Abstract: Rainstorms can disrupt the normal functioning of urban transportation systems and increase the time needed for emergency responses. While most existing research focuses on the impacts of 2-hour design rainfalls on urban road networks, it often overlooks the possible effects of unprecedented events with long duration and high intensity. In July 2023, a rare heavy rainstorm hit Beijing and caused severe loss. This study combined urban flood modeling with dynamic traffic routing analysis to evaluate the impacts exerted by this event on the travel times of residents in Tongzhou District seeking emergency shelters and hospitals through city roads. The results indicate that:(1)This rare rainstorm event can increase the travel time for most residents by 20 minutes; (2)Both short-term high rainfall intensity and prior excessive rainwater accumulation can significantly slow down the recovery of urban transportation systems and further amplify the rainstorm-induced flood risks. Thus, when analyzing urban flood risks, it is necessary to give comprehensive consideration to both sudden and progressive failures caused by short-term heavy and long-duration rainfall events, respectively. This insight can further inform the enhancement of flood risk management and emergency resource allocation during extreme rainstorm events.