At 1800 meters (about 5900 feet) long, the Tacoma Narrows Bridge in Washington State was one of the longest suspension bridges of its era. Upon opening to traffic, it was immediately called ‘Galloping Gertie’ because crossing it was akin to riding on a roller coaster. The ‘waves’ in the deck were as much as 6 ½ feet in amplitude!

It collapsed in 1940 during a storm, just four months after opening. The box girders under the deck, which were designed to give strength, apparently caught the wind. Lattice supports which allow wind to pass unhindered was one result. Complicated resonances caused by wind oscillations continue to be a challenge.

Other more recent bridge failures have been very costly as well. The sudden collapse of a 5-span New York Thruway bridge over the Schoharie Creek west of Albany, NY, occurred due to scouring during a flood in 1987 - the soil beneath the pier washed away and the concrete foundation settled and cracked. 

The Silver Bridge across the Ohio River collapsed suddenly in 1967 as a result of stress corrosion and fatigue in the carbon steel. 46 lives were lost. One result of this collapse was the creation of a new federal inspection standards (NBIS).

All these failures have been used to learn and improve - many techniques and materials improvements have been founded on failure.

 

Return to Top