The World Trade Center “Bathtub”, a Case History

In 1967 the Port Authority of New York and New Jersey (PANYNJ) undertook the construction of the World Trade Center (WTC) diaphragm (slurry) walls, installation of the lateral support system and the excavation of the site, commonly referred to as the “Bathtub”. The work took two years to complete. In 2001 the City of New York undertook the re-excavation of the site after the terrorist attacks. The recovery work took eight months to complete. When the World Trade Center Recovery Effort officially concluded on May 30, 2002, reconstruction was already underway. The Port Authority of New York and New Jersey had already completed its plans for the reconstruction of the Port Authority Trans Hudson (PATH) tubes and a temporary station. New York City Transit (NYCT) started the reconstruction of the Interboro Rapid Transit (IRT) 1 and 9 line tunnel in Greenwich Street after having already restored service on the Brooklyn Manhattan Transit (BMT) N and R lines in Church Street. Silverstein Properties started reconstruction of World Trade Center 7 (WTC 7) and the construction of the Consolidated Edison (Con Ed) transformer vaults located within the base of the WTC 7 building. These replacement structures, when combined with other existing structures such as the slurry wall, affect future development of the World Trade Center site. This paper will discuss the original construction of the “Bathtub”, the recovery effort, changes at the site since May 2002, conditions which will affect construction in the future and proposals for new construction

Times Square Redevelopment: A Below Grade View

The paper describes the design and construction of the foundations for two new high-rise structures in New York City (NYC). The sites are located in the heart of Times Square, bound by 42nd Street to the north, 41st Street to the south, and Broadway to the east. Below grade, active subways and subway stations abut the sites, extending as much as 50 feet into the property. The work involved the demolition of existing structures, excavation of debris and rock to depths exceeding 30 feet below grade, bracing adjacent subway structures around the site, installing high capacity caissons immediately adjacent to the deeper subways, and adapting existing foundations to accommodate the new building foundations. Of particular interest is the preservation of the adjacent historic New Amsterdam Theatre that included vibration and settlement monitoring during construction. Due to the unique site constraints, close collaboration of the Engineers with the Owner, Foundation Contractors, and New York City Transit (NYCT) was required. Innovative solutions for the foundation design were applied to accommodate several construction stages and allowed the projects to be completed without adversely affecting the subways, pedestrian traffic or the historic theatre. The projects received several awards, including the 2001 New York Association of Consulting Engineers (NYACE) Platinum Excellence Award in Geotechnical Engineering and Historical Preservation Plan, and the 2003 NYACE Gold Engineering Excellence Award

Underground engineering for sustainable urban development

Underground infrastructure is essential for delivery of services that support a strong urban economy and high quality of life. However, current underground engineering practice and education do not promote the interdisciplinary and systems-oriented development approaches that support urban sustainability. Further, lack of long-term investment and coordination of underground development and engineering at most levels of U.S. government curtails cost effectiveness and sustainability and jeopardizes future U.S. technological leadership in underground engineering. Ad hoc development of underground infrastructure projects adversely affects sustainability and increases infrastructure costs. Comprehensive lifecycle planning of underground space as part of a three-dimensional, integrated above- and belowground urban system could reduce costs and increase sustainability. Better analysis and design approaches that facilitate long-term asset management also support sustainability. Retrospective cost analyses of existing infrastructure can inform future triple-bottom-line cost assessments and quantify the economic, social, and environmental benefits of different infrastructure choices. Targeted long-term research, better interdisciplinary education and training for underground engineers, and greater societal awareness of the importance of the underground are needed to maximize the contributions of underground engineering to sustainability. This paper summarizes conclusions from the National Research Council report Underground Engineering for Sustainable Urban Development (2013; http://www.nap.edu/catalog.php?record-id=14670). \ua9 2014 American Society of Civil Engineers