Further studies of the skid resistance of asphalt surfaces in their early life

For some years it has been known that new asphalt surfacings have different skid resistance properties to surfaces that have been in service for some time. This is believed to be due to the presence of a film of bitumen binder on the new surface that is eventually removed by weathering and traffic. New types of surfacing introduced since the mid 1990s led to concerns that the risk of early-life skid resistance problems, and the time that any effects last, may have increased.

This report provides the results of a study to investigate the physical phenomena associated with the early life condition of new asphalt.

Summary of results and conclusions
The research identified physical phenomena that might lead to an increase in accident risk in some circumstances, and a subsequent accident analysis found that there was some evidence of a small increase in slight injury accidents in the first few months after laying a new surface on some types of road, but that these occurred in low-risk areas and were accompanied by a significant reduction in fatal accidents.

This report provides the results of a study to investigate further the physical phenomena associated with the early life condition of new asphalt. Friction measurements were undertaken on a number of trial sites and in-service roads to investigate the development of skid resistance with time and traffic, to compare the early life effects on different types of asphalt surfacings, to study the effect of temperature on skid resistance and the effects of gritting new asphalt surfaces.