Macroscopic and Microscopic Analysis of Effects of Scales of At-Grade Intersections on Road Traffic Safety

Abstract

Risk models by some traffic accident types with independent variables of geometric structures at 17 adjacent signalized intersections were identified using robust regression on Japan’s national Route 2 in Fukuyama City, Hiroshima Prefecture. A reduced size intersection using traffic inlands was excluded as an outlier due to its exceptionally low risk of rear end collision. Running trajectories of vehicles were estimated at every 1/30 second interval based on video observation data for the above outlier intersection and another intersection that is projected to be reduced in size. In addition, the running behavior of vehicles at the two intersections was analytically compared with accident risks. As a result, indexes of safety were found to be stable, despite relatively higher approaching speeds, at the reduced size intersection than at the standard size intersection. Left turn vehicles were found to maintain the lowest speeds when passing through a zebra crossing at the exit of the reduced size intersection.