Who Got Out and Why

I spent today reading the lengthy report by the National Institute for Standards and Technology about who escaped from the 9.11 World Trade Center attacks, and why. If you have a taste for this sort of thing, the report will inspire you with both pride and fear. Pride for two reasons:

First, the report is a real show of technical intelligence, dispassion, and rigor. The research design is a thing of beauty. The questions are well defined and clearly stated. The lessons are important, touching on everything from the design of elevator doors to policies for evacuations.

Another source of pride is the behavior of the occupants of both buildings in the time between the impact of the planes and the collapse of the structures. This includes, of course, the “acts of everyday heroism” that are credited by the report’s authors with saving many lives. But it also includes the general rationality and common sense displayed by the many evacuees who used their own sources of information to reach independent decisions about how to escape, often in the face of misleading or contradictory advice. In the floors below the impact zone, a vast majority survived, despite the tremendous distances they had to descend. One interest fact: there was no significant variation between survival rates for disabled and non-disabled evacuees. Those who could not make it down on the their own were helped.

But the report was also frightening, because the relatively successful evacuation of occupants who were below the impact zone when the planes hit was clearly due, in part, to luck. The buildings were far below full capacity at that early hour. Using a careful analysis of evacuation conditions in both buidlings, the report estimates that, had the planes hit when they were full, over 14,000 people may have died.

The draft report, which is open for public comment, is available at:

Scroll down the page and look for:
Draft report on Project 7: Occupant Behavior, Egress, and Emergency Communications (Draft)

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