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Can a single car break a traffic jam?

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Re: Can a single car break a traffic jam?

#41

Post by darpa_escapee »

ctdonath wrote: post #7
revscat wrote: post #3

This is almost a perfect metaphor for the failings of capitalism, or at they very least the notion that the singular pursuit of selfish greed can lead to ideal outcomes. The selfish need for individual drivers to go as fast as they can leads to a collective failure, here in the form of a traffic jam.

Capitalists are generally smart enough to forego immediate gain in favor of substandard greater gains under different conditions. Rather than drive as fast as I can in Atlanta's 8AM rush hour (and get nowhere fast in the ensuing jam), I leave for work before 6AM (with half the drive time).

On the other hand, quarterly profits.

Re: Can a single car break a traffic jam?

#42

Post by maxerickson »

SilasX wrote: post #40
maxerickson wrote: post #34

Earlier quoted context omitted.

Tariffs. If people want access to a congested zone, charge them for it. Dynamically adjust the tariff based on the level of congestion. Of course people hate this and wail that it isn't fair, but it is among the more fair solutions to the immediate problem and inflicting traffic jams is probably not a good way to address economic inequality.

Agree. Tolls (assuming they means the same thing as tariffs) can also create the critical mass necessary for commuter bus lines to work, thereby allowing people to spend only a little more than they do now on commuting but get there faster since the roads are cleared. (The per person effective toll would be lower on a bus, even if they are charged by size.) But they would have to be much higher than in most proposals…

Yes, toll is the better word. For a system with dynamic pricing, once you have a critical mass of vehicles with some sort of system to notify the drivers, you can even set the toll experimentally.

Re: Can a single car break a traffic jam?

#43

Post by Retric »

cortesoft wrote: post #14

This sort of traffic jam dissipation is only applicable to phantom traffic jams. Here in Los Angeles, traffic jams are caused by too many cars being on the road. At some point, every available square foot of roadway is filled with a car. AI can help limit the amount of extra space taken up by air, but that will only moderately increase the number of cars that it will take before traffic hits. That number of cars will…

Yea, I remember getting stuck in a huge traffic jam and feeling dumb for driving on 66 at rush hour. Until, I remembered it was Saturday. In northern VA traffic is often bad at from around 5AM to 10PM. But, we can have traffic jams at any time day or night 7 days a week.

Granted, bad night time traffic is often aided by construction. But, that does not help when your parked on a freeway at 3AM.

Re: Can a single car break a traffic jam?

#44

Post by arprocter »

serge2k wrote: post #38
elchief wrote: post #35

The trick is to leave enough room in front of you so you don't have to jam the brakes, but not enough room that some fucker will pull in front of you. I also try to jump into the left lane at an intersection stop, if there's no left turner, to let people turn right

> not enough room that some fucker will pull in front of you. why does it matter, most of the time?

Because then you have to slow down to open a new gap.

And then once you do some other genius pulls into the space.

Repeat for entirety of journey.

Re: Can a single car break a traffic jam?

#45

Post by wlesieutre »

jerf wrote: post #21
revscat wrote: post #3

This is almost a perfect metaphor for the failings of capitalism, or at they very least the notion that the singular pursuit of selfish greed can lead to ideal outcomes. The selfish need for individual drivers to go as fast as they can leads to a collective failure, here in the form of a traffic jam.

You don't need "selfishness" to create traffic jams. You need only "latency in response"; if you response less than instantaneously to the car in front of you slowing down, and you response less than instantaneously to the car in front of you speeding up (especially if you accelerate even a bit conservatively, let alone late), you very quickly get amplifying waves. Your post, if we're going to trade snarky political…

You shouldn't even want to accelerate immediately at the same rate as the car in front of you, unless you're very optimistic about 1) having instant reflexes on the brake pedal even though your foot is currently on the gas pedal, and 2) your car's stopping distance being exactly the same as every other vehicle.

Having a time delay on your acceleration means that your following distance will increase as speed does, which is the safe behavior. I've had plenty of times when I thought "woo, we're accelerating, it's the end of the traffic jam!" and then had to hit the brakes when we came around a turn into more traffic. Traffic might be reduced if we all rode everyone's bumper all time time and accelerated as a single unit, but that doesn't mean we can actually do that without tons of collisions.

Re: Can a single car break a traffic jam?

#46

Post by arprocter »

noonshine wrote: post #12

I have adaptive cruise control in my Subaru Legacy and I have often wondered what will happen when more people have ACC. Or even if I were following another car exactly like mine - would the lag time grow exponentially with more intense stop/go or would it even out? Or does it depend on how well the car implements it?

There was an Acura ad recently which said the car would change your route if it knew there was a jam ahead.

I thought 'what happens if the ad is so successful everyone buys that Acura?'

Re: Can a single car break a traffic jam?

#47

Post by talldan »

When driving I've also noticed another phenomenon. When reaching the crest of a hill there's an optical illusion that cars are bunched together. From this viewpoint the driver can see more of the road and vehicles ahead. My theory is that this causes a momentary shock or panic, and it often causes drivers to slam on the brakes, causing ripples of braking behind them.

Re: Can a single car break a traffic jam?

#48

Post by jerf »

wlesieutre wrote: post #45
jerf wrote: post #21

Earlier quoted context omitted.

You don't need "selfishness" to create traffic jams. You need only "latency in response"; if you response less than instantaneously to the car in front of you slowing down, and you response less than instantaneously to the car in front of you speeding up (especially if you accelerate even a bit conservatively, let alone late), you very quickly get amplifying waves. Your post, if we're going to trade snarky political…

You shouldn't even want to accelerate immediately at the same rate as the car in front of you, unless you're very optimistic about 1) having instant reflexes on the brake pedal even though your foot is currently on the gas pedal, and 2) your car's stopping distance being exactly the same as every other vehicle. Having a time delay on your acceleration means that your following distance will increase as speed does, wh…

"You shouldn't even want to accelerate immediately at the same rate as the car in front of you,... but that doesn't mean we can actually do that without tons of collisions."

That is correct. Therefore, safe driving will actually create traffic waves. It seems unlikely we'd actually want the regulations that would prevent this sort of wave!

Re: Can a single car break a traffic jam?

#49

Post by arprocter »

I wonder how much of this is mitigated by good lane discipline?

My SO actually got pulled over the other day (or at least that's what the cop used as an excuse) for driving in a passing lane when not passing anything. I said I was glad because it's a terrible habit - every lane ending up going the same speed as the slowest driver

Re: Can a single car break a traffic jam?

#50

Post by labster »

bagacrap wrote: post #30
logn wrote: post #15

I often try the technique of leaving lots of space and going at a slower, steady pace. One problem is that everyone re-routes around you, and you induce road rage and traffic weaving. The other problem is that unless it's a straight stretch of road, you have no idea what speed is slow enough.

The other problem is that this isn't scalable. Imagine a traffic jam that stretches for miles. Now imagine that same jam where everyone has left an extra three car lengths in front of them. You're suddenly using a lot more road per car. Tailgating actually seems like the most efficient use of space to me, provided you tailgate effectively (don't yo-yo).

You're proposing changing the traffic pattern to look like a liquid instead of a gas. Guess which state has a higher viscosity?

If we all computerized cars that introduced 0 stochastic motion, this might work. But if one deer gets a dumb idea you're going to have a multi-kilometer pileup.

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