Different Network Performance Measuresin a Multi-Objective Traffic Assignment Problem

Traffic assignment algorithms are used to determine possible use of paths between origin-destination pairs and predicttraffic flow in network links. One of the main deficiencies of ordinary traffic assignment methods is that in mostof them one measure (mostly travel time) is usually included in objective function, and other effective performancemeasures in traffic assignment are not considered. The current study is an endeavor to introduce a solution for thisproblem by applying a multi-objective optimization idea to traffic assignment models. To do this, a problem with threeobjective functions including travel time, total traveled distance and the rates of cabin monoxide emissions are studiedfirst, and then problem with two objectives combining two well-known assignment approaches i.e. user equilibriumand system optimal is introduced. Using the weighting method to solve the multi-objective problem, and comparingthe results, show that the analytical relationships resulted from weighting method is applicable to different networks.Furthermore, comparison of both multi-objective and single-objective problems (travel time only) showed that theresults of proposed model are more appropriate in terms of having a plenary view to this issue, and thus more useful.

Keywords:

Multi-objective optimization , traffic assignment , Pareto optimal solution , user equilibrium , system optimization