|The Tacoma Narrows Bridge is a pair of mile-long suspension bridges in the U.S. state of Washington, which carry State Route 16 across the Tacoma Narrows between Tacoma and the Kitsap Peninsula. They replaced a bridge that was opened to traffic on July 1, 1940 and which became famous four months later for a dramatic wind-induced structural collapse that was caught on motion picture film. The original span's motion earned it the nickname Galloping Gertie.
Due to materials shortages as a result of World War II, it took 10 years to build a replacement bridge, which opened October 14, 1950. The 1950 replacement bridge was sometimes referred to as Sturdy Gertie and, like its predecessor, was the third longest suspension span in the world at the time of its construction. Population growth on the Kitsap peninsula caused traffic to exceed the bridge's vehicle capacity, and a parallel bridge was constructed to carry eastbound traffic, while the 1950 bridge was reconfigured to carry westbound traffic. The new bridge opened July 15, 2007.Contents [hide]
The desire for the construction of this bridge dates back to 1889 with a Northern Pacific Railway proposal for a trestle, but concerted efforts began in the mid-1920s. In 1937, the Washington State legislature created the Washington State Toll Bridge Authority and appropriated $5,000 to study the request by Tacoma and Pierce County for a bridge over the Narrows. The bridge was designed by Leon Moisseiff.
The first Tacoma Narrows Bridge opened to traffic on July 1, 1940. It collapsed four months later on November 7, 1940, at 11:00 AM (Pacific time) due to a physical phenomenon known as aeroelastic flutter caused by a 67 kilometres per hour (42 mph) wind. The bridge collapse had lasting effects on science and engineering. In many undergraduate physics texts the event is presented as an example of elementary forced resonance with the wind providing an external periodic frequency that matched the natural structural frequency (even though the real cause of the bridge's failure was aeroelastic flutter). Its failure also boosted research in the field of bridge aerodynamics/aeroelastics which have themselves influenced the designs of all the world's great long-span bridges built since 1940.
No human life was lost in the collapse of the bridge. However, a small dog who was too scared to leave an abandoned car perished. The collapse of the bridge was recorded on 16mm film by Barney Elliott, owner of a local camera shop, and shows Leonard Coatsworth leaving the bridge after exiting his car. In 1998, The Tacoma Narrows Bridge Collapse was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant." This footage is still shown to engineering, architecture, and physics students as a cautionary tale.
After the collapse, two bridges were constructed in the same general location. The first one, now called the Tacoma Westbound bridge, is 5,979 feet (1822 m) long — 40 feet (12 m) longer than Galloping Gertie. The second one, the Tacoma Eastbound Bridge, opened in 2007.