On November 7, 1940, the first Tacoma Narrows suspension bridge collapsed due to wind-induced vibrations. Someone was fortunate enough to be filming at the time; many of you have probably seen the remarkable footage. Situated on the Tacoma Narrows in Puget Sound, near the city of Tacoma, Washington, the bridge had only been open for traffic a few

months. Well, they’ve almost done it again, this time with a pedestrian structure. London’s wobbly Millenium Bridge was closed on its opening weekend last month (before it frankly collapsed!). It seems that soldiers on the march know that they have to break step before crossing bridges to avoid a version of this problem. New Scientist