YMCA Prospect Park - Sidewalk Replacement


357 Ninth Street, Prospect Heights, Brooklyn 


This DOT sidewalk vault replacement was complicated by the fact that it was over a NYCTA subway tunnel, which required strict compliance with DOT, NYCTA and the Department of Buildings requirements. The necessity to re-route pedestrian and member foot traffic while maintaining building egress also magnified the project’s complexity.

In addition, elevation challenges discovered during the demolition process required technical coordination with the project’s engineer.


CIP worked closely with the YMCA’s Engineering/Architectural team to develop a successful construction and logistics strategy that included:

  • Devising a creative scaffold system to remove existing concrete and steel while minimizing the impact to the building’s main electrical and boiler plant.
  • Constructing scaffolding to minimize any loading to the subway tunnel roof while supporting the transportation of demolition spoils.
  • Coordinating with the YMCA team to precisely pre-order and fabricate the detailed steel substructure for the vault.
  • Implementing a “Manhattan slab” scenario that required differing elevations for the beams and girders.
  • Designing a new water proofing system with a 20-year warranty to preserve the new vault structure.


The quick response and work of the YMCA engineers and CIP’s structural team brought in the project on-time and on-budget, and served as the basis for the project’s second phase, saving the client considerable time and expense.

This is one of several projects CIP has done for the YMCA of Greater New York.

New York City Power Group