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Comment by salynchnew

7 days ago

Note: This only seems to apply to driverless trains.

Depending on the system in questoin, this might be impractical or impossibly dangerous.

12 comments

salynchnew

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jrockway  7 days ago

I don't think there is any danger to running more frequent longer trains. Ultimately you are constrained by the signalling system; nobody is suggesting "just disable the tripcocks and plow through red signals". Modern systems use moving block cab signals, so are set up to succeed with high frequency. (But there are other problems, like terminal capacity, that can limit frequency. The MTA in NYC spent a ton of money giving the L CBTC to run 40+ tph... but the terminal at 8th Ave can't turn that many trains. Until that's fixed, the L will always be overcrowded.)

You can see whether the problem is being cheap or if it's actually a capacity issue. If weekend service sucks but peak hour service is good, then it's just being cheap. If rush hour can't handle passenger volumes, then you need a signal system / automation upgrade. (Or a parallel line!)

As a New Yorker, I'm very jealous of Vancouver's SkyTrain system. ("But NYC has the best metro in North America!!" Maybe...) The NYC subway has a lot of peak hour capacity. I hate traveling at peak hours. So that means I'm always standing in stations waiting 10 minutes for the next train. If I lived in Vancouver, then that would be 3 minutes. Sounds good to me!

I also agree with the author in that I'm not sure what elevated trains did to hurt people. I lived in Chicago next to the L for years. It never bothered me. It's nice to see out the window and look at something while you're in transit. And it's cheaper than building things underground. NYC apparently got rid of its elevated railways because of snow, so that's something to watch out for. But Chicago gets more snow and it does OK. (Having commuted on both systems in the snow, it's a mixed bag. Chicago doesn't shut down, but it's slow as people remember how to deal with snow. NYC can run on snow-free underground tracks, but sometimes the governor is like "fuck it, I'm cancelling all the trains anyway" and then you're just stuck.)

  • theluketaylor  7 days ago

    SkyTrain vs Seattle Link Light Rail is a fascinating contrast.

    SkyTrain works because of a virtuous cycle of attributes: Full grade separation enables automation. Automation enables many trains per hour. Many trains per hour with short trains still has tons of capacity. Short trains means lower costs for stations, which as the article notes is a huge portion of rapid transit costs. Lower cost means building more transit for the same budget, so more transit gets built. More transit with great headways results in transit being the mode of choice. Take any one of these elements out and you can still have a functioning transit system, but the magic is missing.

    Link light rail is so close to full grade separation but not quite there, so headways are limited by the grade crossing. With longer headways, bigger trains are needed to serve the same capacity. Bigger trains mean big stations and beefier, more expensive viaducts. Big stations are expensive.

    Link is gaining ridership and offering great service, but it's hard not to think if they had learned the full lessons from nearby Vancouver it would be even better (and cheaper).

  • crazygringo  7 days ago

    > I also agree with the author in that I'm not sure what elevated trains did to hurt people.

    They're horrifically ugly for pedestrians and city life generally. If you've been around the elevated subway tracks in Brooklyn, for example, they're not pleasant to be around. They block out the sun, they're incredibly noisy, they make the street claustrophobic, they definitely become streets to avoid unless necessary.

    Yes, they have a nice view if you're a passenger. But they make the city much, much worse for everyone below them.

    • kccqzy  7 days ago

      Oh yes. In Manhattan there were plenty of elevated lines that were dismantled because the people thought that they were too noisy and should be replaced with subways. The Second Avenue had an elevated train that was supposed to be replaced by a Second Avenue Subway, but the latter is only partially complete.

    • theluketaylor  7 days ago

      The elevated steel structures of the NYC subway and Chicago El have nothing in common with modern elevated rail. Modern concrete guideways are small and quiet.

      Melbourne is eliminating grade crossings with new guideways and creating linear park space underneath as they go.

  • troupo  7 days ago

    > I also agree with the author in that I'm not sure what elevated trains did to hurt people.

    I've only seen them in Hamburg. They are generally an eye-sore. And the area underneath them is somewhat unusable (like any area under a bridge): you can't really build anything there. So it's an eyesore above an eyesore.

jillesvangurp  6 days ago

There are plenty driverless trains in operations. Some have been running for decades. For example Toulouse in France has a metro without drivers since 1993. I was there a decade or so ago and sat in the front of the train on a bench in the front of the train staring out into the tunnel. Because there isn't a driver compartment. Really cool. They have some fences on the platform that align with the train doors for safety. The train lines up, people get in/out and it drives to the next station. Some airports have similar systems. This stuff has been possible for quite some time.

These days, you should be designing for autonomous operation for new infrastructure. Much easier when you design from the ground up. Not doing that could be an expensive mistake.

bobthepanda  6 days ago

I mean this is talking about construction of brand new lines, and in the Western world if you are building a brand new, totally separated line then automated is the no-brainer solution given high Western labor costs.