Evacuation Planning of Large Buildings Using Ladders

Abstract

AbstractEvacuation planning of a building in case of an emergency has been widely discussed in literature. Most of the existing approaches consider a building as a static graph with fixed, predefined exits. However, in severe disaster situations, it is desirable to create additional exits for evacuation purposes. A simple and practical way of creating additional exits is to place ladders at those locations that can reduce evacuation time effectively. For large buildings, finding optimal locations for a limited number of available ladders to utilize them effectively is not possible without using any systematic approach.In this paper, we first show that the problem of finding optimal locations for a given number of ladders among all feasible locations to minimize either the average evacuation time or evacuation egress time is NP-hard. The feasible locations for ladders are referred as dynamic exit points and the exits created by ladders are referred as “dynamic exits”. Next, we propose a heuristic for placing a given number of ladders at dynamic exit points based on the distribution of evacuees in the building. We extend the existing capacity constrained route planner (CCRP) algorithm for dynamic exit based evacuation planning.Our model is illustrated by performing a set of experiments and comparing it with existing optimization models that minimize either the average evacuation time or the evacuation egress time. The results show that the proposed heuristic produces close to the optimal solution and has significantly less computational cost as compared to the optimization models.KeywordsEvacuation planningRouting and schedulingDynamic ExitsBuilding network