Analysis of Near-Optimal Evacuation Instructions

In this paper, approximations of optimal evacuation instructions are analyzed. The instructions, consisting of a departure time, a destination, and a route, are for the evacuation by car of a population of a region threatened by a hazard. An optimization method presented in earlier research is applied on three different hazard scenarios resulting in an instruction set for each scenario. These instruction sets are different because of network degeneration caused by the different hazard scenarios. Analysis of the network occupancy during the evacuations as consequence of the instruction sets shows that the capacity is used in the scenarios for minimal 87%, 90%, and 87% for the period wherein the effect of the network degeneration is relatively small. Although the results are logical, no clear patterns are perceptible in the instructions leading to this network occupancy. This endorses to the viewpoint from the earlier paper, namely, that is useful to apply an optimization method to create evacuation instructions instead of applying instructions set up by straightforward rules (like evacuating to the nearest destination). Furthermore, it shows the efficiency of this specific optimization method. (C) 2010 Published by Elsevier Ltd