An Urban Evacuation Problem

In this chapter, linear mixed-integer urban evacuation models are presented. The assumption of the presented evacuation problem in this chapter is that every evacuee has the possibility to self-evacuate, i.e. all evacuees can leave the evacuation zone by vehicle. Hence a single commodity dynamic network flow model is considered. In order to capture the progress of an evacuation, discrete dynamic network flow models are used that force the evacuees to leave the evacuation area with respect to certain objectives within the considered time horizon. Because of the dynamic flow problem the time-expanded network of the detailed network is considered, i.e. every node is copied for every point in time and arcs connect the time-copies of nodes depending on the associated travel-time. For the purpose of restructuring the traffic routing we will use the following traffic management ideas: the reversal of lanes, the prohibition of crossing conflicts of lanes within intersections and the limitation of the number of merging lanes within intersections. Crossing conflicts will be prohibited and merging will be restricted within intersections in all models, but we will consider models that allow a two-way assignment of lanes and models that allow just the assignment of one-way streets.