Something like forty bridges a year fell in the 1870’s—or about one out of every four built.

From The Great Bridge: The Epic Story of the Building of the Brooklyn Bridge by David McCullough.

I think it would be wonderful for people, in either high school or college, to have a single semester of engineering history. Engineering is science and history and economics and knowledge and politics all rolled into a ball of trade-offs and compromises. These two disasters occurred in 1876.

Furthermore, in the back of everyone’s mind were two very recent sensational tragedies. On the night of December 5, the Brooklyn Theater, built by William Kingsley’s construction company and owned by his partner, Abner Keeney, had caught fire and 295 people had lost their lives, many of them because the balcony had collapsed. It was the worst disaster in the city’s history. Then on the night of December 29, one of the worst railroad disasters of the nineteenth century occurred when a bridge failed at Ashtabula, Ohio. The bridge was just eleven years old, a wrought-iron truss over a seventy-five-foot gorge. When a train pulled by two locomotives started across it in the middle of a snowstorm, the center span gave way. It was thought that the metal had failed somehow. Eighty lives were lost.

The newspapers were angrily crying for an explanation. Harper’s Weekly in its latest issue asked:

Was it improperly constructed? Was the iron of inferior quality? After eleven years of service, had it suddenly lost its strength?…Was the bridge, when made, the best of its kind, or the cheapest of its kind?

The chief engineer of the railroad, a man named Charles Collins, who had had nothing to do with the design of the bridge, but had examined it frequently and conscientiously, tendered his resignation, then committed suicide.

The Ashtabula bridge had not been cheaply built and the iron had not suddenly lost its strength in some mysterious fashion. As subsequent investigations would show, the bridge probably went down because the derailed wheels of several cars ripped the bridge floor, causing a violent pull of a kind the truss had not been built to withstand. But the idea of bad (cheap) metal failing had been planted in the public mind.

The Wikipedia account is here.

McCullough adds in a footnote:

The Ashtabula disaster was only the worst of hundreds of bridge failures of the time. Something like forty bridges a year fell in the 1870’s—or about one out of every four built. In the 1880’s some two hundred more fell. Highway bridge failures were the most common, but the railroad bridge failures received the greatest publicity and cost the most lives.

Every few years vested interests launch a campaign to try and gin up a panic over crumbling public infrastructure with a view to passing hundreds of billions in spending. It is true infrastructure needs maintaining and it is true that in some places and at some times politicians are horrible stewards of public assets, allowing them to fall into decrepitude to the endangerment of public safety. But the answer is a steady discipline of investment in maintenance. The big packages of billions are simply a mechanism for grifters to pick the pocket of the public.

But McCullough reminds us of a period when the basic problem wasn't so much incompetence and corruption (though those were serious and real). We simply did not know all that much about the rudiments of engineering before we rushed into mass engineering of infrastructures.

I recall reading an account of the life and works of the great Victorian engineer Isambard Kingdom Brunel. He was one of those engineers who immediately took concepts from the lab or small field trial and deployed them into major projects. Sometimes with spectacular success and sometimes with financial and operational disaster. But on balance he moved humankind into material modernity with spectacular speed and safety compared to the past.

His first major ship, the Great Western was one such project. A giant for her time, she was a transatlantic side-wheeler.

Steam engines were new technology, industrial grade iron manufacturing was new technology, macro-engineering materials were new technology. While commercially and operationally successful, the striking thing to me reading abut the Great Western all those years ago was the low pressure for the boilers which only produced 750 horsepower. Why the low PSI? Weak iron for the boilers.

By comparison, a Suburban SUV produces about 200 horsepower. A Nimitz class aircraft carrier produces 260,000 horsepower.