Construction of One World Trade Center facts for kids
The construction of New York City's One World Trade Center started later than planned, in 2006. This was because of disagreements between the Port Authority of New York and New Jersey and the company in charge. Tishman Realty & Construction was chosen to build it. The building reached ground level on May 17, 2008, and its highest point on May 10, 2013. One World Trade Center welcomed its first businesses on November 3, 2014. The One World Observatory, a viewing deck, opened to visitors on May 28, 2015.
Contents
Building Begins: 2004–2007
One World Trade Center was one of the first big buildings planned using a special 3D computer model. A symbolic first stone was placed on July 4, 2004. However, actual building work stopped until 2006 due to disagreements about money, safety, and the building's design. These issues were finally solved on April 26, 2006, with a deal between developer Larry Silverstein and the Port Authority of New York and New Jersey.
In the summer of 2006, small explosions were used at the site. This helped clear away bedrock for the building's deep foundation. These controlled blasts continued for about two months.
On November 18, 2006, a large amount of concrete, about 400 cubic yards, was poured for the foundation. This concrete was brought by 40 trucks. On December 17, 2006, people were invited to sign a 30-foot steel beam in Battery Park City. This special beam was the first to be put in place, welded to the building's base on December 19, 2006.
By January 9, 2007, more beams were added. In February 2007, the cost to build One World Trade Center was estimated at $3 billion. About $1 billion came from insurance money that Silverstein received after the September 11 attacks. The State of New York also provided $250 million, and the Port Authority helped with another $1 billion through special loans. By the end of 2007, the building's footings and foundations were almost finished.
Rising Up: 2008
In January 2008, two large construction cranes arrived at the site. The building's concrete core, which is like its spine, started to rise. By February 22, 2008, a lot of the necessary steel had been ordered. By March 13, 2008, the steel for the tower was 70 feet high, still below street level.
In March and April, a 40-foot model of a part of the tower's wall was tested in California. This test made sure the building's all-glass outside could handle earthquakes and bad weather. Another test happened in New Mexico, and both models passed. In mid-April, some concrete had to be replaced because it wasn't strong enough.
On May 17, 2008, the tower's steel finally reached street level. New sections were bolted to the large steel columns that marked the building's shape. By June, the concrete had been poured for one of the basement floors. By August, the building was 25 feet above street level.
In September, the Port Authority approved contracts for security systems. These included smart cameras that could spot unusual things automatically. On October 10, more concrete was poured for the tower's core, bringing it just above street level.
Growing Taller: 2009
By February 11, 2009, the tower was 105 feet above street level. On July 2, 2009, a lot of concrete was poured to create parts of the street-level plaza. On August 13, builders put a 70-ton piece of steel into place. This was the largest column installed so far. Each steel column was about 60 feet long and made in Luxembourg.
By November 1, 2009, all 24 outer columns of One World Trade Center were standing. The construction of the second floor, the first floor above ground, was almost done. The Port Authority expected that steel would start going up quickly by January 2010.
Reaching Higher: 2010
Steel and concrete work continued in 2010 with two cranes on site. The fifth floor was finished on January 16. In February, work began on the sixth floor, which was the last floor of the building's base. The Port Authority announced that the tower's steel frame had reached 200 feet above street level. By the end of March 2010, steel beams were being put up for the office floors. In April, the building's steel frame reached 26 floors.
In May 2010, the Port Authority said they were building almost one floor per week. They thought One World Trade Center would reach 55 stories by the end of 2010. A special safety system, called a cocoon system, was also installed. This was the first time such a system was used on a steel building in New York City.
On July 13, 2010, workers found parts of an 18th-century sailing ship while digging for the underground Vehicle Security Center. They found a 32-foot section of the ship's hull and a 100-pound anchor. The ship was likely used as landfill material in the early 1800s to expand Manhattan. The ship's wood was sent to a lab to find out its age. More of the ship was found in August 2011, giving historians more clues about the vessel, which was active around the 1770s.
By October 2010, the tower's steel frame reached 44 stories. In November, glass panels for the outside of the building were being prepared. The first glass panels were installed on the 20th floor on November 13. A spokesperson for the Port Authority said that once they got started, they could install glass panels at a rate of one floor per week. By November 17, the tower's steel reached 48 stories.
On December 16, 2010, the Port Authority announced that One World Trade Center had reached the 52nd floor. It was over 600 feet tall, marking the halfway point for the building's steel frame.
Almost There: 2011
By February 2011, the tower reached 56 floors, standing 667 feet tall. The glass panels reached the 27th floor. On May 12, 2011, plans to use special glass on the building's base were canceled due to technical problems.
By June 15, 2011, One World Trade Center reached the 70th floor. The glass outside reached the 45th floor, and concrete floors were installed up to the 63rd. On August 1, 2011, concrete workers and carpenters stopped working for a short time after their work agreement ended. They returned to work on August 3.
Topping Out: 2012
Building slowed down from January to February 2012. This was due to bad weather with strong winds and ice, which made it unsafe for workers. There were also delays because of problems with the company that supplied steel beams. It took over two months to finish the 92nd floor. As the weather improved and financial issues were solved, construction moved past the 92nd floor. One World Trade Center soon became the third tallest building in New York City.
On June 21, 2012, One World Trade Center reached its full roof height. Construction slowed again from late June to mid-July due to high temperatures, which delayed putting up the antenna spire. By July 16, workers began installing parapet steel at the top of the building. On July 18, the first "node steel" was installed. By July 31, 2012, all corner parapet columns were in place. A special beam, signed by U.S. President Barack Obama, local officials, and the construction workers, was raised on August 2, 2012.
By August 10, 2012, concrete flooring was completed up to the 93rd story. One World Trade Center had risen to the 105th floor, and glass was installed up to the 82nd floor. The building was structurally finished on August 30, 2012, when the last of the connecting beams were installed.
In late 2012, workers put up a temporary steel frame at the top of the tower. This frame would support the 408-foot steel spire during its assembly. The spire was made in 16 separate parts in Canada and brought by boat to New York City in mid-November. After Thanksgiving, crews began moving the spire sections one by one to the site. Once there, the spire parts were put together, piece by piece, at the very top of One World Trade Center.
On December 12, 2012, the first of nine large pieces of the spire were lifted to the 104th floor. Nine smaller pieces were also brought from Montreal.
Completion and Opening: 2013–2015
On May 10, 2013, the last two sections of the building's spire were installed. This made One World Trade Center the tallest building in the Western Hemisphere and the third tallest in the world.
The temporary outside elevator was removed between January and June 2014. The covering for the building's base began in February 2013 and finished in June 2014. Work started on the plaza around the building in late 2013, and the inside work was finished in November 2014.
The building officially opened on November 3, 2014, to 175 employees of the publisher Condé Nast.
On May 29, 2015, the One World Observatory, located at the top of the tower, opened to the public.
Images for kids
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Concrete construction, as of October 7, 2006
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Steel installation, as of March 26, 2007
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Foundation construction, as of October 7, 2007
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Construction progress, as of January 21, 2008
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Concrete foundation, as of April 20, 2008
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Construction progress, as of September 10, 2008
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One WTC above street level, as of February 28, 2009.
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One WTC viewed from street level on July 29, 2009.
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The final lobby column being installed on October 31, 2009.
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Construction reaching the 17th floor, as of December 10, 2009.
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View from the World Financial Center, March 8, 2010.
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Construction progress, as of April 2010.
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View from Church Street, May 11, 2010, as steel tops the 24th floor.
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View from the PATH station entrance, June 10, 2010, as steel tops the 26th floor.
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Construction work as of July 28, 2010, as steel reached the 30th floor.
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Construction as of September 28, 2010, as steel reached the 42nd floor.
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One World Trade Center on November 10, 2010, reaching the 48th floor.
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December 19, 2010, after steel reached the 52nd floor; the halfway point.
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As of January 13, 2011, with the glass facade clearly visible.
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View from West Street as of February 5, 2011. 7 World Trade Center is visible in the background on the right. Steel tops the 56th floor.
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March 19, 2011, as construction reaches the 60th floor.
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Progress as of May 2, 2011, Steel is up to the 64th floor and glass is at the 36th floor.
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June 1, 2011.
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August 16, 2011.
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Progress as of September 17, 2011. Steel is at 83 floors, glass at 58 floors and concrete at the 72nd floor.
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Progress as of October 13, 2011. Steel is at 86 floors, glass is at 60 floors and concrete is at 76 floors.
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Progress as of November 15, 2011. Steel is past 89 floors, glass is at the 63rd floor, and concrete is past the 80th floor.
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Progress as of December 23, 2011, pictured from the corner of Liberty and Greenwich Street. Steel is up to 92 floors, glass is up to 68 floors, and concrete is up to 84 floors.
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One World Trade Center on January 28, 2012.
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One World Trade Center on March 13, 2012.
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One World Trade Center on April 13, 2012. Steel is up to 100 floors, and glass is at 71.
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One World Trade Center as of May 27, 2012.
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One World Trade Center under construction on July 24, 2012.
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One World Trade Center on August 20, 2012.
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One World Trade Center on November 4, 2012.
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One World Trade Center on February 22, 2013. The first two sections of the spire now in place.
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One World Trade Center on May 1, 2013. Windows now reaching the top of the building.
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The spire beacon was installed on May 10, 2013, as seen here
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One WTC as of June 1, 2013
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One WTC as of January 22, 2014
