Monday, 2 January 2012

Minimum Functioning – a case history

I quoted Professor Gordon in my last blog (Structures, or Why things don't fall down), and would like to do so again:

“The English railways were built straight and level across the rolling English landscape by the lavish use of cuttings and embankments and splendid viaducts of masonry and ironwork. All this engineering luxury depended upon supplies of capital and labour, both of which were plentiful in Victorian England. Conditions in America were totally different. The distances were enormous; capital was scarce; the wages, even of unskilled men, were high. In the Land of the Free, where every man was an amateur, skilled craftsman of the European type scarcely existed. Iron was expensive, but there was unlimited cheap timber. […]

“The railroads were pushed westwards as fast as they could be built and with a minimum of expensive cuttings and embankments. When conditions were suitable, the valleys were bridged by means of enormous timber trestle viaducts.”

The American railways could be built quickly and
cheaply because wooden trestle bridges were used very
extensively to save the cost of earthworks (c. 1875)

“These will always be associated, in tradition, with the American railways; a fair number of them survive today. Once they had been constructed, the American railways were vastly profitable – the Central Pacific Railroad is said to have paid dividends of 60 per cent – and they were soon able to convert many of their precarious trestle bridges to solid earth embankments by tipping soil from specially constructed trains until the whole wooden structure was encased in earth and could be left to rot away.”

To begin with then, what the Americans did was make the minimum change for the maximum effect; they did as much as possible at least cost first; they got their rail network to function, which means to say, they got the thing up and running. It is true that U.S. railroad engineers were prepared to take more risks with other people’s lives than their British counterparts, as evidenced by their reliance on ‘primitive bridges’, but as Rev. Samuel Manning noted at the time, “it is said that few accidents have happened from their use.” Significantly, the cost per mile of American railways was one fifth of that of English lines.

As soon as they were able, the Americans improved the standard of their rail network, for although the wooden trestle bridges were objectively or statistically safe, they were not subjectively safe. Samuel Manning again:

“The road is carried across valleys hundreds of feet in depth on rude trestle bridges, which creak and groan beneath the weight of the train. Anything apparently more insecure than these structures can hardly be found elsewhere, and I always drew a long breath of relief as I found myself safely on the other side. It is a fearful thing to look out of the carriage windows into the dizzy depth below, and feel that if the frail fabric were to collapse, as it seemed on the point of doing, we should all be dashed to pieces with no possibility of escape.”

The Americans began by developing their rail network to a minimum (or ‘rude’, or ‘primitive’, or ‘crap’) level of functioning. They did so by making the best use of the locally available resources. To all but the more hardened souls, riding on it was ‘a fearful thing’. Fortunately, not many of the passengers lost their lives during these early years, but as more people used the network, so more money became available to improve it.

The Americans understood very well that a pursuit of perfection can lead to paralysis. Oftentimes it is most appropriate to make the best of the circumstances as you find them. Obviously the Victorian approach was ‘better’, but as Professor Gordon points out: “British engineers were certainly not unduly cautious men; nowadays we should consider them rash.”

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