When large-scale disasters occur, evacuees have to evacuate to safe places quickly. They, however, may not be able to afford to obtain sufficient information for their evacuations under such emergent situations. In this paper, we propose an automatic evacuation guiding scheme using evacuees' mobile nodes, e.g., smart phones. The key idea to achieve automatic evacuation guiding is implicit interactions between evacuees and their mobile nodes. Each mobile node tries to navigate its evacuee by presenting an evacuation route. At the same time, it can also trace the actual evacuation route of the evacuee as the trajectory by measuring his/her positions periodically. The proposed scheme automatically estimates blocked road segments from the difference between the presented evacuation route and the actual evacuation route, and then recalculates the alternative evacuation route. In addition, evacuees also share such information among them through direct wireless communication with other mobile nodes and that with a server via remaining communication infrastructures. Through simulation experiments, we show that 1) the proposed scheme works well when the degree of damage is high and/or road segments are continuously blocked, 2) the average evacuation time can be improved even in small penetration ratio of the proposed system, and 3) the direct wireless communication can support many evacuations at almost the same level as the communication infrastructure when the number of evacuees becomes large.

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We have proposed an automatic evacuation guiding scheme based on cooperation between evacuees and their mobile nodes. In the previous work, we assume that information about blocked road segments is shared among mobile nodes through Epidemic routing, which is a Delay Tolerant Network (DTN) routing protocol. In this paper, we propose an information sharing scheme called On-Demand Direct Delivery, which can reduce the network load compared to Epidemic routing. Since each evacuee moves to a safe place, he/she will require the information about blocked road segments in the region from the current position to the safe place. The proposed scheme selectively retrieves the information about blocked road segments in that region, through Direct Delivery.Through simulation experiments, we show the proposed scheme can keep the effectiveness of evacuation guiding with reduction of network load to about 1/36, compared to Epidemic routing.