Methods for Combining Modal Split and Equilibrium Assignment Models

Two ways for combining modal split and traffic assignment techniques into simultaneous mode and route choice models are discussed. In one model, users are assumed to choose their routes according to Wardrop's equilibrium principle and their modes according to mode choice functions of the difference in modal disutility. In the other model, a route and mode choice equilibrium in which no user can change his route or mode to lessen his general disutility is assumed. The advantages and disadvantages of each of these combined models are discussed. Efficient solution techniques for the models are presented; preliminary computational testing showed excellent results. Since these techniques require successive solutions of similar traffic assignment problems, they should be applicable to realistically large problems.