Quantitative method of traffic conflict severity at intersection

In order to improve the precision in traffic conflict severity discrimination, a quantitative method for conflict severity at intersection was proposed based on the circle assumption of motor units and video detection technology. The moving parameters of motor units were obtained by using the video processing program and the real-time collected video images. Conflict detection and conflict time were determined by using iterative method. Considering the braking performance of vehicle, the critical value of conflict severity was obtained by the ratio of braking distance to instantaneous speed. The quantization value of conflict severity was established taking conflict time and critical value as parameters, and the severity of traffic conflict was quantified and classified. A certain intersection in Beijing was analyzed. Analysis result shows that the quantization values of conflict severity between two motor units increase from 1.32 to 2.45, and then decrease until no conflict exists. Driver would take emergency braking measures with the increasing of conflict severity, and then the conflict severity decreases until disappears. The quantitative result accords with the practical situation, and the method could be used in conflict detection and the severity quantification of traffic conflict conveniently.