Road repair sequencing for disaster victim evacuation

Disaster victim evacuation is one of the most urgent disaster relief efforts in saving lives after a disaster strikes a populated area. In urban areas, candidate routes to take for evacuation are basically determined based on static hazard maps depending on the types of disasters (e.g., routes which are not in areas at risk of landslide disaster in case of a flood, or tsunami or liquefaction in case of an earthquake). However, when a large-scale disaster occurs, unpredictable simultaneous road closures on a road network may be caused by various factors such as broken roads, traffic accidents, building collapse and outage of traffic lights by electricity failure. Since it takes time to repair roads and required resources for repairing activities are usually limited, it is necessary to determine a plan to sequence roads repairs. The plan on repairing damaged roads affects decisively how quickly and reliably evacuation is completed. To determine the optimal plan, we use stochastic time Petri nets to sequence one road repair after another for multiple evacuation origin-destination pairs with different speeds on different routes.