WheelChex

Quantifying the Effect of Out-of-round Wheels on Switches and Crossings

Partners: Alstom Train Services, Carillion Rail, CCS, Railtrack
Researchers: C Roberts, A Pearce, RW Lewis
Dates: 2001-2002

It is well established that out-of-round wheels cause significant damage to the railway infrastructure. On the whole, research to date in this area has concentrated on the modelling of track deterioration characteristics over time. However, little research has been focussed on quantifying the effects of out-of-round wheels at switch and crossing (S&C) installations.

The purpose of this research is to look at the data generated by two separate computer systems. One system looks at train wheel profiles whilst the other system looks at the condition of points at a major junction. Through intelligent computing techniques we hope to show how vehicles with high impact forces (out-of-round wheels) have a detrimental effect on the S&C.

The condition monitoring system installed at Hanslope Junction was developed by the University of Birmingham. It monitors spare relay contacts on signalling relays along with analogue sensors in the form of load pins and current transducers on the point machines. From the information received from these sensors the system, through a set of digital rules and algorithms attempts to quantify the “health” of the points at Hanslope Junction and predict possible failures before they happen.

WheelChex™ has been developed by AEA Technology Rail and is installed at Cheddingon. The WheelChex™ system collects data about the trains passing over the site by the use of strain gauges attached to the web of the rail between sleeper supports. The system can provide such details as the train speed, weight, axle loadings and peak wheel loads (impact forces).

The sites two systems are 32km apart on the West Coast Main Line. By using the TRUST database system it was proved possible to assign train headcodes to the data generated by the Hanslope and Cheddington systems based on time and date information. This headcode data forms the basis of data correlation between the two systems.

It can be established that a significant proportion of S&C failures are caused by vibrations resulting from poor train wheel-sets. At present the correlation between poorly maintained trains and S&C failure is neither provable nor quantifiable. This works aims to search for patterns between data gathered from a wheel force impact measurement system and a point machine health monitoring system. It is hoped that it will be possible to quantify the effects of poor wheel-sets as well as developing software algorithms for detection of incipient failures at S&C caused by poorly maintained rolling stock.

http://www.railway.bham.ac.uk/wheels.htm

WheelChex is a brand name for a Wheel Impact Load Detector (WILD) system used by Network Rail.

This line-side equipment measures the impact upon the railhead of each wheel of a passing train, and provides details of all trains with wheel loads outside acceptable limits.

When an alarm message is generated by WheelChex, Network Rail Operations Control will identify the train involved and notify the signaller at the centre through which the train will shortly pass.

This will enable the train to be stopped at a suitable location for the driver to examine the wheel-sets concerned.

The train can then be taken out of service, or speed restricted to minimse the possibility of derailments or damage to track caused by wheel defects or overloaded vehicles.

The WheelChex at Braidwood made the news on 29th September 2004 when an alarm was generated by 390041 working the first relaunched “Royal Scot” Glasgow – London Euston at the launch of Virgin West Coast‘s accelerated timetable. The train was terminated early at Carlisle.

WheelChex locations in Scotland

Name Mileage Direction Route
Braidwood WCM1: 80m 1276y Up & Down West Coast Main Line, south of Carluke
Innerwick ECM8: 33m 1374y Up & Down East Coast Main Line, south of Dunbar
Howwood AYR3: 12m 1700y Up & Down Paisley – Ayr line
New Cumnock GSW: 56m 1540y Up & Down Kilmarnock – Dumfries – Carlisle line
Philpstoun EGM1: 32m 22y Up & Down Edinburgh & Glasgow, east of Linlithgow

Leave a comment