With this in mind, the port authority chose RTGs rather than rail mounted gantry cranes (RMGs) because they are perceived to be more flexible and easier to move.

Sweden's Kalmar Industries won the order for four of the widest RTGs the company has ever built, 4+1 high and 9+1 wide. Two will be delivered at the end of this year and two at the beginning of 2003.

The power feeding system for the electrically powered RTG is similar to that of the RMG.

However, unlike RMGs which follow rails set in the ground, Kalmar's RTGs are steered by an automatic gantry steering system called Smartrail which is based on DGPS.

In addition to Smartrail, the new RTGs will be equipped with a Remote Crane Monitoring System (RCMS) which enables the operation of the machines to be monitored remotely, in real time, by a single operator in the terminal control room.

RCMS works by transferring information collected by the crane's PLC system to the control room via a wireless local area network.

This allows the control room staff to be aware of alarms, driver acknowledged information and operational data. Machines can also be monitored via the internet by Kalmar's customer support department, providing real time support and assistance if required directly from the factory.

Customising and modifications to machine operations can also be done via the internet since the crane PLC system is also accessible via the RMCS.

MJ Information No: 17024