Scatter search for a real-life fleet size and mix vehicle routing problem with time windows in Iran

The fleet size and mix vehicle routing problem (FSMVRP) consists of defining the type, the number of vehicles of each type, as well as the order in which to serve the customers with each vehicle when a company has to distribute goods to a set of customers geographically spread, with the objective of minimizing the total costs. In this paper, we study a real-life FSMVRP with time windows (FSMVRPTW) that occurs in a major Iranian industrial group. To find satisfying solutions to this complex problem, we propose a scatter search (SS) algorithm. Next, the solutions obtained are compared with the current vehicles and routes used actually by the company. Our results show that the total distribution cost can be reduced significantly when the proposed method is used.