There is a terrific website for learning about the tacoma Narrows Bridge disaster, at: http://www.wsdot.wa.gov/tnbhistory/Machine/machine3.htm (from the Washington State Department of Transportation). I especially like their analysis because they discuss the psychological “blind spot” of the engineers who designed the bridge — how the distinguished, accomplished engineers of the early twentieth century somehow ‘forgot’ the aerodynamic lessons of 19th century bridge designers. Combined with the need to understand the often complex torsional effects of winds on suspended structures, this oversight led to one of the most spectacular bridge disasters (and provides a terrific learning tool). Thank you, Washington State DOT!