Tour-Based Model Development for TxDOT: Evaluation and Transition Steps

The Texas Department of Transportation (TxDOT), in conjunction with the metropolitan planning organizations (MPOs) under its purview, oversees the travel demand model development and implementation for most of the urban areas in Texas. In these urban areas, a package of computer programs labeled as the “Texas Travel Demand Package” or the “Texas Package” is used as the decision making tool to forecast travel demand and support regional planning, project evaluation, and policy analysis efforts. The Texas Package currently adopts the widely used four step trip-based urban travel demand modeling process, which was developed in the 1960s when the focus of transportation planning was to meet long-term mobility needs through the provision of additional transportation infrastructure supply. The trip-based model was intended to provide basic, aggregate-level, long-term travel demand forecasts for long-range regional transportation plans and evaluation of major infrastructure investments. Over the past three decades, however, the supply-oriented focus of transportation planning has expanded to include the objective of evaluating a range of travel demand management strategies and policy measures to address rapidly growing transportation problems, including traffic congestion and air quality concerns. The travel demand management emphasis, combined with federal regulations, has placed additional information demands on the capabilities of travel demand models. As a result, new approaches have been developed to model and forecast travel demand. The new approaches include the tour-based modeling approach, which employs tours instead of trips as the unit of analysis. The tour-based approach enhances the behavioral realism in modeling travel demand and the abilities of travel forecasting models in assessing transportation policies and evaluating alternative transportation investments. Hence, TxDOT is considering the implementation of tour-based modeling procedures. As a first step of a potential advanced model implementation, this proposed project evaluates the feasibility of, and documents the potential benefits from, a tour-based modeling process. It documents the steps to transition toward a tour-based framework, including an evaluation of data needs, software requirements, and software enhancements, ease of implementation and application, and staffing and related resource needs.