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Why rails buckle in Britain
- colordrops 4y agoI love how this article answers the question in the first couple sentences.
- the_mitsuhiko 4y agoWhat 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 https://youtu.be/GBMWHAkk6xM?t=52
- nomdep 4y agoSo einfach, so wirksam
- O__________O 4y agoUnable 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 https://news.ycombinator.com/item?id=27571809
- zabzonk 4y agoI 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!
- Akronymus 4y ago"So easy, so effective" seems like the most appropriate translation in this case
- pvg 4y agoSubmissions 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.
- LargoLasskhyfv 4y agoKannitverstaan! Was Du saggn?
- dang 4y agoSubmissions 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.
- O__________O 4y agoUnderstand and agree, thanks for taking the time to respond!
- linker3000 4y agoFrom 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."
- the_mitsuhiko 4y agoLooks surprisingly laborious if this Twitter video is to trust: https://twitter.com/networkrail/status/1547986150723244032 https://twitter.com/networkrail/status/1547986150723244032
- pimlottc 4y agoYou’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.
- fl0id 4y agoHow would this be any better then the video? It would also be much more expensive and complex then what they made.
- peterbraden 4y agoor just paint behind the robot
- rayiner 4y agoAnd use a pencil instead of inventing a pen that works in zero gravity.
- happymellon 4y agoThe 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.
- bombcar 4y agoThe 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.
- toomuchtodo 4y agoDoes this increase the longevity of the roofing material if used on something like asphalt shingles?
- bombcar 4y agoIt can, yes. But often with shingles you’re better of replacing them when worn with shingles that have the reflectivity “built in”.
- mordechai9000 4y agoWe 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.
- nine_k 4y agoIn a cold climate it could help with heating costs though, I suppose?
- mordechai9000 4y agoIt might help if we had some sunny fall days, until the snow flies, anyway.
- ekianjo 4y agohow long does the paint last?
- sschueller 4y agoI believe it lasts quite a while on the sides and the top is rubbed to a reflective shine when trains run over it anyways.
- cassepipe 4y agoCan't eroding paint chips pollute the environment ?
- Faaak 4y agoSame as when you fart
- masswerk 4y agoFrom the video: first trials achieved a cooling by 5 to 8°C.
- ThePadawan 4y agoHere'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/sommerdienst-sbb.html https://company.sbb.ch/de/medien/dossier-medienschaffende/so...
- the_mitsuhiko 4y agoIt 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.
- curiousgal 4y agoWhy aren't they painting them backwards though?
- lostlogin 4y agoGood point. However the paint in the hip is going to rub off anyway and what’s underneath is reflective.
- spyder 4y agoAnd 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 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 https://www.youtube.com/watch?v=N3bJnKmeNJY Another article: https://greekreporter.com/2022/05/08/revolutionary-white-paint-cool-greek-island-buildings-better-than-ac/ https://greekreporter.com/2022/05/08/revolutionary-white-pai...
- benbristow 4y agoThey 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 https://www.youtube.com/watch?v=z76ywZDXyPw
- nier 4y agoSomewhere 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?
- zabzonk 4y agoI 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).
- dazc 4y agoConsidering this is Network Rail, I agree, the opportunity to answer a lot of obvious questions has been seriously overlooked.
- scrlk 4y agoI 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-at-laverton.html https://broadwayextensionblog.blogspot.com/2017/03/stressing... https://www.youtube.com/watch?v=I8EZ6pEAyLc https://www.youtube.com/watch?v=I8EZ6pEAyLc https://en.wikipedia.org/wiki/Rail_stressing https://en.wikipedia.org/wiki/Rail_stressing
- bombcar 4y agohttp://vinchad.blogspot.com/2014/06/ever-wondered-why-continuously-welded.html 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.
- ssl232 4y agoI wonder if you can combine rail sections with different zero-stress temperatures to cancel out across a wider range?
- rwmj 4y agoNorthern 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?
- smcl 4y agoThey’ll perhaps use slab track, like HS2 in the UK will use.
- rwmj 4y agoThis one? https://www.railengineer.co.uk/slab-track-paving-the-p-way/ 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?
- pkulak 4y agoYes. They actually talk about it in the article.
- bitdivision 4y ago> 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 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.
- gumby 4y agoI 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-ballast/ https://railroadrails.com/information/what-is-railway-ballas...
- bambax 4y ago> More than three-quarters of track on the network today is modern on concrete sleepers. "modern"? or "mounted"?
- mnd999 4y agoBoth, 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.
- mrob 4y agoLooks to me that they forgot a comma. It probably should be "modern, on concrete sleepers."
- bambax 4y agoYes, with a comma it would work better.
- N_A_T_E 4y agoSounds like someone needs to invent some sort of expansion joint. I assume its a hard engineering problem with significant trade offs.
- Ekaros 4y agoThere 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.
- chrisseaton 4y ago> 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.
- iggldiggl 4y agoSuch things exist (https://en.wikipedia.org/wiki/Breather_switch 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.
- mechhacker 4y agoThis 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.
- dboreham 4y agoArticle 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.
- immmmmm 4y ago1.1 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.
- zimpenfish 4y agoI'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.
- origin_path 4y agoClimate 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.
- Linda703 4y ago[dead]
- lordnacho 4y agoI wonder if it's the same buckling we mean when we're studying structural engineering: https://en.wikipedia.org/wiki/Buckling 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.
- philo23 4y agoDefinitely 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 https://www.bbc.co.uk/news/uk-england-cumbria-44658254 Check Google images for some more extreme examples.
- lostlogin 4y agoInteresting - that looks like wooden sleepers too.
- WithinReason 4y ago> 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.
- acer4666 4y agoThe article explains that European countries replace their tracks between summer and winter
- deleted 4y ago[deleted]
- lrem 4y agoThat seems inconsistent with my experience, unless they manage to do it completely without disturbing traffic.
- gsnedders 4y agoA 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.
- ThePadawan 4y agoAll 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.)
- jaclaz 4y agoAlso "adjust" does not mean "replace".
- GekkePrutser 4y agoIn 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.
- t0mas88 4y agoThat sound does not seem to be there anymore, but that could just be because of better isolation or suspension on the trains.
- jorams 4y ago> 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-de-uitzetting-van-de-spoorrails-door-warmte-op https://www.prorail.nl/veelgestelde-vragen/hoe-vangt-prorail... [2]: https://www.prorail.nl/nieuws/maatregelen-tegen-de-hitte https://www.prorail.nl/nieuws/maatregelen-tegen-de-hitte
- GekkePrutser 4y agoI 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.
- jameshart 4y agoMissing 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-emergency-declared-in-england-as-temperature-expected-to-hit-40c https://www.theguardian.com/uk-news/2022/jul/15/heat-emergen...
- dcomp 4y agoAnd 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/weather-and-climate/2022/red-extreme-heat-warning https://www.metoffice.gov.uk/about-us/press-office/news/weat... [1] https://www.metoffice.gov.uk/weather/learn-about/past-uk-weather-events https://www.metoffice.gov.uk/weather/learn-about/past-uk-wea...
- rozab 4y ago..since that warning was introduced in 2021
- tfsh 4y agoIt 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
- mnobu 4y agoThis will be the hottest temp ever recorded in the UK though.
- randomsearch 4y agoThe hottest temperature by a couple of degrees. That’s a ridiculously large jump.
- dcomp 4y ago
- scotty79 4y agoDoes UK really have such large temperature variability? I thought inland European countries have it way worse.
- smcl 4y agoIt still occurs in other countries too, you're just reading the explanation by Network Rail who manage UK tracks.
- 317070 4y agoYes, you are correct. The UK has a temperate climate, unlike the continental climate in many other European countries.
- Arn_Thor 4y agoYes, 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.
- MilaM 4y agoNot 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_effects https://en.wikipedia.org/wiki/Thermal_radiation#Surface_effe...
- lazide 4y agoRusty metal covered in dirt, grease, and oil probably does pretty badly though.
- penguin_booze 4y agoHa! 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.
- jpollock 4y agoThis 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_welded_rail https://en.wikipedia.org/wiki/Railway_track#Continuous_welde... [2] https://en.wikipedia.org/wiki/Rail_stressing https://en.wikipedia.org/wiki/Rail_stressing [3] Thermite track welding: https://www.youtube.com/watch?v=5uxsFglz2ig https://www.youtube.com/watch?v=5uxsFglz2ig [4] https://www.nzherald.co.nz/nz/peter-calder-old-methods-keep-rails-like-new/KSMG4EQQ373I45O3JISP52LEYY/ https://www.nzherald.co.nz/nz/peter-calder-old-methods-keep-...
- bobthepanda 4y agoCWR 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.
- int_19h 4y agoIt 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).
- bombcar 4y agoMuch 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.
- edf13 4y agoTl;dr They don’t stress them to higher temps because (they say) it will cause fractures/stress at winter temps
- davidthewatson 4y agoComputer 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 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%."
- gsnedders 4y agoThe 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/ http://www.rail-vision.co.uk/
- nimbius 4y agoas 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
- chx 4y agoThe British rail situation can lead to very interesting problems. https://www.londonreconnections.com/2015/know-run-story-behind-xmas-kings-cross-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.
- robk 4y agoThe 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
- chx 4y agoNot 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.
- Taniwha 4y agoThere 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
- napier 4y agoWhy don’t high speed rails buckle in southern Europe or Asia?
- supermatt 4y agoCouldn’t they just have a bit of “wiggle-room” in the clamp to allow for slight deformation? How tight is the tolerance on gauge?
- tim333 4y agoVideo of some rails buckling https://www.youtube.com/watch?v=jJeiYaSFCf0 https://www.youtube.com/watch?v=jJeiYaSFCf0 Quicker than I imagined