Tacoma Narrows Bridge (1940)


The original Tacoma Narrows Bridge
on its opening day on July 1, 1940

Coordinates: 47°16'N 122°33'W
Other name(s): Galloping Gertie

Characteristics
Design: Suspension
Total length: 5,939 feet (1,810.2 m)
Longest span: 2,800 feet (853.4 m)
Clearance below: 195 feet (59.4 m)

History
Opened: July 1, 1940
Collapsed: November 7, 1940

The 1940 Tacoma Narrows Bridge, the first Tacoma Narrows Bridge, was a suspension bridge in the U.S. state of Washington that spanned the Tacoma Narrows strait of Puget Sound between Tacoma and the Kitsap Peninsula. It opened to traffic on July 1, 1940, and dramatically collapsed into Puget Sound on November 7 the same year. The bridge's collapse has been described as "spectacular" and in subsequent decades "has attracted the attention of engineers, physicis, and mathematicians". Throughout its short existence, it was the world's third-longest suspension bridge by main span, behind the Golden Gate Bridge and the George Washington Bridge.

Construction began in September 1938. From the time the deck was built, it began to move vertically in windy conditions, so construction workers nicknamed the bridge Galloping Gertie. The motion continued after the bridge opened to the public, despite several damping measures. The bridge's main span finally collapsed in 40-mile-per-hour (64 km/h) winds on the morning of November 7, 1940, as the deck oscillated in an alternating twisting motion that gradually increased in amplitude until the deck tore apart.

The portions of the bridge still standing after the collapse, including the towers and cables, were dismantled and sold as scrap metal. Efforts to replace the bridge were delayed by the United States' entry into World War II, but in 1950, a new Tacoma Narrows Bridge opened in the same location, using the original bridge's tower pedestals and cable anchorages. The portion of the bridge that fell into the water now serves as an artificial reef.

The bridge's collapse had a lasting effect on science and engineering. In many physics textbooks, the event is presented as an example of elementary forced resonance, but it was more complicated in reality; the bridge collapsed because moderate winds produced aeroelastic flutter that was self-exciting and unbounded: for any constant sustained wind speed above about 35 mph (56 km/h), the amplitude of the (torsional) flutter oscillation would continuously increase, with a negative damping factor (i.e., a reinforcing effect, opposite to damping). The collapse boosted research into bridge aerodynamics-aeroelastics, which has influenced the designs of all later long-span bridges.

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Design and construction

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Program for the opening
of the Tacoma Narrows
Bridge, June 30, 1940

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Attempt to control structural vibration

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The Washington Toll Bridge Authority hired Professor Frederick Burt Farquharson, an engineering professor at the University of Washington, to make wind-tunnel tests and recommend solutions in order to reduce the oscillations of the bridge. Professor Farquharson and his students built a 1:200-scale model of the bridge and a 1:20-scale model of a section of the deck. The first studies concluded on November 2, 1940—five days before the bridge collapse on November 7. He proposed two solutions:

• To drill holes in the lateral girders and along the deck so that the air flow could circulate through them (in this way reducing lift forces).
• To give a more aerodynamic shape to the transverse section of the deck by adding fairings or deflector vanes along the deck, attached to the girder fascia.

The first option was not favored because of its irreversible nature. The second option was the chosen one, but it was not carried out, because the bridge collapsed five days after the studies were concluded.

Collapse

The wind-induced collapse occurred on November 7, 1940, at 11:00 a.m. (Pacific Time), because of a physical phenomenon known as aeroelastic flutter.

Leonard Coatsworth, an editor at The News Tribune in Tacoma, was the last person to drive on the bridge:

Around me I could hear concrete cracking. I started back to the car to get the dog, but was thrown before I could reach it. The car itself began to slide from side to side on the roadway. I decided the bridge was breaking up and my only hope was to get back to shore."

"On hands and knees most of the time, I crawled 500 yards or more to the towers… My breath was coming in gasps; my knees were raw and bleeding, my hands bruised and swollen from gripping the concrete curb… Toward the last, I risked rising to my feet and running a few yards at a time… Safely back at the toll plaza, I saw the bridge in its final collapse and saw my car plunge into the Narrows.

Tubby, Coatsworth's cocker spaniel, was the only fatality of the Tacoma Narrows Bridge disaster; he was lost along with Coatsworth's car. Professor Farquharson and a news photographer attempted to rescue Tubby during a lull, but the dog was too terrified to leave the car and bit one of the rescuers. Tubby died when the bridge fell, and neither his body nor the car was ever recovered. Coatsworth had been driving Tubby back to his daughter, who owned the dog. Coatsworth received US$450.00 (US$7,700 with inflation) for his car and US$364.40 (US$6,200 with inflation) in reimbursement for the contents of his car, including Tubby.

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Tacoma Narrows Bridge Collapse (1940)
432,079 views • Nov 11, 2012

All Classic Video
46.5K subscribers

Footage of the original Tacoma Narrows bridge wobbling and eventually, collapsing from the Stillman Fires Collection.

The 1940 Tacoma Narrows Bridge was the first incarnation of the Tacoma Narrows Bridge, a suspension bridge in the U.S. state of Washington that spanned the Tacoma Narrows strait of Puget Sound between Tacoma and the Kitsap Peninsula. It opened to traffic on July 1, 1940, and dramatically collapsed into Puget Sound on November 7 of the same year. At the time of its construction (and its destruction), the bridge was the third longest suspension bridge in the world in terms of main span length, behind the Golden Gate Bridge and the George Washington Bridge.

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Tacoma Bridge Collapse: The Wobbliest Bridge in the World? (1940) | British Pathé
1,505,556 views • Jun 18, 2013

British Pathé
1.13M subscribers

Was Tacoma Narrows Bridge the wobbliest bridge in the world? Check out this amazing footage of the collapse of the world's third largest suspension bridge (at the time), Tacoma Narrows Bridge, Washington, in 1940. The only casualty was a dog who had been left in a stalled car by its owner.

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Watch here the clip "Bomber Crashes into Empire State Building" from 1945: https://goo.gl/ABdo5e

Galloping Gertie - The Collapse of the Tacoma Narrows Bridge
79,349 views • Jul 19, 2012

Washington History
103 subscribers

Galloping Gertie -- The Collapse of the Tacoma Narrows Bridge examines the creation and demise of the original Tacoma Narrows Bridge. Produced by Koyo Kim and Raluca Ifrim for National History Day 2007.

From WSHS' collections. Catalog ID: 2011.41.1.2

Find more videos like this in our collections: http://www.washingtonhistory.org/research/collections/