mm/m) B 5 to 7.5 (1.39 -2.08 mm/m)B 5 to 7.5 (1.39 -2.08 mm/m) C 7.5 to 10 (2.08 -2.78 mm/m)C 7.5 to 10 (2.08 -2.78 mm/m) D above 10 (above 2.78 mm/m)D above 10 (above 2.78 mm/m) Above Twist calculation should be measured Above Twist calculation should be measured

on 3.6 m base.on 3.6 m base.

Track alignment and Unevenness defectTrack alignment and Unevenness defect Due to this defects, the springs start oscillating Due to this defects, the springs start oscillating

and continue to off load the left and right wheels and continue to off load the left and right wheels alternatively even after the irregularity is alternatively even after the irregularity is crossed. crossed.

If the natural frequency of the vehicle happens If the natural frequency of the vehicle happens to coincide with the exciting frequency, the to coincide with the exciting frequency, the oscillation can develop dangerous proportions oscillation can develop dangerous proportions causing “derailment”. causing “derailment”.

Tolerances for ATolerances for Alignment & lignment & UnevennessUnevenness

Track categoryTrack category AlignmentAlignment Unevenness Unevenness (7.2 m chord) (7.2 m chord) (3.6 m chord) (3.6 m chord)

A 0 to 3 mm 0 to 6 mmA 0 to 3 mm 0 to 6 mm B 3 to 5 mm 6 to 10 mmB 3 to 5 mm 6 to 10 mm C above 5 mm 10 to15 mm C above 5 mm 10 to15 mm D above 15 mmD above 15 mm

Effect of CreepEffect of Creep There are several serious effects of There are several serious effects of creep, the most serious is creep, the most serious is BucklingBuckling of the track. of the track. Harmful effects are Harmful effects are

(1)The sleepers move out of square and position.(1)The sleepers move out of square and position. (2)The gauge and alignment of the track gets distorted.(2)The gauge and alignment of the track gets distorted. (3)Rail joints at the starting points of the creep get (3)Rail joints at the starting points of the creep get

opened out of their permissible limit. The stresses opened out of their permissible limit. The stresses develop in the fish plates and bolts. This may cause develop in the fish plates and bolts. This may cause break the fish bolts and rail ends gets battered badly. break the fish bolts and rail ends gets battered badly. Due to creep, rail joints get jammed.Due to creep, rail joints get jammed.

(4)Points and crossings get disturbed.(4)Points and crossings get disturbed. (5)The expansion gaps become either too big or too (5)The expansion gaps become either too big or too

short.short. Permissible limit of creep is Permissible limit of creep is 150mm. 150mm.

Buckling of trackBuckling of track

Rail track is liable to get distorted particularly during Rail track is liable to get distorted particularly during hot weather when compressive forces in track exceed hot weather when compressive forces in track exceed lateral or longitudinal resistance of track.lateral or longitudinal resistance of track.

Causes of bucklingCauses of buckling – (1) Inadequate resistance to – (1) Inadequate resistance to track due to deficiencies of ballast.track due to deficiencies of ballast.

(2)Ineffective or missing fastenings.(2)Ineffective or missing fastenings. (3)Failure to lubricate SEJs in time.(3)Failure to lubricate SEJs in time. (4)Execessive creep, jammed joints in the track.(4)Execessive creep, jammed joints in the track.

BucklingBuckling

Vulnerable locations where track is prone to Vulnerable locations where track is prone to bucklingbuckling

(1) Approaches of level crossing, bridges and (1) Approaches of level crossing, bridges and yards etc.yards etc.

(2)Junction point of fish plated , SWR and (2)Junction point of fish plated , SWR and LWR track.LWR track.

(3)Location with deficient ballast section (3)Location with deficient ballast section particularly on the shoulders.particularly on the shoulders.

BucklingBuckling

Derailment on curvesDerailment on curves Adverse factors on a curveAdverse factors on a curve – (1)Execessive – (1)Execessive

angular wear on the outer rail.angular wear on the outer rail. (2) Excessive flattening of head on the inner rail.(2) Excessive flattening of head on the inner rail. (3) Fracture and failure of rails.(3) Fracture and failure of rails. (4) Gauge widening and track distortion.(4) Gauge widening and track distortion. (5) Vehicle entering a curve at speeds higher (5) Vehicle entering a curve at speeds higher

than maximum permissible speed may cause than maximum permissible speed may cause distortion of track or lead to mounting of wheel distortion of track or lead to mounting of wheel over the outer rail.over the outer rail.

Effect of less super elevationEffect of less super elevation – Due to less super – Due to less super elevation, there is a possibility of outer rail getting elevation, there is a possibility of outer rail getting worn out as it will have to bear more strain due to worn out as it will have to bear more strain due to tendency of wheels to move away from the center of the tendency of wheels to move away from the center of the curve under the influence of centrifugal forces. curve under the influence of centrifugal forces.

Effect of more super elevationEffect of more super elevation – (1) Inner rail will have – (1) Inner rail will have to bear maximum strain and there is every possibility of to bear maximum strain and there is every possibility of this rail giving way due to excessive strain and cause this rail giving way due to excessive strain and cause gauge widening.gauge widening.

(2)Due to excessive super elevation, there is every (2)Due to excessive super elevation, there is every possibility of slow moving goods trains getting possibility of slow moving goods trains getting derailed.derailed.

Maximum super elevation prescribed –Maximum super elevation prescribed – Track groupTrack group Max. cant in mmMax. cant in mm A,B,C 165A,B,C 165 D,E 140D,E 140 Cant deficiency for normal speed up to 100kmph – Cant deficiency for normal speed up to 100kmph –

75mm & for high speed– 100mm 75mm & for high speed– 100mm Length of transition curve = 0.008CLength of transition curve = 0.008Caa* V* Vmm

=0.008 C=0.008 Cdd* V* Vmm

== 0.72 C0.72 Caa

CCaa=actual cant provided, V=actual cant provided, Vmm=maximum , permissible =maximum , permissible speed, Cspeed, Cd d =Cant deficiency =Cant deficiency

Measurement of versineMeasurement of versine – The versines on curves are – The versines on curves are measured using 20m chords with stations at 10m measured using 20m chords with stations at 10m intervals.intervals.

For Turn-out versines to be measured every 1.5 metres For Turn-out versines to be measured every 1.5 metres with overlapping chord of 6 meters (IRPWM Para. with overlapping chord of 6 meters (IRPWM Para. 401). 401).

Tolerances of versine Tolerances of versine For curve more than 600m radiusFor curve more than 600m radius – – A &B 20mmA &B 20mm C & D 25mmC & D 25mm For curve less than 600m radiusFor curve less than 600m radius – Values of actual – Values of actual

versines not vary 20% of theoretical versines subject versines not vary 20% of theoretical versines subject to a maximum of 55mm.to a maximum of 55mm.

Derailment on Points and CrossingDerailment on Points and Crossing

CauseCause – (1) Derailment occurs on Pts & Xing – (1) Derailment occurs on Pts & Xing at switches (points) which either gape initially at switches (points) which either gape initially or open slightly under the passing wheels. or open slightly under the passing wheels. Gaping points are caused by Gaping points are caused by

(i) bent tongue rail and by wrongly adjusted (i) bent tongue rail and by wrongly adjusted heel boltsheel bolts

(ii) Any obstruction like a piece of stone will (ii) Any obstruction like a piece of stone will also result in the switches not setting home.also result in the switches not setting home.

(2) Very loose heel bolts and badly packed (2) Very loose heel bolts and badly packed sleepers under the heel chairs will permit the sleepers under the heel chairs will permit the of switches to lift under passing wheels. This of switches to lift under passing wheels. This will also prone to derailmentwill also prone to derailment

(3) The head of switch is 5 mm lower than the (3) The head of switch is 5 mm lower than the stock rail at a distance of 450 mm from the stock rail at a distance of 450 mm from the toe. Its thickness at this section is 10 mm. toe. Its thickness at this section is 10 mm. Therefore if the stock rail is worn out by 5 mm Therefore if the stock rail is worn out by 5 mm and the side wear is permitted to proceed too and the side wear is permitted to proceed too far, the crushing of the switch head and far, the crushing of the switch head and resulting flow of metal will prevent the proper resulting flow of metal will prevent the proper setting of the switch. setting of the switch.

(4) Sharp flange is dangerous at Pts & Xing as (4) Sharp flange is dangerous at Pts & Xing as it mounts the rail at points and nose and heel it mounts the rail at points and nose and heel of switch rails and Xing.of switch rails and Xing.

(5) The wheel flange will hit the edge of the (5) The wheel flange will hit the edge of the nose normally at the tip of the flange if the nose normally at the tip of the flange if the gauge is tight by 10 mm or the clearance of the gauge is tight by 10 mm or the clearance of the check rail is 47 + 10 = 57 mm. In this case check rail is 47 + 10 = 57 mm. In this case wheel will certainly mount the nose.wheel will certainly mount the nose.

(6) High wing rail of a crossing may cause a (6) High wing rail of a crossing may cause a derailment in the trailing direction. In trailing derailment in the trailing direction. In trailing direction, the function of wing rail is to direction, the function of wing rail is to progressively relieve the load on the ‘Vee’ of progressively relieve the load on the ‘Vee’ of the crossing. The gradual transfer of the load the crossing. The gradual transfer of the load starts at a point X provided the wing rail starts at a point X provided the wing rail permits the wheel tread to bear on it. It Xing is permits the wheel tread to bear on it. It Xing is worn and the wing rail is new, the tyre may get worn and the wing rail is new, the tyre may get wedged between the two wing rails and force wedged between the two wing rails and force them apart as the axle moves forward. This them apart as the axle moves forward. This will cause derailment.will cause derailment.

Derailment on points & crossingsDerailment on points & crossings

Inspection on Pts.& XingInspection on Pts.& Xing – (1) condition of ballast – (1) condition of ballast and drainage.and drainage.

(2) condition of tongue rails and stock rails.(2) condition of tongue rails and stock rails. (3) condition of fittings of tongue and stock rails.(3) condition of fittings of tongue and stock rails. (4)Gauge and cross level at switch assembly – It (4)Gauge and cross level at switch assembly – It

should be correct at all locations.should be correct at all locations. (a) At stock joint(a) At stock joint (b) 150mm behind the toe of switch(b) 150mm behind the toe of switch (c) At mid switch for straight and for turn out side.(c) At mid switch for straight and for turn out side. (d) At heel of switch for straight and for turn out side.(d) At heel of switch for straight and for turn out side.

(5) Clearance between stock and tongue rails at (5) Clearance between stock and tongue rails at heel of switch or Heel divergence – heel of switch or Heel divergence –

1 in 16 or 1in121 in 16 or 1in12 1 in 8.5 1 in 8.5 133mm 136mm 133mm 136mm (6) Throw of switch – 95 to 115mm.(6) Throw of switch – 95 to 115mm. (7) Conditions of Xing and tongue rail – Check(7) Conditions of Xing and tongue rail – Check (a) maximum vertical wear on point and wing (a) maximum vertical wear on point and wing

rail is 10mm.rail is 10mm. (b) Xing reconditioning should be done when (b) Xing reconditioning should be done when

wear is 6mm.wear is 6mm. (c) maximum vertical wear permitted on (c) maximum vertical wear permitted on

tongue rail is 6mm.tongue rail is 6mm. (d) lateral wear permitted is 8mm for (d) lateral wear permitted is 8mm for

90R,52kg rail.90R,52kg rail.

(8) Gauge and cross level of Xing assembly – (8) Gauge and cross level of Xing assembly – (a)1m ahead of nose on nose on straight and on turn (a)1m ahead of nose on nose on straight and on turn out.out.

(b)150mm behind ANC on straight and on turn (b)150mm behind ANC on straight and on turn out.out.

(c) 1m behind ANC on straight and on turn out. (c) 1m behind ANC on straight and on turn out. All the above measurement should be correct.All the above measurement should be correct. (9) Check rail clearance – 44 (min) to 48mm (max)(9) Check rail clearance – 44 (min) to 48mm (max) (10)Cross level on straight and turn out should be (10)Cross level on straight and turn out should be

correctcorrect

(11) Lead curvature – The curvature should be (11) Lead curvature – The curvature should be checked either by offset method or by versine checked either by offset method or by versine method It should be correct and uniform.method It should be correct and uniform.

(12) Sleepers – It should be well packed, (12) Sleepers – It should be well packed, squaring, and spacing of sleepers should be squaring, and spacing of sleepers should be proper.proper.

The wear of tongue rail shall not exceed the The wear of tongue rail shall not exceed the following limits.following limits.

Vertical wear – 8 mm for 60 kgVertical wear – 8 mm for 60 kg - 5 mm for 52 kg and 90 R- 5 mm for 52 kg and 90 R Lateral wear – 8 mm for 60 kgLateral wear – 8 mm for 60 kg - 6 mm for 52 kg and 90 R- 6 mm for 52 kg and 90 R

Examination of TrackExamination of Track

Normally measurements will be take at Normally measurements will be take at stations three metres apart for a distance of 45 stations three metres apart for a distance of 45 metres on either side of 0 station. They may be metres on either side of 0 station. They may be taken for column Gauge & cross level (3,4,5) taken for column Gauge & cross level (3,4,5) may in addition be a taken individual sleepers may in addition be a taken individual sleepers for a length of 9 metres in the rear of 0 station. for a length of 9 metres in the rear of 0 station. They may be taken for a distance of 90 metres They may be taken for a distance of 90 metres in rear where the cause of derailment is not in rear where the cause of derailment is not obvious.obvious.

Tools which must be available in ART Tools which must be available in ART for taking above measurementsfor taking above measurements

For TrackFor Track – (1) Gauge and level – (1) Gauge and level (2) Stepped feeler gauge set(2) Stepped feeler gauge set (3) Fish chord or nylon wire 10m.(3) Fish chord or nylon wire 10m. (4) Steel scale 30cm.(4) Steel scale 30cm. (5) straight edge 1.5m(5) straight edge 1.5m (6) Measuring tape 20m length (6) Measuring tape 20m length

Measuring EquipmentsMeasuring Equipments Straight edge & Sprit levelStraight edge & Sprit level – To check the alignment – To check the alignment

and cross level.and cross level. Gauge cum LevelGauge cum Level - To Check the gauge and cross - To Check the gauge and cross

level.level. Mallet or wooden hammerMallet or wooden hammer – To check the packing of – To check the packing of

the sleepers .the sleepers . Canne- a- bouleCanne- a- boule - A modern equipment to assess the - A modern equipment to assess the

voids under the sleepers.voids under the sleepers. T-squareT-square – To – To check square ness of sleepers.check square ness of sleepers. Stepped feeler gaugeStepped feeler gauge – To measure the wear or the – To measure the wear or the

clearances. clearances.

Maintenance ToolsMaintenance Tools

Sleeper TongSleeper Tong – To carry the sleepers. – To carry the sleepers. Rail TongRail Tong – To lift and carry the rails. – To lift and carry the rails. BeaterBeater - To pack the ballast under the sleepers - To pack the ballast under the sleepers Crow barCrow bar – To correct the track alignment and to lift – To correct the track alignment and to lift

the track for surfacing; Also to take out dog spikes the track for surfacing; Also to take out dog spikes for which clawed crow bars are usedfor which clawed crow bars are used..

Jim crowJim crow - - To bend the rails or break the railsTo bend the rails or break the rails Spiking hammerSpiking hammer – To drive the spikes. – To drive the spikes. Keying hammerKeying hammer – To drive the keys. – To drive the keys.

Maintenance toolsMaintenance tools

SpannerSpanner – To tighten the bolts. – To tighten the bolts. Wire claw or ballast rakeWire claw or ballast rake – To draw or pull out the – To draw or pull out the

ballast while doing screening, packing etc.ballast while doing screening, packing etc. PhowrahPhowrah – To cut the earth or to pull out ballast. – To cut the earth or to pull out ballast. Auger Auger – To bore the holes in wooden sleepers.– To bore the holes in wooden sleepers. Box spannerBox spanner – For driving home rail screws or plate – For driving home rail screws or plate

screws in the hole.screws in the hole. Wire basketWire basket – For screening the ballast. – For screening the ballast.