1 World Trade Center

One World Trade Center (formerly known as Freedom Tower) is the main building of the new World Trade Center under construction in Lower Manhattan in New York City, USA. The tower will be located in the northwest corner of the 16-acre (65,000 m²) World Trade Center site, bound by Vesey, West, Washington and Fulton streets. Construction on below-ground utility relocations, footings, and foundations for the 1776 ft Freedom Tower began on April 27, 2006. On December 19, 2006, the first steel columns were installed in the building's foundation. Three other high-rise office buildings are planned for the site along Greenwich Street, and they will surround the World Trade Center Memorial, which is under construction. The area will also be home to a museum dedicated to the history of the site.

On March 26, 2009, the Port Authority said that the building will be known as 'One World Trade Center'.

History
Following the destruction of the World Trade Center towers in the September 11 attacks, there was much debate regarding the future of the World Trade Center site. Proposals began almost immediately, and by 2002, the Lower Manhattan Development Corporation organized a competition to determine how to use the land. Public rejection of the first round of designs, the "Preliminary Design Concepts," led to a second, more open competition in December 2002, the "Innovative Design Study," in which a design by Daniel Libeskind was selected. This design went through many revisions, largely because of disagreements with developer Larry Silverstein, who held the lease to the World Trade Center site on September 11, 2001.

A final design for the tower was formally unveiled on June 28, 2006. To satisfy security issues raised by the New York City Police Department a 187 foot (57 m) concrete base was added in April of that year. The final design included plans to clad the base in glass prisms to address criticism that the base looked like a "concrete bunker." Contrasting with Libeskind's plan, the final design tapers the corners of the base outward as they rise. Its designers stated that the tower will be a "monolithic glass structure reflecting the sky and topped by a sculpted antenna." Commenting on a completion date, Larry Silverstein stated "By 2012 we should have a completely rebuilt World Trade Center more magnificent, more spectacular than it ever was." On April 26, 2006, the Port Authority of New York and New Jersey approved a conceptual framework that enabled foundation construction to begin while a formal agreement was drafted on the following day, the 75th anniversary of the opening of the Empire State Building. Construction began with a formal ceremony that took place when the construction team arrived. It is projected that the building's topping out will occur in 2011. The building is projected to be ready for occupancy at some point in 2012.

Architecture
Many remaining vestiges of the concepts drawn from the 2002 competition have since been discarded. 1 WTC will now consist of simple symmetries and a more traditional design intended to bear comparison with selected elements of the existing New York skyline. There will now be a central spire drawing from precedents such as the Empire State Building and the Chrysler Building (and also visually reminiscent of Tower 1 of the old World Trade Center) rather than an off-center spire intended to echo the Statue of Liberty.

"Freedom Tower will be a symbol of the entire project, as well as marking the memorial, and it occupies a very important piece of New York City property: the sky. We really wanted our design to be grounded in something that was very real, not just in sculptural sketches. We explored the infrastructural challenges because the proper solution would have to be compelling, not just beautiful. The design does have great sculptural implications, and we fully understand the iconic importance of the tower, but it also has to be a highly efficient building. The discourse about Freedom Tower has often been limited to the symbolic, formal and aesthetic aspects but we recognize that if this building doesn't function well, if people don't want to work and visit there, then we will have failed as architects."

Design
1 WTC's program includes 2.6 million square feet (241,000 square meters) of office space, as well as an observation deck, world-class restaurants, parking, and broadcast and antenna facilities, all supported by both above and below-ground mechanical infrastructure for the building and its adjacent public spaces. Below-ground tenant parking and storage, shopping and access to the PATH and subway trains and the World Financial Center are also provided.

An 80-foot-high (24 m) public lobby topped by a series of mechanical floors form a 200-foot-high (61 m) building base. 69 tenant floors rise above the base to 1,120 feet (341 m) elevation. Mechanical floors, two floors to be occupied by the Metropolitan Television Alliance, restaurants and observation decks culminate in an observation deck and glass parapet that mark 1,362 feet (415 m) and 1,368 feet (417 m) respectively — the heights of the original Twin Towers. A shrouded antenna structure supported by cables, engineered by Schlaich Bergermann & Partner rises to a total height of 1,776 feet (541 m), which is symbolic of the year the United States Declaration of Independence was signed (July 4, 1776).

The tower rises from a cubic base whose square plan—200 feet by 200 feet—(61 m by 61 m) is almost as wide as the 208 feet (63 m) Twin Towers. The base is clad in more than 2,000 pieces of prismatic glass; each measures 4 feet by 13 feet 4 inches (1.21 m by 4.06 m) with varying depths. It has been designed to draw upon the themes of motion and light; a shimmering glass surface drapes the tower's base and imparts a dynamic fluidity of form whose appearance will reflect its surroundings. Just as the rest of the building, the base will serve as a glowing beacon. Cable-net facades on all four sides of the buildings, again designed by Schlaich Bergermann, measure 60 feet (18 m) high and range in width from 30 feet (9 m) on the east and west sides (for access to the restaurant and observation deck, respectively) to 50 feet (15 m) on the north side and 70 feet (21 m) on the south for primary tenant access, activate the building at street level.

As the tower itself rises from this cubic base, its square edges are chamfered back, transforming the square into eight tall isosceles triangles in elevation, or an elongated square antiprism. At its middle, the tower forms a perfect octagon in plan and then culminates in a glass parapet (elevation 1,362 feet (415 m) and 1,368 feet (417 m)) whose plan is a square, rotated 45 degrees from the base. A mast containing an antenna for television broadcasters—designed by a collaboration between SOM, artist Kenneth Snelson (who invented the tensegrity structure), lighting designers and engineers—and secured by a system of cables, rises from a circular support ring, similar to the Statue of Liberty's torch, to a height of 1,776 feet (541 m). The spire will be an intense beam of light that will be lit at night and will likely be visible over a thousand feet (305 m) into the air above the tower. New York City is a suitable place to set such a light pointing towards the sky without complaints of light pollution by astronomers, as the night sky in locations near New York City is already far too bright for serious astronomical observers.

Other new safety features will include 3 feet (90 cm) thick walls for all stairwells, elevator shafts, risers, and sprinkler systems; extremely wide "emergency stairs"; a dedicated set of stairwells exclusively for the use of firefighters; and biological and chemical filters throughout its ventilation system. The building will no longer be 25 feet (7.6 m) away from West Street—with the redesign and smaller base (the same width and length now as each of the previous towers), 1 WTC will average 90 feet (27 m) away from the street. At its closest point, West Street will be 65 feet (20 m) away. The windows on the side of the building facing in this direction will be equipped with specially tempered blast-resistant plastic, which will look nearly the same as the glass used in the other sides of the building.

"Ultra-clear" glass, as opposed to reflective or tinted glass, is proposed for the tower's windows. This will benefit internal daylight propagation; however, at this stage it is unclear how the corresponding issue of solar heat gain will be addressed. 1 WTC will be green in several ways. Although the roof area of any tower is comparatively limited, the building will implement a rainwater recycling scheme involving rainwater collection. 1 World Trade Center has received Gold Certification by Leadership in Energy and Environmental Design.

"Its structure is designed around a strong, redundant steel moment frame consisting of beams and columns connected by a combination of welding and bolting. Paired with a concrete-core shear wall, the moment frame lends substantial rigidity and redundancy to the overall building structure while providing column-free interior spans for maximum flexibility."

Like all of the new facilities at the World Trade Center site, the 1 World Trade Center will be heated by steam, with limited oil or natural gas utilities located on site.

Height
The roof of the top floor of 1 WTC will be 1362 ft, the same as 2 World Trade Center. A six feet parapet on top of the roof will bring the building's height to 1368 ft, the same as 1 World Trade Center. If the spire and antenna height (the criteria of two categories of the Council on Tall Buildings and Urban Habitat) are included, 1 WTC will stand at a symbolic 1776 ft, marking 1776, the year of the signing of the American Declaration of Independence. 1 World Trade Center was originally planned to be the tallest building in the world, but will no longer obtain this title, as the Burj Dubai has already broken the record for the tallest building at 2684 ft.

The World Trade Center's South Tower had an outdoor rooftop observation deck at 1,377 feet (420 m) and another indoor observation deck at 1,310 feet (399 m). 1 WTC's indoor observation deck, at a height of 1,265 feet (386 m), will not be as high as either of the observation decks destroyed in the South Tower.

Space allotment
As revealed on June 28, 2006, 1 WTC will have a top floor denoted as 102, though the total number of floors is 82 (possibly with some uncounted floors). This is because the first office floor of the building atop the tall base will be designated as Floor 20. There are 69 office floors atop the base, ending at Floor 88, above which would be broadcasting space on the 89th and 90th floors. Three stories of mechanical space take up a floor count of 9. Finally, a restaurant will take up Floors 100 and 101, and the observation deck is at Floor 102. Six additional floors of mechanical space exist above to Floor 108. Additionally, roughly 55000 sqft of retail space will exist below-grade, part of an overall 500000 sqft of retail space to be spread throughout the site both in the below-grade concourses and on the lower floors of Towers 2, 3, and 4.

Floor breakdown
The following is a breakdown of floors as noted by SkyscraperPage.com:


 * 1-19 - tower base (including 80 ft tall lobby and 3 mechanical floors)
 * 20-63 - offices
 * 64 - skylobby
 * 65-88 - offices
 * 89-99 - mechanical floors
 * 100-102 - observation deck and other public facilities to be announced
 * 103-108 - mechanical floors

Note that these official designations may not correspond to actual floor levels (in particular at the base).

Tenants
The State of New York has agreed to a 15 year lease of 415,000 square feet (38,550 square meter) of space inside 1 WTC, with an option to extend the term of the lease and occupy up to 1,000,000 square feet (92,900 square meter). The General Services Administration (GSA) has agreed to lease approximately 645,000 square feet (59,900 square meters) of space, New York State's Office of General Services (OGS) plans to lease approximately 412,000 square feet (38,275 square meters) of space and the China Center expects to lease approximately 190,000 square feet (17,650 square meters) in the tower. In April 2008, the Port Authority announced that it was seeking a bidder to operate an 18000 sqft observation deck on the tower's 102nd floor.

2004 to 2006
The symbolic cornerstone of 1 WTC was laid down in a ceremony on July 4, 2004 and further construction of the tower was stalled until 2006. The cornerstone was temporarily removed from the site on June 23, 2006. The project had been delayed due to acrimonious disputes over money, security, and design but the last major issues were resolved on April 26, 2006 with a deal between developer Larry Silverstein and the Port Authority of New York and New Jersey. During the summer of 2006, test explosives were detonated at the World Trade Center construction site, testing the use of charges to clear bedrock for 1 World Trade Center’s foundation. Three to four controlled explosions per day followed on alternating weekdays for approximately two months after.

2006 to 2007
On November 18, 2006, 400 cubic yards (306 cubic meters) of concrete were poured onto the foundation of the 1 WTC carried by as many as 40 trucks. On December 17, 2006, a ceremony was held in Battery Park City, with the public invited to sign a 30 feet (9 m) steel beam. This beam, the first to be installed, was welded on to the Freedom Tower's base on December 19, 2006. On January 9, 2007 a second set of beams was welded to the top of the first set.

February 2007 estimates put the cost for construction of 1 WTC at $3 billion, or $1,150 per square foot ($12,380 per square meter). Approximately $1 billion of insurance money recouped by Silverstein is slated for construction of the Freedom Tower. The State of New York is expected to provide $250 million toward construction costs, and the Port Authority would finance another $1 billion for 1 WTC, through bonds.

In 2007, Tishman Construction Corporation of New York completed a row of steel columns at the perimeter of the construction site. Two tower crane bases were erected, each base containing a functioning luffing-jib tower crane. By the end of 2007, the tower’s footings and foundations were nearly complete.

2008
In January 2008, two construction cranes were placed at the construction site of 1 WTC. The tower's concrete core began the same year on the basement floors, but began rising in the first months of 2008. By February 22, 2008, 9,400 tons of the nearly 50,000 tons of steel necessary for the Freedom Tower had been ordered. By March 13, 2008, the steel for the tower had reached 70 ft high, 10 ft below street level. From late March through early April, a 40 foot (12 m) tall mockup of a section of the tower's wall with 24 windows was tested by Construction Consulting Laboratory West in Ontario, California. The two weeks of testing were done to make sure the all-glass exterior of the tower will be able to withstand earthquakes and extreme weather conditions. Testing also took place on another full-scale mockup in a rural area south of Albuquerque, New Mexico. Both mockups passed the tests. In the middle of April, a batch of concrete had to be replaced after it failed a stress test April 15.

On May 17, 2008, the tower's steel breached street level when new sections were bolted to two of the 24 jumbo steel columns marking the building's footprint. The new column sections brought the height of the structure up to 15 ft above street level. In June, the chamfered steel skeleton of the tower's concrete base had begun to take shape. By the end of the month, the concrete had been poured for the floor of the tower's basement level B3. In his June 30, 2008 World Trade Center Rebuilding Assessment to New York Governor David Paterson, Port Authority executive director Chris Ward noted that "approximately 90 percent of the Freedom Tower contracts have been bid or are ready to award." By August, 1 WTC had reached above street level. During its September 16th meeting, the Port Authority board approved contracts for security and building management systems; fully 95 percent of contracts needed to complete the tower had now been signed. The $20 million security contract includes sophisticated video analysis in which computers would alert security personnel to abnormal situations automatically. On 10 October, Collavino Construction poured an additional 520 cubic yards of concrete for the tower's concrete core, which was thereby raised from four inches (102 mm) below street level to 13 ft, eight inches (203 mm)  above street level.

2009
On February 11, 2009, the Port Authority of New York and New Jersey website posted a picture of 1 WTC showing that it was 105 ft above street level.

Future progress
1 WTC is expected to reach rooftop level by the end of 2010 with topping out expected by 2011. However in an October 2, 2008 follow-up report by Ward, the estimated completion of the tower was pushed back to some time between the second and fourth quarter of 2013 with a total budget of $3.1 billion and the use of 46,000 tons of steel.

Controversy
The design of 1 WTC has generated some controversy due to the limited number of floors in the previous design (82) that were designated for office space and other amenities. The floor limit was imposed by Silverstein, who expressed concern that higher floors would be a liability in a major accident or terrorist attack. In a subsequent redesign, the highest occupiable space became comparable to the World Trade Center.

Soon after the destruction of WTC Towers 1 and 2 there was a persistent public demand to rebuild the previous twin towers instead of building a single tower. Ian Simpson Architects designed twin towers but the final 1 WTC design was more favored by officials. Developer Donald Trump also unveiled a twin design, but he was not affiliated with the official project. Former New York Governor George Pataki faced accusations of cronyism for supposedly using his influence to get the winning architect's bid picked as a personal favor for a close friend.

The base of the tower (fortified because of security concerns) has also been a source of controversy. A number of critics (notably Derek Murdoch in the National Review) have suggested that it is alienating and dull, and reflects a sense of fear rather than freedom, leading them to dub the project "the Fear Tower." Nicolai Ouroussoff, the architecture critic for the New York Times, calls the tower base decorations a "grotesque attempt to disguise its underlying paranoia".

Larry Silverstein
Larry Silverstein of Silverstein Properties, the leaseholder and developer of the complex, will retain control of the surrounding buildings, while the Port Authority gets full control of the tower itself. Silverstein signed a 99-year lease for the World Trade Center site in July 2001. Silverstein's insurance payout has been a subject of public discourse, as he maintained that the two planes constituted two separate attacks and sued for an extra $3.5 billion. Silverstein has pledged to support the reconstruction and remains actively involved in most aspects of the redevelopment process.

David Childs
David Childs, one of Larry Silverstein's favorite architects, initially came on board thanks to Silverstein's insistence, and developed a proposal for 1 WTC in collaboration with Daniel Libeskind, a design which was revised in May 2005 to address security concerns. He is the project architect of the new 1 WTC, and is responsible for overseeing the day-to-day design development from rough inception to final completion.

Daniel Libeskind
Daniel Libeskind won the invitational competition to develop a master plan for the World Trade Center's redevelopment in 2002. He included an initial proposal for the design of 1 WTC, a building with aerial gardens and windmills with an off center spire. It was also Libeskind who denied a request to place the tower in a more rentable location next to the PATH station and instead placed it a block west because in profile it would line up and resemble the Statue of Liberty. Although these designs have since been changed, his contributions continue to shape the design and development at Ground Zero, as they are revised to meet economic and security realities.

Dan Tishman
Dan Tishman, along with his father John Tishman, builder of the original World Trade Center, is leading the construction management effort for Tishman Realty & Construction, the selected builder for 1 WTC.