Traffic Safety Evaluation of Highway Intersection with the Use of Conflict Severity Concept

Traffic conflict technique can be applied to quantitatively evaluate highway intersection traffic safety. The present study proposed that conflicts of different severity classes can be used in traffic safety evaluation when accident data are hard to acquire and the sample size of serious conflicts is not large enough. TTC (time to collision) was selected as index to judge the severity of conflicts. One second was determined to be the cut off value between serious conflicts and common conflicts, according to 85% cumulative frequency of TTC. Data of traffic volume and different severity conflicts in three periods of eight highway intersections were obtained to calculate six safety evaluation indices. Method based on gray clustering theory was used to process the six indices and to obtain safety sequence of eight highway intersections. Comparing with traditional method, the present method was verified more applicable.