Network Equilibrium Model of Employment Location and Travel Choices

Abstract

A network equilibrium model for the simultaneous prediction of employment location, trip distribution, mode choice, and trip assignment is developed. The employment location choice was given by a simplified form of Putman’s employment allocation model. The trip distribution and mode choice were formulated as a nested logit model. Trip assignment was based on Wardrop’s “user-optimized” principle. The proposed combined employment location, trip distribution, mode choice, and assignment model can itself be reformulated as an equivalent minimization problem (EMP) so that the equilibrium conditions on the network and the location and travel demand functions can be derived as the Kuhn-Tucker conditions of the EMP. Under mild assumptions on the demand and link cost functions, the EMP is a convex programming problem with linear constraints, a great advantage from the computational aspect. In addition, a unique solution of the EMP exists that is equivalent to the proposed combined model. When applying the Evans algorithm to the equilibrium problem, the model is expected to be usable in a realistic application at a reasonable cost and within a reasonable time period. Several areas for further extensions of the model are also discussed.