Construction of One World Trade Center
| Company type | Commercial skyscraper |
|---|---|
| Industry | Construction, Real estate |
| Founded | 2006 |
| Headquarters | New York City , United States |
Key people | Larry Silverstein (developer), Christopher O. Ward (Port Authority executive director) |
| Products | Office space, observatory, commercial real estate |
Number of employees | 175 (Condé Nast initial tenant staff) |
| Parent | Port Authority of New York and New Jersey (developer oversight) |
One World Trade Center serves as the flagship structure within the reconstructed World Trade Center complex located in Lower Manhattan, New York City. Construction commencement was postponed until 2006 due to disagreements between the Port Authority of New York and New Jersey and developer Larry Silverstein. The project’s construction was entrusted to Tishman Realty & Construction. The building reached ground level on May 17, 2008, achieved its full height on May 10, 2013, welcomed tenants starting November 3, 2014, and opened its observatory to visitors on May 29, 2015.
2004–2007
One World Trade Center is distinguished as the inaugural major structure built utilizing a three-dimensional Building Information Model. Its symbolic cornerstone was placed on July 4, 2004; however, progress was halted until 2006 due to financial, security-related, and design conflicts. The cornerstone was temporarily removed on June 23, 2006. Following an agreement reached between Silverstein and the Port Authority on April 26, 2006, construction activities resumed. Controlled demolition techniques were employed in summer 2006 to prepare the bedrock for the foundation.
On November 18, 2006, approximately of concrete was poured to establish the foundation. A public signing event took place on December 17, where individuals inscribed their names on a steel beam that was subsequently welded into place on December 19. By January 9, 2007, additional steel beams had been installed atop the initial framework.
By February 2007, estimated construction expenses were projected at $3 billion ($1,150 per square foot). Around $1 billion from September 11 insurance settlements was designated for building costs. The State of New York pledged $250 million, while the Port Authority committed $1 billion in bond financing. During 2007, Tishman Construction completed the installation of perimeter steel columns and erected two tower crane bases equipped with luffing-jib cranes. By the end of the year, footings and foundations were nearly finished.
2008
In January 2008, two cranes were delivered to the site as work began on raising the tower’s concrete core. By February 22, orders had been placed for approximately 9,400 tons of steel out of the nearly required for completion. By March, steel erection had reached a height of , which is below street level. From late March through early April, a full-scale mockup standing tall of the tower’s all-glass façade underwent testing in Ontario, California and near Albuquerque, New Mexico to verify its ability to withstand seismic activity and severe weather conditions; both tests were successful. In mid-April, a batch of concrete was rejected following failure in stress evaluations.
On May 17, steel framing reached street level as new segments were bolted onto jumbo steel columns, elevating the structure above ground. By June, the chamfered steel framework forming the concrete base began taking shape, with concrete poured for basement level B3 by month’s end. Port Authority executive director Christopher O. Ward announced that roughly 90% of construction contracts had been awarded by June 30.
By August, One World Trade Center (1 WTC) had risen above street level. On September 16, contracts for security and building management systems were approved by the Port Authority board; at this point, 95% of essential contracts had been finalized. The $20 million security contract incorporated advanced video analytics for automated alerting. On October 10, Collavino Construction poured an additional of concrete into the tower’s core structure, raising it just above street level.
2009
By February 11, 2009, the structure had ascended to 105 feet above the street. On July 2, more than 1,200 cubic yards of concrete were poured to form the plaza at street level. On August 13, construction teams installed a steel column weighing 70 tons—the largest so far—each approximately 60 feet in length, with foundation columns measuring around 35 feet.
By November 1, all twenty-four perimeter columns had been set in place, and the second floor was nearly finalized. The Port Authority's third-quarter report for 2009 anticipated that steel erection would commence by January 2010, followed by standard floor construction.
2010
Work on steel and concrete continued with two cranes operating on site. By January 16, the fifth floor was completed. Construction of the sixth floor and the base’s top began in February, with the steel superstructure reaching 200 feet above ground level. By March, steel beams were being installed for the second office floor. In April, the steel framework extended up to 26 floors, and concrete work on the base was finished.
In May, the Port Authority reported that progress was nearly one floor per week, forecasting a total of 55 stories by year-end. The cocoon safety system—a first for a steel superstructure in the city—was installed.
During July, excavation for the underground Vehicle Security Center revealed remnants of an 18th-century sailing vessel. The hull and anchor indicated it had been used as landfill during early Manhattan development. Further sections discovered in August 2011 offered additional historical context.
By October, the steel frame had reached 44 floors. Preparations began for installing stainless steel and glass facade panels between floors 20 and 24. The initial glass panels were set on November 13 at the 20th floor; installation was expected to proceed at a rate of one floor per week. By mid-November, steel construction had reached 48 stories.
On December 16, the Port Authority announced that One World Trade Center had climbed to the 52nd floor and exceeded a height of 600 feet—signifying that half of the steel frame construction was complete.
2011
By February 2011, the tower stood at 56 floors and reached 667 feet above grade, with glass panels installed up to the 27th floor. Plans to use prismatic glass at the base were abandoned in May due to technical challenges. By June 15, One World Trade Center had risen to its 70th floor; glass facade installation extended to the 45th floor, and concrete flooring was finished through the 63rd floor. A brief labor strike occurred in August but lasted only two days before workers returned.
2012
Early in 2012, construction progress slowed because warm winter conditions caused dangerous icing hazards and financial delays from a steel supplier resulted in over two months needed to complete work on the 92nd floor. Once these issues were resolved, construction advanced beyond the 92nd floor. One World Trade Center surpassed the Bank of America Tower as New York City's third tallest building during this period. In May, plans to remove the radome from the spire were announced but later retracted in 2013. On November 12, 2013, the building was officially recognized as the tallest structure in the Northeastern United States, ranked eleventh tallest worldwide, and holder of the tallest spire globally.
On June 21, 2012, One World Trade Center topped out at roof level, placing it roughly thirtieth among skyscrapers worldwide. Construction halted from late June until mid-July due to extreme heat delaying antenna spire installation. Work resumed with parapet steel installation starting mid-July; by July 31 all corner parapet columns—referred to as "node steel"—were installed. A ceremonial beam signed by President Obama and others was hoisted on August 2 during an event not officially termed a topping-out ceremony. By August 10, concrete flooring reached the 93rd level; the tower rose to its 105th floor; and glass installation extended up to the 82nd floor. The steel framework was completed on August 30.
Toward late 2012, a temporary steel structure was erected atop the tower to support assembly of the 408-foot spire. Manufactured in sixteen sections near Montreal, these segments were transported by barge to New York City in mid-November. Starting just after Thanksgiving, crews assembled spire components piece by piece atop One World Trade Center. On December 12, nine initial spire segments were lifted to the 104th floor; additional smaller pieces arrived from Montreal thereafter.
2013–2015
On May 10, 2013, the installation of the final two segments of the spire was completed, establishing the building as the tallest structure in the Western Hemisphere and ranking it third globally.
The process of removing the exterior elevators commenced in late January 2014 and was finalized by early June of the same year. Work on the base cladding began in February 2013 and reached completion by June 2014. Construction of the plaza started toward the end of 2013, while interior finishing touches were completed by November 2014.
The tower officially opened its doors on November 3, 2014, with its inaugural tenant being the publishing company Condé Nast, which occupied space for 175 staff members.
On May 29, 2015, the One World Observatory located at the top of the tower was made accessible to visitors, further solidifying its role as a prominent commercial hub and tourist attraction.
External links
- Port Authority Live Camera tracking construction developments