November 1940

摘要

This month marks the 75th anniversary of one of engineering's most infamous failures. The Tacoma Narrows Bridge, which (very briefly) spanned the Puget Sound in the US state of Washington, was opened in July 1940. Just five months later, the bridge was to suffer a catastrophic collapse, the iconic video footage becoming synonymous with engineering disasters. Christened the 'Galloping Gertie' by construction workers due to its vertical movement in high winds, the l,800m-long structure had a main span of 853m, the third longest in the world at the time behind the Golden Gate Bridge in San Francisco and George Washington Bridge in New York City. Although several measures were introduced to correct the flaws in the bridge's design, on 7 November Gertie went for her final gallop. In winds of just 40mph - relatively mild for the Pacific North West - the bridge began to sway and buckle dangerously. Aerostatic fluttering caused the central span to twist and contort, with the amplitude ultimately causing the suspension cables to fail.