06.12.2006

Third crane shut down in Bellevue

A third crane was taken out of service in Bellevue Seattle after contractor Skanska contacted the crane owner to carry out a detailed inspection following the state advisory to check for cracks after a crane was discovered with large cracks in its structure last week..

Morrow carried out a detailed inspection using a suspended platform and found a fine hairline crack on the outside of a section. It ordered the crane to be taken out of service while it carried out repairs.

There were 13 cranes in Bellevue when the fatal collapse occurred on November 16th, a second crane was dismantled over the weekend after large cracks were found in some of its vertical tubes. Leaving 11 one of which is the one above.

State officials are now saying that the large cracks in the dismantled crane were most likely caused by blocked drain holes in the vertical tubes, which allowed a column of water to build up inside the tube, not difficult given that the Seattle area is one of the wettest in North America.

A particularly wet period was followed by a rare spell of freezing weather which, it is said caused the retained water to expand and crack the steel tubes.

The contractor involved on that site, Hanover construction, is strongly disputing the blocked drain hole theory and says that it does not know yet what caused the cracks.

The latest crane has a height of 60 metres and as with the other two cranes is a Liebherr and was erected by the same company, Northwest Tower Crane Service, based in Tukwila.

Vertikal Comment

We are in danger of tower crane paranoia breaking out, residents in parts of the Seattle area and London now live in fear of tower cranes. They are no longer ignored as part of the downtown scenery, but are increasingly seen as sinister killers. Rather like see a group of birds after watching Hitchcock’s classic film.

On Friday when the first crane in Bellevue was discovered with cracks several local residents fled to hotels which the contractor agreed to pay for.

In London a group of residents have formed an action group to seek changes to where tower cranes are erected and how they are policed.

In East Sussex a Falcon tower crane set up near a school generated complaints due to a broken side window which, they say, made it look old and dilapidated- unsafe. The crane was dismantled and a reassembled with additional features and operating time restrictions are to be clearly posted for all to see.

So what is happening? Is this just a phase that we are passing through heightened by an increased population of tower cranes brought on by the buoyant construction market? Or do we really need to step up the diligence applied to tower crane inspections?

Whatever it is, tower crane companies and crane associations everywhere ought to be seen to be tightening up their game and to make it be known that this is happening, if not there is a real danger that the regulatory authorities will step in and do it and that rarely works out for the best.