page_title: Construction of One World Trade Center
section_title: 2008
hierarchical_section_title: Construction of One World Trade Center / 2008
caption_attribution_description: English: Ground Zero Site in New York, New York, in July 2009
context_page_description: Construction of One World Trade Center was deferred until 2006 because of disputes between the Port Authority of New York and New Jersey and the developer. Tishman Realty & Construction is the selected builder. The building reached ground level on May 17, 2008, and was topped out on May 10, 2013. One World Trade Center opened to tenants on November 3, 2014, and One World Observatory opened to the public on May 28, 2015.
context_section_description: 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 50,000 short tons (45,000 t) of steel necessary had been ordered. By March 13, 2008, the steel for the tower had reached 70 feet (21 m) high, 10 feet (3 m) 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 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. 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 reached 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. 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 feet (7.6 m) 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. The $20 million security contract includes sophisticated video analysis in which computers would alert security personnel to abnormal situations automatically. 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.
caption: One World Trade Center Site on July 12, 2009.
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