The Bathtub
| Company type | Foundation structure |
|---|---|
| Industry | Construction, Civil engineering |
| Founded | 1967 |
| Headquarters | New York City , United States |
Area served | World Trade Center site |
| Products | Subterranean foundation, waterproofing walls |
The Bathtub designates the subterranean foundation zone at the location of the World Trade Center and its neighboring structures in New York City. This term originates from its deep, basin-like form with towering walls constructed to prevent water ingress rather than to contain water.
Description
Developed between 1967 and 1968, the Bathtub is an extensive, nearly rectangular excavation reaching down to the bedrock, encircled by reinforced concrete barriers serving as watertight dams to block water from the adjacent Hudson River. It encompassed almost the entire footprint of the original World Trade Center complex. The site was situated on artificial landfill extending into the Hudson River, with bedrock located approximately below. Manual water removal would have disturbed local groundwater levels and could have jeopardized the stability of nearby foundations, making this waterproof enclosure a critical engineering solution.
Spanning an area of , the Bathtub contains seven basement stories, accommodates the downtown terminal for the PATH rapid transit line, and includes sections of the preexisting New York City Subway's IRT Broadway–Seventh Avenue Line (). The South Tower was constructed around PATH tunnels that run through the foundation, enabling continuous transit operations during construction. The waterproofing walls measure thick and rise to a height of .
Excavated soil from the Bathtub’s construction was repurposed as landfill for Battery Park City, a technique also employed in building the foundation for Chicago's Willis Tower.
Multiple utility conduits and PATH trains pass through openings in the Bathtub walls. Presently, a corridor links Brookfield Place with the World Trade Center Transportation Hub.
Challenges
The initial bathtub walls relied on lateral support provided by the basement floors of the WTC. Following the collapse of the Twin Towers during the September 11 attacks, partial destruction of these floors raised concerns that debris removal operations might undermine wall stability. Such failure could have endangered recovery personnel, compromised adjacent structures, and caused flooding over a significant portion of the subway network. During cleanup efforts, substantial deterioration of these walls was detected, leading to an urgent installation of tiebacks anchored into bedrock to reinforce stability. Between 2006 and 2008, excavation and reconstruction efforts produced a new bathtub structure extending roughly underground.