Pedestrian accidents and left-turning traffic at signalized intersections

Abstract

The over-representation of left turning vehicles in accidents that occur at signalized intersections is an important problem in road safety. One aspect of this problem is that involving accidents between such vehicles and pedestrians. In this study, we explore and develop models relating the expected number of such accidents to the flow of left turning vehicles and the flow of pedestrians. We examine how two typical schemes for accommodating left turning vehicles influence the number of such accidents. These are a semi-protected scheme, where left turning vehicles face no opposing traffic but conflict with pedestrians and a permissive scheme, in which left turning vehicles have to find suitable gaps in the opposing traffic. Our results indicate that semiprotected left turns tend to be safer for pedestrians at low vehicular flows. The opposite is true for high flows of left turning vehicles. The models developed in this work also enable us to estimate what one should, on the average, expect the number of accidents involving pedestrians and left turning vehicles to be, and examine how the safety of a certain intersection compares to the norm.