A combined trip distribution and assignment model for multiple user classes

This paper presents a combined trip distribution and assignment model with multiple user classes, in which the trip productions at origins and trip attractions at destinations for each mode are available. In this model, the entropy-type (or gravity-type) trip distribution submodel is incorporated with the user equilibrium assignment problem for multiclass-user transportation networks. The original unsymmetrical link cost functions can be converted to symmetric forms by a ‘normalization’ procedure, and hence an equivalent convex mathematical programming model is formulated. Two different algorithms based on the Frank-Wolfe’s and Evans’, respectively are developed and their computational results on test networks are reported. This model is appropriate to be used on congested and multi-modal networks in which the link travel time is similar for all traffic.