Research project explores the benefits of different sand types to improve adhesion
Managing low adhesion is a priority area for rail. Every year, this issue costs the industry and the wider society millions of pounds.
The risk of low adhesion is actively managed, in part, by the application of sand at the wheel-rail contact during braking applications.
Two grades of sand are currently approved in Railway Group Standards for use in sanding equipment. These are:
- Low-particle-size sand is used for traction enhancement.
- Larger-particle-size sand is specified for braking enhancement.
Recent academic evidence has suggested that lower-particle-size ‘traction’ sand could be an effective alternative to coarser ‘braking’ sand.
Through the Strategic Partnership between RSSB and the University of Huddersfield, full-scale testing on the HAROLD rig was undertaken. The aim was to assess the potential benefits of lower-particle-size sand in braking applications.
A comprehensive plan was created to test the braking performance in low-adhesion conditions for both sand types in a range of representative loading scenarios.
Low-adhesion leaf layers were consistently formed at the wheel-rail interface for each test. Sand was applied at the interface under braking application, and the ability for each sand type to raise
The results found that there was a consistent effect of improved adhesion across both sand types in braking applications.
However, no significant differences were observed between the two sand types. The results at this stage would indicate that there would not be an advantage of using traction sand in braking applications.
Future work could look at a wider variety of sand types. It could also look at the performance of different sand types in traction.