Even from the distance of 23 years, the memory of the fellow-feeling that emerged from 9/11 still surges in the chest, binding at the level of the human heart strangers who would swear they have nothing in common.
But even decades later, the lessons of that day are much less clear. The most obvious takeaways (improve airport security) are also the most conspicuous, while the less visible might be apparent only to experts. Which is where Engineers at Ground Zero comes in.
The documentary—scheduled for release in November, with a short featured here on TIME.com—picks up a few hours after the Towers fell, as the search for survivors was supplanted by the search for answers: Were the surrounding buildings safe? Were some 400 buildings below 14th Street safe? How about the ground beneath our feet? And ultimately: How had this happened?
The people who could find answers gathered among the firefighters and demolition crews. Structural engineers became “second responders,” dressed in civilian clothes and versed in the laws of tension and compression—all the arcana of physical geometry that had determined whether lives would be lost or saved in the 101 minutes that elapsed between the impact of American Airlines Flight 11 into the North Tower and its collapse. The engineers stayed for months, leaving when the site was emptied and the answers were in hand.
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“What did we learn from 9/11?” Vicki Arbitrio, who helped organize fellow engineers in Lower Manhattan, tells TIME. “We learned to make stairwells wider, so that firefighters can go up while others go down. We learned that maybe the walls around the stairs should be more than just gypsum board, and that maybe we should keep the sprinkler mains within those hardened walls. Things that will protect people in the future. Redundancy in the overall structural system to make sure that, you know, a building will still stand up for a little while.”
The film includes a…
