Technofart

The Tacoma Narrows Bridge is a one mile long bridge stretching over

What doomed the bridge was the state’s lack of funding caused by the recommendations of East coast engineers, specifically Leon Moisseiff (helped design Golden Gate and Oakland Bay Bridges), who advised the state to save money by reducing the bridge’s girders from 25 feet deep to 8 feet deep, which caused the roadway to be less stiff and therefore more susceptible to wind-induced oscillation.

The collapse occured on November 7, 1940–the following is an eyewitness account by Leonard Coatsworth:

“Just as I drove past the towers, the bridge began to sway violently from side to side. Before I realized it, the tilt became so violent that I lost control of the car…

On hands and knees most of the time, I crawled 500 yards [450 m] 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.”

A new bridge was finished and opened on October 14, 1950, and is still currently in use today with no indications of any malfunctioning. It was designed to handle 60,000 vehicles per day, currently handles 90,000, and is projected to be able to handle 120,000 by 2020.

References and further reading:

Wikipedia article on the Tacoma Narrows Bridge

Thanks to Library Pulse for the photo

‘Learning Through Failure’ from Eide Neurolearning Blog

Televizzle.org’s Article on the Mythbusters’ Earthquake Machine that was tested effectively (relatively speaking) on a bridge that demonstrates the principle of mechanical resonance