Coupled Multi-risk Mitigation in Historical Urban Outdoor Built Environment: Preliminary Strategies Evaluation Through Typological Scenarios

Outdoor Built Environment (BE), such as squares, are paramount scenarios in historic cities. They attract many users that can be affected by both Slow and Sudden onset disasters, depending on the combination of possible hazards, BE modification in view of the BE morphological and constructive features, and the users’ vulnerability and exposure. The coupling of sudden and slow-onset disasters represents a critical but not remote situation. This work hence provides an approach to assess coupled multi-risk in historical outdoor BE by using behavioural simulation methods and to evaluate the effectiveness of mitigation strategies. The simulation model is based on a probabilistic, multi-agent and cellular automata approach, developed in a slow-to-sudden events perspective. Heatwaves (as a slow onset disaster) affect the initial users’ position in the outdoor BE in view of outdoor temperature. Then, a terrorist act (as a sudden onset disaster) appears, thus making users evacuate from the outdoor BE. The application involves relevant typological conditions of outdoor BE to trace rapid and generalisable overviews of emergency impacts that can be then verified in specific case-studies. The slow-to-sudden events approach is applied to different BE typologies characterized by different climate conditions for hazards, terrorist attacks, and mitigation strategies. Simulation analysis mainly concerns evacuation to focus on quick events faced by users. Results demonstrate the approach capabilities in comparing coupled multi-risks conditions depending on BE configurations. The approach can outline quick solutions in the considered typological BE, and can be applied to real-world scenarios to “tailor” strategies on effective BE conditions.