There is no doubt that the attacks that occurred throughout the United States on September 11, 2001 (twelve years today) changed the course of history. The Twin Towers, located in New York City, collapsed two hours after the first plane hit the north tower. The death toll for these attacks totalled over 3000 (History Channel).
To pay tribute to the victims, plans were made to construct a memorial complex on the site of the old Trade Centers. This complex features five new skyscrappers, a 9/11 memorial and museum, a World Trade Center transportation hub, retail space, and a performing arts centre (World Trade Center). The extensive plans have involved some of the most famous architects, artists and urban developers of our time, including: Santiago Calatrava, David Cholds, Norman Foster, Frank Gehry, Daniel Libeskind, Fumihiko Maki and Richard Rogers (World Trade Center).
The memorial features two 16-acre reflecting pools which are set in the original footprints of the two towers. The largest man-made waterfalls in North America are located in the centre of these pools, and the names of the victims are written around the pool’s edges.
For Every Action, There is an Equal Larger and Opposite Reaction
In addition to the memorial, plans were made to build five new skyscrapers. One World Trade Center, sometimes incorrectly referred to as Freedom Tower (Wall Street Journal), will be the tallest building in the western hemisphere, and the fourth tallest building in the world upon completion. The roof top has a height of 1368 ft (417m), identical to the height of the original North Tower. However, the steel spire situated at the top of the building bring the total height to 1776 ft (541 m). This acts as a symbolic reference to the date that the United States signed the Declaration of Independence, separating the colony from the British Empire.
The structure is composed of a concrete core surrounded by a steel structure. As a result, the tower acts like a ‘building within a building’, attaining a level of safety which far surpasses the current requirements in building codes. Steve Plate, the director of World Trade Center construction for the Port Authority of New York and New Jersey, stated, “The core walls aren’t sheetrock like the original towers, they’re more than 6 feet of concrete in places. We’re rewriting the book on security for office towers.” In addition to this, the podium at the base of the building consist of a 187 ft tall by 200 ft wide concrete slab, increasing the towers safety. (Popular Mechanics).
Once completed, this building will play host to 69 office floors, two television broadcasting floors, two restaurants, an observation deck, and a glass-metal parapet (World Trade Center). The construction of the tower, which began in 2006, is expected to be completed in early 2014.
Green Reaches New Heights
One of the most important features of the new landmark is the achievement of a LEED Gold certification. This has been attained through the use of various green technologies. The 57th floor will play host to two 25,000 gallon (94,600 L) rainwater collection tanks, which will be used for the buildings operational needs. In addition, the toilets are shaped in a way to increase the velocity of the water flushing, reducing the amount of water per flush. According to Steven Plate, “It not just helps the environment. It also saves a lot of operational costs.” (MSNBC News)
Some other ‘green’ features include: the use of recycled debris and materials during construction, an increase in the use of natural light, and an LED backlight system for the podium which is both cost-effective and creates less heat energy,
However, the ‘green’ emphasis has lead to construction costs of almost $4 billion (US), making it the most expensive office tower ever built (Wall Street Journal). Despite this, the significantly lowered operating costs and energy usage make the project economical from a life cycle perspective. For more information about the LEED program, see my previous post entitled “LEED-ing the Way to a Better Future“.
Perseverance
Before the final steel beam was lifted into place for One World Trade Center, President Barrack Obama inscribed, “We remember. We Rebuild. We come back stronger.” (Telegraph) The symbolism behind this is quite strong, and personify’s the project as more than just a building; it represents the resiliency of the American people, and acts as a tribute to those that lost their lives in the horrific attacks.
It is important that people do not forget the past. History can teach us important lessons about the future, and can be one of the most important tools in making the world a better place. This tower stands as a testament, not only to those who lost their lives, but to the thousands of men and women who have worked on building from the ashes. The lessons learned from the collapsed towers are studied all across the globe, and have helped develop new techniques for creating stronger, more resilient structures. It is believed that this will create a new standard for high rise construction, ensuring that the events of September 11 will never again occur.
To see additional construction photos, visit the Structural Digest Gallery.
