Optimize Evacuation Route Considering the Operational Cost as a Constraint

Evacuation planning involves modeling, operation, and management of evacuation routes before and during emergency evacuation. This paper presents the development and examination of a route optimization model which considers the operational cost as a constraint. The study is focused on the situation when the backbone evacuation route, usually the interstate highway system, is over congested and some traffic need to be directed to local street networks. As intersections are the key control components of a street network, traffic operations at intersections cannot be neglected in route selection. In order to consider the operational cost in the modeling process, a street network is first presented by an extended graph network which has cost information associated with each node. Then, a system optimal traffic assignment approach is used to select and optimize the evacuation routes. The property of the approach is examined by a numerical test which includes a network composed of a backbone interstate highway and a grid network with over 30 intersections.