The effect of skid resistance and texture on Crash Risk

This paper presents the results of a frst attempt to combine detailed information on road geometry (horizontal curvature, gradient and cross-fall), road surface condition (roughness, Tut depth, texture depth and skid resistance), cariageway characteristics (tegion, urbanirural environment, and trafic fw) and crashes. Such a study was only made possible because of annual surveys ofthe entre 22,000 lane-km of New Zealand's State Highway network made with SCRIM" since 1997, which involves simultaneous measurement of road condition and road geometry. Four subsets of road crashes were investigated: all reported injury and fatal crashes; selected injury and fatal crashes covering loss of control events; reported injury and fatal crashes occurring in wet conditions; and selected injury and fatal crashes occuring in ‘wet conditions. One and two-way tables and Poisson regression modelling were employed to identify critical variables and the form of their relationship with crash risk. Particular emphasis was placed on quantifying the effect of skid resistance and texture depth on crash risk.