Spatial and temporal distribution characteristics of traffic accident for highway vehicle queue tail

Based on the traffic flow data of recurrent congestion section on highway, the cumulative occupancy method was used to draw the fluctuating curve of traffic flow occupancy, which was used to judge the trajectory of vehicle queue tail at congestion section.The relations among occupancy, mileage position and time interval were analyzed.The inflection point of cumulative occupancy curve was determined.For the queue propagating and dissipating processes, the relations between traffic accident frequencies and temporal and sptial distances were analyzed, and the distribution features were statistically studied.Analysis result shows that when vehicle temporally and spatially approaches the queue tail, the occurrence frequency of traffic accident obviously increases, and the temporal distance and spatial distance follow the normal distribution centered on the queue tail.Normal distribution curves in different driving directions have no significant differences, but have significant differences between congestion propagation and dissipation processes.The developed joint normal distribution model of traffic accident occurring probability can be used to predict the traffic accident risks in the vicinity of queue tail, and to provide the theoretical foundation for applying dynamic traffic control for improving highway safety.