Improved Time-to-collision Considering Vehicle Speed Adaptation based on Trajectory Data

Abstract

For vehicle-vehicle conflicts, existing safety surrogate analyses are mainly based on the assumption of constant velocity. However, this assumption ignores the maneuver adaptations in the process of vehicle-vehicle interaction. In order to assess the risk during vehicle-vehicle interaction in a more accurate way, this paper proposes an improved TTC measure. The new TTC measure takes into account the impact of vehicle interactions by considering speed adaptations by the leading and following vehicle. The speed distribution was extracted from the Shanghai Naturalistic Driving Study data to calibrate the new TTC measure. A case study is then conducted to test the new safety measure. The result shows that the improved TTC presents different results from the traditional TTC measure illustrating the new measure potentially describe the crash risk in car-following conditions in a more detailed and precise way. The study will provide new ideas and methods in a more accurate and robust way for traffic conflict analysis.