Integrated districting, fleet composition, and inventory planning for a multi-retailer distribution system

摘要

We study an integrated districting, fleet composition, and inventory planning problem for a multi-retailer distribution system. In particular, we analyze the districting decisions for a set of retailers such that the retailers within the same district share truck capacity for their shipment requirements. The number of trucks of each type dedicated to a retailer district and retailer inventory planning decisions are jointly determined in a district formation problem. We provide a mixed-integer-nonlinear programming formulation for this problem and develop a column generation based heuristic approach for its set partitioning formulation. To do so, we first characterize important properties of the optimal fleet composition and inventory planning decisions for a given retailer district. Then, we utilize these properties within a branch-and-price method to solve the integrated districting, fleet composition, and inventory planning problem. A set of numerical studies demonstrates the efficiency of the solution methods discussed for the investigated subproblems. An additional set of numerical studies compares the branch-and-price method to a commercial solver and an evolutionary heuristic method. Further numerical studies illustrate the economic as well as environmental benefits of the integrated modeling approach for various settings.