A step change in autumn braking
When variable-rate sanders apply more sand to the wheel-rail interface at higher speeds, braking in low-adhesion conditions can be significantly improved.
The findings on variable-rate sanders came from early lab-based feasibility studies, followed by a comprehensive programme of track testing on Class 387s during 2019.
An in-service pilot with West Midlands Railway confirmed the results. This paved the way for retrofitting variable-rate sanders to existing rolling stock and incorporating them into new designs.
South Western Railway and Porterbrook retrofitted to 39 units from their Class 158 and 159 fleets in time for autumn 2024. Although autumn conditions vary every year, there seemed to be an improvement. In 2022, there were three reported low-adhesion slide incidents and four in 2023. But in 2024, with the new sanders, there were none.
Northern, also working with Porterbrook, retrofitted variable rate sanders to its Class 323 fleet. The whole fleet (34 units) was retrofitted and in service for autumn 2024. There were no reported low-adhesion slides for the Class 323 fleet in 2024.
‘The retrofitment of single variable-rate sanders to SWR’s Class 158 and Class 159 fleets has so far been one of the most effective modifications to improve braking capabilities in low adhesion conditions. Early results show a reduction in low-adhesion slide incidents and improvements in operational performance in autumn.’
‘With double variable-rate sanders now in service on the Class 323s, we have seen improvements in braking capabilities and operational performance on routes that routinely experience low adhesion conditions.’
