Disasters · Washington

The collapse of the Tacoma Narrows Bridge

November 7, 1940
Tacoma Narrows straight, Washington
The Tacoma Narrows Bride collapses due to structural failure following high gusts of winds

The bridge, nicknamed Galloping Gertie due to its intense movement during windy conditions even before its collapse, was a suspension bridge nearly 6,000 feet (more than 1800 meters) in length making it the third longest suspension bridge at the time of its completion.

Leon Moisseiff, the bridge’s designer, designed the bridge to be the most flexible ever, and engineers believed the structure would be safe. The engineers, however, did not take aerodynamics forces into account. (At the time, wind forces were often not taken into consideration when designing and engineering buildings and bridges.)

The bridge swayed often during construction and after it was opened to the public on July 1, 1940. On November 7 of the same year, high gusts of wind reaching 40 mph (64 km/h) rocked the bridge. Wind instability caused changes in air pressure and, by extension, vortices which swirled around the bridge, causing it to lift, descend, and twist until it finally broke. At 11 a.m., a 600-foot section of the bridge tore free and fell nearly 200 feet (60 meter) to the waters below.

The only life lost was that of a dog left in a car. Though a rescue attempt had been made, the dog was too terrified to leave the vehicle and bit one of his rescuers. A replacement for the bridge was delayed until after World War II, and was completed in 1950.

A video of the famous collapse can be seen on YouTube.

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