A Heterogeneous Fleet Vehicle Waste Collection Problem with Various Zones and Intermediate Facilities.

Waste collection is one of the important problems that can affect urban life. A multi-zone waste collection routing problem is proposed in this paper considering intermediate facilities, depot centers and bins as network’s nodes. In this model heterogeneous fleet vehicles are considered to load wastes from bins from every zone and then unload them in disposal centers which belong to that zone and each zone can include just one depot center. A mixed integer programming model is considered to solve the problem with considering new assumptions. The objective function attempt to minimize the total operation cost of vehicles including fixed and variable costs and also minimizes the number of vehicles are used and last term of objective function is the absolute difference between the total number of unloading at each disposal center and the average number of unloading at all of the disposal centers. Finally in order to show applicability of proposed model, two small large numerical examples are presented.