Trapped on the seashore, seaborne evacuation, and impact of exposure to PM2.5: Live demonstration of the urbanEXODUS large-scale evacuation model

Abstract

Wildfires can trigger large-scale pedestrian, vehicle and seaborne evacuations, and cause injuries and fatalities. Evacuation models are employed to better understand the involved processes and their interactions. During the final exercise of the European Commission’s H2020 IN-PREP project, urbanEXODUS was used within a training platform, by incident managers, to aid their response to a simulated disaster. The scenario involved a traffic accident escalating to a wildfire, causing the local community to evacuate. The model combined pedestrian and vehicle evacuation, and through a flow model, a simplistic representation of boat evacuation. The effects of wildfire on escape routes and possible fatalities were evaluated using fire perimeter data. The development of a novel fractional dose model allowed the software to determine agents’ acute exposure to PM2.5, in relation to the WHO daily mean Air Quality Guidelines (AQG). The simulation results comprise key evacuation performance parameters including evacuation times, fatalities, and escape route usage. Results indicate that 6% of the population was unable to leave the area and are treated as fatalities. The road network and boats were used by 69% and 31% of the evacuees respectively. PM2.5 exposure was zero for 84% of the evacuees, and below the AQG, for 1%, while 15% received, on average, a dosage of 7.6 times the AQG (range 1.0 – 28.3, SD = 5.8), which may cause respiratory and cardiovascular disorders. The model offers detailed evacuation information that is practically impossible to obtain otherwise, allowing crisis managers to take risk-informed decisions when planning for a crisis