07.06.2007

Harbour cranes should double cycle

A study in the USA has concluded that harbour cranes could be used more efficiently if they unloaded and loaded ships simultaneously.

Assistant Professor Anne Goodchild of the University of Washington and Professor Carlos Daganzo of the University of California-Berkeley have shown that double cycling of cranes would also save costs and conserve fuel.

Typically, a harbour crane unloads all the containers from a ship - dropping the container on the dock and then swinging back empty to pick up another load. Once the ship is empty it then starts to load outgoing containers onto the ship.

Double cycling seeks to maximize crane operation by unloading one container and then immediately picking up a new container on the dock to load onto the ship.
The technique is already in use at a few terminals but has not been widely adopted due to fears that it would complicate port operations.

"When terminals do use double cycling they only do it below deck, and then only within one bay," Goodchild said. "I would suggest that be implemented much more broadly."