Distribution and Assignment of Compulsory and Discretionary Traffic

Abstract

This paper presents the development of a combined equilibrium model for the simultaneous prediction of the destination and route choices that face suburban or rural automobile travelers. Destination choice is given by a dogit model to take into account the travel behavior of compulsory (work) and discretionary (nonwork) trips. A logit-based route-choice model was employed, with a stochastic user equilibrium principle, to develop route flows between each origin–destination pair. The natural logarithm of the denominator of the logit route-choice model (i.e., log-sum) was computed and fed back into the destination-choice step. Under this iterative process, the destination choice for discretionary trips responded to changing travel-cost conditions, whereas the destination choice for compulsory trips remained fixed in the study time period. The proposed combined destination- and route-choice (CDR) model can itself be reformulated as an equivalent convex programming problem with linear constraints, a great advantage from a computational perspective. The CDR model was applied empirically to a county-level network in New Jersey. The results encourage further applications of the CDR model to large-scale networks.