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While most of us watched the twin towers blazing on TV screens, the people inside were unwitting participants in a huge experiment. It tested whether an aging and increasingly obese workforce was slowing the escape, whether people on the stairs were pausing to let folks enter from lower floors, if anyone took charge, if anyone ditched their bosses, and when and why people first thought they might die.
September 11 was certainly unique, but what went on in the stairwells that day challenged assumptions that go into designing high-rise buildings everywhere. World Trade Center survivors hold a wealth of information that could translate into new ways of building structures to protect people. That's why Edwin Galea, a fire safety expert from the University of Greenwich, outside London, and six behavioral psychologists have come to New York to collect the stories of the people who made it out.
Several studies have already probed various aspects of 9-11; the National Institute of Standards and Technology devoted a whole report to how people escaped. But the NIST conducted few in-person interviews, ran a telephone survey that locked respondents into rigid answers, and focused mainly on what people did before they evacuated.
The researchers in Galea's study will do it differently. In possibly the largest study of its kind ever undertaken, they aim to interview 2,000 survivors. They'll be asked to remember how their day started, where they ate breakfast, how they traveled to work, and how the disaster unfolded. They'll tell the story in free-flow fashion.
For some, the process could be painful. Participants will be told they can stop the interview at any time. But in a pilot study Galea ran with about 50 survivors, that never happened. "They almost view it as therapeutic," Galea says. "It's the feeling that it might be doing something constructive."
What's already known about 9-11 could reshape emergency preparations. It seems that when fleeing for their lives, people in the towers listened to the same line managers who directed their everyday work. So perhaps managers ought to be trained as fire wardens. Witness reports of staircases littered with high heels suggest that women should bring "sensible shoes" to work in case they need to get out fast.
Other observations only raise more questions. High-rise designs assume that people react to an emergency fairly quickly, Galea says, but in the twin towers some apparently waited for 10 minutes, 20 minutes, even an hour before leaving. Why? Regulations also assume that people evacuate as individuals, but in the WTC many descended in groups. The problem is that groups move only as fast as their slowest member. Researchers also wonder if employees at strictly hierarchical firms waited for orders instead of just heading for the exits, and when and why people perceived risk. "If we know that, then we can perhaps provide better targeted information so people can make better decisions for themselves," Galea says. (To sign up for the study, go to wtc-evacuation.com.)
The most crucial questions relate to what happened on the stairs. Survivors can tell researchers how dense the crowds were and describe how the flows of people from the floors merged into the columns heading down. That evidence might help solve the biggest riddle from the stairwells: why the evacuation was so slow.
Engineers expect people in a high-rise emergency to descend three to four stories a minute, but on 9-11 they managed only half that speed. This could be because of the density of the crowds (although the towers were only about half full) or the counterflow of rescuers coming up the same stairwells. The width of the stairs may also have played a role. And then there were the evacuees themselves. Studies to date have shown a surprisingly high proportion were slowed by a disability, bad heart, asthma, bad knees, or just being too fat.
In an emergency, a host of problems come with slow walkers, especially if they are large. They might slow down others, be too wide to pass, and exhibit what experts call "exaggerated body sway." If a large person gets injured in an evacuation, the problems are compounded. The bigger they are, the more likely they will block the stairs and the harder it will be for rescuers to lift them out.
If people are moving more slowly these days, it means either that buildings have to last longer in a fire (meaning more costly fireproofing), the stairs have to be wider (meaning less rentable space), or there has to be an alternative for those too slow to walk down. Taking the elevator in a fire has always been a no-no, but for the hefty or disabled it might be the best way to safetyeventually. Jake Pauls, a D.C.-area consultant and expert on emergency evacuations, says that for now, "stairs are the only lifeboats we have in these buildings."
High-rise fires are rare. But fires aren't the only reason for evacuating big buildings. The twin towers were emptied thrice in three decades: on 9-11, after the '93 bombing, and because of a 1977 bomb threat. Nowadays a pile of white powder near the air vents could also send high-rise tenants scrambling.
Buildings might not be ready for that. "The real issue is, no high-rise building anywhere in the world is designed for a full evacuation," says Galea. Instead, engineers expect big buildings to be evacuated in phases. "We cannot continue to build with that assumption," Galea adds. "Can you expect people to evacuate in a phased manner after 9-11?"
Galea's been studying emergencies for 20 years. He helped assemble a database of 2,000 reports from airplane accidents, and his research center's website offers animations of people fleeing hypothetical boat sinkings and real-life stuff like a 1998 disco fire in Sweden. Galea interviewed survivors of a 1999 rail disaster in London and is trying to learn more about the 2003 nightclub fire in Rhode Island. It's made him careful. "In an airplane, I don't want to be more than seven seats away from an exit," he says. "In high-rise buildings, I will always check the evacuation route." He always carries a protective smoke hood and sits facing backward on trains.
But the WTC survivor study isn't motivated by morbid curiosity. "It's not just for science. It's to improve regulations around the world," Galea says. "Building codes for too long have been shaped around what engineers think people do in evacuations and what engineers want people to do."
Few things sound as dreadfully dull as the New York City Building Code, but its minutiae can have life-or-death consequences. The Port Authority is exempt from the code but says the WTC was designed according to the city's guidelines anyway. So changes to the code during the '60s altered the plan for the towers. For example, there were fewer staircases than first planned, narrower doors, no specially constructed fire stairwells, and thinner fireproofing on some walls. The building code also regulates how far apart exits must bewhich can be crucial. The reason some people in the south tower escaped from above the impact zone is that United Flight 175 struck where the staircases were far apart. In the north tower, American Flight 11 hit where the exits were clumped close together, destroying all the passages. The NIST estimates that if the towers had been full at the moment of the 9-11 attacks, 14,000 people would have diedwith 7,700 trapped above the impact zone.
The question is whether Galea's findings, due in late 2007, really will have a chance to influence building design here. New York City is revising its building and fire codes, but that process is nearing an end. The Freedom Tower has already been designed and redesigned. WTC 7 is already signing up tenants.
But it's not as if the threat to high-rises will go away soon. Pauls, the evacuation consultant, began studying building evacuations in Ottawa in the '70s because of a fear of terrorismnamely from the Quebecois separatists. Threats come and go. For most working stiffs, a Chinese proverb that Pauls quotes is instructive: "Of the 39 ways to escape danger, running away is best."