Comments about technological history, system fractures, and human resilience from James R. Chiles, the author of Inviting Disaster: Lessons from the Edge of Technology (HarperBusiness 2001; paperback 2002) and The God Machine: From Boomerangs to Black Hawks, the Story of the Helicopter (Random House, 2007, paperback 2008)

Saturday, February 6, 2016

Another Large Crane Mishap, NYC

About the fatal crane accident in lower Manhattan yesterday, which happened while the operator was lowering the crane boom and jib to reduce toppling risks from a rising wind ...  From the sparse photos, this unit looks like a Liebherr LR1300, which wouldn't be counted as a supercrane. The crane was rigged for a long reach and light pick.

It was carrying a lot of mast and jib, 565 feet of it according to reports, but it must have handled such a dead load before, since crews had put the sections together on the ground, after which the operator raised it to position. 

Given that the car body flipped over on its back, I'd guess that the luffing cables didn't snap; that is, the falling mast and jib dragged the car body over on its back, with the rising counterweights providing the momentum. 

Some things the NYC investigators will look at: was there extra weight on the hook, mast, or jib that would have overbalanced it; did the pavement collapse under the front of the tracks? I assume that the crane had been sitting on timber mats, but I can't tell from the photos, which show the crane after it overturned. Mats are important to keeping big cranes upright. 

Kudos to news reporters that call this a tip-over rather than a collapse. When a structure falls intact, as this crane apparently did, I wouldn't call that a collapse. 

Second note to reporters: nearly all the photos posted are of the mast and jib in the lay-down zone. Yes, these tell us the tragic damage such a machine can cause, but it doesn't convey much information compared to a close look at the car body, undercarriage, counterweights, crane mats, and hoist rigging. 

Terminology for big crawler cranes like this is available in my post about the crane tip-over near the Grand Mosque at Makkah.

Also, here's a reposting of my item "How to Park Your Super-Crane," fixing a broken photo link.  

No comments:

Post a Comment