The reconfiguration of the existing antenna spire at the top of the Empire State Building improved service for various broadcast FM radio stations in the building that reach more than 16.4 million radio listeners throughout the tristate area.

To complete this project without impacting the Empire State Building’s daily tourist and tenant activity and without having to erect scaffolding, the team developed a “cocoon” on a 560-sq-ft aluminum elevated work platform that hid workers from direct view from the sidewalk 1,250 ft below and provided protection between construction and the open-air observatory.

Workers transported 22 tons of reinforcing steel through the cocoon’s narrow passageways. All materials had to be transported between 2:00 a.m. and 8:00 a.m., when the building’s observation deck is closed to the public. The project also involved the addition of 39 tons of structural steel to support future upgrades to the building’s broadcast equipment. 

Because the building is a landmark structure, the aesthetic challenge was to minimize changes in appearance. Project planning took two years, including six months for design of the cocoon.

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