Proposed Validation and Sensitivity Testing of Denver Region Activity-Based Models

In 1997, the Denver Regional Council of Governments (DRCOG) initiated the collection of travel survey data to update its traditional four-step travel model and for the longer-term development of state-of-the-art modeling techniques. The “refresh” of the traditional model using these data took place from 2002 to 2004 and included model component validation, validation to the 1997 base year, and validation to travel conditions in 2001. As with its current trip-based model, DRCOG is committed to rigorous validation and sensitivity testing of its activity-based modeling (ABM) system that will be developed over the next 18 months. The system is designed to make use of the most recent developments in ABM theory to better represent the travel decision-making process and provide reasonable sensitivity to a wider range of future travel options and constraints. The downfall is that there are a number of places where the models can fail. DRCOG has addressed this concern by committing approximately the same budget to the validation and sensitivity testing of the ABM that it committed to the entire refresh of the existing traditional four-step travel model. Because the ABM development process for the Denver region has just begun, this paper focuses on the initial plans for the validation and sensitivity testing of the models.