Abstract
The formulation of the modal split model employed in this paper rests upon the assumption that travellers minimize the disutility of travel. The disutility function is a function of the various attributes of travelling by different modes such as the elapsed time and the cost. Individuals are assumed to have disutility functions of identical form, differing only in the values assigned to the various parameters. There is assumed to exist a probability density function of these parameter values over the population.