12.05.2007

Flawed design caused crane collapse

Washington state’s department of Labour and Industry (L&I) has issued its report on the catastrophic tower crane accident in Bellevue, Seattle last November.

The report says that the cause was clearly related to the inadequate design of the I-Beam base which had, it says, less than 30 percent of the required structural strength.
See Foundation blamed
The 70 metre crane was mounted on an H shaped I-beam frame supported by four concrete pillars rather than the traditional poured concrete foundation.

Investigators said that excessive winds and operator error were not a factor in the accident. The report says that the crane operator was well experienced and that he had operated the crane properly.

"The inadequate design of the tower-crane base clearly led to the collapse of the structure," Steve Cant, assistant director for the agency's Division of Occupational Health and Safety. The problem was compounded by the failure of the general contractor to maintain and inspect the crane base in accordance with the manufacturer's specifications."

The L&I findings concluded that the eventual cause of the collapse was "metal fatigue of the steel base frame, which was not strong enough to support the working crane."

Two companies are being cited for workplace safety violations: Magnusson Klemencic Associates, the engineering firm that designed the base, and the general contractor Lease Crutcher Lewis. L&I has proposed a fine of $5,600 for Magnusson Klemencic and a total of $9,200 in fines for Lease Crutcher Lewis. The companies have 15 working days to appeal the citations.

Lease Crutcher Lewis was fined for not ensuring the crane was maintained and used properly, not inspecting the tower and for hanging two large banners on it that could affect the crane's operations.

L&I described the fines as involving "serious violations," but did not determine whether negligence took place.

According to L&I spokeswoman Elaine Fischer the penalty amounts are based on a structure set by law. If L&I had found the same violations and the crane hadn't fallen, the penalty amounts would have been the same.

Jon Magnusson, chairman and CEO of Magnusson Klemencic said that his firm would appeal immediately. "The Department of Labor and Industries made several factual errors in its investigation which they refused to discuss despite MKA's repeated attempts to do so,"

Bill Lewis, president of Lease Crutcher Lewis, said he wanted to study the reports findings before commenting.

“We're not surprised that they're going to appeal, it is common for businesses to appeal L&I's findings”, said Fischer. The penalties are proposals that do not become final until the appeal process is over.

The Washington state legislature has approved new regulations for construction cranes, including a provision that plans for nonstandard tower crane bases to be reviewed and approved by an independent professional engineer.

Investigators said they didn't know why the crane mounting base was engineered as it was, but speculated that it may have been done for reasons of time and money.

The falling crane killed a Microsoft lawyer, Matthew Ammon, a tenant in one of the buildings.

Ammon's mother, Kathleen Gaberson, said in a statement issued by her lawyer. "There is little comfort in knowing what caused the tragedy that killed our only child. The report shows that his death could easily have been prevented. This needless tragedy has devastated our family."

Vertikal Comment

The speed with which this investigation and report have been completed is admirable, the UK’s HSE should take note. In comparison the Canary Wharf report, back in the news this week, took four years to issue.

The report, conclusions and any possible legal action against those involved in the fatal tower crane accident at Durrington High School, Worthing, over two and quarter years ago, has still not been completed.

The causes of a crane accident can often be established within the first six to ten weeks. Dragging an investigation on for years rarely makes it more accurate. In the meantime some lessons that might be learnt from the accident are not and a possibly innocent company suffers from having the uncertainty of legal action hanging over it.

The UK has laws against extraditing criminals to the USA if the defendant might be subject to the death penalty. Not because of an objection to the death penalty itself, but due to the way the death penalty, left hanging over those found guilty for years, being Inhumane and excessively cruel.

And yet the HSE has been guilty of committing this offence with companies involved in some fatal crane accidents.

Can we not take a leaf out of Washington’s book?