A regional travel forecasting model system update using a 1980 data base is reported. Use of the 1981 bay area travel survey and the1980 census urban transportation planning package is described in terms of providing a data base for model estimation and validation. Historical model development efforts in the bay area are compared with current efforts. The demand model development process is characterized as a six-step process involving development of component modelsand the subsequent packaging into an aggregate forecasting system. The mtcfcast-80/81 forecasting system involved reestimation of all model components. Simplifications to the original mtcfcast system were introduced where warranted; the structure of the mobility and worktrip models was tampered with the least. In contrast, the work-tripmode choice model was expanded to distinguish between two-occupant and three-plus-occupant carpools, in support of travel forecasting for high-occupancy-vehicle lane projects. Continuity is seen as the key to maintaining and updating regional travel demand model systems.This paper appears in transportation research record no. 1220, Forecasting.
Abstract