June 2002

10 Technology Disasters

Continued from page 5

By Eric Scigliano

The Ashtabula Creek Bridge wreck

The United States' deadliest bridge collapse demonstrates the dangers in transposing what works in one material to a new, unproven one. In 1863, Cleveland railroad magnate Amasa B. Stone Jr. announced a bold advance in bridge technology-so bold it was never imitated. For two decades, the state of the art in American bridge design had been the reliable Howe wooden truss system, which added threaded iron upright supports to a classic structure of diagonal wooden trusses. The iron connectors provided more strength and eliminated the painstaking joinery of all-wood truss construction. So, Stone reasoned, why not go all the way and re-create the Howe design entirely in iron? Trusting too much in this newer, costlier material, Stone ignored both its potential for hidden weak spots and an essential flaw in his design: the bridge was assembled like an interlocking jigsaw, held together by pressure rather than the firm attachments of the wood originals; if one joint went, the whole structure would. Nevertheless, Stone proclaimed his 1865 creation "absolutely sound," and it stood for 11 years, even as its parts shifted. Then, on Dec. 29, 1876, as a passenger train crossed, an iron support with a hidden air bubble collapsed, the bridge tumbled down, fires spread from the train's tipped-over woodstoves, and more than 100 riders perished.