Performance of Traffic Networks during Multimodal Evacuations: Simulation-Based Assessment

Abstract

Mass evacuations of urbanized areas can be expected to generate traffic demand significantly in excess of routine daily travel conditions. Depending on the nature of the hazard and the population characteristics within the threat area, the elevated demand conditions may last for several days and can impact thousands of miles of roads. This paper presents the results of a project to evaluate the impact of a transit bus-based evacuation on the operation of a regional road network during a mass evacuation. In the project, the TRANSIMS agent-based simulation system was used to model the Citizen-Assisted Evacuation Plan (CAEP) for the City of New Orleans within the context of a general evacuation. Regional plans developed by Louisiana officials to support the evacuation of low-mobility individuals when under threat of hurricanes were used to code the model. However, because these plans have yet to be fully implemented, their benefits, effect on the overall evacuation operation, and the adequacy of the service they will provide has not been evaluated. In this the operational traffic characteristics of the busses and other vehicles involved in the evacuation operation were simulated under a range of conditions. The results showed that while the CAEP busses were able to increase the total number of people evacuated from the threat area, the additional vehicles had a minimal impact when they were routed exclusively to arterial evacuation routes. However, when bussed were routed to more heavily utilized freeways, travel delays increased and congestion queues increased by about 50 percent.