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The Tacoma Narrows Bridge consists of two suspension bridges across the narrowest point of Puget Sound in the US state of Washington, between the city of Tacoma and the Kitsap Peninsula. The first Tacoma Narrows Bridge, and the bridge most often referred to in popular culture, opened in the summer of 1940 and collapsed four months later. A newer, much safer bridge was constructed in 1950, and a twin to this bridge was added in 2007.
Seeing a need for a bridge connecting the Kitsap Peninsula and the city of Tacoma, cutting many hours of travel time between the two areas, the Washington state legislature authorized a bridge. When the Tacoma Narrows Bridge opened, in July of 1940, it was the third longest suspension bridge in the world, spanning more than 1 mile (1.6 km). On November 11, 1940 the bridge suffered catastrophic failure and collapsed after a strong wind induced a harmonic oscillation, causing the bridge to literally shake itself to pieces and earning it the nickname of Galloping Gertie. This failure is still used as an example and cautionary model for engineering and architecture students. The wreckage of the original bridge has become an unintentional man-made reef and is protected by United States federal law.
After World War II, a new bridge was built, using the lessons learned from the failure of the first bridge. The new bridge, which is also known as the Tacoma Narrows Bridge, was completed in 1950 and is still in use today, having proven to be much more soundly designed than the earlier, failed bridge. This second bridge, when constructed, was still the third longest suspension bridge in the world.
As the entire region developed, and traffic flow increased yearly, it became apparent, at the end of the 1990s, that the single bridge was becoming insufficient for the number of vehicles it handled daily. A new bridge, designed as a twin to the 1950 bridge, was approved by Washington state voters in 1998. The second span, located alongside the existing bridge, was completed in 2007, and traffic flow was configured in such a way that all westbound traffic would use the 1950 bridge, and all eastbound traffic would use the new bridge. Today, this pair of bridges are known collectively as the Tacoma Narrows Bridge.