How to Build a Better Bridge
This article is from the archive of The New York Sun before the launch of its new website in 2022. The Sun has neither altered nor updated such articles but will seek to correct any errors, mis-categorizations or other problems introduced during transfer.
In 1989, in the midst of a windstorm, Leslie Pluhar was driving across the Mackinac Bridge, which joins the Upper and Lower Peninsulas of the state of Michigan. Apparently concerned by the weather, she stopped her tiny Yugo on the bridge – a fatal mistake, for the car was caught by the gale and thrown 150 feet into the strait below.
Henry Petroski does not discuss Pluhar’s tragic death in his new book, “Pushing the Limits” (Alfred A. Knopf, 304 pages, $25), but he does help to explain it. The Mackinac was built with a rather unique feature. The designers feared that strong wind might set the bridge in motion, and so its span consists in large part of open steel grating that allows the air to pass harmlessly through. Unfortunately, this also creates an upward force on each car, which must be counteracted by a downward force – in other words, keep driving.
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