It will take months to determine the cause of the Feb. 16 accident at the 4 World Trade Center construction site in which a crane cable snapped, dropping its load of steel beams 40 stories, says the Port Authority of New York & New Jersey. No one was injured at the site as the beams plummeted and hit the flatbed truck used to transport the load, says the agency, which is overseeing the investigation.

Work has resumed at the site after part of it was shut down temporarily pending an investigation, the Port Authority says. “The crane in question is permanently out of service” and has been replaced by other tower cranes, the agency said in a statement. It adds that the accident did not affect work on the other projects at the site.

“The investigation will take months given the reviews that will be done, including expert reviews of the crane's hydraulics and metallurgy,” the agency says. It adds that it has met and will continue to meet with Community Board 1, which consists of local community representatives, for updates on the progress of the investigation.

The ongoing investigation includes officials from the crane owner and operating company, the Occupational Safety & Health Administration, New York City Dept. of Buildings’ Cranes & Derricks Division, New York State Dept. of Labor and the developer Silverstein Properties.

The 4 WTC tower, located on the southeast corner of the WTC site bounded by Greenwich, Church, Cortlandt and Liberty streets, is set to rise 977 ft above street level when it is completed in 2013.