Assessment of urban waterlogging-induced road traffic safety risk and identification of its driving factors: A case study of Beijing

Due to the increasing number of urban waterlogging events, systematic risk assessment and cause exploration are needed to ensure the safety of people's lives and property on roads. In this paper, the urban waterlogging-induced road traffic safety risk (UWRTSR) in the central part of Beijing was assessed and its driving factors were investigated. We obtained the simulation data of road inundation for five rainstorm return periods (5-year, 10-year, 20-year, 50-year and 100-year) through the InfoWorks ICM hydrodynamic model. Then, the safety risk levels of pedestrians and vehicles are evaluated with safety criteria formulas and standards, and the driving factors are identified by the Geodetector model. The results show that the proportion of the total length of road sections at different risk levels for pedestrians, stationary vehicles and moving vehicles increased with increasing rainstorm return period, while for the same road section, the risk level for pedestrians or vehicles may increase due to a higher intensity rainstorm event. The results of subsequent driving factor analysis show that slope, terrain ruggedness index (TRI) and LS factor were the top three single-factor explanatory powers, with the joint effect of slope and rain pipe capacity (RPC) possessing the largest explanatory power. It is found that a high level UWRTSR is to be generated in road sections with low drain network specifications and high slope gradients. Our research may help smooth emergency resource management, road network construction and reconstruction to mitigate the waterlogging risk.