modernization of track.docx

7/27/2019 Modernization of track.docx

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Sub: Modernization of track.

1.0 Track Structure Inputs

In order to have track compatible with higher axle load and higher speed

operations, the modernization of Track is essential. The Track structure

shall be such that operation of 25t freight at 100 Kmph and Passengertrains with speed at 200 Kmph is feasible without any significant

restriction with reduced maintenance requirement. The broad parameters

to be kept in view while deciding the modernization inputs are

.1 Uniformity of Track structure: Multiplicity of track components result

in high inventory. So standard track structure shall be adopted..2 It should be feasible to continue the long welded rails on all locations

without any restriction.

.3 The maintenance regime shall be predictive rather than periodicitybased.

.4 Suitable diagnostic aids shall be available so that dependence onmanual inspection is minimized and safety is enhanced.

With above in review, the details are deliberated in following Para.

1.1 Rails:

60 kg 90 UTS Rails are used on IR at present. The existing Rails suffer

drawbacks of being brittle in nature and inadequate corrosion resistant

properties. As assessed in Lab. evaluations, Ductility and corrosionresistant properties can be improved even for 90UTS rails by suitable

micro alloying. BSP is already working on new chemistry of rails.

With commissioning of DFC, the operation of 25t axle load will be

regular on majority of routes. The Rails stresses for 60 Kg 90 UTS rails

are exceeding safety limits. Thus Higher Rail section of 68 Kg will havebe used.

Field weld are inherently weak, thus need of rolling longer Rails. Onlylong Rails of length 130m need to be supplied to reduce number ofwelds.

Suitable arrangement for transportation and unloading of Rakes will have

to be developed. The new EUR rakes shall be capable of running at 100Kmph with 260/ 520 m panels.

Thus, for new constructions and renewal works, 68 kg 90UTS railswithin improved ductility and corrosion properties shall be used.

1.2 PSC Sleepers: Size of PSC


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The existing design of PSC sleepers has served the present traffic needs

satisfactorily. However, the design needs review particularly onfollowing accounts:

1. The increased longitudinal and lateral resistance of track will bepre requisite for continuation of long welded rails. Heavier

sleeper will significantly add to resistance of track. IR sleepersare much smaller in size as compared to one used in Railway

systems worldwide.2. The rail seat area is small, resulting in small plan area thus size of

GRSP. This has been one of the major factors for poor in service

performance of rubber pads. There is need to increase Rail seat

area.

The new design of PSC sleeper shall be such that it has more concrete

mass with reduced reinforcement and increased plan area at Rail seat.

The rail seat shall be designed such a way that it is suitable for 68Kg

UIC rails with feasibility of using 60Kg rails, so that the rail replacementsubsequently does not require sleeper replacement. The rail seat able to

accommodate the width of rubber pad minimum 200mm wide. It shall bepossible for existing Tamping machines to work without any limitation.

sleeper to be

tentativelydecided.

1.3 Fastening System:

With the existing fastening system, toe load in range of 600 - 800Kg is

observed in service. In ideal condition, rail - sleeper resistance andsleeper - ballast resistance should be almost of the same order to avoid

the rail creep. With new design of sleepers, the fastening system will also

require change. While designing the fastening system, following broad

guide lines be adhered:1. In service Toe load - 1100 to 1200Kg2. Minimum Thickness of GRSP: 10 mm3. Reduced tolerances in fastening components

The performance of fastening system depends upon the combined effect

of tolerance in ERC, Liners and SGCI inserts. In case the tolerances ofindividual component are added on one side, even with new fastening

component the toe load can be in range of 400 to 500Kg, which is

grossly inadequate. Thus, the regime of fastening procurement system

also needs review. The system of tolerance individual components shallgive way to overall tolerances in complete fastening system. The

complete fastening system should be procured as one unit with strict

performance criteria rather than individual components.

Details to be

provided.

1.4 Rail Welding:The supply of long rails (rolled rail length of 130m) will substantiallyreduce the quantum of welding.


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For new construction/ planned renewals, only flash butt welds shall be

allowed. No dispensation shall be given for undertaking AT welding inany situation. The site welding shall be done necessarily with Mobile

flash welding plant.

The casual welding/repair weld shall also be done by the mobile Flashbutt welding Plants. As already decided, the procurement of Mobile

Flash Butt welding plants shall be expedited.

For urgent repair welds, only improved SKV welding technique with

compressed air pre-heating, three piece mould, auto thimble and single

shot crucible shall be used. The strength parameters for SKV weldsshould also be reviewed and it should be comparable with Flash butt

welds.

1.5 Ballast:The clean ballast cushion of 350mm shall be mandatory for all newconstructions/ Planned renewals with width of shoulder ballast as

specified at present.

Details to beprovided.

1.6 Formation:For better retentively of ballast, formation width shall be suitably

increased to provide minimum cess width of 600mm to facilitate unobstructed movement of small track machines and labour.

Stable formation is pre requisite for heavy axle load operation as well asfor high speed. For new constructions, minimum 75mm blanket shall be

provided and formation shall be well compacted.

Details to be

provided.

1.7 Switch Expansion Joint:The switch expansion joint should not have any discontinuity on runninggauge face for reliable service life. The improved SEJ designed by

RDSO, shall be standard SEJ and conventional SEJ should be phased

out.

1.8 Glued Insulated Joint:Glued insulated joints are discontinuity in track and are not desirable. In

new construction (new lines as well as Gauge conversion), the signaling

system adopted should be such that there is no need for glued insulatedjoint. On existing routes, with improvement/ modernization of signalingsystem, the glued insulated joint should be gradually phased out.

Prefabricated Glued Joints require minimum Two additional welds at

each location. As such, till such time the glued insulated joint isrequired, technique for in-situ manufacture of glued joint shall be

developed and standardized. This will reduce the number of site welds


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which are weak link in track. The manufacturing methodology of glued

insulated joint shall be reviewed thoroughly to obtain consistency of insitu Glued Joints for better in service reliability. Only in-situ glued joint

shall be allowed.

1.9 Bridge Sleeper:On Girder Bridges, Steel channel sleepers are mostly used at present.The in service performance of these sleepers have not been satisfactory

due to number of loose components and corrosion problem. The

composite sleepers have performed well in trials and are properreplacement of bridge timbers due to inherent advantage of ease in use.

The composite sleeper shall be standardized for use on steel girder

bridges and shall be the bridge sleeper for track.

The suitable fastening system having zero toe load and adequate

torsional resistance will be needed for continuation of long welded rails

over Girder Bridges. Such fastening systems shall be designed anddeveloped, which will be standard fastening for use with compositesleepers.

Details to beprovided.

1.10 Turnouts:-

The fabricated curved switches and CMS crossings being used at presenthave limitation on maintainability and continuation of LWR. These

limitations are addressed in Thick web switches and weldable CMS

crossings. As such, it shall be mandatory to use Thick web switches andweldable CMS crossings on all new constructions and Planned

renewals. This will facilitate immediate continuation of long weldedrails through turnouts.

The spring setting device shall be integral part of thick web switches.

The design shall be reviewed and proper design of SSD shall be

provided.

The fastening system for turnouts shall be re-designed to address the

problem of working out of rubber pads in crossing area and other suchlocations.

On high traffic density routes explosive depth hardening crossing shallbe provided.

There is also need to develop the suitable design of swing nose crossing

for use on high speed routes.

Details to be

provided.

1.11 Level Crossing:In new constructions, no level crossing or surface crossing shall be


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provided in any circumstance.

On existing network, all out efforts shall be made for elimination of

level crossings. Till such time, the LCs are eliminated, the arrangement

at Level crossing needs review to provide arrangement which does not

require provision of check Rails. The surfacing of existing levelcrossing shall be re-designed and standardized so that there is no

requirement of check rails & resurfacing shall be possible without delay.This will also eliminate the restriction of continuation of LWR at

number of locations.

1.12 Approach slab at Bridges:

Continuity of track modulus over sufficiently longer length is essentialfor higher speeds. Slab bridge approaches suffer drawback on this

account. The provision of suitable approach bridge slab shall be

mandatory for all new constructions.

2.0 Diagnostic tools for Track inspection and maintenance:With increasing traffic, manual inspection is no longer effective for

planning the maintenance activity. The traffic blocks for maintenanceare also decreasing considerably. As such, the maintenance regime has

to shift to predictive maintenance, for which Continuation monitoring of

track is necessary.

2.1 Computerized Track maintenance management & monitoring

system:

The track management system developed so far takes the inputs onlyfrom TRC & OMS. There is need to develop a system on line with OHE

monitoring system, which continuously monitors the system and sendalert. As such, the TMS need to be upgraded to incorporate the user

friendly features with inputs from other diagnostic tools which are to be

provided during modernization.

2.2 Ultrasonic Testing of rails:The present system of USFD testing of complete network with

pedestrian SRT/ DRT will not be a reliable system with increased traffic.

Thus, Vehicle based ultrasonic testing with follow up testing by

pedestrian USFD machines shall be implemented. Both the systems i.e.vehicular and Pedestrian should be GPS compatible for precise location

on defects and monitoring flaw growth rate.

The vehicle based USFD system shall be capable of preciously recording

the defect at speed of about 40 to 50 Kmph with facility of automatically

preserving both the A and B scan of defects.


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The pedestrian testing should have facility for hand probing and shall be

able to record the details of defects with flaw size.

The software system of USFD should be capable of comparing the

recording of different runs and shall be compatible for direct input with

track management system.

2.3 Rail stress monitoring system:The long welded rails require lesser maintenance but require continuous

monitoring for Rail stresses to prevent Track Buckling and Railfractures.

The continuation of long welded rails through various locations will

require regular monitoring of locked up thermal rail stresses and

determination of stress free temperature for deciding the need based de-stressing of welded panels.

The following two systems need to be implemented:a) Stationary rail stress continuous monitoring system: This shall beinstalled at critical/vulnerable location such as bridges, bridge

approaches, sharp curves, gradients etc. for safety against rail

breaks and buckling tendency. The software shall be compatiblewith direct inputs to track management system.

b) Portable rail stress monitoring system and determination of stressfree temperature: Determination of stress free temperature isessential for planning need based distressing of LWR. The

portable system shall be deployed for periodically monitoring of

stress free temperature with provision of necessary software for

calculating the factor of safety against buckling of track. Onesystem for each sub-division will be essential. System shall be

compatible for direct interface with track management system.

2.4 Broken rail detection system:The rail weld fractures are major safety hazard. The system of brokenrail detection system and warning system with suitable interface to

signaling system shall be deployed to warn the broken rails to prevent

mishap.

2.5 Installation of way side lubricators:

With introduction of heavier axle loads and rail grinding, even for mildcurves gauge face lubrication will be required. Manual lubrication is not

effective, as lubricant is lost after few trains. Automatic gauge face

lubricators shall be installed on all curves on Indian Railways as pertechnical specification of track based lubricators issued by RDSO.

Study shall also be undertaken to judge efficacy and need for top of raillubrication in heavily graded/curved section. Worldwide experience has


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been very encouraging. After detailed study the system top of rail

lubrication shall be developed and adopted.

2.6 Vehicle monitoring system :Non conformities in rolling stock such at wheel flats, out of round

wheels in adequate/in effective suspension system increase the dynamicaugment on track significantly. There is need to install way sidedetectors such as WILD which give the dynamic augment on track for

preventive action to control rail weld fractures. The WILD shall be

installed by Track department, as not much headway has been made inthis regard.

modernization of track.docx

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