Variation in the level of skidding resistance of road surfacings over the months of a year is used to quantify the benefits of skidding accident reduction when skidding resistance is increased. Month-to-month changes in skidding resistance are related to the corresponding changes in skidding accident frequency. The possible effect of changes in other factors such as traffic density and light conditions are also considered. Categories studied include road usage, traffic speed, class of road, class of vehicle and region within Great Britain. Main findings were:- 1. Correlation was found between seasonal changes in wet-road skidding resistance and wet-road skidding frequency for all categories. 2. Month-to-month changes in traffic volume and light conditions have relatively little effect on skidding frequency. 3. The estimated reduction in skidding frequency per unit change in skidding resistance was similar for most categories. 4. Good correlation was found between wet-road skidding resistance and dry-road skidding accident frequency for most of the categories. 5. Although the benefit per unit increase in skidding resistance is less under dry road conditions, the overall importance is as great because of the larger number of accidents reported on dry roads. (A)

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