Issues in Expanding the Denver Regional Activity-Based Model for Statewide Modeling in Colorado

This paper discusses the activity- and tour-based model developed for the Denver Regional Council of Governments in Colorado with respect to two major issues that underlie its expansion to a statewide travel model: managing short- and long-distance travel within a single model and accounting for overnight travel. In a statewide model, the issues are interconnected to the modeling of closed and nonclosed tours. Closed tours are those that begin and end at the same location during the travel day (i.e., home). Although nonclosed tours typically are not modeled in regional activity- and tour-based models, or they are modeled with relatively simple procedures, they are more important in statewide models to accommodate overnight travel. Some long-distance travel involves an overnight stay at a location other than the traveler’s home. Such nonclosed tours, which begin or end the day at a location other than home, must be modeled explicitly in a statewide model. In this paper, required adjustments are identified for key activity- and tour-based model components, and the impacts of the explicit modeling of nonclosed tours for the tour mode choice model are presented.