Short-Notice Bus-Based Evacuation under Dynamic Demand Conditions

Abstract

In the literature on bus-based evacuation planning for short-notice evacuations, researchers have assumed either a known fixed number of evacuees or a single bus trip to the shelter on specified evacuation routes, or both of these constraints. These constraints distance their models from real-world situations, where evacuees continuously arrive at pickup points and multiple bus trips are required for the economical use of a limited number of buses. In this study, a bus-based evacuation model has been proposed to evacuate a known number of total evacuees who arrive at pickup points continuously. Evacuees are placed in shelters using multiple trips of the available buses with flexible route options. Furthermore, using the model, efforts have been made to investigate the factors affecting bus-trip assignment through a case study of flood evacuation planning for Kawajima Town in Saitama Prefecture. Two cases with warning times of 90 min and 60 min are presented. The overall bus capacity for trips to the shelter was observed to be 90−96%, which indicated the model's efficient performance when modeling multiple trips.