The boom of a barge mounted ringer crane working on the Bay Bridge in San Francisco bay, collapsed yesterday.
The crane, a long serving Manitowoc ringer, was lifting temporary supports out from under the deck of newly anchored span of the suspension bridge, and was lowering a 117 tonne section onto another barge when the boom twisted sideways breaking its heel pin/pivot point free from the outer – ringer- slew ring. The crane was reportedly rigged with 51 metres of boom and was set up with a standard backmast.
As far as we are aware there were no injuries and no one hurt in the incident.
There are several possible causes for such failures, the most common being excessive side loadings. This is particularly true for regular cranes mounted on barges where side loadings can be a fact of life.