Evacuation Centrality: Agile Evacuation Routing in Unpredictable Hazardous Conditions

In this paper, we study the agility of evacuation routes in relation to dynamically changing unpredictable hazardous conditions. Infrastructure safety conditions may unpredictably change through time. Due to unpredictability, evacuees’ safety can get jeopardized at any point of the evacuation route. Thus, it is not sufficient only to find the shortest evacuation route considering present safety conditions, but we should also consider other relevant characteristics that make the evacuation route sufficiently safe through time. With this aim, we propose a new node importance metric called evacuation centrality, inspired by betweenness centrality. The node evacuation centrality is a parameter that represents the importance of the node for evacuation considering the availability of alternative safe and efficient routes from that node towards safe exits. Relatedly, we propose the concept of agility of an evacuation route, which represents the ability of a route to efficiently and safely reroute from the route’s constituent nodes in case of contingencies. Given a building network with a set of evacuees’ positions and safe exits, we mathematically formulate the problem of finding agile evacuation routes. In addition, we propose a solution method for that problem. The functioning of the proposed method is demonstrated by means of a case study.