Control of vehicle dispatching on a cyclic route serving trucking terminals

In the less-than-truckload industry, it is commonplace to designate specific routes for tractors and drivers that remain in effect over extended time periods, lasting weeks or months. On a day-to-day basis, however, the number of tractors traveling on a route can vary in relation to demand. In this paper, we study routes that consist of two or more segments and two or more stops that define a cyclic tour for a tractor/driver team. At each stop, the driver/tractor can drop off one or more trailers, and pick up one or more trailers. The paper develops control rules based on predicted route productivity to determine when to release a tractor. The approximation is accurate when loops are relatively short, when the number of tractors traveling on a loop at any time is small, or when the productivity achieved is large. In other instances, the approximation can be used to guide the release of tractors, following a policy that adapts to calculated biases.