10 ms·

Comments so far are not discussing what makes this light rail “very” light, so here’s an excerpt. The project claims to cost half of “normal” light rail. > The

• jsnell 1y ago
  These things are tiny! I've traveled in larger airport shuttles. It feels like that's putting this into a really awkward place in the tradeoff space. Trams work because they can scale higher than buses. That scale comes at the cost of more up-front infrastructure, much less flexibility, and needing dedicated lanes. So cities don't have trams everywhere, but they're only installed on routes that can support the scale. For these you still have the up-front investment (just less of it) and inflexibility, but don't get the efficiencies of scale due to how small the capacity is. Is this really just a bet that they can get autonomous tram-driving on city street approved a decade+ sooner than autonomous buses?
  • bluGill 1y ago
    Tiny might make sense if they are running every 2 minutes and thus getting their capacity via frequency. However there is no reason to think they will do that. (if they were running anywhere near that frequent overhead wire would be a lot cheaper than a battery on every tram)
    • bardak 1y ago
      Yeah but you could do that with a bus today without miltiions in infrastructure spending
      • scott_w 1y ago
        Not really because buses get stuck in traffic all the time because there’s a point where they need to share roads with cars. Once you spend the money on segregating buses entirely, you’re at the same level as the tram line. Also, because of the expensive infrastructure that can only be used by trams, there’s a permanence there that prevents future politicians from ripping it out to put more cars on for a quick political win with drivers. Going back to point 1: having a line means that any route needs to be properly planned because you never have an escape hatch of “just stick them on the road.” Example: where I live, the council installed a bus lane and a cycle lane. Where it pinches in (planning fuck up), it dumps all the traffic into a shared route with 2 roundabouts and 5 exits, each with an insane amount of traffic coming to or from them. Buses that are forced to use that route are always late. It takes me just as long to drive as it does to take the bus, faster if you factor in me waiting for a late bus.
        • vidarh 1y ago
          Trams very often still share the road with cars.
          • jonwinstanley 1y ago
            The Nottingham tram, not far from Coventry, usually only shares road with cars in the city centre which is mostly pedestrianised. So mostly avoids commute traffic.
          • scott_w 1y ago
            Not for all of the route, typically. Metrolink only in the city centre then it turns into a Metro line for the rest of the commuter route.
  • deleted 1y ago
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  • Veedrac 1y ago
    Trams don't actually scale higher than busses; the highest ridership BRTs have far more ridership than the highest ridership light rail. The key thing that makes it work is having a dedicated right of way. I expect busses get a bad rap as a scaled transit solution mostly because they have to share the roads so often. But it's indeed an advantage of light rail that it's a lot harder to make that mistake with it.
    • laurencerowe 1y ago
      Those BRTs will have lower passenger/operator ratios though since trams tend to be bigger than articulated buses and are frequently coupled together for busier routes. I definitely agree that the dedicated right of way is the main thing. It's why some of San Francisco's trams are so slow outside of the city centre (where they run in a tunnel) and why Manchester's trams are so slow through the city centre (where they run at surface level sharing the street with pedestrians.)
      • scott_w 1y ago
        Absolutely! I’ve used the Manchester Metrolink and it definitely slows down in the city centre. It does speed up a lot (and likely beats bus in rush hour) when you’re off the streets, which makes it an incredible commuter option!
        • laurencerowe 1y ago
          Much of it is built on repurposed heavy rail lines and those sections are great. The Eccles Line through Salford Quays is horribly slow and windy though which was a pain for commuting to Media City from south east Manchester. I believe the new Trafford line improves things somewhat but Manchester really needs much more heavy rail capacity.
          • rjsw 1y ago
            The line out to the airport isn't using an old rail line and is fairly slow.
  • ehnto 1y ago
    I think the up front investment is quite literally the problem this is solving for. If it weren't, you would just use light rail. The ability for the tracks to be laid so shallow is in my view, the entire innovation and cost is the reason for this approach.
  • pantalaimon 1y ago
    If higher capacity is needed you can always link multiple units together
    • closewith 1y ago
      In CVLR, you actually cannot as the extreme bogey angles mean they can only operate individually. You also can't order longer cars. You can run them at high frequency though.
      • mhandley 1y ago
        With computerized control and a comms link between the vehicles, you could probably have one vehicle follow 1m behind another, so they are effectively a train. If you still have a driver at all, you only need one in the front vehicle.
        • closewith 1y ago
          I don't think you could do that for CVLR specifically as it's not segregated from traffic and the second car would have to react individually to vehicles, pedestrians, roundabouts, etc.
          • mhandley 1y ago
            If it's really just 1m behind, it doesn't need to respond individually to anything except pedestrians. And you can solve that with some extensible tapes that actually do connect the vehicles to prevent pedestrians walking between them.
    • analog31 1y ago
      Linking multiple units means making the stations longer. A more likely scenario is to deploy more units and deal with staffing by migrating to autonomous operation.
  • brnt 1y ago
    Buses on dedicated lanes are OK indeed. However, buses are simply not as comfortable as trams: roads unless in tiptop shape are not as smooth as rail, and bus drivers always take corners too fast. Having to hold on to something discards it from my preferred list of solutions.
  • youngtaff 1y ago
    Have recently read Gareth Dennis’ How Railways will fix the Future… It’s a worthwhile read BTW I suspect these are too small to carry a significant number of passengers per hour They’ll also probably never be autonomous as the challenge with autonomous is less the driving and more with passengers getting on and off, getting trapped etc
  • James_K 1y ago
    I'd assumed the point of them was that you can take the several cars of a tram and split them up to have more frequent services. Though I suppose this would compound with the cost of having a driver on each car, potentially cancelling some of the gains from cheap installation. As for the point of automation, I think the tram can probably be a lot easier than the bus because of the human factor. It seems safer, so legislators will be more willing to legalise it and residents less likely to complain. Also, you've got rails in the road that clearly mark the route of the tram which make it more visible than an automated bus. Most of these automated taxi companies still have a human supervising the process, and I imagine that could be employed here to good effect and with fewer or faster manual interventions than would otherwise be needed. Even if all that falls through, I'm not gonna complain about it. We sorely need more public infrastructure in the UK. Even if an experiment like this fails, at least you actually get a tram line and experience out of it. Much better than a project which sucks up million then gets cancelled. (Cough cough HS2.)
  • chgs 1y ago
    Trans don’t need dedicated lanes, not sure where you got that idea from. Trains do. Buses however are slow (in London about the same as walking) and (outside London) prone to vanishing on timetable changes. Closing a rail link is tricky, you can be confident that if you live near a tram stop it will be there in 10 years. 60% of our local (say 10 mile radius) buses have been removed in the last decade, removing entire villages from service. A rail solution allows you to read, a bus throws you around everywhere and makes you sick.
    • IshKebab 1y ago
      Trams can be removed too. Bristol used to have trams. I doubt it is alone. I definitely feel like trams are a weird technical solution to a policy/perception problem. On a technical level I don't think there's that much to recommend them over buses with bus lanes. It's just that governments never put bus lanes the whole way like you are forced to do with a tram.
      • hgomersall 1y ago
        Trams are much smoother than buses. I suspect that a bus can be made as comfortable as a tram with active suspension optimising ride quality, but I've never come across one. Jerky starts and stops, swinging around, kneeling for (dis)embarkation; these all make the ride unpleasant for users. Trams exclude those at the cost of additional up front infrastructure costs. I can easily read a book on a tram. No chance on a bus (unless we want vomit all over the seats).
        • IshKebab 1y ago
          I agree, but I don't think that really matters. I mean nobody is going to spend millions on a tram just because it's a bit smoother. It's a nice bonus; not a reason to build trams.
          • hgomersall 1y ago
            On the contrary, it's the reason we should build more trams. If the objective is to have more people using public transport, then we need to make them as nice as possible for people to use. Comfort is the user facing benefit of trams.
  • Simon_O_Rourke 1y ago
    This is such a typical American sneer at public transport. It's tiny, how it possibly carry all those 2x4s, powertools and sheets of plywood when I'm out doing manly things. I'd better go buy that monster truck so I can look like a real man.
    • JdeBP 1y ago
      In many non-North American cities one needs tiny. Big stuff just does not fit.
    • imtringued 1y ago
      A normal public transit bus has twice the seats and doesn't need rails.
      • JdeBP 1y ago
        Yes and no. Yes, this is smaller than the double-deckers in Coventry, that you can even do an eyeball comparison with if you watch the ironic publicity video mentioned in https://news.ycombinator.com/item?id=44217231 https://news.ycombinator.com/item?id=44217231 and keep your eyes peeled for the buses queued up at those temporary traffic lights in the background. No, it's roughly on a par with the single-deckers, though, and there are quite a lot of those used by the local bus operators.
      • ericmay 1y ago
        In the US a bus is a strictly worse version of the private car. Walking/biking/rail are effectively category differences so they don’t compete on the same playing field as a car and bus will. It’s very important for public transportation officials in particular to understand this, because not understanding it will continue the car-only suburban development until we run out of money and economic physics dictates how we do transportation but with insane costs in the meanwhile.
    • JSR_FDED 1y ago
      I guess you don’t need much space to dip your baguette in a cuppa tea
  • jeroenhd 1y ago
    Trams can share lanes with normal car traffic. There's still a massive cost in terms of infrastructure (especially the overhead lines, utilities that need to get out of the way for the rail base, that sort of thing), but this project has a detailed description of why those aren't a problem for this project. The tram they show in the animation also very much has a driver in the front. If they can deliver on what they show in their demos, I don't see why the size of the trams or the infrastructure should be a problem. All the expensive stuff has been thought about, the system barely takes up any extra space, and the system is capable of scaling up by just sending more vehicles into service.
    • notahacker 1y ago
      Generally I'm in favour of this sort of project, but having lived in Coventry (albeit a while ago) I'm a little sceptical: it's basically just adding a lot of infrastructure cost to what were low frequency suburban bus routes (the actual centre of Coventry is compact and walkable). You can run regular buses with similar capacity on batteries too, and divert them more easily.
      • JdeBP 1y ago
        See https://news.ycombinator.com/item?id=44217164 https://news.ycombinator.com/item?id=44217164 . Coventry actually does, right now, run quite an extensive network of electric regular buses, not only out of Pool Meadow but also the ones that circle the Trinity Street/Burges loop. And they had to divert them to build the demonstrator track for this.
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  • switknee 1y ago
    Buses have slightly lower capex but much higher opex from the perspective of the community. City street gets ripped up by buses, cyclists get caught under the bus and dragged for miles, children get asthma from the tire dust. It being easier to give trams priority at traffic lights and easier to make the tram autonomous are just added bonuses. Lower flexibility is actually a feature when it comes to mass transit: People will build density along rail lines because they assume the town won't rip them up, making the rail line more valuable over time. A bus route can be cancelled the day after a disruptive mayor is voted into office. I also don't see why you can't scale up the tram with additional cars, as long as you keep the lbs/sqft the same. 3 car trams are fine, 3 car busses are... not
    • stephen_g 1y ago
      Also higher OPEX from the operator's point of view - trams can carry a lot more passengers per driver, they're more efficient energy-wise, and the replacement cost for bus tyres is large compared to steel wheels that last way longer.
      • noodlesUK 1y ago
        Interestingly in this case the tram fits far fewer people than a typical British bus. A modern London route master fits a maximum of 87 people (standing and seated). This tram only fits 50 (standing and seated). I'm nonetheless certain that it will be a much nicer way to travel, but I'm not sure that the maths work out the way you might initially expect.
• brookst 1y ago
  Definitely the high points of the story. And to emphasize — 15m corner radius!
  • kps 1y ago
    Toronto has 11m loops. Newark 10m. Boston had 10m until a few years ago. This used to not be a problem anywhere.
• t_luke 1y ago
  It’s fairly obviously designed to avoid the issues which almost caused the cancellation of the new Edinburgh tram — spiralling costs caused by the need to move existing utilities under the deep track base. That crisis was probably as much to do with a badly formed set of contracts as with the technical issues themselves, but it’s still worth designing out.
  • robocat 1y ago
    Contracts that lock in a waterfall process. At last they were not trying to use agile!
    • chgs 1y ago
      I do wonder how much of the backlash against agile is driven by people who never experienced waterfall
      • 95014_refugee 1y ago
        I do wonder how much of the hate on “waterfall” is perpetuated by folks that never read the paper. It’s the “socialism” of development workflows…
        • robocat 1y ago
          Yeah, I was just being cheeky because I was trying to imagine software development models applied to large planned infrastructure. A nuclear power station built successfully using an Agile process would be something I'd like to read about.
      • mannykannot 1y ago
        The key issue appears to be how long it took to realize that existing infrastructure would present a showstopping cost. In practice, waterfall and agile are virtually indistinguishable in their ability to anticipate such issues early - they can, but doing so depends on factors independent of the differences in methodology.
      • 1y ago
• Animats 1y ago
  A 15 meter turning radius is tight, but not revolutionary. San Francisco's MUNI system's tightest turns are 45 feet, or 13.7 meters. The newer vehicles are designed for that, and the old PCC cars had to be modified to allow the trucks some extra rotation. The turning loop on Embarcadero near Market is that tight. There is much wheel screeching when a PCC car goes through that loop, because wheels have to slip to turn that tight. But it works.[1] Battery powered trams have real potential, now that batteries with 5 to 7 minute charging and large numbers of charging cycles are a thing. That's compatible with typical end of line holding times. Steel wheel on steel rail is low friction, and you get most of the energy used to go uphill back when you go downhill. This could work out. [1] https://youtu.be/XKN0MTCUSV0?t=265 https://youtu.be/XKN0MTCUSV0?t=265
  • seanmcdirmid 1y ago
    > Steel wheel on steel rail is low friction, and you get most of the energy used to go uphill back when you go downhill. If you were going up and down hills, would you still use steel wheel in steel rail unless you had some sort of cable to work with? I always thought the Muni did relatively level routes for that reason? The Lausanne m2 for example uses rubber (well, ideally you’d be able to just balance the train going up with the train going down, but that only works for simple inclines with limited stops). Actually, a battery powered rubber wheeled tram service on some sort of steep incline like SF’s cable car routes could get some wicked regen going down. Even if level, they could still get some regen from making stops.
    • brnt 1y ago
      Problem with rubber wheels in metros is absolutely atrocious air quality. I avoid them like the plague.
      • throwaway2037 1y ago
        How many rubber wheel metros exist? I only know of a few -- Paris is one, but not all lines. Where do you live such you need to "avoid them like the plague"?
• red_admiral 1y ago
  Heavy and Light Rail in the UK is also a safety distinction: Light Rail is limited in speed, drives on sight (exceptions apply) and a few other restrictions (https://www.orr.gov.uk/about/who-we-work-with/railway-networks/light-rail-tramways https://www.orr.gov.uk/about/who-we-work-with/railway-networ...). Trams are one example of Light Rail, but so is the Docklands Light Railway in London (an exception to "on sight" - it's automatic), as opposed the the Tube (underground) which is Heavy. But the Welsh "metro" project's "tram-trains" (Stadler Citylink) are also Light, even though their tracks into the valleys are very much not urban in the usual sense - the full valleys journeys are over one hour with the current trains and go through mostly rural areas with small towns.
• doctorpangloss 1y ago
  Why is it easier for cities to develop obsolete stuff than to eg, run their own Uber?
  • alternatex 1y ago
    Uber and mass transit are an apples and oranges comparison.
  • patmorgan23 1y ago
    What's the highest capacity vehicle Uber has ever operated? Because Tranist can move thousands of people with a single operator
    • doctorpangloss 1y ago
      In the whole universe of intellectually honest, valuable benchmarks for transportation, do you think ride sharing wins on zero? I’ll give you an important one as an example: door to door journey times. I support RTO, which is the best way to improve that metric for the average person, which is to say, I was hoping this would be a discussion for out of the box thinking. Or really, what do you invest millions of infrastructure bucks into? All of Uber was only a little more expensive than a single high speed rail line. Why can’t cities run ride share? Why would they run ride share worse than a train service?
      • tommoor 1y ago
        > All of Uber was only a little more expensive than a single high speed rail line Sure, if you don't count the vehicles and the roads – the actual _transportation_ bit
      • OJFord 1y ago
        > All of Uber was only a little more expensive than a single high speed rail line. And charges/charges more for the service rendered, and still makes a loss. And if the city would charge for the taxi service... Why run it when other operators can and do? And multiple operators can effectively compete.
• tuukkah 1y ago
  If you want a real tram that is compatible with existing street geometries, the really nice Škoda ForCity Smart Artic tram was developed to meet the requirements in Helsinki, which wanted a smooth modern tram even though there are 15m radius curves and 8% inclines in the old parts of the network. https://en.wikipedia.org/wiki/%C5%A0koda_Artic https://en.wikipedia.org/wiki/%C5%A0koda_Artic
• billytetrud 1y ago
  Eliminating "the need" for overhead wires seems like a terrible trade off when you're adding "the need" for expensive batteries and charging infrastructure.
  • scotty79 1y ago
    Overhead wires are not trivial. Charging is.
    • billytetrud 1y ago
      You're very wrong about that.
      • scotty79 1y ago
        Charging is just a point. Cables must be over entire track system. And if you at any point in time decide that cables are more economical you can always put them over any part of the track where you think it makes economic sense and use them to charge. If we had lithium batteries first there's be scarcely any overhead cables anywhere. Heck, in US they don't even bother with cables or batteries, just put a diesel generator and a tank on electric trains for decades now. But if you still believe I'm very wrong, please do elaborate.
    • deleted 1y ago
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