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Abstract

This paper examines the effectiveness of applying chip seal friction courses in reducing accidents on low volume, rural roads. Chip sealing data from District 3 of the Utah Department of Transportation were used to examine accident rates before and after applying chip seal. Although accident rates generally decrease with an increase in skid numbers, existing linear and nonlinear relationships were found inappropriate to describe this trend. Nonlinear relationship between accident rate and skid number, estimated reductions in accident rates of more than 60 percent. However, before-and-after treatment accident rate comparisons using the data support these estimates only at statistically significant levels below 85 percent. The data indicate there is no definite relationship between accident rates and skid numbers on roads that were chip sealed.