EVITA: An integral evolutionary methodology for the inventory and transportation problem

Abstract

The Inventory and Transportation Problem (ITP) can be seen as a generalisation of the Periodic Vehicle Routing Problem that takes into consideration the inventory costs, plus a set of delivery frequencies instead of a single delivery frequency for each shop. Additionally, the ITP can also be viewed as a generalisation of the Inventory Routing Problem to the multiproduct case. EVITA, standing for Ev olutionary I nventory and T ransportation A lgorithm, is a two-level methodology designed to address this problem. The top level uses an evolutionary algorithm to obtain delivery patterns for each shop on a weekly basis so as to minimise the inventory costs, while the bottom level solves the Vehicle Rou ting Problem (VRP) for every day in order to obtain the transport costs associated to a particular set of patterns. Here we compare four different algorithms that have been employed in the literature for solving the VRP and show how the choice of the lower level algorithm (the VRP solver) can play a significant part in the performance of the whole algorithm. © 2009 Springer-Verlag Berlin Heidelberg.