Analytical methods for combining the steps of the sequential travel forecasting procedure have gained more interest in recent years. To overcome deficiencies of the sequential transportation planning approach this study applies a combined model for the simultaneous prediction of trip distribution and trip assignment. The proposed combined model can itself be reformulated as an equivalent minimization problem (EMP). It can be shown that under mild assumptions on the demand and link cost functions, the EMP is a convex programming problem with linear constraints, which has a great advantage from the computational aspects. When applying the Evans algorithm to the equilibrium problems, the model is expected to be usable in a realisticapplication within a reasonable time period. The objective of this paper is to compare the conventional sequential procedure and simultaneous combined models by applying both models to a large urban transportation networkfor captive (e.g., work, school) trip purposes. Several evaluation measures were utilized to compare the results and confirm that the proposed combined model can efficiently satisfy several convergence criterions. It became clear that the user equilibrium assignment in the proposed combined model can be obtained relatively faster than the sequential model and can beefficiently used in large transportation networks. Furthermore, the comparing results suggest that the performance of the combined model is significantly better than conventional sequential procedure.
Abstract