Low adhesion between rail and wheel can be caused by moisture on the rail mixing with the film produced by 'leaves on the line' or other contaminants, such as rust or grease. It can be particularly severe in autumn, but low adhesion can occur at any time of year, resulting in disruptions to passenger journeys. It can also cause safety risks, such as signals passed at danger and station overruns.
Low adhesion is also a barrier to increasing capacity. Being able to stop trains reliably and predictably under a variety of adhesion conditions is essential to the safe running of a busy and reliable railway.
In response to this adhesion challenge, we have worked alongside industry to develop a wide-ranging ADHEsion REsearch (ADHERE) programme.
Recent implementation has included piloting double variable rate sanders and moisture sensors on the Birmingham Cross-City Line. Wider industry trials planned for autumn 2020 include high-speed cryogenic railhead cleaning and microwave generated plasma track treatment.