Friday, July 11, 2008
How unsafe are topless tower cranes?
Yesterday July 10 a tower crane collapsed in Rotterdam on top of the building it was working. The operator was killed. The crane was a topless tower crane. It broke off just under the operator cabin. It was the same type of crane as the two New York accidents earlier this year, March 30 and May 15. In one case a collar broke as the crane was being jacked, in the other case the lifting arm broke off, in the same place it had broken an been welded before. Here is an analysis from a similar tower crane accident in San Francisco. Here is one (two) in London, mentioning another in Battersea reporting the arm of the crane including the cabin coming off the tower.
I can't help but wonder: How safe are topless tower cranes? Even though I read they are supposed to be safer than other types of cranes including the tower cranes with top, I did a little search on the internet and it seems that when the other cranes collapse in most cases there is an obvious human error in play, like very large load combined with a large lifting radius. In many cases "human error" is an understatement and the operators amply qualify to be nominated for a Dodo award. I'm not even mentioning the accidents when a crane is lifting something out of the water. (That happened to us once, we didn't realize that the vacuum force of the water pulling on the bottom surface of the object was multiplying the weight with a factor... big mistake, the crane went in and we needed a second crane to lift the first one out. See, that's why I am not mentioning..) On the other hand tower cranes seem to want to collapse when the operator has a cramp in his little finger, still the cause is always reported as human error.
The workers on the Rotterdam site report that this could not have been the drivers fault. Before the crane broke the operator succeeded to bring the load back closer towards the crane tower thus saving the lives of others who were working in the vicinity underneath. This was not a reckless crane operation on a site with insufficient supervision. No blame can be put on the workers, the fault will have to be sought higher up this time. A good man died, let's take this problem serious. How unsafe are topless tower cranes and can they be made safer?