Part 1 of this article was originally published in edition 31 of Port Technology International. It is available for download at https://3.8.175.202 under journal archives. Part 2 will cover a simulation model, the results and conclusions.
Abstract for Parts 1 and 2
Container terminals are struggling with the everincreasing volumes, and are therefore searching for solutions to increase throughput capacity without expanding their physical footprint. One way is changing the stacking system itself. Another way is to increase yard density, however this typically leads to a productivity decline when exceeding cer tain occupancy rates.
The question is whether we can avoid this decline by increasing the intelligence of the grounding algorithms? Or do we need additional housekeeping for grooming up the yard? Traditional stack strategies allow for up to 60-65 per cent operational yard density, but here we are looking for achieving 85 per cent and still working atacceptable productivity levels.
In this paper, we present an approach how to develop stacking strategies that can cope with higher densities without productivity losses. We have prototyped the algor ithms in a simulation environment, and tried them out over a long period of time to be able to assess the long-term effects. We show that principles coming from automated stacking systems, as implemented in Rotterdam and Hamburg (so called controlled random stacking), can also be applied in more traditional facilities, such as RTG terminals.
Simulation model
Total terminal model
The simulation model that we have used to model the stacking strategies and assess them is a comprehensive model in the sense that all processes taking place between gate and vessel are depicted at a detailed level. Basically, the model consists of two main components: one representing the Terminal Operating System(TOS) and one representing the physical process that takes place at a terminal.
The connection between the two is quite similar to the interfaces that are in place in real operations between TOS and equipment, handhelds, and other communication devices (for instance, pedestals at gate and truck interchange).
TOS simulation
The first main component is the module in the simulation that takes care of most functionality of a typical TOS, i.e. planning, scheduling, grounding, allocation and dispatching in real-time. That means it comprises the work instructions for each piece of equipment based on the plans that result from information such as load/discharge lists, pre-arrival information, gate arrivals, train schedules, shift schedules, and so on…
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