Analysis of travel mode and departure time choice for urban shopping trips

Travel mode and departure time choice of urban trips are important determinants of urban travel demand and the temporal distribution of this demand. While mode choice has received substantial attention in travel demand modeling, relatively little attention has been directed toward departure time choice. Further, the work trip has been the focus of most earlier mode choice research, and almost all earlier departure time choice research. The current paper examines the joint nature of mode and departure time choice for urban shopping trips. The model formulation in the paper adopts a nested structure with mode choice at the higher level of the hierarchy and departure time choice at the lower level. A multinomial logit (MNL) form is used for modeling mode choice and an ordered generalized extreme value (OGEV) form, which recognizes the natural temporal ordering of the departure time alternatives, is adopted for departure time choice. The proposed MNL-OGEV model is applied to data obtained from the 1990 San Francisco Bay area travel survey and is found to perform better than the MNL and nested logit models. In addition, the results indicate that the MNL and nested logit models lead to biased level-of-service estimates and to inappropriate policy evaluations of transportation control measures in the current empirical context.