12:30 PM - 01:30 PM
6 October 2021

Digging Deep for a Supertall in Manhattan

Significant Projects

Bordering Grand Central Terminal to the west, this 1,400-foot-tall commercial tower encompasses an entire city block. The tower will provide $250 million in transit improvements to the neighborhood by connecting New York City Transit subways, Grand Central, and the future East Side Access Long Island Railroad terminal.

This presentation will focus on a multi-disciplinary effort to make way for a complex underground structure and a Supertall tower above. The civil engineering involved in the development included intensive topographical surveys, 3D laser scanning, relocating major mainline utilities serving the greater mid-town Manhattan area, and a deep excavation adjacent to operational subways, railroads, and other critical below-grade structures.

The primary focus will be on the civil and geotechnical design and construction challenges associated with the development including:

  • Designed a new 400-foot-long water main directly above the subway roof, which allowed for the removal of the 150-year-old cast iron water main within the site footprint.
  • Designed a replacement combined sewer to allow for demolition of the 100+ year old city sewer within the project site, and under the adjacent subway.
  • Designed excavation support systems for a 60-foot deep excavation adjacent to Grand Central, Metro North Railroad, New York City Transit subways, landmarked structures, and active city streets.
  • Designed the foundations including large footings bearing on Manhattan schist bedrock and high-capacity rock anchors to support both gravity and wind uplift loads.
  • Achieved¬†the largest recorded continuous concrete pour in Manhattan.
  • Assisted with traffic/parking design of basement-level loading docks.

Learning Objectives:

  • Describe foundation design for supertall buildings.
  • Describe deep excavation support systems and associated monitoring and protection requirements adjacent to critical infrastructure and landmarked buildings.
  • Describe utility re-location design and construction challenges.