Modeling Gate Congestion of Marine Container Terminals, Truck Waiting Cost, and Optimization

As a consequence of the continuing growth of container volume and the introduction of 13,000 containerships carrying 20-ft-equivalent-unit (TEU) containers into major trade routes, the port industry is under pressure to come up with the necessary capacity to accommodate the increasing freight volume. One critical issue is the gate capacity of marine container terminals. Limited gate capacity leads to congestion. The harbor trucking industry operates in a competitive environment, and gate congestion is detrimental to its economic well-being. This paper applies a multiserver queuing model to analyze gate congestion and to quantify the truck waiting cost. An optimization model was developed to minimize the total gate system cost with data from field observations. A case study was applied to analyze gate congestion behavior and the truck waiting cost. The sensitivity of the model is discussed. With optimization, the truck waiting cost can be drastically reduced. Several congestion mitigation alternatives can be derived from the optimization model; the use of a truck appointment system seems to be the most viable way to reduce gate congestion and increase system efficiency.