rkgoel track

8/13/2019 Rkgoel Track

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2.2.1 The table given above clearly indicates that with the change ofrail section from 90R/52 kg to 60 kg, the maximum permissibleoverall length of girder bridges over which LWR/CWR can becontinued, gets reduced. This aspect therefore, needs to bekept in view while planning Track Renewal works on GirderBridges.

2.2.2 The following stipulations are required to be followed whilelaying LWR/CWR on girder bridges as per above table:

a) Rail free fastenings shall be provided throughout thelength of the bridge between abutments.

b) The approach track upto 50m on both sides shall beanchored by providing any one of the following:

i) ST sleepers with elastic fastening.

ii) PRC sleepers with elastic rail clips with fair T orsimilar type creep anchors.

c) The ballast section of approach track upto 50 metreshall be heaped upto the foot of the rail on the shouldersand kept in well compacted & consolidated conditionduring the of extreme summer and winter.

d) Single span of the bridge shall not exceed 30.5 metresand shall have sliding bearings on both ends.

e) Wherever the girder bridges are provided with rail freefastenings and partly box anchored on each span, 4central sleepers shall be box-anchored with fair V orsimilar type creep anchors and the bridge timbers laidon girders shall be notched to accommodate individualrivets heads instead of through notch.

f) The girders shall be centralized with reference to thelocation strips on the bearing, before laying LWR/CWR.

g) The sliding bearings shall be inspected during themonths of March and October each year and cleared ofall foreign material. Lubrication of the bearings shall bedone once in two years.

2.2.3 Welded rails may be provided from pier to pier with rail freefastenings and with SEJ on each pier. The rail shall be boxanchored on four sleepers at the fixed end of the girder if thegirder is supported on rollers on one side and rockers on other


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side. In case of girders supported on sliding bearings on bothsides, the central portion of welded rails over each span shallbox anchored on four sleepers. On both side of approachesfully creep anchored fastening shall be used. The length ofsingle span bridge permitted temperature zone-wise shall beas under:

TemperatureZone

Maximum length of single span girder bridgewith SEJ (190mm gap) at 30m away fromboth abutments with full creep resistantfastenings at approaches (td = tm)

IVIIIIII

75m87m110m146m

2.2.4 LWR/CWR may also be continued over a girder bridge with theprovisions of SEJ at the far end approach of the bridge usingrail-free fastenings over the girder bridge. The length of thegirder bridge in this case, however, will be restricted by thecapacity of the SEJ to absorb expansion, contraction andcreep, if any, of the rails. The length of the girder bridges withthe above arrangement that can be permitted in various railtemperature zones for LWR/CWR with SEJs having maximummovement of 120 mm and 190 mm are as follows:

Railtemperature zone

Max.movement of SEJused(mm)

Max. length ofbridge with SEJ Initial SEJ gap tobe provided at td

WithST/PRCapproachsleepers

WithCST-9approachsleepers

WithST/PRCapproachsleepers

WithCST-9approachsleepers

IV 190 55 m 45 m 7.0 cm 6.5 cmIII 190 70 m 70 m 7.0 cm 6.5 cmII 190 110 m 100 m 6.5 cm 6.5 cm

I 190 160 m 150 m 6.5 cm 6.0 cmII 120 20 m 15 m 4.0 cm 4.0 cmI 120 50 m 50 m 4.0 cm 4.0 cm

Note : SEJ is to be installed 10 m away from the abutments


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2.2.5 It is evident from the above table that the provisions are samefor 90R/52 kg or 60 kg rail section. However, the LWR/CWRcan be permitted on bridges of longer length if the approachsleepers are changed to ST/PRC instead of CST-9.

2.2.6 Bridge on which LWR/CWR is not permitted/provided shall be

isolated by a minimum length of 36 meters well anchored trackon either side.

2.2.7 The instructions for permitting short welded rail panels ongirder bridges are given in Indian Railways P. Way Manual asunder:

SWR may be continued over girder bridges with un-ballasteddecks up to 13.3m opening if the length of SWR is symmetricalto the centre ling of bridge and up to 6.1m opening if the lengthof SWR is unsymmetrical to the centre line of the bridge. No

fish-plated joint should be located on the girder or within sixmeters from either abutment. In all such cases rail freefastenings, such as rail screws, dog spikes or rail free clipsshall be used, so that relative movement between rail andsleepers may take place.

2.3 SLEEPERS SPACING OF STEEL GIRDER BRIDGE-

In case of bridge timbers the sleepers spacing and depth to befollowed is again given in IRPW manual as under:

Gauge

Clear distancebetween

consecutivesleepers not to

exceed

Depth ofsleepers

(exclusive ofnotching) not

less than

Length of sleepers

B.G. 510 mm 150 mm Outside to outside ofgirder flanges plus 305mm. but not less than2440 mm.

M.G 305 mm 125 mm Outside to outside ofgirder flanges plus 305

mm. but notless than 1675 mm.

N.G. 125 mm 125 mm Outside to outside ofgirder flanges plus 305mm. but not less than1525 mm


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2.3.1 The size of bridge timber also depends on centre to centredistance of girders. For sal wood timbers or other similartimbers the depth of timber is to be kept as under:

B.G. M.G.

Centre to

Centre ofGirder

Depth of

sleeperexcludingnotching

Centre to

Centre ofgirder

Depth of

sleeperexcludingnotching

Up to 1,850Up to 2,000

Up to 2,300

150 mm.180 mm.240 mm.

Up to 1,250Up to 1,650Up to 2,000

150 mm.200 mm.240 mm.

2.3.2 The minimum width of timber is to be kept as 250mm in BGand 200mm in MG.

2.3.3 For standard bridge spans, the size of bridge timbers is to bekept as give below:

Spans in MetersB.G. M.G.

Size of sleeperb x d

Size of sleeperb x d

Up to 12.2 250 x 150mm.

250 x 150 mm.

200 x 150 mm.

200 x 200 mm.

200 x 200 mm.

200 x 240 mm.

Up to 18.3

Up to 24.4 250 x 180 mm.

250 x 240 mm.Up to 30.5

2.3.4 Clear distance between joint sleepers is to be kept less than200mm for BG as well MG.

3.0 TRACK STANDARD FOR BRIDGE APPROACHES

3.1 With a view to eliminate possibility of derailment on the approaches ofmajor/important bridges, it is necessary to strengthen the track in the

approaches of major/important bridges. According, to NorthernRailway CE circular No.221 on P.Way, the following measures are tobe taken for the purpose:

i) PRC sleepers to Drg. No. T-4089 to Drg. No. T-4097 should beprovided under guard rails of all bridges.


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ii) In case of CST9, ST and wooden road on the approaches of thegirder bridges, PRC sleepers should be provided under the guardrails and up to a length of 100 m on the approach with full ballastcushion as laid down. However, in case the approach track isLWR/CWR, the PRC sleepers should be provided only up to theSEJ and the entre breathing length of LWR/CWR should be

provided with box anchoring.

iii) 100% fittings must be ensured at all time on girder bridges both onrunning rail and the guard rail and in approach track up to 100 m/breathing length. Any deficiency noticed must be made goodimmediately.

iv) Buffer rails, wherever, existing in approaches of bridges havingLWR/CWR track, should be replaced with switch expansion joints.

v) Full ballast section of LWR track should be provided up to 100m

from the abutment.

vi) For 1 rail length from abutment, ballast retainers should beprovided to check slipping of ballast and to ensure full ballastsection.

vii) The sleeper spacing on the approaches of bridges up to 100mlength should made 60 cm. However, where it is not immediatelypossible, the existing sleeper spacing may continue but 60 cmsleeper spacing must be provided at the time of renewals/deepscreening works.

viii) Rail level of track in approaches of bridges should be maintainedstrictly as per section and dips in rail level immediately afterabutments must be avoided.

ix) In order to avoid bunching of sleepers over girder (a) guard railsmust have notching at spike locations and (b) tie bars should befixed on outside of sleepers with hook bolts passing through the tiebars.

x) It should be ensured that for a length of about 100m on either sideof the girders bridges, the width of cess available on BG is 90 cmclear of full ballast section.

xi) Wherever curve sharper than 3 degree exist on the approaches ofmajor girder bridges, these should be provided with check rails.

The above stipulations should be followed in case of all bridgesover 6.1m span. In case of arch bridges or other decked bridges


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with parapets where the height of the bank is considerable andany derailment can cause disaster, the aforesaid stipulations mustbe followed. Such bridges are to be personally identified by theDSE/Co-ordination of the division.

4.0 CONCLUSION

4.1 It is seen that for continuation of LWR in all zones, themaximum overall length of girder bridge is smaller for 60 kg railas compared to track with 52 kg/90R rail. It implies that thecontinuation of LWR on some bridges may not be possible ifrail renewal is done by 60 kg rail, although the LWR waspermitted on the same bridge with 52 kg rail.

4.2 It can be concluded that the track standards as laid down forgirder bridges are very sensitive to track structure onapproaches.

4.3 There is a need to carefully plan the Track Renewals on Girderbridges and review the existing track structure as per the laiddown track standards.

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