5 ms·

air conditioned trains are an achivement in 2023?

by merth 3y ago

benjijay 3y ago
Adding AC units to trains which travel through tunnels with minimal clearance is the achievement - Can't make the trains any bigger and there's no room in the old ones to just tuck an HVAC in without make them even more cramped.
- SideburnsOfDoom 3y ago
  AC units dump the heat "outside" into the air. There is no outside in deep tunnels. Nowhere for the heat to go. The tunnels have already heated up over the decades. https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling It's not primarily about headroom.
- bluGill 3y ago
  Headroom is not an issue - there is plenty of room underneath the trains between the wheels. They then pump the cooled air up through the walls to where they want vents. Sometimes trains use the space between the wheels for passengers, but that has significant disadvantages and so should be avoided for subways (it is worth it for street running trams!),
thejsa 3y ago
Yes, given the size constraints of the deep-level Tube tunnels, which are much smaller than those for mainline trains; apparently developments in small air con systems have helped a fair bit here, fifteen odd years ago apparently it just wasn’t feasible.
- anonymous_sorry 3y ago
  Arguable the more fundamental problem is this. Air-con is a negative-sum game because it not 100% efficient. As well as moving heat from one place to another, it creates extra heat. Turn air-con on in an enclosed space, with nowhere to vent the exhaust, and that space just gets hotter. A small, deep tunnel is close to being an enclosed space. You might be able cool the train interior a bit, but the tunnel will get hotter. Meaning the air-con has to work harder. Meaning it generates more heat. The Picadilly line is already uncomfortably hot for a good part of the year (but far from the worst [1]). This includes the platforms. What this article says is that the trains themselves are lighter and more efficient, so less heat is generated by the motors and brakes. They argue that that gives them some heat budget to use on air-conditioning. As a whole, the new trains will generate roughly the same amount of heat as the old ones. So the tunnels and platforms will stay around the same (ie, too hot!), but the train interior will be comfortable. [1] https://www.standard.co.uk/news/london/tube-underground-london-temperature-hottest-b1103973.html https://www.standard.co.uk/news/london/tube-underground-lond...
  - SideburnsOfDoom 3y ago
    Yes, "Where to vent the waste heat" is 100% the fundamental problem. You can't beat the second law of thermodynamics. The tunnels have absorbed heat over the decades, venting yet more heat into the tunnels is not going to work. More space would make the engineering easier, but it's not the fundamental issue.
londons_explore 3y ago
London underground runs in a parallel universe where they are reinventing 60's tech. They only recently got cell service for example. 20 years after most of the rest of the worlds railways. Some lines don't even have that yet either!
- kmlx 3y ago
  the london tube dates from 1863. that explains most issues.
- walthamstow 3y ago
  Of all the things TFL could do to improve the tube, cell service would not even be close to top of my list. We've had WiFi on the platforms for about 10 years which is enough to send/receive whatsapp messages while the train is stopped. I'm not sure it's fair to dig out TFL for being backwards. They introduced the Oyster in 2003, something NYC didn't get until 2019.
  - londons_explore 3y ago
    Reliable comms everywhere allows fully centralized train control, with no employees on each train. You can use cameras to check no passengers are stuck in doors, on the track, or fighting in the carriages or platforms. Now you can redeploy the staff away from repetitive tasks of driving trains and supervising stations, and towards engineering a better service. Get the typical journey speed up from 12 mph up to 45 mph. Make one direction of all tracks an express route that only stops at one station in 10 and drives 60 mph through all the others. Modify the old tunnels with an extra rail on a wall or ceiling for places where the tunnel alignment can't do 60 mph.
    - walthamstow 3y ago
      Are you a railway engineer or in some other related field? Some of these suggestions sound a bit bizarre to a layman, especially considering your idea that the only thing standing in our way is 4G signal and reshuffling some staff. > Get the typical journey speed up from 12 mph up to 45 mph. So instead of 30 minutes from Walthamstow to Brixton it'll be 8 minutes? How is that possible? There are 16 stations, or 14 stops excluding the terminii. If you stop for 30secs at each, that's 7 minutes in itself. > Make one direction of all tracks an express route that only stops at one station in 10 and drives 60 mph through all the others So we would have an express lane in one direction and a stopping lane in the other? Why is that a good thing? To me an express service seems /slower/ than the status quo, because I would have to wait longer for the train that stops where I want it to.
bombcar 3y ago
Air conditioning a train in a tunnel is a trick, because the tunnels heat up and can’t dissipate heat well at all.
masklinn 3y ago
I don’t know if you’ve been to london, but if you’re a standard “modern” height for a man you can barely to not even stand straight in the deep tube trains. They are very very small, and limited by the tunnels which are absolutely tiny. I’m not surprised fitting air conditioning is a challenge, even ignoring the ventilation issues which are also massive.
- kmlx 3y ago
  a consequence of having the first subway in the world i think.
  - sofixa 3y ago
    Yep, same as many other things we take for granted in modern constructions, such as accessibility, good signage, enough space on stations and tunnels for easy flow of passengers, platform screen doors, etc. It's a no brainer when building today, but wasn't back then, and retrofitting is extremely complex and expensive.
  - rwmj 3y ago
    Dug "by hand": https://hornseyhistorical.org.uk/piccadilly-line-extension-part-two/ https://hornseyhistorical.org.uk/piccadilly-line-extension-p... https://en.wikipedia.org/wiki/Tunnelling_shield#Manual_shield_tunnelling https://en.wikipedia.org/wiki/Tunnelling_shield#Manual_shiel...
- arethuza 3y ago
  You should see the Glasgow Subway - its trains are almost comically small.
  - jjgreen 3y ago
    The entire network is a single line which circles the city, the map shows 2 lines, one clockwise, one anticlockwise. The trains have a dirty orange livery, hence the local name: The Clockwork Orange. My favourite underground in the UK.
Nextgrid 3y ago
It's a huge achievement considering both the technical challenges (which other comments explain) but also that anything actually got done considering the UK's economic and political disaster.
- kmlx 3y ago
  > UK's economic and political disaster. i really don’t understand where this myth is coming from. do people seriously think the UK is an “economic disaster”? https://data.worldbank.org/?locations=DE-GB-FR https://data.worldbank.org/?locations=DE-GB-FR and here are the numbers for 2023: https://commonslibrary.parliament.uk/research-briefings/sn02784/ https://commonslibrary.parliament.uk/research-briefings/sn02...
  - walthamstow 3y ago
    I don't think it's a myth. The UK is actually two economies. It's basically southern Italy with NYC bolted onto it. The average numbers like those you've posted include London and look basically OK, but the London effect is hiding a lot. Take out London and the rest of the UK is an economic basket case with low education levels, high rents, rapidly aging citizens, low wages, low investment, low productivity, a small tax base and a public estate in poor condition. This was a really interesting piece on the matter, in fact most of Murdoch's work for the FT is excellent https://www.ft.com/content/e5c741a7-befa-4d49-a819-f1b0510a9802 https://www.ft.com/content/e5c741a7-befa-4d49-a819-f1b0510a9... If you don't have a way to access the FT, this chart encapsulates my point quite well https://www.ft.com/__origami/service/image/v2/images/raw/ftcms%3A11abf22a-c668-4a1e-ab54-6801ce23db96?source=next-article&fit=scale-down&quality=highest&width=700&dpr=2 https://www.ft.com/__origami/service/image/v2/images/raw/ftc...
    - TheOtherHobbes 3y ago
      London itself is very divided. There's plenty of money in a few select areas, but wastelands of poverty around them. The UK has a huge reservoir of natural talent which it's doing its best to destroy. Plastic populism suits the ruling class much better than invention and originality.
bowsamic 3y ago
Here in Hamburg the S-Bahns are only just being replaced by air conditioned models. I don't think there are even plans for an air conditioned U-Bahn yet
anonymous_sorry 3y ago
It's best to read the article to understand why.
SideburnsOfDoom 3y ago
Where would the waste heat go? Air Conditioning units dump the heat "outside" into the air. But there is no "outside" in deep tunnels. Worse, Air Con has to work to move heat, which creates more heat. You can't even break even. See the 2nd law of Thermodynamics.(1) It's not so much "air con on trains" but "air con in deep tunnels without a vent". There is nowhere for the heat to go, and the tunnels have already warned up over the decades. (2) > Conventional air conditioning was initially ruled out on the deep lines because of the lack of space for equipment on trains and the problems of dispersing the waste heat these would generate. Every solution is a costly compromise. e.g. drilling a new vent to the surface is theoretically possible, but very hard in a densely populated and built-up area. A lot of comments talk about tunnel size, which is a minor factor: Everything's easier to engineer when you have more space. But fundamentally the issue is where to send the waste heat, not "tunnel too small". 1) https://en.wikipedia.org/wiki/Laws_of_thermodynamics https://en.wikipedia.org/wiki/Laws_of_thermodynamics 2) https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling
- zeristor 3y ago
  Couldn’t they make some spaces, and a drain and bring in large blocks of ice to take heat out? I’m guessing water would be creating more problems. But it’s a train line, bringing in large blocks of ice should be simple.
dwroberts 3y ago
The challenge here is specific to this line - other lines (like Circle) already have AC on the trains - mainly because they’re absolutely huge trains by comparison
- rjmunro 3y ago
  London 2 main types of underground line: Subsurface (Circle, District, Metropolitan and Hammersmith and City lines), and tube. The subsurface lines were constructed by cut and cover and were made for steam engines. They are much larger than the tube lines. The Tube lines are tunnelled, and designed for electric power only. It's not really the size of the trains that allows AC on the subsurface lines, it the fact that the lines are well ventilated to allow steam and smoke from steam engines to escape.
  - dwroberts 3y ago
    Even the article specifically points out the size of the train as an issue > To fit air conditioning into the trains has been rather an interesting challenge, as air conditioning units are large and tube trains are small, and Siemens Mobility has taken several ideas and put them together to create the space needed.
Cthulhu_ 3y ago
It is here; they're small trains and the tunnels are very warm already, so the AC isn't as efficient, and adding more heat to the tunnels (which all comes from the running trains) will make it more inhospitable. There are some projects underway to try and cool the tunnels, but they're deep underground and have accumulated heat over decades.
DoughnutHole 3y ago
Air conditioning in a busy 19th century underground tunnel system is absolutely an achievement. Air conditioning an underground train means pumping that hot air into the tunnels. The tunnels have insufficient ventilation because this wasn't conceived of as a problem when many of them were built, and that's a challenge to rectify. There's also the issue that the trains are already making the tunnels too hot. 4000 trains running back and forth generates a lot of heat from both the engines and braking friction. That heat goes into the clay of the tunnel and is very slow to dissipate due to the high heat capacity of the clay. The trains are never stopped for long enough for the temperature to drop, and so the temperature of the clay has slowly risen 5-12 degrees depending on the line from when the first line was dug in 1863. Air conditioning the carriages of the new trains didn't result from any developments in air conditioning technology, but from breakthroughs reducing the thermal output of the engines and brakes. This gives them a heat "budget" letting them air condition the carriages without outputting any more heat into the tunnels than a standard train.
- deleted 3y ago
  [deleted]

air conditioned trains are an achivement in 2023?

by merth 3y ago

air conditioned trains are an achivement in 2023?

Adding AC units to trains which travel through tunnels with minimal clearance is the achievement - Can't make the trains any bigger and there's no room in the old ones to just tuck an HVAC in without make them even more cramped.

SideburnsOfDoom 3y ago
AC units dump the heat "outside" into the air. There is no outside in deep tunnels. Nowhere for the heat to go. The tunnels have already heated up over the decades. https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling It's not primarily about headroom.
bluGill 3y ago
Headroom is not an issue - there is plenty of room underneath the trains between the wheels. They then pump the cooled air up through the walls to where they want vents. Sometimes trains use the space between the wheels for passengers, but that has significant disadvantages and so should be avoided for subways (it is worth it for street running trams!),

thejsa 3y ago

Yes, given the size constraints of the deep-level Tube tunnels, which are much smaller than those for mainline trains; apparently developments in small air con systems have helped a fair bit here, fifteen odd years ago apparently it just wasn’t feasible.

anonymous_sorry 3y ago
Arguable the more fundamental problem is this. Air-con is a negative-sum game because it not 100% efficient. As well as moving heat from one place to another, it creates extra heat. Turn air-con on in an enclosed space, with nowhere to vent the exhaust, and that space just gets hotter. A small, deep tunnel is close to being an enclosed space. You might be able cool the train interior a bit, but the tunnel will get hotter. Meaning the air-con has to work harder. Meaning it generates more heat. The Picadilly line is already uncomfortably hot for a good part of the year (but far from the worst [1]). This includes the platforms. What this article says is that the trains themselves are lighter and more efficient, so less heat is generated by the motors and brakes. They argue that that gives them some heat budget to use on air-conditioning. As a whole, the new trains will generate roughly the same amount of heat as the old ones. So the tunnels and platforms will stay around the same (ie, too hot!), but the train interior will be comfortable. [1] https://www.standard.co.uk/news/london/tube-underground-london-temperature-hottest-b1103973.html https://www.standard.co.uk/news/london/tube-underground-lond...
- SideburnsOfDoom 3y ago
  Yes, "Where to vent the waste heat" is 100% the fundamental problem. You can't beat the second law of thermodynamics. The tunnels have absorbed heat over the decades, venting yet more heat into the tunnels is not going to work. More space would make the engineering easier, but it's not the fundamental issue.

londons_explore 3y ago

London underground runs in a parallel universe where they are reinventing 60's tech. They only recently got cell service for example. 20 years after most of the rest of the worlds railways. Some lines don't even have that yet either!

kmlx 3y ago
the london tube dates from 1863. that explains most issues.
walthamstow 3y ago
Of all the things TFL could do to improve the tube, cell service would not even be close to top of my list. We've had WiFi on the platforms for about 10 years which is enough to send/receive whatsapp messages while the train is stopped. I'm not sure it's fair to dig out TFL for being backwards. They introduced the Oyster in 2003, something NYC didn't get until 2019.
- londons_explore 3y ago
  Reliable comms everywhere allows fully centralized train control, with no employees on each train. You can use cameras to check no passengers are stuck in doors, on the track, or fighting in the carriages or platforms. Now you can redeploy the staff away from repetitive tasks of driving trains and supervising stations, and towards engineering a better service. Get the typical journey speed up from 12 mph up to 45 mph. Make one direction of all tracks an express route that only stops at one station in 10 and drives 60 mph through all the others. Modify the old tunnels with an extra rail on a wall or ceiling for places where the tunnel alignment can't do 60 mph.
  - walthamstow 3y ago
    Are you a railway engineer or in some other related field? Some of these suggestions sound a bit bizarre to a layman, especially considering your idea that the only thing standing in our way is 4G signal and reshuffling some staff. > Get the typical journey speed up from 12 mph up to 45 mph. So instead of 30 minutes from Walthamstow to Brixton it'll be 8 minutes? How is that possible? There are 16 stations, or 14 stops excluding the terminii. If you stop for 30secs at each, that's 7 minutes in itself. > Make one direction of all tracks an express route that only stops at one station in 10 and drives 60 mph through all the others So we would have an express lane in one direction and a stopping lane in the other? Why is that a good thing? To me an express service seems /slower/ than the status quo, because I would have to wait longer for the train that stops where I want it to.

bombcar 3y ago

Air conditioning a train in a tunnel is a trick, because the tunnels heat up and can’t dissipate heat well at all.

masklinn 3y ago

I don’t know if you’ve been to london, but if you’re a standard “modern” height for a man you can barely to not even stand straight in the deep tube trains. They are very very small, and limited by the tunnels which are absolutely tiny. I’m not surprised fitting air conditioning is a challenge, even ignoring the ventilation issues which are also massive.

kmlx 3y ago
a consequence of having the first subway in the world i think.
- sofixa 3y ago
  Yep, same as many other things we take for granted in modern constructions, such as accessibility, good signage, enough space on stations and tunnels for easy flow of passengers, platform screen doors, etc. It's a no brainer when building today, but wasn't back then, and retrofitting is extremely complex and expensive.
- rwmj 3y ago
  Dug "by hand": https://hornseyhistorical.org.uk/piccadilly-line-extension-part-two/ https://hornseyhistorical.org.uk/piccadilly-line-extension-p... https://en.wikipedia.org/wiki/Tunnelling_shield#Manual_shield_tunnelling https://en.wikipedia.org/wiki/Tunnelling_shield#Manual_shiel...
arethuza 3y ago
You should see the Glasgow Subway - its trains are almost comically small.
- jjgreen 3y ago
  The entire network is a single line which circles the city, the map shows 2 lines, one clockwise, one anticlockwise. The trains have a dirty orange livery, hence the local name: The Clockwork Orange. My favourite underground in the UK.

Nextgrid 3y ago

It's a huge achievement considering both the technical challenges (which other comments explain) but also that anything actually got done considering the UK's economic and political disaster.

kmlx 3y ago
> UK's economic and political disaster. i really don’t understand where this myth is coming from. do people seriously think the UK is an “economic disaster”? https://data.worldbank.org/?locations=DE-GB-FR https://data.worldbank.org/?locations=DE-GB-FR and here are the numbers for 2023: https://commonslibrary.parliament.uk/research-briefings/sn02784/ https://commonslibrary.parliament.uk/research-briefings/sn02...
- walthamstow 3y ago
  I don't think it's a myth. The UK is actually two economies. It's basically southern Italy with NYC bolted onto it. The average numbers like those you've posted include London and look basically OK, but the London effect is hiding a lot. Take out London and the rest of the UK is an economic basket case with low education levels, high rents, rapidly aging citizens, low wages, low investment, low productivity, a small tax base and a public estate in poor condition. This was a really interesting piece on the matter, in fact most of Murdoch's work for the FT is excellent https://www.ft.com/content/e5c741a7-befa-4d49-a819-f1b0510a9802 https://www.ft.com/content/e5c741a7-befa-4d49-a819-f1b0510a9... If you don't have a way to access the FT, this chart encapsulates my point quite well https://www.ft.com/__origami/service/image/v2/images/raw/ftcms%3A11abf22a-c668-4a1e-ab54-6801ce23db96?source=next-article&fit=scale-down&quality=highest&width=700&dpr=2 https://www.ft.com/__origami/service/image/v2/images/raw/ftc...
  - TheOtherHobbes 3y ago
    London itself is very divided. There's plenty of money in a few select areas, but wastelands of poverty around them. The UK has a huge reservoir of natural talent which it's doing its best to destroy. Plastic populism suits the ruling class much better than invention and originality.

bowsamic 3y ago

Here in Hamburg the S-Bahns are only just being replaced by air conditioned models. I don't think there are even plans for an air conditioned U-Bahn yet

anonymous_sorry 3y ago

It's best to read the article to understand why.

SideburnsOfDoom 3y ago

Where would the waste heat go? Air Conditioning units dump the heat "outside" into the air. But there is no "outside" in deep tunnels. Worse, Air Con has to work to move heat, which creates more heat. You can't even break even. See the 2nd law of Thermodynamics.(1) It's not so much "air con on trains" but "air con in deep tunnels without a vent". There is nowhere for the heat to go, and the tunnels have already warned up over the decades. (2) > Conventional air conditioning was initially ruled out on the deep lines because of the lack of space for equipment on trains and the problems of dispersing the waste heat these would generate. Every solution is a costly compromise. e.g. drilling a new vent to the surface is theoretically possible, but very hard in a densely populated and built-up area. A lot of comments talk about tunnel size, which is a minor factor: Everything's easier to engineer when you have more space. But fundamentally the issue is where to send the waste heat, not "tunnel too small". 1) https://en.wikipedia.org/wiki/Laws_of_thermodynamics https://en.wikipedia.org/wiki/Laws_of_thermodynamics 2) https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling

zeristor 3y ago
Couldn’t they make some spaces, and a drain and bring in large blocks of ice to take heat out? I’m guessing water would be creating more problems. But it’s a train line, bringing in large blocks of ice should be simple.

dwroberts 3y ago

The challenge here is specific to this line - other lines (like Circle) already have AC on the trains - mainly because they’re absolutely huge trains by comparison

rjmunro 3y ago
London 2 main types of underground line: Subsurface (Circle, District, Metropolitan and Hammersmith and City lines), and tube. The subsurface lines were constructed by cut and cover and were made for steam engines. They are much larger than the tube lines. The Tube lines are tunnelled, and designed for electric power only. It's not really the size of the trains that allows AC on the subsurface lines, it the fact that the lines are well ventilated to allow steam and smoke from steam engines to escape.
- dwroberts 3y ago
  Even the article specifically points out the size of the train as an issue > To fit air conditioning into the trains has been rather an interesting challenge, as air conditioning units are large and tube trains are small, and Siemens Mobility has taken several ideas and put them together to create the space needed.

Cthulhu_ 3y ago

It is here; they're small trains and the tunnels are very warm already, so the AC isn't as efficient, and adding more heat to the tunnels (which all comes from the running trains) will make it more inhospitable. There are some projects underway to try and cool the tunnels, but they're deep underground and have accumulated heat over decades.

DoughnutHole 3y ago

Air conditioning in a busy 19th century underground tunnel system is absolutely an achievement. Air conditioning an underground train means pumping that hot air into the tunnels. The tunnels have insufficient ventilation because this wasn't conceived of as a problem when many of them were built, and that's a challenge to rectify. There's also the issue that the trains are already making the tunnels too hot. 4000 trains running back and forth generates a lot of heat from both the engines and braking friction. That heat goes into the clay of the tunnel and is very slow to dissipate due to the high heat capacity of the clay. The trains are never stopped for long enough for the temperature to drop, and so the temperature of the clay has slowly risen 5-12 degrees depending on the line from when the first line was dug in 1863. Air conditioning the carriages of the new trains didn't result from any developments in air conditioning technology, but from breakthroughs reducing the thermal output of the engines and brakes. This gives them a heat "budget" letting them air condition the carriages without outputting any more heat into the tunnels than a standard train.

deleted 3y ago
[deleted]