Investigating factors that affect traffic conflicts between bicyclists and right turning vehicles at signalized intersections

Abstract

There is increasing interest in designing infrastructure systems to promote the safe use of forms of active transportation such as bicycling. Collision data, which are typically used in road safety studies, may be incomplete and the use of such data is reactive as it requires collisions to have already taken place. As such, alternative approaches for evaluating the safety effect of various infrastructure attributes, such as the use of surrogate safety measures, specifically traffic conflicts, are becoming popular. Most collisions between bicyclists and vehicles occur at intersections and, of these, collisions between right turning vehicles and bicyclists form the majority. The main objective of this study was to use cross-sectional regression models to investigate various intersection characteristics, including geometry, signal phasing, and bicycle infrastructure, to determine which attributes are significantly associated with right turning conflicts and how this may vary with different conflict severity levels. An increase in right hook vehicle-bicycle conflicts was found to be associated with the presence of a dedicated right turn lane on the left of a bicycle lane, having a downgrade on the approach to an intersection, the absence of pavement markings, a decrease in the value of lateral offset, and an increase in bicycle and right turning vehicle volume.