One World Trade Center

One World Trade Center (1 World Trade Center), more simply known as 1 WTC and formerly known as the Freedom Tower, is the lead building of the new World Trade Center complex in Lower Manhattan in New York City. The 105-story supertall skyscraper is being constructed in the northwest corner of the World Trade Center site, occupying the location where the original 8-story 6 World Trade Center once stood. The north side of the tower runs between the intersection of Vesey and West streets on the northwest and the intersection of Vesey and Washington streets on the northeast, with the site of the original North Tower/1 WTC offset to the south. Construction on below-ground utility relocations, footings, and foundations for the building began on April 27, 2006. On March 30, 2009, the Port Authority confirmed that the building would be known by its legal name of One World Trade Center, rather than the colloquial name, Freedom Tower. Upon its completion in 2013, One World Trade Center will be the tallest building in the United States and one of the tallest in the world, with its radio antenna reaching a symbolic height of 1776 ft in reference to the year of American independence.

Along with One World Trade Center, the new World Trade Center site will feature three other high-rise office buildings, located along Greenwich Street, and the National September 11 Memorial & Museum, located at the foot of One World Trade Center. The construction is part of an effort to memorialize and rebuild the original World Trade Center complex, which was destroyed during the terrorist attacks of September 11, 2001.

History
Following the destruction of the World Trade Center on September 11, 2001, there was much debate regarding the future of the World Trade Center site. Proposals began almost immediately, and by 2003, 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, 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 "Freedom Tower" was formally unveiled on June 28, 2005. To satisfy security issues raised by the New York City Police Department, a 187 ft 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", although these plans later proved unworkable, and were replaced by a simpler facing. Contrasting with Libeskind's plan, the final design tapers octagonally as it rises. Its designers stated that the tower will be a "monolithic glass structure reflecting the sky and topped by a sculpted antenna." Larry Silverstein commented in 2006 on a planned completion date: "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, and a formal agreement was drafted on the following day, the 75th anniversary of the opening of the Empire State Building. Construction began in May with a formal ceremony that took place when the construction team arrived. The building's topping out has been projected for early 2012, and it is expected to be ready for occupancy in 2013.

In 2009, the Port Authority changed the name of the building from "Freedom Tower" to "One World Trade Center," stating that this name was the "easiest for people to identify with."

Architecture
Many remaining vestiges of the concepts drawn from the 2002 competition have since been discarded. One World Trade Center 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.

According to David Childs of Skidmore, Owings and Merrill, the project architect of the new 1 World Trade Center, the tower:

Design
One World Trade Center's design includes 2600000 sqft of office space, as well as an observation deck, 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.

A 65 ft high public lobby, topped by a series of mechanical floors, form a 200 ft-per-side visual cubic base to the tower. The next 69 floors, providing tenant office space, rise above the base to an elevation of 1150 ft. Mechanical and observation floors culminate in a rooftop observation deck at 1362 ft with a glass parapet extending to 1368 ft — 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 1776 ft, which is a tribute to the year the United States Declaration of Independence was signed. A plan to build a restaurant near the top of the tower was abandoned as logistically too difficult.

The 200 ft sides at the square footprint of the base are almost as wide as the 208 ft square of the original Twin Towers. The 185 ft window-less concrete base was added to the design in 2005 to increase strength to withstand a truck bomb, and the building was moved further from the West Side Highway. The design was criticized as uninviting and fortress-like. To address this, the base was to be clad in more than 2,000 pieces of prismatic glass designed to draw upon the themes of motion and light. This proved unworkable, however, and a simpler glass-and-steel façade is planned for the base. Cable-net glass façades on all four sides of the building for the higher floors, designed by Schlaich Bergermann, will be consistent with the other buildings in the complex. They measure 60 ft high and range in width from 30 ft on the east and west sides (for access to the observation deck) to 50 ft on the north side and 70 ft on the south for primary tenant access. The curtain wall is being manufactured and assembled in Portland, Oregon by Benson Industries using glass made in Minnesota by Viracon.

As the tower 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. Near its middle, the tower forms a perfect octagon in plan and then culminates in a glass parapet (elevation 1362 ft and 1368 ft) whose plan is a square, rotated 45 degrees from the base. A mast containing the antenna for television broadcasters – designed by a collaboration among SOM, artist Kenneth Snelson (who invented the tensegrity structure), lighting designers and engineers – is secured by a system of cables, and rises from a circular support ring, similar to the Statue of Liberty's torch, to a height of 1776 ft. Above the mast will be an intense beam of light that will be lit at night and will likely be visible over 1000 ft into the air above the tower. Just south of the building is the 9/11 memorial, featuring two large square waterfalls which are located on the exact footprints of the original twin towers.

One World Trade Center, along with the rest of the buildings in the new World Trade center complex, will be environmentally friendly in several ways. Although the roof area of any tower is comparatively limited, the building will implement a rainwater collection and recycling scheme for its cooling systems. The building's fuel cell will generate 4.8 million watts (MW), and waste steam will help generate electricity. The windows are made of an ultra-clear glass which allows maximum daylight to pass through while keeping out heat, thereby reducing energy costs. Like all of the new facilities at the World Trade Center site, One World Trade Center will be heated by steam, with limited oil or natural gas utilities located on site. One World Trade Center is expected to receive a Leadership in Energy and Environmental Design (LEED) Gold Certification.

Height
The roof of the top floor of One World Trade Center will be 1368 ft, including a 33ft 4in parapet. This height is the same as the original One World Trade Center. With its spire height (the criteria of two categories of the Council on Tall Buildings and Urban Habitat), One World Trade Center will stand at 1776 ft, a figure symbolic of the year of the United States Declaration of Independence.

With a structural height of 1776 ft, One World Trade Center will surpass the 1671-foot (509-meter) height of Taipei 101 to become the world's tallest all-office building and the tallest building in the Americas, surpassing the Willis Tower (also known as the Sears Tower) in Chicago. However, its roof height will still be 83 ft shorter than the Willis Tower. At the time of its completion, One World Trade Center will be the third-tallest skyscraper in the world, behind the Burj Khalifa and the Mecca Royal Hotel Clock Tower, and the 8th-tallest structure of any kind in the world.

The Chicago Spire (with a planned height of 2000 ft) was expected to exceed the height of One World Trade Center, but its construction was canceled in 2009 due to financial difficulties. A new 2,000-foot tower is currently planned for construction as part of Chicago's Old Post Office Redevelopment project, although its funding has yet to be fully secured.

Space allotment and security
One World Trade Center will have a top floor denoted as 105. The first office floor of the building atop the 200 ft square base will be designated as Floor 20, and the building will have 74 usable above-ground floors. Sixty-nine floors will be designated as office floors. 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.

In addition to the protection offered by the reinforced, window-less base, a number of other design and security features are planned for the building. New safety features will include 3 ft thick reinforced concrete walls for all stairwells, elevator shafts, risers, and sprinkler systems; extra-wide, pressurized stairwells; 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 ft away from West Street, as the Twin Towers were; at its closest point, West Street will be 65 ft 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. The seventy elevators and 9 escalators for 1 World Trade Center will be provided by ThyssenKrupp, with steel counterweights supplied by Concord Steel. The Port Authority has stated: "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."

Along with optimum safety design, new security measures will also be implemented. All vehicles will be screened before they enter the site via the underground roadway, including for radioactive materials. Visitors to the September 11 memorial will undergo airport-style screening. 400 closed-circuit surveillance cameras will be placed in and around the site, with live camera feeds being monitored around the clock by the NYPD. A computer system will use video-analytic computer software designed to detect potential threats such as unattended bags and retrieve images based on descriptions of terror or other criminal suspects. New York City and Port Authority police will patrol the site.

Owners and tenants
One World Trade Center is owned principally by the Port Authority of New York and New Jersey. Around 5% equity of the building was sold to the Durst Organization in exchange for an investment of at least US$100 million. The Durst Organization assisted in supervising the building's construction, and manages the building for the Port Authority, having responsibility for leasing, property management and tenant installations.

Government tenants
In 2006, the State of New York agreed to a 15-year lease of 415000 sqft of space inside 1 WTC, with an option to extend the term of the lease and occupy up to 1000000 sqft. The General Services Administration (GSA) initially agreed to lease approximately 645000 sqft of space, and New York State's Office of General Services (OGS) planned to lease approximately 412000 sqft of space. However, in July 2011, the GSA ceded most of its leased floor space to the Port Authority, and the OGS withdrew from the lease agreement. 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.

China Center
The building's first lease was announced on March 28, 2009, as a joint project between the Port Authority of New York and New Jersey and Beijing-based Vantone Industrial Co. A 190810 sqft "China Center", combining business and cultural facilities, is to be located between floors 64 and 69, to represent Chinese business and cultural links to the United States, and to serve US companies that wish to conduct business in China. Vantone Industrial's lease is for 20 years and 9 months.

Condé Nast
On August 3, 2010, Condé Nast signed a tentative agreement to move the headquarters and offices of its 18 magazines into One World Trade Center, occupying up to 1000000 sqft of the building. On May 17, 2011, Condé Nast reached an agreement with the Port Authority, securing a 25-year lease with an estimated value of $2 billion. On May 25, 2011, Condé Nast finalized the lease agreement, leasing 1,008,012 sqft of office space on floors 20–41 of the tower. The lease also covers 30,000 sqft of usable space in the podium and below grade floors, for mail, messenger services, and storage use.

2004–2007
The symbolic cornerstone of One World Trade Center was laid down in a ceremony on July 4, 2004, but further construction of the tower was stalled until 2006. The cornerstone was temporarily removed from the site on June 23, 2006. The project was delayed due to acrimonious disputes over money, security and design, but the last major issues were resolved on April 26, 2006, when a deal was struck between developer Larry Silverstein and the Port Authority of New York and New Jersey. For two months during the summer of 2006, explosives were detonated at the World Trade Center construction site, testing the use of charges to clear bedrock for the building's foundations.

On November 18, 2006, 400 cuyd of concrete were poured onto the foundation of the One World Trade Center, 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 ft steel beam. This beam, the first to be installed, was welded onto the building's base on December 19, 2006.

On January 9, 2007, a second set of beams was welded to the top of the first set. 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.

2008–2009
In January 2008, two construction cranes were moved into the construction site. The tower's concrete core began rising in the first months of 2008. By February 22, 2008, 9,400 of the nearly 50000 ST of steel necessary 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 ft tall mockup of a section of the tower's wall with twenty-four windows was tested by Construction Consulting Laboratory West in Ontario, California. Testing also took place on another full-scale mockup south of Albuquerque, New Mexico. Both mockups passed the tests. In mid-April, a batch of concrete had to be replaced after it failed a stress test.

On May 17, 2008, the tower's steel breached street level when new sections were bolted to two of the twenty-four 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 roughly 90 percent of the construction contracts had been bid.

By August, 1 WTC had reached 25 ft above street level. During its September 16 meeting, the Port Authority board approved contracts for security and building management systems, and 95% of the contracts needed to complete the tower had been signed. On October 10, Collavino Construction poured an additional 520 cuyd of concrete for the tower's concrete core, raising it to just above street level.

By February 11, 2009, the tower was 105 ft above street level. On July 2, 2009, over 1200 cuyd of concrete were poured to form parts of the street-level plaza. On August 13, the builders of 1 WTC set a 70 ST piece of steel into place—the largest column installed yet at the building. Each steel column—made at a factory in Luxembourg—was about 60 ft long. The columns at the bottom of the tower's foundation were about 35 ft long.

By November 1, 2009, the twenty-four perimeter columns of 1 WTC had all been erected, and construction of the second floor (the first floor above ground level) was nearly complete. The Port Authority of New York and New Jersey reported in their 2009 Q3 annual report that steel construction would commence by January 2010, and that the typical floor construction was ready to begin.

2010–2011
Steel and concrete installation continued in 2010, where two cranes were on site. The fifth floor was finished on January 16. In February, construction began on the sixth floor, the last floor of 1 WTC's base, and the Port Authority announced that the tower's steel superstructure had reached 200 ft above street level. By the end of March 2010, steel beams were being erected for the second office floor. In April, the 45-degree octagon was installed, the building's steel frame had reached 26 floors, with concrete completed on the base structure in the latter part of the month.

In May 2010, the Port Authority stated that they were building nearly one floor per week, and it was projected that 1 WTC would reach 55 stories by the end of 2010. An advanced "cocoon" scaffolding system was installed to protect workers from falling, marking the first time that such a safety system had been installed on a steel structure in the city. On July 13, 2010, workers found the remains of an 18th-century sailing ship while excavating for the tower's underground vehicle security center.

By October 2010, the tower's steel superstructure had reached 44 stories, and by November, stainless steel and glass façade panels were being prepared for later installation, with the panels scheduled to be assembled between the 20th and 24th floors. Steven Coleman, spokesman for the Port Authority, stated, "Once they get rolling, they'll be able to install glass panels at a rate of one floor per week." By mid-November, the tower's steel had reached 48 stories.

On December 16, 2010, the Port Authority announced that the tower's construction had reached the 52nd floor, rising to over 600 ft and marking the halfway point for the tower's steel frame. By February 2011, the tower had reached the 56th floor, 667 ft above grade, with glass panels reaching the 27th floor. On May 12, 2011, plans to install prismatic glass on the tower's base were cancelled due to technical problems. By June 2011, the tower had reached the 70th floor, with glass paneling and concrete flooring reaching the 45th and 63rd floors, respectively. On September 11, 2011, ten years after the destruction of the original World Trade Center, the tower's steel reached the 82nd floor, while its concrete reached the 72nd floor and glass cladding reached the 56th floor. By September 30, 2011, the tower's steel had reached the 84th floor, rising 1040 ft above street level, with glass paneling at the 59th floor and concrete flooring reaching the 76th floor. By this point, the incomplete tower was clearly visible on the skyline, rising above surrounding towers. By the end of October 2011, the tower had become the third-tallest building in New York City, surpassing the Chrysler Building and the New York Times Building.

While under construction in late 2011, the tower was specially illuminated on two key occasions. On September 10, it was lit up in the colors of the American flag to commemorate the 10th anniversary of the September 11 terrorist attacks, and on October 27, it was illuminated in pink in honor of Breast Cancer Awareness Month. By November 21, 2011, the tower's steel had reached the 90th floor, rising approximately 1120 ft above street level.

As of December 7, 2011, the tower's steel has risen to the 92nd floor (1,146 ft), while glass panels have reached the 65th floor and concrete flooring has risen to the 83rd floor.

Estimated completion and cost
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 in connection with the September 11 attacks was used for construction of the new tower. The State of New York provided $250 million toward construction costs, and the Port Authority agreed to finance another $1 billion through bonds.

One WTC was originally expected to be completed and opened by 2011, but an October 2008 report by the PANYNJ pushed back the estimated completion of the tower to the second  quarter of 2012, with the total budget being estimated at $3.1 billion – a slight increase over the 2007 estimate. In January 2011, Lynda Tollner of the Port Authority predicted that work on the tower's steel structure would be finished by early 2012. In July 2011, the Port Authority estimated that One World Trade Center would be completed and opened by the end of April 2013.

Design issues
The design of 1 WTC generated controversy for several reasons. Firstly, criticism was levelled at the limited number of floors in an early design that were designated for office space and other amenities. Under this design, only 82 floors would have been habitable, and the overall office space of the entire rebuilt World Trade Center would have been reduced by more than 3000000 sqft in comparison with the original complex. The floor limit was imposed by Silverstein, who expressed concern that higher floors would be a liability in another major accident or terrorist attack. In a subsequent design, the highest space that could be occupied became comparable to the original World Trade Center.

Other criticisms were aimed at the appearance of the building. An unofficial movement to rebuild the lost towers instead of building a single tower, called the Twin Towers Alliance, collected more than eight thousand signatures supporting the rebuilding of the Twin Towers. Allegations furthermore emerged that, in its Final Generic Environmental Impact Statement (FGEIS), the LMDC had proposed a "Restoration Alternative", which would have restored the World Trade Center site substantially as it existed before September 11, 2001, with updated technology. In May 2005, Developer Donald Trump proposed a twin building design called World Trade Center Phoenix (Twin Towers II). The twin design would look similar to the original twin towers, but the buildings would be considerably taller, featuring improved safety measures and much larger windows.

A key feature of the final tower design – the fortified, windowless base – was also a source of controversy. A number of critics (notably Deroy Murdock of the National Review) suggested that the reinforced base was alienating and dull, reflecting a sense of fear rather than freedom, leading them to dub the project "the Fear Tower".

Other controversies
During the tower's planning stages, 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 his friend and campaign contributor, Ron Lauder.

In May 2011, detailed floor plans of the tower were displayed on New York City's Department of Finance website, resulting in an uproar from the media and citizens of the surrounding area, who warned that the plans could potentially be used for a future terrorist attack.

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 has full control of the tower itself. Silverstein signed a 99-year lease for the World Trade Center site in July 2001. Silverstein has pledged to support the reconstruction and remains actively involved in most aspects of the redevelopment process.



David Childs
David Childs, one of Silverstein's favorite architects, initially joined the project at the urging of Silverstein and developed a proposal for 1 WTC in collaboration with Daniel Libeskind. The design was revised in May 2005 to address security concerns. He is the project architect of the tower, and is responsible for overseeing the day-to-day design development from rough inception to final completion.

Daniel Libeskind
Architect 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. Libeskind later 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 with, and resemble, the Statue of Liberty. Although these designs were later scrapped, he continued to contribute to the design and development of the World Trade Center site.

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.

Douglas and Jody Durst
Douglas and Jody Durst, the co-presidents of the Durst Organization, a real estate development company, won the right to invest at least $100 million in the project on July 7, 2010. The Durst Organisation is a family-owned company that specializes in the development, managing, leasing, and operation of sustainable commercial construction space. Condé Nast, a long-time Durst tenant, also confirmed a tentative deal to move into 1 World Trade Center in August 2010, and finalized the deal on May 26, 2011.

Port Authority construction workers
A WoodSearch Films short-subject documentary was uploaded to YouTube on August 31, 2010, entitled How does it feel to work on One World Trade Center?. Nearly all of the construction workers interviewed praised the unity and work ethic of the new World Trade Center's construction team. Others spoke of the importance they believed the construction of the tower had to the people of the United States. A deputy foreman, George Collins, said, "All the men are working in conjunction to put this building up. They all know how important this is to the country – and to show the world what us Americans can do – and get this done, union and proud." Another deputy foreman, Scott Williams, commented, "[The] camaraderie of the crew is very good."