Optimization of Evacuation Traffic Flow Distribution Based on Road Fundamental Diagram

The spatial distribution of evacuation traffic may be unbalanced because there are many factors such as rumor, imperfect information, and personal preference, that may impact the destination choice of evacuees. Consequently, some roads may be over-saturated while other roads are not fully utilized. Such phenomenon lead to “Liebig’s barrel” that the slowest evacuation flow negatively influences the efficiency of evacuation since it prolongs the clearance time. In this paper, we focus on the optimization of traffic flow distribution in space. First, we define evacuation exits as specific roads between origin and destination of evacuation traffic. Then, according to speed-flow relationship derived from fundamental diagrams at every evacuation exit, we propose an evacuation destination choice model. Finally, a case study is conducted to validate the method. Results of the case study demonstrate that this method is able to reduce clearance time and improve average travel speed for vehicles during mass evacuation.