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Large structures such as the ill-fated roof panel at Miller Park should not be lifted by crane in winds of 20 to 32 mph, according to two veteran crane accident investigators.
"It would set off alarm bells in my mind," said Ronald Kohner, an engineer at Landmark Engineering Services Ltd., Roseville, Minn. "Somebody's got a decision they're going to have to account for, in my estimation. Wind is always a major consideration in a heavy material lift." "I can't say categorically that they always will be dangerous, but in a general sense, for land-based construction, that level of wind would be excessive," said Lawrence Shapiro, an engineer at Howard I. Shapiro & Associates, Valley Stream, N.Y. "If it had a Valley Stream, N.Y. "If it had a large surface area and 25 to 30 mph winds, yes, that could be a problem. An analogy would be flying into Martha's Vineyard at night. Is it done? Yeah. But is it a good idea? No."
Wind gusts up to 32 mph were recorded in the Milwaukee area July 14, when a crane was hoisting the 400-ton panel of roof for Miller Park. Witnesses at the accident scene said the crane, known as "Big Blue," collapsed, sending the roof section crashing to the stadium below and killing three ironworkers at the site.
INHERENT DANGERS
As an indication of the inherent dangers of such winds, the New York City building code forbids cranes from operating in winds greater than 30 mph, Shapiro said.
"I mean, a 30-mph wind disturbs you when you're walking along down the street," Kohner said. "You're like, 'Holy -, it's windy."'
Kohner, a commissioner of the National Commission for the Certification of Crane Operators, has investigated hundreds of crane accidents throughout the world in his 28 years as an engineer. He also is a safety consultant who is hired to prevent accidents at large construction sites.
Kohner said one of the contractors involved in the Miller Park project asked him one day after the accident to investigate the Miller...