How the Pentagon's design enabled hundreds to evacuate to safety on 9/11 | 60 Minutes Archive
In a Nutshell
The Pentagon survived a direct 757 impact on 9/11 because its renovated section—completed just five days prior—incorporated blast-resistant steel framing, ballistic fabric to contain debris, and specially designed windows that prevented immediate structural collapse, allowing hundreds to evacuate safely before the floors fell after 35 minutes. This design was based on classified research analyzing prior terrorist attacks like Oklahoma City and Khobar Towers, which informed redundant structural supports and materials to minimize flying debris and progressive collapse. The survival of 125 victims (instead of potentially thousands) validated the effectiveness of these retrofits, now being used to improve future building protections.
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Even though 125 people were killed in the Pentagon on September 11th, there was something miraculous about that day. The 757 obliterated the first and part of the second floor, but the third, fourth, and fifth floors remained suspended in midair for 35 minutes. Hundreds of people escaped. The answer lies in a partially classified government study of terrorist bombings that had come before, including Oklahoma City and Khobar Towers. Everything learned in that project was hidden inside the walls of the Pentagon itself in anticipation that one day the building would be bombed.
John Yates, a civilian security manager in the Pentagon, was in his office watching the World Trade Center on TV. Five minutes before the plane hit, someone said, "Come over. You got to see what's going on." He walked over to watch television and called his wife. She asked him jokingly to do the rest of his work for the remainder of the day from underneath his desk. He joked back, "Yeah, okay, honey, I will." He walked back to watch more of what was happening in New York and had been standing there for just a couple of minutes when the plane hit the building.
Yates described the sound as "deafening. Absolutely deafening." He remembered "this bright ball of fire that just went right over my head." The fire burned 35% of his body. The plane hit directly below his office, but the floor held, giving some, but not all, a chance to live. There were people standing next to him in the room watching television. The lady standing to his left didn't make it. They were standing "within an arm's length" of him.
Yates survived in part because his floor was reinforced and held up for half an hour. In an astonishing stroke of luck, the terrorists had hit the only section of the Pentagon designed to resist a terrorist attack. Lee Evey runs a billion-dollar project to renovate the Pentagon that had been working on it since 1993. The first section was five days away from being finished when the terrorists hit it with the 757.
Several modifications were made to the building as part of the renovation that helped save people's lives. To see how so many escaped, you have to look inside the walls. The renovation project built strength into the 60-year-old limestone exterior with a web of steel beams and columns. Steel tubes start on the first floor and go all the way up to the fifth floor. All the way through from floor to floor, everything is bolted together with horizontal steel as well as the vertical steel, creating one strong matrix of steel supports that cases the windows and provides tremendous additional strength to the wall.
When the plane hit at 350 mph, the limestone outside shattered. But inside, those shards of stone were caught by a shield of cloth that lines the entire section of the building. This is a ballistic type cloth that helps prevent masonry from fragmenting and blowing through an area where there are people. It's essentially a bullet-resistant vest for the building, made from the same type of material used in bullet-resistant vests. All of this, especially the steel, held up the third, fourth, and fifth floors. They stayed suspended for 35 minutes. Only after the evacuation did the heat melt the new steel away.
If that area had not been renovated, the wall might have collapsed immediately, looking at the number of columns and support structures that were otherwise completely destroyed. Lieutenant General Bob Flowers commands the Army Corps of Engineers. The Corps helped design the Pentagon's new protection. The engineers studied past attacks, including the 1983 Marine barracks bombing in Lebanon, Oklahoma City in 1995, the US embassies in East Africa, and the Khobar Towers barracks in Saudi Arabia.
At Khobar Towers, most of the damage and casualties were caused by flying debris from the structure and from the glass. Based on that, engineers worked to design things to prevent flying debris and flying glass. At Oklahoma City, the bulk of the casualties were caused by the collapsing structure. One of the things studied was how to put redundant capability in a structure to prevent it from collapsing if it was attacked. By applying lessons learned from doing those studies, structures can be better protected in the future.
The Corps of Engineers is making a science of terror, setting off its own bombs. This is the first time the public has been allowed to see the Corps's counterterrorism work at its research center in Mississippi. Reed Mosher is the technical director for survivability. The team develops specialists that go to terrorist strikes as soon as they happen to get the most information of what occurred before things are moved, repair work starts, or removal for search begins.
The goal is to find out what performed well, what didn't perform well, and try to characterize the size of the bomb and the blast. Mosher designs his own terrorist bombings in miniature with exacting scale models of reinforced concrete buildings. One model was scaled down to a quarter scale, using concrete masonry units scaled down to build the walls inside of it.
On one day, Mosher's team was testing a common interior wall: particle board, steel wall studs, and sheetrock. It was set in a steel frame with instruments inside. Once the area was all clear, they set off a bomb. Inside, the destruction was captured in slow motion. Hundreds of these tests have been done to create new kinds of building materials.
A concrete wall was tested, and then the same kind of wall was tested after being sprayed with a new plastic coating. The Corps of Engineers runs these experiments through its supercomputer center, one of the most powerful in the nation. The computer can test various kinds of bombs against different buildings without breaking any glass. In a special 3D imaging room, Mosher showed how the supercomputer recreates the blast wave at Khobar Towers and predicts the path of every shard of glass from a single breaking window.
These studies have helped create a new generation of windows that can stand up to tremendous force. New windows can be fitted into an old building. The window is strapped in like a seatbelt. It pops a couple of feet and stops. The Corps has tested more than 100 window designs the hard way. The new windows have glass on the outside, glass on the inside with a plastic sheet in the middle. This retains all the glass particles when hit, and they all crack but are actually connected into the frame so that it gives strength to keep it from blowing in.
The renovated section of the Pentagon had just been fitted with blast-resistant windows. US Army Lieutenant Colonel Vince Cam was sitting next to one of those windows. He was sitting basically about 3 feet away from the window. With the loud bang, he could see a fireball that came up towards the window. The fireball was much brighter than the sun, like a stove - bright reddish orange. But neither the heat nor the force broke through the windows that were right next to the impact site. The Pentagon's new windows cost $10,000 apiece. No one has counted how many lives they saved. If Cam had been sitting in the same window on the unrenovated part of the Pentagon, he probably wouldn't have survived.
Lee Evey's team has finished tearing down the section that they had just put up - 400,000 square feet. About 10% of the Pentagon is gone. Already the new Pentagon is rising. Steel rods that will support the new columns are being sunk into the same old pilings. September 11th will always be an essential date for the Pentagon. It was September 11th, 1941, that ground was broken for the building. On September 11th, 2002, they intend to open the new section. It will look exactly like it looked before. Limestone is already being pulled from the same Indiana quarry of 60 years ago.
In Mississippi, the supercomputers are analyzing the September 11th attack to improve the defenses even more. John Yates has already been told that he will be moving back into the very same office. It's a testament to the work that the people in the renovation did and the engineers. If it hadn't been done, if there'd been no structural hardening, the death and destruction would have been more catastrophic than what it is - 10 times, 100 times worse. Yates doesn't ask why anymore. He just says thank you.
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