Why rails buckle in Britain | Hacker News Reader

Why rails buckle in Britain

networkrail.co.uk

278 pointsscrlk244 comments

This drove me down a rabbit hole, so I thought I would share.

Track used to be separate pieces (seemingly before 1950), but they are now continuous welded rail [1][3]. This was done to allow trains to go faster, and lowers maintenance on the trains. This confused me because trains go "clack clack clack" - I guess that's foley now.

However, it means track is more prone to buckling, since there aren't any expansion joints, like we have on bridges.

Slack is added/removed from the rails by stressing the track during installation [2].

They heat (or mechanically stretch) the track to the length at a chosen "neutral" temperature. Then they install the track. This allows them to calculate the max expansion and contraction the track will see and offset those forces with the sleepers (horizontal forces?) and the ballast (vertical forces?).

The rail can still buckle - this is engineering. If the ballast fails, or the temperatures exceed the maximum allowed for, then it will buckle. It also looks like it must be continually destressed by going along the rail, cutting it and re-welding it? [4]

[1] https://en.wikipedia.org/wiki/Railway_track#Continuous_welde...

[2] https://en.wikipedia.org/wiki/Rail_stressing

[3] Thermite track welding: https://www.youtube.com/watch?v=5uxsFglz2ig

[4] https://www.nzherald.co.nz/nz/peter-calder-old-methods-keep-...

CWR is common to reduce noise and bumps. The latter in particular is really important at high speeds, because the feel of a bump to a rider is a lot worse.

It should be noted that whether rails are continuous or not depends a lot on the country and the region. There are still many places around the world where you'll find tracks made of separate pieces. For example, Russia has around 10,000 kilometers of track like that (out of 85,000 km total).

Much of the US rail network is still piece-rail; it's only CWR when replaced, because most rail-miles in the US are freight-only, and almost all are freight-primary.

Russia sees extremes of both heat and cold. That may play a part in deciding to use separate rail piece.

I don't think so. It was all separate historically up until 1960s, but then gradually updated to continuous as budgets allow.

Thing is, even aside from passenger comfort, you also get about 5% less friction from CWR, which translates to more fuel efficiency. And 5% might not sound like much, but when most freight cargo goes by train, and distances are in thousands of kilometers, it adds up pretty fast. Ditto for reduced maintenance on the tracks themselves, which is especially handy for those long tracks going through largely empty areas.

Yeah trains haven’t clack clack clack for a long time now. Possibly as much as 20 years for the lines I’m on.

Buckling at high temperature is better than fracture at low temperatures. I used to do research in this area. The "holy grail" technology would be a non destructive way to infer the "neutral stress temperature" of continuously welded rail that has been already installed in a quick and non destructive way. Saw lots of weird hopeful technology prototypes based of measuring the hysteresis curves of induced magnetism in the rail, idea being that the stress would have some effect on the magnetic domains. Never worked in the field AFAIK. Here in Australia they will get hoses out on hot days desperately trying to cool the rail down to stop it buckling.

> Here in Australia they will get hoses out on hot days desperately trying to cool the rail down to stop it buckling.

Have you got anything to show that?

Never seen or heard of that in NSW, and not heard of any track buckling issues during summer, either.

I've only found mentions online about spraying post buckling during repairs, but pre-emptive spraying does (did) occur. You will hear about speed restrictions on hot days to avoid buckling.

https://www.researchgate.net/figure/Buckling-of-a-railway-tr...

Yeah I have never seen anything like that in NSW either - anyway on 38°+ days one would have to spray continually anyway, and there’s no way you could do that along a whole rail line in a country that routinely experiences droughts and water restrictions in the summer.

It wouldn't help for rail already installed, but I wonder if you could insert two corrosion-resistant pins in the rail at some standard distance apart. The pins would be installed when the rail is at its "neutral stress temperature". Then you could use some Go/No Go gauges to quickly check if the rail has expanded or contracted. By measuring the distance you could get a more accurate assessment of the stress state. The accuracy required might be too much, though.

It's an interesting problem. It's simple in theory, but may not have a perfect solution.

Part of the problem is that even the state of stress at installation isn't known very precisely. I basically did some pre work on a similar idea. Working through if you could track the displacement of sleepers could you figure it out. Problem is the extension in nominal range is linear and there isn't a simple way to work out where zero is.

My weird idea would be if sound waves would travel differently down the rail dependent on temperature. Although, the rail is likely not uniform enough to detect the differences?

I found a device that is in use - Verse[1]. It claims to be able to measure the neutral? Although my read says the rail must be below neutral, and therefore under tension, to determine what the neutral is?

They unclip the rail and then lift it with a known force? I guess that lets them measure the tension and lateral forces on the rail?

[1] https://www.pandrol.com/us/product/verse-rail-stress-managem...

https://www.youtube.com/watch?v=Qg9vn50ZOdo

https://www.youtube.com/watch?v=WbNzhMsUOwA

Railway buckling video: https://www.youtube.com/watch?v=jJeiYaSFCf0

Verse PDF: https://railway-news.com/wp-content/uploads/2020/02/VERSE-Te...

That's interesting. Unclipping the rail is a bit of an exercise though. Makes sense that it must be in tension, otherwise it would move on unclipping. I guess they just measure it in the morning. All these types of devices are less practical as soon as you have to disrupt services to do the measurement. Your idea of the measuring the dynamic response is something that has been investigated. Modal testing is very common (using accelerometers on the rail and a force measuring hammer). The effect would depend on the boundary conditions of the rail (so basically something that varies from site to site) so you would need to track how it changes over time. The engineering problem is how to collect this data easily.

The neutral temperature is 27C, we may have to follow countries further south in setting it higher.

Sydney Australia uses 35°C

Iron ore ops in the Pilbara, (northern) Western Australia use 40°C

From an accident report:

> The area surrounding the 67 km point had been subjected to several maintenance activities, including a few days before the derailment. The records showed that a length of rail was installed at about the 67.150 km mark when the rail temperature was about 65°C

> According to BHPB, the stress-free track temperature was 40 °C. This specification was based on midpoint average minimum and maximum temperatures expected for that time of year (summer).

https://www.atsb.gov.au/media/5775153/ro-2015-023_final.pdf

Ontario suggests their rails are designed for 30C to -30C: https://www.cbc.ca/news/canada/hamilton/headlines/metrolinx-... (2016)

Addressed in the post:

>Why don’t we replace all our rails with ones stressed for higher temperatures?

> <snip> ... there would be the risk of increased tension on the rails in the winter.

You're correct that the rail needs to continually have its stress managed. This could be cutting the rail and adding a new piece, or removing a bit. This is a fairly labor intensive and costly process so the railroads were very interested in coming up with a way to determine when a buckle or break was most likely.

Buckles and breaks were most common just after a train had left a section of track. The normal approach was to issue slow orders when the temperature got too high (buckle) or too low (break). So there was a lot of interest in finding more accurate ways to determine when slow orders were necessary and to optimize when to add/remove rail.

AFAIK this problem is still outstanding. The product I worked on years ago never quite succeeded. Railroads are a harsh environment.

maybe you could have a automated drone "chaser" caboose that follows a train a few miles behind looking for buckles and breaks.

For suburban networks signals will go to danger if the rail breaks and interrupts the track circuit

Breaks are "easy" to find, the problem would be buckles where the track is still "connected" but it is one rail is no longer equidistant from the other rail.

Only if track circuits are used in the first place. Modern installation tend to prefer axle counters, and even with track circuits some designs use only one rail for the track circuit and therefore wouldn't be able to detect breaks in the other rail.

Train carriages used to go ca-chunk-ca-chunk, ca-chunk-ca-chunk, ca-chunk-ca-chunk. Each carriage has two bogies and each bogie has two pairs of wheels on axels; the first ca-chunk pair was the forward bogie, the second the rearward bogie.

It was as recent as the 1980s in Ireland, I remember the sound when travelling by train as a kid.

Yah. But you can have these instead [1] https://de.wikipedia.org/wiki/Feste_Fahrbahn#/media/Datei:Oe...

(right track, above middle of picture) Not only on bridges.

AFAIK this is the way to go with any sort of HSR, "Feste Fahrbahn", https://en.wikipedia.org/wiki/Ballastless_track or whatever. I remember them even from the early 80ies, asking people about what that is, and why?

Edit: I see your [1] has a similar picture for an "expansion joint", but it looks functionally different, because not "seamless". With the stuff I know there is only expansion outwards, while there is almost no gap on the rail itself.

> This confused me because trains go "clack clack clack" - I guess that's foley now.

They still seem to go clack clack on some bits.

> When a track is made up from short rails bolted together, we leave small gaps between each one so that expansion doesn’t cause a problem. [0]

They seem to use both long welded pieces and short gapped pieces, i'm guessing they are just selective where they use each. Anecdotally, trains seem to go slower on the clackedy clack bits...

Speculation: I wonder if gapped sections are more resistant to failure IF they are used at slower speed? i.e long welded sections reduce maintenance at high speed; but gapped sections lack lateral temperature stresses, so IF they are used at a slow enough speed they could have very little stress. If so it's possible they use them on track close to stops, busy junctions, or track which is simply in a difficult area to carry out repairs on... essentially anywhere that track repair work will cause more problems than average and it's worth having slower trains on. Correction welcome.

[0] https://www.networkrail.co.uk/running-the-railway/looking-af...

What many countries started doing is painting rails white. I believe that is also happening in the UK. I believe they started doing that in Italy with good results. This is what the painting process looks like in Austria in a trial project: https://youtu.be/GBMWHAkk6xM?t=52

So einfach, so wirksam

Unable to find guidelines or comment from the mods, but HN’s comments are in English, please use English unless it is a comment in English explaining a non-English term.

(Dang, please clarify HN’s position on non-English comments; believe I recall seeing this before, but unable to find guidelines or comment from you. Thanks.)

EDIT: Related comment from Dang on use of non-English submissions:

https://news.ycombinator.com/item?id=27571809

I agree completely with "comments in English, please". but despite not learning any German for over 50 years, I came up with "One think works", which is not too far off!

"So easy, so effective" seems like the most appropriate translation in this case

Submissions have to be in English. The problem with the GP comment is not that it's not in English, it's that's it's tropey and unsubstantive. Just flag bad comments and move on.

Kannitverstaan! Was Du saggn?

Submissions are community property, so to speak, so the rules are stricter for those.

There's a lot more room for individual expression in comments. If someone's quoting a saying or making a quip that's best expressed in another language, that's fine. If they're consistently posting in a way that most people here can't understand, we'd ask them to stop.

Understand and agree, thanks for taking the time to respond!

From a linked page:

"We paint certain parts of the rail white so they absorb less heat – and expand less. Typically, a rail painted white is 5°C to 10°C cooler than one left unpainted."

Looks surprisingly laborious if this Twitter video is to trust: https://twitter.com/networkrail/status/1547986150723244032

You’d think they could make a robot to paint the rails but then again, the rails on the things that vehicles are supposed to be riding on!

Perhaps you could make a device that rides on one rail while painting the other one. Flip it around and do the other side when you’ve done the first pass.

or just paint behind the robot

And use a pencil instead of inventing a pen that works in zero gravity.

The pencil introduced graphite dust into the air that caused electrical problems.

This is why astronauts use a pen. Sometimes the "cheap and simple" way has side effects that are more harmful than the original problem.

Oil pencils and wax pencils are a thing too.

They are, and the Soviets stopped using them because

- The paper peeled away is a fire hazard

- The oil and wax writing smudges and is a terrible way of writing

- The floating bits of paper from sharpening the pencils was a mess and since they float, got in people's faces.

Generally those are terrible ideas too, especially compared to a $100 for a pen. It's really not that much compared to every other cost.

What about mechanically advancing wax rods? The question isn’t whether the unit price of a super-pen is less than that of a consumer-waxpencil, but rather the R&D cost of the super-pen vs that of a supposed super-waxpencil.

NASA didn't spend any R&D on it as it was developed by a third party, so that point is moot as the answer is $0.

https://www.scientificamerican.com/article/fact-or-fiction-n...

And Russian space station (while they had one) was notorious for repeated fires.

Probably that approach to safety was cause for it.

How would this be any better then the video? It would also be much more expensive and complex then what they made.

The GP's video shows them using a spraying train car to do it much, much faster. It still has people riding on it and walking alongside, but sure looks more efficient.

Meanwhile, I notice that all the replies to the UK video are people complaining about the rail system reducing headcount and mocking the idea that this task could be automated.

For context, a bunch of UK rail staff have been striking lately and one of their demands is no efficiency improvements or compulsory redundances. (They also want a substantial pay increase of course.)

If you read anything about their demands, you will discover that from this year their contract is changing to require more hours at the same pay, so they are literally being given a paycut. In every other industry that would be illegal, but rail workers are expected to just suck it up and be grateful that they even still have a job, right? They protest compulsory redundancies because they know exactly how the British system works - a lot of people will be fired and the rest expected to just pick up the slack and work more hours, without any improvement like automation.

And among other things changes like not being paid for their commute when doing overtime(which was paid for previously), at the time when petrol has crossed £2/L around the country.

Are pay cuts illegal in UK? Wow, that’s insane.

Why is that insane?

Why is it insane? Maybe I should have clarified - your employer cannot cut your pay without a very good reason and you have to agree to it. In general it's a very tricky process legally, just like letting someone go - you need to make sure it's done correctly or you will lose in court. They cannot just say "from next month you will work extra 2 hours a week at same pay". Like....no? That's not in the employment contract we have signed, it binds both sides. And yet that's exactly what is happening to rail workers.

Your clarification makes more sense -- I also consider reduction in pay to be equivalent to firing, a piecewise one. I understand that it means that has to follow all rules about firing people, and that much I also find reasonable. At the same time, I find the rules about firing commonly found in Europe as wrongheaded, but that's not my complain above, which is about "illegality of pay reduction".

Do we count price increases on healthcare provided through an employer as a paycut? If so, everyone I know has been getting paycuts for years even ignoring inflation.

None of the media coverage I've seen or can find seems to mention this supposed paycut due to more hours at the same pay, including in really sympathetic outlets like the Guardian which describes their demands as being exactly what I claimed. In fact, the only change to terms I can find anywhere that even vaguely resembles that is that maybe some staff will no longer get the same generous overtime multiplier on Sunday, and that's from the literal World Socialist site which is vague enough in their wording that I suspect they might be playing sneaky word games again. (They're... not the most trustworthy source.)

Such automation will be banned in the UK. Painting things has to be done by hand. Union rules. No unauthorized mechanization! Spray cans are untested technology and are unsafe. Spray paint is worse for the environment and workers health. Besides, painting by hand is better for morale.

Painting will obviously have to happen at night (double pay), and is risky work (double pay again). Oh, and we can't do more than 3 hour shifts because it involves bending down. And we'll be needing a minimum crew of 8 - 1 painter, 1 safety expert, 1 signalling expert, 1 electrics expert, 1 spotter, 1 paint quality expert, a foreman to lead the team, and a union rep to check everything is done according to the book. Oh, and wherever the work is being done more than 15 minutes from a toilet, we'll need a mobile toilet booked and installed, as well as a break room. If any of those people are missing or late, we'll cancel the work and retry in 3 months.

Railroad deaths and injuries per capita are much lower than in the USA. I'd say the unions and RAIB have done a pretty good job at improving safety standards.

Ah, but railroad workers in the US are also part of a union/unions, with arguably even more rules and regulations and very averse to technological advances, since it reduces the need for manual labor. So yeah USA would have more deaths because everything is manual and archaic, whereas in the UK you have things like the DLR, it could never happen in the US.

The DLR is only automated because it's brand new. It replaced nobodies job. And even that was a real fight to get and caused lots of strikes.

Of course, but try to add an automated line to the new york subway.

That would free the people to do the job of "conductor", "nanny", security, and cleaner to make that mess a less icky experience. Morale boost!

TfL brought level 2 GoA to a few Tube lines. In the US newer subway systems are already at that level. DLR is GoA 3, and a few smaller lines in the US (e.g. Las Vegas Monorail, Miami's thing, pretty much all airport people movers) are Level 4.

Yes, newer ones don’t have the same problem, since they are not held back by the rules of a union. Sadly those are few and far between, and I haven’t heard of a new railroad line since the yet to be finished CHSR, though can’t blame that one on the unions.

Dude. What the fuck are you on about?

BART and Muni are both union shops. I don't know if SMART is but it postdates the HSR proposals.

As someone who lived through Muni's transition to SelTrac (the system that underpins DLR and I think some of the Tube lines) I can say the union was not the problem. The technology was unreliable and eventually abandoned by Alcatel/Thales. GoA 4 stuff is only viable along small, low ridership stretches of track. If you knock the level of automation down a peg or two it's a lot easier to scale up to busier/larger systems.

This has been downvoted, but in my experience of 10 years of working in the UK rail industry, this is pretty much spot on.

> we'll be needing a minimum crew of 8 - 1 painter, 1 safety expert, 1 signalling expert, 1 electrics expert, 1 spotter, 1 paint quality expert, a foreman to lead the team, and a union rep to check everything is done according to the book.

Hah! Typical free market libertarian approach that cuts corners. You can't just go out and start painting stuff matey! What about the viability study? Someone needs to build a model of the processes, and conduct a pilot time and motion study. People won't just accept white rails without consultation. Where's the perception management and transformation campaign to make sure the new white theme is on message and brand aligned for Railtrack? You'll have to add at least 1 lawyer, 1 community liaison officer, 2 PR people, an advertising account executive...

> we'll need a mobile toilet booked and installed

Toilet? Pfff. You can't just go out and stick up a toilet....

while this isn't without merit, I consistently see that individual workers are much more concious of quality of their work and safety/reliability of the end user than the management is.

We've had many industrial accidents, from Bhopal's disaster to Boeing Max, thousands of people died, and all of them were caused by management meddling where they shouldn't. none of them were caused by unions

Does not even matter that majority of the rail in the UK does not operate at night.

For all you doubters, this is how it works. And talking of breaks, if a manager says anything to the lads, even non-work related, they're allowed to start their break again.

It's even spraying in front of the train car and then apparently rolling right over it without much trouble (although I note some white paint on the wheels).

I don't think anyone is expecting the paint to stick to the rolling surface of the rail for very long, but that (on a track with regular usage) gets polished by the passing trains, so it's reflective anyway...

Of course that is not a problem.

What needs to be painted is the sides of the rail, the top - even if painted in the process - will return to lucid metal as soon as the next few trains pass on them.

Usually small trucks (Unimogs adapted to rail use) or small convoys are used, see:

https://scalaenne.wordpress.com/2016/07/30/binari-bianchi/

Painting vehicle and robot likely cost pretty much the same. And with vehicle you don't really need to think about all of the nitty gritty details of autonomous operations or regulations.

This is an easy problem to solve. You just have the paint mechanism at the back of the vehicle so it paints after the wheels have moved over the track. Kind of like the reverse of the plough at the front of the train that some networks (not U.K.) have to clear the track before the wheels pass over it.

Do it from the back end while it moves forward?

It still blows my mind that the color of something makes such a difference.

I suppose you could as well polish them very well, but I think that will last shorter time than paint.

a tricolour dog or cat that's been sitting in the sun is how I discovered this as a child!

How did you decide what 3 colors to paint them with for the test?

It sounds like a natural experiment to me - genetics decided the colors (I'm guessing black, white and brown: colors commonly found in multicolored cat & dog breeds)

Wait until you hear about how much money we could be saving if roofs were white instead of the typical dark gray. (Locale: en-US)

Wait why aren't roofs white then?

Many newer roofs are white. For example, EPDM roofs are all near-white.

Meh, my EPDM roof is black.. I think you’re thinking of TPO?

If you live in the north, it's so you don't have roof collapses in the winter due to snow buildup.

If you live in the south, it's because people think there isn't good roofing materials that can be lighter colors. Those people are wrong.

Once the snow is covering the roof the color can’t matter? This would only have a marginal effect on very mild snow to melt it before it accumulates. Snowy days also don’t have much sun to catch to begin with, clouds ya know. No, roof collapses are prevented by stronger and more sloping roof.

I can tell you're not from the north. Snowy days aren't dark and cloudy. You'll wear sunglasses sometimes. Dark roofs absolutely help melt snow. The snow starts melting near the gutters and then climbs upward. The snow also sublimates. When it gets really cold, clouds can't form so there are a lot of bright days without a cloud in the sky.

The north could (and is!) solved by metal roofs that are white or light colored and steep - steep enough that snow slides right off.

Because they produce glare for neighbors. Also tradition. Mirrors would be even better, but apart from expense and weight, worse for anyone in the path of the glare :-/ [edit: reply comment to this says mirrors wouldn’t actually be better]

But, for example, California is requiring light roofs and other mitigating issues, so there is some progress.

BTW if you do decide to paint your roof (or any other external surface) please use TiO2 paint as the UV from the sun will then cause it to break down pollutants like NOx and greenhouse gases like methane.

Mirrors have low emissivity. While they accept a bit less heat, they will hold on to it more than something with white paint (which can have pretty good emissivity) and will thus get hotter.

Thanks, that’s interesting. Al is a pretty good IR reflector, and I believe most common mirrors these days use it as the reflective coating. Is the glass the problem?

Given that window glass can get damn hot when exposed to strong sun, and situating a perfect reflector behind it would presumably double the effect, intuition leads me to guess that yes, the glass would be a problem.

Cultural norms are really hard to change. There is no reasonable world in which businesspeople in the US south and southwest should wear suits and ties. But if they didn’t, they would not be taken seriously in our culture.

They are in many parts of the world. The reasons why they aren’t in other parts of the world are many, but they include the fact that bitumen as a petroleum byproduct has been cheap; other traditional roof materials used in Western Europe are also naturally fairly dark; in cooler climates heating has historically been a more pressing concern than cooling; people migrating from said cooler climates have not bothered to adapt their construction methods to local conditions; AC powered with cheap fossil energy has been seen as a silver bullet; people choose to avoid upfront expenses even if that means suffering in the future; cooling is rapidly becoming a concern even in said cooler climates, but adaptation lags behind because people are surprised that the climate change is actually now their problem and not some future people’s problem…

There is such a thing as white bitumen, and Obama's Nobel-laureate Secretary of Energy Steven Chu had suggested we adopt it.

Just built a house in Ireland (moved here from California) and have been very glad we ignored basically all the advice people wanted to give us and went for things that make it easy to cool. High ceilings with roof windows to vent heat have made the last couple days much more pleasant. Really glad it's wood and we're not dealing with all that thermal mass people here seem so enamored of.

I also have a 200 year old stone cottage and when it gets hot it stays hot for a very long time (same for being cold).

Thermal mass makes sense if exposure to heat can be carefully controlled, in a manner consistent with solar passive principles. Ideally this would be in the form of concrete floor/brick wall behind a glazed and shaded south-facing window (northern hemisphere) in an otherwise well insulated house.

In practice, it’s generally better to just have a well insulated house in the first place. (Passivhaus being the attainable ideal.)

True, and thermal mass is amazing if you have a lot of giant rocks and use them to soak up sun and keep fruit trees warm at night, allowing you to grow fruits normally suited to much warmer climates.

My experience was mostly old brick buildings in Dublin (old enough to not be cavity wall) and having all the heat they soaked up during the day radiated back at you at night.

I plan to add retractable awnings over the windows that get a lot of sun at some point too; they can make a big difference.

And, of course, trees! Deciduous trees give you shade in the summer and kindly drop their leaves so you have light in the winter. They're amazing!

Thermal mass can definitely be useful when you don't have air conditioning. Most of the older building in countries like Peru had thick walls (as well as tall ceilings) and were far cooler than outside during the day since the thermal mass effectively buffered the indoor temperature between night and day.

True, I think I'm just a little grumpy from years of boiling hot apartments in very old buildings.

The roof of the apartment building where I live is silvery-white.

It makes totals sense. I also suppose that many people who own single-family houses would not do that, mostly because it looks odd. Looking odd is something that makes people uncomfortable.

When you find a way for a light-colored roof to look cool while also not costing an arm and a leg, people will gladly adopt it. This happened to solar panels when they started to look well and also signal wealth and care of the Earth.

This is also why I paint my CPUs and GPUs black.

It’s easily relatable, compare wearing a black vs white t-shirt a warm sunny day.

[1] https://duckduckgo.com/?q=la+painting+streets+white

The same thing is done to roofs in hotter climates; modern roof paint (expensive, it was $160 a gallon when I used it) on a roll roof can drop interior house temperatures 5-10 degrees or more.

Does this increase the longevity of the roofing material if used on something like asphalt shingles?

It can, yes. But often with shingles you’re better of replacing them when worn with shingles that have the reflectivity “built in”.

We replaced our 40 year old tar and gravel roof (with small light colored stones) with a dark colored architectural shingle. There was an immediate, noticable difference. On summer nights you could feel the heat radiating out of the attic after a long day in sun.

This was in a cold climate, albeit at high latitude, so long days and low sun angle in the summer means more insolation. Since we rarely get above 70F here, I didn't think it would make much difference. Of course, it's only noticable a couple months out of the year.

In a cold climate it could help with heating costs though, I suppose?

It might help if we had some sunny fall days, until the snow flies, anyway.

how long does the paint last?

I believe it lasts quite a while on the sides and the top is rubbed to a reflective shine when trains run over it anyways.

Can't eroding paint chips pollute the environment ?

Same as when you fart

From the video: first trials achieved a cooling by 5 to 8°C.

Here's what SBB (the Swiss train operator) says at [0], german only:

SBB will not rely on tracks painted white because

- it makes it harder to discover cracks in the tracks

- with prolonged use the effect noticeably lessens to due accumulation of dirt

- ÖBB and SBB have measured he effect at ~5°C and that's not significant enough to be worth it.

[0] https://company.sbb.ch/de/medien/dossier-medienschaffende/so...

It might be a mixed bag and presumably different operators have different results. OeBB did not decide yet on the future, smaller operators are. Italy has been painting rails white for many years (40?) and continues to do so.

Why aren't they painting them backwards though?

Good point. However the paint in the hip is going to rub off anyway and what’s underneath is reflective.

And for a better effect they could use paint that can cool below the ambient temperature by radiating infrared to space (if they aren't already using that, but it's probably more expensive):

https://www.nature.com/articles/d41586-019-03911-8

Here is a YouTuber trying to making such paint:

https://www.youtube.com/watch?v=N3bJnKmeNJY

Another article:

https://greekreporter.com/2022/05/08/revolutionary-white-pai...

They started doing that a few years ago. Can see it in action on the main bridge going towards Glasgow Central as there's lots of points (15 platforms), seemed to help.

Alternately, I've seen videos in the likes of Chicago where they've literally installed pretty much bunsen burners and set the rails on fire to deal with the winter. https://www.youtube.com/watch?v=z76ywZDXyPw

Somewhere it was written that the ground underneath the trackbed also sinks in as it dries out. Is this not a mostly universal problem in addition to the temperature the tracks reach because of direct sunlight and lack of cool air?

Don’t the majority of trackbeds deform when the ground below them shrinks like a dry sponge? Exceptions may be a railroad bridge built on bedrock?

Missing context for international readers who perhaps may not be aware of the weather forecast for the UK next week:

“England braces for 40C temperatures as experts warn thousands could die“ - https://www.theguardian.com/uk-news/2022/jul/15/heat-emergen...

And for further context its the first RED (danger to life) warning [0] (for the purposes of heat, other red warning have been issued [1])

[0] https://www.metoffice.gov.uk/about-us/press-office/news/weat... [1] https://www.metoffice.gov.uk/weather/learn-about/past-uk-wea...

..since that warning was introduced in 2021

This will be the hottest temp ever recorded in the UK though.

The hottest temperature by a couple of degrees. That’s a ridiculously large jump.

To be fair they have been monitoring deaths before [0], just the first time there's a national warning to the public.

Quite a few schools have decided to use this warning to close as they are unable to manage heat on their premises [1]

[0] https://www.gov.uk/government/publications/phe-heatwave-mort...

It was introduced given the increase in temperature. This is the first time in recorded history that the temperature in the UK has been forecasted to reach 40°C

Most of the danger to life is people drowning in lakes, rivers etc.

British people are not normally found in lakes or rivers. If they are being driven into those dangerous environments by the weather, perhaps the weather could be considered dangerous.

According to the Romans it's common to find them there:

> Their form of rule is democratic for the most part, and they are very fond of plundering; consequently they choose their boldest men as rulers....They can endure hunger and cold and any kind of hardship; for they plunge into the swamps and exist there for many days with only their heads above water, and in the forests they support themselves upon bark and roots, and for all emergencies they prepare a certain kind of food, the eating of a small portion of which, the size of a bean, prevents them from feeling either hunger or thirst

https://penelope.uchicago.edu/~grout/encyclopaedia_romana/br...

It's historical writing so it must be true.

This is fantastic. I'm assuming that "a certain kind of food, the eating of a small portion of which, the size of a bean, prevents them from feeling either hunger or thirst" was Kendall Mint Cake.

> 40C

And for those of us in the US who don't know but aren't curious enough to look it up: 104 F

For people in the sf bay area, this is about as hot as it was in June (39C) when a Bart derailed due to heat-buckled tracks:

https://www.trains.com/trn/news-reviews/news-wire/heat-blame...

> The problem is that if we stressed Britain’s rails to the same degree as those in very hot countries, there would be the risk of increased tension on the rails in the winter.

This doesn't make sense, relative to many European countries the UK has much milder summers and winters.

The article explains that European countries replace their tracks between summer and winter

That seems inconsistent with my experience, unless they manage to do it completely without disturbing traffic.

A lot of the re-tensioning can be done overnight; there's no actual replacement, just changing the level of (pre)stress the steel is under.

All I could find is this paragraph:

> Some countries regularly have extremes in temperature that affect their railway. They may adjust their rails between summer and winter, or have other measures in place to manage the effects over the long term.

Which, when paraphrased, says: "Other countries may or may not do something else".

(Which, when paraphrased, says the PR person had no effing clue.)

Also "adjust" does not mean "replace".

In the UK, the railway in summer breaks because it gets too warm. In winter it breaks because leaves get on the line or it is too cold. If its snowing, forget it. For a country whose national pastime is the weather, we don't deal with it very well the second it shifts out of its bland average. We spend the whole year wishing it would get hot and sunny, and then freak out the second it does.

Sounds like Seattle!

you could argue that that's because we have such mild weather. in other countries typical changes in the weather are a bigger deal, so it's less appropriate for small talk. this would go some way to explaining why trains stop running when it's very rainy/hot/cold/leafy/snowy. we don't expect the weather to be drastic, and it rarely is, so we're not prepared for it when it happens.

I have no idea whether any of that is true (I doubt it), but it was interesting to write out.

British weather is indeed often milder than that of other countries, but it’s also often much less predictable. In some countries it’s pretty reliably hot and sunny all summer and snowy all winter.

In Britain, reliably, once per day it'll rain. Only the rest of the weather is unpredictable.

Not in the past few weeks!

this may go even further as to explaining it's popularity as a conversation topic

And for a country that invented the railway too! (Although also meaning we have the world's oldest system, and a very expansive system at that - even after the Beeching cuts)

> In winter it breaks because leaves get on the line

This is something that media talking heads harp on about, leaves don't break the line they cause wheels to slip. It's like criticising road traffic for not handling oil spills

Except leaves falling in Autumn is a known event that one would presume thinking human beings would factor in. If oil fell from the sky onto the road for several weeks each year, I think people would cry very loudly for a solution.

There's a pretty simple solution to this as well (which actually is used for the most part) - cut down the trees which are right next to the railway.

The Swiss railway has a (DE/FR/IT only) page at [0] to explain what they do.

- Start adjusting the tension on tracks starting in March when it gets warmer

- Use more expensive concrete sleepers where high forces appear (as TFA mentions)

- Cool exceptionally problematic parts of the track with water from tank cars

So in summary:

- spend money

That could explain why Network Rail isn't keen on doing any of that.

[0] https://company.sbb.ch/de/medien/dossier-medienschaffende/so...

It’s amazing how many problems are solvable simply by spending money.

A very Swiss attitude.

Like that time in 2016 when a Swiss town paid a 290k CHF fine rather than house Syrian refugees [0]!

[0] https://lenews.ch/2016/06/16/swiss-town-pays-instead-of-taki...

Yes that's shameful behavior. Good thing there are 5000 other communes that take their social responsibilities seriously.

Similarly in France there's a minimum percentage of social housing cities larger than X have to have, and some rich cities prefer paying the fine to actually building the required amounts of social housing.

It's amazing how many problems are solvable when a society chooses to solve them.

Note that the Swiss railway is charged fines for lateness to be paid to the state - so while I wouldn't say it's impossible that they just went and decided to take these measures to prevent rail buckling proactively, it's just as likely that they did the cost vs. payoff math.

So yes, society did solve this problem by electing officials who put those clauses into the railway's operating license - but there are a lot of steps in there that shouldn't be overlooked.

> - Start adjusting the tension on tracks starting in March when it gets warmer

And of course this also implies adjusting the tension on the tracks starting in October or so, too!

Despite saving all that money, the UK has the most expensive train ticket prices in Europe:

https://www.vouchercloud.com/resources/train-prices-across-e...

And most of that money (apart from the recently nationalised operators like Northern, ScotRail and LNER) goes back to the foreign-ran railways (Abellio/Netherlands, Amey/Keolis/France, Arriva/Germany).

It's ace!

And the least generous seat pitch and the slowest journey times on trunk routes.

Northern Japan has a much wider range of temperatures than the UK — -20C in winter to high 30s in summer would all be considered normal — and yet they can run high speed trains all year at 200+ km/h. How is that done?

They’ll perhaps use slab track, like HS2 in the UK will use.

This one? https://www.railengineer.co.uk/slab-track-paving-the-p-way/ How does this make the rails less likely to buckle? Just because it's held in place more tightly?

Yes. They actually talk about it in the article.

> The CWR is subject to compression loads due to temperature changes, which can cause buckling, or sharp lateral displacement. These phenomena are prevented using reinforced fastenings, sleepers and ballast.

https://www.ejrcf.or.jp/jrtr/jrtr15/f38_tec.html

I found the above, but it doesn't say that much about buckling. I don't think they use slab tracks however.

If buckling is the lateral movement of the track due to thermal expansion, I would imagine the old wooden sleepers would be much easier to pull sideways. Looking at the above link about slab tracks, they look far more secure and less likely to move sideways.

I wasn’t familiar with rail ballast but found this good link which explains what the term refers to and how it helps keep the rails aligned (explicitly the posted article talks about when current mitigation is indequate).

https://railroadrails.com/information/what-is-railway-ballas...

Shinkasen tracks have dense placement of strong fasteners and prestressed reinforced concrete slabs over thick cement asphalt mortar.

(basically tracks over concrete road over thick asphalt like road)

This is question of economics, not question of ability.

As with many (most?) high speed lines, it's done through maintenance overnight: the Shinkansen doesn't run from midnight till 6am, plus dealing with the potential expansion through additional work on the track during those overnight periods (largely by re-stressing the steel).

This is all about overnight access and about the cost of the work involved.

Is there a British train that runs overnight other than the Caledonian Sleeper? I don't think I ever saw a departure between 0:30h and 6:00h.

Freight.

See, e.g., https://www.realtimetrains.co.uk/search/detailed/gb-nr:SVG/2... for services booked to run through Stevenage during that time period next Monday.

Some extreme passenger services: 0132 London Kings Cross to Peterborough (0315), plus what is likely the return working 0324 Peterborough to London Kings Cross (0451).

But also as already mentioned, there's plenty of non-passenger services too.

Multiples of other solutions + expansion joints. Expanding long rails blend into fixed "tongue" rails and goes off track towards the sides.

1: (for illustrations) https://costep-webteam.hatenadiary.jp/entry/20061023/p1

2: (for illustrations) http://tarouroom.blog89.fc2.com/blog-entry-968.html

These joints are what I would have expected to be used more often.

Your 2 gives me advertising for some fat loss advert after having to give my adblocker a temporary exception. Why would that be on a blocklist at all? Is this a geo-thing?

Sorry for that. Those are free hosting predominantly for Japanese content, in turn attract little to no interest in Anglosphere. Perhaps that is why they were on a list? xrea.com is another such example.

No need to be. It was just strange and unexpected :-) So this is "homelandhosting", spamming the Gaijin from whereever with whatever by redirecting, to whatever the algorithm thinks appropriate ;->

I got redirected to some fake installer advertising despite having ABP enabled.

The British rail situation can lead to very interesting problems. https://www.londonreconnections.com/2015/know-run-story-behi... it's one of the most interesting postmortems of a non-software issue I've ever read.

The deeply inflexible union lead guidelines on worktime seem to be the main problem here. This is why most parts of the world can get things done when drivers aren’t healthy silly working time regulations to go a minute over their schedule

Not quite sure whether the limitation on the worktime of drivers is because of safety regulation or because union. It seemed like while certainly the trigger was the worktime the real problem here were the way too many parties and layers involved and the coordination issues arising from those.

I don't see how this really explains anything. I have never understood how continuously-welded rails work compared with the old-style track using short rails and fishplates joining them, and this link doesnt help (for me at least).

Considering this is Network Rail, I agree, the opportunity to answer a lot of obvious questions has been seriously overlooked.

I found this article and associated video, along with the Wikipedia article to be useful for filling in the gaps from the article:

https://broadwayextensionblog.blogspot.com/2017/03/stressing...

https://www.youtube.com/watch?v=I8EZ6pEAyLc

https://en.wikipedia.org/wiki/Rail_stressing

http://vinchad.blogspot.com/2014/06/ever-wondered-why-contin...

> Its laid it's in tension by hydraulically stretching it before cutting to length and welding to the previous length. Sufficient tension is applied to achieve a 'Stress Free Temperature' (SFT) of 27 degrees C (i.e to relieve the tension by expansion the rail would need to be heated by the sun to 27C, whereupon it would neither be in tension or compression).

Apparently they lay it "hot" and so normally when it is cooler than that it is actually "pulling" on itself trying to shrink, and when it gets hotter than that it begins to compress.

If it can't compress it buckles, if it can't shrink then the tension grows, but steel has incredible tensile strength.

I wonder if you can combine rail sections with different zero-stress temperatures to cancel out across a wider range?

The tension is between each pair of sleepers (60 cm distance), how would that work?

Aha, I thought it was over longer segments of track.

Here’s a link showing the tensioning process using a petrol powered hydraulic cylinder: https://broadwayextensionblog.blogspot.com/2017/03/stressing...

It mentions the pre-stressing, but a better explanation is at https://worldwiderails.com/how-do-railroads-deal-with-therma...

It also explains some of the maintenance procedures.

This article shows mechanical tensioning using a hydraulic cylinder: https://broadwayextensionblog.blogspot.com/2017/03/stressing... although it is clearly a straight section. Do curved sections of rail just expand and contract?

The parent link says “Railroads deal with thermal expansion by heating the rail prior to installation”.

reddit/etmidust wrote “I was a manager of track maintenance for a US railroad for a while. When they lay new rail, part of the process is a ‘heater car’[1]. This machine rides the rail and is basically a multi headed blow torch to heat the new rail to the ‘rail neutral temperature’(SFT). At this point the rail is not yet spiked down to the ties so that it has a chance to grow and expand. After the heater car some other rail cars called spikers follow to spike the new rail down. That is how they ‘pre-stress’ the rail. I am skipping some steps, but that is the gist of it.”

[1] https://imgur.io/tvCy9C2

https://en.m.wikipedia.org/wiki/Rail_stressing

Pasting a couple of @GarethDennis tweets which answer this:

It is worth pointing out that jointed rather than welded track WILL NOT solve the buckling problem.

In fact, jointed track is at a MUCH HIGHER risk of buckling in heat than welded rails as gaps close and there are 160+ joints PER MILE to maintain...

...plus jointed track is generally lighter, weaker and thus at higher risk of buckling (most GB buckles are in jointed, not welded track).

Bolted joints also have a nasty habit of disintegrating under traffic and derailing trains (hence use of welded track to start with)

Your arguments make sense, so it appears that continuously-welded rails should be better than the traditional jointed rails.

Nevertheless, when I was young I traveled frequently by train. During some decades, I have never seen problems caused to the train traffic by too high temperatures, on traditional jointed rails.

On the other hand, in the last few years, whenever I happened to travel by train through Germany on continuously-welded rails and the weather was hot, there were train delays due to the rails.

So it seems that there is some disconnection between theory and practice. Maybe the new continuously-welded rails have been designed based on ancient recorded temperature ranges that are no longer valid due to climate changes, as already suggested in the parent article, but in any case something is wrong with the design of modern rails.

In the parent article it is mentioned that changing the stress-free temperature to a higher value is not good enough, because the strength of the rails could be exceeded during cold winters. So it is likely that the rails would have to also be thicker, increasing their cost.

I don't know anything about German weather, but according to a random article on Wikipedia: https://en.m.wikipedia.org/wiki/List_of_extreme_temperatures... says 9 of 16 extreme maximums are within the last year (with one about a month over).

> In fact, jointed track is at a MUCH HIGHER risk of buckling in heat than welded rails as gaps close and there are 160+ joints PER MILE to maintain...

Why? Don't the gaps give the track some amount of play which would lower the pressure and therefore the risk of buckling?

I don't have a reliable source, but I recall hearing that expansion gaps require the rails to have some freedom to slide back-and-forth, as the expansion and contraction occurs over the whole length. The rails are not guaranteed to go back to where they started when they cool down, so gaps can close up (while correspondingly widening elsewhere to compensate), and if you have too many closed gaps in a row, the rails can jam.

The center of each section of rail could be bolted to the ties with non-sliding holes.

I believe you were misinformed.

The rails have not a real freedom to slide, they have two different forms of resistance, the one provided by the ties and the one provided by the junction, there is only a given temperature range where they can slide.

The rail goes into a cycle, you need some 3-4 C° to win the resistance of the joint (in this part the rail is compressed by some 6000 kg of resistance) and some 6-7 degrees more to win the resistance of the ties (some 10-12000 kg more of compression), then it becomes "free sliding" until the gap in the joint closes, this needs 12-13 C° more and the rail is again compressed by the ends.

When the temperatures lowers, the same cycle is reversed, the rail first contracts until the gap starts to appear and widens, then you have again a range where it is free sliding, then the two resistances come into play again, when the temperature lowers further the excursion is limited by the joints (usually they allow 14 mm travel) and the rail is subject to traction (as opposed to compression).

The only point that never moves is the tie at the center of the rail length, you have to imagine a spring that you try to expand by pulling the two sides, it will return to its original shape, all forces are relative to the center, so there is not any reason why the rail should not come back to its original position.

Check this:

https://pwayblog.com/2017/03/06/jointed-track-response-to-ra...

In practice - strangely enough - rails behave very similar to the theory.

The gaps do give some amount of play. The trouble is that once the temperature exceeds the design maximum the gaps close up completely and all that expansion force is directed into hard metal-on-metal contact, at which point something has to give. Jointed rail tracks are not designed to handle those forces without buckling because the whole point of having the joints is so that they don't have to.

How do engineers plan for thermal expansion when laying traintracks in deserts where the daytime and nighttime temperatures are vastly different? - https://old.reddit.com/r/askscience/comments/8yxd21/how_do_e...

It seems that the answer to your question is that the continuously-welded rails work only within a relatively narrow temperature range.

As mentioned at this link, the continuously-welded rails are made to be stress free at a specified temperature, for example 27 degrees Celsius in UK.

At lower temperatures the rails contract, which does not have bad consequences unless the temperature becomes so low that the rails will crack, because their strength has been exceeded by the contraction stress. At very low temperatures the trains may need to reduce their speed, so that the rails will not crack due to the additional stresses caused by a passing train.

At higher temperatures, the rails dilate, and when the temperature is high enough they will buckle. Due to that, the trains may need to reduce the speed, or even stop and wait for the rails to become colder.

At least a part of the rails from Germany have also been updated with continuously-welded rails.

In one of my trips, it was a hot summer day and because of the rail buckling all the trains had huge delays. Even if I should have arrived at the Frankfurt airport about 3 hours before my flight, due to the train delays caused by the hot weather, I have arrived so late that I have lost the flight.

Steel is a bit like rubber if your holding it with enough force…

Article doesn't mention but welded track does have expansion joints. They just exceed their expansion range at some point. Also rails can expand beyond their mounting geometry between the joints, on curves.

I noticed the white sprayed tracks in Italy recently. It didn't prevent the network becoming congested due to speed restrictions imposed as temperatures exceeded 105F.

1.1 degree above pre-industrial reference and it is already a nightmare and yet we drill again to keep the carbon economy running.

not a climatologist (just an interested physicist) but (some of) these heatwaves overshoot models predictions by a fair margin.

can't wait for the fresh papers quantifying that this autumn. it's gonna be bleak.

I'm starting to take a small crumb of comfort that my advancing years mean I'm probably going to be gone before it starts getting really bleak. Feel bad for all my younger relatives though.

Climate models don't predict individual heat waves, and as we are told every time there's a cold snap, climate isn't weather so cold periods aren't evidence that the globe isn't warming. That cuts in both directions, doesn't it.

This is a very common engineering challenge, but I don't have experience with the specifics of rails.

Roads (especially near bridges) have expansion joints so that the sections can expand and contract in hotter/colder weather. It looks like slab tracks just have more support and try to fight expansion. This will increase the load required to buckle the tracks, but it will put the entire system (slabs, rails) under more stress.

In other industries this can really affect the entire design of mechanisms. Motor mounts in cars look to allow thermal expansion between the hot engine components and the chassis without letting the whole thing shake apart by being too loose. You can make designs such that they are very close to being statically determinate, meaning there is only one restraint for each of the 6 degrees of freedom, so relative thermal expansion doesn't stress and fatigue adjacent structures. However, that means that adding redundancy in case a single support failure can be quite tricky...

One area where thermal expansion is very challenging is fasteners. I've seen some machines where the joint had to be different materials than the fasteners, and it had to survive a wide temperature range, so the torque on the fastener, including testing it and calibrating the tools, became extremely critical.

as someone who 30 years ago laid rail for the RJ corman railroad, the hardest sites were in the southwest. track that can go from near zero to fifty celcius is not long for this world. if the job site was quiet some days you could even hear the ties groaning as the sun came up.

in the US we use a vision system on a special rail repair engine that checks for issues, but common controls are lowering speed and some days just not using certain tracks

Computer vision can be used to classify sun kinks at speed from a train-mounted sensor.

The GPS-triangulated sun kink data can then be used to dispatch repair teams to the appropriate location preventing derailments in the process.

This has been studied academically and commercially in the US for a few years, at least. I'm not aware of a commercial deployment, but it may be in progress given the published R&D.

For instance:

https://arxiv.org/pdf/1802.01286.pdf

From the paper: "Sun kink classifier could classify professionally simulated sun kink videos with a precision of 97.5%."

The challenge is ensuring you have sufficiently frequent passes on hot days, and therefore sufficient fitted trains, right?

That paper seems to be notable because it’s doing it from vision alone (and no LIDAR), whereas similar things (including gauging generally) have been used commercially for a while; see eg http://www.rail-vision.co.uk/

Not sure if this is relevant here, but shiny metal surfaces emit less thermal energy than painted metal surfaces. Learned about this recently while reading about home heating radiators.

https://en.wikipedia.org/wiki/Thermal_radiation#Surface_effe...

Rusty metal covered in dirt, grease, and oil probably does pretty badly though.

> More than three-quarters of track on the network today is modern on concrete sleepers.

"modern"? or "mounted"?

Both, I think their point is that they’ve got rid of most of the wooden sleepers and replaced them with ‘modern’ concrete.

Unfortunately, ‘modern’ is a pretty meaningless word and tells us nothing as to the why of this.

Looks to me that they forgot a comma. It probably should be "modern, on concrete sleepers."

Yes, with a comma it would work better.

In Holland they used to leave big gaps, diagonally cut so there'd be overlap.

This have the trains a rythmic kadunk sound that's even been popularized in songs :) It also worked quite well as far as I know but I suppose it caused more wear and tear on the rolling stock.

Not sure if this is still done there though.

That sound does not seem to be there anymore, but that could just be because of better isolation or suspension on the trains.

> Not sure if this is still done there though.

It's not[1], and there is risk of track buckles in the Netherlands as well. ProRail does extra monitoring during heatwaves[2]. I don't remember ever hearing news about this being a notable problem, but it probably does happen.

[1]: https://www.prorail.nl/veelgestelde-vragen/hoe-vangt-prorail... [2]: https://www.prorail.nl/nieuws/maatregelen-tegen-de-hitte

I wonder if this new 'voegloos' stuff is quite as good at absorbing heat as the 'kedeng kedeng' ones though :)

I don't remember that in the 80s/90s there were such concerns and I had family working on railway maintenance. The climate problem wasn't as big back then but we had some scorching summers too.

Instead the autumn was the all hands on deck period with leaves on the tracks and later in the autumn snow freezing the switches.

I wonder if it's the same buckling we mean when we're studying structural engineering:

https://en.wikipedia.org/wiki/Buckling

The interesting thing here is that when something buckles, it's not the material failing like when you crush a cake. It can buckle well before you reach the force needed to break the steel under compression.

Definitely the same kind of buckling. Here's an example from a couple of years ago in the news https://www.bbc.co.uk/news/uk-england-cumbria-44658254

Check Google images for some more extreme examples.

Interesting - that looks like wooden sleepers too.

There is a similar effect for bitumen roads - cities choose a grade of bitumen for the range of temps that they are going experience - you're stuck between it all getting too sticky and cracking in the cold - too big a range and they make concrete roads.

Global warming leaves some cities (like mine) with an enormous inventory of roads that are failing when temps reach the (new) top end

Ha! The other day, I was having a short chat with a fellow commuter on this very topic (including 'why not in other countries?'), in the context of the expected heat wave on Monday and Tuesday. And the reason, I speculated, was exactly same as mentioned in the article. I'm glad I wasn't wrong. I'll share this article if I see them again.

Does UK really have such large temperature variability?

I thought inland European countries have it way worse.

Yes, you are correct. The UK has a temperate climate, unlike the continental climate in many other European countries.

It still occurs in other countries too, you're just reading the explanation by Network Rail who manage UK tracks.

Yes, the UK is relatively mild. That's why they've gotten away with less proactive measures and monitoring of tracks. With the weather getting more extreme, railways need to spend more to handle it. That's tough to accomplish when these for-profit companies try to eke out bigger profit margins each year.

I love how this article answers the question in the first couple sentences.

Video of some rails buckling https://www.youtube.com/watch?v=jJeiYaSFCf0

Quicker than I imagined

Couldn’t they just have a bit of “wiggle-room” in the clamp to allow for slight deformation? How tight is the tolerance on gauge?

Sounds like someone needs to invent some sort of expansion joint. I assume its a hard engineering problem with significant trade offs.

There is probably one, but the design was done for temperature range outside the current conditions. You can accommodate only for so much and at some point it make sense to say yeah, this temperature is good enough. There is very likely some trade-offs involved as well.

> Sounds like someone needs to invent some sort of expansion joint.

As the article says, there basically isn't the money or will to fix the problem, so they're leaving it as is.

Such things exist (https://en.wikipedia.org/wiki/Breather_switch), but so far they've been mostly only used for localised expansion/contraction/movement hotspots, i.e. bridges longer that 50 – 100 m or so.

Why don’t high speed rails buckle in southern Europe or Asia?

Tl;dr

They don’t stress them to higher temps because (they say) it will cause fractures/stress at winter temps

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