The Checklist Manifesto_ How to Get Things Right - Atul Gawande [28]
So what did they do? They did not scrap the building or shrink it to a less ambitious size. Instead, McNamara proposed a novel solution called a “tuned mass damper.” They could, he suggested, suspend an immense four-hundred-ton concrete block from huge springs in the building’s crown on the fifty-ninth floor, so that when wind pitched the building one way, the block would swing the other way and steady it.
The solution was brilliant and elegant. The engineers did some wind-tunnel testing with a small model of the design, and the results were highly reassuring. Nonetheless, some chance of error and unpredictability always remains in projects of this complexity. So the builders reduced their margin of error the best way they knew how—by taking a final moment to make sure that everyone talked it through as a group. The building owner met with the architect, someone from the city buildings department, the structural engineers, and others. They reviewed the idea and all the calculations behind it. They confirmed that every concern they could think of had been addressed. Then they signed off on the plan, and the skyscraper was built.
It is unnerving to think that we allow buildings this difficult to design and construct to go up in the midst of our major cities, with thousands of people inside and tens of thousands more living and working nearby. Doing so seems risky and unwise. But we allow it based on trust in the ability of the experts to manage the complexities. They in turn know better than to rely on their individual abilities to get everything right. They trust instead in one set of checklists to make sure that simple steps are not missed or skipped and in another set to make sure that everyone talks through and resolves all the hard and unexpected problems.
“The biggest cause of serious error in this business is a failure of communication,” O’Sullivan told me.
In the Citicorp building, for example, the calculations behind the designs for stabilizing the building assumed the joints in those giant braces at the base of the building would be welded. Joint welding, however, is labor intensive and therefore expensive. Bethlehem Steel, which took the contract to erect the tower, proposed switching to bolted joints, which are not as strong. They calculated that the bolts would do the job. But, as a New Yorker story later uncovered, their calculations were somehow not reviewed with LeMessurier. That checkpoint was bypassed.
It is not certain that a review would have led him to recognize a problem at the time. But in 1978, a year after the building opened, LeMessurier, prompted by a question from a Princeton engineering student, discovered the change. And he found it had produced a fatal flaw: the building would not be able to withstand seventy-mile-an-hour winds—which, according to weather tables, would occur at least once every fifty-five years in New York City. In that circumstance, the joints would fail and the building would collapse, starting on the thirtieth floor. By now, the tower was fully occupied. LeMessurier broke the news to the owners and to city officials. And that summer, as Hurricane Ella made its way toward the city, an emergency crew worked at night under veil of secrecy to weld two-inch-thick steel plates around the two hundred critical bolts, and the building was secured. The Citicorp tower has stood solidly ever since.
The construction industry’s checklist process has clearly not been foolproof at catching problems. Nonetheless, its record of success has been astonishing. In the United States, we have nearly five million commercial buildings, almost one hundred million low-rise homes, and eight million or so high-rise residences. We add somewhere around seventy thousand new commercial buildings and one million new homes each year. But “building failure”—defined as a partial or full collapse of a functioning structure—is exceedingly rare, especially for skyscrapers. According to a 2003 Ohio State University study, the United States experiences an average of just twenty serious “building failures” per