3 ms·

The problem isn’t so much the total number of cars overall (although that’s a problem) but the number of cars _in use_ at any one time. It’s not really solvable

The problem isn’t so much the total number of cars overall (although that’s a problem) but the number of cars _in use_ at any one time. It’s not really solvable to have individual cars once you reach a certain density, you simply don’t have room for everyone. Density has lots of advantages, so it emerges nonetheless, leaving you in a bind.

martythemaniak 4y ago
Well, public transit solves this by having the vast majority of riders stand and pack very tightly during these times. No reason you can't be cramped into autonomous EVs, other than people don't want to do that. This is the issue with comparing transit to cars - the amazing capacity numbers touted by eg subways are based on great rider discomfort. The total number of cars is still a problem - they take up street parking, they require large parking structures to store during the day, etc, etc. You should think of autonomous EVs as red blood cells - constantly circulating and carrying useful loads everywhere, not sitting idle 90 percent of the time.
- potatoz2 4y ago
  Public transit will always be able to fit more people per space taken (in use and otherwise), so any problem with being packed like sardines will be multiplied tenfold in autonomous EVs. It’s 100% possible to run service often enough that people aren’t packed, even during rush hour. Some of that is by automating subways so they run every minute and closer together all day long. That’s a solved problem though, thankfully, so it’s simply a political problem not an engineering/space constraint one like autonomous individual cars.
  - martythemaniak 4y ago
    Automated subways are just autonomous cars that work in a highly constrained environment. Ie, this is that Tesla and Boring Co are attempting to build. The difference between tunnels and streets is the complexity of the environment. Let's step back and deconstruct the train. A typical LRT car has 5 segments, 50 seats and a total capacity of 250. At rush hour, this train will come every 5 minutes. What if instead, each segment came once per minute? What if instead every 6 seconds a five person vehicle rolled by? The throughput would be the same. With 5 people per vehicle instead of 250, it is highly unlikely that it needs to stop at every stop, so as long as you have a separate loading/unloading zone you can get transit capacity, seating for everyone, less waiting etc. THAT is your autonomous EVs based transit system. The reason you can't do this with drivers is because the costs of running 50 vehicles instead of one train are astronomically higher, because you need all those extra drivers. Saying it's "political" is correct, but a misdirection. Nobody is gonna pay for such a setup.
    - cycomanic 4y ago
      Have you looked at the density of 5 person cars vs a 50 person bus? The bus is certainly not 10 times as long, cars don't scale (let's not even talk about the fact that people feel much less comfortable with sitting in a car with 4 strangers than sitting on a bus with 50). Funny you mention Musks tunnel venture, there are videos of traffic jams in the Las Vegas tunnel, even though the shouldn't occur.
    - potatoz2 4y ago
      > Automated subways are just autonomous cars that work in a highly constrained environment. Ie, this is that Tesla and Boring Co are attempting to build. The difference between tunnels and streets is the complexity of the environment. No, they’re really not, just like trains aren’t just cars that operate in constrained environments. They have a number of advantages, including feasibility, max speed, efficiency. The main reason I know this is a poor comparison is that they are already in use in many countries (and they look nothing like cramped tunnels with traffic jams). > A typical LRT car has 5 segments, 50 seats and a total capacity of 250. The Paris metro has two automated lines, one built that way and one retrofitted. The retrofitted line, line 1, uses cars with capacity for 722 people https://en.wikipedia.org/wiki/MP_05 https://en.wikipedia.org/wiki/MP_05 (by comparison, an NYC train can carry around 2,000 people, they are longer). During rush hour, they have headway of 3 minutes (I’ve seen less in other subway systems, as little as 1m30, indeed it looks like line 14 has an 85 second minimum headway for safety). > What if instead every 6 seconds a five person vehicle rolled by? You’re going to struggle to embark in 6 seconds. If we solve that problem (with magical thinking or otherwise), subways are even more advantageous, since that’s where they waste tons of time! > it is highly unlikely that it needs to stop at every stop, so as long as you have a separate loading/unloading zone you can get transit capacity, seating for everyone, less waiting etc. THAT is your autonomous EVs based transit system. Turns out tons of people go to the same small set of stations, so you’re going to have a large problem embarking and disembarking in the given space. Same with time, everyone wants to move around at the same time. Again, this is a solved engineering problem, there’s no need for train-like-but-not-as-good transit autonomous individual EVs.

martythemaniak 4y ago

Well, public transit solves this by having the vast majority of riders stand and pack very tightly during these times. No reason you can't be cramped into autonomous EVs, other than people don't want to do that. This is the issue with comparing transit to cars - the amazing capacity numbers touted by eg subways are based on great rider discomfort. The total number of cars is still a problem - they take up street parking, they require large parking structures to store during the day, etc, etc. You should think of autonomous EVs as red blood cells - constantly circulating and carrying useful loads everywhere, not sitting idle 90 percent of the time.

potatoz2 4y ago
Public transit will always be able to fit more people per space taken (in use and otherwise), so any problem with being packed like sardines will be multiplied tenfold in autonomous EVs. It’s 100% possible to run service often enough that people aren’t packed, even during rush hour. Some of that is by automating subways so they run every minute and closer together all day long. That’s a solved problem though, thankfully, so it’s simply a political problem not an engineering/space constraint one like autonomous individual cars.
- martythemaniak 4y ago
  Automated subways are just autonomous cars that work in a highly constrained environment. Ie, this is that Tesla and Boring Co are attempting to build. The difference between tunnels and streets is the complexity of the environment. Let's step back and deconstruct the train. A typical LRT car has 5 segments, 50 seats and a total capacity of 250. At rush hour, this train will come every 5 minutes. What if instead, each segment came once per minute? What if instead every 6 seconds a five person vehicle rolled by? The throughput would be the same. With 5 people per vehicle instead of 250, it is highly unlikely that it needs to stop at every stop, so as long as you have a separate loading/unloading zone you can get transit capacity, seating for everyone, less waiting etc. THAT is your autonomous EVs based transit system. The reason you can't do this with drivers is because the costs of running 50 vehicles instead of one train are astronomically higher, because you need all those extra drivers. Saying it's "political" is correct, but a misdirection. Nobody is gonna pay for such a setup.
  - cycomanic 4y ago
    Have you looked at the density of 5 person cars vs a 50 person bus? The bus is certainly not 10 times as long, cars don't scale (let's not even talk about the fact that people feel much less comfortable with sitting in a car with 4 strangers than sitting on a bus with 50). Funny you mention Musks tunnel venture, there are videos of traffic jams in the Las Vegas tunnel, even though the shouldn't occur.
  - potatoz2 4y ago
    > Automated subways are just autonomous cars that work in a highly constrained environment. Ie, this is that Tesla and Boring Co are attempting to build. The difference between tunnels and streets is the complexity of the environment. No, they’re really not, just like trains aren’t just cars that operate in constrained environments. They have a number of advantages, including feasibility, max speed, efficiency. The main reason I know this is a poor comparison is that they are already in use in many countries (and they look nothing like cramped tunnels with traffic jams). > A typical LRT car has 5 segments, 50 seats and a total capacity of 250. The Paris metro has two automated lines, one built that way and one retrofitted. The retrofitted line, line 1, uses cars with capacity for 722 people https://en.wikipedia.org/wiki/MP_05 https://en.wikipedia.org/wiki/MP_05 (by comparison, an NYC train can carry around 2,000 people, they are longer). During rush hour, they have headway of 3 minutes (I’ve seen less in other subway systems, as little as 1m30, indeed it looks like line 14 has an 85 second minimum headway for safety). > What if instead every 6 seconds a five person vehicle rolled by? You’re going to struggle to embark in 6 seconds. If we solve that problem (with magical thinking or otherwise), subways are even more advantageous, since that’s where they waste tons of time! > it is highly unlikely that it needs to stop at every stop, so as long as you have a separate loading/unloading zone you can get transit capacity, seating for everyone, less waiting etc. THAT is your autonomous EVs based transit system. Turns out tons of people go to the same small set of stations, so you’re going to have a large problem embarking and disembarking in the given space. Same with time, everyone wants to move around at the same time. Again, this is a solved engineering problem, there’s no need for train-like-but-not-as-good transit autonomous individual EVs.