Cargo Chat is a discussion forum on cargo handling, safety and health, and related issues. It is prepared for Forkliftaction.com News by ICHCA International, a representative organisation of international cargo-handling interests. The column is based on ICHCA's bimonthly e-newsletter and its International Safety Panel activities.

This month's forum considers a topic discussed by ICHCA International's International Safety Panel.

Container cranes

A recent tragic incident in which a manoeuvring ship struck a quayside container crane and caused it to collapse, killing one person, has highlighted the crane's vulnerability. One feature of large quayside ship-to-shore cranes is that, to maximise their outreach, most are positioned so the front legs are very close to the quay edge. With container ships getting larger all the time, including the width of decks and hold container stows, container cranes have had to increase in outreach and capacity. That has led to larger, taller, heavier structures. It was once the norm for such cranes to have a capacity below the spreader of 30 tonnes, but it is now common for that value to be more than 70 tonnes and the overall weight approaching 2,000 tonnes.

Ship-to-shore cranes are sturdy, strong and disaster resistant. However, in two respects, they have vulnerabilities. Despite their size and weight, they can be moved by high winds. With the cranes' braking systems being on the motors, if a crane starts to move it is very difficult to stop it. Special equipment and systems have been added to anchor them when high winds are expected and stop them if they start to move.

The incident highlighted the other vulnerability. The cranes are very strong, lifting containers vertically out of ships, which means having an extensive boomed outreach, and bringing them back over the quayside and depositing them on the ground (and the reverse). But the cranes' tall legs are vulnerable to sideways impact from ships' superstructures or hulls. A moving ship, even if it is moving slowly, has considerable momentum and force and the flare of the ship's bow or parts of its superstructure can overhang. That means that, during berthing or sailing, it is possible for the bow or superstructure to touch, strike or otherwise impact a front leg. Such contact often means the crane collapses and it is common at container terminals to park cranes out of the way of ships' normal approach/departure paths.

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