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.
South Kensington station's escalator replacement project
51–60 of 110 posts
Re: South Kensington station's escalator replacement project
#52Earlier quoted context omitted.
Could you have odd / even trains that miss stops?
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).
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.
Re: South Kensington station's escalator replacement project
#53Earlier quoted context omitted.
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 a…
Isn't the problem with automation on the tube less the technology but more the unions ?
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.
Re: South Kensington station's escalator replacement project
#54Earlier quoted context omitted.
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 cap…
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 e…
> 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.
Re: South Kensington station's escalator replacement project
#55It 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 morni…
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…
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.
Re: South Kensington station's escalator replacement project
#56It'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.
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!
Re: South Kensington station's escalator replacement project
#57I havent read the full article, but why is this the number 2 story on HN? Have I sorted incorrectly?
I've never known a hacker who didn't like trains and escalators.
Re: South Kensington station's escalator replacement project
#58It'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.
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)
Re: South Kensington station's escalator replacement project
#59It'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.
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 Und…
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...
Re: South Kensington station's escalator replacement project
#60The 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.wik…
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.
If you want a really interesting read, which is great at showing how a methodical enquiry is carried out is here: https://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.