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, operated by contractor American Bridge/Fluor, 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 in a tandem lift with a similar crane on a jack up barge.
The two cranes were hooked onto a cradle to carry the support components as they were cut free from the underside of the bridge. In this case the component apparently slipped out of or moved in the cradle, causing the boom of the damaged crane to twist sideways breaking its heel pin/pivot point free from the outer – ring- 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.