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 closely with industry to develop a wide-ranging ADHEsion REsearch (ADHERE) programme, contributing towards ensuring a safe and efficient rail network. See all ADHERE projects in the research catalogue.
Onboard equipment and systems, such as sanders, are used by the industry to help manage and mitigate low adhesion conditions. Incremental improvements and new developments present opportunities to reduce delay minutes and associated costs that are incurred as a result of low adhesion.
Cleaning contamination from the railhead costs Network Rail around £40m each year. A better understanding of the benefits of current rail cleaning methods, and innovative new ways of cleaning and treating rails, could help keep services running.