Evaluating Traffic Conflicts and Crash Risk in Nighttime Maintenance Operation Areas of Highways Using Vehicles’ Trajectory Data

Highway pavement maintenance operations are increasingly conducted at night, when lane reduction combined with the complexity of nighttime conditions elevates driving risks within maintenance operation areas. Therefore, it is essential to clarify the impact patterns of traffic conflicts and driving risk in nighttime maintenance operation areas of highways (NMOAH). Aerial video data were obtained from an NMOAH in Chongqing, China, and vehicle trajectory data were extracted using Tracker software. The traffic flow characteristics within the NMOAH were analyzed. Subsequently, time- and energy-based surrogate measures of safety were constructed to explore the spatial distribution characteristics of accident risks in NMOAH and their correlation with traffic parameters (volume, car-following). Finally, the evolution of individual vehicle risks within NMOAH was explored. The results indicate that rear-end crashes mainly occur within 75–175 m while lane-changing crashes primarily happen within 30–125 m. Higher potential crash energy loss (PCEL) is focused on the 100–250 m range. At traffic volumes of 1,200–1,300 pcu/h, individual vehicles in the 125–175 m range are highly prone to rear-end crashes with potentially severe post-crash consequences. It is hoped that these findings can assist in formulating safety management measures for NMOAH, which is important to enhancing the safety level of NMOAH.