Gap Acceptance Models for Left-turning Vehicles Facing Pedestrians at Signalized Crosswalks

Pedestrian-vehicle conflicts are considered as one of the most common safety problems at signalized intersections. The threat to pedestrian safety is mainly related to the interaction with turning vehicles, especially left-turners (left-hand traffic). This paper aims at analyzing the lag/gap acceptance behavior of left-turning vehicles considering pedestrian movement at signalized crosswalks. Furthermore, this paper addresses the severity of pedestrian-vehicle conflicts by analyzing vehicle speeds at the conflict points. User behavior at several signalized intersections with different geometric characteristics and traffic conditions in Japan are observed by using video cameras. It is assumed that pedestrian movements have their origin at either the near-side or far-side of the crosswalk. Accepted/rejected lags and gaps are extracted and classified depending on the direction of pedestrian movement. Cumulative Weibull distribution function is utilized to fit the observed lag/gap acceptance probabilities. It is concluded that drivers tend to accept shorter lags/gaps between pedestrians coming from the near-side of the crosswalk. Furthermore, it is concluded that drivers tend to accept short lags while being conservative about short gaps between several pedestrians. Simultaneously vehicles clear the conflict area with significantly higher speeds when accepting a lag with a single pedestrian. This indicates that such conflicts are more severe than those when facing several pedestrians.