Sequencing of Container Deliveries to Over-the Road Trucks from Yard Stacks; Final rept

摘要

Containers unloaded from ships are typically kept on the terminal ground for a short duration until they are dispatched. Such containers are transported off the terminal ground either by train or by over-the-road trucks. This project focuses on the delivery of containers to over-the-road trucks. Through the use of a specifically developed simulation tool, we examine in this study the effect of container delivery methods on the mean truck turn time, as the container volume increases. Based on our simulation experiments we show that: under continued growth the need for better sequencing of container delivery from yard stacks is inevitable; it is feasible to provide more intelligent and dynamic sequencing for the container delivery as an alternative to first-come-first-served, given the adoption of technology; intelligent sequencing rules need not be complex. Simple heuristics such as Shortest Job First, Shortest Seek Time First or Elevator algorithm can be very effective in reducing truck turn time as well as queue size; both Shortest Job First and Shortest Seek Time First have the drawback of starvation (some jobs may be continuously delayed by new arrivals). The Elevator algorithm has no such deficiency and exhibits comparable performance, thus should be preferable; even with the most rudimentary system of one-day advance appointments, the terminal would be able to perform a sufficient amount of reshuffling to enable more efficient deliveries; our simulation tool is sufficiently flexible to allow users to input parameters that reflect future condition of their terminal's operations and determine if alternative sequencing rules for container delivery warrants implementation.