LOWER MANHATTAN — The city is ordering contractors to lighten the weight carried by cranes across the five boroughs in the wake of a frightening accident at the World Trade Center last month, a contractor said.
Until investigators figure out why the TG-1900 tower crane at 4 World Trade Center suddenly dropped a massive load of steel beams from 40 stories high on Feb. 16, the Department of Buildings is asking all contractors with similar cranes to use only up to 75 percent of their capacity, Tishman Construction Corp. revealed Monday.
"All their loads have been reduced while they're under investigation," Bethany Klein, vice president of structural engineering at Tishman, which is building at 4 World Trade Center, told Community Board 1 at a meeting Monday night.
Klein said the DOB recently sent a letter to Tishman informing them of the new rule — and added that the letter said contractors citywide who operate TG-1900 tower cranes are subject to the new regulation. The Department of Buildings did not immediately confirm the policy and did not respond to multiple requests for comment.
The enormous cranes, used to build skyscrapers, normally have a capacity of up to 150 tons, according to one company that rents them.
Tishman executives attended Monday night's meeting to assure residents of 4 World Trade Center's safety following the construction accident, in which three steel beams plummeted to the ground but amazingly did not injure anyone.
Dwayne Carter, vice president of corporate safety for Tishman, said the reason no one was hurt is that all workers were following safety rules and kept their distance from the crane as it lifted the steel.
"If we didn't put into place [these] protocols…it would have been a total tragedy — it would have," Carter said.
However, the executives declined to say which part of the tower crane had failed. The crane was manufactured in 1976, but some of its pieces were newer than that, Klein said.
The Department of Buildings, the Port Authority and the Occupational Safety and Health Administration (OSHA) are all investigating the accident, Tishman representatives said.
"The investigation will take months given the reviews that will be done, including expert reviews of the crane’s hydraulics and metallurgy," a Port Authority spokesman said in an emailed statement after the meeting.
An OSHA representative declined to comment because the investigation is ongoing.
Tishman removed the TG-1900 tower crane from the north side of 4 World Trade Center almost immediately following the accident and continued construction using the other crane, which is a different type, on the building's south side.
The contractor continues to use a TG-1900 for construction of Tower 3.
The accident set work on the tower back about two months, so it will now top out in early July rather than in early May, Tishman officials said.
The building is scheduled to open at the end of 2013 or the beginning of 2014.