How This NYC Skyscraper Is Being Built On Top of an Existing Building

As if building an entire neighborhood on top of an active rail yard were not already crazy enough, the developers for Hudson Yards are also planning a 51-story tower that will be constructed on top of and above an existing building. Yup, Manhattan is a crowded mess.

Hudson Yards is the largest private real estate development in U.S. history—an audacious plan to float 5 skyscrapers, 15 acres of public space, and 5,000 residences above a functional rail yard. As detailed in a recent article for Civil Engineering, one corner at 55 Hudson Yards actually juts past the edge of the rail yard, but that doesn't mean building here will be much easier. Designers, engineers, and workers will have to fit the tower at 55 Hudson Yards above an existing MTA mechanical and ventilation building. Its basement will hover above the 7 subway line, which passes right under 55 Hudson Yards.

How This NYC Skyscraper Is Being Built On Top of an Existing Building

Between the old building and the subway, the congested site means space for weight-bearing structures of the new foundation is limited. About half of the new skyscraper will sit on top of the MTA building, with the weight of tower partially distributed on the old building's columns. To limit the tower's weight and maximize its height, its structural engineers are planning to use post-tensioned lightweight concrete.

Construction on 55 Hudson Yards is expected to begin next January and finish in 2017. The entire Hudson Yards project should take until 2024. The old rail yard will be entirely transformed by then—both above ground and below. [Civil Engineering]

How This NYC Skyscraper Is Being Built On Top of an Existing Building

How This NYC Skyscraper Is Being Built On Top of an Existing Building

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