Research on Traffic Safety on Freeway Merging Sections Based on TTC and PET

Abstract

Since the traffic safety of freeway interchange merging sections and the accidents occurred in this areas can not meet the requirement of statistical analysis, this paper employed traffic conflict technique to analyze the safety situation of freeway merging sections. The traffic data of vehicles through the merging sections are collected and analyzed. These data include the vehicle type, speed, time headway and others based on the features of individual vehicle. Then two methodologies are developed, the first is based on time to collision (TTC), which can calculate the rear-end conflict number, while the second is based on post encroachment time (PET), which can calculate the lane-change conflict number. The results show that these surrogate measures can quantitatively describe the rear-end conflict situation and lane-change conflict situation.