Three Supertall Slender Towers in Midtown Manhattan

Abstract

One Manhattan West (1MW), Two Manhattan West (2MW) and 35 Hudson Yards (35HY) are three slender supertall towers recently designed and engineered by the authors' company that rise above the underground train tracks approaching New York City’s Penn Station on the west side of the island of Manhattan. Although the slender towers are neighbors and have similar heights and proportions, each tower resolves the constraints of the underlying tracks with unique structural approaches. The disparate below-ground conditions result in three distinct structural solutions that are all governed by the effects of the wind. All three towers were subjected to extensive wind tunnel testing programs in order to optimize their dynamic behavior. The structural system of 1MW is a reinforced concrete core and a perimeter steel moment frame. The site conditions prevent the perimeter of the 304-meter-tall tower from reaching the foundation. This challenge is addressed by sloping the perimeter columns to the core above the ground, thus making 1MW one of the slenderest structures in New York City. The structural system of 2MW consists of a central braced steel core with outrigger and belt trusses and a perimeter steel moment frame. Half of the core is undercut by train tracks; loads are strategically moved to the perimeter structure, which is tightly integrated with tracks below. 35HY is an all-concrete mixed-use tower where one of the main challenges was to align core wall and column placement with the spacing of the existing tracks below while trains continued to be operational.