I'd say instead that it means "A to B faster". What do I care how many cars there are? If I get there faster, there's less traffic. Autonomous cars have great potential to reduce traffic by driving together, closer to each other than people can do safely."Reduce traffic" means "fewer cars on the road."
What you say doesn't matter. The actual outcome of autonomous fleet driving is "more cars per road." With a bunch of autonomous drivers and no human ones, the driving distance can go down (until things go wrong - more discussion below) which means the effective speed can go up. Get a human in there, though, and it all goes wrong. Suddenly you've got a freeway full of tailgaters. Many of the glorious promises of "autonomous driving" presume that "human driving" is illegal. That's an entirely different discussion.
If you define "more traffic" as "more cars on the road", sure. That's a shitty definition of traffic, though.
Regardless of your opinions on the matter, it's the accepted definition.
In your link, it says traffic congestion IS typically measured by delays. See the "classification" section.
That's because it's independent of lane width. Check again. The actual metric depends on follow distance and stability of flow - automation, tying this all back to the fork that it all split off of, would decrease follow distance and increase stability of flow (effectively nuking the scale). The money quote is right here: Automation would increase the use of road networks. That's the point.Traffic congestion is a condition on road networks that occurs as use increases
There's an implied "all else being equal" there, though. All else isn't equal. You want to say that automation will increase congestion, and you're willing to assume the "more cars", but not the "tighter grouping" aspect.
I'm not trying to say one will outweigh the other (I couldn't begin to guess), but it seems to me you are dismissing the latter out of hand because it doesn't match your argument.Traffic congestion is a condition on road networks that occurs as use increases
You misunderstand my argument. I'm saying that in order for automated cars to "decrease traffic" (by your definition), "tighter grouping" is necessary. I'm further saying that with non-automated cars in traffic, the grouping is already maxed as it is. It's a lowest-common-denominator problem - if 80% of your cars are automated and can keep a follow distance of 50 feet at 70mph but 20% are piloted and require a follow distance of 250 feet at 70mph, your fleet pulls a lot closer to the wide spacing than the close. The way it actually gets handled is gonna be interesting to see; it'll depend on a lot of variables. "A to B faster" remains to be seen, and as we're now both saying, dependent on decreased following distance. Decreased following distance is dependent on pilotless saturation. Either way, the mechanism is "more cars with less road" and that's "traffic."
I'm not trying to be argumentative; I agree with most everything you've said here. I should also say that as an experienced embedded programmer, this whole idea scares the crap out of me. I'd still like to see it happen, but colour me skeptical.I'm further saying that with non-automated cars in traffic, the grouping is already maxed as it is.
I don't understand.
your fleet pulls a lot closer to the wide spacing than the close
This either. I'm assuming the automated cars will bunch up together and drift off each other. That right there reduces congestion, and the greater the percentage of automated cars, the more reduction (compared to a field of 100% human drivers).
Correct. But riddle me this: when you're driving down the freeway, do you maintain a safe following distance? Or do you tailgate? With a pilotless vehicle, the "safe following distance" is the "tailgating" of a piloted vehicle. Works great when you've got pilotless vehicles following other pilotless vehicles. Kind of comes apart at the seams when you've got a piloted vehicle following a pilotless vehicle. Consider the implications. I head out onto the 405. I'm the only person driving in a sea of Google Priuses. My safe following distance is the two second rule - at 70mph, that's 205 ft. call it 10 car lengths. The Google Priuses, however, are automated. Are infrared, laser and radar. Are running 8 cores at 3.5GHz. They're rawkin' a quarter-second rule, but for safety's sake, they're going for a half second. That's 50 feet. From a "traffic" standpoint, we just got 4 times as many cars on the road. So that's pretty dope. But here I come! The first thing that happens is that Google has no idea who I am or what I'm going to do. So anything that senses me is going to go "OH SHIT HUMAN" and make a little bubble around me. If it's clever, it'll give me the space to merge, to change lanes, to pass, to do whatever I need in 'human' spacing. So for the area directly around me, my density goes down to what it was originally. But Google has to do that for any vehicle that isn't part of its network. It has to presume that an object it cannot control is a lowest-common-denominator vehicle. It can tailgate the hell out of me... but I'll bet it doesn't. I'll bet that ends up being against the law, same as if Google were a person. Here's where the math gets interesting. I have no idea at what mix the traffic becomes dominated by "human accommodation." Your network also has to deal with merging "human bubbles" even where it is efficient. Throw a little snow on the road and all of a sudden these people that have been blissed out, stoned, and playing Words with Friends for the past 20 minutes are suddenly at the wheel of a vehicle on an icy road. And all this presumes that the system works as designed, works as intended. Google has FUCKED the 405 for the past few weeks because they started integrating Waze into their routing. Which means anybody using Google Maps during rush hour gets "In 600 feet take the off-ramp" even if they're 4 lanes over. It ain't pretty. Plenty of people are stupid enough to try.I'm assuming the automated cars will bunch up together and drift off each other.
I get all that. Congestion still goes down. Whenever two google-cars pair up and become (effectively) one longer car, it's a little less congestion. You might argue that it's not enough, but it's surely something. Those google-cars that see you coming on to the 405 - are you assuming they will give you more room than humans would? Because they are responsible drivers? I suppose that might negate some of the congestion gains, but I'm hard-pressed to see any other way congestion could be anything but improved with google-cars.
I would argue that it's an exponential growth curve and the tail is going to be very long. I would further argue that as more people get used to not having to drive, the more things are going to suck when they're forced to in a rainstorm. To be clear: I don't think driverless cars are a bad idea. I do think that their benefits are oversold, their timeline is overly optimistic, and as panaceas for reducing traffic they suck ass compared to viable mass transit.You might argue that it's not enough, but it's surely something.
Fair enough, and agreed on all points.
I think it would be a very bad idea to have driverless cars that people can take over from and drive, ever, for just those reasons you mention. Autonomous vehicles ought not to allow a human driver; just my opinion. "Smart cruise control" - no thanks. Recipe for disaster.
Sorry - I really should be talking about congestion, not traffic. My bad.