7 ms·

A short post on short trains

101 points by surprisetalk 1y ago

salynchnew 1y ago
Note: This only seems to apply to driverless trains. Depending on the system in questoin, this might be impractical or impossibly dangerous.
- jrockway 1y 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.)
  - troupo 1y 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.
  - PaulHoule 1y ago
    Off-peak the wait for trains seems like forever in NYC.
  - theluketaylor 1y 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).
  - mschuster91 1y ago
    > I also agree with the author in that I'm not sure what elevated trains did to hurt people. You need to either build them in right at the start of a new development or you gotta demolish a lot of housing - similarly to what was done in a lot of US cities when the highways were built [1]. [1] https://www.reuters.com/world/us/us-freeways-flattened-black-neighborhoods-nationwide-2021-05-25/ https://www.reuters.com/world/us/us-freeways-flattened-black...
  - 1y ago
- bobthepanda 1y 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.
- jillesvangurp 1y 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.
xnx 1y ago
> Small Train is Good Train In a few years I think we'll recognize that self-driving vans (in a few different sizes) are the best trains: cheaper than trains (and therefore lower environmental impact), completely flexible routing, and you can even let them use dedicated right of way if you want to increase capacity.
- sofixa 1y ago
  > cheaper than trains (and therefore lower environmental impact) How does that work? For the same amount of capacity, vans are not and probably never will be cheaper. Steel wheels on rails, with massive capacity, is just drastically more efficient, even with 0 driver costs. You'll still have much more maintenance (the tires, breaks, road) to do with a much higher number of vehicles.
  - skybrian 1y ago
    This will depend on density and what's already built. An extreme case: it wouldn't make sense to replace a large, rural school district's bus fleet with trains.
  - xnx 1y ago
    All trains, tracks, and stations are specially designed and built, which makes them very expensive. There is no mass-produced off-the-shelf solution like with cars and roads. Trains are unbeatable for inland freight between limited destinations, but don't make much sense for current day commuting or traffic patterns.
    - theluketaylor 1y ago
      There are off the shelf trains, tracks, and stations already. It's one of the key ways many european and asian operators deliver tons of transit for the dollar.
    - exasperaited 1y ago
      This is not really true. There are absolutely things in the rail system that are as “mass produced” as roads are. Railway platforms for example are a highly standardised form that has many other applications (loading and inspection bays, walkways etc.), trains are actually not only mass produced (e.g. by Bombardier) but are actually leased by their operators in Europe; there are five or six, I think, main ROSCOs —- rolling stock companies —- in the UK for example. There is a notable exception that might distort techie perception on this issue: BART. It implements many of its own standards, even down to track gauge. But it is absolutely an outlier (standardised track gauge, ironically, being the USA’s main contribution to the development of the railways, which it was otherwise late to). Almost everywhere else has rather interchangeable infrastructure and a lot of trans-national businesses.
thesz 1y ago
> if we run a system for smaller trains, we can build smaller stations for these trains, saving a huge amount on station costs. This costs us in reduced total capacity, but this can easily be made up for by increasing train frequency. There is a safe minimal distance between trains, in fact, a safe distance for a given speed. Shorter trains are not exempt from obeying it. You can make shorter trains more frequent at the expense of lowering traveling speed. What is the cap of throughput is due to these speed limitations is an exercise left for the author of the article.
- Denvercoder9 1y ago
  > What is the cap of throughput is due to these speed limitations is an exercise left for the author of the article. They already did that exercise: > 3-car trains running at 30-40 trains per hour (a normal peak frequency for automated or even some human-driven metro lines) reach a capacity of about 18,000 passengers per hour per direction, well above the expected demand of any American line that doesn’t go through Manhattan.
  - ghostly_s 1y ago
    Yes, they are assuming a best-case scenario. Driverless systems are very expensive for reasons that have little to do with the cost of the driverless trains, if you're not going to consider those variables this kind of armchair speculation is a waste of everyone's time.
    - decimalenough 1y ago
      They aren't though? If you're building a new line, fully driverless is pretty much the default these days, especially if the line is fully underground or elevated. What is incredibly expensive, though, is retrofitting a line designed for manual operation to run automatically instead.
      - odo1242 1y ago
        Well, a lot of systems exist that were initially designed for automatic operation but still end up becoming operated manually or partially manually due to safety concerns or politics. Washington DC Metro and BART are the two big systems I can think of that had this issue.
decimalenough 1y ago
Small trains and small stations are good until they aren't, and then you're screwed. Singapore built the orbital Circle MRT line exactly as the author wants: small trains (3 carriages, vs 6-8 on other line), small stations to fit these trains, frequent fully automated operation. However, the line turned out to be much more popular than planners anticipated, with the result that at rush hour, it's common to have to queue just to enter the platform where you need to wait for multiple trains to arrive before you can squeeze in. And the tricky bit is that there is essentially nothing you can do now to fix it. There's a hard physical limit (around 90 secs) on how fast the cycle of a train arriving, people getting on and off, and departing can get, and retrofitting all 30+ deep underground stations to be larger would be an insanely expensive and disruptive exercise.
- theluketaylor 1y ago
  That's true, but if you've kept a lid on construction costs as light metros tend to do, the public will embrace building new relief lines that bring more service to areas with moderate access. That adds big capacity you can then continue to grow into. Paris is a great example of this, they often just add whole new lines rather than trying to wring a bit more capacity from existing ones.
  - kaliqt 1y ago
    This makes a lot of sense to bring life to new districts naturally.
    - eru 1y ago
      Look into Streetcar Suburbs for a American examples. You could do worse than starting with https://en.wikipedia.org/wiki/Streetcar_suburb https://en.wikipedia.org/wiki/Streetcar_suburb
- bsder 1y ago
  > and retrofitting all 30+ deep underground stations to be larger would be an insanely expensive and disruptive exercise. But before this you had no idea that there was so much demand, right? It's quite a lot easier to sell a huge monetary upgrade on something oversubscribed rather than a huge monetary outlay that may be a complete white elephant.
bgnn 1y ago
it's all about capacity requirement. If the capacity demand is high, you might want to build really long trains and run them as frequently as possible (e.g. Istanbul Marmaray)
PaulHoule 1y ago
There's the analysis that, in the long run, operators are expensive which is an argument for automation or long trains.
- bluGill 1y ago
  Automation with short trains is similar price to long trains, but the short trains will run a lot more often and that will attract riders who have a choice of driving or not. If they miss their bus/train or have a long wait for their bus/train they will fix that by driving. However if they try transit and service is frequent they will realize that transit works just fine and so they will choose to not drive even though they can.
  - theluketaylor 1y ago
    Frequency is freedom. Nothing feels slower than standing still. Sitting in congested traffic sucks, and so does loitering on a train platform or a bus stop. When the vehicle arrives so quickly you don't even consider the timetable or care if you just miss a train transit is an easy choice.
IIAOPSW 1y ago
Something I've been thinking about lately is short trains but long platforms. Basically, you split the length of the trains in half and then split the platform into two boarding areas. In this way trains can be scheduled even closer together than the the 3-min physical limit of of signalling because the one coming in behind doesn't need to wait for the one ahead to leave the station first. Its therefore possible to schedule several different services on the same two-track system such that they all skip a large fraction of stops (and thus run faster), but every station is still reachable from every other without transferring. A simple example would be 3 services on the same line that follow a repeating pattern every 3 stations. ==[A]==[B]==[C]==[A]==[B]==[C]==. The service (AB) stops on the stations labelled [A] and [B] (skipping C). The service (AC) stops on the stations labelled [A] and [C] (skipping B). The service labelled (BC) stops on the stations labelled [B] and [C] (skipping A). In this manner, all three services skip over 33% of the stops on the line, but no matter what your origin and destination, it is always possible to travel from an [A] station to a [B] or [C] station (or another [A] station), and likewise from a [B] or [C] station. To the extent I've worked out the logistics of this, if you allow for trains to catch up but not pass each other at the platforms, you can push this idea as far as only stopping at 2-in-5 stations without sacrificing headways or capacity. Just a weird thing thats been taking my attention lately.
- burkaman 1y ago
  This is how it already works in Europe (at least in Austria and Germany, but I assume elsewhere in Europe as well). You will also find long trains that split in half mid-journey, so you need to make sure you get in the right car or you'll go to the wrong place. Edit: I guess it's not exactly what you're saying, in Europe you will find platforms split into several sections with multiple trains to board, but they'll be for different lines with different destinations.
  - IIAOPSW 1y ago
    yeah, what I have in mind is a variation / generalization of skip-stop. https://en.wikipedia.org/wiki/Skip-stop https://en.wikipedia.org/wiki/Skip-stop
- 1y ago
kccqzy 1y ago
The author spends a lot of words talking about short trains and Jersey City, but didn't once mention the Hudson Bergen Light Rail which was at least built in recent memory? I mean other than driverless operation it seems to check all the boxes. And in that light, I really fail to see the novelty in this argument; it's basically the multi-decade-old argument that building light rails is cheaper and better than real metro or heavy rail.
- bluGill 1y ago
  there is nothing new about trains - we need to stop looking for innovation and just build them with small incremental improvements. The only useful innovation since 1920 is full automation (though I'm going to call high speed rail incremental since it is mostly a lot of small improvements on the way - this is debatable). Even full automation was a lot of incremental improvements. That said, full automation is a major game changer because it enables short trains with high frequency which you would otherwise struggle to afford. Don't build light rail, build light metro which is a small cost more (build a metro with light rail) but now you can have full automation.
- woodruffw 1y ago
  I also thought this omission was conspicuous. The author has some reasonable points, but the sections on NYC and NJ felt like political wish (spite?) casting: just about the only state in the US that struggles more to build mass transit than NY is NJ. The HBLR is a rare survivor in an otherwise very crowded graveyard of NJ mass transit projects.
frankfrank13 1y ago
jersey and short trains makes me think of the newark air train, easily the worst train in the US
- returningfory2 1y ago
  Good news is that it’s being rebuilt/replaced!
bashkiddie 1y ago
Munich is a counter example: It has many lines passing through (almost) 11 stations. They run at maximum speed of 40 trains per hour. It is a traditional block signal system with each block being shorter than a train - so they can run trains packed into tighter space. Each train opens left and right doors simultaneously so people can board and exit at the same time. Boarding still takes time. It is overcrowded at rushhour and brakes down regularily (a train being at a station for too long blocks all proceeding trains). And at Oktoberfest time, the stations are soo crowded that boarding takes longer. Munich is planning on building a second subway route. It just does not have the money nor the space to build one. There has been discussion on building a second tunnel below the first, or on enabling the common train system for overflow by suburban trains -- by installing more signals to run more tightly packed.
- agurk 1y ago
  The second route is currently being built in Munich [0], with work started in 2017. I recently watched a youtube video by The B1M about rail projects in Germany that included a long section about the currently ongoing works in Munich [1] that gives a good visual overview. [0] https://db-engineering-consulting.com/en/projects/munichs-second-core-s-bahn-route/ https://db-engineering-consulting.com/en/projects/munichs-se... [1] https://www.youtube.com/watch?v=bPDQdnT-RaY https://www.youtube.com/watch?v=bPDQdnT-RaY
renewiltord 1y ago
In the US you can't do it, because the unions lobby to have two people per train and the people really like unions. EDIT: Listen, you can downvote me but it's true https://www.etany.org/statements/impeding-progress-costing-riders-opto https://www.etany.org/statements/impeding-progress-costing-r... "Facts don't care about your feelings"
- bobthepanda 1y ago
  New York MTA is not representative of the whole US. DC Metro for example has one driver per train. AirTrain JFK is automated with no driver.
ethagnawl 1y ago
Why are tech dudes so hung up on homelessness? Also, the reference to it was so callous and would seem to reveal a complete lack of empathy: NYC has too many homeless people; let's build a metro in Jersey City in order to make Jersey City ... more of a thing and not even attempt to address the "problem" in any substantive way. It's also a feat of mental gymnastics to put European infrastructure on a pedestal while ranting about NY's taxes and, more broadly, the US' difficulties building infrastructure.
kazinator 1y ago
Is it written in stone that a train must fit entirely into a station so that all doors face the platform and can be open simultaneously? If we think of the station as the head of a Turing machine ...
- lmm 1y ago
  > Is it written in stone that a train must fit entirely into a station so that all doors face the platform and can be open simultaneously? When you're building high capacity transit for dense cities, yes. You could stop the train twice in the same station, sure, but at that point you have to stop for twice as long (probably a little longer than that as your riders will get confused), so your train takes ~twice as long to get anywhere and can therefore carry ~half as many people.
- bobthepanda 1y ago
  It is really a safety and dwell time thing. The moment you have only some cars platforming, then people need to make sure they are in the right car, and if, say, a slow-walking elderly person is in the wrong car, then her getting into the right one to get off wastes a lot of time.
- Cthulhu_ 1y ago
  It's not written in stone, but if you don't, people will be moving through the train and pushing to get out sooner. Public transit is a test of patience and a study in human herd behaviour.
- rsynnott 1y ago
  Some metro lines have this (stations too short to fit the whole train). It is _not ideal_. Like, in some cases it's probably unavoidable, but it would not be your first choice, from a passenger ergonomics pov.
Peteragain 1y ago
Loebner (of the prize fame) patented the idea of a rollercoaster tube system. Stations on the surface, going underground and up to the next station. Saves power and reduces the curb to platform time. Just thought I'd put that out there...
- bobthepanda 1y ago
  Some train lines are designed like this although obviously much more gradually like the Victoria Line in London. In practice it’s pretty negligible.
- Cthulhu_ 1y ago
  But then you'd need stations and part of the rails on the surface, taking up valuable real estate. Versus a small entrance building. Not sure how or how much it would save power either.
curtisblaine 1y ago
Incredibile that noise, visual impact, potential disruptions to residents and property devaluing are not even mentioned in the article.
- jillesvangurp 1y ago
  Compared to car traffic, rail is a lot nicer. Putting it in place is indeed disruptive; just like any kind of infrastructure work. Once you have it, property values tend to go up, not down due to better transport options.
  - curtisblaine 1y ago
    Not if the railway obstructs your view from the windows.
tgsovlerkhgsel 1y ago
I think this observation is undervalued: > Wait times are the second-most underrated component in making metro systems effectively faster (right after street to platform time). Street to platform time made using public transit annoying in several Asian capitals. Wait times are the main reason why I often hate traveling with public transit even in a city with one of the best public transit systems - if you aren't planning your life around the transit schedule, the wait time is essentially an unpredictable part of your travel time (and if you do plan around it, it's one more annoying thing to deal with). If you leave your doctor's office, and you have a 10 minute train home that goes every 30 minutes, then you really have a 10-40 minute train home - so for practical purposes, you essentially have a 40 minute train. Once unreliability or delays become frequent enough to start being a factor to consider, this could easily turn it into a 70 minute train. Another big factor is the time between the actual start/end of the trip and the nearest station. Even with near-zero street-to-platform time (e.g. busses/trams) and reliable, reasonably frequent public transit, once you add it all up, a bicycle often ends up being faster than even excellent public transit.
- xandrius 1y ago
  To be fair a bicycle is private transit but I agree with the rest.
thom 1y ago
Of course coming from the UK there is nothing that strikes horror into my heart more than being at a crowded platform waiting for a late train and it pulling up with half or quarter the carriages that you expected. Feels like a luxury to imagine a system where you’d get to tweak these variables until things work rather than trains being a force of nature.
lbriner 1y ago
I feel like this is one of those articles that claims some clever idea on paper but without experience of how this would actually work IRL but IDK if the OP has more experience than me so I will assume the best. Others have already pointed out some of the practical things that would limit what you can achieve with shorter trains like minimum headway between trains and the congestion that would occur after a delay where you would expect people to wait for maybe 10 short trains to arrive and depart before you could get on. There are other problems. The cost of the smaller trains means if e.g. 2 carriages each, then every other car is a driving vehicle with motors and control equipment. On longer trains, this could be 1 in 3 or 1 in 4. Each of these not only requires regular maintenance (so that's doubled the maintenance requirements) but also creates massive congestion issues in maintenance yards. Commonly, 1 or 2 full trains fit in each siding so getting most trains out if e.g. one is broken down is usually easy enough. Imagine having to move 3 or 4 separate smaller trains out of the way, they are not automated in the yards. Most people would be very unhappy knowing that they might be alone on a train, which is a main reason why operators are not quick to get rid of all staff. But currently, a single driver and conductor is close by for, maybe, 8 carriages. This would double if you needed a single attendent on each 2 carriage train. The signalling is very heavily designed around traditional trains with its delay after passing a signal. 4 x 2 carriage trains would utilise more signalling capacity/time than 1 x 8 carriage train. If these were all coming from the same location and needed to return, that would also need a lot more platforms so that the following trains don't block the first trains in terminal platforms. This is already a major problem at most UK terminal stations so that is largely unsurmoutable. I also heavily question the idea that station cost is largely dependent on platform length. On most surface stations, platforms are relatively easy to construct and whether they are 4 carriages or 12 carriages long still require a station building or 2, some ticket machines and CCTV etc. For elevated railways that is more likely to be true maybe. So yeah, like someone else said, we are unlikely to come up with ideas that 1000 other engineers haven't already asked, the easier problems to solve are around planning, design, legal rights for infrastructure projects etc. since these tend to eat up sometimes decades and billions of dollars.
rkachowski 1y ago
> Is this one London or Copenhagen? There’s literally no way to know! There are two passing vehicles in the background, based on the direction of movement they seem to be driving on the left. Assuming the image is not reversed this would imply London... of course, this could also be discovered by recognising literally anything else
tharmas 1y ago
Wouldn't building longer platforms (more expensive at the time) be cheaper in the long run than building an additional line to handle the excess demand that will be sure to come as a result of building it in the first place. Metro lines are built in the first place because of demand but once built demand increases also, does it not? You can run short trains with longer platforms but its more difficult the other way around.

101 points by surprisetalk 1y ago

Note: This only seems to apply to driverless trains. Depending on the system in questoin, this might be impractical or impossibly dangerous.

jrockway 1y 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.)
- troupo 1y 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.
- PaulHoule 1y ago
  Off-peak the wait for trains seems like forever in NYC.
- theluketaylor 1y 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).
- mschuster91 1y ago
  > I also agree with the author in that I'm not sure what elevated trains did to hurt people. You need to either build them in right at the start of a new development or you gotta demolish a lot of housing - similarly to what was done in a lot of US cities when the highways were built [1]. [1] https://www.reuters.com/world/us/us-freeways-flattened-black-neighborhoods-nationwide-2021-05-25/ https://www.reuters.com/world/us/us-freeways-flattened-black...
- 1y ago
bobthepanda 1y 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.
jillesvangurp 1y 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.

xnx 1y ago

> Small Train is Good Train In a few years I think we'll recognize that self-driving vans (in a few different sizes) are the best trains: cheaper than trains (and therefore lower environmental impact), completely flexible routing, and you can even let them use dedicated right of way if you want to increase capacity.

sofixa 1y ago
> cheaper than trains (and therefore lower environmental impact) How does that work? For the same amount of capacity, vans are not and probably never will be cheaper. Steel wheels on rails, with massive capacity, is just drastically more efficient, even with 0 driver costs. You'll still have much more maintenance (the tires, breaks, road) to do with a much higher number of vehicles.
- skybrian 1y ago
  This will depend on density and what's already built. An extreme case: it wouldn't make sense to replace a large, rural school district's bus fleet with trains.
- xnx 1y ago
  All trains, tracks, and stations are specially designed and built, which makes them very expensive. There is no mass-produced off-the-shelf solution like with cars and roads. Trains are unbeatable for inland freight between limited destinations, but don't make much sense for current day commuting or traffic patterns.
  - theluketaylor 1y ago
    There are off the shelf trains, tracks, and stations already. It's one of the key ways many european and asian operators deliver tons of transit for the dollar.
  - exasperaited 1y ago
    This is not really true. There are absolutely things in the rail system that are as “mass produced” as roads are. Railway platforms for example are a highly standardised form that has many other applications (loading and inspection bays, walkways etc.), trains are actually not only mass produced (e.g. by Bombardier) but are actually leased by their operators in Europe; there are five or six, I think, main ROSCOs —- rolling stock companies —- in the UK for example. There is a notable exception that might distort techie perception on this issue: BART. It implements many of its own standards, even down to track gauge. But it is absolutely an outlier (standardised track gauge, ironically, being the USA’s main contribution to the development of the railways, which it was otherwise late to). Almost everywhere else has rather interchangeable infrastructure and a lot of trans-national businesses.

thesz 1y ago

> if we run a system for smaller trains, we can build smaller stations for these trains, saving a huge amount on station costs. This costs us in reduced total capacity, but this can easily be made up for by increasing train frequency. There is a safe minimal distance between trains, in fact, a safe distance for a given speed. Shorter trains are not exempt from obeying it. You can make shorter trains more frequent at the expense of lowering traveling speed. What is the cap of throughput is due to these speed limitations is an exercise left for the author of the article.

Denvercoder9 1y ago
> What is the cap of throughput is due to these speed limitations is an exercise left for the author of the article. They already did that exercise: > 3-car trains running at 30-40 trains per hour (a normal peak frequency for automated or even some human-driven metro lines) reach a capacity of about 18,000 passengers per hour per direction, well above the expected demand of any American line that doesn’t go through Manhattan.
- ghostly_s 1y ago
  Yes, they are assuming a best-case scenario. Driverless systems are very expensive for reasons that have little to do with the cost of the driverless trains, if you're not going to consider those variables this kind of armchair speculation is a waste of everyone's time.
  - decimalenough 1y ago
    They aren't though? If you're building a new line, fully driverless is pretty much the default these days, especially if the line is fully underground or elevated. What is incredibly expensive, though, is retrofitting a line designed for manual operation to run automatically instead.
    - odo1242 1y ago
      Well, a lot of systems exist that were initially designed for automatic operation but still end up becoming operated manually or partially manually due to safety concerns or politics. Washington DC Metro and BART are the two big systems I can think of that had this issue.

decimalenough 1y ago

Small trains and small stations are good until they aren't, and then you're screwed. Singapore built the orbital Circle MRT line exactly as the author wants: small trains (3 carriages, vs 6-8 on other line), small stations to fit these trains, frequent fully automated operation. However, the line turned out to be much more popular than planners anticipated, with the result that at rush hour, it's common to have to queue just to enter the platform where you need to wait for multiple trains to arrive before you can squeeze in. And the tricky bit is that there is essentially nothing you can do now to fix it. There's a hard physical limit (around 90 secs) on how fast the cycle of a train arriving, people getting on and off, and departing can get, and retrofitting all 30+ deep underground stations to be larger would be an insanely expensive and disruptive exercise.

theluketaylor 1y ago
That's true, but if you've kept a lid on construction costs as light metros tend to do, the public will embrace building new relief lines that bring more service to areas with moderate access. That adds big capacity you can then continue to grow into. Paris is a great example of this, they often just add whole new lines rather than trying to wring a bit more capacity from existing ones.
- kaliqt 1y ago
  This makes a lot of sense to bring life to new districts naturally.
  - eru 1y ago
    Look into Streetcar Suburbs for a American examples. You could do worse than starting with https://en.wikipedia.org/wiki/Streetcar_suburb https://en.wikipedia.org/wiki/Streetcar_suburb
bsder 1y ago
> and retrofitting all 30+ deep underground stations to be larger would be an insanely expensive and disruptive exercise. But before this you had no idea that there was so much demand, right? It's quite a lot easier to sell a huge monetary upgrade on something oversubscribed rather than a huge monetary outlay that may be a complete white elephant.

bgnn 1y ago

it's all about capacity requirement. If the capacity demand is high, you might want to build really long trains and run them as frequently as possible (e.g. Istanbul Marmaray)

PaulHoule 1y ago

There's the analysis that, in the long run, operators are expensive which is an argument for automation or long trains.

bluGill 1y ago
Automation with short trains is similar price to long trains, but the short trains will run a lot more often and that will attract riders who have a choice of driving or not. If they miss their bus/train or have a long wait for their bus/train they will fix that by driving. However if they try transit and service is frequent they will realize that transit works just fine and so they will choose to not drive even though they can.
- theluketaylor 1y ago
  Frequency is freedom. Nothing feels slower than standing still. Sitting in congested traffic sucks, and so does loitering on a train platform or a bus stop. When the vehicle arrives so quickly you don't even consider the timetable or care if you just miss a train transit is an easy choice.

IIAOPSW 1y ago

Something I've been thinking about lately is short trains but long platforms. Basically, you split the length of the trains in half and then split the platform into two boarding areas. In this way trains can be scheduled even closer together than the the 3-min physical limit of of signalling because the one coming in behind doesn't need to wait for the one ahead to leave the station first. Its therefore possible to schedule several different services on the same two-track system such that they all skip a large fraction of stops (and thus run faster), but every station is still reachable from every other without transferring. A simple example would be 3 services on the same line that follow a repeating pattern every 3 stations. ==[A]==[B]==[C]==[A]==[B]==[C]==. The service (AB) stops on the stations labelled [A] and [B] (skipping C). The service (AC) stops on the stations labelled [A] and [C] (skipping B). The service labelled (BC) stops on the stations labelled [B] and [C] (skipping A). In this manner, all three services skip over 33% of the stops on the line, but no matter what your origin and destination, it is always possible to travel from an [A] station to a [B] or [C] station (or another [A] station), and likewise from a [B] or [C] station. To the extent I've worked out the logistics of this, if you allow for trains to catch up but not pass each other at the platforms, you can push this idea as far as only stopping at 2-in-5 stations without sacrificing headways or capacity. Just a weird thing thats been taking my attention lately.

burkaman 1y ago
This is how it already works in Europe (at least in Austria and Germany, but I assume elsewhere in Europe as well). You will also find long trains that split in half mid-journey, so you need to make sure you get in the right car or you'll go to the wrong place. Edit: I guess it's not exactly what you're saying, in Europe you will find platforms split into several sections with multiple trains to board, but they'll be for different lines with different destinations.
- IIAOPSW 1y ago
  yeah, what I have in mind is a variation / generalization of skip-stop. https://en.wikipedia.org/wiki/Skip-stop https://en.wikipedia.org/wiki/Skip-stop
1y ago

kccqzy 1y ago

The author spends a lot of words talking about short trains and Jersey City, but didn't once mention the Hudson Bergen Light Rail which was at least built in recent memory? I mean other than driverless operation it seems to check all the boxes. And in that light, I really fail to see the novelty in this argument; it's basically the multi-decade-old argument that building light rails is cheaper and better than real metro or heavy rail.

bluGill 1y ago
there is nothing new about trains - we need to stop looking for innovation and just build them with small incremental improvements. The only useful innovation since 1920 is full automation (though I'm going to call high speed rail incremental since it is mostly a lot of small improvements on the way - this is debatable). Even full automation was a lot of incremental improvements. That said, full automation is a major game changer because it enables short trains with high frequency which you would otherwise struggle to afford. Don't build light rail, build light metro which is a small cost more (build a metro with light rail) but now you can have full automation.
woodruffw 1y ago
I also thought this omission was conspicuous. The author has some reasonable points, but the sections on NYC and NJ felt like political wish (spite?) casting: just about the only state in the US that struggles more to build mass transit than NY is NJ. The HBLR is a rare survivor in an otherwise very crowded graveyard of NJ mass transit projects.

frankfrank13 1y ago

jersey and short trains makes me think of the newark air train, easily the worst train in the US

returningfory2 1y ago
Good news is that it’s being rebuilt/replaced!

bashkiddie 1y ago

Munich is a counter example: It has many lines passing through (almost) 11 stations. They run at maximum speed of 40 trains per hour. It is a traditional block signal system with each block being shorter than a train - so they can run trains packed into tighter space. Each train opens left and right doors simultaneously so people can board and exit at the same time. Boarding still takes time. It is overcrowded at rushhour and brakes down regularily (a train being at a station for too long blocks all proceeding trains). And at Oktoberfest time, the stations are soo crowded that boarding takes longer. Munich is planning on building a second subway route. It just does not have the money nor the space to build one. There has been discussion on building a second tunnel below the first, or on enabling the common train system for overflow by suburban trains -- by installing more signals to run more tightly packed.

agurk 1y ago
The second route is currently being built in Munich [0], with work started in 2017. I recently watched a youtube video by The B1M about rail projects in Germany that included a long section about the currently ongoing works in Munich [1] that gives a good visual overview. [0] https://db-engineering-consulting.com/en/projects/munichs-second-core-s-bahn-route/ https://db-engineering-consulting.com/en/projects/munichs-se... [1] https://www.youtube.com/watch?v=bPDQdnT-RaY https://www.youtube.com/watch?v=bPDQdnT-RaY

renewiltord 1y ago

In the US you can't do it, because the unions lobby to have two people per train and the people really like unions. EDIT: Listen, you can downvote me but it's true https://www.etany.org/statements/impeding-progress-costing-riders-opto https://www.etany.org/statements/impeding-progress-costing-r... "Facts don't care about your feelings"

bobthepanda 1y ago
New York MTA is not representative of the whole US. DC Metro for example has one driver per train. AirTrain JFK is automated with no driver.

ethagnawl 1y ago

Why are tech dudes so hung up on homelessness? Also, the reference to it was so callous and would seem to reveal a complete lack of empathy: NYC has too many homeless people; let's build a metro in Jersey City in order to make Jersey City ... more of a thing and not even attempt to address the "problem" in any substantive way. It's also a feat of mental gymnastics to put European infrastructure on a pedestal while ranting about NY's taxes and, more broadly, the US' difficulties building infrastructure.

kazinator 1y ago

Is it written in stone that a train must fit entirely into a station so that all doors face the platform and can be open simultaneously? If we think of the station as the head of a Turing machine ...

lmm 1y ago
> Is it written in stone that a train must fit entirely into a station so that all doors face the platform and can be open simultaneously? When you're building high capacity transit for dense cities, yes. You could stop the train twice in the same station, sure, but at that point you have to stop for twice as long (probably a little longer than that as your riders will get confused), so your train takes ~twice as long to get anywhere and can therefore carry ~half as many people.
bobthepanda 1y ago
It is really a safety and dwell time thing. The moment you have only some cars platforming, then people need to make sure they are in the right car, and if, say, a slow-walking elderly person is in the wrong car, then her getting into the right one to get off wastes a lot of time.
Cthulhu_ 1y ago
It's not written in stone, but if you don't, people will be moving through the train and pushing to get out sooner. Public transit is a test of patience and a study in human herd behaviour.
rsynnott 1y ago
Some metro lines have this (stations too short to fit the whole train). It is _not ideal_. Like, in some cases it's probably unavoidable, but it would not be your first choice, from a passenger ergonomics pov.

Peteragain 1y ago

Loebner (of the prize fame) patented the idea of a rollercoaster tube system. Stations on the surface, going underground and up to the next station. Saves power and reduces the curb to platform time. Just thought I'd put that out there...

bobthepanda 1y ago
Some train lines are designed like this although obviously much more gradually like the Victoria Line in London. In practice it’s pretty negligible.
Cthulhu_ 1y ago
But then you'd need stations and part of the rails on the surface, taking up valuable real estate. Versus a small entrance building. Not sure how or how much it would save power either.

curtisblaine 1y ago

Incredibile that noise, visual impact, potential disruptions to residents and property devaluing are not even mentioned in the article.

jillesvangurp 1y ago
Compared to car traffic, rail is a lot nicer. Putting it in place is indeed disruptive; just like any kind of infrastructure work. Once you have it, property values tend to go up, not down due to better transport options.
- curtisblaine 1y ago
  Not if the railway obstructs your view from the windows.

tgsovlerkhgsel 1y ago

I think this observation is undervalued: > Wait times are the second-most underrated component in making metro systems effectively faster (right after street to platform time). Street to platform time made using public transit annoying in several Asian capitals. Wait times are the main reason why I often hate traveling with public transit even in a city with one of the best public transit systems - if you aren't planning your life around the transit schedule, the wait time is essentially an unpredictable part of your travel time (and if you do plan around it, it's one more annoying thing to deal with). If you leave your doctor's office, and you have a 10 minute train home that goes every 30 minutes, then you really have a 10-40 minute train home - so for practical purposes, you essentially have a 40 minute train. Once unreliability or delays become frequent enough to start being a factor to consider, this could easily turn it into a 70 minute train. Another big factor is the time between the actual start/end of the trip and the nearest station. Even with near-zero street-to-platform time (e.g. busses/trams) and reliable, reasonably frequent public transit, once you add it all up, a bicycle often ends up being faster than even excellent public transit.

xandrius 1y ago
To be fair a bicycle is private transit but I agree with the rest.

thom 1y ago

Of course coming from the UK there is nothing that strikes horror into my heart more than being at a crowded platform waiting for a late train and it pulling up with half or quarter the carriages that you expected. Feels like a luxury to imagine a system where you’d get to tweak these variables until things work rather than trains being a force of nature.

lbriner 1y ago

I feel like this is one of those articles that claims some clever idea on paper but without experience of how this would actually work IRL but IDK if the OP has more experience than me so I will assume the best. Others have already pointed out some of the practical things that would limit what you can achieve with shorter trains like minimum headway between trains and the congestion that would occur after a delay where you would expect people to wait for maybe 10 short trains to arrive and depart before you could get on. There are other problems. The cost of the smaller trains means if e.g. 2 carriages each, then every other car is a driving vehicle with motors and control equipment. On longer trains, this could be 1 in 3 or 1 in 4. Each of these not only requires regular maintenance (so that's doubled the maintenance requirements) but also creates massive congestion issues in maintenance yards. Commonly, 1 or 2 full trains fit in each siding so getting most trains out if e.g. one is broken down is usually easy enough. Imagine having to move 3 or 4 separate smaller trains out of the way, they are not automated in the yards. Most people would be very unhappy knowing that they might be alone on a train, which is a main reason why operators are not quick to get rid of all staff. But currently, a single driver and conductor is close by for, maybe, 8 carriages. This would double if you needed a single attendent on each 2 carriage train. The signalling is very heavily designed around traditional trains with its delay after passing a signal. 4 x 2 carriage trains would utilise more signalling capacity/time than 1 x 8 carriage train. If these were all coming from the same location and needed to return, that would also need a lot more platforms so that the following trains don't block the first trains in terminal platforms. This is already a major problem at most UK terminal stations so that is largely unsurmoutable. I also heavily question the idea that station cost is largely dependent on platform length. On most surface stations, platforms are relatively easy to construct and whether they are 4 carriages or 12 carriages long still require a station building or 2, some ticket machines and CCTV etc. For elevated railways that is more likely to be true maybe. So yeah, like someone else said, we are unlikely to come up with ideas that 1000 other engineers haven't already asked, the easier problems to solve are around planning, design, legal rights for infrastructure projects etc. since these tend to eat up sometimes decades and billions of dollars.

rkachowski 1y ago

> Is this one London or Copenhagen? There’s literally no way to know! There are two passing vehicles in the background, based on the direction of movement they seem to be driving on the left. Assuming the image is not reversed this would imply London... of course, this could also be discovered by recognising literally anything else

tharmas 1y ago

Wouldn't building longer platforms (more expensive at the time) be cheaper in the long run than building an additional line to handle the excess demand that will be sure to come as a result of building it in the first place. Metro lines are built in the first place because of demand but once built demand increases also, does it not? You can run short trains with longer platforms but its more difficult the other way around.