4 ms·

cars are not a replacement for trains, period, full stop. autonomous operation does not change the fundamental math. a single BART train car carries 50 people

cars are not a replacement for trains, period, full stop. autonomous operation does not change the fundamental math. a single BART train car carries 50 people seated, up to 200 people when packed nuts-to-butts. the longest trains are 10 cars [0]. so at rush hour, you'd expect 500-2000 people per train. say we replace one single train with autonomous cars. that means the roads surrounding the subway station now have an additional 500-2000 cars, beyond the existing traffic of rush hour. and they're all trying to navigate to a curb lane so they can pick up or drop off their passenger safely. if your trains are running 10 minute headways, that means in order to compete, those 500-2000 autonomous cars have 10 minutes to clear the area around the station, and at the same time another group of 500-2000 cars needs to come in, in order to pick up or drop off the next trainload. the math simply doesn't work. even if a genie granted you three wishes and you used all of them on having cars that are perfect, absolutely bug-free, incredibly smart, 100% autonomous in all driving conditions, there is no way to match the density of people movement that trains allow. 0: https://www.bart.gov/about/history/cars https://www.bart.gov/about/history/cars

lawrenceyan 4y ago
The US isn’t really dense enough to support trains except in major population centers. Self-driving vehicles scale to all areas. I think it’s important not to forget the suburban / rural places we have. There’s a lot of value there.
- evil-olive 4y ago
  your original statement was that self-driving cars would replace systems like BART that operate in dense urban areas. now it seems like you're moving the goalposts to talk about rural areas. > except in major population centers 80% of the US population lives in what the Census considers an urban area [0] for the remaining 20% in rural areas...I don't think anyone would argue that subway trains are the ideal mode of transport for them. but at the same time, I don't think the "shared fleet of autonomous robo-taxis" model is the right fit for rural areas either. if I lived in a rural area, I'd want to have a vehicle I owned in my driveway, ready to go whenever I needed it. it may have some autonomous features, but I would have no interest in any of the "have your car make money while you sleep" [1] programs that autonomous car companies have proposed. if your concern is promoting transportation methods that are useful and effective across rural, suburban, and urban areas, the best example of that that I'm aware of is the humble bicycle. are you in favor of improving bicycle infrastructure as well, such as by building more protected bike lanes, tax credits for e-bikes, etc? that is in many ways not as "sexy" as autonomous cars, but that's because it's a boring, proven technology that could easily be implemented in a wide variety of jurisdictions. 0: https://www.census.gov/programs-surveys/geography/guidance/geo-areas/urban-rural/ua-facts.html https://www.census.gov/programs-surveys/geography/guidance/g... 1: https://futurism.com/the-byte/ride-hailing-tesla-elon-musk https://futurism.com/the-byte/ride-hailing-tesla-elon-musk
  - bombcar 4y ago
    The "census urban" definition is almost worthless; it considers many small towns in the United States to be urban. https://www2.census.gov/geo/pdfs/reference/GARM/Ch12GARM.pdf https://www2.census.gov/geo/pdfs/reference/GARM/Ch12GARM.pdf According to the census, I'm in an urban area. And it is true, I can walk to a grocery store, but there will likely not be much transit here at all, since the population total is about 8000.
    - runarberg 4y ago
      A town of 8000 definitely warrants a bus line or two. In addition to inter city buses to nearby towns and cities. I live in what I consider a rural American town, 10,000 people spread around 200 km² (but US census still considers it urban (!) so you are right about that) and still we get regular bus service from 2 lines and a couple of ferry lines to nearby cities. But to raise the point of your parent home, we do have a car in our driveway ready for our convenience, but a bicycle is actually way handy (especially when coming home from the bar) and then the bus is actually very well used, and has been increasing in frequency over the past decade. It is simply way more convenient to ride the bus to the ferry then drive during commuter hours.
      - bombcar 4y ago
        Yeah, I find that transit in these smaller towns really depends on the towns around (you have a ferry to get to, we have various other smallish towns each about 15 - 20 minutes away). The town itself is very bikeable, walkable even (an hour or so will get you literally from any point to any point), but connections to other towns might be interesting (the only thing we have is a public ride service for elderly/disabled, though others can use it without the subsidy) - it's a glorified taxi.
- midoridensha 4y ago
  We're not talking about the entire US, we're talking about SanFran, which is very much an urban area.
  - lawrenceyan 4y ago
    The Bay Area is actually pretty suburban. It’s decently hard to get by without a car.

lawrenceyan 4y ago

The US isn’t really dense enough to support trains except in major population centers. Self-driving vehicles scale to all areas. I think it’s important not to forget the suburban / rural places we have. There’s a lot of value there.

evil-olive 4y ago
your original statement was that self-driving cars would replace systems like BART that operate in dense urban areas. now it seems like you're moving the goalposts to talk about rural areas. > except in major population centers 80% of the US population lives in what the Census considers an urban area [0] for the remaining 20% in rural areas...I don't think anyone would argue that subway trains are the ideal mode of transport for them. but at the same time, I don't think the "shared fleet of autonomous robo-taxis" model is the right fit for rural areas either. if I lived in a rural area, I'd want to have a vehicle I owned in my driveway, ready to go whenever I needed it. it may have some autonomous features, but I would have no interest in any of the "have your car make money while you sleep" [1] programs that autonomous car companies have proposed. if your concern is promoting transportation methods that are useful and effective across rural, suburban, and urban areas, the best example of that that I'm aware of is the humble bicycle. are you in favor of improving bicycle infrastructure as well, such as by building more protected bike lanes, tax credits for e-bikes, etc? that is in many ways not as "sexy" as autonomous cars, but that's because it's a boring, proven technology that could easily be implemented in a wide variety of jurisdictions. 0: https://www.census.gov/programs-surveys/geography/guidance/geo-areas/urban-rural/ua-facts.html https://www.census.gov/programs-surveys/geography/guidance/g... 1: https://futurism.com/the-byte/ride-hailing-tesla-elon-musk https://futurism.com/the-byte/ride-hailing-tesla-elon-musk
- bombcar 4y ago
  The "census urban" definition is almost worthless; it considers many small towns in the United States to be urban. https://www2.census.gov/geo/pdfs/reference/GARM/Ch12GARM.pdf https://www2.census.gov/geo/pdfs/reference/GARM/Ch12GARM.pdf According to the census, I'm in an urban area. And it is true, I can walk to a grocery store, but there will likely not be much transit here at all, since the population total is about 8000.
  - runarberg 4y ago
    A town of 8000 definitely warrants a bus line or two. In addition to inter city buses to nearby towns and cities. I live in what I consider a rural American town, 10,000 people spread around 200 km² (but US census still considers it urban (!) so you are right about that) and still we get regular bus service from 2 lines and a couple of ferry lines to nearby cities. But to raise the point of your parent home, we do have a car in our driveway ready for our convenience, but a bicycle is actually way handy (especially when coming home from the bar) and then the bus is actually very well used, and has been increasing in frequency over the past decade. It is simply way more convenient to ride the bus to the ferry then drive during commuter hours.
    - bombcar 4y ago
      Yeah, I find that transit in these smaller towns really depends on the towns around (you have a ferry to get to, we have various other smallish towns each about 15 - 20 minutes away). The town itself is very bikeable, walkable even (an hour or so will get you literally from any point to any point), but connections to other towns might be interesting (the only thing we have is a public ride service for elderly/disabled, though others can use it without the subsidy) - it's a glorified taxi.
midoridensha 4y ago
We're not talking about the entire US, we're talking about SanFran, which is very much an urban area.
- lawrenceyan 4y ago
  The Bay Area is actually pretty suburban. It’s decently hard to get by without a car.