Why the elegantly designed, Tacoma Bridge collapsed?
From the onset of design, certain dimensional proportions of the Tacoma Narrows Bridge were unprecedented. The bridges depth-to-span ratio was a startling 1:350m, almost a tenth of the 1:40m proportion of the ungainly Williamsburg Bridge, which was just close to what was considered the norm. Its ratio of width-to-span was just as equally frightening at 1:72m, which was far beyond that of the suggested contemporary practice value of 1:30m. Its sag ratio (which is important to the length and stability of a suspension bridge) was even at a low of 1:12m; yet this value was considered to be able to provide the necessary rigidity needed. Despite these unprecedented ratios, in all other areas, the span of the bridge met contemporary norms for live load and static wind pressure and was, therefore, approved for construction.
