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A qualitative evaluation of automated stack design principles: 1-track vs. 2-track configurations

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Author(s): Anko Nagel, Legana Consultancy B.V., Hendrik Ido Ambacht, Netherlands

It took some time for automated container handling to come to life. ECT, the forerunner in this type of container handling, commissioned its first automated container handling facility in 1992. The terminal was characterised by automated stacking and automated container transport between stack and quay. About 10 years later HHLA’s CTA facility in Hamburg was commissioned. This CTA facility has the same level of automation. For a few years now, interest in automated handling, and especially in automated stacking, has picked up and several projects are now under construction and will be commissioned within a year. Other projects are in the planning stage.

In the majority of these projects only the stack will be automated. Automated transport remains a bridge too far for most terminals. The author was deeply involved in  the developments that took place at ECT and since than has been involved in many other automated container handling projects. In recent projects some interesting distinctions in the various automated stack configurations became apparent. Most eye catching is the distinction between 1-track and 2-track configurations. A qualitative comparison of these designs is the topic of this article.

Terminals under construction with automated stacks

The existing ECT ter minal in Rotterdam uses a stack arrangement with one RMG on a track that spans six rows of containers. This will be called the 1 RMG/ 6 W(ide)/  single track configuration. This configuration was chosen because of its simplicity. At the start of the development (1987, contract with SeaLand), this was a giant leap forward in container handling. Of course the single crane arrangement was being recognised as a redundancy threat. For that reason ECT uses a diesel-electric ‘rescue-RMG’ which can be put on the track with relative ease to assist in case of a serious RMG failure (see Figure 1). It is no big surprise that the next  development was to cope with this redundancy threat in a more permanent way by permanently putting more RMGs on one block of containers.

The CTA terminal in Hamburg, commissioned in 2002, has an arrangement of two RMGs spanning 10 rows of containers. Surprisingly however, each of these RMGs has its own track and the size of one crane of the pair is such that the other one can pass underneath. RMG height at CTA is “1 over 4” (see Figure 2). For easy reference this configuration will be called: 2 RMG’s/ 10W/ 2 tracks. In Rotterdam the Euromax terminal is now nearing its commissioning date. This terminal will use a 2 RMG/10W/1 track configuration. Also the new APM terminal in Portsmouth, Virginia USA, will start operations soon. This terminal has an automated stack of 2 RMG’s/8W/1 track configuration.

In Antwerp a pilot facility with a 2 RMGs/9W/1 track configuration is now undergoing tests. In Hamburg the redevelopment of the  Container Terminal Burchardkai (CTB) is underway and the automated stack will be of the configuration 3 RMGs/10W/2 tracks. In this configuration one of the three cranes is of such dimensions that the other two can pass underneath. The track widths are the same as in the CTA terminal (see Figure 2). However, the stacking  height of the RMGs will be ‘1 over 5.’

1- or 2-track configurations, which will be the most favoured?

As can be seen from the mentioned projects there is a wide variety of configurations. The width, length and maximum stacking height will dictate the stacking capacity per block. The most important terminal characteristics such as: the dwell time of the containers, the TEU factor and the required handling speed will dictate how many hooks (spreaders) will be needed to stack and retrieve the containers. This is the reason for the variety in number of RMGs per TEU stacking slot. There has to be a balance between the storage capacity of the block and the performance potential of the RMGs on the block, both at landside as well as at waterside.


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Edition 34

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