Multi-modal Inter-regional Travel Demand Estimation

Since the passage of the Intermodal Surface Transportation Efficiency Act (ISTEA) in 1991, a significant number of state highway agencies have started to develop and implement statewide travel demand models to meet policy and legislative development needs. Current and future multimodal freight flows are available from the Freight Analysis Framework (FAF), to analyze national freight policy. On the passenger travel front, however, multimodal inter-regional travel demand data are still lacking while most statewide models fail to model the long-distance trips. The lack of this multimodal passenger inter-regional travel demand data limits the ability to conduct quantitative analysis for infrastructure investment and operational effectiveness needs at the national/statewide level. Drawing from previous academic research and practical projects around the world, this paper reviews several methodologies for multimodal inter-regional travel demand estimation at the national level. This international research scan is also crucial for the development of statewide travel demand models by supplementing all the currently available syntheses of domestic practices with a more international scope. The nations with their models reviewed by this paper share many similarities with a typical U.S. state, such as population, geographical scale, and the need for studying long-distance trips and other policy-oriented analyses, which further adds up the necessity of this review. Alternative approaches toward a national/statewide multi-modal inter-regional travel analysis tool, as well as the data limitations and improvement strategies are discussed.