The Tacoma Narrows Bridge twisted apart in the wind
On this day · 7 November 1940
Four months after opening, a 42-mph breeze set 'Galloping Gertie' twisting until the suspension span tore itself to pieces.
On the morning of 7 November 1940, the Tacoma Narrows Bridge in Washington State collapsed in a wind of only about 42 miles per hour—just four months after it opened. Workers had nicknamed it “Galloping Gertie” for the way its deck rippled and bounced in even gentle breezes.
That morning the motion changed from a vertical roll into a violent torsional twist, the two halves of the 2,800-foot main span corkscrewing in opposite directions. As the structure absorbed more and more wind energy, the oscillations grew until suspender cables snapped and the deck plunged into Puget Sound.
No one died, though a stranded cocker spaniel named Tubby went down with the bridge.
The failure became engineering’s most-watched cautionary tale. It overturned the prevailing “deflection theory” and made aerodynamic stability a permanent concern in suspension-bridge design.
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