Evaluation of Network Preloads on a Medium-Sized Urban Travel Forecast Model

Transportation engineers and planners attempt to understand urban travel characteristics to develop, formulate, and analyze problems and opportunities better. Transportation professionals use urban transportation models and typically implemented the four-step urban transportation planning process. This study examined a modified planning process that preassigned external trips to the transportation network before distributing and assigning internal trips. The preassignment, or preloading, of external trips helped to ensure that trips passing through the network were assigned to only the major through routes and that internal trips were modeled with the knowledge that external trips were present on the roadways before selecting destination or route. The study concluded that the preload methodology did not affect the validity of a travel model in a medium-sized urban travel forecast model and reduced assignment error on minor arterial roadways, which would not be the typical routes used by external travelers, to a level below the maximum deviation where an incorrect decision would be made regarding improvements to the roadway infrastructure.