Investigating secondary pedestrian-vehicle interactions at non-signalized intersections using vision-based trajectory data

Abstract

Vision-based trajectory data provides great details for investigating microscopic behavior and road safety at the level of interactions. Most studies investigating pedestrian-vehicle interactions at non-signalized intersections have focused on interactions at the crosswalk on the same approach where the vehicle is coming from, which are referred to as primary interactions in this study. However, secondary interactions, defined as interactions between vehicles exiting the intersection and crossing pedestrians, have not been adequately studied. Second interactions can pose more dangers to pedestrians due to the driver’s unclear knowledge of right-of-way, acceleration attempts to recover the speed, and the complex situation the driver faces in the intersection. This paper aims at studying the safety issue of secondary pedestrian-vehicle interactions at non-signalized intersections. For that purpose, a methodology is proposed based on surrogate measures of safety and behavioral measures derived from vision-based trajectories. This methodology is implemented through a case study involving ten all-way stop intersections from Montreal, Canada. Road user trajectory data are automatically extracted from the videos. Different measures are used in the study: from the interaction analysis that determines vehicle-pedestrian interactions based on a Distance-Velocity (DV) model, average crossing speeds and vehicle approaching behaviors in terms of speed and acceleration. Computer tools are developed to extract these measures from the trajectory data. Based on these measures, a comparative analysis is carried out between primary and secondary interactions. Results show that secondary interactions are more dangerous than primary interactions. Among the three secondary interaction types, secondary through interactions are the most dangerous.