Modern railways

Tilting train near Penrith

Tilting train near Penrith

I’m not a steam fanatic, neither do I bother too much about trains. It’s the permanent way I like: the engineering, the way the railway interacts with the land: bridges, viaducts, embankments, tunnels. Of course trains matter to some extent, but what engages me is what they run on. I like to know about the design of junctions, track plans, the engineering that allows trains to travel round corners at speed. I’m curious about why and how some junctions are limited to 20 mph, or 50 or whatever. Some (a very few) are engineered for 125 mph. In my ignorance I used to think the reason why trains slowed down for bends was to stop them coming off the tracks. This is not so: they would need to be going extraordinarily fast to fly away like that. Speed is limited round bends simply for passenger comfort, the avoidance of the sort of g-forces that we (well I) like on big dippers.

When the railways were built in the 19th century, engine power was limited by men getting the coal into the burners. The surveyors minimized gradients by letting the tracks follow the lie of the land as much as possible. This means that in hilly areas there are lots of bends. This didn’t matter much then because trains could hardly get going fast enough for passengers to be discommoded. Think of the railway between Lancaster and Carlisle where it runs a sinuous course through the Lune gorge and over Shap. The uphill gradients limited the speed (imagine the firemen shovelling coal fast-forward like an old film). As for downhill, I suppose the trains were so slow at the summit that by the time they got up speed by, say, Penrith (northbound) or Oxenholme (southbound), they were past the most bendy bits.

Things are the other way round now. There is so much power available from the overhead wires, or the diesels, that going uphill provides little challenge. What limits now are corners, not gradients. And since the lines were built with lots of corners to ‘flatten out’ the gradients, we have a problem. In the new lines (London to Brussels and Paris, French high speed lines) the lines are pretty straight but the gradients are fierce. On the old lines, where it would be prohibitively expensive to straighten them out, the solution is the tilting train—like a motorbike going round a corner at speed. It’s quite exciting going through Penrith station at 90 mph (normal trains limited to 75) and seeing the station buildings leaning alarmingly. Isn’t the human mind wonderfully inventive?

I’ve taken out a subscription to Modern Railways. The only drawback is the political stuff and management jargon in it, but I still think it’s the railway magazine that suits me best.

One final thing: why do people these days talk about train stations. They are not train stations. They are railway stations. Aaaaaargh.

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