5 ms·

With mass carsharing, the number of cars should fall so this should be less of a concern. I agree though - if your cities are already gridlocked, this won't ma

by jnty 10y ago

With mass carsharing, the number of cars should fall so this should be less of a concern. I agree though - if your cities are already gridlocked, this won't make them somehow less gridlocked. You still need mass transit, cycling and walking no matter who's driving the cars.

cesis 10y ago
There's concept called "platooning". If distances between cars could be reduced, road passenger density could be improved dramatically.
JoeAltmaier 10y ago
The number of cars is irrelevant to congestion. The number on the road is important. And with car-sharing there are exactly the same number of useful car trips (people getting to work or home) plus the deadheading. Its strictly (much) worse.
halomru 10y ago
>if your cities are already gridlocked, this won't make them somehow less gridlocked I disagree. Human drivers use roads very inefficiently: they overreact, have high latency and drive overly selfish. Computers can drive cars closer together, can maintain higher speed with the same safety margins and without causing traffic jams by overbreaking, and they have no problems obeying traffic laws (and thus won't cause a literal gridlock). The only reason why self-driving cars won't notably reduce road utilisation is because of induced demand
- JoeAltmaier 10y ago
  And because with car-sharing it doubles the number of car-miles. Because, deadheading (driving to the next pickup point).
  - halomru 10y ago
    It only doubles the car miles if there's nobody nearby to pick up. That would mean that most people are headed in a similar direction (e.g. all from suburbs towards city). But if all head in the same direction, the lane for return traffic has virtually no humans, and car-miles on it don't matter. So either the traffic patterns allow pickup to be optimized to do much better than doubling the car-miles, or traffic patterns are so that it doesn't matter. (of course that's overly simplistic, but I don't see how it's a less valid simplification than yours)
    - VLM 10y ago
      "virtually no humans" Something interesting to think about is logistics optimization. I have nothing against the big brown trucks but it should somehow be possible to haul my amazon packages from distribution center in the city by the railroad tracks to the burbs. Or distro center to distro center package movement.
    - JoeAltmaier 10y ago
      Of course doubling is a simplification. Even one more car in the congested direction makes auto-driving car-sharing strictly worse for congestion. The question is how much worse. In Silicon Valley for instance, where everybody lives everywhere and works somewhere else, its a mesh of commute traffic and doubling may be a good estimate. The important case of commuting toward the city is interesting. Car-sharing breaks completely there - everybody starts work at about the same time (commute traffic confirms this). So we'll need as many shared cars as we already have. No savings at all. Any savings comes down to off-commute traffic. Its a second-order effect. Maybe even too insignificant to bother with the complexity of sharing.
      - marcosdumay 10y ago
        It adds almost no cars in the congested direction. That's because there are already many cars going there. If people are going from everywhere to everywhere, there will be almost no extra cars.
        10y ago

by jnty 10y ago

cesis 10y ago

There's concept called "platooning". If distances between cars could be reduced, road passenger density could be improved dramatically.

JoeAltmaier 10y ago

The number of cars is irrelevant to congestion. The number on the road is important. And with car-sharing there are exactly the same number of useful car trips (people getting to work or home) plus the deadheading. Its strictly (much) worse.

halomru 10y ago

>if your cities are already gridlocked, this won't make them somehow less gridlocked I disagree. Human drivers use roads very inefficiently: they overreact, have high latency and drive overly selfish. Computers can drive cars closer together, can maintain higher speed with the same safety margins and without causing traffic jams by overbreaking, and they have no problems obeying traffic laws (and thus won't cause a literal gridlock). The only reason why self-driving cars won't notably reduce road utilisation is because of induced demand

JoeAltmaier 10y ago
And because with car-sharing it doubles the number of car-miles. Because, deadheading (driving to the next pickup point).
- halomru 10y ago
  It only doubles the car miles if there's nobody nearby to pick up. That would mean that most people are headed in a similar direction (e.g. all from suburbs towards city). But if all head in the same direction, the lane for return traffic has virtually no humans, and car-miles on it don't matter. So either the traffic patterns allow pickup to be optimized to do much better than doubling the car-miles, or traffic patterns are so that it doesn't matter. (of course that's overly simplistic, but I don't see how it's a less valid simplification than yours)
  - VLM 10y ago
    "virtually no humans" Something interesting to think about is logistics optimization. I have nothing against the big brown trucks but it should somehow be possible to haul my amazon packages from distribution center in the city by the railroad tracks to the burbs. Or distro center to distro center package movement.
  - JoeAltmaier 10y ago
    Of course doubling is a simplification. Even one more car in the congested direction makes auto-driving car-sharing strictly worse for congestion. The question is how much worse. In Silicon Valley for instance, where everybody lives everywhere and works somewhere else, its a mesh of commute traffic and doubling may be a good estimate. The important case of commuting toward the city is interesting. Car-sharing breaks completely there - everybody starts work at about the same time (commute traffic confirms this). So we'll need as many shared cars as we already have. No savings at all. Any savings comes down to off-commute traffic. Its a second-order effect. Maybe even too insignificant to bother with the complexity of sharing.
    - marcosdumay 10y ago
      It adds almost no cars in the congested direction. That's because there are already many cars going there. If people are going from everywhere to everywhere, there will be almost no extra cars.
      - 10y ago