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7 World Trade Center (1987–2001)

Coordinates: 40°42′48″N 74°00′43″W / 40.7133°N 74.0119°W / 40.7133; -74.0119
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This article is about the original building destroyed on September 11, 2001. For the new structure on the site completed in 2006, see 7 World Trade Center.

7 World Trade Center
The original 7 World Trade Center from the WTC observation deck. August 1992
Map
Alternative names
  • WTC 7
  • 7 WTC
  • Building 7
  • Tower 7
  • Salomon Brothers Building
General information
StatusDestroyed
TypeOffice
Location250 Greenwich Street
Manhattan, New York 10006, United States
Coordinates40°42′48″N 74°00′43″W / 40.7133°N 74.0119°W / 40.7133; -74.0119
Construction startedOctober 2, 1984
CompletedMarch 1987
OpenedMay 1987
DestroyedSeptember 11, 2001
Height
Architectural610 ft (190 m)
Technical details
Floor count47
Floor area2,000,000 sq ft (190,000 m2)
Lifts/elevators32
Design and construction
Architect(s)Emery Roth & Sons
DeveloperSilverstein Properties
Structural engineerIrwin Cantor
Main contractorTishman Construction
World Trade Center
Towers
Other elements
Artwork
History

7 World Trade Center (7 WTC, WTC-7, or Tower 7), colloquially known as Building 7 or the Salomon Brothers Building, was an office building constructed as part of the original World Trade Center Complex in Lower Manhattan, New York City. The tower was located on a city block bounded by West Broadway, Vesey Street, Washington Street, and Barclay Street on the east, south, west, and north, respectively. It was developed by Larry Silverstein, who held a ground lease for the site from the Port Authority of New York and New Jersey, and designed by Emery Roth & Sons. It was destroyed during the September 11 attacks.

The original 7 World Trade Center was 47 stories tall, clad in red granite masonry, and occupied a trapezoidal footprint. An elevated walkway spanning Vesey Street connected the building to the World Trade Center plaza. The building was situated above a Consolidated Edison power substation, which imposed unique structural design constraints. When the building opened in 1987, Silverstein had difficulties attracting tenants. Salomon Brothers signed a long-term lease in 1988 and became the anchor tenant of 7 WTC.

On September 11, 2001, the structure was substantially damaged by debris when the nearby North Tower (1 World Trade Center) collapsed. The debris ignited fires on multiple lower floors of the building, which continued to burn uncontrolled throughout the afternoon. The building's internal fire suppression system lacked water pressure to fight the fires. It began to collapse when a critical internal column buckled and triggered cascading failure of nearby columns throughout, which were first visible from the exterior with the crumbling of a rooftop penthouse structure at 5:20:33 pm. This initiated the progressive collapse of the entire building at 5:21:10 pm, according to FEMA,[1]: 23  while the 2008 NIST study placed the final collapse time at 5:20:52 pm.[2]: 19, 21, 50–51  The collapse made the old 7 World Trade Center the first steel skyscraper known to have collapsed primarily due to uncontrolled fires.[3][4] A new building on the site opened in 2006.

Architecture

Transfer trusses used on the 5–7th floors to redistribute load to the foundation

The original 7 World Trade Center was a 47-story building, designed by Emery Roth & Sons, with a red granite facade. The building was 610 feet (190 m) tall, with a trapezoidal footprint that was 330 ft (100 m) long and 140 ft (43 m) wide.[5][6] Tishman Realty & Construction managed construction of the building.[5]

Features

Mechanical features

7 World Trade Center was constructed above a two-story Con Edison substation that had been located on the site since 1967.[7][8] The substation had a caisson foundation designed to carry the weight of a future building of 25 stories containing 600,000 sq ft (56,000 m2).[9] However, the final design for 7 World Trade Center was for a much larger building than originally planned when the substation was built.[10]: xxxviii  The structural design of 7 World Trade Center therefore included a system of gravity column transfer trusses and girders, located between floors 5 and 7, to transfer loads to the smaller foundation.[2]: 5  Existing caissons installed in 1967 were used, along with new ones, to accommodate the building. The 5th floor functioned as a structural diaphragm, providing lateral stability and the distribution of loads between the new and old caissons. Above the 7th floor, the building's structure was a typical tube-frame design, with columns in the core and on the perimeter, and lateral loads resisted by perimeter moment frames.[9]

A shipping and receiving ramp, which served the entire World Trade Center complex, occupied the eastern quarter of the 7 World Trade Center footprint. The building was open below the 3rd floor, providing space for truck clearance on the shipping ramp.[9] The spray-on fireproofing for structural steel elements was gypsum-based Monokote, which had a two-hour fire rating for steel beams, girders, and trusses, and a three-hour rating for columns.[1]: 11 

Mechanical equipment was installed on floors four through seven, including 12 transformers on the 5th floor. Several emergency generators installed in the building were used by the New York City Office of Emergency Management, Salomon Smith Barney, and other tenants.[1]: 13  In order to supply the generators, 24,000 gallons (91,000 L) of diesel fuel were stored below ground level.[11] Diesel fuel distribution components were located at ground level, up to the ninth floor.[12]: 35  The roof of the building included a small west penthouse and a larger east mechanical penthouse.[7]

Offices

Each floor had 47,000 sq ft (4,400 m2) of rentable office space, which made the building's floor plans considerably larger than most office buildings in the city.[13] In all, 7 World Trade Center had 1,868,000 sq ft (173,500 m2) of office space.[1]: 1  Two pedestrian bridges connected the main World Trade Center complex, across Vesey Street, to the third floor of 7 World Trade Center. In addition to several acquired artworks, from artists such as Frank Stella, Roy Lichtenstein, and Ross Bleckner, the lobby of 7 World Trade Center housed a large mural by artist Al Held, titled The Third Circle.[14]

History

7 World Trade Center in 1994
The building's footbridge and southeast corner on September 11, 2001

The groundbreaking ceremony was hosted on October 2, 1984.[8] The building opened in May 1987 as part of the World Trade Center.[15]

In June 1986, before construction was completed, developer Larry Silverstein signed Drexel Burnham Lambert as a tenant to lease the entire 7 World Trade Center building for $3 billion over a term of 30 years.[16] In December 1986, after the Boesky insider-trading scandal, Drexel Burnham Lambert canceled the lease, leaving Silverstein to find other tenants.[17] Spicer & Oppenheim agreed to lease 14 percent of the space, but for more than a year, as Black Monday and other factors adversely affected the Lower Manhattan real estate market, Silverstein was unable to find tenants for the remaining space. By April 1988, he had lowered the rent and made other concessions.[18]

In November 1988, Salomon Brothers withdrew from plans to build a large new complex at Columbus Circle in Midtown, instead agreeing to a 20-year lease for the top 19 floors of 7 World Trade Center.[19] The building was extensively renovated in 1989 to accommodate Salomon Brothers, and 7 World Trade Center alternatively became known as the Salomon Brothers building.[20] Most of the three existing floors were removed as tenants continued to occupy other stories, and more than 350 tons (U.S.) of steel were added to construct three double-height trading floors. Nine diesel generators were installed on the 5th floor as part of a backup power station. "Essentially, Salomon is constructing a building within a building – and it's an occupied building, which complicates the situation", said a district manager of Silverstein Properties.[20] According to Larry Silverstein, the unusual task was possible because it could allow "entire portions of floors to be removed without affecting the building's structural integrity, on the assumption that someone might need double-height floors."[20]

After the World Trade Center bombing of February 26, 1993, New York City mayor Rudy Giuliani decided to situate the emergency command center and associated fuel tanks at 7 World Trade Center. Although this decision was criticized in light of the events of 9/11, the fuel in the building is not believed to have contributed to the collapse of the building.[21][22]: 2 

Final tenants

The position of 7 WTC in relation to the other WTC buildings before September 11, 2001

At the time of the September 11 attacks, Salomon Smith Barney was by far the largest tenant in 7 World Trade Center, occupying 1,202,900 sq ft (111,750 m2) (64 percent of the building) which included floors 28–45.[1]: 2 [23] Other major tenants included ITT Hartford Insurance Group (122,590 sq ft/11,400 m2), American Express Bank International (106,117 sq ft/9,900 m2), Standard Chartered Bank (111,398 sq ft/10,350 m2), and the Securities and Exchange Commission (106,117 sq ft/9,850 m2).[23] Smaller tenants included the Internal Revenue Service Regional Council (90,430 sq ft/8,400 m2) and the United States Secret Service (85,343 sq ft/7,900 m2).[23] The smallest tenants included the New York City Office of Emergency Management,[24] National Association of Insurance Commissioners, Federal Home Loan Bank of New York, First State Management Group Inc., Provident Financial Management, and the Immigration and Naturalization Service.[23] The Department of Defense (DOD) and Central Intelligence Agency (CIA) shared the 25th floor with the IRS.[1]: 2  (The clandestine CIA office was revealed only after the 9/11 attacks.)[25] Floors 46–47 were mechanical floors, as were the bottom six floors and part of the seventh floor.[1]: 2 [25]

According to CoStar Group, floors 9 and 10 of 7 WTC were occupied by the Secret Service.[26] The CIA had offices on the 25th floor of 7 WTC, as reported by the Associated Press.[27] The National Institute of Standards and Technology's 2008 Final Report on the Collapse of World Trade Center Building 7 confirmed that floor 14 was vacant, and updated the news reports of CoStar and Associated Press from 2001 to show that Salomon Smith Barney leased floors 15 to 17.[28]: 9 

Fl# Companies
46-47 Salomon Smith Barney, Mechanical floor
28-45 Salomon Smith Barney
26-27 Salomon Smith Barney, Standard Chartered Bank
25 Department of Defense, Central Intelligence Agency
24 Salomon Smith Barney
23 Salomon Smith Barney, NYC Office of Emergency Management
22 Salomon Smith Barney, Federal Home Loan Bank
21 Salomon Smith Barney, First State Management Group, Hartford Financial Services Group
20 Salomon Smith Barney, Hartford Financial Services Group
19 Salomon Smith Barney, Hartford Financial Services Group, National Association of Insurance Commissioners Securities
18 Salomon Smith Barney, U.S. Equal Employment Opportunity Commission
15-17 Salomon Smith Barney
14 Vacant
13 Salomon Smith Barney, Provident Bank, American Express, Securities & Exchange Commission, Standard Chartered Bank
11-12 U.S. Securities and Exchange Commission
10 U.S. Secret Service, Standard Chartered Bank
9 United States Secret Service
8 American Express
7 American Express, Provident Bank, United States Secret Service, Mechanical floor
G, 1-6 Salomon Smith Barney, Mechanical floor

The total amount of space occupied by each tenant was:[28]: 9 [26][29]

Tenant Square Feet Leased Floors Occupied Industry
Salomon Smith Barney 1,202,900 0–6, 13, 15–24, 26-453M Financial Institutions
Internal Revenue Service Regional Council 90,430 24, 25 Government
U.S. Secret Service 85,343 9,10 Government
American Express Bank International 106,117 7, 8, 13 Financial Institutions
Standard Chartered Bank 111,398 10, 13, 26, 27 Financial Institutions
Provident Financial Management 9,000 7, 13 Financial Institutions
ITT Hartford Insurance Group 122,590 19–21 Financial Institutions
First State Management Group 4,000 21 Insurance
Federal Home Loan Bank 47,490 22 Financial Institutions
National Association of Insurance Commissioners Securities 22,500 19 Insurance
Securities & Exchange Commission 106,117 11, 12, 13 Government
New York City Office of Emergency Management 45,815 23 Government

9/11 and collapse

Main article: Collapse of 7 World Trade Center
7 World Trade Center on fire after the collapse of the Twin Towers on 9/11

Collapse

As the North Tower collapsed on September 11, 2001, heavy debris hit 7 World Trade Center, damaging the south face of the building[30]: 18 (PDF p. 22)  and starting fires that continued to burn throughout the afternoon.[2]: 16, 18  The collapse also caused damage to the southwest corner between floors 7 and 17 and on the south face between floor 44 and the roof; other possible structural damage included a large vertical gash near the center of the south face between floors 24 and 41.[2]: 17  The building was equipped with a sprinkler system, but had many single-point vulnerabilities for failure: the sprinkler system required manual initiation of the electrical fire pumps instead of being a fully automatic system; the floor-level controls had a single connection to the sprinkler water riser, and the sprinkler system required some power for the fire pump to deliver water.[31]: 11  Additionally, water pressure was low, with little or no water to feed sprinklers.[32]: 23–30 

  • The southeast corner of the building.
    The southeast corner of the building.
  • Heavy fire showing from WTC 7's eastern side.
    Heavy fire showing from WTC 7's eastern side.
  • Fire visible on WTC 7's north face.
    Fire visible on WTC 7's north face.
  • WTC 7 burning behind the Verizon Building.
    WTC 7 burning behind the Verizon Building.
  • WTC 7's rubble.
    WTC 7's rubble.

See also

References

  1. ^ a b c d e f g Gilsanz, Ramon; Edward M. DePaola; Christopher Marrion; Harold "Bud" Nelson (May 2002). "WTC7 (Chapter 5)" (PDF). World Trade Center Building Performance Study. FEMA. Archived (PDF) from the original on March 5, 2008. Retrieved February 17, 2008.
  2. ^ a b c d NIST NCSTAR1-A: Final Report on the Collapse of World Trade Center Building 7 (Report). National Institute of Standards and Technology. November 2008. Archived (PDF) from the original on July 21, 2011. Retrieved July 11, 2011.
  3. ^ "Questions and Answers about the NIST WTC 7 Investigation". NIST. National Institute of Standards and Technology. May 24, 2010. Archived from the original on August 27, 2010. Retrieved August 26, 2010.
  4. ^ Rudin, Mike (July 4, 2008). "9/11 third tower mystery 'solved'". BBC News. Archived from the original on September 3, 2014. Retrieved September 11, 2014.
  5. ^ a b Lew, H.S.; Bukowski, Richard W.; Nicholas J. Carino (September 2005). Design, Construction, and Maintenance of Structural and Life Safety Systems (NCSTAR 1-1). National Institute of Standards and Technology. p. 13.
  6. ^ "Seven World Trade Center (pre-9/11)". Emporis.com. Archived from the original on April 28, 2006. Retrieved May 7, 2006.
  7. ^ a b McAllister, T. P.; Gann, R. G.; Averill, J. D.; Gross, J. L.; Grosshandler, W. L.; Lawson, J. R.; McGrattan, K. B.; Pitts, W. M.; Prasad, K. R.; Sadek, F. H.; Nelson, H. E. (August 2008). "NIST NCSTAR 1–9: Structural Fire Response and Probable Collapse Sequence of World Trade Center Building 7". Final Reports of the Federal Building and Fire Investigation of the World Trade Center Disaster. National Institute of Standards and Technology. pp. 9–45. Archived from the original on August 7, 2020. Retrieved September 1, 2011.
  8. ^ a b Berger, Joseph (October 1, 1984). "Work Set on Last Trade Center Unit". The New York Times. ISSN 0362-4331. Archived from the original on March 1, 2018. Retrieved March 1, 2018.
  9. ^ a b c Salvarinas, John J. (1986). Seven World Trade Center, New York, Fabrication and Construction Aspects. Proceedings of the 1986 Canadian Structural Engineering Conference. Vancouver: Canadian Steel Construction Council.
  10. ^ Lew, H.S. (September 2005). "NIST NCSTAR 1-1: Design, Construction, and Maintenance of Structural and Life Safety Systems" (PDF). Final Reports of the Federal Building and Fire Investigation of the World Trade Center Disaster. National Institute of Standards and Technology. pp. xxxvii. Archived (PDF) from the original on May 30, 2010. Retrieved August 26, 2010.
  11. ^ Milke, James (Spring 2003). "Study of Building Performance in the WTC Disaster". Fire Protection Engineering. Archived from the original on February 12, 2008. Retrieved February 17, 2008.
  12. ^ Grill, Raymond A.; Johnson, Duane A. (September 2005). "NIST NCSTAR 1-1J: Documentation of the Fuel System for Emergency Power in World Trade Center 7" (PDF). Final Reports of the Federal Building and Fire Investigation of the World Trade Center Disaster. National Institute of Standards and Technology. Archived (PDF) from the original on May 30, 2010. Retrieved August 26, 2010.
  13. ^ Horsley, Carter B (October 25, 1981). "Lower Manhattan Luring Office Developers". The New York Times. ISSN 0362-4331. Archived from the original on August 29, 2021. Retrieved February 17, 2008.
  14. ^ See:
    "Al Held". National Gallery of Australia. Archived from the original on June 9, 2007. Retrieved May 29, 2007.
    Plagens, Peter (April 17, 1989). "Is Bigger Necessarily Better?". Newsweek.
  15. ^ "History of the World Trade Center". Port Authority of New York and New Jersey. Archived from the original on June 7, 2015. Retrieved May 26, 2015.
  16. ^ Scardino, Albert (July 11, 1986). "A Realty Gambler's Big Coup". The New York Times. ISSN 0362-4331. Archived from the original on August 30, 2021. Retrieved July 28, 2022.
  17. ^ Scardino, Albert (December 3, 1986). "$3 Billion Office Pact Canceled by Drexel". The New York Times. ISSN 0362-4331. Archived from the original on July 28, 2022. Retrieved July 28, 2022.
  18. ^ Berg, Eric N (April 7, 1988). "Talking Deals; Developer Plays A Waiting Game". The New York Times. ISSN 0362-4331. Archived from the original on March 25, 2008. Retrieved February 17, 2008.
  19. ^ Berkowitz, Harry (November 29, 1988). "Salomon to Move Downtown". Newsday.
  20. ^ a b c McCain, Mark (February 19, 1989). "The Salomon Solution; A Building Within a Building, at a Cost of $200 Million". The New York Times. ISSN 0362-4331. Archived from the original on March 19, 2007. Retrieved February 17, 2007.
  21. ^ See:
    Glanz, James; Lipton, Eric (December 20, 2001). "City Had Been Warned of Fuel Tank at 7 World Trade Center". The New York Times. ISSN 0362-4331. Archived from the original on November 28, 2007. Retrieved November 21, 2007.
    Barrett, Wayne (July 31, 2007). "Rudy Giuliani's 5 Big Lies About 9/11". Village Voice. Archived from the original on October 3, 2017. Retrieved October 20, 2017.
    "Transcript: Rudy Giuliani on 'FNS'". Fox News. May 14, 2007. Archived from the original on October 10, 2007. Retrieved September 29, 2007. Then why did he say the building – he said it's not – the place in Brooklyn is not as visible a target as buildings in Lower Manhattan
    Buettner, Russ (May 22, 2007). "Onetime Giuliani Insider Is Now a Critic". The New York Times. ISSN 0362-4331. Archived from the original on June 5, 2015. Retrieved June 12, 2007.
    "Giuliani Blames Aide for Poor Emergency Planning". New York Magazine. May 15, 2007. Archived from the original on May 17, 2007. Retrieved June 12, 2007.
  22. ^ National Construction Safety Team Advisory Committee. "Meeting of the National Construction Safety Team Advisory Committee, December 18, 2007" (PDF). Archived from the original (PDF) on February 12, 2017.
  23. ^ a b c d "Building: 7 World Trade Center". CNN. 2001. Archived from the original on October 13, 2007. Retrieved September 12, 2007.
  24. ^ Glanz, James; Eric Lipton (November 16, 2001). "Workers Shore Up Wall Keeping Hudson's Waters Out". The New York Times. ISSN 0362-4331. Archived from the original on September 17, 2009. Retrieved October 18, 2008.
  25. ^ a b "CIA Lost Office In WTC: A secret office operated by the CIA was destroyed in the terrorist attacks on the World Trade Center, seriously disrupting intelligence operations'". CBSNews.com / AP. November 5, 2001. Archived from the original on November 8, 2020. Retrieved February 17, 2008.
  26. ^ a b "Building: 7 World Trade Center". CoStar Group. CNN. 2001. Archived from the original on October 13, 2007. Retrieved October 26, 2010.
  27. ^ "Report: CIA Lost Office In WTC". CBS News. Associated Press. November 5, 2001. Archived from the original on November 10, 2023. Retrieved September 25, 2021.
  28. ^ a b NIST NCSTAR1-A: Final Report on the Collapse of World Trade Center Building 7 (PDF) (Report). National Institute of Standards and Technology. November 2008. Archived (PDF) from the original on June 19, 2019. Retrieved January 28, 2023.
  29. ^ Gilsanz, Ramon; et al. (September 2002). "Chapter 5: WTC Seven" (PDF). World Trade Center Building Performance Study (Report). Federal Emergency Management Agency. Archived from the original on August 20, 2011. Retrieved October 26, 2010.
  30. ^ "Interim Report on WTC 7" (PDF). Appendix L. National Institute of Standards and Technology. 2004. Archived from the original (PDF) on August 9, 2007. Retrieved August 20, 2007.
  31. ^ Grosshandler, William. "Active Fire Protection Systems Issues" (PDF). National Institute of Standards and Technology. Archived from the original on March 22, 2017. Retrieved September 11, 2007.
  32. ^ Evans, David D (September 2005). "Active Fire Protection Systems" (PDF). NIST. National Institute of Standards and Technology. Archived (PDF) from the original on May 31, 2010. Retrieved August 26, 2010.
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