Accidents on Rural Interstate and Parkway Roads and Their Relation to Pavement Friction

Friction measurements were made with a skid trailer at 70 mph (31 m/s) on 770 miles (1240 km) of rural, four-lane, controlled-access routes on the interstate and parkway systems in Kentucky. Each construction project was treated as a test section. Accident experience, friction measurements, and traffic volumes were obtained for each. Various relationships between wet-weather accidents and skid resistance were analyzed. The expression of accident occurrence which correlated best with skid and slip resistance was wet-weather accidents per 100 million vehicle miles. Accidents increased greatly as Skid Numbers (70 mph or 31 m/s) decreased from 27 ± 1. Analysis of Peak Slip Numbers and accident occurrences indicated similar trends