Abstract
A major deficiency in current transportation planning models is their inability to handle the interaction between the quality of the transportation network and the level of demand for transportation. In trip distribution this aspect is reflected in the requirement that the number of trips generated and attracted at a zone remain constant even when the network becomes congested. Drawing on the work of Wilson some suggestions are made for a distribution model, which incorporates a degree of demand elasticity. This model has as its basis the assumption of a constant level of resource to iteration and also relates quite naturally to measures of interest in land-use prediction.