Every container terminal uses three main resources: yard, machines, and people. The efficient use of these resources is the basis for granting customers the service level they are entitled to. Moreover, the more efficiently a terminal can use its resources, the more profit can be generated for the shareholders. This article focuses on the yard, one of the main resources, and more specifically on how to deal with fluctuating volumes on a densely stacked terminal.
The yard can be regarded as an intermediate stacking area, holding boxes until they are transpor ted to their next destination. Stacking boxes takes up one of the terminal’s most valuable resources: yard space.
A yard management system will position a container in a slot where, ideally, it does not need to be re-handled before leaving the terminal. After all, reshuffling containers is a very costly activity, both in time and resources, which is (usually) not billable to a customer.
The yard is a highly dynamic and constantly changing area that needs to be treated as such. Any Container Terminal System (CTS) that considers the yard as static will put constraints on the efficiency that could be obtained. Static planning requires preplanning. This means that for example for the import boxes on an inbound vessel, yard positions will be planned before the vessel arrives at the terminal. Consequently, parts of the terminal will be reserved for the boxes on this vessel. This reserved area will thus be shut off for operations and cannot be used until the discharge of the arriving vessel starts. As a result important constraints will be imposed on the available space, leaving not a lot of room for flexibility.
Real-time dynamic planning
Real-time dynamic planning will use the yard as it needs to be used. Before operations start dispatchers determine how the yard planning has to respond during operations, but no container is actually planned until the moment it physically arrives at the terminal.
Planners define the business rules. They will be used during the actual operations to obtain the ideal positions, so that containers will not need to be handled before the next operation. How these rules will be set depends on the nature of the terminal (mainly import or export, transshipment…) and the management’s preferences. These rules should not only take into account the dimension ‘space’, but also the dimension ‘time’.
Specific software features allow the dispatchers to test the rules set up for import boxes. By running the boxes contained in the bay plan coming in through the CTS, the system will tell the dispatcher if any, and which boxes will not be planned automatically. The outcome of this simulation will allow the dispatcher to adapt the rules in order to prevent boxes in need of manual planning during the actual operations.