Enhancements to travel demand models for ITS and HOV impact assessment

The purpose of this paper is to identify desirable improvements to specific components of travel demand models and to develop recommendations for specific model enhancements. These model enhancements can significantly improve travel demand model capabilities in assessing impacts resulting from the deployment of intelligent transportation systems (ITS) user services and high occupancy vehicle (HOV) lanes. One of the major concerns about travel demand models is the inability of model systems to assess large changes in transportation systems and operations being either under deployment or being contemplated for the near future including HOV lanes, ITS technologies, widespread road pricing, and fundamental changes in land use policy. Travel demand models, however, have only limited capability to accurately estimate changes in operational characteristics such as delay, speed, and queuing. Therefore, recommendations for model enhancements in this paper focus on refinements to the operational components of travel demand models including assignment and mode choice. This paper includes recommendations for model enhancements in the following areas: improved forecasting of speed, delay, and queuing; peak spreading; dynamic assignment; HOV demand modeling; HOV supply modeling; representation of traveler information, and enhanced sensitivity of emissions and fuel consumption estimation procedures.