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Tacoma Narrows Bridge

Posted Tuesday, March 27, 2012 at 4:05 AM

"Engineers learned a great deal when wind collapsed the Tacoma Narrows Bridge."

Tacoma Narrows Bridge

PostedTuesday, March 27, 2012 at 4:05 AM

Tacoma Narrows Bridge

Engineers learned a great deal when wind collapsed the Tacoma Narrows Bridge.

After the Federal Government refused to pay $11 million to build a bridge that crossed the Tacoma Narrows (cutting at least 40 miles off the trip between Tacoma and Bremerton, WA), the state turned to engineer Leon Moisseiff. Moisseiff calculated that he could design a thin-plate girder-type bridge for only $6.4 million. On July 1, 1940, after two years of construction, the first Tacoma Narrows Bridge was opened to the public. As soon as the bridge opened, it was noticed that it would twist and turn in even the smallest wind. People gave it the nickname, "Galloping Girtie." Just four months and one week after opening, on November 7, 1940, the bridge collapsed during a 42-mph windstorm. A second bridge was built and opened to the public in 1950. This time, before building the bridge, engineers built a model of the new bridge and tested it in a wind tunnel. They learned that wind would have to pass through or over the bridge instead of the bridge "capturing" the wind, which would make it oscillate and collapse like the first one.

More on the Tacoma Narrows Bridge.