Developing Tolled-Route Demand Estimation Capabilities for Texas: Opportunities for Enhancement of Existing Models

The travel demand models developed and applied by the Transportation Planning and Programming Division (TPP) of the Texas Department of Transportation (TxDOT) are daily three-step models (i.e., trip generation, trip distribution, and traffic assignment sequentially invoked). Currently, TxDOT TPP does not have a procedure to account for existing or planned toll roads in the urban travel demand models. TxDOT TPP has been operating under guidance established when toll roads existed as planned facility improvements in either the interim or forecast year model applications. Although the larger urban areas in Texas have embraced tolled facilities for quite some time (i.e., Dallas-Fort Worth, Houston, and Austin), roads that charge users a fee to bypass congestion or provide alternative routes have only been implemented recently in a select few small to medium-sized urban areas still under the purview of TxDOT TPP model development. In order to calibrate base year travel models with operational toll roads or models with planned tolled facilities, TxDOT TPP needs a procedure to account for facilities that charge fees to the user. For the tolled facilities currently operational in small to medium-sized study areas, the fees are fixed and are not dynamic by time of day or congestion levels. The technical objective of this research report is to provide TxDOT TPP with a menu of potential procedures that could be selected for implementation in the current Texas Package suite of travel demand models to reasonably estimate toll road demand, primarily for the small to medium-sized urban areas. Nationally, generally two approaches are used: a path-based system and a choice-based system. Researchers reviewed both approaches as well as different supplemental techniques (i.e., time of day, market segmentation, and mode choice) implemented nationally and within the state that are complementary to any toll demand estimation techniques. Challenges and considerations for each of the approaches are reviewed and presented. The procedures and applications reviewed in this project are not intended to replace or compete with existing toll-financing-level analysis.