Construction of One World Trade Center

Construction of One World Trade Center

Construction of One World Trade Center was deferred until 2006 because of disputes between port authority and the developer. Tishman Realty & Construction,[1] is the selected builder. The building reached ground level on May 17, 2008 and is scheduled to be completed by the end of 2012 and will open in January 2013.



The symbolic cornerstone of One World Trade Center was laid down in a ceremony on July 4, 2004,[2] but further construction of the tower was stalled until 2006. The cornerstone was temporarily removed from the site on June 23, 2006.[3] The project was 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, explosives were detonated at the World Trade Center construction site, testing the use of charges to clear bedrock for the building's foundation. Controlled explosions continued for approximately two months thereafter.

One World Trade Center tower construction as of August 7, 2007.

On November 18, 2006, 400 cubic yards (310 cubic metres) 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 a30-foot (9.1 m) steel beam.[4] This beam, the first to be installed, was welded on to the building's base on December 19, 2006.[5]

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).[6] Approximately $1 billion of insurance money recouped by Silverstein in connection with the September 11 attacks is being used for construction of the new One World Trade Center.[6] The State of New York is expected to provide $250 million toward construction costs, and the Port Authority agreed to finance another $1 billion through bonds.[7] 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.[8]


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.[8] By February 22, 2008, 9,400 of the nearly 50,000 short tons (45,000 t) of steel necessary had been ordered.[9] By March 13, 2008, the steel for the tower had reached 70 feet (21 m) high, 10 feet (3 m) below street level.[10][11] From late March through early April, a 40-foot (12 m) tall mockup of a section of the tower's wall with twenty-four windows was tested by Construction Consulting Laboratory West in Ontario, California. The purpose of the testing was to ensure that the all-glass exterior of the tower will be able to withstand earthquakes and extreme weather conditions.[12] Testing also took place on another full-scale mockup south of Albuquerque, New Mexico. Both mockups passed the tests.[13] In mid-April, a batch of concrete had to be replaced after it failed a stress test.[14]

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 feet (4.6 m) above street level.[15] In June, the chamfered steel skeleton of the tower's concrete base had begun to take shape.[16] By the end of the month, the concrete had been poured for the floor of the tower's basement level B3.[17] 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.[18]

One World Trade Center Site on July 12, 2009.

By August, 1 WTC had reached 25 feet (7.6 m) above street level.[19] During its September 16 meeting, the Port Authority board approved contracts for security and building management systems,[20] and 95% of the contracts needed to complete the tower had been signed.[21] The $20 million security contract includes sophisticated video analysis in which computers would alert security personnel to abnormal situations automatically.[22] On October 10, Collavino Construction poured an additional 520 cubic yards (400 m3) of concrete for the tower's concrete core, raising it to just above street level.[23]

By February 11, 2009, the tower was 105 feet (32 m) above street level.[24] On July 2, 2009, over1,200 cubic yards (920 m3) of concrete were poured to form parts of the street-level plaza. On August 13, the builders of 1 WTC set a70 short tons (64,000 kilograms) 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 feet (18 m) long. The columns at the bottom of the tower's foundation were about 35 feet (11 m)long.[25]

By November 1, 2009, the twenty-four perimeter columns of 1 WTC were all erected, and construction of the second floor (the first floor above ground level) was nearly complete. In addition, The Port Authority of New York and New Jersey reported in their 2009 Q3 Annual Report that steel erection should commence by January 2010, and that the typical floor construction could begin.[26]


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 feet (61 m) above street level.[27] By the end of March 2010, steel beams began to be erected for the second office floor. In April, the 45-degree octagon was installed, the building's steel frame had reached 26 floors, and concrete was completed on the base structure in the latter part of the month.[28]

In May 2010, the Port Authority stated that they were building close to one floor per week, and was projected that One World Trade Center would reach 55 stories by the end of 2010.[29] The cocoon system was also installed, marking the first time a cocoon safety system has been installed on a steel superstructure in the city.[30]

On July 13, 2010, workers found remains of an 18th century sailing ship at the World Trade Center site while excavating for the underground vehicle security center for One World Trade Center.[31] The remains of a 32-foot (9.8 m) section of the ship's hull and a 100-pound (45 kg) anchor were found. The hull had been truncated and the beams sawed.[32] The ship was likely used as landfill material during the early 19th century to help expand Manhattan. Timbers from the ship were removed and sent to a laboratory to try to date the vessel.[33] An additional section of the ship was found on the site in August 2011, giving historians more information about the vessel, which was active around the 1770s.[34]

By October 2010, the tower's steel superstructure reached 44 stories.[35][36] In November, stainless steel and glass facade panels were being prepared for later installation, with the panels scheduled to be assembled between the 20th and 24th floors.[37] On November 13, the first glass facade panels were installed on the 20th floor. 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."[38] By November 17, the tower's steel had reached 48 stories.[39]

The Port Authority announced on December 16, 2010 that 1 WTC had reached the 52nd floor, and had risen to over 600 feet (180 m), marking the halfway point for the construction of the building's steel frame.[40][41] By February 2011, the tower reached 56 floors,667 feet (203 m) above grade, while the glass panels reached the 27th floor.[42] On May 12, 2011, plans were cancelled to install prismatic glass on the building's base due to technical problems.[43]

By June 15, 2011, One World Trade Center had reached the 70th floor, the glass facade installation had reached the 45th floor, and concrete flooring had been installed up to the 63rd.[44] On August 1, 2011, concrete workers and carpenters at the tower walked off the job one month after their labor contract had expired; the workers returned to work on August 3.[45][46]

As of November 21st, 2011, One World Trade Center's steel structure reached the 90th floor, concrete reached the 81st floor, and its glass has reached the 64th floor. [47]

Estimated completion and cost

One WTC was originally expected to be completed and opened by 2011,[48][49] 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 estimated budget growing slightly from the 2007 estimate to $3.1 billion.[50] As of July 2011, the building remains scheduled to be completed by the end of 2013, according to the Port Authority.[51]



  1. ^ "WTC builder on the project's status | The Real Deal | New York Real Estate News". The Real Deal. 2010-02-01. Retrieved 2011-11-17. 
  2. ^ "Governor Pataki, Governor McGreevey, Mayor Bloomberg Lay Cornerstone for Freedom Tower" (Press release). Office of the Governor of New York State. July 4, 2004. [dead link]
  3. ^ "Cornerstone of Freedom Tower removed". CBS News. June 25, 2006. Archived from the original on January 8, 2007. 
  4. ^ Chan, Sewell (December 18, 2006). "Messages of Love and Hope on a Freedom Tower Beam". The New York Times. 
  5. ^ "First Freedom Tower Beam Rises At Ground Zero". WCBS-TVV. December 19, 2006. Archived from the original on December 20, 2006. 
  6. ^ a b Nordenson, Guy (February 16, 2007). "Freedom From Fear". The New York Times. 
  7. ^ Bagli, Charles V. (February 13, 2007). "Spitzer, in Reversal, Is Expected to Approve Freedom Tower, Officials Say". The New York Times. 
  8. ^ a b "Statement by Port Authority Regarding Preparation of Towers 3 and 4 Bathtub at WTC Site to Allow Silverstein Properties to Begin Construction in January" (Press release). Port Authority of New York & New Jersey. December 31, 2007. 
  9. ^ Westfeldt, Amy (February 22, 2008). "Long Journey of Freedom Tower Steel". Associated Press. [dead link]
  10. ^ Ritter, Ian (March 13, 2008). "Silverstein: WTC Still on Track for 2012 Finish". 
  11. ^ "Rising from the Pit". March 17, 2008. 
  12. ^ Topousis, Tom (April 1, 2008). "'FREEDOM' RATTLED". New York Post. 
  13. ^ Dunlap, David W. (April 9, 2008). "Replicas of New Tower Endure Nature’s Fury and a Test Blast". New York Times. 
  14. ^ "Weak Concrete Foundation Removed From Freedom Tower". NY1. April 16, 2008. Retrieved April 19, 2008. 
  15. ^ Dunlap, David W. (May 19, 2008). "Not Yet on the Skyline, but Above Street Level". New York Times. 
  16. ^ Dunlap, David W. (June 19, 2008). "Chamfer, Anyone? Cutting Corners on a Large Scale". New York Times. Retrieved July 13, 2008. 
  17. ^ Dunlap, David W. (July 3, 2008). "The Choreography (Quickly!) of Concrete". New York Times. Retrieved July 13, 2008. 
  18. ^ Ward, Chris (2008) (PDF). World Trade Center Site Update (Report). Port Authority of New York and New Jersey. pp. 13. Retrieved June 30, 2008. 
  19. ^ Frazier, Michael (August 17, 2008). "Construction progress slow at World Trade Center site". Newsday (Melville, New York: Newsday Inc.).,0,4404790.story. [dead link]
  20. ^ "Port Authority Board Takes Action on Several items" (Press release). Port Authority of New York & New Jersey. September 16, 2008. 
  21. ^ Hennelly, Bob (September 16, 2008). "Port Authority Approves Freedom Tower Contracts". WNYC. Retrieved September 18, 2008. 
  22. ^ Dunlap, David W. (September 24, 2008). "Unblinking Eyes, for $20 million, at Freedom Tower". New York Times. Retrieved September 24, 2008. 
  23. ^ Dunlap, David W. (October 20, 2008). "Phantom Freedom Tower Visible to All". New York Times. Retrieved October 21, 2008. 
  24. ^ "Image Gallery". Port Authority of New York and New Jersey. February 11, 2009. Retrieved February 21, 2009. [dead link]
  25. ^ 6:10 pm ET (August 12, 2009). "Huge column is largest installed at WTC tower - Life". MSNBC. Retrieved March 13, 2010. 
  26. ^ "World Trade Center Quarterly Report 3rd Quarter 2009 –" (PDF). Retrieved 2011-11-17. 
  27. ^ World Trade Center (Freedom Tower) Lower'.' Retrieved 2010-2-4.
  28. ^ 1 World Trade Center reaches 20th-floor levelSITimes'.' Retrieved March 20, 2010.
  29. ^ World Trade Center project has begun to take shape New Jersey On-line'.' Retrieved May 12, 2010.
  30. ^ Port Authority installs cocoon safety system around World Trade Center steel structure, May 2010
  31. ^ 18th-Century Ship Found at Trade Center Site. The New York Times. Retrieved July 15, 2010
  32. ^ Ship Buried in 18th Century Unearthed at WTC SiteFox News Retrieved July 15, 2010
  33. ^ Buried ship found at World Trade Center site. Los Angeles Times Retrieved July 15, 2010
  34. ^ "Second piece of 18th-century ship unearthed at World Trade Centre site offers clues it transported British troops to the New World". The Daily Mail, August 7, 2011
  35. ^ "Port Authority Board Approves Agreement that Will Fully Restore WTC Site". 2011-09-19. Retrieved 2011-11-17. 
  36. ^ World Trade Center tower reaches 44 stories high and curtain wall installation this month Rochester Democrat and Chronicle Retrieved October 29, 2010
  37. ^ One World Trade Center Prepared to Shine Digital Network Associates Info Retrieved November 17, 2010
  38. ^ "World Trade Center Tower Begins to Show Its Shimmering Face || News || World Trade Center ||". 2011-09-19. Retrieved 2011-11-17. 
  39. ^ "World Trade Center Tower Begins to Show Its Shimmering Face". The Tribeca Trib. Retrieved 2011-11-17. 
  40. ^ a b "1 WTC, aka Freedom Tower, reaches halfway mark", The Wall Street Journal/Associated Press, December 16, 2010
  41. ^ "Freedom Tower half complete" New Zealand Herald Retrieved December 17, 2010
  42. ^ "Construction Progress Around the WTC Site". World Trade Center Progress newsletter, February 2011,, accessed May 12, 2011
  43. ^ "Prismatic glass facade for WTC tower scrapped". Huffington Post, May 12, 2011. Retrieved June 19, 2011.
  44. ^ World Trade Center Growing This Summer. "World Trade Center Growing This Summer" Retrieved June 1, 2011
  45. ^ "Concrete Workers End Strike at WTC Site". NY1 News and Time Warner Cable Inc., August 4, 2011
  46. ^ Joseloff, Matt and Stephen Nessen."World Trade Center Workers Walk Off Job for Second Day". WNYC News Blog, New York Public Radio, August 2, 2011
  47. ^ "Lower Manhattan : 1 World Trade Center". Retrieved 2011-11-17. 
  48. ^ Two columns installed at Ground Zero site Seattle Times Retrieved November 17, 2010
  49. ^ Trade Site to Have 3 of City's Tallest Towers Bloomberg News Retrieved November 17, 2010
  50. ^ Ward, Chris (2008) (PDF). World Trade Center Report: A Roadmap Forward (Report). Port Authority of New York and New Jersey. pp. 26. Retrieved October 2, 2008. 
  51. ^ "1 World Trade Center (Freedom Tower)", accessed May 12, 2011

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