Design and construction of the World Trade Center

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Construction of the World Trade Center
Construction of the World Trade Center

The design and construction of the World Trade Center was a process that began soon after World War II. The plans for building the World Trade Center, which involved uprooting the Radio Row neighborhood in Lower Manhattan, faced extensive controversy. The design and construction of the World Trade Center involved many new innovative techniques, such as the slurry wall. Construction of the World Trade Center began in the late 1960s, with the ribbon cutting ceremony taking place in 1973.

Contents

[edit] Plans for the World Trade Center

In 1942, Austin J. Tobin became the Executive Director of the Port Authority. During the post-World War II period, the United States thrived economically, with increasing international trade, and the concept of establishing a "world trade center" was conceived. In 1946, a bill was passed in the New York State Legislature that called for a "world trade center" to be established.[1] The World Trade Corporation was set up and a board appointed by New York Governor Thomas E. Dewey to develop plans for the project.[1] Architect John Eberson and his son Drew devised a plan that included 21 buildings over a ten-block area, at an estimated cost of $150 million.[2] In 1949, the World Trade Corporation was dissolved by the New York State Legislature, and plans for a "world trade center" were put on hold.[3]

During the post-war period, economic growth was concentrated in Midtown Manhattan, in part stimulated by the Rockefeller Center, which was developed in the 1930s. Meanwhile, Lower Manhattan was left out of the economic boom. One exception was the construction of One Chase Manhattan Plaza in the Financial District, by David Rockefeller, who led urban renewal efforts in Lower Manhattan.[4]

In 1958, Rockefeller established the Downtown-Lower Manhattan Association (DLMA), which commissioned Skidmore, Owings and Merrill to devise a plan for revitalizing Lower Manhattan. The plans, made public in 1960, called for a World Trade Center to be built on a 13-acre site along the East River, from Old Slip to Fulton Street and between Water Street and South Street.[5] The complex would include a 900-foot long exhibition hall, and a 50-70 story building, with some of its upper floors used as a hotel.[6] Other amenities would include a theater, shops, and restaurants.[7] The plan also called for a new securities exchange building, which Downtown-Lower Manhattan Association hoped would house the New York Stock Exchange.[5] David Rockefeller suggested that the Port Authority would be a logical choice for taking on the project.[5] Rockefeller argued that the Trade Center would provide great benefits in facilitating and increasing volume of international commerce coming through the Port of New York.[7] Given the importance of New York City in global commerce, Port Authority director Austin J. Tobin remarked that the proposed project should be the World Trade Center, and not just a "world trade center".[8]

After a year-long review of the proposal, the Port Authority formally backed the project on March 11, 1961.[9] Objections to the plan came from New Jersey Governor Robert B. Meyner, who resented that New York would be getting this $335 million project.[4] Meanwhile, New Jersey's Hudson and Manhattan Railroad (H&M) was facing bankruptcy. Towards the end of 1961, negotiations with outgoing New Jersey Governor Meyner reached a stalemate. In December 1961, Tobin met with newly elected New Jersey Governor Richard J. Hughes, and made a proposal to shift the World Trade Center project to a west side site where the Hudson Terminal was located.[10] In acquiring the Hudson & Manhattan Railroad, the Port Authority would also acquire the Hudson Terminal and other buildings which were deemed obsolete.[10] On January 22, 1962, the two states reached an agreement to allow the Port Authority to take over the railroad and to build the World Trade Center on Manhattan's lower west side.[11]

Even once the agreement between the states of New Jersey, New York, and the Port Authority was finalized, the World Trade Center plan faced continued controversy. The site for the World Trade Center was the location of Radio Row, which was home to hundreds of commercial and industrial tenants, property owners, small businesses, and approximately 100 residents.[4] The World Trade Center plans involved evicting these business owners, some of whom fiercely protested the forced relocation.[4] In June 1962, a group representing approximately 325 shops and 1,000 other affected small businesses filed an injunction, challenging the Port Authority's power of eminent domain.[12] The dispute with local business owners worked its way through the court system, up to the New York State Court of Appeals, which in April 1963 upheld the Port Authority's right of eminent domain, saying that the project had a "public purpose".[13][14] On November 12, 1963, the United States Supreme Court refused to accept the case.[15][16] Under the state law, the Port Authority was required to assist business owners in relocating, though many business owners regarded what the Port Authority offered as inadequate.[15][17]

Private real estate developers and members of the Real Estate Board of New York also expressed concerns about this much "subsidized" office space going on the open market, competing with the private sector when there was already a glut of vacancies.[4][18] An especially vocal critic was Lawrence A. Wien, owner of the Empire State Building, which would lose its title of tallest building in the world.[4][19] Wien organized a group of builders into a group called the "Committee for a Reasonable World Trade Center" which demanded the project be scaled down.[20] In future years, the payments would rise as the overall real estate tax rate rises.[21]

In January 1964, the Port Authority inked a deal with the State of New York to locate government offices at the World Trade Center.[22] The Port Authority began signing up some commercial tenants in the Spring and Summer of 1964, including several banks.[23] In 1965, the Port Authority signed up the United States Customs Service as a tenant.[24]

A final obstacle for the Port Authority was getting approval from New York City Mayor John Lindsay and the New York City Council. They raised concerns about the limited extent that the Port Authority involved the city in the negotiations and deliberations. Negotiations between The City of New York and the Port Authority centered on tax issues. A final agreement was made on August 3, 1966, that the Port Authority would make annual payments to the city in lieu of taxes, for the 40 percent of the World Trade Center leased to private tenants.[25]

[edit] Design

Original architectural and engineering model
Original architectural and engineering model

On September 20, 1962, the Port Authority announced the selection of Minoru Yamasaki as lead architect, and Emery Roth & Sons as associate architects.[26] Yamasaki came up with the idea of twin towers. To meet the Port Authority's requirement to build 10 million square feet of office space, the towers would each be 110-stories tall. Yamasaki remarked that the "obvious alternative, a group of several large buildings, would have looked like a housing project".[27]

Yamasaki's design for the World Trade Center was unveiled to the public on January 18, 1964, with an eight-foot model.[27]

The buildings were designed with narrow office windows, only 18 inches wide, which reflected on Yamasaki's fear of heights and desire to make building occupants feel secure.[28]

[edit] Structural design

The World Trade Center included many structural engineering innovations in skyscraper design and construction, which allowed the buildings to reach new heights and become the tallest in the world. Traditionally, skyscrapers used a skeleton of columns distributed throughout the interior to support building loads, with interior columns disrupting the floor space. Elevators were another limiting factor in building heights. The taller the building, the more elevators are needed to service the building and more space-consuming elevator banks.[29]

The World Trade Center used high-strength, load bearing perimeter steel columns that were spaced closely together to form a strong, rigid wall structure. In this framed tube structures, there were 59 perimeter columns on each side of the building, with additional columns within the core. The perimeter columns supported virtually all lateral loads, such as wind loads, and shared the gravity loads with the core columns.[30]

[edit] Perimeter columns

The perimeter columns supported virtually all lateral loads, such as wind loads, and shared the gravity loads with the core columns. The perimeter structure was constructed with extensive use of prefabricated modular pieces, which consisted of three columns, three stories tall, connected together by spandrel plates. Above the seventh floor there were 59 perimeter columns, closely spaced along each face of the building.[31] The perimeter columns had a square cross section, 14 inches on a side (36 cm), and were constructed of welded steel plate.[30] The thickness of the plates and grade of steel were varied over the height of the tower, ranging from 36 ksi to 100 ksi, with the steel strength and plate thickness decreasing with height.[30] The spandrel plates were welded to the columns at the fabrication shop. The modular pieces were typically 52 inches (1.3 m) deep, and extended for two full floors and half of two more floors.[30] Adjacent modules were bolted together, with the splices occurring at mid-span of the columns and spandrels. The spandrel plates were located at each floor, and served to transmit shear flow between columns, thus allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically, so the column splices between adjacent modules were not at the same floor.[30] All columns were founded on bedrock, which unlike Midtown Manhattan, where the bedrock is shallow, is at 65 feet (20m) below the surface. Yamasaki's design called for the building facades to be sheathed in aluminium-alloy.[32]

[edit] Core

The building's core housed the elevator and utility shafts, restrooms, three stairwells, and other support spaces. The core in 1 WTC was oriented with the long axis east to west, while that of 2 WTC was oriented north to south. The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower.[30] The columns tapered with height, and consisted of welded box-sections at lower floors and rolled wide-flange sections at upper floors. All of the elevators and stairwells were located in the core.

[edit] Floor system

The floors supported their own weight, as well as live loads, provided lateral stability to the exterior walls, and distributed wind loads among the exterior walls. The floors consisted of 4 inch thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The floors were connected to the perimeter spandel plates with vicsoelastic dampers, which helped reduce the amount of sway felt by building occupants.

The large, column-free space between the perimeter and core was bridged by pre-fabricated floor trusses. The floors supported their own weight, as well as live loads, provided lateral stability to the exterior walls, and distributed wind loads among the exterior walls. The floors consisted of 4 inch (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses had a span of 60 feet (18.2 m) in the long-span areas and 35 feet (11.0 m) in the short span area.[30] The trusses connected to the perimeter at alternate columns, and were therefore on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandel plates with vicsoelastic dampers, which helped reduce the amount of sway felt by building occupants. The trusses supported a 4-inch-thick (10 cm) lightweight concrete floor slab, with shear connections for composite action.[30]

[edit] Hat trusses

Hat trusses located from the 107th floor to the top of the buildings were designed to support a tall communications antenna on top of each building. Though, only WTC1 (north tower) actually had an antenna.

Hat trusses (or "outrigger truss") located from the 107th floor to the top of the buildings were designed to support a tall communications antenna on top of each building.[30] Though, only WTC1 (north tower) actually had an antenna. The truss system consisted of six trusses along the long axis of core and four along the short axis. This truss system allowed some load redistribution between the perimeter and core columns and supported the transmission tower.

[edit] Design innovations

A typical floor layout and elevator arrangement of the WTC towers.
A typical floor layout and elevator arrangement of the WTC towers.

The tube-frame was a major innovation in skyscraper design, allowing open floor plans and more rentable space. To solve the problem of wind sway or vibration in the construction of the towers, chief engineer Leslie Robertson took a then unusual approach — instead of bracing the buildings corner-to-corner or using internal walls, the towers were essentially hollow steel tubes surrounding a strong central core. The 208 feet (63.4 m) wide facade was, in effect, a prefabricated steel lattice, with columns on 39 inch (100 cm) centers acting as wind bracing to resist all overturning forces; the central core took the majority of the gravity loads of the building. A very light, economical structure was built by keeping the wind bracing in the most efficient area, the outside surface of the building, thus not transferring the forces through the floor membrane to the core, as in most curtain-wall structures. The core supported the weight of the entire building and the outer shell containing 240 vertical steel columns called Vierendeel trusses around the outside of the building, which were bound to each other using ordinary steel trusses. In addition, 10,000 dampers were included in the structure. With a strong shell and core such as this, the exterior walls could be simply light steel and concrete. With the massive core and lightweight shell for structural integrity, Robertson created a tower that was extremely light for its size.

[edit] Elevators

The buildings were also the second supertall buildings to use sky lobbies, after the John Hancock Center in Chicago.[33] Skylobbies are floors where commuters can switch from an express elevator that goes only to the sky lobbies to a local elevator that goes to each floor in a section. The local elevators were stacked on top of each other, within the same elevator shaft. Located on the 44th and 78th floors of each tower, the sky lobbies enabled the elevators to be used efficiently while taking up a minimum of valuable office space.[34] Altogether, the World Trade Center had 95 express and local elevators.[35] This system was inspired by the New York City Subway system, whose lines include local stations where local trains stop and express stations where all trains stop.[36]

[edit] Other innovations

Other innovations included

  • Two-way truss framed floors
  • Prefabricated columns and spandrel plates
  • Sprayed fire-resistant material
  • Use of viscoelastic dampers - reduced oscillation of the building
  • Subway-style elevators (local and express)

[edit] Criticism

The World Trade Center design brought criticism of its aesthetics from the American Institute of Architects and other groups.[37][32] Lewis Mumford, author of The City in History and other works on urban planning, criticized the project and described it and other new skyscrapers as "just glass-and-metal filing cabinets".[38]

Television broadcasters raised concerns that the Trade Center would cause interference in television reception for viewers in the New York City area.[39] In response to these concerns, the Port Authority offered to provide new television transmission facilities at the World Trade Center.[40]

The Linnaean Society of the American Museum of Natural History also opposed the Trade Center project, citing hazards the buildings would impose on migrating birds.[41]

[edit] Construction

In March 1965, the Port Authority began acquiring property at the World Trade Center site.[42] Work began on March 21, 1966 to demolish buildings and clear the site for construction of the World Trade Center.[43] The Ajax Wrecking and Lumber Corporation was hired to do the demolition work.[43]

[edit] Slurry wall

The site of the World Trade Center was located on landfill, with the bedrock located 65 feet below.[44] In order to construct the World Trade Center, it was necessary to build the "bathtub", with the slurry wall along the West Street side of the site, which serves the purpose of keeping water from the Hudson River out. The slurry method involves digging a trench, and as excavation proceeds, filling the space with a "slurry" mixture, comprised of bentonite which plugs holes and keeps water out. When the trench was dug out, a steel cage was inserted, with concrete poured in, forcing the "slurry" out. The "slurry" method was devised by Port Authority chief engineer, John M. Kyle, Jr.

Some of the land consists of fill material that was added to expand the Manhattan shoreline. Unlike Midtown Manhattan, where the bedrock is shallow, at the World Trade Center site, bedrock is 65 feet below the surface.[44] In order to construct the World Trade Center, it was necessary to build the "bathtub", with the slurry wall along the West Street side of the site, to keep the Hudson River out.

In the slurry method, excavators dig a trench and, as excavation proceeds, fill the space with a "slurry" mixture of bentonite, which plugs holes and keeps water out. After digging the trench, builders insert a steel cage and pour in concrete, forcing the slurry out. Port Authority chief engineer John M. Kyle, Jr. devised the slurry method.

Towards the end of 1966, work began on building the slurry wall, which was lead by Montreal-based Icanda, a subsidiary of an Italian engineering firm, Impresa Costruzioni Opere Specializzate (I.C.O.S.).[45] It took fourteen months for the slurry wall to be completed, which was necessary before excavation of material from the interior of the site could begin.[45]

[edit] North and South Towers

Construction on the World Trade Center's foundations officially began on August 5, 1966 with groundbreaking.[46] Construction work began on the North Tower in August 1968 with construction beginning on the South Tower by January 1969. [47]

In January 1967, $74 million in contracts were awarded to the Pacific Car and Foundry Company, Laclede Steel Company, Granite City Steel Company, and Karl Koch Erecting Company to supply steel for the project.[48] Karl Koch was also hired to do all the work of erecting the steel, and a contract for work on the aluminium facade was awarded to the Aluminum Company of America.[48] Tishman Realty & Construction was hired in February 1967 to oversee construction of the project.[49]

Construction of World Trade Center 1 (North Tower) was completed on December 23, 1970,[50] with World Trade Center 2 (South Tower) completed on July 19, 1971.[51] The buildings were dedicated on April 4, 1973, with Tobin, who resigned the year before, absent from the ceremonies.[52]

[edit] Battery Park City

Main article: Battery Park City, Manhattan

Construction of the World Trade Center involved excavating 1.2 million cubic yards of material.[53] Rather than transporting this material at great costs out to sea or to landfills in New Jersey, the fill material was used to expand the Manhattan shoreline across West Street.[53] Work to demolish the piers began on January 5, 1967, including Pier 7 to Pier 11 which were all constructed around 1910.[54] The demolition work moved forward, despite conflicts between David Rockefeller, Governor Nelson Rockefeller, and Mayor John Lindsay regarding plans for Battery Park City.[55]

Landfill material from the World Trade Center was used to add land, and a cellular cofferdam was constructed to retain the material.[44] The result was a 700 feet extension into the Hudson River, running six blocks or 1,484 feet long.[53] This land was a "gift" to New York City, allowing more tax-generating developments in Battery Park City.[56]

[edit] Costs

The original estimates put forth by the Port Authority had the costs for construction of the World Trade Center at $350 million — an optimistic figure.[57] In December 1966, the Port Authority announced increased cost estimates, bringing total estimated costs to $575 million.[58] This announcement brought criticism of the project from private real estate developers, the New York Times, and others in New York City.[59] The critics charged that the Port Authority figure was unrealistically low estimate, and they estimated the project would end up costing $750 million.[60] When the World Trade Center twin towers were completed, the total costs to the Port Authority had reached $900 million.[61]

[edit] See also

[edit] References

  1. ^ a b "Dewey Picks Board for Trade Center", The New York Times, July 6, 1946.
  2. ^ Crisman, Charles B.. "Plans are Tabled for Trade Center", The New York Times, November 10, 1946.
  3. ^ "Lets Port Group Disband, State Senate for Dissolution of World Trade Corporation", The New York Times, March 11, 1949.
  4. ^ a b c d e f Gillespie, Angus K. (1999). "Chapter 1", Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press. 
  5. ^ a b c Grutzner, Charles. "A World Center of Trade Mapped Off Wall Street", The New York Times, January 27, 1960.
  6. ^ Koch, Karl III (2002). Men of Steel: The Story of the Family That Built the World Trade Center. Three Rivers Press, p. 173. 
  7. ^ a b "Text of Trade Center Report by the Downtown-Lower Manhattan Association", The New York Times, January 27, 1960.
  8. ^ "Tobin Says Proposed Center Should Be World's Best", The New York Times, May 5, 1960.
  9. ^ "355 Million World Trade Center Backed by Port Authority Study", The New York Times, March 12, 1961.
  10. ^ a b Grutzner, Charles. "Port Unit Backs Linking of H&M and Other Lines", The New York Times, December 29, 1961.
  11. ^ Wright, George Cable. "2 States Agree on Hudson Tubes and Trade Center", The New York Times, January 23, 1962.
  12. ^ Clark, Alfred E.. "Injunction Asked on Trade Center", The New York Times, June 27, 1962.
  13. ^ Crowell, Paul. "World Trade Center Here Upheld by Appeals Court", The New York Times, April 5, 1963.
  14. ^ "Merchants Ask Supreme Court to Bar Big Trade Center Here", The New York Times / Associated Press, August 26, 1963.
  15. ^ a b Arnold, Martin. "High Court Plea is Lost by Foes of Trade Center", The New York Times, November 13, 1963.
  16. ^ 375 US. 4 - Courtesty Sandwich Shop, Inc., et al. v. Port of New York Authority
  17. ^ Apple, Jr. R.W.. "Port Body Raises Relocation Aid", The New York Times, November 16, 1963.
  18. ^ Knowles, Clayton. "New Fight Begun on Trade Center", The New York Times, February 14, 1964.
  19. ^ Ennis, Thomas W.. "Critics Impugned on Trade Center", The New York Times, February 15, 1964.
  20. ^ Knowles, Clayton. "All Major Builders are Said to Oppose Trade Center Plan", The New York Times, March 9, 1964.
  21. ^ Smith, Terence. "Mayor Signs Pact on Trade Center", The New York Times, January 26, 1967.
  22. ^ Sibley, John. "State Will Rent at Trade Center", The New York Times, January 14, 1964.
  23. ^ "4th Bank Signed by Trade Center", The New York Times, July 14, 1964.
  24. ^ Fowler, Glenn. "Customs to Move to Trade Center", The New York Times, July 7, 1965.
  25. ^ Smith, Terence. "City Ends Fight with Port Body on Trade Center", The New York Times, August 4, 1966.
  26. ^ Esterow, Milton. "Architect Named for Trade Center", The New York Times, September 21, 1962.
  27. ^ a b Huxtable, Ada Louise. "A New Era Heralded", The New York Times, January 19, 1964.
  28. ^ Pekala, Nancy. "Profile of a lost landmark; World Trade Center", Journal of Property Management, November 1, 2001.
  29. ^ Huxtable, Ada Louise. "Biggest Buildings Herald New Era", The New York Times, January 26, 1964.
  30. ^ a b c d e f g h i Final Report on the Collapse of the World Trade Center (chapter 1). National Institute of Standards and Technology (NIST) (September 2005).
  31. ^ National Construction Safety Team (September 2005). Final Report on the Collapse of the World Trade Center Towers. NIST, p. 6. 
  32. ^ a b Huxtable, Ada Louise. "Who's Afraid of the Big Bad Buildings", The New York Times, May 29, 1966.
  33. ^ Otis History: The World Trade Center. Otis Elevator Company. Retrieved on December 7, 2006.
  34. ^ Gillespie, Angus K. (1999). "Chapter 2", Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press. 
  35. ^ Ruchelman, Leonard I. (1977). The World Trade Center: Politics and Policies of Skyscraper Development.. Syracuse University Press, p. 11. 
  36. ^ Gillespie, Angus K. (1999). Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press, p. 76. 
  37. ^ Steese, Edward. "Marring City's Skyline", The New York Times, March 10, 1964.
  38. ^ Whitman, Alden. "Mumford Finds City Strangled By Excess of Cars and People", The New York Times, March 22, 1967.
  39. ^ Schumach, Murray. "TV Group Objects to Trade Towers", The New York Times, February 20, 1966.
  40. ^ "TV Mast Offered on Trade Center", The New York Times, February 24, 1966.
  41. ^ Knowles, Clayton. "Big Trade Center Called Bird Trap", The New York Times, March 16, 1967.
  42. ^ Ingraham, Joseph C.. "Port Agency Buys Downtown Tract", The New York Times, March 29, 1965.
  43. ^ a b Gillespie, Angus K. (1999). Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press, p. 61. 
  44. ^ a b c Iglauer, Edith. "The Biggest Foundation", The New Yorker, November 4 1972.
  45. ^ a b Gillespie, Angus K. (1999). Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press, p. 68. 
  46. ^ "Jackhammers Bite Pavement to Start Trade Center Job", The New York Times, August 6, 1966.
  47. ^ Timeline: World Trade Center chronology, PBS - American Experience
  48. ^ a b "Contracts Totaling $74,079,000 Awarded for the Trade Center", The New York Times, January 24, 1967.
  49. ^ Kihss, Peter. "Trade Center Job To Go To Tishman", The New York Times, February 27, 1967.
  50. ^ Timeline: World Trade Center chronology, PBS - American Experience
  51. ^ Timeline: World Trade Center chronology, PBS - American Experience
  52. ^ Darton, Eric (1999) Divided We Stand: A Biography of New York's World Trade Center, Chapter 6, Basic Books.
  53. ^ a b c Gillespie, Angus K. (1999). Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press, p. 71. 
  54. ^ Horne, George. "Demolition Begun on 5 City Piers", The New York Times, January 5, 1967.
  55. ^ Roberts, Steven V.. "Conflicts Stall Landfill Plans", The New York Times, January 17, 1967.
  56. ^ "New York Gets $90 Million Worth of Land for Nothing", Engineering News Record, April 18, 1968.
  57. ^ Gillespie, Angus K. (1999). Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press, p. 70. 
  58. ^ Gillespie, Angus K. (1999). Twin Towers: The Life of New York City's World Trade Center. Rutgers University Press, p. 69. 
  59. ^ "Questions on the Trade Center", The New York Times, December 24, 1966.
  60. ^ Phillips, McCandlish. "Estimate Raised for Trade Center", The New York Times, December 29, 1966.
  61. ^ Cudahy, Brian J. (2002) Rails Under the Mighty Hudson: The Story of the Hudson Tubes, the Pennsy Tunnels, and Manhattan Transfer, Chapter 3, Fordham University Press.

[edit] External links

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