Effect of Traffic Volume in Real-Time Disaster Evacuation Guidance Using Opportunistic Communications

In case a large-scale disaster hits a big urban area, studies have been undertaken on effective disaster evacuation guidance using mobile phones of evacuees. In our previous work, we proposed a real-time disaster evacuation guidance using opportunistic communications as an application of Delay Tolerant Networking to disaster management. In the guidance, evacuees gather disaster information, such as impassable roads and dangerous areas, on their mobile phones by themselves and share it with each other using opportunistic communications between nearby phones on their evacuation routes to refuge areas. We numerically evaluated the performance of the guidance and showed that the guidance considerably reduces evacuation time. In this evaluation, however, we neglected the effect of traffic volume of evacuees, which might cause serious traffic congestion, inhibiting a smooth evacuation. In this paper, we consider the effect of traffic volume on evacuation time and numerically evaluate the performance again by introducing capacity-constrained nodes on road graphs. We show that the guidance also effectively reduces the evacuation time regardless of the traffic volume.