Location and Routing of the Defense Courier Service Aerial Network

摘要

This study extends work done by the Military Airlift Command's Analysis Group onreducing the operating costs of the Defense Courier Service aerial network. The study's primary focus is to minimize those costs by varying the number and location of servicing depots, and the routes flown from those depots. The theoretical algorithm used in the methodology is an expansion of Laporte's (1986) formulation of the multiple depot multiple travelling salesmen facility-location problem. Multiple servicing frequency is addressed by clustering co-located demands with Kulkarni's (1985) subtour breaking constraint. Vehicle range is considered by redressing a shortfall of the subtour breaking constraint, which was noted by Brondie (1988). The formulation is used as a validation of a system wide solution heuristic, since exact solution is beyond the range of current computing. The solution heuristic is a combination of the minimum spanning forest (Prim and Dijkstra) and the Clark-Wright method. The spanning forest is used for depot location and partitioning, while the Clarke-Wright computes the routes flown from the depots to their assigned service points. The heuristic averaged 3.3% worse than optimal in six validation runs, with no run greater than 15.25% worse than optimal. The results indicate several depots may be closed without large increase of system mileage.