Tacoma Narrows Bridge
Leaning Tower of Pisa
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09
Tacoma Narrows Bridge
10
Leaning Tower of Pisa
In November 1940 , a physical phenomenon known as aeroelastic flutter caused the bridge to collapse just four months after opening . The warning signs were there during construction , when the structure was seen to move vertically in windy conditions . The main span collapsed in 40-mileper-hour wind conditions , but the sorry affair left the legacy of a boost in research in the field of bridge aerodynamics-aeroelastics .
Perhaps the most famous of all construction failures , but unlike others on this list , it was not too costly . A three-meter foundation and weak subsoil contributed to a lean of almost 5.5 degrees until preservation crews were called in to help lessen the instability . Today , the tower ’ s summit is more than 3.9 meters off-center , but at least this failure provides a good tourist photo-opp .
48 September 2014