Maximise track circuit performance for a safer and more reliable service
Track circuits can detect trains and control signalling systems. Wheel/rail contamination can electrically insulate a train’s wheels from the rail. This can fail to ‘short’ a track circuit so that it appears that no train is present. These incidents are referred to as WSTCFs. They can compromise the integrity of the system. In a worst-case scenario, they can result in collisions.
GB rail stakeholders noted inconsistencies in the management and reporting of WSTCFs on several GB mainline routes. They requested research to better understand how railhead and wheel contamination affects track circuit performance. They also wanted improved insight into available mitigations.
This project analysed WSTCFs occurring on the GB mainline over a 15-year period. It reviewed WSTCFs occurring on six case study lines. It did laboratory and track testing and produced good practice guides.
A list of parameters was developed to assess the risk of WSTCFs on the case study lines. These parameters can be used to identify potential WSTCF risk areas. They can also be used to assess lines on which future problems may occur.
Laboratory testing identified the approximate train axle loads needed to overcome different contaminant layers.
The inductance of the track circuit’s relay coil was found to be a key cause of large spikes in voltage. It was a significant determinant of overall track circuit behaviour.
This project gives industry better scientific and historical insight into how railhead and wheel contamination affect track circuit performance. It also proposes a variety of mitigations to reduce the frequency and impact of WSTCFs.
The project’s outputs will inform changes to several industry standards. This includes Rail Industry Standard RIS-3708-TOM Arrangements Concerning the Non-Operation of Track Circuits During the Leaf Fall Contamination Period.
Successful implementation is expected to reduce the frequency of WSTCFs. The estimated saving as £965k over a 15-year period. These savings are from reduced safety risk, delays, and investigation costs.