A novel approach to developing organized multi-speed evacuation plans

Cities are becoming more vulnerable to all kinds of hazards or events, especially with the unpredictable impacts of global climate change. All these trends provide an urgent need for the development of comprehensive and efficient contingency plans in urban spaces. Evacuation plans are important solutions to protect people from unforeseen effects of disasters. However, evacuees’ speed differences have been ignored or little considered among most of the existing research on developing organized evacuation plans. This article presents a novel approach to planning a multi-speed evacuation. The objective is to minimize the whole network clearance time. Evacuees are grouped and each group is allocated a departure time and an evacuation route in order to minimize traffic conflicts. Three scheduling strategies and four priority rules are defined for determining the departure time of evacuation groups. Experiments based on a real-world case have been conducted to validate the approach and compare the performance of these strategies and rules. The major conclusion is that, with the proposed approach, an evacuation plan can avoid traffic congestion and minimize the whole network clearance time, and the choice of scheduling strategies and priority rules should be based on practical evacuation objectives.