Doom, woe, misery, how did we win the war? At least Mussolini made the trains run on time.
It’s the time that the UK has abnormally hot temperatures, and railways are slowed or suspended because of the wrong sort of heat on the lines, and out come the old tropes.
How did we win the war if our railways closed like this?
Various mayoral hopefuls spotting a bandwagon, dutifully jumped on board.
“Londoners have already suffered too much because of disruption on the train network. Network Rail needs to get a grip right now. It’s simply not good enough to delay trains because of the ‘wrong kind of heat’.” Sadiq Khan MP via Evening Standard
Well, as it happened, we won the war, and the railways DID close in the heat. We have always had problems with the heat.
“On Wednesday an accident arising from the effect of excessive heat upon railway metals happened to a train on the Great Western branch line from Ruabon to Dolgelly. Fortunately, the train was going slowly at the time and the passengers received nothing more serious than a shaking. The line however was blocked for several hours.” Birmingham Daily Post (Birmingham, England), Friday, June 28, 1878
Although developments in material sciences over the decades have improved things, railways are still essentially made up of long lengths of steel. And steel expands in the heat. Sometimes dangerously so.
“On account of the great heat, railway officials are keeping a sharp look out for the contraction of the metals. A case occurred between Crewe and Willaston on Wed afternoon. An engine rushed off the metals, fouling the main line.” The Bristol Mercury and Daily Post, Friday, July 6, 1894
Even today we cannot stop railway tracks buckling in the heat, and the best option is to minimise the effect, with good maintenance, and also destressing the tracks.
In the UK, railways are designed to work in a range of temperatures, with what is known as the “stress free level” set at 27°C, which may surprise you to learn happens to be the UK’s average summer temperature.
There will always be occasional heatwaves, but to raise the stress-free rating for railways to, for example, 30°C, would then reduce the range they can operate in during winter. And in the UK, we have more winter than summer!
So to avoid the occasional delay on a hot day could mean more delays on cold days.
One of the maintenance jobs on railways to reduce buckling caused by repeated temperature extremes is to de-stress the tracks, often by use of machines that pull or heat the tracks to release the built-in stress. This is a technique that was developed in the 1960s to deal with increased track buckling from the use of continuous welded rail (CWR).
Part of the reason for the use of CWR is that it offers long lengths of track without joints, offering passengers a smoother ride, and less banging on the wheels from the joints. While CWR is more expensive to lay than the older short lengths of track, it more than pays its way in reduced wear and tear.
Even with long lengths of continuous welded track, there will be some expansion joints to absorb some movement, and they can often be seen as wedge shaped chamfered gaps in the track.
The use of the diagonal slice in the track also reduces the noise caused by the train passing over them, which reduces wear, both to the track, and the trains. The use of continuous track is why the old distinctive regular bumping sound from trains running over gaps in short lengths of track is nowadays a fairly rare experience.
Minimizing delays is a combination of good maintenance to reduce the build-up of stresses, and being aware of where the stresses are likely to occur and usually slow traffic in those areas to safe levels, or cancel it entirely.
Increased track monitoring may make it possible to run trains and stop them only when the track becomes unsafe. However such trackside monitoring would be a costly solution to a problem that doe not happen all that often.
As with many weather extremes, it would be nice to know we can build infrastructure to cope with both heavy snowfalls and also heat waves, but the cost for a few days of benefit would be staggering.
Until then, the wrong sort of newspaper headlines will prevail.
Or maybe…
The railways should take the advice of a Mr Ellis Lever, who wrote to the Morning Post in July 1897 on the topic of hot carriages, proposing that the “roofs of passenger carriages be coated with a mixture of lime and buttermilk”, the effect being to turn the roofs white to reflect the heat of the sun.
Then again, maybe not.
I like the spirit of this article and it was an interesting read as ever, but it’s a little off, technically, in a couple of places. I could ignore this and do not mean to pick holes but I only hope what I have to say may be of interest to other readers or even the author.
As far as I know heating of rails for this purpose has not been done in the UK for several decades. As written, rails making up CWR are instead pulled when they’re installed but this is more accurately to stress them than to de-stress them. They are extended to the length they would be if the rail’s temperature was 27°C. This means that at 27°C they are stress free, below 27°C they are under tension because they want to shrink but cannot and conversely above 27°C the rails are in compression because they cannot expand. As written, a middle ground has to be found.
In jointed track the joints have to be lubricated and the gaps at the joints have to be set correctly to allow for expansion in hot weather.
Appreciate the clarification. Thanks
A fascinating article as ever. My art teacher at school was in Italy before the war and, according to him, the trains didn’t always run on time but you couldn’t complain about it.
I presume that for higher temperature pre-stressed track, then in a cold winter the danger is track shearing (and the sudden release of strain presumably could do some funky things to sleepers too), and possibly this would happen when a train was going over it adding more stress to the rail. Hence better for the track to buckle in (rarer) hot weather when a train isn’t going over it.
Also, let’s remember that the rails are not in shade, and that they can get to over 50 degrees in the sun, apparently.
Sykobee,
Yes, the main concern would be bolts shearing rather than the rails. Don’t take me as a source on this but I have heard that with the greater temperature range in Canada they have to stress to a high temperature for warmer months and stress to a lower temp for cooler months.
Additionally with reference to the article, although the idea of painted carriage roofs White seems odd, rails are often painted white to reflect some heat.
Rail Engineer had the same thoughts – http://www.railengineer.uk/2015/07/01/getting-hot-and-bothered-why-the-railway-doesnt-like-high-temperatures/
Some nice examples of just how far rail can expand in hot weather.