The vehicle routing and scheduling problem has been studied with much interest within the last four decades. In this paper, some of the existing literature dealing with routing and scheduling problems with environmental issues is reviewed, and a description is provided of the problems that have been investigated and how they are treated using combinatorial optimization tools.
In @cite_54 , the authors propose a heuristic two-phase solution procedure for the dial-a-ride problem with two objectives. The first phase consists of an iterated variable neighborhood search-based heuristic, generating approximate weighted sum solutions and the second phase is a path relinking module, computing additional efficient solutions.
@cite_54
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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 e-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