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 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. Averaging methods were used to develop trends and minimize scatter. A moving average for progressively ordered sets of five test sections yielded more definite results. The expression of accident occurrence that correlated best with skid and slip resistance was wet- weather accidents per 100 million vehicle miles (161 million vehicle km). Accidents (at 70 mph (31 m/s)) increased greatly as skid numbers decreased from 27. Analysis of peak slip numbers and accident occurrences indicated similar trends.