This skyscraper will be located atop a subway line and built entirely around an existing building.

Skyscraper Pays Homage to Cast Iron District

The building comprises a 41-story tower and 9-story podium. The tower will need to built entirely around—and above—an existing Metropolitan Transit Authority mechanical and ventilation building. ©Related-Oxford

The Manhattan tower—which will be located atop a subway line and enclose an existing transit mechanical and ventilation building—will honor the Cast Iron Historic District located nearby.

July 1, 2014—The design of the 780 ft tall office tower that will be built at 55 Hudson Yards in Manhattan has been released. The skyscraper will join the 28-acre development that is currently being built almost entirely atop a functioning rail yard. As such, space is at a premium. Although the tower will be located adjacent to the rail yard platform, it will still need to built entirely around—and above—an existing Metropolitan Transit Authority mechanical and ventilation building, with a basement that will float above escalators for the No. 7 subway line, which crosses beneath the site.

The 1.3 million sq ft office building, which will be located at the intersection of the High Line and Hudson Park and Boulevard, will stand 51 stories high. The building consists of a 41-story tower atop a 9-story square podium, each side of which will contain 3 to 4 miniterraces at various levels. A rooftop terrace with trees and greenery will be located atop the podium.

The building’s exterior has been designed to pay homage to the classic SoHo cast-iron architecture that dates back to the mid-19th century and which is located near Hudson Yards. (The SoHo Cast Iron Historic District was designated as a National Historic Landmark in 1978.)

“In our design, we sought to tie the aesthetic of the Hudson Yards district back to the industrial character of the meatpacking district and Chelsea,” said A. Eugene Kohn, FAIA, RIBA, JIA, the chairman of KPF, who wrote in response to written questions posed by Civil Engineering online. “We saw our design as a rethinking of the textured buildings of New York,” he said.

With its cast aluminum and glass façade, the 780 ft tall office tower that will be built at 55 Hudson Yards in Manhattan pays homage to the SoHo Cast Iron Historic District.  ©Related-Oxford

The New York office of international architecture firm Kohn Pedersen Fox (KPF) were the design architects for the building. The design was created as a joint venture between A. Eugene Kohn and Pritzker Prize-winning architect Kevin Roche. At KPF, Trent Tesch, AIA, a principal, was the design principal for the project; Anthony Mosellie, AIA, a principal, was the managing principal; and Lauren Schmidt, AIA, LEED AP, a senior associate principal, was the project manager. 

“One thing we wanted to avoid was creating a set of buildings [at Hudson Yards] that are all entirely glass-on-glass,” Kohn noted. “This can be a problem on other sites, and we wanted a break from that, and to create more of a collage in this district.” Kohn said that he and the design team chose “to embrace the history of New York’s Cast Iron District, bringing that aesthetic into a high-rise tower.” This is particularly evident in the detailing of the cast aluminum podium façade, he noted.

Because the other buildings that are being constructed atop the development’s eastern rail yard platform are sculptural glass towers, the 55 Hudson Yards design team wanted to create a simpler, orthogonal tower. “The two other KPF-designed towers—10 Hudson Yards and 30 Hudson Yards—gesture toward each other like dancers,” Kohn said. “If this building, too, were very sculptural, the site could appear chaotic, [so] we thought that the rectilinear, more Miesian approach would set this building apart and allow it to anchor the rest of the site.”

The detailing of the façade of 55 Hudson Yards, which will contain large glass panels encased in cast aluminum frames with rounded corners and layered edges, offer viewers multiple experiences of the building depending on their vantage points. “55 Hudson Yards is intended to be a simple building, but the detailing is a beautiful, soft expression—particularly the softness of the corners of the fenestration, a rich detail on a straightforward building,” Kohn noted.

The building’s superstructure will be a cast-in-place lightweight concrete structural system, according to Jeffrey Smilow, P.E., F.ASCE, an executive vice president and the USA director of WSP Building Structures, who wrote in response to written questions posed by Civil Engineering online. “The gravity framing is posttensioned flat slab utilizing lightweight concrete, supported upon cast-in-place concrete columns interconnected with concrete spandrel beams forming a perimeter moment frame,” Smilow explained. “[While] the lateral system is composed of concrete shear walls within and around the core area, extending from the foundation level through the top of the building.”

The glass modules of the building’s façade are square in the podium and become rectangular for the tower. Each side of the tower’s podium will contain 3 to 4 miniterraces located at various levels.©Related-Oxford

Approximately 50 percent of the tower will be located atop the MTA building currently located on the site, according to Smilow. “The choice of material was based upon economic and practical considerations related to load limitations imposed by the MTA structure,” he said. The structural engineers “studied a large variety of structural options, such as steel-framed, hybrid steel and cast-in-place concrete, fully cast-in-place, post-tensioned normal weight, and post-tensioned lightweight concrete,” he said. “Posttensioned lightweight concrete slabs were found to be the most economical and practical relative to the impact upon the MTA structure.” 

The engineers coordinated a post-tensioned system that also allowed for future slab penetrations, according to Smilow. This has the added benefit of allowing for flexibility for the building’s future tenants.

Although the building is not located atop either of the rail yard platforms that are being built for the Hudson Yards development, the foundations for the building still must navigate significant existing infrastructure. “Our building had to rest on caissons provided by the MTA along with the number 7 [subway] extension, so it had to lock into their structure—this is a highly unusual condition,” Kohn said. “For this reason, the building doesn’t really have a basement—the basement has to float over the escalator tunnels connecting from the station at ground level to the subway tracks.”

The structural engineers worked closely with MTA to resolve the difficulties created by the highly congested site. “Through an early coordination process with the MTA, we coordinated strategically located caissons for the support of our new concrete core,” Smilow explained. “The new caissons are located in between existing escalators leading into the subway main entrance area.” 

In addition to carrying all the loads to the caissons, the structural engineers also had to manage load paths through the MTA building itself. “The goal was to maximize the number of floors [in the tower] and limit the loading upon the MTA building,” Smilow said. In addition to the lightweight concrete system selected, the engineers also “achieved the goal by introducing an innovative tailored sequenced construction technique which routes the building’s loads to the MTA columns, which can handle high loads, and bypasses the weaker columns.”

“This new office tower is the first high rise commercial tower in New York City to use long-span, flat-slab, post-tensioned concrete floor framing,” Smilow said. “This is unique and highly economical as compared to structural steel floor framing which has been the standard for many years.” The system enables a floor-to-floor height reduction of at least 6 to 9 in. per floor, according to Smilow. In addition to decreasing the weight of the building, this “results in reduced height and significant savings in curtain wall costs,” he said.

Construction of the tower is expected to begin January 2015 and the tower should be complete by the end of 2017.

A rooftop terrace with trees and greenery will be located atop the podium, offering views of New York City and the 28-acre Hudson Yards development.