A partially collapsed construction crane dangling ominously from the top of a unfinished New York City skyscraper is "stable," but the site's construction company and a crane expert worry that its heavy boom could smash to the street below.
Mayor Michael Bloomberg said today that "the Department of Buildings has determined that the crane is currently stable," but winds remaining from superstorm Sandy remained too high at the top of the 90-story luxury high rise building for crews to work on it.
"The procedure there when the winds die down will be to get the boom and strap it to the building," he said, adding that "the contracting company will have to figure out ways to build a new crane on top and take that one down."
The contracting company is Lend Lease Construction, which manages the One57 construction site, a $1.5 billion luxury residential tower being built near Central Park at 57th Street. One57 is owned by Extell Development Co.
"We are working with structural engineers and the DOB [Department of Buildings] on evaluating any additional measures that can be taken to secure the boom and crane structure. Current weather and wind conditions remain very severe," a Lend Lease statement said today.
The boom is hanging over West 57th Street, normally one of the busiest in the city, and despite Bloomberg's assurances that the boom is stable, others are concerned.
Lend Lease senior vice president Mary Costello said in a statement, "NYC emergency personnel remain on site and have cleared all bystanders from the potential impact area should any additional failure take place."
Terry McGettigan, active tower crane operator in Seattle with 36 years of experience in operating, inspecting and repairing tower cranes, said he has been watching the incident unfold from the West Coast.
"It's not hanging on by much now and it keeps bending back and forth," McGettigan said. "It could finally come down."
"I don't think the whole crane will go down, but I was surprised the boom stayed on," he said. "I thought for sure when I woke up this morning that it would be on the ground...because of the way it was flopping around in the wind, you know. They got lucky."
McGettigan said depending on the model, this tower crane can weigh over 50 tons.
Costello said the crane, which is owned and operated by Pinnacle Industries, became damaged by the high winds of superstorm Sandy, adding that "the hurricane storm winds have pushed the crane boom over the cab section of the high rise crane."
The crane was last inspected a few days ahead of Sandy smashing into the city. "The crane was last inspected on Friday Oct. 26 by the Operating Engineer from Postroad Ironworks following a checklist provided by the Engineer of Record," Costello's statement said.
Attempts to reach a representative at Pinnacle Industries or Extell were not successful.
McGettigan estimated there are about 15 to 20 tower crane collapses worldwide every year said there are a number of factors that could have contributed to the crane collapse in Manhattan.
He said tower cranes are designed to withstand a maximum of 100 mph wind speeds if they are properly "weathervaned," which means releasing the swing break so the crane boom can move with the wind. This can be done manually or by the push of a button, and is a standard protocol for operators who are leaving cranes unattended overnight.
But the higher up the crane, the less wind speed it needs to topple, he said.