4 ms·

Why doesn't London Underground use either slowed or stopped escalators when there are no passengers? I noticed in Berlin, escalators without people often run v

Why doesn't London Underground use either slowed or stopped escalators when there are no passengers? I noticed in Berlin, escalators without people often run very slowly. They speed up as soon as someone steps on. In Copenhagen, they stop. This is presumably more efficient, but it's easier to assume the escalator is broken, and a bit disorientating.

everfrustrated 4y ago
Where new escalators have been put in they do. Mostly this is in new stations or station entrances. Eg the new Cannon St Stn entrance. I suspect there's no reasonable way to retrofit them to existing ones - probably requires a different type of electric motor and AC speed controller plus sensors which is getting to be a pretty big job (so expensive even if the parts aren't). It takes TFL about 9 months to replace out an old escalator for a new one. I think I'm correct to say they have 50 year operational lives.
- ajsnigrutin 4y ago
  > It takes TFL about 9 months to replace out an old escalator for a new one. I think I'm correct to say they have 50 year operational lives. Seriously? Why? Genuinely curious It takes them a few days to replace the ones in local supermarkets, including the flat conveyor ones to carry the trolleys.
  - Symbiote 4y ago
    Probably because they're bespoke, subject to heavier use, located in confined spaces, and are expected to run 20 hours a day for 50 years.
  - Delphiza 4y ago
    The health and safety aspect is mind-numbingly overbearing. And for good reason. It is an underground workspace that is surrounded by the general public. When escalators are replaced the entire work area gets boxed in. There must be significant controls in terms of dust, gas (like welding equipment), noise etc. Fire is a significant risk and the underground has history that makes them anxious about fire and escalators (see Kings Cross Fire). Most of the work probably has to take place after hours, and subject to other maintenance taking place. On the underground, you can't just put a new escalator in a docker container and spin it up. The Underground is a significantly complex environment.
  - brk 4y ago
    From a few cases I have seen, it is partly due to the very long service life. New units are substantially different from older ones, particularly in all the bits of it that you do not see as a pedestrian. Often times the retrofit involves a lot of concrete work and other work to adapt the mounting and support points to accommodate the newer designs. Couple this with the fact that you are usually doing the work in sub-optimal conditions because they are trying to keep the rest of the area open for pedestrians, so there is additional safety considerations that you don't have in a new construction install.
  - PebblesRox 4y ago
    Reminds me of this interesting behind-the-scenes look at an escalator replacement: https://news.ycombinator.com/item?id=28207386 https://news.ycombinator.com/item?id=28207386
lozenge 4y ago
I'm not sure any of them would turn off for longer than 2-3 minutes at a time. The minimum frequency would be about 12 tph (5 mins interval) but that's in each direction. You only need one person alighting from a train to cause the elevator to turn on. The less used suburban stations don't have escalators at all.
zarzavat 4y ago
Some of the escalators on the Underground are terrifyingly deep. They could do variable speed for some of the shorter ones, but implementing that for the long escalators would cause more than a few accidents.
- samhw 4y ago
  Yeah, I'm not sure non-Londoners appreciate this. The escalators at Angel (where I grew up) go 60m deep. Someone skiied down them and hit 30mph: https://en.wikipedia.org/wiki/Angel_tube_station#Escalator_skiing_incident https://en.wikipedia.org/wiki/Angel_tube_station#Escalator_s... https://youtu.be/rlF4nRUbKmc?t=53 https://youtu.be/rlF4nRUbKmc?t=53.
  - DoughnutHole 4y ago
    This is something I noticed experiencing undergrounds in Germany after previously only experiencing them in London - London's escalators are insane, the Cologne U-Bahn is practically surface level by comparison. If I were to hazard a guess this is because of the soft clay that London is built on - on the one hand the soft material makes it very easy to dig tunnels, on the other hand if those tunnels are dug too shallow they will very easily destabilise the foundations of the buildings above. So you have to to build them at a depth which would be prohibitively expensive somewhere built on harder rock.
    - deleted 4y ago
      [deleted]
    - wikfwikf 4y ago
      Some tube lines are very deep but there are also several which are cut-and-cover, ie at the same just-below-street depth as the NY subway.
    - andylynch 4y ago
      Not only that, as Crossrail demonstrated one must also avoid the numerous existing tunnels (not just trains, but also utilities and even rivers). Not all of which are precisely mapped or even know about! Even then, the gap between tunnels in some stations is on the order of centimetres
dan-robertson 4y ago
I think part of the reason is just that they aren’t frequently replaced (I think it is often a very annoying place to install new escalators). Personally I prefer to manually climb the stairs and I’m often surprised by how much space there is between escalators (it often seems like 50% of the width of a tunnel is just metal closing up the space between the parts of the escalators you can stand on) but I think my opinion is rare and it would be inefficient to have a flight of stairs that nearly nobody uses.

everfrustrated 4y ago

Where new escalators have been put in they do. Mostly this is in new stations or station entrances. Eg the new Cannon St Stn entrance. I suspect there's no reasonable way to retrofit them to existing ones - probably requires a different type of electric motor and AC speed controller plus sensors which is getting to be a pretty big job (so expensive even if the parts aren't). It takes TFL about 9 months to replace out an old escalator for a new one. I think I'm correct to say they have 50 year operational lives.

ajsnigrutin 4y ago
> It takes TFL about 9 months to replace out an old escalator for a new one. I think I'm correct to say they have 50 year operational lives. Seriously? Why? Genuinely curious It takes them a few days to replace the ones in local supermarkets, including the flat conveyor ones to carry the trolleys.
- Symbiote 4y ago
  Probably because they're bespoke, subject to heavier use, located in confined spaces, and are expected to run 20 hours a day for 50 years.
- Delphiza 4y ago
  The health and safety aspect is mind-numbingly overbearing. And for good reason. It is an underground workspace that is surrounded by the general public. When escalators are replaced the entire work area gets boxed in. There must be significant controls in terms of dust, gas (like welding equipment), noise etc. Fire is a significant risk and the underground has history that makes them anxious about fire and escalators (see Kings Cross Fire). Most of the work probably has to take place after hours, and subject to other maintenance taking place. On the underground, you can't just put a new escalator in a docker container and spin it up. The Underground is a significantly complex environment.
- brk 4y ago
  From a few cases I have seen, it is partly due to the very long service life. New units are substantially different from older ones, particularly in all the bits of it that you do not see as a pedestrian. Often times the retrofit involves a lot of concrete work and other work to adapt the mounting and support points to accommodate the newer designs. Couple this with the fact that you are usually doing the work in sub-optimal conditions because they are trying to keep the rest of the area open for pedestrians, so there is additional safety considerations that you don't have in a new construction install.
- PebblesRox 4y ago
  Reminds me of this interesting behind-the-scenes look at an escalator replacement: https://news.ycombinator.com/item?id=28207386 https://news.ycombinator.com/item?id=28207386

lozenge 4y ago

I'm not sure any of them would turn off for longer than 2-3 minutes at a time. The minimum frequency would be about 12 tph (5 mins interval) but that's in each direction. You only need one person alighting from a train to cause the elevator to turn on. The less used suburban stations don't have escalators at all.

zarzavat 4y ago

Some of the escalators on the Underground are terrifyingly deep. They could do variable speed for some of the shorter ones, but implementing that for the long escalators would cause more than a few accidents.

samhw 4y ago
Yeah, I'm not sure non-Londoners appreciate this. The escalators at Angel (where I grew up) go 60m deep. Someone skiied down them and hit 30mph: https://en.wikipedia.org/wiki/Angel_tube_station#Escalator_skiing_incident https://en.wikipedia.org/wiki/Angel_tube_station#Escalator_s... https://youtu.be/rlF4nRUbKmc?t=53 https://youtu.be/rlF4nRUbKmc?t=53.
- DoughnutHole 4y ago
  This is something I noticed experiencing undergrounds in Germany after previously only experiencing them in London - London's escalators are insane, the Cologne U-Bahn is practically surface level by comparison. If I were to hazard a guess this is because of the soft clay that London is built on - on the one hand the soft material makes it very easy to dig tunnels, on the other hand if those tunnels are dug too shallow they will very easily destabilise the foundations of the buildings above. So you have to to build them at a depth which would be prohibitively expensive somewhere built on harder rock.
  - deleted 4y ago
    [deleted]
  - wikfwikf 4y ago
    Some tube lines are very deep but there are also several which are cut-and-cover, ie at the same just-below-street depth as the NY subway.
  - andylynch 4y ago
    Not only that, as Crossrail demonstrated one must also avoid the numerous existing tunnels (not just trains, but also utilities and even rivers). Not all of which are precisely mapped or even know about! Even then, the gap between tunnels in some stations is on the order of centimetres

dan-robertson 4y ago

I think part of the reason is just that they aren’t frequently replaced (I think it is often a very annoying place to install new escalators). Personally I prefer to manually climb the stairs and I’m often surprised by how much space there is between escalators (it often seems like 50% of the width of a tunnel is just metal closing up the space between the parts of the escalators you can stand on) but I think my opinion is rare and it would be inefficient to have a flight of stairs that nearly nobody uses.