Innovation in Managing High Risk Construction
Concrete Core Grows above the Steel
Plaza Construction LLC Brings a First to New York City
Typically, high-rise construction in New York City calls for the steel frame to be erected before the concrete core is set in place. Built by Plaza Construction LLC for SJP Properties, 11 Times Square is different. In this case, the steel frame rose behind the concrete core which stiffened the structure and saved the developer time while enhancing quality.
“No other commercial building in New York City is being built this way,” says Plaza Construction President Richard Wood. “We have proven that we can build a commercial high-rise building in New York City using this method.”
The method has been used in a handful of locations across the country, and with the success of the method at 11 Times Square, it is sure to become more common in New York City.
Wood, along with the climb-form manufacturer and Sorbara Construction, the concrete subcontractor, devised a combination approach of fall protection and debris retention to insure the safety of the ironworkers. As the system went up, it proved extraordinarily effective.
To insure the highest degree of safety, additional measures were added including cocooning the external perimeter of the Peri-form system, and creating an internal plywood based barrier system. The cocoon guarded against wind, falling debris, and aided in fall prevention.
The pace of the steel erection was consistent with the concrete erection, so the gap between the climbing form and the steel below stayed the same throughout the construction of the building. When the top was reached and the concrete core complete, the form system was removed and the steel was erected to envelop the concrete core.
At the top deck, where the perimeter could not be fully cocooned, a double-height barrier prevented wind blowing objects off of the form system.
Plaza also developed fire safety measures, including installing a permanent building standpipe with a temporary cross-connect so water could be provided to the top of the concrete form at all times, and egress for workers was available at any given time so that the top could be accessed by a system of stairs. Workers could also be lowered of the form if necessary.
Unprecedented Industry Collaboration
Working with the unionized New York City construction trades, Plaza Construction was able to modify means and methods to establish a higher level of confidence in the safety of the erecting of the concrete forming system prior to the steel for 11 Times Square.
The project represents an unprecedented collaboration to create innovation in construction and safety as well as significant time savings.
“We all worked hard to build confidence in this project from day one,” says Wood. “We worked closely with the Iron Workers of Local 40, continually building confidence in the reliability of the approach. All of the trades worked together and produced a model that shattered long- held perceptions that it couldn’t be done.”
The NYC Building Department’s Building Enforcement Safety Team (BEST) requires each site to have a Site Safety Manager. At 11 Times Square, Plaza Construction treated the climbing form and the steel building as separate work sites and provided a Site Safety Manager for each. The result was two Site Safety Managers on site coordinating activities of the concrete work with the steel work.
“We meet with the BEST squad weekly and it worked out very well. At Plaza Construction, it’s our goal to increase efficiencies without sacrificing quality or safety.” Wood says. “It’s also imperative that our industry continue to think innovatively about how we go about doing our business. We expect the success of 11 Times Square, in terms of safety and efficiency, will usher in a new generation of commercial construction in New York City.”
SJP’s development philosophy is summarized by Doug Allen, Executive Vice President. “By teaming with the NYC Buildings Department, the Design Team and the Construction Team, 11 Times Square brings a new standard of innovation, efficiency and uncompromised quality to the marketplace.”