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September 12, 2001

The twin towers were built between 1966 and 1973 to the design of Minoru Yamasaki (deceased). To gain an elegant form to house the huge rentable area required, he chose to have two tall slender towers.

To make this structurally viable, Skilling, Helle, Christiansen, Robertson Structural Engineers gave the towers an external steel lattice that acted as a wind brace. This system was first used at the IBM building in Seattle. This system also eradicated the need for internal columns - these would have been next to impossible on buildings of this size due to the required size of the columns in the lower part of the structure. The lattice was shaped to appear as oversized window mullions, spaced at 39 inches. They really were huge, but felt reassuring for anyone with a sense of vertigo.

This was also the first building to employ the skylobby system - this is a highly efficient way of working the lifts to service the huge building population. Express lifts would take people to "skylobbies" from where there could ascend to their own "local level". This cut the number of lifts down, again increasing leasable are per floor to a percentage more like that of a conventional lowrise building.

In 1993, a massive bomb exploded in the World trade Center's underground carpark, killing six people and injuring 1042. The bomb failed to budge the buildings due to the exoskeletal structural system, which had little reliance on the foundations of the core.

On September 11, 2001, the twin towers and tower 7 were reduced to rubble after terrorists hijacked two american Boeing 767s and flew them into the towers. The tragedy still unfolds. Minoru Yamasaki Architects have this to say:

"MYA is shocked and outraged at this terrible tragedy. Mere words cannot express the depth of our grief and our thoughts and prayers go out to the victims and there families."

statistics:
floor area: 40,000 sq. feet in each of the upper floors.Total 9,6000,000 square feet gross.
height: 110 floors, rising 412metres.
elevators: 99.
population: 50,000, plus 70,000 daily visitors.
tallest tower: until 1974 when Sears Tower overtook them.

by Peter Johns

internal links:

• butterpaper news : why did they fall?
• butterpaper editorial 09/01: the future of tall buildings
• butterpaper editorial 09/02: the architects fight back
  

external links:

• world trade center NY official history - contains many photos of the buildings' construction. [06/04]
• world trade center virtual tour
• great buildings profile
• metropolis magazine articles
  
• minoru yamasaki profile
  
• minoru yamasaki architects (MYA)
• JOM - a late 2001 article looking in depth at the reasons for the WTC's collapse.[06/04]
• The Height of Ambition - a New York Times feature in 2002 that tells the story of the building from when it was a gleam in a developer's eye. Registration req'd. [06/04]

news:

• Twisting New York skyscraper to replace twin towers
  Final tower design unveiled.
  (Stuff NZ 20.12.03)
  
• Architects in clash of towering egos
  Libeskind and Childs not chummy any more.
  (Oz 12.12.03)
  
• Trade Center Arguments Fade, and a Single Vision Is Emerging
  Re: WTC. Santiago Calatrava takes the Port Authority building.
  (Yahoo 01.08.03)
  
• WTC competition draws 5,200 entries
  Re: New York WTC memorial.
  (SMH 18.7.03
• New York Chooses Plan for Spire, Pit at WTC Site
  Re: WTC New York. The rumour is: Libeskind wins
  (YAHOO 26.02.03)
• Living With Our Mistake
  Re: New York WTC. Muschamp vs. Libeskind. Who is getting it wrong?
  (SLATE 25.02.03)
• Building on the lessons of history
  Re: New York. Henry CK Liu puts the WTC memorial in context with just about all western architecture.
  (Asia Times 13.02.03)
• This Stop, 65th Floor, Rain Forest
  Re: New York. Both WTC finalists incorporate skygardens.
  (NY Times 13.02.03) Rego required
• Balancing Reason and Emotion in Twin Towers Void
  Re: New York. Muschamp review of finalists.
  (NY Times 06.02.03) Rego required
• 2 Teams of Architects to Compete for Ground Zero Design
  Re: New York. Finalists chosen for WTC site design: Libeskind and THINK.
  (NY Times 04.02.03) Rego required
• WTC Decision Is Pushed Back
  Re: New York. Finalists to be chosen in coming days.
  (Newsday 29.01.03)
  
• Gaudi design proposed for WTC
  Re: WTC. BBC digs up pictures of the Gaudi tower design mentioned earlier.
  (BBC 23.01.03) KH
• New Yorkers debate WTC plans
  Re: New York. Public interest in new proposal mounts, hearings to start soon.
  (BBC 13.01.03) KH
• Appraisals of Ground Zero Designs
  Re: WTC designs. The big names gather. "Everyone is so warm and fuzzy and self-congratulatory it distresses me".
  (NY Times 09.01.03, KMCF) Rego required
• Rediscovering and Celebrating the Vertical Life
  Re: New York. New WTC designs by Libeskind, Foster, Meier et al examined. Includes interactive feature.
  (NYT 19.12.02) Rego Required
• World Trade Center architects aim high
  Re: New York. 5 big proposals for the site. The plans are online too.
  (BBC 18.12.02) KH
• At Ground Zero, the Freshest Architecture May Be the Answer
  Re: New York. On the eve of the unveiling of the new designs for the WTC, Herbert Muschamp discusses why architecture needs to be of its day.
  (NYT 18.12.02) rego required
• Emotional Visit to Ground Zero for Architects
  Re: New York. WTC. Foster, Libeskind, Eisenman et al make a site visit. (NYT 13.10.02) Rego req'd
  
• For Construction at Trade Center Site, the Future Is Now
  Re: New York. WTC. So much for the competitions, they've already started building. "All we planned to put in there was just a subway box." (NYT 10.10.02) Rego req'd
• Lofty battles at the WTC
  Re: New York. Planning vs. architecture and the explosion of the six pack. (SF Chronicle 04.08.02)
• Fighting to Live as the Towers Died
  Re: Twin Towers. A detailed report into what happened in the last hour in the towers. Includes a flash presentation called 'inside the towers' that has good sectional images of the buildings (but is difficult to watch).
  (NY TIMES 26.05.02) Rego Required
• Rich Firms, Poor Ideas on Towers Site
  Re: New York. Herbert Muschamp examines the history behind the players in the rebuild of the WTC site. How independent are the independent bodies?
  (YAHOO/NYT 18.04.02)
• Report sees lower towers that can empty faster
  Re: WTC site. American Society of Civil Engineers advises on ways to make replacement buildings more secure. (NYTimes 28.03.02) Registration required.
• How quickly a city can grow
  Re: World Trade centre site, Witold Rybczynski writes that there should be a rush to build, and that this should not be a problem.
  (NY Times 25.03.02)
  Requires registration.
• How to Save Ground Zero: An Immodest Proposal
  Re: The WTC Site. Historical and current difficulties with memorials. (Atlantic 28.02.02)
• First Tower to Fall Was Hit at Higher Speed, Study Finds
  Re: Twin Towers, plane speeds were "off the chart". Discusses distribution through the buildings of energy from impact.
  (NY Times 23.02.02)
  Requires registration.
• The Towers Tomorrow
  Re: New York, more ideas for the hole. Cesar Pelli and William Pedersen speak. (NY Village Voice 16.01.02)
• Winter Garden at the Attack Site Looks to Spring
  Re: New York, Cesar Pelli's World Financial Center and Winter Garden, reconstruction amid the debris (NYTimes 15.01.02)
  Registration required.
• Architects aiming high despite Twin Towers
  Re: Tall buildings and the future of tall architecture - by Deyan Sujic.
  (Otago Daily Times 14.01.02)
• Leaping From One Void Into Others
  Re: Twin Towers, that and other voids. By Herbert Muschamp (NYTimes 23.12.01)
  registration required.
• Faulty Fireproofing Is Reviewed as Factor in Trade Center Collapse
  Re: Twin Towers, problems identified with fireproofing, used to fall off in high winds (NYTimes 13.12.01)
  registration required.
• Q'n'A VincentScully
  (Metropolis 12.01)
  
• The Tower Builder
  An interview with the engineer. "The World Trade Center was a team effort, but the collapse of the World Trade Center is my responsibility, and that's the way I feel about it." Also includes a detailed description of the structural system, and an interview with a demolition specialist: "Far more people would have died if those buildings had been built differently. A conventional frame building would have fallen immediately—no question. Only a tube structure could have taken that hit and survived."
  (New Yorker 19.11.01)
• The Commemorative Beauty of Tragic Wreckage
  Re: New York, holding onto the fragments.
  (NYTimes 11.11.01)
  May require registration
• Power, Imagination and New York's Future
  Re: New York, problems in the architecture world as redevelopment beckons.
  (NYTimes 28.10.01)
  May require registration
• Locked doors stopped rooftop rescue in towers
  Re: New York, twin towers, doors locked at the top after 1993 "publicity stunts".
  (SMH 24.10.01)
• Tall Dreams and Premiums
  Re: Rising premiums and lower rents for tall buildings.
  (IHT 05.10.01)
• Towers of Light
  A proposal to illuminate the sky in place of the towers.
  (New Yorker 01.10.01)
• Building Plans
  Paul Goldberger writes. "Now that the Trade Center has become a martyr to terrorism, I suspect that architectural criticism of it will cease altogether. It has become a noble monument of a lost past."
  (New Yorker 24.09.01)
• A City Transformed: Designing 'Defensible Space'
  Re: New York, Antony Vidler writes about making buildings safe through the past century.
  (NYTimes 23.09.01)
  May require registration
• Engineers Say Buildings Near Trade Center Held Up Well
  Re: New York, adjacent buildings report.
  (NYTimes 20.09.01)
  May require registration
• Engineers Tackle Havoc Beneath Trade Center
  Re: New York, twin towers, the dangers of excavation, the 'bath tub'.
  (NYTimes 18.09.01)
  May require registration
• Satellite photo of lower manhatten
  (CNN)
• The "nice" townplanner who killed thousands
  Re: Twin towers, suspect was a planning and urban development in Hamburg and may have studied architecture in Cairo. (16.09.01)
• A skyline diminished
  A Sydney Morning Herald map of the area showing buildings under threat of collapse. (16.09.01)
• Reaching for the Sky
  Re: New York, twin towers, Minuro Yamasaki Architect - detailed profile. Comments on skyscarpers from Sir Norman Foster.(Guardian 15.09.01)
• World Trade Centre - New York - Some Engineering Aspects
  Sydney University's Department of Civil Engineering closely examines the structure and collapse of the World Trade Centre towers (14.09.01)
• Why the towers collapsed
  A Sydney Morning Herald graphic. (13.09.01)
• profile of minuro yamasaki, architect of the WTC (det news)
  
• Watching a Creation From Infancy to Rubble
  Re: New York, twin towers, Minuro Yamaski Architects talk, Robert Stern also. (NYTimes 14.09.01) May require registration
• Buildings Were Unprepared to Withstand Such an Impact
  Re: Detailed description of collapse of structure, Cesar Pelli comments.
• The Biggest Foundation
  A republished article from 1972 describing the difficulties faced in excavating and maintaining the underground train system.
  (New Yorker 13.09.01)
  
• radio interview with one WTC architect, Aaron Swirski on September 11(Jerusalem Post)