Tower Crane Topples
Falling machine crushes town house, kills seven
 A building on 50th Street damaged by the falling crane. Aaron Seward |
According to reports, the crane toppled after workers jumped, or raised the crane and were installing a structural steel collar to attach the mast to the concrete structure. During the installation procedure, the collar fell, smashing into another collar that attached the mast to the 9th floor and disconnecting it. Both collars then fell to the base of the tower and the destabilized crane tipped over.
 The crane fell from this development at 305 East 51st Street. Aaron Seward |
According to the source, another factor that may have attributed to the fall was the crane’s floating foundation. Tower cranes are designed to be freestanding up to, and sometimes above, 200 feet; but they have to have solid concrete foundations in order to absorb lateral loads, which this crane did not have. Most developers are loath to spend a quarter of a million dollars on a temporary foundation for a crane, and so engineers have to rely on tiebacks to the building, which leaves no redundancy if the tiebacks fail.
The real trouble with the situation is that while the workers involved in the accident were doing things by the book, the book itself has two loopholes that may have led to the catastrophe: The city allows people who are not professional riggers to execute crane jumps, and does not require stand-alone foundations for tower cranes.
The city will most likely tighten regulations on crane jumps as a result of this accident by requiring that a master rigger and professional engineer be on site during jumps, and perhaps requiring more robust foundations. The regulations were tightened last year after sections of a tower crane fell on a taxi on 3rd Avenue during a jump, that time by requiring that a licensed tower crane rigger be on site during the process. Previously, tower crane riggers only had to be onsite when a crane was put up or taken down.
In spite of these regulatory shortcomings, New York City’s crane laws are the most stringent in the nation, even more restrictive than those required by federal Occupational Safety and Health Administration regulations. “If you compare the number of cranes in the city with the number of injuries it’s a pretty low percentage,” said the source. “You look in the newspaper in Florida and every day you see cranes tipping over. We don’t have that. But because of our environment, when something goes wrong it goes catastrophically wrong and takes out a building.”
The DOB’s investigation is looking into the companies involved with the construction site, including Joy Contracting, a New Jersey-based concrete company that held the crane contract and employed the operating engineers involved. The DOB is also investigating Kennelly Development Company of Manhattan, the developer of the property, a residential condominium, and the general contractor, Reliance Construction Group (RCG). Both Kennelly and RCG expressed their sympathy to the victims and said that they are cooperating with government agencies in the investigation.
AARON SEWARD
