Ramblings & ephemera

Failure every 30 years produces better design

From The New York Times‘ “Form Follows Function. Now Go Out and Cut the Grass.“:

Failure, [Henry] Petroski shows, works. Or rather, engineers only learn from things that fail: bridges that collapse, software that crashes, spacecraft that explode. Everything that is designed fails, and everything that fails leads to better design. Next time at least that mistake won’t be made: Aleve won’t be packed in child-proof bottles so difficult to open that they stymie the arthritic patients seeking the pills inside; narrow suspension bridges won’t be built without “stay cables” like the ill-fated Tacoma Narrows Bridge, which was twisted to its destruction by strong winds in 1940.

Successes have fewer lessons to teach. This is one reason, Mr. Petroski points out, that there has been a major bridge disaster every 30 years. Gradually the techniques and knowledge of one generation become taken for granted; premises are no longer scrutinized. So they are re-applied in ambitious projects by creators who no longer recognize these hidden flaws and assumptions.

Mr. Petroski suggests that 30 years – an implicit marker of generational time – is the period between disasters in many specialized human enterprises, the period between, say, the beginning of manned space travel and the Challenger disaster, or the beginnings of nuclear energy and the 1979 accident at Three Mile Island. …

Mr. Petroski cites an epigram of Epictetus: “Everything has two handles – by one of which it ought to be carried and by the other not.”

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