Part 1 of this article was originally published in edition 41 of Port Technology International.
Determination of a container terminal capacity A system working on the lowest level of detail does not consider the operation system the terminal uses. The capacity of a container terminal is limited by the capacity of the container stacking area and the quay. The latter is limited by its length and by the capacity of the ship-to-shore cranes available. The aim of such a system is to surmise the current point at which the terminal bottlenecks. With this, the user can determine how much throughput the terminal handles through use of the existing facilities, as well as the maximum possible capacity of a planned terminal. Does the bottleneck occur by the quay respective of the number or type of ship-to-shore cranes? Or does it take place in the stacking area? And how much throughput can a terminal handle with its existing capacity?
CAPS (see Figure 1) is one example for the above explained proceedings: In the input module, the model asks for general information, land side and quay side information. For simulation the system needs information on both the yearly throughput, which has to be investigated, and its distribution over the year, in order to simulate peak times. The number of container slots available has to be entered as well as the container dwell times regarding individual container types. Among other features, CAPS provides the options to develop several vessel types for the quayside definition, to design the quay in any desired configuration and to distribute the ship-toshore cranes along the quay.
After simulation, such a model evaluates the quay as well as the stacking area and provides information about the utilisation of the quay and the crane performance. The user is informed, e.g. if the quay length fits to handle a definite container volume and how many ship-to-shore cranes are necessary to serve the arriving vessels. For the area evaluation, the model ideally distinguishes various area types (e.g. areas to stack standard, reefer, dangerous, and empty containers) and it provides an indication of the sufficient number of stacking slots.
The CAPS system has been in operational use since the end of 2001. Since then, several consultancy projects have been carried out with the aid of this system. During these projects the software was enhanced and ver ified according to real operations, i.e. together with the terminal operators a simulation scenario of the current situation of the terminal was defined and the simulation results were compared with the real data of the terminal.