25 ms·

Is TfL losing the battle against heat on the Victoria line?

125 points by zeristor 1y ago

Y_Y 1y ago
> Historically, the Underground infrastructure offered a respite from warm weather, indicated in Austin Cooper’s ‘It is cooler below’ poster, issued in 1924 by the Underground group to promote a more comfortable experience of travel during warm weather. A century of burrowing commuter-worms unfortunately managed to bake all the beautiful wet clay that kept the tunnels tolerable when the sun was shining about. It seems straightforward to me that it would be enough to rehydrate the ground. Just need (approximately), 400km of track * 25m average depth * 3m tunnel width * 20% moisture content of wet clay = 6 billion litres of water Sounds like a lot but it's only about 1/300th of the yearly flow of the Thames.
- lloydatkinson 1y ago
  Have you thought of suggesting this to TfL? There has to be something here.
  - thyristan 1y ago
    Unfortunately, hydrating clay is extremely hard to do. Clay is what you use as a water-tight material in dams, artificial lakes, waste dumps and stuff like that, because water doesn't really pass through it.
  - rjh29 1y ago
    Yes, people whose day job is to explore all possible options have surely missed this extremely obvious idea.
    - lloydatkinson 1y ago
      Alright smart arse.
    - mike_hearn 1y ago
      In fairness, TfL ran a public competition to source cooling ideas some years ago, so the people whose day job is to explore all the possibilities clearly felt like they were out of ideas.
  - Y_Y 1y ago
    It was just a bit of a shower thought to be honest, but it looks like there are cleverer and more responsible people who've considered similar schemes. As I posted in a cousin comment, I found this nice blog post examining some of the more serious ideas, including water-cooling: https://www.ianvisits.co.uk/articles/cooling-the-london-underground-220/ https://www.ianvisits.co.uk/articles/cooling-the-london-unde...
- heisenzombie 1y ago
  <man walks into sauna room> Ooh, it's a bit hot in here! I better throw some water on these rocks to cool them down. Joking aside, I actually don't know how dry it is in the underground, and therefore whether adding water for evaporative cooling would work. I would have assumed it was quite humid, but maybe not?
  - Cthulhu_ 1y ago
    It would be if they tried cooling it with water, for sure; evaporative cooling would only work if there's enough airflow, else they'd just get 100% humidity so it would be both hot and humid.
- ajb 1y ago
  It seems implausible to me that the clay is dehydrated. The Victoria line was only built in the 60s and has a waterproof lining. (It's also built with asbestos cement, unfortunately, which is no doubt a problem when they need to cut it for whatever reason)
  - Y_Y 1y ago
    The cement can negatively effect the water retenction of the clay, as does of course the temperature. The water needn't seep into the tunnel, just be moved away from it to adjacted areas. There's a nice article here which goes into more detail: https://www.ianvisits.co.uk/articles/cooling-the-london-underground-220/ https://www.ianvisits.co.uk/articles/cooling-the-london-unde...
- avianlyric 1y ago
  I don’t think the hydration of the clay is the important element here. Rather I suspect it’s simple just the sheer mass of clay, wet or otherwise, that’s involved. There’s a reason why ground source heat pumps work so well. It’s because the ground is such a fantastically huge heat sink/source that in most scenarios we consider it capable of sinking or sourcing a practically unlimited amount of heat. Unfortunately one of the scenarios where this breaks down, is when you stick a bunch of tunnels in the ground, then pump a crap ton of energy into those tunnels years round, and expect the ground to sink all the heat away. Turns out, if you do that, the ground itself starts heating up, and given that clay is a reasonable good insulator, it’s like wrapping all those tunnels in wool jumpers. I would point out as well that all these tunnels are “deep level” tunnels running at an average depth of 24 meters and getting as low as 67 meters. The heat of the sun on the ground surface will have approximately zero impact on the tunnel temperatures. 24 meters of clay is a lot of insulation to work with.
  - jjcob 1y ago
    I think you are right. The graph at the bottom of the article shows that temperatures dropped around 2020 (presumably less traffic due to the pandemic). So the ground can take up more heat, but it can't do it quickly enough.
  - Y_Y 1y ago
    My original comment was meant to be tounge-in-cheek, but I would like to add the advantage of wet clay is really in its thermal conductivity[0] which is roughly two to four times higher than dry clay. It will also have higher thermal capacity, so that high frequency fluctuations (like day/night) will be smoothed out. [0] https://www.mdpi.com/2571-8789/8/2/47 https://www.mdpi.com/2571-8789/8/2/47 (I don't think my comment implied that the sunshine makes it hot in the tunnel, only that when it's hot above ground it's nice to be cool below, like in the poster. And I did include a figure of 25m for average depth, I've spent enough time on their endless stairs to know that the TfL delved to greedily and too deep. This spiral staircase has 320 steps, I shudder.)
- zeristor 1y ago
  At a couple of stations a river passes by and that is used to cool the station. I think Oxford Circus is one.
- Theodores 1y ago
  > Austin Cooper’s ‘It is cooler below’ poster As I see it, it is just a marketing problem with easy solutions. There is psychology and reverse psychology. You could fool people into embracing the heat by redecorating the stations and trains to make it a 'journey to hell, via the centre of the earth'. The stops south of the river could be marketed as Dante's inferno and hellish. Or you could go the other way, to make it kitch Hawaiian themed, so people expect the heat and to embrace it as a mini-holiday. Or, the stations could be redecorated as if it were a trip to the Antarctic, so people see images of penguins braving the ice, with murals from the Shackleton days, to imagine they are cold. In places like Moscow the underground train stations give the impression that people are in splendid palaces, this works pretty well. As I see it, TfL just need to up their decor game, problem solved.
  - Affric 1y ago
    I hate that I think Theres a lot to this
azernik 1y ago
"The average temperatures on the Victoria line have risen by almost seven degrees since 2013 – nearly a *30%* increase. Conversely, the increase in the average annual temperatures across all Underground lines from 2013 to 2024 was merely *seven percent*, placing Victoria’s temperature rise vastly above that." Using percentages to talk about changes in non-Kelvin temperatures is crazy.
- OJFord 1y ago
  It would definitely be crazy in Fahrenheit, but in centigrade I think it makes some sort of intuitive (if not scientific) sense. (Together with the sea-level assumption we always make in casual temperature discussion anyway.)
  - azernik 1y ago
    It makes just as much intuitive sense in Fahrenheit as it does in centigrade.
    - perching_aix 1y ago
      Why? The slope of the Fahrenheit scale is different to the Celsius and Kelvin scales, but the slope of the latter two does match.
      - meindnoch 1y ago
        Ok. Then please explain what % does the temperature rise when going from 0 Celsius to 5 Celsius!
        stephencanon 1y ago
        Or -1 to 1 Celsius, for that matter.
        chihuahua 1y ago
chiph 1y ago
Looking at the temperature chart and the significant drop in 2020 during the pandemic, the source is certainly the trains and people themselves. (fewer trains moving, less heat added back then). At this point I expect the infrastructure is heat soaked and will need a prolonged period of cooling to bring temps down. i.e. don't expect instant results. Moving more air through the tunnels, adding A/C systems - both have a problem of needing room up on the surface for blowers and compressors, something that is hard to do in modern London. Tough problem.
- meindnoch 1y ago
  This. Brake friction pumps heat into the ground at a higher rate than it could dissipate away.
  - eternauta3k 1y ago
    Aren't they using regenerative braking?
    - Zigurd 1y ago
      Some parts of the London underground use passive energy recovery by locating stations nearer to the surface than most of the tunnel between them. Trains start by rolling downhill and when they approach a station, uphill.
    - blipvert 1y ago
      Yes. https://tfl.gov.uk/corporate/transparency/freedom-of-information/foi-request-detail?referenceId=FOI-3010-2223 https://tfl.gov.uk/corporate/transparency/freedom-of-informa...
      - altairprime 1y ago
        > If the line is unreceptive, braking energy is dissipated in on-board resistors How many watts are dumped into onboard heat-generating resistors on the trains in the most heat-affected lines per week? Should regenerative braking be disabled in aboveground trains when heat impacts reach uncomfortable levels in belowground tunnels? > Regenerated braking energy is transmitted to the London Underground high voltage distribution network If regenerative braking oversupply is inducing higher temperatures belowground through on-train resistors, then only an operational change to aboveground mode would be required to minimize that induced heating during times of thermal need. (Obviously longer-term solutions with non-zero capital expenditure exist that could be pursued in parallel.)
randallsquared 1y ago
> Temperatures hiked as high as 31.1[C] degrees in August 2024 [...] So, I can imagine that this is a long-term problem, but it seems odd that the panic is setting in already, when some platforms in the NYC subway regularly exceed 40C / 104F every summer? This article seems in a similar genre to the breathless advice to remain inside in Britain when the outside temperature might get above 27C / 81F, otherwise known as a not-particularly-warm spring day in much of the US in most years.
- masklinn 1y ago
  > This article seems in a similar genre to the breathless advice to remain inside in Britain when the outside temperature might get above 27C / 81F, otherwise known as a not-particularly-warm spring day in much of the US in most years. It’s really not breathless, because high temperatures and how to handle them is completely absent from the cultural baggage. I don’t live in the UK, but in a place which similarly does not have much in the way of high temperatures historically and low AC penetration, and during heat spikes I see a significant fraction of my neighbours with windows wide open at 4PM. Habituation is also a significant factor. The UK does not get a smooth transition into higher normals, it gets heatwaves.
  - tim333 1y ago
    I live in the UK and a lot is down to the tabloid newspapers trying to get some sales with 'Horror Heatwave!' type headlines when it's 27C. Brits go on holiday to Spain, we are familiar with heat.
    - tialaramex 1y ago
      Statistically we know that humans who live somewhere that you'll just die in the regular environment due to climate behave very differently from humans who live in a temperate climate like the UK when the actual temperature warrants the same behaviour. If you live in Nunavut or the Iran / Pakistan border you already knew that you can just die from temperature extremes and so you need to ensure you stay at a survivable temperature, in Wales it's quite unexpected. As a result you actually get many more deaths from extremes in countries where the usual climate is temperate like Britain, even when the actual temperatures aren't as extreme as in countries where that would be more common.
cherryteastain 1y ago
> tunnel ventilation installations, chiller systems pumping chilled air into mid-tunnel shafts and regenerative braking to reduce heat generated by trains breaking The hoops TfL jumps through just to not extend AC to the rolling stock in more lines are baffling. At least we finally got some AC in the new Piccadilly rolling stock.
- deleted 1y ago
  [deleted]
- pitaj 1y ago
  AC will only make the problem worse in the long term. Picadilly got AC because it has above-ground sections.
  - cherryteastain 1y ago
    You can redesign the signalling systems etc to work at even 40C, plenty of countries do it. You can't redesign humans to feel comfortable inside a stuffy carriage at 35C.
    - crote 1y ago
      Sure, but that means the stations will also have 40C air. Can the humans handle that? And it's going to be 42C the next year, 44C the year after, and so on...
      - FredFS456 1y ago
        Platform screen doors can isolate tunnel temperatures from platform temperatures.
        andylynch 1y ago
        That doesn't help the people maintaining the tunnels and everything inside them.
    - 1y ago
Aachen 1y ago
Isn't heat free energy in a place like London? I know very little about metro systems so please correct me if this is insane: wouldn't the people living above the tubes be happy to get a heat exchanger (passive) or heat pump (active, but takes more of the heat) that prewarms their hot water supply? People still take warm showers and boil tea and rice/pasta in summer, and in winter the purpose should be obvious. If the water comes in at 30 instead of 10 degrees C, you need to add only a few degrees for showers and floor heating
- joshlk 1y ago
  What do you do in the summer when the homes don’t want the heat?
  - jairuhme 1y ago
    People still take hot showers and use hot water
  - crote 1y ago
    That doesn't have to be a problem in practice. The entire issue is that the earth surrounding the tubes is acting as a giant buffer. Enough heat has been dumped into it over the years that it has permanently warmed up. Draw heat from it during the winter to warm up homes, and it'll be able to absorb more heat from the tunnel air during the summer.
    - TheOtherHobbes 1y ago
      And because it's permanently warmed up, the long term consequence is the line becomes a health hazard and has to be closed for increasingly long periods. When wet bulb > body temp people start getting heat stroke, which leads to fainting and potentially death - a bad look for a public transport system. The likely remedy is to install gigantic refrigeration units in the ventilation shafts and pump in cold air. This will be hugely expensive to build and run. But the alternative is a tube line that can't be used. So there may not be much choice.
  - 1y ago
brightbeige 1y ago
In case you also couldn’t guess the “f” in TfL, it’s Transport for London. https://tfl.gov.uk/ https://tfl.gov.uk/ https://en.wikipedia.org/wiki/Transport_for_London https://en.wikipedia.org/wiki/Transport_for_London
- moomin 1y ago
  You can blame Blair, I think, for the fashion of putting “for” into the names of administrative organisations.
  - AStonesThrow 1y ago
    Indeed, the Department for Transport was renamed in 1997, and TfL followed suit in 2000. There is a minor fandom controversy over the Ministry of Magic in the Wizarding World and whether the "Ministry for Magic" and "Minister for Magic" are valid alternate terms, but I have only identified one instance where JK Rowling wrote it this way, and it was outside the novels. Canonically, Harry turned 17 in 1997, so I suppose Tony Blair's reforms wouldn't apply post-Voldemort. However, Platform 9¾ is now "properly labelled" in the Muggles' King's Cross Station. https://commons.wikimedia.org/wiki/File:Cmglee_London_Kings_Cross_Platform_9_3_4.jpg https://commons.wikimedia.org/wiki/File:Cmglee_London_Kings_... Travellers should also mind the gap between "TfL" and "TLF Travel Alerts", a defunct account which was part of Weird Twitter, and somewhere I hope I can dig up an archive, because the daily alerts were comic genius in 140 characters or less. https://commons.wikimedia.org/wiki/File:Paddington_Bear_Statue.jpg https://commons.wikimedia.org/wiki/File:Paddington_Bear_Stat... The arrival of Paddington Bear from Darkest Peru may be partly explained by the heating of the Tube stations. He surely would be right at home in a dark, humid and warm environment. My mother encouraged me to read about Paddington Bear, and in 2008 I was privileged to have a layover in Westminster, where I passed through Paddington Station and totally missed out on visiting the Paddington Bear statue therein. But I was able to purchase a refrigerator magnet bearing the "MIND THE GAP" official logo, which I presented to her in gratitude.
- devnullbrain 1y ago
  In case you missed the 4 places it's made explicit in the graphs, or 'London' in the URL.
pfdietz 1y ago
This problem is also an illustration of the potential of geological thermal energy storage. The thermal time constant of a lump of matter scales as the square of its linear dimensions (for a given geometry). This can easily reach many years for large enough chunks of underground stuff. This is why geothermal energy works at all; the heat energy flowing up from the deep earth is stored for many thousands of years at reachable depths and can be mined. And, if one has excess energy, it could be reinjected underground as heat and later recovered.
- fy20 1y ago
  I live in a country where summers are warm and winters are cold. One idea I've thought about is why we don't just have massive water tanks under our houses. Energy can be dumped in during the summer for cooling, and taken out during winter for heating. It would be more efficient that ground source geothermal as it's a closed loop system, so heat won't leak away. My house needs around 2500kWh per year, so you'd need a tank of around 100,000 litres. That is 8x8x1.5 metres - basically a small basement. To get that energy out youd need to heat it to 60c in the summer, and it would cool to 30c in the winter. You could even do that with passive water flow, no heat pumps needed.
  - pfdietz 1y ago
    Or, you could flow heat transfer fluid through buried pipes and let the soil or rock around the pipes retain the heat. This is the idea behind geothermal heat pumps. The obstruction to doing this is cost.
deleted 1y ago
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aaron695 1y ago
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zeristor 1y ago
I had an idea, perhaps a weird fantasy. Of a special tube train with blocks of ice. You’d need to have various pits dug in, and pumps to drain the water. Yes water and power electronics is “fraught”. I just like the idea of trains trundling along, blocks of ice being carted out and gradually melting. Another idea is to move mechs-bots via Underground in a post-apocalyptic scenario, but that’s not so relevant here.
- laurencerowe 1y ago
  This was actually tried: https://www.theguardian.com/uk/2007/jun/05/transport.world https://www.theguardian.com/uk/2007/jun/05/transport.world
- LeoPanthera 1y ago
  This would also increase the humidity to swamp-like levels.
  - zeristor 1y ago
    Not if it was kept separate a metal box with fins could absorb the heat without leaking any humidity. Besides at that temperature, more water can be absorbed in the air, so not just latent heat of melting, but heat absorbed in evaporation too. Of course that would have to be wafted out, and not pumped were it just water.
- surfingdino 1y ago
  Various fungi would love it.
- Cthulhu_ 1y ago
  But then they'd spend more energy (and more braking) hauling that ice around; would the amount of heat absorbed be more than the one ice train would generate? There's probably more efficient materials to use, big lumps of supercooled metal. Someone else mentioned liquid air, that could just be evaporated in the tunnels and stations. Of course, generating liquid air costs a lot of energy too. I'm sure the problem is easily solved if you assume infinite and free energy.
Havoc 1y ago
Is there a reason why they can't drill a couple bowling ball sized holes at strategic intervals and put some high speed extraction fans in? Stations entrances are open to outside so if you create enough negative pressure the hottest parts in the tunnels it'll pull in air. Do that long enough and presumably ambient & clay cools? Presumably engineers dismissed this already, but why?
- CorrectHorseBat 1y ago
  They have added ventilation to the tunnels, it's mentioned in the article. It's more than just a couple bowling sized holes, but apparently still not enough
  - thyristan 1y ago
    Unfortunately, hydrating clay is extremely hard to do. Clay is what you use as a water-tight material in dams, artificial lakes, waste dumps and stuff like that, because water doesn't really pass through it.
    - CorrectHorseBat 1y ago
      I think you replied to the wrong comment?
      - thyristan 1y ago
        Yes, sorry.
- avianlyric 1y ago
  I think people might object to TfL drilling a bowling ball sized tunnel in the middle of their house/garden/park/road/driveway/swimming pool/historic monument. Remember the deep level network is some 23m down, and runs under buildings. At lot of it doesn’t follow roads, or have any kind of conveniently clear space on the surface above it.
- mike_hearn 1y ago
philjohn 1y ago
Yep ... know people who commute on the Victoria and it doesn't sound fun. I've had to get it when my usual commute on the Northern line was impossible (only once, thankfully) and it was horrendous. And the Northern line is no picnic either.
gilbertjolly 1y ago
This is a generational buildup of heat, being tackled seasonally. TfL must run its cooling operations in the winter as well as the summer. It’s about net energy difference over the whole year. Finding cold air in the winter will also be substantially cheaper
- MichaelZuo 1y ago
  I dont quite understand what’s stopping them from just buying hundreds of chillers, putting them on the surface close to each station, and running chilled water loops down. Other than cost of course.
  - mnw21cam 1y ago
    They're running trains. Trains use a lot of electricity, and they turn almost all of it into heat. You'd have to have as much chilling capacity as the current electricity demand of the entire tube line, which is quite a lot. However, if the buildings above were to sink ground source heat pump loops into the warmed ground to heat the buildings in winter, this would basically be what you just suggested, and would be a win-win situation.
    - MichaelZuo 1y ago
      Huh? Modern modular air cooled chillers go up to 800 tons each and can remove multiple MW of heat load continuously pretty much 24/7. 500 of them could remove 1.4 GW of heat. Of course there are many ways to improve efficiency, but even assuming the worst case it’s still technically feasible to remove many times more heat than the line generates.
      - avianlyric 1y ago
        And where is the energy to power all of them coming from? GP is saying that you can approximate the energy going into the system by looking at the electricity consumption of the trains, as all then energy is eventually going to end up as heat. A heat pump can have a CoP topping out at 5. So 1 unit of energy needed to move 5 units heat out. That means a “net zero” cooling system would consume a minimum of 20% as much energy as the trains themselves. Realistically it’s probably closer to a CoP of 3.5, so 28% more energy. For something like the underground that gonna be a 5-10% increase in there operational costs at a minimum. Where does the funding for all that come from? And that before we even look at the capital costs of heat pumps and various ancillary equipment needed to run them. As a point of reference TfL underground trains have an average power consumption of 140MW continuous. Now only about 45% of the underground is actually underground, but that’s still 63MW in just the underground parts. At an optimistic CoP of 5, that means 12.6MW of additional energy needed to cool the tunnels using your approach. Wholesale electricity prices in the UK are something like 7p per kWh. So over a year that’s an additional £17m of electricity, just for cooling.
lysace 1y ago
Using the London subway is an adventure. https://www.bbc.com/news/articles/cy9xxlky2pno https://www.bbc.com/news/articles/cy9xxlky2pno (2024) > Phone signal goes live on 25% of underground Tube
isaacremuant 1y ago
Losing the battle or not even trying to fight? It's
sour-taste 1y ago
What if trains brought their heat with them instead of leaving it in the tunnels? I'm thinking some kind of large seal like thing in front of and behind trains that keeps the train surrounded by the same air. Stations serve as a spot to dump hot air and blow in cooler air. I guess the problem is it would take a lot of energy to push all that air around. Also the trains would be hotter.
- throwanem 1y ago
  Also you'd blow everyone off the platform, up the escalator, and a hundred feet in the air at each station stop.
  - sour-taste 1y ago
    That... Is a hilarious and good point. You could seal the stations like they do on the Elizabeth line but it's still a stupid idea. I just got back from London actually and am still incredibly jet lagged, for which I blame my suggestion
    - throwanem 1y ago
      Oh, don't apologize. I cackled at the thought - what a commute! And for a way to cool off after being baked in the tube like a jacket potato, I can hardly think what'd work better.
  - myself248 1y ago
    At that point you don't need trains. Just don your Zorb ball, choose the appropriate shaft, and dive into the air stream.
- lmm 1y ago
  The Victoria line trains only stop briefly at the stations and are underground the entire time. For other lines TfL has air conditioning systems that capture heat during the underground sections and then dump it in the open-air parts, but that won't work for the Victoria line.
- 1y ago
ggm 1y ago
So if I have this right, TfL is constructing a giant thermal mass, and therefore is banking heat energy. If we (for example) piped cold water through this, we'd get warm water. So in winter, this could reduce heating bills substantially for people connected to such a system. Is TfL not monetising this thermal mass? Why not?
- SoftTalker 1y ago
  30 degree water isn’t warm enough for direct residential heating but with a geothermal system it’d be great.
  - fy20 1y ago
    Actually it is. My house has radiant underfloor heating built into the concrete slab, and the water runs through at 30c. Keeps it a toasty 24c when it's -20c outside.
  - HighGoldstein 1y ago
    However heating 30C water to the desired temperature is cheaper than heating 10C water
- throwanem 1y ago
  Steam heat at 30°? In London? Can't imagine...
  - ggm 1y ago
    London had both water, and air pressure delivery systems embedded in the street scape to manage cranes at the docks, machinery and for letter delivery. Heating and cooling benefits from remarkably small differences in temp. Thats how heat pumps work. And, lifting the input temp by only 5-10 degrees C can make a huge difference to the energy required to get to the next level. It takes about 200Kj to heat 1L of water from 10C to 60C and 125Kj to heat it from 30C to 60C -A 37.5% saving in energy inputs. You better believe a corporate would seek a 1/3 reduction in energy input costs. (my sarcasm meter is broken sorry if I ruined a joke)
zeristor 1y ago
At what point does it become illegally warm? I thought 30°C was the limit for office work in the UK. I recall when there was a terrorist bombing for the Stratford Olympics that emergency service people had to work in a tunnel at 60°C. I avoided the deep tube for several years after that.
- normie3000 1y ago
  > I recall when there was a terrorist bombing for the Stratford Olympics Was there? I don't recall the event, and can't find references on google.
  - zeristor 1y ago
    Sorry, I meant there was a terrorist bombing for the announcement of the Olympics at Stratford. I left the word ‘for’ do a lot. I had assumed that it was infamous enough not to require much more detail, has it really been that long ago that people didn’t know about it. https://www.btp.police.uk/police-forces/british-transport-police/areas/about-us/about-us/our-history/london-bombings-of-2005/ https://www.btp.police.uk/police-forces/british-transport-po... It seems I had muddled the name, I meant to say the tunnel by Russell Square tube station. Coming up to years ago in a few months… https://www.bbc.com/news/uk-33253598.amp https://www.bbc.com/news/uk-33253598.amp
    - normie3000 1y ago
      > Coming up to years ago in a few months… 20 years I've never heard 7/7 associated with the olympics before.
- antidumbass 1y ago
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afsdef3f3wafew 1y ago
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joshka 1y ago
> The Senior Press Officer added that with many stations in close succession, the Victoria and Central lines experience frequent acceleration and braking, contributing to heat buildup within the tunnels. I'm sure that this is probably one of those stupid suggestions that shows a lack of understanding of the problem, but could skipping stations help help this? Something like the following gets you 1/3rd less braking energy released into the tunnels: Station ABCDEFGH Train1 .. .. .. Train2 .. .. . Train3 . .. .. Taking a look at the peak time schedules they have trains coming every 2 minutes, so this seems like it would be reasonable for most people to have to sometimes wait 6 minutes for the right train, but generally not more than 4.
- aldonius 1y ago
  With frequent trains and close stop spacing you've plausibly got a situation where each train is entering and leaving each station at about the same time? So skip-stop might not save much acceleration/braking.
- lmm 1y ago
  Probably not, because the limiting factor on train throughput is remaining a safe braking distance behind the train in front. If the train in front of you has stopped at station D then you need to stop in station C even if you don't open the doors. (You could get around that by running the trains further apart, but that would be a critical loss of capacity).
  - aeyes 1y ago
    There are some metro lines which use this skip-stop system, the distance between trains is created by staying longer in the station. https://en.wikipedia.org/wiki/Skip-stop https://en.wikipedia.org/wiki/Skip-stop
    - lmm 1y ago
      Right but the Victoria line puts a lot of effort into keeping station stop time to a minimum for the sake of capacity (it's the most intensive metro line in London, at 36-37tph, and one of the most intensive in the world). One way or another you have to space the trains out more to do skip-stopping.
f_allwein 1y ago
In the longer run, give up the old deep tube lines. They could be gradually replaced by Elizabeth Line-style tracks (larger capacity, fewer stops, good air conditioning).
- jurip 1y ago
  Doesn't Elizabeth run even deeper than the current ones, though? Certainly seemed so in the elevators of the Whitechapel station. And it's not like you could replace the current lines without building the new one first and I bet there isn't too much empty space between the surface and the existing lines.
Peteragain 1y ago
Why is the London underground so warm? Where is the heat coming from? Most underground locations are cooler in hot places in my experience. Is it just people?
- gspr 1y ago
  https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling
  - Peteragain 1y ago
    Interesting. My question was one others had asked - so much so that the answer has it's own Wikipedia page with a table! It looks as if regenerative breaking on the trains would fix the problem.
- Mashimo 1y ago
  You could read the linked article ;-) It's one of the oldest metro (retrofit cooling), it's deep, high usage, it's surrounded by isolating clay, dense city.
zeristor 1y ago
One key question is that with the construction of the Elizabeth line, and this being a known issue how was that designed and built differently to solve this problem, assuming it has fixed it. Update: There’s not a huge amount, but with careful search term tweaking I did find this on the Elizabeth line thermal loads: https://learninglegacy.crossrail.co.uk/documents/the-design-of-thermal-tunnel-energy-segments-for-crossrail/ https://learninglegacy.crossrail.co.uk/documents/the-design-...
- eszed 1y ago
  I had the same idea as proposed in this paper: dump tunnel heat into nearby buildings. Win-win! However: > This paper for a possible energy segment installation was written during the design phase but the proposal was not implemented. Bleah.
bob1029 1y ago
Why not look at it like a nuclear power plant and build a similar solution? You can reject gigawatts of power with one wet cooling tower. If pumping water up and down that distance is infeasible, then make the primary coolant loop use a phase change refrigerant. Much easier to pump long vertical distances. Condensed fluid would flow down with gravity, evaporated gas would flow up.
- saagarjha 1y ago
  Probably because the temperature gradient isn't enough for it to be worth it
walthamstow 1y ago
Am I the only person who thinks 31C is not actually that warm for August on the only line that is entirely underground?
- acrooks 1y ago
  Yes. As somebody who has used dozens of metro systems around the world, it is literally the only one that is not ~room temperature. In the summer, it is so uncomfortable on the tube that I almost always take a taxi, even if a taxi is materially slower.
fdsafkas 1y ago
[dead]

125 points by zeristor 1y ago

Y_Y 1y ago

> Historically, the Underground infrastructure offered a respite from warm weather, indicated in Austin Cooper’s ‘It is cooler below’ poster, issued in 1924 by the Underground group to promote a more comfortable experience of travel during warm weather. A century of burrowing commuter-worms unfortunately managed to bake all the beautiful wet clay that kept the tunnels tolerable when the sun was shining about. It seems straightforward to me that it would be enough to rehydrate the ground. Just need (approximately), 400km of track * 25m average depth * 3m tunnel width * 20% moisture content of wet clay = 6 billion litres of water Sounds like a lot but it's only about 1/300th of the yearly flow of the Thames.

lloydatkinson 1y ago
Have you thought of suggesting this to TfL? There has to be something here.
- thyristan 1y ago
  Unfortunately, hydrating clay is extremely hard to do. Clay is what you use as a water-tight material in dams, artificial lakes, waste dumps and stuff like that, because water doesn't really pass through it.
- rjh29 1y ago
  Yes, people whose day job is to explore all possible options have surely missed this extremely obvious idea.
  - lloydatkinson 1y ago
    Alright smart arse.
  - mike_hearn 1y ago
    In fairness, TfL ran a public competition to source cooling ideas some years ago, so the people whose day job is to explore all the possibilities clearly felt like they were out of ideas.
- Y_Y 1y ago
  It was just a bit of a shower thought to be honest, but it looks like there are cleverer and more responsible people who've considered similar schemes. As I posted in a cousin comment, I found this nice blog post examining some of the more serious ideas, including water-cooling: https://www.ianvisits.co.uk/articles/cooling-the-london-underground-220/ https://www.ianvisits.co.uk/articles/cooling-the-london-unde...
heisenzombie 1y ago
<man walks into sauna room> Ooh, it's a bit hot in here! I better throw some water on these rocks to cool them down. Joking aside, I actually don't know how dry it is in the underground, and therefore whether adding water for evaporative cooling would work. I would have assumed it was quite humid, but maybe not?
- Cthulhu_ 1y ago
  It would be if they tried cooling it with water, for sure; evaporative cooling would only work if there's enough airflow, else they'd just get 100% humidity so it would be both hot and humid.
ajb 1y ago
It seems implausible to me that the clay is dehydrated. The Victoria line was only built in the 60s and has a waterproof lining. (It's also built with asbestos cement, unfortunately, which is no doubt a problem when they need to cut it for whatever reason)
- Y_Y 1y ago
  The cement can negatively effect the water retenction of the clay, as does of course the temperature. The water needn't seep into the tunnel, just be moved away from it to adjacted areas. There's a nice article here which goes into more detail: https://www.ianvisits.co.uk/articles/cooling-the-london-underground-220/ https://www.ianvisits.co.uk/articles/cooling-the-london-unde...
avianlyric 1y ago
I don’t think the hydration of the clay is the important element here. Rather I suspect it’s simple just the sheer mass of clay, wet or otherwise, that’s involved. There’s a reason why ground source heat pumps work so well. It’s because the ground is such a fantastically huge heat sink/source that in most scenarios we consider it capable of sinking or sourcing a practically unlimited amount of heat. Unfortunately one of the scenarios where this breaks down, is when you stick a bunch of tunnels in the ground, then pump a crap ton of energy into those tunnels years round, and expect the ground to sink all the heat away. Turns out, if you do that, the ground itself starts heating up, and given that clay is a reasonable good insulator, it’s like wrapping all those tunnels in wool jumpers. I would point out as well that all these tunnels are “deep level” tunnels running at an average depth of 24 meters and getting as low as 67 meters. The heat of the sun on the ground surface will have approximately zero impact on the tunnel temperatures. 24 meters of clay is a lot of insulation to work with.
- jjcob 1y ago
  I think you are right. The graph at the bottom of the article shows that temperatures dropped around 2020 (presumably less traffic due to the pandemic). So the ground can take up more heat, but it can't do it quickly enough.
- Y_Y 1y ago
  My original comment was meant to be tounge-in-cheek, but I would like to add the advantage of wet clay is really in its thermal conductivity[0] which is roughly two to four times higher than dry clay. It will also have higher thermal capacity, so that high frequency fluctuations (like day/night) will be smoothed out. [0] https://www.mdpi.com/2571-8789/8/2/47 https://www.mdpi.com/2571-8789/8/2/47 (I don't think my comment implied that the sunshine makes it hot in the tunnel, only that when it's hot above ground it's nice to be cool below, like in the poster. And I did include a figure of 25m for average depth, I've spent enough time on their endless stairs to know that the TfL delved to greedily and too deep. This spiral staircase has 320 steps, I shudder.)
zeristor 1y ago
At a couple of stations a river passes by and that is used to cool the station. I think Oxford Circus is one.
Theodores 1y ago
> Austin Cooper’s ‘It is cooler below’ poster As I see it, it is just a marketing problem with easy solutions. There is psychology and reverse psychology. You could fool people into embracing the heat by redecorating the stations and trains to make it a 'journey to hell, via the centre of the earth'. The stops south of the river could be marketed as Dante's inferno and hellish. Or you could go the other way, to make it kitch Hawaiian themed, so people expect the heat and to embrace it as a mini-holiday. Or, the stations could be redecorated as if it were a trip to the Antarctic, so people see images of penguins braving the ice, with murals from the Shackleton days, to imagine they are cold. In places like Moscow the underground train stations give the impression that people are in splendid palaces, this works pretty well. As I see it, TfL just need to up their decor game, problem solved.
- Affric 1y ago
  I hate that I think Theres a lot to this

azernik 1y ago

"The average temperatures on the Victoria line have risen by almost seven degrees since 2013 – nearly a *30%* increase. Conversely, the increase in the average annual temperatures across all Underground lines from 2013 to 2024 was merely *seven percent*, placing Victoria’s temperature rise vastly above that." Using percentages to talk about changes in non-Kelvin temperatures is crazy.

OJFord 1y ago
It would definitely be crazy in Fahrenheit, but in centigrade I think it makes some sort of intuitive (if not scientific) sense. (Together with the sea-level assumption we always make in casual temperature discussion anyway.)
- azernik 1y ago
  It makes just as much intuitive sense in Fahrenheit as it does in centigrade.
  - perching_aix 1y ago
    Why? The slope of the Fahrenheit scale is different to the Celsius and Kelvin scales, but the slope of the latter two does match.
    - meindnoch 1y ago
      Ok. Then please explain what % does the temperature rise when going from 0 Celsius to 5 Celsius!
      - stephencanon 1y ago
        Or -1 to 1 Celsius, for that matter.
        chihuahua 1y ago

chiph 1y ago

Looking at the temperature chart and the significant drop in 2020 during the pandemic, the source is certainly the trains and people themselves. (fewer trains moving, less heat added back then). At this point I expect the infrastructure is heat soaked and will need a prolonged period of cooling to bring temps down. i.e. don't expect instant results. Moving more air through the tunnels, adding A/C systems - both have a problem of needing room up on the surface for blowers and compressors, something that is hard to do in modern London. Tough problem.

meindnoch 1y ago
This. Brake friction pumps heat into the ground at a higher rate than it could dissipate away.
- eternauta3k 1y ago
  Aren't they using regenerative braking?
  - Zigurd 1y ago
    Some parts of the London underground use passive energy recovery by locating stations nearer to the surface than most of the tunnel between them. Trains start by rolling downhill and when they approach a station, uphill.
  - blipvert 1y ago
    Yes. https://tfl.gov.uk/corporate/transparency/freedom-of-information/foi-request-detail?referenceId=FOI-3010-2223 https://tfl.gov.uk/corporate/transparency/freedom-of-informa...
    - altairprime 1y ago
      > If the line is unreceptive, braking energy is dissipated in on-board resistors How many watts are dumped into onboard heat-generating resistors on the trains in the most heat-affected lines per week? Should regenerative braking be disabled in aboveground trains when heat impacts reach uncomfortable levels in belowground tunnels? > Regenerated braking energy is transmitted to the London Underground high voltage distribution network If regenerative braking oversupply is inducing higher temperatures belowground through on-train resistors, then only an operational change to aboveground mode would be required to minimize that induced heating during times of thermal need. (Obviously longer-term solutions with non-zero capital expenditure exist that could be pursued in parallel.)

randallsquared 1y ago

> Temperatures hiked as high as 31.1[C] degrees in August 2024 [...] So, I can imagine that this is a long-term problem, but it seems odd that the panic is setting in already, when some platforms in the NYC subway regularly exceed 40C / 104F every summer? This article seems in a similar genre to the breathless advice to remain inside in Britain when the outside temperature might get above 27C / 81F, otherwise known as a not-particularly-warm spring day in much of the US in most years.

masklinn 1y ago
> This article seems in a similar genre to the breathless advice to remain inside in Britain when the outside temperature might get above 27C / 81F, otherwise known as a not-particularly-warm spring day in much of the US in most years. It’s really not breathless, because high temperatures and how to handle them is completely absent from the cultural baggage. I don’t live in the UK, but in a place which similarly does not have much in the way of high temperatures historically and low AC penetration, and during heat spikes I see a significant fraction of my neighbours with windows wide open at 4PM. Habituation is also a significant factor. The UK does not get a smooth transition into higher normals, it gets heatwaves.
- tim333 1y ago
  I live in the UK and a lot is down to the tabloid newspapers trying to get some sales with 'Horror Heatwave!' type headlines when it's 27C. Brits go on holiday to Spain, we are familiar with heat.
  - tialaramex 1y ago
    Statistically we know that humans who live somewhere that you'll just die in the regular environment due to climate behave very differently from humans who live in a temperate climate like the UK when the actual temperature warrants the same behaviour. If you live in Nunavut or the Iran / Pakistan border you already knew that you can just die from temperature extremes and so you need to ensure you stay at a survivable temperature, in Wales it's quite unexpected. As a result you actually get many more deaths from extremes in countries where the usual climate is temperate like Britain, even when the actual temperatures aren't as extreme as in countries where that would be more common.

cherryteastain 1y ago

> tunnel ventilation installations, chiller systems pumping chilled air into mid-tunnel shafts and regenerative braking to reduce heat generated by trains breaking The hoops TfL jumps through just to not extend AC to the rolling stock in more lines are baffling. At least we finally got some AC in the new Piccadilly rolling stock.

deleted 1y ago
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pitaj 1y ago
AC will only make the problem worse in the long term. Picadilly got AC because it has above-ground sections.
- cherryteastain 1y ago
  You can redesign the signalling systems etc to work at even 40C, plenty of countries do it. You can't redesign humans to feel comfortable inside a stuffy carriage at 35C.
  - crote 1y ago
    Sure, but that means the stations will also have 40C air. Can the humans handle that? And it's going to be 42C the next year, 44C the year after, and so on...
    - FredFS456 1y ago
      Platform screen doors can isolate tunnel temperatures from platform temperatures.
      - andylynch 1y ago
        That doesn't help the people maintaining the tunnels and everything inside them.
  - 1y ago

Aachen 1y ago

Isn't heat free energy in a place like London? I know very little about metro systems so please correct me if this is insane: wouldn't the people living above the tubes be happy to get a heat exchanger (passive) or heat pump (active, but takes more of the heat) that prewarms their hot water supply? People still take warm showers and boil tea and rice/pasta in summer, and in winter the purpose should be obvious. If the water comes in at 30 instead of 10 degrees C, you need to add only a few degrees for showers and floor heating

joshlk 1y ago
What do you do in the summer when the homes don’t want the heat?
- jairuhme 1y ago
  People still take hot showers and use hot water
- crote 1y ago
  That doesn't have to be a problem in practice. The entire issue is that the earth surrounding the tubes is acting as a giant buffer. Enough heat has been dumped into it over the years that it has permanently warmed up. Draw heat from it during the winter to warm up homes, and it'll be able to absorb more heat from the tunnel air during the summer.
  - TheOtherHobbes 1y ago
    And because it's permanently warmed up, the long term consequence is the line becomes a health hazard and has to be closed for increasingly long periods. When wet bulb > body temp people start getting heat stroke, which leads to fainting and potentially death - a bad look for a public transport system. The likely remedy is to install gigantic refrigeration units in the ventilation shafts and pump in cold air. This will be hugely expensive to build and run. But the alternative is a tube line that can't be used. So there may not be much choice.
- 1y ago

brightbeige 1y ago

In case you also couldn’t guess the “f” in TfL, it’s Transport for London. https://tfl.gov.uk/ https://tfl.gov.uk/ https://en.wikipedia.org/wiki/Transport_for_London https://en.wikipedia.org/wiki/Transport_for_London

moomin 1y ago
You can blame Blair, I think, for the fashion of putting “for” into the names of administrative organisations.
- AStonesThrow 1y ago
  Indeed, the Department for Transport was renamed in 1997, and TfL followed suit in 2000. There is a minor fandom controversy over the Ministry of Magic in the Wizarding World and whether the "Ministry for Magic" and "Minister for Magic" are valid alternate terms, but I have only identified one instance where JK Rowling wrote it this way, and it was outside the novels. Canonically, Harry turned 17 in 1997, so I suppose Tony Blair's reforms wouldn't apply post-Voldemort. However, Platform 9¾ is now "properly labelled" in the Muggles' King's Cross Station. https://commons.wikimedia.org/wiki/File:Cmglee_London_Kings_Cross_Platform_9_3_4.jpg https://commons.wikimedia.org/wiki/File:Cmglee_London_Kings_... Travellers should also mind the gap between "TfL" and "TLF Travel Alerts", a defunct account which was part of Weird Twitter, and somewhere I hope I can dig up an archive, because the daily alerts were comic genius in 140 characters or less. https://commons.wikimedia.org/wiki/File:Paddington_Bear_Statue.jpg https://commons.wikimedia.org/wiki/File:Paddington_Bear_Stat... The arrival of Paddington Bear from Darkest Peru may be partly explained by the heating of the Tube stations. He surely would be right at home in a dark, humid and warm environment. My mother encouraged me to read about Paddington Bear, and in 2008 I was privileged to have a layover in Westminster, where I passed through Paddington Station and totally missed out on visiting the Paddington Bear statue therein. But I was able to purchase a refrigerator magnet bearing the "MIND THE GAP" official logo, which I presented to her in gratitude.
devnullbrain 1y ago
In case you missed the 4 places it's made explicit in the graphs, or 'London' in the URL.

pfdietz 1y ago

This problem is also an illustration of the potential of geological thermal energy storage. The thermal time constant of a lump of matter scales as the square of its linear dimensions (for a given geometry). This can easily reach many years for large enough chunks of underground stuff. This is why geothermal energy works at all; the heat energy flowing up from the deep earth is stored for many thousands of years at reachable depths and can be mined. And, if one has excess energy, it could be reinjected underground as heat and later recovered.

fy20 1y ago
I live in a country where summers are warm and winters are cold. One idea I've thought about is why we don't just have massive water tanks under our houses. Energy can be dumped in during the summer for cooling, and taken out during winter for heating. It would be more efficient that ground source geothermal as it's a closed loop system, so heat won't leak away. My house needs around 2500kWh per year, so you'd need a tank of around 100,000 litres. That is 8x8x1.5 metres - basically a small basement. To get that energy out youd need to heat it to 60c in the summer, and it would cool to 30c in the winter. You could even do that with passive water flow, no heat pumps needed.
- pfdietz 1y ago
  Or, you could flow heat transfer fluid through buried pipes and let the soil or rock around the pipes retain the heat. This is the idea behind geothermal heat pumps. The obstruction to doing this is cost.

deleted 1y ago

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aaron695 1y ago

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zeristor 1y ago

I had an idea, perhaps a weird fantasy. Of a special tube train with blocks of ice. You’d need to have various pits dug in, and pumps to drain the water. Yes water and power electronics is “fraught”. I just like the idea of trains trundling along, blocks of ice being carted out and gradually melting. Another idea is to move mechs-bots via Underground in a post-apocalyptic scenario, but that’s not so relevant here.

laurencerowe 1y ago
This was actually tried: https://www.theguardian.com/uk/2007/jun/05/transport.world https://www.theguardian.com/uk/2007/jun/05/transport.world
LeoPanthera 1y ago
This would also increase the humidity to swamp-like levels.
- zeristor 1y ago
  Not if it was kept separate a metal box with fins could absorb the heat without leaking any humidity. Besides at that temperature, more water can be absorbed in the air, so not just latent heat of melting, but heat absorbed in evaporation too. Of course that would have to be wafted out, and not pumped were it just water.
surfingdino 1y ago
Various fungi would love it.
Cthulhu_ 1y ago
But then they'd spend more energy (and more braking) hauling that ice around; would the amount of heat absorbed be more than the one ice train would generate? There's probably more efficient materials to use, big lumps of supercooled metal. Someone else mentioned liquid air, that could just be evaporated in the tunnels and stations. Of course, generating liquid air costs a lot of energy too. I'm sure the problem is easily solved if you assume infinite and free energy.

Havoc 1y ago

Is there a reason why they can't drill a couple bowling ball sized holes at strategic intervals and put some high speed extraction fans in? Stations entrances are open to outside so if you create enough negative pressure the hottest parts in the tunnels it'll pull in air. Do that long enough and presumably ambient & clay cools? Presumably engineers dismissed this already, but why?

CorrectHorseBat 1y ago
They have added ventilation to the tunnels, it's mentioned in the article. It's more than just a couple bowling sized holes, but apparently still not enough
- thyristan 1y ago
  Unfortunately, hydrating clay is extremely hard to do. Clay is what you use as a water-tight material in dams, artificial lakes, waste dumps and stuff like that, because water doesn't really pass through it.
  - CorrectHorseBat 1y ago
    I think you replied to the wrong comment?
    - thyristan 1y ago
      Yes, sorry.
avianlyric 1y ago
I think people might object to TfL drilling a bowling ball sized tunnel in the middle of their house/garden/park/road/driveway/swimming pool/historic monument. Remember the deep level network is some 23m down, and runs under buildings. At lot of it doesn’t follow roads, or have any kind of conveniently clear space on the surface above it.
mike_hearn 1y ago

philjohn 1y ago

Yep ... know people who commute on the Victoria and it doesn't sound fun. I've had to get it when my usual commute on the Northern line was impossible (only once, thankfully) and it was horrendous. And the Northern line is no picnic either.

gilbertjolly 1y ago

This is a generational buildup of heat, being tackled seasonally. TfL must run its cooling operations in the winter as well as the summer. It’s about net energy difference over the whole year. Finding cold air in the winter will also be substantially cheaper

MichaelZuo 1y ago
I dont quite understand what’s stopping them from just buying hundreds of chillers, putting them on the surface close to each station, and running chilled water loops down. Other than cost of course.
- mnw21cam 1y ago
  They're running trains. Trains use a lot of electricity, and they turn almost all of it into heat. You'd have to have as much chilling capacity as the current electricity demand of the entire tube line, which is quite a lot. However, if the buildings above were to sink ground source heat pump loops into the warmed ground to heat the buildings in winter, this would basically be what you just suggested, and would be a win-win situation.
  - MichaelZuo 1y ago
    Huh? Modern modular air cooled chillers go up to 800 tons each and can remove multiple MW of heat load continuously pretty much 24/7. 500 of them could remove 1.4 GW of heat. Of course there are many ways to improve efficiency, but even assuming the worst case it’s still technically feasible to remove many times more heat than the line generates.
    - avianlyric 1y ago
      And where is the energy to power all of them coming from? GP is saying that you can approximate the energy going into the system by looking at the electricity consumption of the trains, as all then energy is eventually going to end up as heat. A heat pump can have a CoP topping out at 5. So 1 unit of energy needed to move 5 units heat out. That means a “net zero” cooling system would consume a minimum of 20% as much energy as the trains themselves. Realistically it’s probably closer to a CoP of 3.5, so 28% more energy. For something like the underground that gonna be a 5-10% increase in there operational costs at a minimum. Where does the funding for all that come from? And that before we even look at the capital costs of heat pumps and various ancillary equipment needed to run them. As a point of reference TfL underground trains have an average power consumption of 140MW continuous. Now only about 45% of the underground is actually underground, but that’s still 63MW in just the underground parts. At an optimistic CoP of 5, that means 12.6MW of additional energy needed to cool the tunnels using your approach. Wholesale electricity prices in the UK are something like 7p per kWh. So over a year that’s an additional £17m of electricity, just for cooling.

lysace 1y ago

Using the London subway is an adventure. https://www.bbc.com/news/articles/cy9xxlky2pno https://www.bbc.com/news/articles/cy9xxlky2pno (2024) > Phone signal goes live on 25% of underground Tube

isaacremuant 1y ago

Losing the battle or not even trying to fight? It's

sour-taste 1y ago

What if trains brought their heat with them instead of leaving it in the tunnels? I'm thinking some kind of large seal like thing in front of and behind trains that keeps the train surrounded by the same air. Stations serve as a spot to dump hot air and blow in cooler air. I guess the problem is it would take a lot of energy to push all that air around. Also the trains would be hotter.

throwanem 1y ago
Also you'd blow everyone off the platform, up the escalator, and a hundred feet in the air at each station stop.
- sour-taste 1y ago
  That... Is a hilarious and good point. You could seal the stations like they do on the Elizabeth line but it's still a stupid idea. I just got back from London actually and am still incredibly jet lagged, for which I blame my suggestion
  - throwanem 1y ago
    Oh, don't apologize. I cackled at the thought - what a commute! And for a way to cool off after being baked in the tube like a jacket potato, I can hardly think what'd work better.
- myself248 1y ago
  At that point you don't need trains. Just don your Zorb ball, choose the appropriate shaft, and dive into the air stream.
lmm 1y ago
The Victoria line trains only stop briefly at the stations and are underground the entire time. For other lines TfL has air conditioning systems that capture heat during the underground sections and then dump it in the open-air parts, but that won't work for the Victoria line.
1y ago

ggm 1y ago

So if I have this right, TfL is constructing a giant thermal mass, and therefore is banking heat energy. If we (for example) piped cold water through this, we'd get warm water. So in winter, this could reduce heating bills substantially for people connected to such a system. Is TfL not monetising this thermal mass? Why not?

SoftTalker 1y ago
30 degree water isn’t warm enough for direct residential heating but with a geothermal system it’d be great.
- fy20 1y ago
  Actually it is. My house has radiant underfloor heating built into the concrete slab, and the water runs through at 30c. Keeps it a toasty 24c when it's -20c outside.
- HighGoldstein 1y ago
  However heating 30C water to the desired temperature is cheaper than heating 10C water
throwanem 1y ago
Steam heat at 30°? In London? Can't imagine...
- ggm 1y ago
  London had both water, and air pressure delivery systems embedded in the street scape to manage cranes at the docks, machinery and for letter delivery. Heating and cooling benefits from remarkably small differences in temp. Thats how heat pumps work. And, lifting the input temp by only 5-10 degrees C can make a huge difference to the energy required to get to the next level. It takes about 200Kj to heat 1L of water from 10C to 60C and 125Kj to heat it from 30C to 60C -A 37.5% saving in energy inputs. You better believe a corporate would seek a 1/3 reduction in energy input costs. (my sarcasm meter is broken sorry if I ruined a joke)

zeristor 1y ago

At what point does it become illegally warm? I thought 30°C was the limit for office work in the UK. I recall when there was a terrorist bombing for the Stratford Olympics that emergency service people had to work in a tunnel at 60°C. I avoided the deep tube for several years after that.

normie3000 1y ago
> I recall when there was a terrorist bombing for the Stratford Olympics Was there? I don't recall the event, and can't find references on google.
- zeristor 1y ago
  Sorry, I meant there was a terrorist bombing for the announcement of the Olympics at Stratford. I left the word ‘for’ do a lot. I had assumed that it was infamous enough not to require much more detail, has it really been that long ago that people didn’t know about it. https://www.btp.police.uk/police-forces/british-transport-police/areas/about-us/about-us/our-history/london-bombings-of-2005/ https://www.btp.police.uk/police-forces/british-transport-po... It seems I had muddled the name, I meant to say the tunnel by Russell Square tube station. Coming up to years ago in a few months… https://www.bbc.com/news/uk-33253598.amp https://www.bbc.com/news/uk-33253598.amp
  - normie3000 1y ago
    > Coming up to years ago in a few months… 20 years I've never heard 7/7 associated with the olympics before.
antidumbass 1y ago
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afsdef3f3wafew 1y ago

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joshka 1y ago

> The Senior Press Officer added that with many stations in close succession, the Victoria and Central lines experience frequent acceleration and braking, contributing to heat buildup within the tunnels. I'm sure that this is probably one of those stupid suggestions that shows a lack of understanding of the problem, but could skipping stations help help this? Something like the following gets you 1/3rd less braking energy released into the tunnels: Station ABCDEFGH Train1 .. .. .. Train2 .. .. . Train3 . .. .. Taking a look at the peak time schedules they have trains coming every 2 minutes, so this seems like it would be reasonable for most people to have to sometimes wait 6 minutes for the right train, but generally not more than 4.

aldonius 1y ago
With frequent trains and close stop spacing you've plausibly got a situation where each train is entering and leaving each station at about the same time? So skip-stop might not save much acceleration/braking.
lmm 1y ago
Probably not, because the limiting factor on train throughput is remaining a safe braking distance behind the train in front. If the train in front of you has stopped at station D then you need to stop in station C even if you don't open the doors. (You could get around that by running the trains further apart, but that would be a critical loss of capacity).
- aeyes 1y ago
  There are some metro lines which use this skip-stop system, the distance between trains is created by staying longer in the station. https://en.wikipedia.org/wiki/Skip-stop https://en.wikipedia.org/wiki/Skip-stop
  - lmm 1y ago
    Right but the Victoria line puts a lot of effort into keeping station stop time to a minimum for the sake of capacity (it's the most intensive metro line in London, at 36-37tph, and one of the most intensive in the world). One way or another you have to space the trains out more to do skip-stopping.

f_allwein 1y ago

In the longer run, give up the old deep tube lines. They could be gradually replaced by Elizabeth Line-style tracks (larger capacity, fewer stops, good air conditioning).

jurip 1y ago
Doesn't Elizabeth run even deeper than the current ones, though? Certainly seemed so in the elevators of the Whitechapel station. And it's not like you could replace the current lines without building the new one first and I bet there isn't too much empty space between the surface and the existing lines.

Peteragain 1y ago

Why is the London underground so warm? Where is the heat coming from? Most underground locations are cooler in hot places in my experience. Is it just people?

gspr 1y ago
https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling
- Peteragain 1y ago
  Interesting. My question was one others had asked - so much so that the answer has it's own Wikipedia page with a table! It looks as if regenerative breaking on the trains would fix the problem.
Mashimo 1y ago
You could read the linked article ;-) It's one of the oldest metro (retrofit cooling), it's deep, high usage, it's surrounded by isolating clay, dense city.

zeristor 1y ago

One key question is that with the construction of the Elizabeth line, and this being a known issue how was that designed and built differently to solve this problem, assuming it has fixed it. Update: There’s not a huge amount, but with careful search term tweaking I did find this on the Elizabeth line thermal loads: https://learninglegacy.crossrail.co.uk/documents/the-design-of-thermal-tunnel-energy-segments-for-crossrail/ https://learninglegacy.crossrail.co.uk/documents/the-design-...

eszed 1y ago
I had the same idea as proposed in this paper: dump tunnel heat into nearby buildings. Win-win! However: > This paper for a possible energy segment installation was written during the design phase but the proposal was not implemented. Bleah.

bob1029 1y ago

Why not look at it like a nuclear power plant and build a similar solution? You can reject gigawatts of power with one wet cooling tower. If pumping water up and down that distance is infeasible, then make the primary coolant loop use a phase change refrigerant. Much easier to pump long vertical distances. Condensed fluid would flow down with gravity, evaporated gas would flow up.

saagarjha 1y ago
Probably because the temperature gradient isn't enough for it to be worth it

walthamstow 1y ago

Am I the only person who thinks 31C is not actually that warm for August on the only line that is entirely underground?

acrooks 1y ago
Yes. As somebody who has used dozens of metro systems around the world, it is literally the only one that is not ~room temperature. In the summer, it is so uncomfortable on the tube that I almost always take a taxi, even if a taxi is materially slower.

fdsafkas 1y ago

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