Evaluation of “Hot Spots” for Pedestrian Risk Assessment and Mitigation in Flood Prone Historic Built Environments

Pedestrian safety in flood-prone built environments is a significant challenge, especially when extreme events occur in areas without effective structural measures. Historic Built Environments (HBEs) are critical scenarios due to their complex layouts, high tourist presence, and limited risk-mitigation strategies. This work proposes a simulation-based approach to support decision-makers for effective evacuation planning towards the identification of HBE “hot spots” in emergency scenarios and the definition of suitable mitigation strategies for pedestrians, such as deployment of safety devices, street furniture, and risk/wayfinding signage. A parametric HBE scenario, featuring a river and a grid-like street network, is employed to simulate evacuation dynamics under consolidated environmental conditions (i.e. hydrodynamic effects) and pedestrian behaviors (i.e., pursuing the optimal evacuation strategy). Usage patterns provide information on “hot spot” requiring safety interventions based on critical floodwater-pedestrian interactions, as well as on the pedestrian individual vulnerability depending on age. Findings highlight that streets parallel to the river flow are more suitable to host shelters, as they benefit from building screening, while crossroads and street perpendicular to the river flow are priority areas for installing urban furniture and signage to improve pedestrian stability and wayfinding/decision-making. Furthermore, large squares could be equipped with raised platforms and sidewalks allowing pedestrian practicability, given the potential for high water depths in case of extreme events. This approach advances current methodologies by linking pedestrian dynamics with mapping floodwater hazard and users’ vulnerability, providing insights at the HBE open spaces scale, and a comprehensive framework for improving resilience in safer, more adaptive HBEs.