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Disruption due to high rail temperatures

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al78

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When we had the extreme heat at the end of July, I remember some disruption due to buckling rails and speed restrictions. We are currently having the hottest late August bank holiday weekend on record with temperatues reaching over 30C and still rising, yet I can find nothing about buckling rails this time. Why is it only some periods of hot weather cause this problem? I appreciate the end of July heat was a bit worse than this but I thought the problem occurred whenever air temperatures approach 30C.
 
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anme

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When we had the extreme heat at the end of July, I remember some disruption due to buckling rails and speed restrictions. We are currently having the hottest late August bank holiday weekend on record with temperatues reaching over 30C and still rising, yet I can find nothing about buckling rails this time. Why is it only some periods of hot weather cause this problem? I appreciate the end of July heat was a bit worse than this but I thought the problem occurred whenever air temperatures approach 30C.

I think you've answered your own question - temperatures at the end of July were much hotter than now.
 

iphone76

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When we had the extreme heat at the end of July, I remember some disruption due to buckling rails and speed restrictions. We are currently having the hottest late August bank holiday weekend on record with temperatues reaching over 30C and still rising, yet I can find nothing about buckling rails this time. Why is it only some periods of hot weather cause this problem? I appreciate the end of July heat was a bit worse than this but I thought the problem occurred whenever air temperatures approach 30C.

It may also be because there are fewer trains running over the weekend so no need to thin out the peak service. My line has had a blanket speed restriction for the past few days, but it is hardly noticeable compared to last month when the peak service was badly affected.
 

InOban

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Also the sun is much less strong now, we're only four weeks from the equinox, so railhead temperatures wouldn't be as high.
 

duffield

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I think you've answered your own question - temperatures at the end of July were much hotter than now.

Yes, there's a big difference between the current 30-32C maximum ('normal' top end temperatures that the rail network should generally be designed to cope with) and the July 36-38C maximum ('exceptional' top end temperatures which is pushing at/past the maximum the network is designed to cope with). I'm pretty sure the 36C we got in the Nottingham area was a record (lived here for 35 years), and it was the first time I've ever had a heat-related mains power outage. Looks like it's only a matter of time before we hit 40C peaks in the London area.

As the 'exceptional' becomes more 'normal' it's likely the network will need to move the rail expansion 'window' up by a few degrees. **

** From previous posts, it's clear there is a defined temperature range that the rails are expected to cope with, with a low point (below which rails might fracture due to contraction) and a high point (above which they may buckle) - so this 'window' may need adjusting as higher temperatures become more common. I would imagine that NR are already on the case and have been for some time, but I would also think it's not quick or simple to go around mass re-stressing rails for a different temperature range!
 

stj

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Same when the tar melts on the road never see that when I am in Italy.
 

londonboi198o5

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When we had the extreme heat at the end of July, I remember some disruption due to buckling rails and speed restrictions. We are currently having the hottest late August bank holiday weekend on record with temperatues reaching over 30C and still rising, yet I can find nothing about buckling rails this time. Why is it only some periods of hot weather cause this problem? I appreciate the end of July heat was a bit worse than this but I thought the problem occurred whenever air temperatures approach 30C.

What lines rails buckled in July that’s news to me?
 

duffield

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What lines rails buckled in July that’s news to me?

As far as I know there were no reports of actual rail buckling in July, but there were speed restrictions in some areas because the rail temperatures were in the 'danger zone' for *possible* buckling.

Presumably we were not in the 'danger zone' this time.
 

flitwickbeds

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The main issues last month were with overhead lines sagging due to the heat (resulting in pantographs pulling them down) rather than the actual rails.
 

MikeWM

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There’s a ‘track defect’ at Stansted Mountfitchet this evening causing fairly severe issues on the WAML. Coincidence, or heat-related?
 

AM9

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Yes, there's a big difference between the current 30-32C maximum ('normal' top end temperatures that the rail network should generally be designed to cope with) and the July 36-38C maximum ('exceptional' top end temperatures which is pushing at/past the maximum the network is designed to cope with). I'm pretty sure the 36C we got in the Nottingham area was a record (lived here for 35 years), and it was the first time I've ever had a heat-related mains power outage. Looks like it's only a matter of time before we hit 40C peaks in the London area.

As the 'exceptional' becomes more 'normal' it's likely the network will need to move the rail expansion 'window' up by a few degrees. **

** From previous posts, it's clear there is a defined temperature range that the rails are expected to cope with, with a low point (below which rails might fracture due to contraction) and a high point (above which they may buckle) - so this 'window' may need adjusting as higher temperatures become more common. I would imagine that NR are already on the case and have been for some time, but I would also think it's not quick or simple to go around mass re-stressing rails for a different temperature range!
It might not be achievable by just moving the temperature window up a few degrees. Climate change (or 'global warming' as the lay press like to call it) doesn't mean that minimum winter will be any different to what they have been for decades. Indeed, as the Meteorologists have been warning us for oveer 20 years now, they expect the weather to be much more extreme, unpredictable and that could include colder periods than have been experienced to date. If that is the case then it might start being necessary to adjust the track tension in the spring and autumn to prevent failures. Just another reward for abusing our planet. :)
 

ChilternTurbo

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This always puzzles me - I was using mainline trains around Barcelona last week and in the South of France in June and the ground temperatures were easily pushing 38c to 40c yet all services were running to time. Possibly a daft question but what are the differences between our track and OHL infrastructure compared to much hotter parts of Europe?
 

Peter C

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This always puzzles me - I was using mainline trains around Barcelona last week and in the South of France in June and the ground temperatures were easily pushing 38c to 40c yet all services were running to time. Possibly a daft question but what are the differences between our track and OHL infrastructure compared to much hotter parts of Europe?
Railway infrastructure is built to the weather standards of the country it is in. Barcelona and southern France frequently get higher temperatures than the UK and therefore they build their OHLE and rails to deal with them. We get a standard of 15 degrees C or thereabouts every year, and therefore we build the infrastructure to deal with those temperatures.
If we built the railways for high temperatures, they would cope with hot weather, but may not cope with lower temperatures. Building them to lower temperature standards means they only break once or twice a year when we get high temperatures! :)

-Peter
 

yorkie

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This always puzzles me - I was using mainline trains around Barcelona last week and in the South of France in June and the ground temperatures were easily pushing 38c to 40c yet all services were running to time. Possibly a daft question but what are the differences between our track and OHL infrastructure compared to much hotter parts of Europe?
There have been some recent threads you may find interesting:

https://www.railforums.co.uk/threads/continuous-welded-rail.185994
It’s still 27 AIUI.

I wouldn’t be surprised if there was some discussion about lifting it a degree. I’d expect SNCF to be having similar discussions too (they use 28C for the SFT IIRC)

https://www.railforums.co.uk/threads/heat-related-issues-25-july-2019-and-subsequent-days.186863/
How they cope in other countries is to have a higher SFT. In the very few parts of the world with wider temperature ranges than the U.K. (eg the Russian steppes), they will restress the rails for a different SFT each spring and autumn. Or put up with buckled rails.
 

al78

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It seems the network is more resiliant than I thought, I was under the impression that 30C air temperatures were when the problems started (it has reached 33C this weekend), but the responses here imply it needs to be a bit higher than that. If I understand correctly, the issue is most likely when high temperatures occur close to peak sun strength, from late May to July, and once we get into August, the risk drops off as the sun strength is quickly dropping off.
 

al78

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"In the very few parts of the world with wider temperature ranges than the U.K..."

I don't understand this statement. The UK has a narrow annual range of temperature*, that is why it is called a temperate climate. Every mid-latitude continent will have greater temperature ranges than the UK because they are affected primarily by continental, not maritime air masses, cold in winter, warm/hot in summer.

*SW Ireland has one of the worlds lowest annual temperature ranges outside the tropics.
 

Peter C

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"In the very few parts of the world with wider temperature ranges than the U.K..."

I don't understand this statement. The UK has a narrow annual range of temperature*, that is why it is called a temperate climate. Every mid-latitude continent will have greater temperature ranges than the UK because they are affected primarily by continental, not maritime air masses, cold in winter, warm/hot in summer.

*SW Ireland has one of the worlds lowest annual temperature ranges outside the tropics.
I think that statement may have been including the high temperatures we have seen recently, but I'm not sure. But yes, by itself it makes very little sense!

-Peter
 

Greg Read

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This always puzzles me - I was using mainline trains around Barcelona last week and in the South of France in June and the ground temperatures were easily pushing 38c to 40c yet all services were running to time. Possibly a daft question but what are the differences between our track and OHL infrastructure compared to much hotter parts of Europe?

Why do people go on long winter breaks to Spain? Yes, they have a warmer winter, snow is almost unheard of, also the frequency of trains bashing the track is a lot less too, some Main Lines in France may only see 4 or 5 a day !
 

Mojo

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Why do people go on long winter breaks to Spain? Yes, they have a warmer winter, snow is almost unheard of, also the frequency of trains bashing the track is a lot less too, some Main Lines in France may only see 4 or 5 a day !
That argument has already been debunked in the threads linked to above,
there are plenty of parts of the world with hotter summers and colder winters than the UK, whilst Spain is not one of them, much of the populated areas of North America experience this.
 

GB

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The main issues last month were with overhead lines sagging due to the heat (resulting in pantographs pulling them down) rather than the actual rails.

No, the rails were also a potential problem. This is why all freight in the Anglia region and some parts of the London North Eastern region were not allowed to run between 1200-2000. Quite rare to effectively close off an entire route to freights like that.
 

ChilternTurbo

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Railway infrastructure is built to the weather standards of the country it is in. Barcelona and southern France frequently get higher temperatures than the UK and therefore they build their OHLE and rails to deal with them. We get a standard of 15 degrees C or thereabouts every year, and therefore we build the infrastructure to deal with those temperatures.
If we built the railways for high temperatures, they would cope with hot weather, but may not cope with lower temperatures. Building them to lower temperature standards means they only break once or twice a year when we get high temperatures! :)

-Peter


Thanks for the interesting responses. It of course makes sense to build infrastructure that's appropriate for the climate it's going to be used in. I do think with increasing temperatures and extremes of weather associated with climate change, that specifications of future and replacement OHLE and track will need to take this into consideration...
 

Peter C

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Thanks for the interesting responses. It of course makes sense to build infrastructure that's appropriate for the climate it's going to be used in. I do think with increasing temperatures and extremes of weather associated with climate change, that specifications of future and replacement OHLE and track will need to take this into consideration...
You are welcome. I can't really give any further information due to my lack of knowledge in this subject. :)

-Peter
 
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