A heuristic two-phase solution approach for the multi-objective dial-a-ride problem



In this article, we develop a heuristic two-phase solution procedure for the dial-a-ride problem with two objectives. Besides the minimum cost objective a client centered objective has been defined. Phase one consists of an iterated variable neighborhood search-based heuristic, generating approximate weighted sum solutions; phase two is a path relinking module, computing additional efficient solutions. Results for two sets of benchmark instances are reported. For the smaller instances, exact efficient sets are generated by means of the ϵ-constraint method. Comparison shows that the proposed two-phase method is able to generate high-quality approximations of the true Pareto frontier. © 2009 Wiley Periodicals, Inc. NETWORKS, 2009