Dynamic Traffic Assignment Evaluation of Hurricane Evacuation Strategies for the Houston–Galveston, Texas, Region

The Houston–Galveston, Texas, region has experienced several major hurricanes in recent years. During the evacuation for Hurricane Rita in 2005, the Texas Department of Transportation (DOT) decided to implement contraflow operations on I-45 to relieve massive evacuee congestion departing Houston to the north. The decision to implement contraflow was a difficult one because it involved multiple jurisdictions and required extensive coordination of manpower and resources from various entities. After the Hurricane Rita experience, the Texas DOT implemented a new strategy, referred to as “evaculane,” in which evacuation traffic could use the outside paved shoulder as a traveling lane when an evacuation was under way and evaculane signing beacons were activated. The objective is to increase capacity along key evacuation routes while avoiding the need for full-scale contraflow operation whenever possible. The evaculane on I-10 was successfully put into use during the Hurricane Ike evacuation in 2008. With the widening and completion of evaculanes on I-10 and US-290 as well as a partial contraflow plan for the I-45 corridor, the Texas DOT sponsored a study to develop a decision support tool to help determine whether these strategies would adequately handle the evacuation demand for various Houston–Galveston region evacuation scenarios. This paper describes the quantitative assessment of the performance of alternative evacuation strategies using a dynamic traffic assignment model, DynusT. The evaluation results indicated the evaculanes on I-10 and US-290 can sufficiently handle high evacuation demand on both routes without contraflow operation. In addition, a partial contraflow plan for I-45 was shown to provide sufficient capacity to handle high evacuation demand in lieu of full-scale contraflow operation.