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Vitellas Michael


2011 Diploma Thesis Title:  Load Exchange for a Vehicle Routing Problem With Dynamic Pickups

CV ( Greek Version)

The problem addressed in the present thesis, concerns a Vehicle Routing Problem with Dynamic Pickups (VRPDP). In such a problem, vehicles are destined to serve delivery requests known prior to the start of operations, and as the working plan unfolds newly arrived pickup requests are assigned to the fleet of vehicles. Solution approaches proposed by the DeOPSys lab to address this problem, allocate the dynamic requests to the most appropriate vehicles, allowing, if it‟s profitable, the change in sequence of the delivery orders of a certain vehicle. Each vehicle, however, is restricted to serve the delivery orders assigned to it at the beginning of the time horizon.
The main purpose of the current thesis was to solve the VRPDP using a novel strategy that allows transshipment of delivery orders between vehicles. This strategy leads to a holistic view of routing operations at a reoptimization period allowing each request (static or dynamic) to be served by any vehicle; therefore the strategy has the potential to provide more effective solutions, in terms of travel costs and service quality. So, the main contribution of the thesis concerns the definement of this original strategy, first proposed in the DeOPSys lab, and the implementation of Load Exchange Strategy (LES) in a VRPDP environment of two vehicles. Computational results illustrate that the proposed strategy offers superior results in many cases, improving the solutions of the previous approaches over 15% on average. The strategy investigated in this thesis may form the basis for further research in the DeOPSys laboratory.