3 ms·

It would need to slow down due to traffic. I'm totally sympathetic to the cause. But I also agree with the author, we can't ignore the fundamental of transit,

It would need to slow down due to traffic. I'm totally sympathetic to the cause. But I also agree with the author, we can't ignore the fundamental of transit, or we will just build something even worse. Assuming everyone could have a single passenger autonomous vehicle, ideally as small as possible, while still spacious enough to satisfy our elitism desires. And it were to pick you up and drop you off at your exact destinations. How would traffic jams not be as huge an issue as they are today? If not more, assuming you got rid of mass transit? Are we suggesting to massively increase the size of roads, or tunnel roads and layer them, but still, there's gonna be point of contention within the network, causing traffic again. I feel that's pretty much the author's claim. That unless a radical idea to this problem is figured out, which I guess hasn't, then its just foolish to think we can all be picked up and dropped off wherever, riding solo at that. It won't scale. That's why its elites projection. From the problem itself, you can show it can only work for a small number of individual. But if you are that individual, you might think, I can just give this to everyone else, and problem will be solved. Forgetting the main purpose of why mass transit exists in the first place. Which isn't affordability of a car. But scale of efficiently moving large number of people around in limited space.

nostrademons 8y ago
You're still assuming a human driver. Most of the carrying capacity of roads is dictated by human reaction times. A human takes 150-250ms to perceive a change in the environment and react to it. A car travels about 15 feet/second for every 10 mph of speed. Hence the rule of thumb to stay one car length apart for every 10 mph of speed; that gives you about a second of reaction time, a safety factor of 4. It would be suicidal to drive one foot away from the car in front of you at 60 mph, as a human. It takes a computer maybe 10ms to detect and react to a change in front of it, and that's assuming fancy computer-vision algorithms (it's much easier if you just put a laser beacon on all vehicles that rapidly flashes an encoded representation of the vehicle's ID, velocity, and acceleration). And computers are much better at measuring velocity, acceleration, and position with the help of a LIDAR or doppler radar. In 10ms, the vehicle will move roughly 2 inches per 10mph of speed. Suddenly it's reasonable to drive 60mph with 2-3 feet of separation between vehicles. At that range, though, you might as well just put down a hook and latch the vehicles together. And I think that's what the OP means by cars <=> buses <=> trams <=> trains existing on a continuum, and autonomous vehicles making this clear. We'll likely get something that works like a scooter for last-mile transit, and works like a train for long-distance trips. As it enters a main road, the computers will automatically adjust speed so that they can "dock", and we'll fit an order of magnitude more vehicles onto the road.
- didibus 8y ago
  Such an idea sounds like it would be pretty easy to simulate, and know its capacity. I'm still not convinced until I see data. You're optimizing the road network to its maximum, but that might still not be enough to prevent traffic given a point to point system. But, maybe it is, I think we'd need to see data. Also, I'm not sure all the assumptions make sense, I'd be surprised if safety was all about reaction time, there seems to be an upper cap here, where even if you had instantaneous reaction times, you still need a good distance between the vehicles to avoid a collision.

nostrademons 8y ago

You're still assuming a human driver. Most of the carrying capacity of roads is dictated by human reaction times. A human takes 150-250ms to perceive a change in the environment and react to it. A car travels about 15 feet/second for every 10 mph of speed. Hence the rule of thumb to stay one car length apart for every 10 mph of speed; that gives you about a second of reaction time, a safety factor of 4. It would be suicidal to drive one foot away from the car in front of you at 60 mph, as a human. It takes a computer maybe 10ms to detect and react to a change in front of it, and that's assuming fancy computer-vision algorithms (it's much easier if you just put a laser beacon on all vehicles that rapidly flashes an encoded representation of the vehicle's ID, velocity, and acceleration). And computers are much better at measuring velocity, acceleration, and position with the help of a LIDAR or doppler radar. In 10ms, the vehicle will move roughly 2 inches per 10mph of speed. Suddenly it's reasonable to drive 60mph with 2-3 feet of separation between vehicles. At that range, though, you might as well just put down a hook and latch the vehicles together. And I think that's what the OP means by cars <=> buses <=> trams <=> trains existing on a continuum, and autonomous vehicles making this clear. We'll likely get something that works like a scooter for last-mile transit, and works like a train for long-distance trips. As it enters a main road, the computers will automatically adjust speed so that they can "dock", and we'll fit an order of magnitude more vehicles onto the road.

didibus 8y ago
Such an idea sounds like it would be pretty easy to simulate, and know its capacity. I'm still not convinced until I see data. You're optimizing the road network to its maximum, but that might still not be enough to prevent traffic given a point to point system. But, maybe it is, I think we'd need to see data. Also, I'm not sure all the assumptions make sense, I'd be surprised if safety was all about reaction time, there seems to be an upper cap here, where even if you had instantaneous reaction times, you still need a good distance between the vehicles to avoid a collision.