Node aggregation in vehicle routing

We describe a special variant of the Vehicle Routing Problem (VRP), where there are many customers per road segment. Ametaheuristic tabu search algorithm for the VRP is given, and aggregation of customers is used to better the performance,with respect to both time and solution quality. The methods are tested on test instances from the literature as well as aportfolio of new test instances especially made to fit to the problem description. Test results are reported, showing that aggregation can lead to substantial improvements both in time and solution quality in this setting, especially for larger instances.