Improved Solution Algorithm for Multicommodity Continuous Distribution and Assignment Model

Abstract

Consider a city, with multiple regional activity centers (RACs), in which the locations of traveler demand are continually dispersed. The total demand generated from a particular location in the city is fixed, but the demands from this location to the RACs are subject to a distribution function with respect to the relative transportation cost to each RAC. We take into account the cost of transportation in characterizing travelers’ choices. The congestion effect is explicitly built into the model by using a flow- and location-dependent transportation cost function. The routing behavior of travelers in the city and the user equilibrium choices of RACs are modeled by constructing a spatial user equilibrium flow pattern. The problem is formulated as a combined distribution and assignment model. A solution algorithm that is improvement upon a previously adopted iterative algorithm between the distribution function for the choice of RAC and a mixed finite-element method for route choices is proposed to solve the resultant continuous problem. A numerical example is given to demonstrate the superiority of the improved algorithm.