Truthers, over and out
NIST report credibly explains fall of WTC 7
August 26, 2008
"What about World Trade Center 7?"
That question has always been the trump card for the " 9/11 Truthers" - conspiracy buffs who have peddled the mind-boggling theory that the 2001 attacks on the World Trade Center and the Pentagon were an inside job, plotted and even executed by the federal government as a way to justify the war on terror.
The answer to the Truthers' question - how that 47-story building could collapse into a fiery heap when it wasn't hit by a plane - was provided definitively in a report issued last week by the National Institute of Standards and Technology. The NIST report is so exhaustive that it should put to rest wild notions, including one suggesting that bombs were planted in the structure and detonated to erase key evidence about the plot.
That said, we're not about to believe for a New York minute that the loopier 9/11 Truthers will accept those findings.
The more level-headed among us have little trouble accepting the uncomplicated (and hence credible) explanation that the 9/11 attacks were devised by Osama bin Laden and fellow jihadists to demonstrate the vulnerability of the "decadent" West to terror attacks.
Not so fast, the Truthers have insisted. What about WTC 7? Why would that structure collapse seven hours after the Twin Towers fell unless it was brought down by a controlled detonation?
The explanation, quite simply: uncontrolled fires, which burned to an intensity hot enough and long enough to compromise the steel girders holding up the structure.
The 66-page report, available at wtc.nist.gov, resulting from a three-year technical investigation, including simulations of the event, noted that the debris from World Trade Center Building 1 ignited fires on at least 10 lower floors of WTC 7. Fires on floors 7 through 9 and 11 through 13 burned for at least seven hours.
They raged unabated because the building's primary and secondary water source for sprinklers on the bottom 20 floors originated from city water mains - and those water lines were damaged by the impact of the Twin Towers collapse.
Without any way to feed water to sprinklers, fires from office furniture and paper rose to temperatures that caused the steel girders to expand. Temperatures weren't hot enough to melt the girders, but without any relief, over time the expansion compromised their integrity. A girder on the 13th floor lost contact with one of the 81 columns supporting the building. That floor collapsed, taking the eight floors below it.
Then one interior column buckled. When it failed, the 23 other central columns supporting the building soon followed, and the structure could no longer support itself.
"This is the first time that we are aware of that a building taller than about 15 stories has collapsed primarily due to fires," said NIST lead investigator Shyam Sunder at a Thursday press conference.
This unprecedented event has highlighted structural vulnerabilities in other skyscrapers. And the report offered 13 recommendations for ways to make those buildings safer - some as minor as redesigning work spaces to prevent fires from spreading from one cubicle to another.
The NIST report might not placate the more unhinged Truthers. But it should prod building owners to take small steps that prevent future tragedies.