TRL report

1 primary work

High and Low Speed Skidding Resistance

by P G Roe, A.R. Parry, and H E Viner

Published 17 February 1999

A key aspect of road safety is the provision of adequate friction between the tyre and the road surfacing. Current UK standards for skidding resistance are based on studies carried out in the 1970s, but as traffic levels and speed have increased and new surfacing materials have developed there has been a clear need for further research. This report contains the result of research commissioned by the Highways Agency in 1995 to assess the influence of texture on the relationship between high- and low-speed skidding resistance for the wide range of surfacings now used on UK trunk roads. It discusses the work done in the study, the results of the first phase of analysis and briefly looks at the practical implications which emerge.Significant findings include: further evidence that friction decreases with speed, and that this is more marked for surfacings with low texture depth; texture has a greater impact on loss of friction at low speeds than previously thought; and the effect of texture is similar for both random-textured and transverse-textured impermeable surfacings. This study confirms the basis of current standards and points the way for the development of future specifications.