Analysis and modeling of simultaneous and staged emergency evacuations

Disaster response in areas of high population density is centered on efficient evacuation of people and/or goods. Developing evacuation plans suitable for different levels of urgency based on the intensity of threat is a challenging task. In this study, mathematical models are developed for estimating evacuation time and delay. Evacuation time is the duration required for evacuating all vehicles from a designated region, whereas delay includes queuing and moving delays. The relationship between delay and evacuation time is investigated, and the impact of staged evacuation against simultaneous evacuation is analyzed. An example is provided to demonstrate the applicability of the developed model. A numerical method is adopted to determine the optimal number of evacuation stages. Sensitivity analysis of parameters (e.g., demand density, access flow rate, and evacuation route length) affecting evacuation time and delay is conducted. Results indicate that evacuation time and delay can be significantly reduced if staged evacuation is appropriately implemented.