Managed gating control strategy for emergency evacuation

This study developed a nonlinear programing optimization model to demonstrate the effectiveness of a gating control strategy for traffic operations in emergency management when the population within an affected subarea must be evacuated. Selected nodes and links on or near the subarea boundary with enhanced traffic access and flow capacities could be treated as gates for evacuation traffic to be guided through with a higher priority over the non-gate nodes/links. The objective function was to minimize the total travel cost and the total number of traffic conflicts for different control scenarios in the evacuation network. The effectiveness of the strategy was tested by using a small scale evacuation network with eight nodes and sixteen links, and then in a case study of a realistic evacuation network in the Gulf Coast area with nodes and links in multiple counties. The experimental study results showed that the gating control strategy could improve the performance of the evacuation by reducing the average travel time in evacuation trip routes and decreasing the number of conflicting traffic movements compared with an otherwise situation where evacuation trips are conducted based on ‘shortest paths’ without a gating control strategy.