On July 1, 1940, the Tacoma Narrows Bridge, at that time the third longest suspension span in the world, was finally built.
But four months later, the bridge, also known as “Galloping Gertie,” had a brutal ending!
The majestuous bridge across Puget Sound started swaying like a river and collapsed during a windstorm (42 mile-per-hour wind) on November 7, 1940.
This is a sound version of the event:
The most dramatic failure in bridge engineering
The Tacoma Narrows Bridge is probably best known as “the most dramatic failure in bridge engineering history.” To discourage salvagers, Galloping Gertie has been declared a National Historic Landmark. Here a longer and color version video of this incredible phenomenon:
A real American saga
This story is known around the world… A real American saga. No reports of casualties except a dog trapped in a car stranded on the bridge. Although a rescue was attempted the frightened animal would not leave the car. This amazing accident has changed how engineers now design suspension bridges by using the safer and moderner suspension spans of today. The Tacoma Narrows Bridge has been reconstructed in 1950 as a pair of twin suspension bridges.
What did happen?
In many physics textbooks, the event is presented as an example of elementary forced resonance with the wind providing an external periodic frequency that matched the bridge’s natural structural frequency, though the actual cause of failure was aeroelastic flutter.