Track maitenance Practices

 on Heavy Haul routes of Foreghin Railways

and  

Suggestions for IR

Axle Loads on various RailwaysFollowing are the axle-loads operated on some big railways

• China: 20.5 t

• America: 30 t

• Australia: 40 t

• India: 22.9 t

Why Heavy Haul carrying?

The growing needs of the industry and commerce in the countries through out the world has necessiated carrying of higher loads of Iron Ore, Coal etc through Railway Networks. Increasing of load carrying has become inevitable.

Why Heavy Haul ? continued…..

To increase the load carrying following options are available

• (i) Introduce more number of trains• (ii) Increase the number of wagons per train• (iii) Increase the load per wagon (i.e. Heavy Axle

Loads).Out of these three options the first two options have limitations due to system contrains and econmic point of view. The third option is widely followed by the Railways world over due the conomic benefits and adoptability.

Problems faced in heavy haul track maintenance

• In the P-way side the track and particularly the Rail being immediately supporting the rolling stock is the main component affected.

• Besides the Rails deterioration of track geometry is another concern. These two things are discussed in this presentation.

Problems with Rails• Rolling contact Fatigue (RCF): Defects form in response

to millions of intense wheel rail contact cycles that repeatedly over-stress the surface or the sub-surface material.

• Wear: It is the gradual attrition of metal through stress and slip, whereby small particles are removed from rail surface.

• High lateral wear: in the outer rail on sharp curves• Shelling: The surface layer of rails, under RCF strain

hardens and fractures, initiating surface crack. These cracks can grow under subsequent loads, link up and lead to shelling.

• Rail plastic flow:

Problems with Rails continued….• Head checks: RCF cracks that penetrate into the rail head caused

by high rail wheel contact stresses.• Spalling: caused when multiple head checks meet and popup at

the rail surface.• Corrugations: RCF defect imitated and propagated by a

combination of non-uniform RCF crack growth, plastic flow in combination with wheels/track dynamic phenomena.

• Flat Rail: Extreme areas of plastic flow on rail head.• Dipped welds: Associated with changing steel metallurgy at heat

affected zone and extended by inaccurate setup of rail welding machine.

• Wheel burns: Ares where locomotive wheels loose traction and spin on rail.

Problems with Rails continued….Problems with welds:

1. Allumino thermic welds:• Fatigue failures at the edge of collar: Stress

concentration initiates at the edge of collar either below the base or at the web/base fillet.

• Center line shrinkage defects in the rail foot: Initiates a vertical fracture at the center line of weld.

• Straight break failure at the edge of weld collar

• As per a study conducted in Australia in heavy haul routes the percentage of AT weld failures in Rail breaks is 76%.

Maintenance practices in Foreign railwaysA systematic track maintenance involves the following stages

• Monitoring: Track geometry, Rail profile etc

• Analysis: Failure, Condition defects, Quality indices etc

• Optimization: Degradation speed, Work frequency etc

• Planning: Maintenance and repair works

• Scheduling: Creating work orders

• Execution

Track monitoring practices in foreign railways

Track geometry1. Roger CVRD measuring system: Used in Brazil etc,

measures the following parameters

• Track geometry and rail profile

• Rail surface defects

• Track video inspection

Salient features: No moving parts, multi point high speed communication links, lasers and special sensors, samples at every 25 cm of rail length, entire speed range of 0 to 120 kmph

Track monitoring practices continued….

Weld geometry1. RAILPROF: Is a tool for accurately measuring

longitudinal rail geometry. Low weight (6 kg for RAILPROF 1000) and robustness could be realized through the use of high tech materials developed in space technology.

High accurate measuring equipment with accuracy +/- 0.03 mm

Works with a digital straight edge based on principles of eddy current.

Low weight: about 6 kg.

Short length: 116 cm.

Track monitoring practices continued….

Wheel Impact Load Detector (WILD) The WILD is a strategic device for the protection of rail infrastructure. High impacting wheels can dissipate on the order of twenty-five horsepower each, degrading track, ballast and bridge structures while reducing bearing and other vehicle component lives.

Rail Surface Fatigue Measurement from a Moving Vehicle:

A new technique to detect and quantify rail surface fatigue cracks from a fast moving railway vehicle has been developed. Output from the system can be used to help program track maintenance activities, especially rail grinding.

Track monitoring practices continued….

One Billion Gross Tons Heavy Axle Load Testing at FASTFacility for Accelerated Service Testing (FAST) is available at US Federal Railroad Administration (FRA). Over 1,000 million gross tonnes or MGT (1,100 million gross short tons) have been accumulated in the testing.

Analysis has shown that bridges, poor quality rail, poor ballast/subgrade conditions, field welds, and special track -work can acts as constraints to increased axle loads.

Conversely, premium track components, improved maintenance, and improved suspension trucks tend to mitigate the effects of HAL traffic on track maintenance costs.

Track monitoring practices continued….Laser-based ultrasonic rail inspection system:The AAR expanded efforts in 2004 to develop a laser-based ultrasonic rail inspection system.This nondestructive testing (NDT) apples mechanical energy to the rail at any location accessible by a laser beam.The laser-based system can successfully detect flaws located in the head and base of the rail.When a flaw is present, radio frequency signals (RF) from ultrasonic wave modes being monitored (longitudinal, shear and surface waves) are either attenuated, eliminated or shifted relative to time or distance as represented on a cathode-ray tube (CRT).When a flaw is not present, strong and distinct RF signals from the various ultrasonic wave modes monitored become apparent on the CRT.

Latest practices of track maintenance

Rail grindingRail grinding is a fixed part of rail maintenance on most heavy-haul railroads, but grinding programs are not static. Preventive grinding: In the preventive-gradual approach, the rail is transitioned to the desired profile and a crack-free state through a series of frequent, single-pass grinding cycles.

Corrective grinding: adopted for eliminating surface defects such as corrugations, metal flowing etc on rail top.

Rail grinding

Latest practices of track maintenance continued…

TOR friction controlTop of Rail Friction Control is the method in which the frictional forces between the rail table and wheel are reduced by applying friction modifiers which controls friction-coefficient to an optimum value.Whereas the conventional gauge face lubrication is applied on the gauge face of the high rail using lubricants.

Advantages:1) Reduce lateral curving forces on curves.2) Reduce rail-wheel wear

Methods:1) Way side applicators2) Locomotive based applicators3) Mobile--car-based applicators

Latest practices of track maintenance continued

StoneblowerThe Stoneblower is a new machine developed as an alternative to traditional tamping methods. The machine utilizes a process, which pneumatically injects ballast under the tie to achieve track positioning to an accuracy of 1.0 mm without disturbing the pre-existing compacted foundation. The track is immediately available for unrestricted line speeds.

Stoneblower Special Features:

Complete vertical and lateral track design capabilities.       

Complete track recording system.                 

Designed and manufactured to rigorous reliability standards to ensure required machine availability and reliability levels.

StoneBlower

Suggestions for IRWorld over have increased axle loads and adopted innovative new technologies in the fields of track monitoring, analysis and maintenance.

Rolling Contact fatigue and Rail grinding: With the adoption of higher axle loads and higher UTS rails the problem of Rolling Contact Fatigue of rails is the main concern every where. Rail grinding is one of the established and widely followed maintenance practices in the foreign countries. Recommended for adoption in IR.

TOR: Top of rail friction control (TOR) is another subject gaining importance word over. The friction modifiers are applied on the top of rail. It is suggested that the same may be gradually followed in Indian railways.

Advanced track monitoring practices like electronic track geometry recording, rail profile measurement etc are suggested for adoption in Indian railways.

Formation rehabilitation machines: with improved technology have developed which can give progress up to 100 m per hour. It is suggested that IR can plan to procure one or two such machines for use in heavy haul routes having patches of formation problems.

Mobile flash-butt welding in maintenance at site: In the foreign countries mobile flash-butt welding plants are being deployed for renewal welding in maintenance works to remove bad welds. It is strongly recommended that in india we should start deploying the mobile flash-butt welding plants for removal of old thermit welds on large patches of track length with proper planning for minimum corridor blocks.

Thank You