A PRACTICAL APPROACH TO INCORPORATE TRIP CHAINING IN URBAN TRAVEL MODELS

Most urban travel models apply some variant of the traditional four-step modeling approach: trip generation, trip distribution, mode choice, and trip assignment. The first three components are usually estimated and applied separately for several trip purposes, for example, home based work, home based other, and non home based. In reality, however, a traveler may combine trips of different purposes into one tour. Modeling trip chaining has been widely discussed in the travel demand literature, but new approaches have generally been limited to academic research. This paper describes the application of trip chaining modeling in the development of the Bench/Valley Model. This model was developed to provide updated travel forecasts for the Boise Metropolitan Area in Ada County, Idaho. The need for a state-of-the-art travel model was required for the Bench/Valley Transportation Study to obtain more accurate travel forecasts and to satisfy federal requirements, such as the Intermodal Surface Transportation Efficiency Act and the Clean Air Act Amendments.