ABB, formerly ASEA, has been active in supplying cranes and equipment for over a 100 years and to this day has supplied electrical and automation equipment to more than 1,200 cranes of all types and in all parts of the world.
ABB has and will supply automation and electrical scope to a number of demanding automation projects including:
• Le Havre (SETO, 2003) – five double trolley STS
• Kaoshiung (Evergreen, 2005) – six cantilever RMGs
• Euromax (Rotterdam, 2005) – order for 16 STS and 58automatic RMGs
• TPCT (Taipei, 2007) – order for 40 cantilever RMGs
• Hanjin (Busan, 2007) – order for 42 cantilever RMGs
• PNC (Busan, 2007) – order for 31 cantilever RMGs
Our focus is to use proven but at the same time state-of-the art technology in order to facilitate a safe, cost effective and highly productive handling of containers for terminal operators.
Several automatic concepts have been introduced and are presently employed around the world. In the following, a comparison will be made between two handling concepts that can be employed when the available yard area is limited and high stacking needs to be introduced. Another parameter that is becoming more and more important is the reduction of emissions from diesel engines.
The automatic cantilever RMG (Cantilever Rail Mounted Gantry, CRMG)
Container transfer in and out from the stack is made alongside each other. The area in which automatic operation takes place is fenced in, while controlled access to this area is made via card operated gates.
All movements within the yard area and above a certain height over the travel lanes are performed fully automatically. RFID readers can be located at the lane entrance in order to check truck/chassis identity.
When loading/unloading manned vehicles the last part of the operation is conducted under the supervision of operators which are located in a remote office. An operator can handle four to six cranes.
Cantilever RMGs can be made with very large spans and stacking heights and can be moved along the rails over several stacks but cannot be moved from one row of stacks to the next. The crane length is larger than that of an RTG because the containers have to be lifted between its legs.
The RTG (Rubber Tire Gantry)
This is one of the most commonly used vehicles for yard stacking
and needs no further introduction. Each vehicle is manned with a
driver; house-keeping is limited since the ability to move a loaded
container in gantry direction is limited.
The RTG can be moved between different stacks in the
terminal. Modern RTGs are equipped with positioning systems,
(e.g. auto-steering, DGPS and cameras are being introduced in some places in order to improve the driver’s overview).
The CRMG can replace the RTG in almost any terminal and a comparison between the concepts can be made (see Table 1).
When comparing the two alternatives the following factors are the most important:
• Crane prices
• Labour costs
• Operational differences
Current prices for a typical RTG are well above one million US dollars (dimensions: 1 + 6 wide and 5 height). For automatic CRMGs, more than 100 have been ordered during the last year and a standard price basis established. The conclusion is that price difference between the two alternatives can be assumed to range between 0.5 – US$1 M/crane. Labour costs vary from US$10,000 – US$100,000/man-year and includes social cost, administration and labour planning etc.
The RTG flexibility is compensated by the fact that the CRMG can perform automatic house-keeping, has a shorter cycle time and can reposition itself quicker due to a higher gantry speed. Furthermore, with the introduction of modern TOS-systems, containers can be more evenly distributed over the yard so that the cranes are not required to move between rows of stacks. For the CRMG alternative, an additional TOS-investment of US$2 M has been taken into account. This investment depends upon the size of the port. A cost capital of six per cent has been assumed.
In order to compare yard operations using the two alternatives, a simulation has been performed in cooperation with TBA, Netherlands.
A model port with the following data was used:
• 600,000 boxes/y
• Six QCs with a WS peak of 180 moves/h
• ITVs between quay and CRMG on the WS, external trucks serviced on the LS
• Dwell time five days
• Empties handled by FLTs
These assumptions allow for a real comparison between the two alternatives as the operations and all employed cranes and vehicles are similar.
Yard operations were simulated using RTGs and automatic CRMGs respectively, and simultaneous LS and WS peaks were assumed. For the RTG results, a bench-mark has been performed with an operational RTG terminal. As input to the transport cycle for the auto CRMGs, real data from performance testing real data from performance testing was utilised.