Traffic flow characteristics and traffic conflict analysis in the downstream area of expressway toll station based on vehicle trajectory data

The limited road space and overlapping driving decisions may cause frequent speed and lane changes in the downstream area of expressway toll stations, which easily cause high accident risks. In this paper, micro vehicle trajectory data in the Huai'an South Toll Station was automatically extracted from aerial videos using the novel YSKT algorithm framework to analyze traffic flow characteristics. To further evaluate vehicle collision risks, the Extended Time-To-Collision (ETTC) and Post Encroachment Time (PET) indicators were employed. The results demonstrated that the longitudinal and lateral velocity and acceleration, the distribution of lane-changing points, lane-changing times, and travel time varied with road sections and vehicle types. Notably, the ETC vehicles had a higher risk of traffic accidents compared to MTC vehicles since their greater initial speed. The findings could provide valuable references for traffic managers to comprehensively understand traffic characteristics and evaluate traffic safety of similar complex road nodes.