The Influence of Driver Sight Distance on Crash Rates and Driver Speed at Modern Roundabouts in the United States

Abstract

This paper investigates the relationship between driver sight distance and vehicle speed and crash rates at roundabouts. Data were collected at 26 single-lane roundabouts and models were developed that predicted the 85th percentile approach speed, 85th percentile entrance speed, and the difference between the 85th percentile approach and 85th percentile entrance speeds. Models were also developed to predict vehicle crash rates at roundabouts considering driver sight distance. The results from the models confirm that vehicle speeds and crashes at modern roundabouts are related to driver sight distance. Providing more than the minimum required sight distance can lead to higher speeds that reduce safety at roundabouts.