Simulation of Operating Processes and Infrastructural Changes in the Upper Mississippi Navigation System
Douglas Smith, Donald Sweeney, James Campbell and Robert Nauss
Business and Industry Symposium (BIS 08)
Crowne Plaza Ottawa Hotel, Ottawa, Canada, April 14-17, 2008
Summary
This paper discusses the construction and application of a discrete-event simulation model to investigate the effects of proposed operational policies and infrastructural changes for a major inland waterway transportation system. The model is applied to a section of the river in which a series of locks create a seasonal bottleneck for commercial barge operations. Traffic scheduling rules are derived from a mixed-integer programming model designed to clear queues of waiting vessels with the smallest total waiting time and the stochastic system is then analyzed with the simulation model. Simulation results, in conjunction with historical data, reveal self-regulating behavior in the system and show how small-scale infrastructural improvements dramatically dominate local scheduling rules in their capacity to reduce traffic delays. The model reveals time-varying changes in performance under different traffic levels and the point at which major infrastructural improvements in the transportation system are required. It reveals how stochastic phenomena (variations in activity times and traffic mixes) tend to mute the benefits of scheduling strategies inferred from deterministic optimizing models. The simulation model shows the impact of alternative priority scheduling rules on different users of the waterway system and reveals a further muting of estimated benefits from changes in scheduling practices and infrastructure improvements, as queue disciplines and operating practices are modeled with greater realism than typically employed in the published literature.
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