Historical Memory and Engineering Failures

George Santayana, the Spanish-American poet and philosopher, once warned that "Those who do not remember the past are condemned to repeat it." This is especially true in the field of bridge building, where over the past 150 years dramatic failures have occurred at surprisingly regular intervals.

In 1847, the first major structural failure on Britain's expanding railway network occurred at Chester, England. The Dee Bridge, whose cast- and wrought-iron design followed common practice for the period, collapsed under a passing train, killing everyone aboard. Subsequent investigation revealed that the structure, the longest of its kind, simply pushed the limits of railroad-bridge engineering too far.

In 1879, the longest bridge in the world spanned the River Tay at Dundee, Scotland. Composed of many modest spans, the structure involved no radically new design concepts and seemed to be a mere application of proven technology. However, the force of the wind was grossly underestimated and worksmanship was inferior. As a result, the Tay Bridge, vulnerable in a gale, was blown off its supports.

In 1907, the longest span in the world was being constructed over the St. Lawrence River near Quebec, Canada. The bridge was of a relatively new type, known as a cantilever, which had become quite fashionable. Although it was only slightly longer than the highly successful cantilever bridge over the Forth River near Edinburgh, Scotland, the Quebec Bridge was so inadequately designed that it collapsed before it was completed.