Article ID: | iaor20011340 |
Country: | United States |
Volume: | 47 |
Issue: | 5 |
Start Page Number: | 675 |
End Page Number: | 692 |
Publication Date: | Sep 1999 |
Journal: | Operations Research |
Authors: | Gans Noah, Ryzin Garrett Van |
Keywords: | transportation: road |
We analyze a general model of dynamic vehicle dispatching systems in which congestion is the primary measure of performance. In the model, a finite collection of tours are dynamically dispatched to deliver loads that arrive randomly over time. A load waits in queue until it is assigned to a tour. This representation, which is analogous to classical set-covering models, can be used to study a variety of dynamic routing and load consolidation problems. We characterize the optimal work in the system in heavy traffic using a lower bound from our earlier work and an upper bound which is based on a simple batching policy. These results give considerable insight into how various parameters of the problem affect system congestion. In addition, our analysis suggests a practical heuristic which, in simulation experiments, significantly outperforms more conventional dispatching policies. The heuristic uses a few simple principles to control congestion, principles which can be easily incorporated within classical, static routing algorithms.