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Context of 'December 14, 2007: NIST Fact Sheet Responds to Questions about Its WTC Investigation'

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The hole caused by the Flight 11 crash.The hole caused by the Flight 11 crash. [Source: Reuters]Flight 11 slams into the WTC North Tower (Building 1). Hijackers Mohamed Atta Waleed Alshehri, Wail Alshehri, Abdulaziz Alomari, and Satam Al Suqami presumably are killed instantly, and many more in the tower will die over the next few hours. Seismic records pinpoint the crash at 26 seconds after 8:46 a.m. [CNN, 9/12/2001; New York Times, 9/12/2001; North American Aerospace Defense Command, 9/18/2001; USA Today, 12/20/2001; Federal Emergency Management Agency, 5/1/2002, pp. 1-10; New York Times, 5/26/2002; USA Today, 8/12/2002; Associated Press, 8/21/2002; Newsday, 9/10/2002] The NIST report states the crash time to be 8:46:30. [National Institute of Standards and Technology, 9/2005, pp. 19] The 9/11 Commission Report states the crash time to be 8:46:40. [9/11 Commission, 7/24/2004, pp. 7] Investigators believe the plane still has about 10,000 gallons of fuel (see 8:57 a.m. September 11, 2001). [New York Times, 5/26/2002] The plane strikes the 93rd through 99th floors in the 110-story building. No one above the crash line survives; approximately 1,360 people die. Below the crash line, approximately 72 die and more than 4,000 survive. Both towers are slightly less than half full at the time of the attack, with between 5,000 to 7,000 people in each tower. This number is lower than expected. Many office workers have not yet shown up to work, and tourists to the observation deck opening at 9:30 A.M. have yet to arrive. [USA Today, 12/20/2001; National Institute of Standards and Technology, 9/2005, pp. 20-22] The impact severs some columns on the north side of the North Tower. Each tower is designed as a “tube-in-tube” structure and the steel columns which support its weight are arranged around the perimeter and in the core. The plane, which weighs 283,600 lb and is traveling at an estimated speed of around 430 mph (see October 2002-October 2005), severs 35 of the building’s 236 perimeter columns and damages another two. The damage to the South Tower’s perimeter will be similar (see 9:03 a.m. September 11, 2001). [National Institute of Standards and Technology, 9/2005, pp. 5-9, 20, 22] The perimeter columns bear about half of the tower’s weight, so this damage reduces its ability to bear gravity loads by about 7.5 percent. [National Institute of Standards and Technology, 9/2005, pp. 6] The actual damage to the 47 core columns is not known, as there are no photographs or videos of it, but there will be much speculation about this after 9/11. It will be suggested that some parts of the aircraft may have damaged the core even after crashing through the exterior wall. According to the National Institute of Standards and Technology (NIST): “Moving at 500 mph, an engine broke any exterior column it hit. If the engine missed the floor slab, the majority of the engine core remained intact and had enough residual momentum to sever a core column upon direct impact.” [National Institute of Standards and Technology, 9/2005, pp. 107] According to NIST’s base case computer model, three of the core columns are severed and another ten suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 189 pdf file] If this is accurate, it means that the impact damage to the core reduces the Tower’s strength by another approximately 7.5 percent, meaning that the building loses about 15 percent of its strength in total. This damage will be cited after 9/11 by NIST and others researchers as an event contributing to the building’s collapse (see October 23, 2002 and October 19, 2004). In addition, some of the fireproofing on the steel columns and trusses may be dislodged. The original fireproofing on the fire floors was mostly Blazeshield DC/F, but some of the fireproofing on the flooring has recently been upgraded to Blazeshield II, which is about 20 percent denser and 20 percent more adhesive. [National Institute of Standards & Technology, 9/2005, pp. xxxvi, 83 pdf file] Photographs and videos of the towers will not show the state of fireproofing inside the buildings, but NIST will estimate the damage to it using a computer model. Its severe case model (see (October 2002-October 2005)) will predict that 43 of the 47 core columns are stripped of their fireproofing on one or more floors and that fireproofing is stripped from trusses covering 60,000 ft2 of floor area, the equivalent of about one and a half floors. NIST will say that the loss of fireproofing is a major cause of the collapse (see April 5, 2005), but only performs 15 tests on fireproofing samples (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 23] According to NIST, more fireproofing is stripped from the South Tower (see 9:03 a.m. September 11, 2001).

Entity Tags: Mohamed Atta, National Institute of Standards and Technology, Satam Al Suqami, Waleed Alshehri, Abdulaziz Alomari, World Trade Center, Wail Alshehri

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Flight 175 hits the WTC South Tower. The picture was taken from a traffic helicopter.Flight 175 hits the WTC South Tower. The picture was taken from a traffic helicopter. [Source: WABC 7/ Salient Stills]Flight 175 hits the South Tower of the World Trade Center (Tower Two). Seismic records pinpoint the time at six seconds before 9:03 a.m. (rounded to 9:03 a.m.). Hijackers Marwan Alshehhi, Fayez Ahmed Banihammad, Mohand Alshehri, Hamza Alghamdi, and Ahmed Alghamdi presumably are killed instantly, and many more in the tower will die over the next few hours. [New York Times, 9/12/2001; CNN, 9/12/2001; CNN, 9/17/2001; North American Aerospace Defense Command, 9/18/2001; USA Today, 12/20/2001; Federal Emergency Management Agency, 5/1/2002, pp. 1-10; New York Times, 5/26/2002; Associated Press, 8/21/2002; USA Today, 9/2/2002] According to the NIST report, the crash time is 9:02:59. [National Institute of Standards and Technology, 9/2005, pp. 38] According to the 9/11 Commission Report, the crash time is 9:03:11. [9/11 Commission, 7/24/2004, pp. 8] Millions watch the crash live on television. The plane strikes the 77th through 85th floors in the 110-story building. Approximately 100 people are killed or injured in the initial impact; 600 people in the tower eventually die. The death toll is far lower than in the North Tower because about two-thirds of the South Tower’s occupants have evacuated the building in the 17 minutes since the first tower was struck. [USA Today, 12/20/2001; National Institute of Standards and Technology, 9/2005, pp. 5-9, 41] The combined death toll from the two towers is estimated at 2,819, not including the hijackers. [Associated Press, 8/21/2002] The impact severs some columns on the south side of the South Tower. Each of the Twin Towers is designed as a “tube-in-tube” structure and the steel columns which support its weight are arranged around the perimeter and in the core. The plane, which is traveling at an estimated speed of around 500 mph (see October 2002-October 2005), severs 33 of the building’s 236 perimeter columns and damages another one. [National Institute of Standards and Technology, 9/2005, pp. 39] The perimeter columns bear about half of the tower’s weight, so the damage to them reduces the tower’s ability to bear gravity loads by about 7.1 percent. [National Institute of Standards and Technology, 9/2005, pp. 6] The actual damage to the 47 core columns is not known, as there are no photographs or videos of it, but there will be much speculation about this after 9/11. It will be suggested that some parts of the aircraft may be able to damage the core even after crashing through the exterior wall (see 8:46 a.m. September 11, 2001). [National Institute of Standards and Technology, 9/2005, pp. 107] According to NIST’s base case model, five of the core columns are severed and another five suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 235 pdf file] This may reduce the tower’s ability to bear loads by a further approximately 8 percent, meaning that the aircraft impact accounted for a loss of about 15 percent of the building’s strength. This damage will be cited as an event contributing to the building’s collapse after 9/11 (see October 23, 2002 and October 19, 2004). NIST’s base case estimate of damage to the North Tower’s core will be similar, even though the aircraft impact there was dissimilar (see 8:46 a.m. September 11, 2001). Flight 11 hit the North Tower’s core head on, whereas Flight 175 only hits the corner of the South Tower’s core. [National Institute of Standards and Technology, 9/2005, pp. 20-23, 38-41] In addition, some of the fireproofing on the steel columns and trusses may be dislodged (see 8:46 a.m. September 11, 2001). [National Institute of Standards & Technology, 9/2005, pp. xxxvi, 83 pdf file] Photographs and videos of the towers will not show the state of fireproofing inside the buildings, but the National Institute of Standards and Technology (NIST) will try to estimate the damage to fireproofing using a series of computer models. Its severe case model (see (October 2002-October 2005)) will predict that 39 of the 47 core columns are stripped of their fireproofing on one or more floors and that fireproofing is stripped from trusses covering 80,000 ft2 of floor area, the equivalent of about two floors. NIST will say that the loss of fireproofing is a major cause of the collapse (see April 5, 2005), but only performs 15 tests on fireproofing samples (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 41] According to NIST, less fireproofing is stripped from the North Tower (see 8:46 a.m. September 11, 2001).

Entity Tags: World Trade Center, Marwan Alshehhi, Fayez Ahmed Banihammad, Hamza Alghamdi, National Institute of Standards and Technology, Ahmed Alghamdi, Mohand Alshehri

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Molten metal pouring out of the side of the World Trade Center.Molten metal pouring out of the side of the World Trade Center. [Source: Cameraplanet]Video footage later reveals that in the minutes immediately before the collapse of the WTC’s South Tower, a stream of molten metal starts pouring out of a window opening around the northeast corner of its 80th floor. FEMA later suggests that this is “possibly aluminum from the airliner,” and comments, “This is of particular interest because, although the building collapse appears to have initiated at this floor level, the initiation seems to have occurred at the southeast rather than the northeast corner.” [Civil Engineering, 5/2002; Federal Emergency Management Agency, 5/1/2002, pp. 2-34; Dwyer and Flynn, 2005, pp. 207] According to the National Institute of Standards and Technology, “The composition of the flowing material can only be the subject of speculation, but its behavior suggests it could have been molten aluminum.” [Pitts, Butler, and Junker, 9/2005, pp. 375] However physics professor Steven E. Jones will in 2006 dispute this, saying that molten aluminum is silvery and never turns yellow, like what is in the video footage. He will instead claim the presence of this molten metal supports the theory that explosives, specifically thermite, are what caused the Twin Towers to collapse. He says thermite can cause steel to melt and become yellowish. [Deseret Morning News, 4/10/2006]

Entity Tags: World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Numerous witnesses, including firefighters and other rescue workers, hear explosions at the start of, and during, the collapse of the south WTC tower. Some of them report hearing a single explosion:
bullet Jeff Birnbaum: “There was an explosion and the whole top leaned toward us and started coming down.” [Electrical Wholesaling, 2/1/2002]
bullet Battalion Chief John Sudnik: “[W]e heard a loud explosion or what sounded like a loud explosion and looked up and I saw Tower Two start coming down.” [City of New York, 11/7/2001]
bullet Firefighter Edward Kennedy hears “a tremendous boom, explosion… and the top of the building was coming down at us.” [City of New York, 1/17/2002]
bullet Firefighter Edward Sheehey hears “an explosion, looked up, and the building started to collapse.” [City of New York, 12/4/2001]
bullet Battalion Chief Thomas Vallebuona: “I heard ‘boom,’ an exploding sound, a real loud bang. I looked up, and I could see the Trade Center starting to come down.” [City of New York, 1/2/2002]
bullet EMT Julio Marrero: “I heard a loud bang. We looked up, and we just saw the building starting to collapse.” [City of New York, 10/25/2001]
Other witnesses report hearing multiple explosions:
bullet Journalist Pete Hamill: “We heard snapping sounds, pops, little explosions, and then the walls bulged out, and we heard a sound like an avalanche.” [New York Daily News, 9/11/2001]
bullet Police officer Sue Keane, who is an Army veteran, is located in the north WTC tower: “[I]t sounded like bombs going off. That’s when the explosions happened.… It started to get dark, then all of a sudden there was this massive explosion.” [Hagen and Carouba, 2002, pp. 65]
bullet Firefighter Keith Murphy, who is in the lobby of the North Tower: “[T]he first thing that happened, which I still think is strange to me, the lights went out.… I had heard right before the lights went out, I had heard a distant boom boom boom, sounded like three explosions.… At the time, I would have said they sounded like bombs, but it was boom boom boom and then the lights all go out.… I would say about 3, 4 seconds, all of a sudden this tremendous roar.” [City of New York, 12/5/2001]
bullet Firefighter Craig Carlsen hears “explosions coming from building two, the South Tower. It seemed like it took forever, but there were about ten explosions.… We then realized the building started to come down.” [City of New York, 1/25/2002]
bullet Firefighter Thomas Turilli, who is in the lobby of the North Tower: “[A]ll of a sudden you just heard like it almost actually that day sounded like bombs going off, like boom, boom, boom, like seven or eight, and then just a huge wind gust just came… It just seemed like a huge explosion.” [City of New York, 1/17/2002]
bullet Firefighter Stephen Viola: “[T]hat’s when the South Tower collapsed, and it sounded like a bunch of explosions. You heard like loud booms.” [City of New York, 1/10/2002]
bullet Firefighter Lance Lizzul: “[W]e heard some bangs. That made us look up, and that’s when the first Trade Center came down.” [City of New York, 12/10/2001]
bullet Paramedic Kevin Darnowski: “I heard three explosions, and then we heard like groaning and grinding, and Tower Two started to come down.” [City of New York, 11/9/2001]
However, the National Institute of Standards and Technology, which conducts a three-year study of the WTC collapses, will subsequently claim it found “no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives” (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 146]

Entity Tags: Julio Marrero, Stephen Viola, John Sudnik, Craig Carlsen, Ed Kennedy, Keith Murphy, Kevin Darnowski, Pete Hamill, Edward Sheehey, World Trade Center, Lance Lizzul, Thomas Vallebuona, Sue Keane, Jeff Birnbaum, Thomas Turilli

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Damage to the southwest corner of WTC 7.Damage to the southwest corner of WTC 7. [Source: Arquelio Galarza]World Trade Center Building 7 (WTC 7) suffers some damage, caused by debris from the collapse of the north WTC tower, according to later official reports. [Federal Emergency Management Agency, 5/1/2002, pp. 5-16; National Institute of Standards and Technology, 11/2008, pp. 16]
WTC 7 Undamaged by South Tower Collapse - WTC 7 is a 47-story office building located 370 feet north of the North Tower (WTC 1). In the final report of its investigation into WTC 7’s collapse, published in November 2008 (see November 20, 2008), the National Institute of Standards and Technology (NIST) will state that although a few windows on the lower floors of WTC 7’s south face were broken when the South Tower (WTC 2) collapsed at 9:59 a.m. (see 9:59 a.m. September 11, 2001), “None of the large pieces of debris from WTC 2 hit WTC 7, because of the large distance between the two buildings,” and there is “no evidence of structural damage to WTC 7” as a result of the South Tower’s collapse.
Debris Reportedly Damages Exterior Columns - However, when the North Tower collapses (see 10:28 a.m. September 11, 2001), some fragments of debris are “forcibly ejected” from it, and travel “distances up to hundreds of meters.” According to NIST, pieces of this debris “hit WTC 7, severing six columns on floors 7 through 17 on the south face and one column on the west face near the southwest corner.” NIST will add that the debris also causes “structural damage between floor 44 and the roof,” and breaks a large number of windows on WTC 7’s south face.
Building Core Undamaged - However, NIST will state, based on “photographic evidence, witness accounts, and engineering judgment, it is likely that the structural damage (steel and floor slabs) did not penetrate beyond the perimeter of the building core. At the southwest corner, the structural damage extended only about one-third of the distance from the exterior wall to the building core.” NIST will comment, “Compared to the airplane impact damage to the WTC towers, there was relatively little damage to the interior of WTC 7.” There is also “no superficial or structural damage” to WTC 7’s north and east faces. And the sprayed fire resistive material that has been applied to the building’s steel columns, girders, and beams is only damaged in the “immediate vicinity of the WTC 1 debris impact.” NIST will admit, however, that there are “uncertainties” in its accounting of the events leading up to the collapse of WTC 7, because “the remains of all the WTC buildings were disposed of before Congressional action and funding was available for [its] investigation [of the WTC collapses] to begin” (see Shortly After September 11, 2001 and September 12-October 2001). [National Institute of Standards and Technology, 8/21/2008; National Institute of Standards and Technology, 11/2008, pp. 15-16]
FEMA Describes WTC 7 Damage - According to an earlier report on the collapse of WTC 7, published by the Federal Emergency Management Agency (FEMA) in May 2002 (see May 1, 2002), at that time, the “extent and severity of the resulting damage to WTC 7” when the North Tower collapses “are currently unknown.” But based on “photographic evidence and eyewitness accounts,” it is “assumed that the south side of the building was damaged to some degree.” FEMA’s report will state: “It does not appear that the collapse of WTC 1 affected the roof, or the east, west, and north elevations of WTC 7 in any significant way. However, there was damage to the southwest corner of WTC 7 at approximately floors 8 to 20, 24, 25, and 39 to 46.” The report will add: “According to firefighters’ eyewitness accounts from outside of the building, approximately floors 8-18 were damaged to some degree. Other eyewitness accounts relate that there was additional damage to the south elevation.” [Federal Emergency Management Agency, 5/1/2002, pp. 5-16, 5-20]
Structural Damage Not Responsible for Collapse - WTC 7 will collapse at 5:20 p.m. this afternoon (see (5:20 p.m.) September 11, 2001). [National Institute of Standards and Technology, 8/21/2008] However, NIST will conclude that the structural damage the building suffers plays no role in causing it to come down. NIST will state, “Other than initiating the fires in WTC 7, the damage from the debris from WTC 1 had little effect on initiating the collapse of WTC 7.” [National Institute of Standards and Technology, 11/2008, pp. xxxvii] WTC 7 suffers fires on some floors, which are reportedly initiated by debris from the collapse of the North Tower (see (10:28 a.m.-5:20 p.m.) September 11, 2001). According to NIST, it is these fires, “rather than the structural damage that resulted from the impacts” of debris, which “initiated the building’s collapse.” [National Institute of Standards and Technology, 8/21/2008]

Entity Tags: World Trade Center, National Institute of Standards and Technology, Federal Emergency Management Agency

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

A four-image progression of photos showing World Trade Center Building 7 collapsing down into its footprint.A four-image progression of photos showing World Trade Center Building 7 collapsing down into its footprint. [Source: unknown] (click image to enlarge)Building 7 of the World Trade Center complex, a 47-story tower, collapses. No one is killed. [CNN, 9/12/2001; Washington Post, 9/12/2001; MSNBC, 9/22/2001; Associated Press, 8/21/2002] It collapses in 6.6 seconds, which is just 0.6 of a second longer than it would have taken a free-falling object dropped from its roof to hit the ground. [Deseret Morning News, 11/10/2005] Many questions will arise over the cause of its collapse in the coming months and years. Building 7, which was not hit by an airplane, is the first modern, steel-reinforced high-rise to collapse because of fire. [Chicago Tribune, 11/29/2001; Stanford Report, 12/5/2001; New York Times, 3/2/2002] Some will later suggest that the diesel fuel stored in several tanks on the premises may have contributed to the building’s collapse. The building contained a 6,000-gallon tank between its first and second floors and another four tanks, holding as much as 36,000 gallons, below ground level. There were also three smaller tanks on higher floors. [Chicago Tribune, 11/29/2001; New York Times, 3/2/2002; New York Observer, 3/25/2002; Federal Emergency Management Agency, 5/1/2002, pp. 1-17] However, the cause of the collapse is uncertain. A 2002 government report will conclude: “The specifics of the fires in WTC 7 and how they caused the building to collapse remain unknown at this time. Although the total diesel fuel on the premises contained massive potential energy, the best hypothesis has only a low probability of occurrence.” [Federal Emergency Management Agency, 5/1/2002, pp. 1-17] Some reports indicate that the building may have been deliberately destroyed. Shortly after the collapse, CBS News anchor Dan Rather comments that the collapse is “reminiscent of… when a building was deliberately destroyed by well-placed dynamite to knock it down.” [CBS News, 9/11/2001] And moments after the collapse, MSNBC’s Brian Williams joins David Restuccio, an FDNY lieutenant, by phone to ask him about the collapse. “You guys knew this was coming all day?” asks Williams. Restuccio replies: “We had heard reports that the building was unstable, and that it would eventually need to come down on its own, or it would be taken down. I would imagine it came down on its own.” Restuccio does not explain what he means by “it would be taken down.” [MSNBC, 9/11/2001]

Entity Tags: Dan Rather, World Trade Center, David Restuccio

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Michael Burton.Michael Burton. [Source: PBS]Following the World Trade Center collapses, a decision is made to quickly transport the remaining structural steel to scrap yards, to be shipped abroad and melted down for reuse. Consequently, virtually all of it is disposed of before investigators trying to assess why the WTC collapsed can examine it. Michael Burton and other officials at the Department of Design and Construction—the New York City agency overseeing the cleanup operation (see (September 11, 2001-May 2002))—are responsible for making this decision. Burton clears it with Richard Tomasetti of Thornton-Tomasetti Engineers, the prime consultant on the cleanup job. However, referring to the subsequent WTC investigation by the National Institute of Standards and Technology (see August 21, 2002), Tomasetti will later admit that had he known the direction that investigations into the collapses would take, he would have taken a different stand. [Langewiesche, 2002, pp. 30; Glanz and Lipton, 2004, pp. 330 and 396] Authors and New York Times reporters James Glanz and Eric Lipton write that Michael Burton, “who had become the effective czar for the cleanup job, had made it clear that he cared very little about engineering subtleties like the question of why the towers first stood, then collapsed on September 11. ‘We know why they fell,’ he said. ‘Because they flew two planes into the towers.’ But he was deeply immersed in the details of hauling steel out of the debris pile.” [Glanz and Lipton, 2004, pp. 299] Much of the WTC steel will be shipped to India, China, and other Asian countries for recycling (see September 12-October 2001).

Entity Tags: New York City Department of Design and Construction, World Trade Center, Michael Burton, Richard Tomasetti

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The New York Times reports that “some of the nation’s leading structural engineers and fire-safety experts” believe the investigation into the collapse of the WTC is “inadequate” and “are calling for a new, independent and better-financed inquiry that could produce the kinds of conclusions vital for skyscrapers and future buildings nationwide.” Experts critical of the investigation include “some of those people who are actually conducting it.” They point out that the current team of 20 or so investigators has no subpoena power, inadequate financial support, and little staff support. Additionally, it has been prevented from interviewing witnesses and frequently prevented from examining the disaster site, and has even been unable to obtain basic information like detailed blueprints of the buildings that collapsed. The decision to recycle the steel columns, beams, and trusses from the WTC rapidly in the days immediately after 9/11 means definitive answers may never be known. [New York Times, 12/25/2001] Incredibly, some of the steel is reforged into commemorative medallions selling for $30 apiece. [Associated Press, 1/30/2002]

Entity Tags: World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

A firefighter trade magazine with ties to the New York Fire Department calls the investigation into the collapse of the WTC a “half-baked farce.” The article points out that the probe has not looked at all aspects of the disaster and has had limited access to documents and other evidence. “The destruction and removal of evidence must stop immediately.” The writer, Bill Manning, states, “I have combed through our national standard for fire investigation, NFPA 921, but nowhere in it does one find an exemption allowing the destruction of evidence for buildings over 10 stories tall.” He concludes that a growing number of fire protection engineers have theorized that “the structural damage from the planes and the explosive ignition of jet fuel in themselves were not enough to bring down the towers.” Yet, “[a]s things now stand and if they continue in such fashion, the investigation into the World Trade Center fire and collapse will amount to paper- and computer-generated hypotheticals.” [Fire Engineering, 1/2002; New York Daily News, 1/4/2002]

Entity Tags: New York City Fire Department, World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

A structural engineer who was a member of the team assembled by the American Society of Civil Engineers to investigate the World Trade Center site after 9/11 complains about the decision to rapidly destroy the remaining structural steel from the collapsed WTC buildings. Dr. Abolhassan Astaneh-Asl is a professor of civil and environmental engineering at the University of California at Berkeley, and specializes in studying structural damage done by earthquakes and terrorist bombings. [Chronicle of Higher Education, 12/7/2001; CBS News, 3/11/2002; Associated Press, 9/6/2002] He had come to New York a week after 9/11 to examine the collapsed towers, hoping to gain an understanding of how they had come down (see September 19-October 2001). [New York Times, 10/2/2001; US Congress. House. Committee on Science, 3/6/2002] However, New York City officials had decided early on to quickly transport the remaining structural steel to scrap yards, to be shipped abroad and melted down for reuse (see Shortly After September 11, 2001). As CBS News now reports, “As a result, Astaneh has almost certainly missed seeing crucial pieces before they were cut up and sent overseas.” Astaneh-Asl complains: “When there is a car accident and two people are killed, you keep the car until the trial is over. If a plane crashes, not only do you keep the plane, but you assemble all the pieces, take it to a hangar, and put it together. That’s only for 200, 300 people, when they die. In this case you had 3,000 people dead.” He says: “My wish was that we had spent whatever it takes, maybe $50 million, $100 million, and maybe two years, get all this steel, carry it to a lot. Instead of recycling it, put it horizontally, and assemble it. You have maybe 200 engineers, not just myself running around trying to figure out what’s going on. After all, this is a crime scene and you have to figure out exactly what happened for this crime, and learn from it.” However, he adds, “My wish is not what happens.” [CBS News, 3/12/2002] Astaneh-Asl previously told the New York Times that the scrap steel from the WTC was “worth only a few million dollars, a tiny fraction of the billions of dollars the cleanup will cost.” Yet the knowledge that could be gained from it “could save lives in a future disaster.” [New York Times, 10/2/2001]

Entity Tags: World Trade Center, Abolhassan Astaneh-Asl

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST)—an agency of the US Commerce Department’s Technology Administration—announces details of its forthcoming investigation into the collapses of the World Trade Center Twin Towers and Building 7 on 9/11. The NIST investigation aims “to investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the World Trade Center (WTC) disaster.” It also aims to examine the activities of building occupants and emergency responders on 9/11, studying such issues as emergency communications within the WTC, the movement of people during the evacuations, and issues around persons with disabilities. Leading technical experts from industry, academia, and other laboratories, alongside NIST’s own expert staff, will participate in the investigation. Expert professionals from the private sector will also be involved. Glenn Corbett, a fire science professor at John Jay College, says, “This is going to be the most extensive building disaster investigation ever performed.” [Associated Press, 8/21/2002; National Institute of Standards and Technology, 8/21/2002; National Institute of Standards and Technology, 8/3/2005] The investigation is formally authorized in October 2002, when the National Construction Safety Team Act is signed into law. The act, which gives NIST authorization to investigate major building failures in the US, is written largely as a result of the World Trade Center collapses. [National Institute of Standards and Technology, 10/2/2002; New York Times, 5/8/2003] NIST’s investigation is originally proposed to last two years, with a budget of $16 million. [National Institute of Standards and Technology, 8/21/2002] However, it eventually will last three years, with its final report into the collapses of the Twin Towers being released in October 2005 (see October 26, 2005). A previous analysis of the WTC collapses conducted by FEMA and the American Society of Civil Engineers (ASCE) was completed earlier in 2002 (see May 1, 2002), but this had a budget of just $1.1 million. By the time NIST starts its investigation, much of the crucial steel debris from the WTC collapses has already been destroyed (see September 12-October 2001). They later refer to there being a “scarcity of physical evidence that is typically available in place for reconstruction of a disaster.” [National Institute of Standards and Technology, 9/2005, pp. xxxvi]

Entity Tags: World Trade Center, National Institute of Standards and Technology, Glenn Corbett

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

During the course of its three-year investigation of the World Trade Center collapses, the National Institute of Standards and Technology (NIST) performs computer simulations of the behavior of each WTC tower on 9/11. In its final report, released in October 2005 (see October 26, 2005), it will describe having determined which variables most affected the outcome of its various simulations. Then, “[f]or each of the most influential variables, a central or middle value and reasonable high and low values were identified.” However, “[u]pon a preliminary examination of the middle cases, it became clear that the towers would likely remain standing. The less severe cases were discarded after the aircraft impact results were compared to observed events. The middle cases… were discarded after the structural response analysis of major subsystems were compared to observed events.” Therefore, the “more severe case… was used for the global analysis of each tower.” But, to “the extent that the simulations deviated from the photographic evidence or eyewitness reports, the investigators adjusted the input, but only within the range of physical reality.” [National Institute of Standards and Technology, 9/2005, pp. 143-144]

Entity Tags: National Institute of Standards and Technology, World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST) issues a progress report on its investigation into the World Trade Center collapses. Since 2002, NIST has been investigating the collapses of the Twin Towers and WTC Building 7 (see August 21, 2002). The progress report includes its “working hypothesis” for the collapse of WTC 7. This was a 47-story building, located about 350 feet from the north side of WTC 1, which collapsed completely at around 5:20 in the afternoon of 9/11. The report claims that “fire appears to have played a key role” in the collapse, though it points out, “No fire was observed or reported in the afternoon on floors 1-5, 10, or above Floor 13.” It also says, “there may have been some physical damage on the south side of the building.” NIST summarizes its working hypothesis of the WTC 7 collapse as follows:
bullet “An initial local failure at the lower floors (below Floor 13) of the building due to fire and/or debris induced structural damage of a critical column (the initiating event), which supported a large span floor bay with an area of about 2,000 square feet.”
bullet “Vertical progression of the initial local failure up to the east penthouse, as large floor bays were unable to redistribute the loads, bringing down the interior structure below the east penthouse.”
bullet “Horizontal progression of the failure across the lower floors… triggered by damage due to the vertical failure, resulting in the disproportionate collapse of the entire structure.”
NIST claims this hypothesis “is consistent with all evidence currently held by NIST, including photographs and videos, eyewitness accounts and emergency communication records,” but says it “will be revised and updated as results of ongoing, more comprehensive analyses become available.” [National Institute of Standards and Technology, 6/2004, pp. L1, L3, L17, L34, L38, L51-L52; National Institute of Standards and Technology, 6/18/2004] NIST will release its final reports on the collapses of the Twin Towers in October 2005 (see October 26, 2005). As of mid-2007, it has yet to release a final report on the collapse of WTC 7. In early 2006, Dr. S. Shyam Sunder, who is the lead investigator for NIST’s WTC investigation, will admit, “truthfully, I don’t really know” what caused WTC 7 to collapse. He will add, “We’ve had trouble getting a handle on building no. 7” (see March 20, 2006). [New York Magazine, 3/20/2006] An earlier report on the WTC collapses, released by the Federal Emergency Management Agency (FEMA) in May 2002, had been inconclusive on what caused WTC 7 to collapse, and stated that “Further research, investigation, and analyses” were necessary (see May 1, 2002). [Federal Emergency Management Agency, 5/1/2002, pp. 5-31]

Entity Tags: World Trade Center, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Shyam Sunder.Shyam Sunder. [Source: NIST]The National Institute of Standards and Technology (NIST) releases nearly 500 pages of documents, detailing the latest findings of its investigation of the WTC collapses on 9/11. These include its hypotheses for the collapse sequences of each of the Twin Towers; details of their analysis of interviews with nearly 1,200 building occupants, emergency responders, and victims’ relatives; and information from their analysis of the emergency response and evacuation procedures. Their investigation into the collapses is based upon an analysis of thousands of photos and videos, examination of many of the elements used to construct the towers, and computer-enhanced modeling of the plane impacts and the spreading of the fires. Their hypothesis is that the towers collapsed ultimately due to the fires they suffered: As the fires burned, the buildings’ steel core columns buckled and shortened. This shifted more load to the buildings’ perimeter columns, which were already affected by the heat of the fires, and caused them to give way under the increased stress. Investigators have conducted a test with a reconstructed section of the WTC floor, and found that the original fireproofing was sufficient to meet the New York City building code. They say that had a typical office fire occurred in the towers, without the structural damage and the loss of some fireproofing caused by the plane impacts, it is likely the buildings would have remained standing. Lead investigator Dr. Shyam Sunder says, “The buildings performed as they should have in the airplane impact and extreme fires to which they were subjected. There is nothing there that stands out as abnormal.” NIST’s theories of why the WTC buildings collapsed conflict with an earlier investigation by FEMA, which claimed the collapse of the North Tower had begun in its core, rather than its perimeter columns (see May 1, 2002). [National Institute of Standards and Technology, 10/19/2004; New York Times, 10/20/2004]

Entity Tags: Shyam Sunder, National Institute of Standards and Technology, World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Based upon its three-year investigation of the WTC collapses, the National Institute of Standards and Technology (NIST) calls for changes in the planning, construction, and operation of skyscrapers. NIST releases 43 draft reports, totaling about 10,000 pages, for public comments. These include 25 pages of recommendations, intended to learn from 9/11 and make building occupants and emergency responders safer in any future disasters. NIST’s inquiry has been conducted by more than 200 technical experts and contractors, and had two main parts: to look at the causes of the collapses and to identify weaknesses in building codes. Their recommendations include specific improvements to building standards, codes and practices; changes to evacuation and emergency response procedures; and research to help prevent future building failures. NIST does not have the authority to change building codes, but hopes to influence the policies of local authorities. The cost of implementing their recommended changes would add an estimated extra 2 to 5 percent to the development costs of buildings. Some are critical of their recommendations. Structural engineer Jon Magnusson, whose firm is the descendant of the company that designed the Twin Towers, says, “They are leading the public down the wrong path. They are saying we are going to fix the codes in order to deal with Sept. 11th. The physics say that you can’t do that.” [New York Times, 6/22/2005; National Institute of Standards and Technology, 6/23/2005; Associated Press, 6/24/2005] The New York Times points out that between 1989 and 1999, only five civilians had been killed in some 6,900 reported high-rise office building fires within the US. [New York Times, 6/24/2005] NIST will release its final report on the Twin Towers collapses four months later (see October 26, 2005).

Entity Tags: National Institute of Standards and Technology, World Trade Center, Jon Magnusson

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The 43 NIST reports ran to over 10,000 pages.The 43 NIST reports ran to over 10,000 pages. [Source: NIST]The National Institute of Standards and Technology (NIST) issues the final report of its three-year, $16 million study into the WTC collapses on 9/11. NIST has produced over 10,000 pages of findings, and its report includes 30 recommendations for improving building safety, such as having wider stairwells and structurally hardened elevators for use in emergencies. The recommendations are mostly the same as those outlined in an earlier draft of the report (see June 23, 2005). [Engineering News-Record, 10/27/2005; New York Times, 10/27/2005] NIST has made some amendments and clarifications, though, based upon nearly 500 comments received during a six-week public review period. [National Institute of Standards and Technology, 10/26/2005] NIST’s theory about what caused the Twin Towers to collapse remains the same as that described in its previously released findings (see October 19, 2004). However, the NIST’s account only examines events up to the initiation of each collapse; the investigation “does not actually include the structural behavior of the tower after the conditions for collapse initiation were reached and collapse became inevitable.” [National Institute of Standards and Technology, 9/2005, pp. 82] NIST makes no mention of molten metal found at the collapse site in the weeks and months after 9/11, which has been described in numerous reports (see September 12, 2001-February 2002). The “NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to September 11, 2001.” [National Institute of Standards and Technology, 9/2005, pp. 146] Members of Congress are critical of NIST’s recommendations, saying they are not detailed enough, or adequately documented, to be rapidly incorporated into standard building code publications. [New York Times, 10/27/2005] According to Glenn Corbett, a technical adviser to NIST and fire science professor at John Jay College, NIST is not aggressive enough to carry out major forensic investigations. He says, “Instead of a gumshoe inquiry that left no stone unturned, I believe the investigations were treated more like research projects in which they waited for information to flow to them.” [Associated Press, 10/26/2005; US Congress, 10/26/2005 pdf file] NIST will release its final report on the collapse of Building 7 of the WTC separately, at a later date. [National Institute of Standards and Technology, 9/2005, pp. xiii]

Entity Tags: World Trade Center, Glenn Corbett, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

A poll by Ohio University and Scripps Howard News Service finds that a significant minority of Americans believe there was US government complicity in the 9/11 attacks. Thirty-six percent of the 1,010 respondents say they believe that US government officials “either assisted in the 9/11 attacks or took no action to stop the attacks because they wanted the United States to go to war in the Middle East.” Sixteen percent believe that secretly planted explosives brought down the Twin Towers, and 12 percent believe a military cruise missile, rather than a hijacked aircraft, hit the Pentagon. [Scripps Howard News Service, 8/3/2006; San Francisco Chronicle, 9/3/2006] An earlier poll had found that half of New York City residents believed government officials knew in advance of the attacks and consciously failed to act (see August 30, 2004).

Entity Tags: Ohio University, Scripps Howard News Service

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

One of the ‘puffs of smoke’ observed during the Twin Towers collapses.One of the ‘puffs of smoke’ observed during the Twin Towers collapses. [Source: Richard Lethin]The National Institute of Standards and Technology (NIST) issues a seven-page fact sheet to counter alternative theories about the WTC collapses. NIST conducted a three-year study of the collapses, and concluded they were caused by the damage when the planes hit combined with the effects of the ensuing fires. However, many people—what the New York Times calls an “angry minority”—believe there was US government complicity in 9/11, and a recent poll (see July 6-24, 2006) found 16 percent of Americans believe the WTC towers were brought down with explosives. [National Institute of Standards and Technology, 8/31/2006; New York Times, 9/2/2006; Reuters, 9/2/2006] The fact sheet responds to 14 “Frequently Asked Questions.” Some of its key points include the following:
bullet Regarding whether NIST considered a controlled demolition hypothesis: “NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down… using explosives… Instead, photographs and videos from several angles clearly show that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward until the dust clouds obscured the view.” However, it admits, “NIST did not test for the residue” of explosives in the remaining steel from the towers.
bullet Its explanation for puffs of smoke seen coming from each tower as it collapsed: “[T]he falling mass of the building compressed the air ahead of it—much like the action of a piston—forcing smoke and debris out the windows as the stories below failed sequentially.”
bullet Its explanation for a stream of yellow molten metal that poured down the side of the South Tower shortly before it collapsed (see (9:50 a.m.) September 11, 2001). NIST previously claimed it was aluminum, but this should not have been yellow in color: “Pure liquid aluminum would be expected to appear silvery. However, the molten metal was very likely mixed with large amounts of hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions and computers) which can display an orange glow.”
bullet Regarding reports of molten steel in the wreckage at Ground Zero (see September 12, 2001-February 2002): “Any molten steel in the wreckage was more likely due to the high temperature resulting from long exposure to combustion within the pile than to short exposure to fires or explosions while the buildings were standing.”
bullet Regarding the collapse of WTC 7 (see (5:20 p.m.) September 11, 2001): “While NIST has found no evidence of a blast or controlled demolition event, NIST would like to determine the magnitude of hypothetical blast scenarios that could have led to the structural failure of one or more critical elements.” [National Institute of Standards and Technology, 8/30/2006] In response to the fact sheet, Kevin Ryan, the coeditor of the online Journal of 9/11 Studies, says, “The list of answers NIST has provided is generating more questions, and more skepticism, than ever before.” He says, “NIST is a group of government scientists whose leaders are Bush appointees, and therefore their report is not likely to veer from the political story.” [New York Times, 9/2/2006; Reuters, 9/2/2006]

Entity Tags: National Institute of Standards and Technology, Kevin Ryan

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

In a reply to criticisms of its World Trade Center investigation, the National Institute of Standards and Technology (NIST) admits that it is unable to fully explain the total collapse of the Twin Towers on 9/11. NIST’s letter is a response to a “request for correction” letter sent to it five months earlier by Bob McIlvaine and Bill Doyle, who both lost family members on 9/11, along with scientists Kevin Ryan and Steven E. Jones, architect Richard Gage, and the group Scholars for 9/11 Truth and Justice. This letter made several assertions about NIST’s final reports of its WTC investigation, and suggested they had violated the Data Quality Act and NIST’s information quality standards. NIST’s reply denies the requests for corrections. However, it also mentions, “[W]e are unable to provide a full explanation of the total collapse” of the World Trade Center. [National Institute of Standards and Technology, 9/27/2007 pdf file] In its final report on the Twin Towers collapses, released in October 2005, NIST admitted that its investigation did “not actually include the structural behavior of the tower after the conditions for collapse initiation were reached and collapse became inevitable” (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 82]

Entity Tags: National Institute of Standards and Technology, World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST) publishes a fact sheet responding to 14 “frequently asked questions” about its investigation into the collapse of the Twin Towers on September 11. Some of the key questions and answers are as follows:
bullet Regarding the question, “Why was the collapse of WTC 1 and 2 not arrested by the intact structure below the floors where columns first began to buckle?” NIST replies, “The vertical capacity of the connections supporting an intact floor below the level of collapse was adequate to carry the load of 11 additional floors if the load was applied gradually and 6 additional floors if the load was applied suddenly (as was the case).” As the number of floors above the points where the collapses initiated exceeded six (12 in the case of the North Tower, 29 for the South), NIST says, “[T]he floors below the level of collapse initiation were unable to resist the suddenly applied gravitational load from the upper floors of the buildings.”
bullet In answer to the question of “Why was physical evidence not collected immediately following the collapse of the WTC towers,” NIST says, “In the initial days and weeks following the WTC disaster, the emphasis was on rescue and later on recovery, necessitating the removal of steel and disturbing the collapse site.” It adds, “NIST did not receive the legal authority to collect and preserve physical evidence from a disaster/failure site until the National Construction Safety Team Act became law in October 2002.” The decision to rapidly scrap the remaining steel from the WTC was made shortly after 9/11 (see Shortly After September 11, 2001), but the destruction of this steel was strongly protested by some within the engineering and firefighting communities (see December 25, 2001 and January 4, 2002).
bullet In response to a question about why it did not use its subpoena authority during its investigation, NIST states that its “experience during the investigation was that it was able to obtain all essential documentary and visual evidence without the need to invoke subpoena authority.”
bullet In answer to the question, “Why didn’t NIST fully model the collapse initiation and propagation of WTC towers?” NIST says, “Once the collapse had begun, the propagation of the collapse was readily explained without the same complexity of modeling” as was used to determine the sequence of events leading up to the collapse initiation.
bullet During its investigation, NIST had selected several variables for its computer simulations, and then experimented with different possible values (see (October 2002-October 2005)). But it has been asked: “Why didn’t NIST consider the ‘base’ and ‘less severe’ cases throughout its analysis of the WTC towers? What was the technical basis for selecting only the ‘more severe’ case for its analyses?” Its answer is that, “Of the three [possible values], the more severe case resulted in the closest agreement with the visual and physical evidence.” [National Institute of Standards and Technology, 12/14/2007]
NIST published its final report on the Twin Towers collapse in October 2005 (see October 26, 2005). It released an earlier fact sheet answering previous “frequently asked questions” in August 2006 (see August 30, 2006). [National Institute of Standards and Technology, 8/30/2006]

Entity Tags: National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

After the National Institute of Standards and Technology (NIST) announces the results of its investigation into the collapse of World Trade Center Building 7, some critics dispute its explanation for the collapse and question its apparent debunking of claims that explosives were used to demolish the building. The 47-story tower collapsed late in the afternoon of 9/11, even though no plane hit it (see (5:20 p.m.) September 11, 2001). Some have argued that fire and the falling debris from the Twin Towers’ collapses should not have brought down such a large steel and concrete structure. [Associated Press, 8/21/2008]
NIST Lacks 'the Expertise on Explosives' - James Quintiere, a professor of fire protection engineering at the University of Maryland who previously worked as the chief of NIST’s fire science and engineering division, says that NIST does not “have the expertise on explosives, so I don’t know how they came to that conclusion,” that explosives did not cause the collapse. However, Quintiere says he never personally believed explosives were involved. [Los Angeles Times, 8/22/2008] Richard Gage, a California architect and leader of a group called Architects and Engineers for 9/11 Truth, complains, “How much longer do we have to endure the cover-up of how Building 7 was destroyed?” The New York Times points out that “the collapse of 7 World Trade Center—home at the time to branch offices of the Central Intelligence Agency, the Secret Service, and the Giuliani administration’s emergency operations center—is cited in hundreds of Web sites and books as perhaps the most compelling evidence that an insider secretly planted explosives, intentionally destroying the tower.” [New York Times, 8/21/2008]
NIST Presentation - At a presentation of its findings earlier in the day, NIST announced that, in its three-year study of the collapse, it found no evidence showing explosives were used to bring the building down. [National Institute of Standards and Technology, 8/21/2008; National Institute of Standards and Technology, 8/21/2008] During his summary of the findings of NIST’s WTC 7 investigation (see August 21, 2008), lead investigator Shyam Sunder said, “We did not find any evidence that explosives were used to bring the building down.” [National Institute of Standards and Technology, 8/21/2008]
'No Witness Reports' of Loud Explosions - In the draft version of its final report on the collapse, which is released on this day (see August 21, 2008), NIST explains: “Blast from the smallest charge capable of failing a critical column… would have resulted in a sound level of 130 dB to 140 dB at a distance of at least half a mile if unobstructed by surrounding buildings.… This sound level is consistent with standing next to a jet plane engine and more than ten times louder than being in front of the speakers at a rock concert. There were no witness reports of such a loud noise, nor was such a noise heard on the audio tracks of video recordings of the WTC 7 collapse.” [National Institute of Standards and Technology, 8/2008, pp. 44-45 pdf file]
NIST Rules out Thermite - Skeptics have argued that an incendiary material called thermite was used to bring down WTC 7 (see August 4, 2008), and this would not necessarily have created such a loud explosive boom. [New York Times, 8/21/2008] But in a fact sheet published on this day, NIST responds: “To apply thermite to a large steel column, approximately 0.13 lb of thermite would be needed to heat and melt each pound of steel. For a steel column that weighs approximately 1,000 lbs. per foot, at least 100 lbs. of thermite would need to be placed around the column, ignited, and remain in contact with the vertical steel surface as the thermite reaction took place. This is for one column… presumably, more than one column would have been prepared with thermite, if this approach were to be used. It is unlikely that 100 lbs. of thermite, or more, could have been carried into WTC 7 and placed around columns without being detected, either prior to Sept. 11 or during that day.” [National Institute of Standards and Technology, 8/21/2008] Sunder says that investigators therefore decided not to use their computer model to evaluate whether a thermite-fueled fire might have brought down WTC 7. Pointing to the omission, one skeptic says, “It is very difficult to find what you are not looking for.” [New York Times, 8/21/2008] In a 2006 fact sheet, NIST in fact admitted it “did not test for the residue” of explosives or thermite in the remaining structural steel from the WTC collapses (see August 30, 2006). [National Institute of Standards and Technology, 8/30/2006] And, as the New York Times notes, “Adding to the suspicion is the fact that in the rush to clean up the site, almost all of the steel remains of the tower were disposed of, leaving investigators in later years with little forensic evidence” (see Shortly After September 11, 2001 and September 12-October 2001). [New York Times, 8/21/2008]
Extensive Preparations for Demolition - NIST’s new fact sheet also points out: “For [WTC 7] to have been prepared for intentional demolition, walls and/or column enclosures and fireproofing would have to be removed and replaced without being detected. Preparing a column includes steps such as cutting sections with torches, which produces noxious and odorous fumes. Intentional demolition usually requires applying explosive charges to most, if not all, interior columns, not just one or a limited set of columns in a building.” [National Institute of Standards and Technology, 8/21/2008]

Entity Tags: Richard Gage, National Institute of Standards and Technology, Shyam Sunder, World Trade Center, James Quintiere

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

NIST’s ‘Final Report on the Collapse of World Trade Center Building 7.’NIST’s ‘Final Report on the Collapse of World Trade Center Building 7.’ [Source: National Institute of Standards and Technology.]The National Institute of Standards and Technology (NIST) releases the final report of its three-year investigation of the collapse of World Trade Center Building 7, the 47-story skyscraper which collapsed late in the afternoon of 9/11 (see (5:20 p.m.) September 11, 2001). This is the completed version of the report, and comes three months after a draft version was released for public comment (see August 21, 2008). NIST states that the new report “is strengthened by clarifications and supplemental text suggested by organizations and individuals worldwide in response to the draft WTC 7 report.” NIST conducted an additional computer analysis in response to comments from the building community, and made several minor amendments to the report. But, it says, “the revisions did not alter the investigation team’s major findings and recommendations, which include identification of fire as the primary cause for the building’s failure.” With the release of this report, NIST has completed its six-year investigation of the World Trade Center collapses, which it commenced in August 2002 (see August 21, 2002). The final report of its investigation of the Twin Towers’ collapses was published in October 2005 (see October 26, 2005). [National Institute of Standards and Technology, 11/20/2008; Occupational Health and Safety, 11/25/2008]

Entity Tags: World Trade Center, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

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