6 ms·

Is a 20th-century mass transit system actually preferable to robocars once the technology is mature? My guess is it's the cities like Austin, planning new trans

Is a 20th-century mass transit system actually preferable to robocars once the technology is mature? My guess is it's the cities like Austin, planning new transit systems without designing for synergies with robocars, who are failing at urban planning.

TulliusCicero 3y ago
Cars take up too much space. Relying on cars instead of mass transit means everything has to be more spread out, which makes walking and biking a lot worse.
- hansworst 3y ago
  If everyone can share a small fleet of self driving vehicles, they don’t need to take up a lot of space at all. I’m assuming you were talking about parking space; I don’t see how self driving cars would take up significantly more space than mass transit while on the road.
  - _v7gu 3y ago
    If a thousand people try to go to work at the same time, the car being driverless or not will not result in less than a thousand cars being driven, and the number of cars in the road is the biggest cause of congestion. However, a bus can carry a hundred people comfortably. Ten buses instead of a thousand cars results in much leas congestion.
    - xhkkffbf 3y ago
      Well, not exactly. The good thing is that automated, centrally booked autonomous systems can run pretty good car pools. Sure human drivers can do this but it's just not as practical. Not at all. So it's possible that those 1000 people might be served by 500, 300 or maybe even 250 autonomous cars.
  - TulliusCicero 3y ago
    > If everyone can share a small fleet of self driving vehicles They cannot. > I don’t see how self driving cars would take up significantly more space than mass transit while on the road. They would take up more space because they're cars. Cars can't get to similar efficiencies of space compared to buses unless you compared packed private cars with sparsely ridden buses. And then of course, there's trains. Perhaps someday we'll have all self driving cars that can safely coordinate and pack themselves into smaller spaces on the road, but that's decades away at a minimum, since you'd first need to get rid of all manually driven cars.
    - xnx 3y ago
      Trains are a very inefficient use of space. Trains often run nearly empty, and the tracks can only be used by trains. A road (utilized by autonomous vehicles) can be used at any time and any schedule by any vehicle, including the possibility of giving automatic intersection right of way to pedestrians, or safely sharing road space with personal transport (bikes, scooters, etc.)
imtringued 3y ago
The robocars are only a good idea if they are one seaters. Otherwise they are a waste of road space.
dymk 3y ago
Good public mass transit is absolutely superior. Waymo cars don't solve traffic, it only partly solves parking and paying a human. Having (on average) a single person take up 40 square feet of space on the road for travel is horribly inefficient. You do a few orders of magnitude better with a full train car or bus.
- George83728 3y ago
  Good public mass transit presumably involves cops kicking out the smelly homeless people, right? I don't think that would fly in most places these days though, it isn't humane. Yet it's the only way to make public transit tolerable.
  - pfsalter 3y ago
    A better idea might be to provide the homeless with a better standard of living, therefore making them nicer to be around on public transport
    - 2devnull 3y ago
      Some of them aren’t merely lacking access to resources. Mental illness is part of the picture too. Trains and busses are warm comfortable places for such, as well as the criminal element. People think of bus and subway stations as dirty and often dangerous places, not just in the USA.
    - George83728 3y ago
      You can't make them wipe.
    - xnx 3y ago
      I don't know if they're un-homed or not, but I've encountered a lot of people smoking, shouting, or making a mess with food in rail cars, making them unusable for everyone else.
- abecedarius 3y ago
  Most buses off rush hour are sparsely populated. Look up actual energy efficiency of American mass transit systems per rider mile. https://www.templetons.com/brad/transit-myth.html https://www.templetons.com/brad/transit-myth.html Re traffic: with robot-driven cars, congestion pricing would be technically easy. This is an example of not considering possibilities created by the new tech.
wolfram74 3y ago
From an energetics perspective it's incredibly hard to beat walking, biking or rails. If your occupancy on the car is reliably greater than 1, that is an improvement over single occupancy cars, but those boxes are just huge compared to a bicycle.
- abecedarius 3y ago
  Once it makes economic sense to design car models specifically for robotaxi use, small light one-passenger electric models may well become the most common type. In the graph I linked from my other reply, a one-person E.V. like this beat all of the transit systems and came in second only to an electric scooter/trike.
  - pfsalter 3y ago
    Still more cost efficient to run a single bus than separate vehicles, just in maintenance alone. Also we already have buses, these single occupation EVs that still have enough space for a decent battery size don't exist.
    - xnx 3y ago
      These seems reasonable, but I don't think the math holds up. A 2016 study (http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20for%20NYC%20Transit%20by%20J%20Aber%20Columbia%20University%20-%20May%202016.pdf http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20...) showed the lifetime cost (including maintenance) of a bus for its 12 year useful lifespan to be $1.4 million. Without even doing the inflation adjustment, that could buy at least 12 electric vehicles. Those 12 vehicles could be much more efficient even running on a single fixed bus route (i.e. more frequent schedule), or (more likely) operating like taxis by taking people to and from exactly where they want to go.
- HALtheWise 3y ago
  I spouted this line for a long time, but was recently corrected by commenters pointing out that 2-3 occupancy electric cars actually beat the vast majority of subways and trains in practice, because you don't need to accelerate and decelerate every passenger at every possible stop. Cars are designed to be remarkably aerodynamically efficient, especially compared to motorcycles or bicycles, and an electric battery+motor is much more efficient at producing power than your muscles. Delivering on this requires some sort of "Uber Pool" like algorithm to put a few people together in a vehicle, but doesn't require large busses.

TulliusCicero 3y ago

Cars take up too much space. Relying on cars instead of mass transit means everything has to be more spread out, which makes walking and biking a lot worse.

hansworst 3y ago
If everyone can share a small fleet of self driving vehicles, they don’t need to take up a lot of space at all. I’m assuming you were talking about parking space; I don’t see how self driving cars would take up significantly more space than mass transit while on the road.
- _v7gu 3y ago
  If a thousand people try to go to work at the same time, the car being driverless or not will not result in less than a thousand cars being driven, and the number of cars in the road is the biggest cause of congestion. However, a bus can carry a hundred people comfortably. Ten buses instead of a thousand cars results in much leas congestion.
  - xhkkffbf 3y ago
    Well, not exactly. The good thing is that automated, centrally booked autonomous systems can run pretty good car pools. Sure human drivers can do this but it's just not as practical. Not at all. So it's possible that those 1000 people might be served by 500, 300 or maybe even 250 autonomous cars.
- TulliusCicero 3y ago
  > If everyone can share a small fleet of self driving vehicles They cannot. > I don’t see how self driving cars would take up significantly more space than mass transit while on the road. They would take up more space because they're cars. Cars can't get to similar efficiencies of space compared to buses unless you compared packed private cars with sparsely ridden buses. And then of course, there's trains. Perhaps someday we'll have all self driving cars that can safely coordinate and pack themselves into smaller spaces on the road, but that's decades away at a minimum, since you'd first need to get rid of all manually driven cars.
  - xnx 3y ago
    Trains are a very inefficient use of space. Trains often run nearly empty, and the tracks can only be used by trains. A road (utilized by autonomous vehicles) can be used at any time and any schedule by any vehicle, including the possibility of giving automatic intersection right of way to pedestrians, or safely sharing road space with personal transport (bikes, scooters, etc.)

imtringued 3y ago

The robocars are only a good idea if they are one seaters. Otherwise they are a waste of road space.

dymk 3y ago

Good public mass transit is absolutely superior. Waymo cars don't solve traffic, it only partly solves parking and paying a human. Having (on average) a single person take up 40 square feet of space on the road for travel is horribly inefficient. You do a few orders of magnitude better with a full train car or bus.

George83728 3y ago
Good public mass transit presumably involves cops kicking out the smelly homeless people, right? I don't think that would fly in most places these days though, it isn't humane. Yet it's the only way to make public transit tolerable.
- pfsalter 3y ago
  A better idea might be to provide the homeless with a better standard of living, therefore making them nicer to be around on public transport
  - 2devnull 3y ago
    Some of them aren’t merely lacking access to resources. Mental illness is part of the picture too. Trains and busses are warm comfortable places for such, as well as the criminal element. People think of bus and subway stations as dirty and often dangerous places, not just in the USA.
  - George83728 3y ago
    You can't make them wipe.
  - xnx 3y ago
    I don't know if they're un-homed or not, but I've encountered a lot of people smoking, shouting, or making a mess with food in rail cars, making them unusable for everyone else.
abecedarius 3y ago
Most buses off rush hour are sparsely populated. Look up actual energy efficiency of American mass transit systems per rider mile. https://www.templetons.com/brad/transit-myth.html https://www.templetons.com/brad/transit-myth.html Re traffic: with robot-driven cars, congestion pricing would be technically easy. This is an example of not considering possibilities created by the new tech.

wolfram74 3y ago

From an energetics perspective it's incredibly hard to beat walking, biking or rails. If your occupancy on the car is reliably greater than 1, that is an improvement over single occupancy cars, but those boxes are just huge compared to a bicycle.

abecedarius 3y ago
Once it makes economic sense to design car models specifically for robotaxi use, small light one-passenger electric models may well become the most common type. In the graph I linked from my other reply, a one-person E.V. like this beat all of the transit systems and came in second only to an electric scooter/trike.
- pfsalter 3y ago
  Still more cost efficient to run a single bus than separate vehicles, just in maintenance alone. Also we already have buses, these single occupation EVs that still have enough space for a decent battery size don't exist.
  - xnx 3y ago
    These seems reasonable, but I don't think the math holds up. A 2016 study (http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20for%20NYC%20Transit%20by%20J%20Aber%20Columbia%20University%20-%20May%202016.pdf http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20...) showed the lifetime cost (including maintenance) of a bus for its 12 year useful lifespan to be $1.4 million. Without even doing the inflation adjustment, that could buy at least 12 electric vehicles. Those 12 vehicles could be much more efficient even running on a single fixed bus route (i.e. more frequent schedule), or (more likely) operating like taxis by taking people to and from exactly where they want to go.
HALtheWise 3y ago
I spouted this line for a long time, but was recently corrected by commenters pointing out that 2-3 occupancy electric cars actually beat the vast majority of subways and trains in practice, because you don't need to accelerate and decelerate every passenger at every possible stop. Cars are designed to be remarkably aerodynamically efficient, especially compared to motorcycles or bicycles, and an electric battery+motor is much more efficient at producing power than your muscles. Delivering on this requires some sort of "Uber Pool" like algorithm to put a few people together in a vehicle, but doesn't require large busses.