[HN Gopher] South Kensington station's escalator replacement pro...
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South Kensington station's escalator replacement project
Author : edward
Score : 226 points
Date : 2021-08-17 08:07 UTC (14 hours ago)
(HTM) web link (www.ianvisits.co.uk)
(TXT) w3m dump (www.ianvisits.co.uk)
| barneybooroo wrote:
| It is amazing how what might seem like fairly routine engineering
| jobs become completely nightmarish once you do it underground.
|
| I used to commute via Goodge Street every day. A few years ago
| they replaced the four lifts (in twos so that two were still in
| service) which ultimately took two years. I could never really
| fathom what it was that specifically slowed that down so much but
| hey the lift congestion every morning was fun
| ddek wrote:
| Compound that with the depth work too.
|
| Unlike most metro systems, many London Underground (tube) lines
| are bored, and at a much greater depth. The Northern, Victoria,
| Bakerloo and Jubilee lines go under the river; while most
| systems route trains over bridges.
|
| The history of the tube is fascinating. The most recent lines
| (Victoria, Jubilee, CrossRail/Elizabeth) were built by a
| centralised authority. The older lines were built by various
| railway companies wanting to extend their lines into London.
| Over the years, railway companies dissolved and merged, leaving
| the fairly awkward map (the two branches of the Northern line
| share a platform at Camden, a stations at Euston and
| Kennington, and usually nothing else).
|
| Because of the depth and lack of foresight when building
| anything, changing the network is nigh on impossible without
| major disruption.
|
| For example, a new terminal is being built at Bank, meaning the
| Northern Line platform is no longer a 'bridge' between Bank and
| Monument. Most of the work is done, but a substantial amount of
| the line will close for 3 months to finish it off.
| (Unfortunately, this is my commute. It's annoying but I'm ok
| with it.)
| ljm wrote:
| It's like Passeig de Gracia in Barcelona, going from the
| green line down to the more central yellow and purple lines.
|
| It's sometimes quicker, or at least nicer, to walk above
| ground than it is to take the gigantic tunnel (spanning maybe
| 3 blocks) between the two.
| asdff wrote:
| As dramatic as line closures are, the impact to commuters can
| be minimized if the transit agency supplies shuttlebusses
| servicing the line in its place. When LA metro closed
| substantial sections of the Expo and Blue lines a few years
| ago, the shuttle routing only added a few extra minutes to
| commuters trips along those corridors.
| ddek wrote:
| Nice idea, but no chance it works in London. It's faster
| for me to go the long way round the northern than anything
| overground, even a taxi.
| andrewaylett wrote:
| Unfortunately, that's unlikely to work in London where
| there are already more people on public transport than
| private transport [0]. The London Underground has roughly
| twice the overall capacity of the London Bus network [1].
|
| [0]: Specifically inner London, ref Page 67 of
| https://content.tfl.gov.uk/travel-in-london-report-13.pdf
|
| [1]: By spaces-times-distance, ref Page 101 ibid.
| gsnedders wrote:
| You need 187 buses per hour to have the same capacity as
| the Piccadilly Line has on-peak (using the capacity of the
| New Routemaster), or, alternatively, three buses per
| minute. It's hard to imagine any way in which that is
| practically workable. I think the most frequent bus service
| in London currently is scheduled for 30 buses per hour, by
| way of comparison.
|
| Add to this the fact that average road speed in Central
| London is about a third of average Underground speed, hence
| you're quite possibly looking at making journeys three
| times as long, even ignoring the extra congestion that all
| those buses would cause.
| jaclaz wrote:
| From experience in construction (both open air and underground)
| the key difference is not about something being underground,
| but rather with something being "in use" _while_ the building
| site is doing the _whatever_ work is needed.
|
| Particularly when it is something of public use, be it a
| highway or a railway, the amount of precautions, limitations
| and safety risks (in some cases for both the public and the
| workers) grows incredibly, slowing down considerably _any_
| intervention.
| bartread wrote:
| This happens in software too.
|
| Over the last 4 years our team has achieved a lot: huge
| numbers of valuable changes and improvements to our platform.
| But it's been much harder than it might otherwise have been
| because we've had to make those changes with the systems in
| use. Had we started from scratch, or been able to take
| downtime, there are a lot of projects we could have done much
| more quickly, but we _had_ to keep the business running - it
| is, after all, what was and is paying all of our salaries.
| tomfanning wrote:
| Isn't this completely standard practice now?
| bartread wrote:
| Not always. I've worked on all sorts with different
| companies.
| tialaramex wrote:
| 24/7 is table stakes for many Internet companies, but
| lots of outfits which _think_ of themselves as delivering
| that sort of service actually cheerfully carve out hours
| or even days of down time as "necessary".
|
| One of my banks decided it was going to do a "major
| upgrade" one weekend. Advertised I think maybe 8 hours
| outage like hey, who needs a _bank_ for eight hours
| right? And of course their team can 't actually hit that
| schedule, but nobody wants to choose "Roll back, fall on
| my sword at breakfast time" so an hour _after_ the end of
| that supposed 8 hour outage their telephone support were
| telling me it ought to be fixed "soon" and any problems
| are only "temporary" and I can try again in a few
| minutes.
|
| They got it back later that day, no noticeable
| improvements and you can bet that even if there was some
| enquiry about what went wrong nobody learned anything
| from it. Like NASA after Challenger. And they will still
| send representatives to the IETF who will say well, we
| can't afford these random outages like you Internet
| people, we're a _bank_ , we need high availability. And
| those representatives will look around wondering why
| everybody is laughing.
| [deleted]
| ljm wrote:
| I like taking the stairs at those stations. I think Russell
| Square is the station with a particularly long staircase; 200
| or more steps.
|
| If you like epic spiral staircases you can't go wrong in
| London.
| lbriner wrote:
| Underground does present challenges but there are many reasons
| why these seemingly straight-forward jobs take time. You need
| qualified/certified workers, a load of up-front work related to
| ventilation, noise, structural movement, surveys etc. Some of
| this can only be done in engineering hours.
|
| You have issues around the lack of space in central london for
| work vehicles, the need for removal of rubbish which can't
| block up emergency staircases, exits.
|
| Then add in the challenges of unknown unknowns and needing to
| be able to revert any change quickly that can't be done to plan
| so you don't end up with a closed station and you start to get
| there.
|
| I assume they had to do them 1 at a time to completion as well?
| csours wrote:
| I wonder what Mitch Hedberg would have to say about this:
|
| https://www.youtube.com/watch?v=7n1ryH3igKc
|
| Unfortunately, escalators can break catastrophically - See these
| comments in this thread:
| https://news.ycombinator.com/item?id=28208925
| FabHK wrote:
| The article didn't mention the length of the escalator?
|
| Longest ones apparently are to be found at the Park Pobedy metro
| station in Moscow at 126 m, and in St Petersburg.
|
| Longest escalator system, and my favourite, is the Hong Kong
| Central-Mid-Levels escalator, at 790 m (2,600 ft). Many people's
| commute to work.
|
| https://en.wikipedia.org/wiki/Central-Mid-Levels_escalator
|
| Escalator accidents:
|
| 1982 Moscow
| https://en.wikipedia.org/wiki/Aviamotornaya_(Kalininsko-Soln...
|
| 2018 Rome https://www.theguardian.com/world/2018/oct/23/hurt-in-
| rome-m...
| asdff wrote:
| The Wilshire Vermont metro station in Los Angeles has the
| longest escalator west of the mississippi river. It's so long
| that its much faster actually to take the elevator from that
| platform, if you can out run people from the train to the
| single elevator that is. The escalator system at Universal
| Studios Hollywood is also pretty impressive.
| coremoff wrote:
| the 1987 King's Cross fire was also escalator related:
| https://en.wikipedia.org/wiki/King%27s_Cross_fire
|
| Smoking on the escalators, wooden steps, and build-up of trash
| in the inaccessible area underneath them all contributed.
| seryoiupfurds wrote:
| > This sudden transition in intensity, and the spout of fire,
| was due to the previously unknown trench effect, discovered
| by the computer simulation of the fire, and confirmed in two
| scale model tests.
|
| https://en.wikipedia.org/wiki/Trench_effect
| walshemj wrote:
| I just missed that fire as I left early that day to get back
| home for a DnD game.
|
| My normal commute would have taken me right into the center
| of the fire.
| lbriner wrote:
| If you want a really interesting read, which is great at
| showing how a methodical enquiry is carried out is here: http
| s://www.theisrm.org/documents/Fennel%20(1988)%20Investig...
|
| It might look long but is still really interesting to read,
| the simple questions that needed to be answered, the
| interviews and the conclusion.
| gsnedders wrote:
| IIRC, they're not particularly long. The deep level tunnels are
| something like 20m below the subsurface tunnels, I'd guess 30m
| in total from the ticket hall?
| knolan wrote:
| This was my daily commute back when I was a post doc at Imperial
| College. Good memories of London.
| piinbinary wrote:
| It's really cool that they can use the train tracks to bring
| stuff into and out of the station. It seems obvious in
| retrospect, but that had never occurred to me before.
| blamazon wrote:
| In New York City there is currently a project ongoing deep
| underneath Grand Central Terminal to add an entirely new
| 8-track, 350,000sqft station connecting Grand Central to the
| Long Island Railroad.
|
| Similarly, all materials for that project enter and exit from
| the other end of the project tunnel in Queens. New York City at
| ground level has no indication that the work is ongoing 140
| feet below their... well, feet. Very neat!
| elahd wrote:
| This isn't just a construction phenomenon. The NYC MTA uses
| trains for collecting garbage and, until recently, money.
|
| https://www.nydailynews.com/new-york/mta-refuse-rigs-collect...
|
| https://en.wikipedia.org/wiki/Money_train
| Symbiote wrote:
| If you use the London Underground late enough, you occasionally
| see engineering trains pass through.
|
| I think they move them to sidings in central London very late
| in the evening, so that after the last passenger train has
| departed (00:30-01:00) the equipment/materials can be where
| they're needed in just a few minutes.
|
| [1]
| https://en.wikipedia.org/wiki/London_Underground_engineering...
|
| [2] A web search for "London Underground engineering train".
|
| [3] http://cartometro.com/cartes/metro-tram-london/ (detailed
| map, showing sidings etc)
| _jal wrote:
| Speaking of special-purpose trains, the NYC MTA used to run
| an armored train for collecting fares from stations.
|
| https://untappedcities.com/2016/02/12/the-mtas-special-
| armor...
| frosted-flakes wrote:
| Lots of systems did that, including Toronto, and for daily
| trash collection too. But logistically it's simpler to do
| that via surface streets nowadays, especially with late-
| night or all-night train service.
| lbriner wrote:
| It's not that "obvious" and is not always used. For a start,
| the power is often off at night so you need one of the few
| battery locos. You also need a clear route from the station to
| the nearest loading/offloading point, which might be several
| mile away from the station.
|
| A lot of time, materials and tools are simply loaded through
| the station manually and since you are not allowed to store
| anything flammable below ground, some of it needs to be taken
| back out at the end of the shift.
|
| They are not keen to lose station time but sometimes I think
| they could afford to lose an hour either end when they are
| doing engineering work in a station. At least in this instance,
| they needed to close the station which saves so much time.
| bloqs wrote:
| I havent read the full article, but why is this the number 2
| story on HN? Have I sorted incorrectly?
| teh_klev wrote:
| > but why is this the number 2 story on HN?
|
| Because it's interesting to a lot of folks.
| matkoniecz wrote:
| Because it is
|
| (1) interesting
|
| (2) new to nearly all
|
| (3) something that people want more on HN
|
| (4) on topic here
| iamhamm wrote:
| I can't tell you why this is the #2 story, but fortunately your
| comment is dead last so I've got some evidence the ranking
| algorithms are working appropriately.
| fortran77 wrote:
| I've never known a hacker who didn't like trains and
| escalators.
| swiley wrote:
| Because transit infrastructure is really neat.
| lbriner wrote:
| Because older articles lose karma and drop down the list. Not
| many new highly voted articles for today yet.
| lbriner wrote:
| This is a great example of why underground railways are so
| expensive to run. I don't believe the London Underground has ever
| been profitable.
|
| Not only is it expensive to install equipment, you then have to
| maintain it and replace it and in this example, not even "like
| for like" are going to fit in the same space.
|
| When I used to go round various equipment rooms, there was
| electrical equipment that was the best part of 100 years old. Who
| would ever remove it in case it is wired into the signalling
| system or whatever? For that reason, they have to wait and then
| do a massive re-signalling etc. so they can safely remove
| everything and put nice expensive new stuff in!
| helloguillecl wrote:
| I don't get why so many people and politicians speak about
| profitability as if it was an optional system for a modern city
| to have.
|
| Yes, the income via transportation fees are usually similar to
| operating expenses, but like it's the case with roads, no one
| should expect for it to cover the full cost of building the
| infraestructure, much like roads.
|
| The tube is not a part of a closed system and delivers
| thousands of other societal and economic benefits that are not
| reflected in the fees paid by their direct users.
|
| Also, this infraestructure can last for more than one century,
| as I understand is the case of London's tube.
| lbriner wrote:
| I don't think it is as much about profitability but more like
| who should pay for it. In one world view, the people who use
| it should pay for it, whatever that costs, in the ticket
| price. This gives direct pressure to keep costs down.
|
| Another view is that it mostly benefits people in London so
| it should come out of London's Council tax (which I think
| part of it does).
|
| The other view is that it is a general benefit to society and
| can and should be bankrolled by government. Then the problem
| is that the pressure to keep costs down is perhaps political
| and it is hard to know how much subsidy is fair.
| Symbiote wrote:
| TfL is funded from fares, the congestion charge, business
| rates and grants from the Greater London Authority -- which
| itself is funded by the national government and some
| council tax.
|
| https://tfl.gov.uk/corporate/about-tfl/how-we-work/how-we-
| ar...
|
| (Note TfL are also paying for buses, trams and many larger
| roads in London.)
| willyt wrote:
| It mostly transports people who live in the 'home counties'
| (the smaller towns and countryside surrounding London) to
| and from the major rail stations, so maybe they should pay
| for it. e.g. 750,000 people pass through King Cross station
| in the morning rush hour.
| asdff wrote:
| At the same time there are benefits to nontransit users
| having a chunk of the population use transit. The roads
| are clearer, for one. Less smog, for two. Higher national
| GDP due to less resources overall required to move labor
| from housing to the means of production, for three. I'm
| sure there are more reasons, too.
| noneeeed wrote:
| On the railways in general there is a strong inclination
| towards keeping what works as the potential downsides of
| getting it wrong can be literally catastrophic. Things like
| solid-state interlocks, are reliable and trusted; it's taken a
| lot of work to develop the same kind of trust in software based
| systems.
|
| I worked in railway safety back in the early 2000s and moving
| block signalling was like nuclear fusion, the great hope for
| increasing capacity and always just around the corner. While
| it's in use on some underground lines, it still isn't in
| widespread use on surface lines, it's just proved really hard
| to get right. We are getting there, it will form part of future
| systems in Europe, but it's taken decades to get to the level
| of maturity where people will trust it to carry thousands of
| people at intercity speeds through complex rail networks.
| bregma wrote:
| > I don't believe the London Underground has ever been
| profitable.
|
| The subsurface lines were profitable for at least their first
| 50 years. Oddly, their profitability started to tumble at about
| the same time as the rise of the automobile, reinforced by the
| foreign-based urban renewal blitz that occurred a couple of
| decades later in which many homes and places of employment were
| forced to relocate.
| matkoniecz wrote:
| > profitable
|
| Infrastructure like roads is rarely directly profitable.
| sschueller wrote:
| You have to maintain and replace all infrastructure eventually.
| Maintenance should be part of the project calculation and how
| items are maintained should also be part of that. Additionally
| how things are maintained needs to be updated to go with new
| technologies and methods.
|
| I see this with for example the public transport in Zurich,
| Switzerland. Some of the light rail is very old but they are
| maintenance revisions done on them and things are continuously
| improved or replaced. Same goes for the tracks which have to be
| pulled out of the streets every few years and replaced. How
| this is done has improved tremendously over the years and
| materials of the track have also changed.
|
| Another example are the electric busses that used to have a
| gasoline backup generator. These have now all been replaced
| with batteries as they became small and efficient enough to
| replace the generator.
|
| Letting the bus run until it's dead will end up costing more
| than keeping it in good working condition.
| lbriner wrote:
| Great in theory but if you are managing a system now, you
| would rather spend money on things you need now, you aren't
| going to keep it in the bank for some future day when the
| escalator needs replacing.
|
| I suspect that equipment is depreciated in TfL accounts but
| the people 50 years ago wouldn't know how much this
| replacement would have cost so who knows.
| sschueller wrote:
| The trains will run for 100+ years. This is possible
| because almost all parts can be made in house and those
| that can't are eventually replaced.
|
| I'm fact the Zurich rail company (ZVV) in their purchase
| deal of the bombadier light rail included all plans for all
| parts. Bombadier was not happy but the ZVV has to make sure
| they can service the trains even if the manufacturer goes
| away.
|
| This is also the reason LED lighting it a very delayed roll
| out in the city because the city can not use a light that
| is vendor locked which most commercial LED setups are. The
| old Natrium lighting can be purchased anywhere from. many
| different vendors. The fitting is standardized.
| simpleigh wrote:
| That's not right, I'm afraid - the Underground is usually
| profitable and subsidises loss-making forms of transport
| (particularly buses). Here's some high-level, pre-pandemic
| figures: https://diamondgeezer.blogspot.com/2018/03/average-
| yield-and...
|
| (based on TfL's draft budget for 2018-19)
| 7952 wrote:
| There is so much pent up demand for transport in the UK that
| it completely distorts things. You can have a system that is
| overcrowded, profit making, expensive for users, and
| underfunded all at the same time. The economic pulls that
| could fix this are outweighed by things like housing costs.
| hogFeast wrote:
| The govt bailed them out last year.
| Milner08 wrote:
| Right, cause covid. You know, when no one was using the
| service but they had to keep operating for front line
| workers... hard to make money when there are no users.
| hogFeast wrote:
| So they were profitable...discounting all the times they
| lost money.
| cryvate1284 wrote:
| The comment you are replying to said "usually" and that was
| in response to the GP that said "I don't believe the London
| Underground has ever been profitable."
|
| The government did not bail out the London Underground in
| particular last year but TfL, though I would be surprised
| if the underground was profitable last year.
|
| Anyway, unsure what your comment was adding.
| noneeeed wrote:
| Fascinating post as always from Ian.
|
| My dad used to work for the underground and hearing him talk
| about the challenges of the engineering down there was always
| fascinating. This is especially true for the deep tunnels and the
| older parts of the network. Trying to keep the whole network dry,
| when you are dealing with brickwork that might be 100 or more
| years old, in a water table that has risen a lot following the
| end of heavy industry in London sounded like a particularly
| tricky issue.
|
| Add in the constrained space and often very limited access on the
| deep lines and you can understand why it can take so long to do
| some projects, and why things like longer operating hours might
| sound nice but have significant knock-on effects.
| [deleted]
| m4rtink wrote:
| How did the heavy industry influence the water table ?
|
| I guess they used a lot of water from wells, lowering the water
| table ?
| noneeeed wrote:
| Yep, basically. Water use is one of those hidden effects of a
| lot of industrial processes, whether it's used as a coolant
| or a solvant for processes it often takes a ridiculous amount
| to produce many goods.
|
| In the past the water would be pumped up from boreholes
| (London sits on an artesian basin), and was then discharged
| into the Thames (directly or through the waste water system).
| This happens a lot less now, because of both a reduction in
| the amount of industry and improvements in efficiency, so the
| water table has risen, which means that TfL have to pump out
| a lot more water than they had to decades ago.
| scoopr wrote:
| > Down here, there's no space for heavy machinery, so all the
| rubble had to be shifted by hand
|
| I wonder, if the engineering train couldn't fit a small loader,
| something like Avant (perhaps E6 for being electric for confined
| spaces), though I'm sure there exist some smaller ones too.
|
| Or maybe engineering train could be fitted with a HIAB style
| thing..
| Ichthypresbyter wrote:
| I remember hearing that the very long walk between South
| Kensington station and the Exhibition Road exit (for the museums)
| is because the line was routed far away from Exhibition Road to
| avoid vibrations from the trains disturbing sensitive experiments
| at Imperial College.
| traceroute66 wrote:
| To be honest, for me the most interesting part of the blog post
| was this one-liner "for an unbuilt high-speed District line
| service between South Kensington and Mansion House with just one
| stop at Embankment.".
|
| As one of the millions who at some historical point in their
| lives has had to suffer the District line commute, the above is a
| thought I used to have regularly whilst stuck sniffing someone's
| armpit on the District line ... why can't they have non-stop
| services intermingled with normal traffic (just like in any other
| number of countries around the world).
|
| They could have used the same rails, no need for a separate line
| (just like other countries around the world)... its a shame
| London Underground seemingly only considered the most expensive
| option (building separate tracks and tunnels for the non-stop).
| dspillett wrote:
| For large parts of London's underground (and overground[+]) it
| is simply the case that it wasn't really designed -- lines were
| slapped in willy-nilly by disparate commercial interests with
| relatively little forward planning, and only later became
| something like a coherent whole with some consideration for
| coordinated thinking. Once the lines are in, upgrading them is
| more difficult than building them in the first place,
| particularly if you don't want to stop service for large parts
| of the improvement work.
|
| _> just like in any other number of countries around the
| world_
|
| Other cities had extra benefit of hindsight, being able to
| design around the problems identified in older systems
| (particularly London's).
|
| _> They could have used the same rails, no need for a separate
| line
|
| You at least need passing places around stations in practise.
| In _theory* you could have many extra points and pass trains
| between the existing two lines to work around each other
| instead of keeping one line dedicated for each direction (as is
| the case for most of the track length) even at stopping points
| like stations _but_ that gets complex to manage, has more
| moving parts (which are difficult to maintain in the confined
| space), would considerably slow down flow at busy periods as
| the trains can 't move as fast over the points (particularly if
| they may need to switch line at them) and will spend time
| waiting for an opposing train ahead to switch out of the way,
| the tunnel around each change point needs to be wider (for the
| train partly, unless you redesign them too, for maintenance
| even more so), ... It might work for a small number of non-stop
| trains worming their way through the system around the majority
| stop-start services, but that number of services would be so
| small to the point where the investment would not be nearly
| worth the small overall gain in reduced journey times.
|
| [+] only about 45% of the line distance of the current tube is
| actually underground[++] [++] though that includes large
| overground sections in the outer zones if you are only
| considering central London I suspected that %age is
| considerably higher
| traceroute66 wrote:
| Thanks for the insight @dspillett, makes sense.
| brainwad wrote:
| Express services on shared track isn't common on metro systems.
| NYC's express subways all use dedicated track, for instance.
| The tendency to not keep to a strict timetable and the close-
| running of metro systems makes it hard to slot express trains
| into gaps between local trains properly.
| traceroute66 wrote:
| > The tendency to not keep to a strict timetable and the
| close-running of metro systems makes it hard to slot express
| trains into gaps between local trains properly.
|
| To be fair, "close-running" is not a word that tends to be
| associated with the District line ... "signal failure" is,
| however ! ;-)
| Symbiote wrote:
| The central section (including the Circle Line) has a
| service interval of 2-21/2 minutes, depending on the time
| of day.
|
| The rest has roughly 2-10 minute intervals.
| zhte415 wrote:
| Trivia. The timetable, or Working Table, for all London
| Underground train movements is here
| https://tfl.gov.uk/corporate/publications-and-
| reports/workin...
| nicoburns wrote:
| Crazy that the time between trains is measured in seconds
| marcinzm wrote:
| Even with a strict timetable you need extra spacing between
| trains and potentially slowdowns to allow passing to be done
| properly. These systems on busy lines tend to run trains as
| close to each other as possible without causing safety issues
| so there's no buffer room. And if something goes wrong for
| any reason the whole system starts getting cascading delays.
| lbriner wrote:
| There are not many/any high-frequency metro systems that can do
| this on the same rails. At peak times, when you could do with
| the expresses the most, there can be stopping services 1/2
| minutes apart on average, which means non-stoppers are simply
| not possible.
|
| On regional railways, where the service might be every 30
| minutes or longer, it is a different prospect since you can
| send the stopper out immediately after the express and it gets
| 30 miuntes to get out of the way.
| s15624 wrote:
| The majority of the tube network is pretty much already at peak
| capacity, with trains on the Victoria, Jubilee and Northern
| being full autonomous with moving block systems as separation
| distance can now only be maintained through autonomous systems.
| I think an express service would be wonderful but it would
| require careful orchestration.
|
| I think it might be worth increasing the line speed through
| signaling upgrades and more automation.
| nicoburns wrote:
| They are effectively building an express system as seperate
| lines. E.g. the new Elizabeth line is effectively an express
| Central line.
| traceroute66 wrote:
| Isn't the problem with automation on the tube less the
| technology but more the unions ?
| lbriner wrote:
| It is mainly due to an enormous expense and wanting to keep
| everything running during upgrades.
|
| If you are already costing the taxpayer X million per year
| and then you want another 400M for an upgrade, are you
| likely to get it?
| gsnedders wrote:
| Full automation--without drivers--would typically require
| platform edge doors, which are expensive and troublesome to
| introduce without disrupting service, and very difficult on
| some of the curved platforms.
|
| The benefit for the cost involved really just isn't there;
| while drivers aren't cheap they aren't impossibly expensive
| in comparison with the average number of passengers per
| train.
| lmm wrote:
| No, it's the technology or perhaps the companies supplying
| it (unions are only ever a problem in the US - or maybe
| they're never a problem and there's only a propaganda
| system against them in the US). London Underground are
| currently in the process of literally the third attempt to
| upgrade the signalling on the subsurface lines (i.e.
| including the District) - the previous attempt by
| Bombardier failed outright (as London Underground were
| aware it would from the early days, but they were
| politically obliged to wait until the company admitted as
| much), and the one before that (a similar story with New
| Labour ideology-driven PPP) was also abandoned.
| noneeeed wrote:
| The only way to have express and stopping trains on the same
| track is to have frequent passing places. Scheduling and
| signalling get fiendishly complex. On somewhere like the
| underground, where building those extra passing places is
| _really_ hard it just isn 't worth it.
|
| This is one of the big missunderstandings about the HS2 line.
| Politicians focus on the shorter journey times, but the big win
| is actually increased capacity. HS2 will take the express
| trains off the normal line. With just HS trains on that line
| you can run more of them than you can if you have stopping
| trains sharing the track. In addition you should actually be
| able to run more stopping trains faster since they don't need
| to be fitted in around the expresses with no extended stops
| waiting for a delayed express to pass at a station or passing
| place.
| gpvos wrote:
| Re HS2: I am familiar with the capacity-and-speed-difference
| argument, but I recently found out[0] that the WCML, MML and
| ECML are all already four-tracked, so you already _have_
| separation of fast and slow trains. Is further separation
| really still worth it?
|
| [0] I don't live in the UK, so I didn't know that yet despite
| being a railway nerd.
| willyt wrote:
| Freight 60-80mph constant speed. Stopping and semi-fast
| passenger up to 100mph but varies a lot. Fast passenger
| between 125-140mph. Fast-passenger is moving to HS2 albeit
| at 10 times the cost it would be to do the same thing in
| France.
| gpvos wrote:
| (For easier reading and understanding: freight 100-130
| km/h, stopping/semi-fast up to 160 km/h, fast 200-225
| km/h.)
| Symbiote wrote:
| The WCML has to accommodate very long distance express
| trains, regional trains, suburban/commuter trains, and
| freight.
|
| I think you can read section 2 of [1], and the start of
| section 3. With enough trains, you can still fill up a
| four-track railway.
|
| [1] https://assets.publishing.service.gov.uk/government/upl
| oads/...
| adwww wrote:
| Could you have odd / even trains that miss stops?
| lbriner wrote:
| This creates a very significant passenger challenge. How do
| the customers know which train to get on and what if they
| get on the even stop and need to get off an odd stop? They
| have to change train. If they can't pass each other then
| they don't save much time.
|
| In NY, the expresses are easier to understand because the
| rules are very simple.
| asdff wrote:
| They used to do it in Chicago for a long time. Trains and
| stops are labelled A or B and some stops would be
| labelled AB if evens and odds both stopped.
| noneeeed wrote:
| Yes, you can do things like that, but that ends up with you
| having two different sets of stations that are not easy to
| get between. The normal pattern is express trains that stop
| a few times with stoppers that "fill-in" between, but there
| will be different patterns of stopping to try and optimise
| for different groups of travelers.
|
| Scheduling/timetabling is a wickedly hard problem,
| especially in a system like a railway, it's the sort of
| thing people get Maths and CS PhDs in. The contstraints
| that you have to solve are complex and interconnected and
| are part of a bigger network, and you are also trying to
| please a lot of people with very different (often
| contradictory) needs.
| jfindley wrote:
| This is already the case for some of the very low-volume
| stops on that line. For non-express trains a combination of
| the following is currently (or at least was pre-covid) in
| use, with the mix varying throughout the day:
| * stop more or less everywhere * stop only at larger
| stations * even/odd stopping at small stations
|
| The scheduling already seems pretty clever, and that's just
| from observing as a passenger. I suspect behind the scenes
| there's a whole lot more to it that's not obvious to
| someone who is just trying to get to work.
| noneeeed wrote:
| Yep, there are whole departments of people who work hard
| to make the scheduling on railways work as well as
| possible. People always like to complain, but they always
| ignore the fact that the timetable has to try and satisfy
| a huge number of people with often very different needs,
| on networks with some very fixed constraints that are
| expensive and difficult to change.
| traceroute66 wrote:
| Yes, this was the sort of thing I was thinking for London.
| Not "express" per-se, but "missing stops" (i.e. just like
| what happens when stations are closed for platform
| maintenance during normal ops).
| noneeeed wrote:
| You can definitely do that.
|
| However on something like the underground that would
| complicate the "turn up and go" approach that most people
| take to the tube if you start skipping different sets of
| stations on different trains.
|
| It's something that's done, but I'm not sure how well it
| would scale on the tube if you did it a lot. Each train
| would need to miss roughly the same number of stops to
| prevent blockages or you need more passing places. With
| the small gaps between many tube trains the margin of
| error for scheduling can be very small.
|
| I think it's one of those things that works, but the
| advantage for the vast majority of people would be pretty
| small compared to the complexity and added fragility it
| would introduce if you tried to do it a lot.
| jon-wood wrote:
| Not without passing places, because you can't miss a stop
| without the train in front of you also missing it, at least
| without an eye watering body count.
| pavon wrote:
| Depends on how closely you are trying to run those
| trains! If they are both skipping every other stop, they
| will both have the same mean speed, and thus shouldn't
| have to pass one another if there is sufficient initial
| spacing.
|
| For example, in the simple case where the stations are
| evenly spaced, if train B arrives at station 1 at the
| same time that train A arrives at station 2, then they
| will leave at the same time and arrive at stations 3 and
| 4 respectively at the same time, and never catch up with
| each other.
| TheOtherHobbes wrote:
| A high speed line with passing places is a non-starter.
|
| The signalling barely works at the best of times. It's
| literally a museum of technologies, from the pneumatic to the
| electronic, and it's one of the most common points of failure
| on the network.
|
| But when it's working it's been improved to the point where
| there's almost no spare line capacity at peak times.
|
| And if you're making new tunnels it's so difficult and
| expensive to get a Tunnel Boring Machine into place that it
| makes no sense to bore short sections.
|
| Crossrail is supposed to be London's east/west express line.
| Obviously it's not ideal for District Line users, but it
| should free up some peak hour capacity for Circle and
| Hammersmith & City journeys which may translate to fewer
| District/Circle passengers.
|
| There's also talk of a north/south Crossrail 2.0, but that's
| unlikely to happen for decades.
|
| There are overground express sections on the Piccadilly
| (District) and Metropolitan (Jubilee) lines but they all keep
| the lines separate.
|
| There may well not be room for a tunnelled express in the
| central area. If it were up to me, I'd consider installing a
| good urban tram link from (say) Earls Court to Embankment.
| noneeeed wrote:
| > A high speed line with passing places is a non-starter.
|
| Yep. Not sure if I miss-worded something but that
| _definitely_ wasn 't what I was implying, just the
| opposite. That the whole point of HS2 is to separate the
| fast and slow trains so you don't need passing places
| (either at stations or otherwise) and so can actually run
| more trains on both the new HS [line and the existing line.
| nickdothutton wrote:
| One of the things you need to remember when thinking about the
| London Underground, is that it was a scheme that was ultimately
| unfinished. There were great plans between the world wars to
| extend it in size and functionality but ultimately these were
| all stopped by WW2 and an impoverished UK couldn't afford to do
| them afterwards. It was planned to extend the network well into
| Surrey, Kent and other places.
| Ichthypresbyter wrote:
| They also chose not to build many of the suburbs that the
| extended lines would have served, and instead to keep those
| areas rural as the Metropolitan Green Belt and to build new
| towns further away from London.
| tialaramex wrote:
| I grew up in the resulting green belt with restricted
| residential development of Metroland. Of course in practice
| what happens is that many people who "must" work in the
| City but have the salaries that come with that, choose to
| move, especially when they have young families, out to "the
| countryside" where the Metropolitan Line ends at e.g.
| Amersham.
|
| There you can walk from your house (with a view of woodland
| and fields across the valley) to a London Underground
| station (you probably don't actually catch an Underground
| train, even the express takes too long, you catch a
| "normal" commuter train serving the same station but these
| days it's the same price because it's the same system) in
| the morning and the reverse even evening. And your children
| grow up away from the noisy polluted city, but not so far
| away that you can't take them to see a stage show or one of
| the museums on a whim.
|
| Which is nice for them, but hardly screams "sustainable" as
| a society.
| willyt wrote:
| The tube has shorter times between trains than the New York
| subway. For example, Picadilly/Central/Victoria line trains run
| at <120 second headways on the central section. You couldn't
| control the gaps between trains precisely enough to demerge and
| remerge trains once you account for random factor of passenger
| loading and unloading and changing gaps between trains as they
| accelerate and decelerate between stations. Better to build a
| whole separate line, in fact this has been done already, the
| Victoria line is pretty much the express version of the
| Piccadilly line and likewise Crossrail will be the express
| version of the Central line.
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