Mode choice, transport structure and urban land use

A theoretical model of the urban land market is solved to examine the impact of bimodal passenger transportation on equilibrium residential land use. In this model travel to the central business district occurs on a dense system of radial roads or bus routes and a competing system or radial expressways or mass transit lines fed by a subsidiary system of densely spread access streets. Under rational behavior assumptions for households, it is shown that various basic urban forms can result depending on the relative generalized cost characteristics of the competing dense and sparse radial networks. The basic urban forms yield fundamental shapes, differing as to the relative geometry and position of the market areas for the two modes. The standard Alonso-Muth model of unimodal travel and circular urban form is found to result as a special case in several of these cases. American urbanized areas of various sizes and modal mix provide plausible examples for each of the basic forms. The paper concludes with a discussion of the model's implications as a framework for examining optimum urban transport structure and the proliferation of transport routes as a function of urban size.