Integrated simulation method for waterlogging and traffic congestion under urban rainstorms

Heavy rainstorms are increasingly frequent events in urban areas. Urban rainstorms lead to road waterlogging and low visibility, which affect drivers' behavior and can thus cause traffic congestion and potential accidents. It is important to study the mechanisms of waterlogging and traffic congestion caused by rainstorms to more effectively predict them and reduce losses. In this paper, an integrated simulation method to analyze the influence of urban rainstorms on waterlogging and traffic congestion was developed. Firstly, waterlogging simulation was conducted to predict the spatiotemporal distribution of water depth on roads based on an urban storm water model. Secondly, psychological questionnaires were distributed to study the drivers' behavior during a rainstorm. Based on the psychological questionnaires' results, the vehicles' speed was estimated under different water depth and visibility conditions. Finally, a microscopic traffic simulation was carried out to predict the traffic condition using the results of the previous two parts. Case studies were conducted on a simplified road model. The effects of different parameters on waterlogging and traffic congestion were analyzed. Then the method was applied to an actual urban area in Beijing, and a detailed waterlogging situation and traffic situation were obtained. Alternate future scenarios of adding drains to mitigate waterlogging and traffic congestion during heavy rainstorms were simulated, and the method's potential to assist in decision making for urban drainage system design was shown. The integrated simulation method is helpful for early warning and risk management of urban rainstorms on waterlogging and traffic congestion.