A Probability-based approach for assessing the relationship between road crashes and road surface conditions

Skid resistance is a condition parameter characterising the contribution that a
road makes to the friction between a road surface and a vehicle tyre. Studies of
traffic crash histories around the world have consistently found that a
disproportionate number of crashes occur where the road surface has a low level
of surface friction and/or surface texture, particularly when the road surface is
wet. Various research results have been published over many years and have
tried to quantify the influence of skid resistance on accident occurrence and to
characterise a correlation between skid resistance and accident frequency. Most
of the research studies used simple statistical correlation methods in analysing
skid resistance and crash data.

Findings from research projects do affirm various levels of correlation between
skid resistance and accident occurrence. Studies indicate that the level of skid
resistance at critical places such as intersections, curves, roundabouts, ramps
and approaches to pedestrian crossings needs to be well maintained.

Management of risk is an integral aspect of the Queensland Department of Main
Roads (QDMR) strategy for managing its infrastructure assets. The objectives of
this paper are to explore current issues of skid resistance in relation to crashes,
to provide a framework for a probability-based approach to be adopted by QDMR
in assessing the relationship between crash accidents and road surface
conditions.