The World Trade Center 20 Years Later

As we approach the 20^th anniversary of 9/11, we can see how much progress has been made on rebuilding the site where the World Trade Center once was, before the September 11, 2001 terrorist attacks. For many who were charged with rebuilding, the past 20 years has been a process that involved not just sorting through what remained  but creating new structures that would not only commemorate the site, but add beauty to the New York skyline and be structurally stronger than the original.

Studio Daniel Libeskind World Trade Center Master Plan

The two World Trade Center hijacking attacks were not the only attacks on that day. Al-Qaeda terrorists hijacked a third plane that struck the Pentagon, that caused the building to partially collapse. A fourth hijacked plane was headed for Washington DC but crashed into a field as passengers struggled to regain control of the flight. A total of 2,996 people died in the four hijackings.

Seven architectural teams were invited to compete to design the masterplan for the site. Studio Daniel Libeskind, was chosen to do the masterplan, yet did not begin construction for another couple of years.

Concept sketches, Daniel Libeskind

Final plans included five skyscrapers designed by SOM, Richard Rogers, Fumihiko Maki and Norman Foster, with the memorial, museum, performing arts center and transport hub.

On July 4, 2004, a symbolic cornerstone was placed, but the building’s design of a Freedom Tower, was proposed by architect Daniel Libeskind. The design evolved and in 2005 architect David Child and Skidmore Owings & Merrill (SOM) took the lead, with Childs as design architect for buildings Seven and One, and Libeskind focused on the overall master plan for the site. Originally Libeskind had envisioned five skyscrapers in a semi-circle around a memorial at the original towers site.

Construction is both above and below ground level, as the 9/11 Memorial Museum which was completed first, features the underground slurry wall in Foundation Hall and parts of the original structure that comprise the museum.

One World Trade Center or 1WTC, is the central skyscraper of 104 stories, and boasts a 408-foot steel spire antenna. It is the tallest building in the U.S. as of May 10, 2013, when the final spire sections were put in place and the tower reached its full height of 1,776 feet. There was an exterior elevator hoist that was dismantled for the building’s official opening in November of 2014. From 2014 through 2015, many office workers moved into the over 3 million square feet of office space. By May 2015, the observation area on floors 100, 101, and 102 opened to the public.

Many design changes were afoot during these years and 2 World Trade Center underwent some of those changes. Norman Foster had his plans set from 2006 on, but new tenants (21^st Century Fox and News Corp.) signed up for 2WTC who brought in a new architect with new design. The Bjarke Ingels Group (BIG) presented a two-faced design with two personalities – the 9/11 Memorial side as corporate and sedate, while the street side that faces Tribeca is stepped and has a garden-like residential quality.

Foster + Partners are designing a proposed jagged skyscraper (center). Image by Foster + Partners

2WTC at a height of 1,323 feet is one of two skyscrapers still not completed. After a period of time in which the Danish studio BIG was brought on to design the building, the building design is now being reworked again by Foster + Partners.

3 World Trade Center was designed by Pritzker Prize-winning architect Richard Rogers and Rogers Stirk Harbour + Partners that employs a complex system of diamond-shaped braces. The upper floors offer unimpeded views of the World Trade Center site. It is the third tallest of the towers, with 80 stories in 1,079 feet. The grand opening was held in June 2018, and resembled closely Rogers’ original design.

4 World Trade Center, another tower, takes on a minimalist design created by Fumihiko Maki’s Maki and Associates, a well known architectural firm with footprints around the world. The signature of this skyscraper is that each corner rises to a different height, and the highest elevation is 977 feet. Maki had in mind to complete the spiral configuration of the towers on the World Trade Center site.

5WTC will be 900 feet tall and designed by US studio Kohn Pedersen Fox, with planned completion date in 2028.

World Trade Center Transportation Hub was envisioned by Spanish architect Santiago Calatrava, located between towers two and three. This inviting hub provides easy access to the World Financial Center (WFC), ferries, as well as 13 subway lines. The building opened to the public in March 2016 and construction began in September 2005.

The World Trade Center Transportation Hub by Santiago Calatrava opened in 2016. Photo by Hufton + Crow

Much has been written about the National 9/11 Memorial Plaza. It is described by some as the “heart and soul” of the World Trade Center site. Construction began in March of 2006. Architect Michael Arad designed two 30-foot waterfall memorials in the exact locations of the fallen twin towers. These structures, “”Reflecting Absence,” was the first design to break the plane between above and below ground as water drops toward the broken foundations of the fallen skyscrapers then moves to the 9/11 Memorial Museum below ground.  US studio Davis Brody Bond designed the underground museum.

The steel and glass entry to the National September 11 Memorial Museum, which opened May 21, 2014, before any of the other buildings,  is the only above-ground structure on the 9/11 Memorial Plaza, located near the memorial waterfalls. The entry is a glass atrium where visitors see two steel columns salvaged from the original twin towers. There is a Survivors Staircase and more steel beams from the twin towers, plus original artifacts. Meticulous detail was taken with this structure and the incorporation of pieces of the actual old structure with emotional impact taken into account. I’m told it evokes a special feeling of reverence to be present in the space and reflect on and honor those who lost their lives so tragically that day.

Tags: 3D cities, AEC, architects, architecture, BIM, building, collaboration, construction, design, engineering

Categories: 2D, 3D, AECCafe, collaboration, construction, construction project management, infrastructure

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