WTC7
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[edit] Introduction
[edit] The building
WTC7 was a 47-story building, designed by Emery Roth & Sons, with a red granite façade. The building was 610 feet (186 m) tall, with a trapezoidal footprint that was 330 ft (101 m) long and 140 ft (43 m) wide.[1].
The building was constructed above a Con Edison substation that had been on the site since 1967. The substation had a caisson foundation designed to carry the weight of a future building of 25 stories containing 600,000 sq ft (55,700 m²). The final design for 7 World Trade Center was for a much larger building covering a larger footprint than originally planned when the substation was built.[2]
The structural design of 7 World Trade Center included features to allow a larger building than originally planned to be constructed. A system of gravity column transfer trusses and girders was located between floors 5 and 7 to transfer loads to the smaller foundation. Existing caissons installed in 1967 were used, along with new ones, to accommodate the building. The fifth floor functioned as a structural diaphragm, providing lateral stability and distribution of loads between the new and old caissons. Above the seventh floor, the building's structure was a typical tube-frame design, with columns in the core and on the perimeter, and lateral loads resisted by perimeter moment frames.[3]
The spray-on fireproofing for structural steel elements was gypsum-based Monokote which had a two-hour fire rating for steel beams, girders and truss, and a three-hour rating for columns.[4]
Mechanical equipment was installed on floors four through seven, including 12 transformers on the fifth floor. Several generators in the building were used by the Office of Emergency Management, Salomon Smith Barney and others.[5] Storage tanks contained 24,000 gallons (91,000 L) of diesel fuel to supply the generators. Fuel oil distribution components were located at ground level, up to the ninth floor. The roof of the building included a small west penthouse and a larger east mechanical penthouse.[6]
[edit] The damage
According to eyewitness accounts and photographs, the damage to the south face was extensive and severe:
- I remember standing there looking over at building 7 and realizing that a big chunk of the lower floors had been taken out on the Vesey Street [south] side. (Deputy Chief Nick Visconti[7])
- There was a huge gaping hole and it [the fire] was scattered throughout there. It was a huge hole. I would say it was probably about a third of it, right in the middle of it. (Captain Chris Boyle'[8])
[edit] The fire
Besides the structural damage, WTC7 also caught fire. It is possible to track the progress of the fires in WTC7 by reference to eyewitness reports. According to Deputy Chief Peter Hayden, asked "Was there heavy fire in there right away?":
- No, not right away, and that's probably why it stood for so long because it took a while for that fire to develop.[9]
This is consistent with early reports of "a couple of floors burning"[10]. By the time the order was given to evacuate the area, Chief of Department Daniel Nigro says that there was "very heavy fire on many floors"[11]. By half-an-hour before the collapse, the building is described as "fully involved in flames":
- Just when you thought it was over, you’re walking by this building and you’re hearing this building creak and fully involved in flames ... Sure enough, about half an hour later it came down. (Lieutenant James McGlynn [12])
- In the case of WTC 7, the estimated combusted fuel load was similar to the 4 lb/ft2 estimated in the towers. The initial fires were small enough that most were not visible at the windows for several hours. Most likely, these early fires involved only a small number of workstations at a time. The early fires raised the air temperatures, preheating other clusters of cubicles and leading to the larger fires seen during the afternoon.'
- Once the fires had begun heating the air, the overall air temperatures on a floor continued to rise as new combustible material became involved. The local air temperatures began to fall when the local fuel supply was depleted and fresh air reached that area. The heating of the structure through its protective insulation was a result of both the high air temperatures that were reached and the duration of those high air temperatures, not just the duration of local burning.[13]
[edit] Firefighters expected the collapse
A number of accounts of 9/11 show that firefighters expected the collapse of WTC7, on account of the extent of the damage and fire, the bulging of the structure, and the ominous creaking noises coming from the building. The following are merely among the most telling quotes:
- Then we received an order from Fellini, we're going to make a move on 7. That was the first time really my stomach tightened up because the building didn't look good. ... Then this other officer I'm standing next to said, that building doesn't look straight. So I'm standing there. I'm looking at the building. It didn't look right, but, well, we'll go in, we'll see. So we gathered up rollups and most of us had masks at that time. We headed toward 7. And just around we were about a hundred yards away and Butch Brandies [sic: this should probably be "Brandeis"] came running up. He said forget it, nobody's going into 7, there's creaking, there are noises coming out of there, so we just stopped. (Fire Captain Chris Boyle [14])
- Now we're still worried about 7. We have guys trying to make their way up into the pile, and they're telling us that 7 is going to fall down. (Battalion Chief John Norman [15])
- And 7 World Trade was burning up at the time. We could see it. There was concern. I had gone up to take a look at it, because I knew that the telephone company building, which is 140 West Street, was next to 7 World Trade Center, and there was a concern that if 7 World Trade Center came down, what would happen to this building? ... I went back and I reminded whoever the chief was, I don’t know if it was Chief McKavanagh or Chief Blaich, that with 7 World Trade Center in danger of collapsing, you had to be careful." (Firefighter Eugene Kelty[16])
- The major concern at that time at that particular location was number Seven, building number seven, which had taken a big hit from the north tower. When it fell, it ripped steel out from between the third and sixth floors across the façade on Vesey Street. We were concerned that the fires on several floors and the missing steel would result in the building collapsing. (Fire Chief Frank Fellini[17])
- We were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse. You actually could see there was a visible bulge, it ran up about three floors. It came down about 5 o'clock in the afternoon, but by about 2 o'clock in the afternoon we realized this thing was going to collapse. (Deputy Chief Peter Hayden [18])
- At this point Seven World Trade was going heavy, and they weren't letting anybody get too close. Everybody was expecting that to come down. (Firefighter Vincent Massa[19])
- I couldn't get rid of that feeling like everything is going to collapse. 7 World Trade Center - I couldn't even watch that. I said that's enough. I refused to watch that. (Battalion Chief Tom Vallebuona [20])
- Just when you thought it was over, you’re walking by this building and you’re hearing this building creak and fully involved in flames. It’s like, is it coming down next? Sure enough, about half an hour later it came down. (Lieutenant James McGlynn [21])
[edit] The collapse
WTC7 finally collapsed at 5:20 p.m. A video of the collapse can be seen below.
Based on footage from CNN, the National Institute of Standards and Technology produced this timeline of the events leading to global collapse.[22]
| Interval | Total time | Event |
| 0.0 | 0.0 | Movement of east penthouse roofline. |
| 0.9 | 0.9 | East penthouse kinks between columns 44 and 45. 2 windows at floor 40 fail between columns 44 - 45. |
| 0.3 | 1.2 | 4 windows fail at floor 40. East penthouse submerged from view (now inside building). |
| 0.4 | 1.7 | 3 windows break at floors 41 to 44. |
| 0.5 | 2.2 | East penthouse completely submerged. |
| 1.8 | 4.0 | Windows break along column 46 at floors 37 and 40. |
| 3.0 | 7.0 | North side of west penthouse moves. Movement of entire north face of WTC7 (visible above floor 21). |
| 0.2 | 7.2 | West end of roof starts to move. |
| 0.5 | 7.7 | East end of roof starts to move. Façade kink formed along column 46-47. |
| 0.1 | 7.9 | West penthouse submerged. |
| 0.3 | 8.2 | Global collapse occurs as windows fail between floors 33-39 around column 55 |
The sound of the collapse is described by eyewitnesses (perhaps we should say "earwitnesses") as a "rumbling" sound[23], as the video above confirms. Seismic data[24] show that the duration of the seismic events associated with the fall of WTC7 lasted for about eighteen seconds[25].
[edit] Misconception 1: Controlled demolition
The Truth Movement, for reasons to be discussed below have decided almost unanimously that the collapse of WTC7 was the result of a controlled demolition. In this section we shall review some of the arguments for and against this hypothesis.
[edit] "In its own footprint"
One persistent Truther claim concerning WTC7 and the other building that collapsed on 9/11 is that they "imploded symmetrically into their own footprint", or similar phrases. We should explain that the "footprint" of a building is simply the area that it stands on, and that, when a building to be imploded stands among other buildings, it is the job of a demolition engineer to make sure that a building falls into its own footprint. Hence, the Truth Movement claim, the fact that WTC7 fell into its own footprint is evidence of a controlled demolition.
The problem with this line of reasoning is that WTC7 did not fall into its own footprint. As we have seen above, the radius of the debris field averaged 70 feet[28], and the collapse did severe and sometimes irreparable damage to the surrounding buildings, which is just what every demolition engineer tries to avoid.
Now, clearly this does not rule out the use of explosives placed so as to bring down the tower in a messy and haphazard fashion; but it does mean that the neatness of the collapse cannot be offered as evidence for the use of explosives, since WTC7 did not, in fact, collapse neatly.
[edit] Real controlled demolitions
Controlled demolitions are carried out with explosives. These make a noise.
No skyscraper the size of WTC7 has ever been imploded. The nearest we can get are the implosions of the Hudson's Department Store (the tallest building ever imploded, at 33 stories and 134 meters at its highest point) and the Landmark Tower, Fort Worth (the second tallest building ever imploded, at 30 stories and 116 meters).
Videos of the two implosions are given below.
Video footage of other implosions, of structures less comparable to WTC7, may be found here.
Now, eyewitnesses and video footage both clearly attest to the rumbling noise WTC7 made as it fell; and anyone who could hear that could also a fortiori hear the explosions involved in controlled demolition. Yet there are no reports of this, and no video footage.
This has led some members of the Truth Movement to suggest alternative schemes for demolition involving, not explosives, but incendiaries such as thermite or thermate. We have as yet seen no technical description as to how this feat might be achieved; nor a reason why, if it is possible, demolition companies never employ it.
[edit] Redundancy of the hypothesis
As we have seen above, firefighters expected the collapse of the building, on account of the structural damage[29], the extent of the fire[30], the sagging and bulging of the building[31], and the creaking noises it was making[32][33]. Moreover, as we have seen above, the building started to collapse eight seconds before the initiation of global collapse. There is, then, no mystery to be explained as to why WTC7 came down: it fell down because it was falling down for the reasons that it was expected to fall down.
[edit] Misconception 2: "Pull it"
The interest of conspiracy theorists in WTC7 and controlled demolition was sparked by Larry Silverstein's seemingly innocent use of the word "pull", which they take to mean "blow up" and the word "it", which they take to mean "WTC7".
[edit] What Silverstein said
The infamous "pull" quote, in full, reads:
- I remember getting a call from the uh Fire Department Commander telling me that they were not sure they were gonna be able to contain the fire. And I said y'know we've had such terrible loss of life, maybe the smartest thing to do is, is pull it. Ah, and they made that decision to pull, and then we watched the building collapse. (Larry Sliverstein, appearing on PBS, America Rebuilds: A Year at Ground Zero. Premiered September 10, 2002[34])
It is often subtly or unsubtly misquoted. Video of Silverstein's remarks is given below.
[edit] History
The history of the "pull" quotation and the Truth Movement bears a little examination. As noted, it premiered on PBS on September 10, 2002[35]. However, Silverstein's alleged confession was noted, at the time, by nobody at all.
The discovery of the deep Truthy significance of the words "pull it" were apparently made by one Jeremy Baker, a Truther[36], after seeing a repeat of the program in March 2003. The first time it was aired, neither the journalist interviewing Silverstein, nor, apparently, anyone in the program's audience (including any members of the Truth Movement who were watching) noticed that Silverstein confessed to complicity in the crime of the century.
The obvious reason for this is that his words do not in fact support that interpretation.
[edit] Pulling building 6
The Truther interpretation of "pull" as meaning "blow up" apparently stems from a sequence in the same documentary, in which a demolition worker talks about "pulling" the remains of WTC6 in a context where it is plain that he is talking about demolishing it. An audio clip of this is available in mp3 format here; a video clip is given below:
The only problem with the Truther interpretation of these remarks is that WTC6 was not blown up, it was pulled down, hence "pull building 6". As explained by the folks at implosionworld.com to the Truther Joël v.d. Reijden
- Conventionally, "pull a building" can mean to pre-burn holes in steel beams near the top floor and affix long cables to heavy machinery, which then backs up and causes the structure to lean off its center of gravity and eventually collapse. But this is only possible with buildings about 6-7 stories or smaller. This activity was performed to bring down WTC 6 (Customs) after 9/11 because of the danger in demolishing conventionally.[37]
Hence this sequence of the video does not show that "pull" can mean "cause to implode", as hypothesized by Truthers.
As we have seen from the previous quotation, "pull", as applied to a building, conventionally means "pull down". Experts in demolition testify that it has no other meaning, certainly not "explosively demolish".
- We have never once heard the term 'pull it' being used to refer to the explosive demolition of a building, and neither has any blast team we've spoken with. (Blanchard et al, A Critical Analysis of the Collapse of WTC Towers 1, 2 & 7 from an Explosives and Conventional Demolition Industry Viewpoint [38])
One amusing consequence of all this is that Truthers have started using the word "pull" to mean "blow up" as though they could retrospectively change the meaning of the word and so alter the meaning of Silversten's statement.
[edit] What did Silverstein mean?
Silverstein's account of what Silverstein meant was given in a statement made by Dara McQuillan for Silverstein Properties on September 9 2005:
- In the afternoon of September 11, Mr. Silverstein spoke to the Fire Department Commander on site at Seven World Trade Center. The Commander told Mr. Silverstein that there were several firefighters in the building working to contain the fires. Mr. Silverstein expressed his view that the most important thing was to protect the safety of those firefighters, including, if necessary, to have them withdraw from the building. Later in the day, the Fire Commander ordered his firefighters out of the building and at 5:20 p.m. the building collapsed. [39]
According to his account, then, he meant "pull" in the sense of "abort the operation", "pull out", rather than in the non-existent sense of "blow up". It is not difficult to find other people using phrases such as "pull the mission" or "pull the operation" in just such a way[40][41][42][43][44]. On the other hand, as noted, it is impossible to find anyone but a Truther who uses the word "pull" in the sense of "blow up".
The context also bears examination. In the PBS quote, Silverstein says:
- And I said y'know we've had such terrible loss of life, maybe the smartest thing to do is, is pull it.
Concerns over loss of life are an excellent reason to pull back firefighters from an attempt to save mere property; but it would not be a good reason to blow up a building; under that interpretation of "pull", it comes as a complete non sequitur.
We should note that Silverstein's account fits the facts as we know them: we know that the FDNY did, in fact, abandon attempts to save WTC7; we have no indications of any firefighters trying to blow it up.
Finally, we should note the extreme psychological implausibility of the Truther hypothesis, under which Larry Silverstein wanders into a television studio and absent-mindedly confesses to the world his complicity in the crime of the century. In our experience people don't do that sort of thing.
[edit] Pull: Summary
We have, therefore, two competing hypotheses as to the meaning of Silverstein's remarks.
- For no apparent reason, under no pressure or coercion, Larry Silverstein told a TV camera that he and the FDNY were complicit in 9/11 by conspiring to blow up WTC7, something they managed to do without producing any noise; he chose to make this confession using a phrase which does not mean "blow up", and which is so far from this meaning that when he first made this confession, no-one noticed.
- Larry Silverstein, speaking English rather than some language invented by Truthers, said that he and the FDNY were concerned about the safety of firefighters in the vicinity of WTC7, a concern which we know was justified, and that the firefighters were pulled back from the building, an event that we know took place.
For the various reasons given above, we find the second interpretation more plausible, and will therefore not be joining the little gaggles of Truthers who occasionally congregate around Silverstein's offices shouting "Murderer! Murderer!" and "Pull! Pull!".
![[24]](http://www.ldeo.columbia.edu/LCSN/Eq/20010911_WTC/Bldg7.jpg){kind=link}