ACCUMULATION OF SMALL DISADVANTAGES. Henry Petroski's Pushing the Limits: New Adventures in Engineering provides a collection of his Engineering columns from American Scientist. Subscribers to the magazine are free to skip Book Review No. 49 and pass on buying the book. My post title deliberately distorts a chess maxim to highlight a central theme of the book, which is that great engineering disasters often arise from seemingly incremental tweaks to existing practice that appear to work well until seemingly unrelated difficulties with the tweaks cumulate in a catastrophic failure. The paper on the bonfire collapse at Texas A&M illustrates the dynamics. See p. 183.

The report shows the structural collapse to be a classic case of design evolution and engineering hubris contributing to what in retrospect appears to have been an accident waiting to happen. Bonfire tradition was to build on the successes of past years, but modifications made from year to year negated what could be learned from experience.

Such unobserved lessons included premature collapses of the fire and injuries suffered by previous fire-builders.

A similar pattern of apparently incremental modifications by Los Angeles water czar William Mulholland, a self-taught dam builder, led to the 1928 failure of the St. Francis Dam and at least 400 lives lost. (The essay appears surprised that in the 1920s, rural Californians were dynamiting the Los Angeles aqueducts. I'm being only mildly alarmist identifying the Lake Michigan - Mississippi River ridgeline as a potential flash point of a resource war.)

A number of the essays feature bridges, including, yes, the accumulation of small disadvantages, and the book has a short but instructive chapter on the collapse of the Twin Towers that advocates of the government-inspired-controlled-implosion fantasy ought be required to read, understand, and comment on why the chapter isn't sufficient evidence to end that fantasy for once and for all.

One chapter also addresses a number of engineering fantasies envisioned by Willy Ley in Engineer's Dreams. I recall works in a similar vein aimed at younger readers, published in a more ambitious or more optimistic era. Some of the projects are possibilities. Others are truly fantastic.