Scheduling Deliveries with Backhauls in Thailand's Cement Industry

The problem of truckload delivery with backhaul scheduling was formulated, and a methodology for ant colony optimization that was developed for a related problem, the problem of vehicle routing with backhaul and time windows, was adapted for the solution of the truckload delivery problem. The problem of truckload delivery with backhaul scheduling differs from the problem of vehicle routing with backhaul and time windows in that shipments are in units of truckloads, multiple time windows in multiple days are available for delivery to customers, limited space for servicing customers is available, and multiple visits to each customer may be required. The problem is motivated by a real-world application arising at a leading cement producer in Thailand. Experts at the cement production plant assign vehicles to cement customers and lignite mines on the basis of manual computations and experience. Mathematical and computational frameworks are provided for modeling and solving this real-world application.