To Forgive Design

Understanding Failure, Henry Petroski, Belknap-Harvard.

“What should surprise us, really, is not that failures occur but that they do not do so more often,” writes longtime failure analyst Henry Petroski in this sequel to “To Engineer is Human: The Role of Failure in Successful Design.” As was the case in his 1985 book, Petroski extensively addresses bridge failures—including the Tacoma Narrows (1940), the Tay Bridge (1879), and London’s Millennium Bridge (2000), to name but a few. What’s new here is that Petroski goes beyond pure engineering to look at design from a broader perspective -- to identify additional causes of failure in made things and systems.

Petroski touches on failures large and small, covering everything from Boston’s Big Dig to Aloha Airlines flight 243 (1988) to Nodar Kumaritashvili’s tragic death on the luge course at Whistler Sliding Centre just prior to the Vancouver Winter Olympics in 2010. Among his points of emphasis: Design does not occur in a technological or political vacuum. (In other words, issues of cost, risk, and economic, social, and political considerations can take precedence over purely technical considerations.) 

He also stresses that simply replicating proven designs may minimize the likelihood of failure, but also inhibits experimentation and innovation. And he notes that there is a striking regularity in terms of occurrence of major disasters (three decades in the case of bridge collapses, for example), which may be attributed to factors like: an irrational sense of overconfidence tied to prolonged success, and the loss of institutional knowledge and memory.

Of course, no amount of study or attention will ever be sufficient to prevent all technological and engineering failures. “The best we might hope for is to maximize our ability to prevent them and thereby minimize their future occurrence,” writes Petroski, who believes that the surest way to avoid pitfalls is to be aware of those that have previously ensnared us. “No matter how devastating a failure,” he says, “its consequences can be even greater if its lessons are not learned and heeded.”