Automated container handling is a recognised megatrend in the container handling industry. It started back in the early 1990s, when the ECT Delta Terminal, Rotterdam, began to use unmanned rail mounted gantry cranes in their container yard, with considerable success. The industry noticed, and investment in new automated terminals grew. Automated container handling technology developed quickly, concentrating on the cranes handling the intermediate storage of containers in the yard.
The automated rail-mounted gantry (ARMG) crane was popular from the beginning for greenfield terminals where it was advantageous to build container blocks perpendicular to the quay, with exchange areas at the block ends. This is often called an ‘end-loading’ operation. A popular endloading design uses two identical ARMG cranes in each container block, running on the same rail with the main operating areas (see Figure 1).
After the ECT Delta Terminal successfully pioneered the first ARMG yard, automated RMG operating models where taken into use at Thamesport in the UK, at Container Terminal Altenwerder in Germany, at Ohi Terminal in Japan, and at Evergreen in Taiwan. The ARMG operating model and technology were field-proven. An alternative ARMG operating concept was also developed, in which the exchange areas were moved from the block-ends to the block sides, along the full length of the block. Because the cranes need to reach over the truck lanes, larger rail-mounted gantry cranes with cantilevers (CARMG) are used for such ‘side-loading’ blocks. CARMG blocks are built parallel to the quay. This provides a typical CARMG container block layout (see Figure 2), which has been selected in locations with higher transshipment cargo flows.
RTG operating model gains ground
The ARMG and CARMG operating models have gained ground, but not at the expense of the rubber-tyred gantry (RTG) operating model, which has grown as well. The RTG operating model can offer important advantages for greenfield terminals, brownfield terminals and terminals undergoing conversion. The RTG operating model is suitable for container terminals with land use restricted by the surrounding environment e.g. ports located in densely-built urban areas. The RTG
operating model is especially suitable for terminals, now using reach stackers or straddle carriers, which want to move to a higher-density stacking operation for higher productivity.
The RTG operating model is very adaptable and flexible. It can also achieve a container stacking density approaching that of its ‘stiffer big brothers’, the ARMG and CARMG. See Figure 3 for a typical RTG container block.
When a truck ‘by-pass’ lane is added between the container blocks, the RTG operating model offers good truck access to the exchange area – practically as good as the CARMG operating model.
Automated RTG model: solving the process problems
Despite the strong evolution of container yard automation globally, there has been only one implementation of unmanned RTG cranes. This was at TCB Japan, where unmanned RTG operation was achieved in 2008.
Why has automated RTG operation not gained more commercial ground? Theoretically, building an automated RTG (ARTG) operation should not be that different from building an ARMG operation. In practice, however, an automation model based on rubber tyres is very different from an automation model based on rails.
Let’s look more closely at the processes involved in building an ARTG operating model. Let’s start with a typical manned RTG container block (see Figure 3). When this is converted directly with the same layout, the ARTG block would look like Figure 4.
When we compare the ARTG block layout with the field-proven ARMG and CARMG block layouts, the main difference in the ARTG layout is how the exchange area is integrated in the area of ARTG operation. In ARMG and CARMG blocks, the manned vehicles are kept separate from the automated cranes in the exchange areas. The separation is typically achieved using fences and truck driver booths. In manned RTG operations, 80 percent of the accidents in the RTG yard area are related to running over personnel.i A safety-first approach is vital for the ARTG operating model.