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How to … implement a new VRP Evaluator

Goals

One way to implement a new VPR variant is by extending the VRPEvaluator. This is a suitable possibility if the VRP variant does not require additional model data or decision variables. A VRPEvaluator is responsible for evaluating a solution candidate which contains a set of tours. By extending the VRPEvaluator, it is possible to interpret the available information of a specific problem instance differently.

After this tutorial you will be able to implement your own VRP variants that only require extending the VRPEvaluator. You will also have a basic understanding of the concepts and architecture concerning the VRPEvaluator and related components.

The Pollution-Routing Problem

To demonstrate the procedure of extending a VRPEvaluator, the implementation of the ​Pollution-Routing Problem is demonstrated. The Pollution-Routing Problem (PRP) considers the environmental impact of transport logistic by taking the energy consumption of a vehicle into account. Depending on the PRP model, different factors like vehicle mass, speed and environment related factors are considered.

In this tutorial the PRP is based on the Capacitated Vehicle Routing Problem (CVRP). To keep the tutorial as simple as possible only the current mass of a vehicle is considered. The current mass of a vehicle is computable by its current position in a tour. Therefore no additional model data is required and the implementation of the PRP is possible by only extending the VRPEvaluator.