• View from the observation floor of the new Freedon Tower

      View from the observation floor of the new Freedom Tower

Ground Zero revival of Lower Manhattan 11 Sep 2013
Shani Wallis, TunnelTalk
In this anniversary week of the terrifying events of September 11, 2001, there is much to remember and more to celebrate through the determined reconstruction of the World Trade Center Ground Zero site in Lower Manhattan.
Iconic Freedom Tower on the Manhattan skyline

Iconic Freedom Tower on the Manhattan skyline

Standing as a new icon on the skyline of New York City, the last sections of the spire of the new Freedom Tower were lifted into position in May and work continues on completing three other multi-storey buildings on the site. These surround the footprints and gardens of the two original skyline buildings which are preserved today, never to be built on again, as memorials to the ghastly events of 9/11 and those who lost their lives as a result.
New above-ground building work has served as a visual marker of progress, but there is equally as dramatic and inspiring work going on below the surface where a brand new transportation hub for subway and commuter trains, ferry and bus connections, and car parking and underground walkways is being built as the foundation of the reconstruction effort and as the focal point of a vast underground retail, commercial, entertainment and dining complex that will transform the environment of Lower Manhattan for visitors, citizens, and workers alike.
Often criticized for taking so long, the work underground is of tremendous scale and is yet to be revealed to the public. As each new floor of the towers was added and monitored by all passers by, the underground work will be of equal marvel when opened. In June this year, and some 11 years after a first visit in June 2002, TunnelTalk was privileged to be invited on an exclusive tour of the site and the underground works at Ground Zero to appreciate what is scheduled to be unveiled and opened in 2015.
Footprint of original buildings preserved as a memorial

Footprint of original buildings preserved as a memorial

Reconstruction programme
As owner of the previous buildings and of the site, the Port Authority of New York and New Jersey is managing a vast capital investment of near US$10 billion in reconstruction not only of the four new buildings but also of some 800,000ft2 (75,000m2) of underground space and the new transportation hub. After the traumatic clearing of the site, much time was taken over deciding exactly what would happen on the site and how it would be reconstructed. Once agreed, work started and has progressed night and day, every day to have the new buildings completed in the shortest time possible.
Magnificent underground building being constructed

Magnificent underground building being constructed

For the underground works, fortunately, and to avoid even further devastation, the original diaphragm walls installed as part of the 1967-1970 construction of the two original towers, the first use of slurry walls in the United States, and their underground car parking garages and subway and train stations, remained in tact. Creating a perimeter around the 16-acre site and to a depth of some five stories deep, these diaphragm walls remain as part of the new construction and new diaphragm walls have been installed to add further elements to the underground environment. This added also to the retail space in the underground complex and provides new walkways and accesses to the subway and railway stations at the bottom of the site and at up to five stories below the surface. The new WTC Transportation Hub concourse will incorporate stations and connections to 11 different subway lines, the Port Authority Trans-Hudson (PATH) commuter trains, the new Fulton Street Transit Center, an underground parking facility, Battery Park City Ferry Terminal, the World Trade Center Memorial Site, the new WTC tower buildings, the World Financial Center and the Winter Garden. It will represent the most integrated network of underground pedestrian and transport connections in New York City.
Plan of the 16-acre site and its new layout and sturctures

Plan of the 16-acre site and its new layout and sturctures

Architectural design of this new underground space was awarded to world renowned architect Santiago Calatrava of Spain, whose signature feature is brilliant white finishes. This trademark has been incorporated into the new WTC Hub, to create a dazzling environment.
The Hub design is based on a skylight feature at its heart. Called an 'oculus', Latin for eye and denoting a circular opening in the center of a dome or wall, above the oculus skylight will rise a distinctive, wing-like Vierendeel Truss structure as a landmark above the main underground mezzanine and concourse. At 365ft (112m) long, this main concourse will be incorporate 365,000ft2 of multi-level retail, restaurant and entertainment space as well as the start of underground walkways leading to other connections in Lower Manhattan including Wall Street. The Port Authority partnered with the international Westfield Group to develop, lease and operate the WTC retail space in the towers and in the Transit Hub.
When completed in 2015, the state-of-the-art World Trade Center Transportation Hub, will serve an estimated 250,000 commuters each day and millions of visitors from around the world per year.
  • Construction of the oculus concourse

    Construction of the oculus concourse

  • Construction of the oculus concourse

    Construction of the oculus concourse

  • Ceiling of the mezzanine level

    Ceiling of the mezzanine level

  • Upper level walkway

    Upper level walkway

  • Lower level walkway

    Lower level walkway

  • Retail space within the Transportation Hub

    Retail space within the Transportation Hub

  • Artists impression of the Vierendeel Truss skylight structure

    Artists impression of the Vierendeel Truss skylight structure

  • Artists impression of a connecting passageway

    Artists impression of a connecting passageway

Brilliant white finish of support structures in a main passageway

Brilliant white finish of support structures in a main passageway

  • Skylight structure at night

    Skylight structure at night

  • Working area within the station

    Working area within the station

  • 2002: TunnelTalk Editor at Ground Zero

    2002: TunnelTalk Editor at Ground Zero

References - From the Archive
PATH prepares for a new era - TunnelTalk, September 2002
Exchange Place turn around re-opens - TunnelTalk, May 2003

           

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