Can a single car break a traffic jam?
bbc.com
bbc.com
If ever there is a traffic jam on the highway, you will see the big rigs consistently leaving hundreds of feet of space in front of them.
They also seem to concentrate in the center lanes of the highway for reasons I haven't figured out yet.
Most likely because if a lane is closed it will be an edge lane. Also, if you're on a 3 lane road and two lanes are closed, you only have to make one lane change to keep going.
> ding ding ding ding! We have a winner.
I cannot speak for others, but, at least to me, this reads as extremely condescending: it makes it sound like other commenters are basically picking arguments at random and you are the only one to know the truth.
Edit to add: It is a computer telling them how fast to go, usually something similar to http://www.scangauge.com/
That doesn't seem to be the majority here.
Tailgating is often the _cause_ of the jam.
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.
I'd never have thought of it this way, but it's so simple. Thanks.
That's how the traffic jam happens in the first place. An accident happens, closing a lane, but the impatient people in that lane don't merge until the last second, forcing the people in the next lane to slow down quickly. Some people in the next lane don't leave room for cars to merge, forcing them to merge later, forcing them to do so at a slower speed, slowing down all the cars behind them in a cascading wave of brake lights.
What you're imagining might be possible with cooperative, AI-driven convoys of cars...until a black hat breaks in to their software over the Internet and makes them crash.[1]
What helps is to provide a buffer in your lane by moving at a consistent speed, avoiding braking altogether. Of course idiots are going to get mad and zoom around you once in a while, and that's fine, because they will clear space behind the wave, allowing traffic behind to move more smoothly.
The bottom line is that you can't control what other drivers do, and many drivers are stupid. You can control what you do, leaving more space, maintaining safe following distance, leaving room for cars to merge easily ahead of you, increasing your gas mileage by not braking, etc.
1: http://www.wired.com/2015/07/hackers-remotely-kill-jeep-high...
Either way, this makes me think that a model where cars that are okay with driving slowly spreading around but leaving plenty of space in front of them. Similar to how (in California at least) motorcycles can filter filter though the traffic, cars that are impatient can use the large spacing between the slow moving cars to move forward.
Probably a good indicator you are going too slow.
Which is okay, just please, please, PLEASE stay in the right lane.
Not necessarily. It dense, slow traffic, short-sighted drivers see open spaces; they rush for it, then slam on their brakes. It's amusing the frustration that this generates--for no real reason other than "I'm mad and going to tailgate you because you aren't tailgating the person in front of you".
If people swoop in front of me, Oh well. It's a pittance on my overall commute time, if effecting it at all. Generally it's just limited two a few very aggressive drivers, and I'd rather they tailgate the person in front of me rather than me.
Brake lights being a binary representation of an analogue pedal is another problem, although iirc on some newer cars the lights are brighter/more lights go on the harder you brake
Cool about brake lights; I've wondered for years why they don't do this. I knew about some newer cars flashing the hazard lights in a very hard stop, but didn't know any were doing brake light meters. Any idea which specific models? I'd love if they standardized the messaging across brands and countries; imagine a new mustang where 1 vertical bar on each side means light braking, 2 means moderate, and 3 + rapid flashing means very hard braking. Not sure what standard would make the most sense for this, but the sooner, the better, so new cars can adopt it. It's way less useful / less clear when each car does it differently.
I think that if something like this was implemented, then a lot of people would use it as a crutch and make poor decisions based on implied safety eg, "His light didn't blink three times, so I didn't think to stop." That, and a lot of new cars, for some stupid reason, seem to want to obfuscate the significance of brake lights by just having them be brighter versions of on-by-default lights anyway or similar.
There definitely is something along those lines that'd be helpful, but I think it might have to be all or nothing there. Flooding phone frequencies with white noise might work, though ;)
I've seen Porsche races on TV where you can see a strobing effect, although LEDs sometimes look strange on video
I play this 'game' all the time, everywhere, and when it's time to slow down more than what simply releasing the pedal does I'll first try to shift down and have the engine brake for me. The latter not only because it lowers fuel usage but also because it makes me keep even more distance, which is the key point for me. It is just so much safer (hitting another car because you cannot brake in time isone of the most common accident types) and leads to much more relaxed driving without fast acceleration/deceleration. Only disadvantage so far: other drivers not understanding it and passing you in anger.
I also like to try and impose a rule of not touching the brakes unless absolutely necessary, and using 20% throttle input at most, that helps with the whole dampening thing.
One last caveat: these techniques only really work for freeways/highways in the developed world. The tragedy of the commons phenomenon is on a whole nother level in places like India or China (se asia in general) or a lot of Latin America or even sixth avenue.
I do the same. It's funny the frustration this seems to cause other people. Frustration from nothing, if they'd think about it.
The other time was after cruising during a lot of short stop and go intervals (so it was easy to judge crawling speed, that is to say). I eventually switched to the lane I needed and the guy who was rubberbanding behind me the entire way (pretty much going 1-10-1mph constantly instead of just sitting at 3 like me) pulled next to me and shook his head. I had a good feeling why, so I rolled down my window as we came to a stop next to each other at a light and asked if there was a problem. He said, "You drive like a dumb ass". "Oh, I do? Please tell me what I was doing wrong so I can improve". "You just drive like a dumbass". "No really, you seem like you know a lot about driving, please enlighten me". And he rolled up his window, the light turned green but he accelerated before the car in front of him had a chance to go (perhaps to get away from me, I'm 6'2" and 250lbs.), and then slammed on his brakes again...
Dunning-Kruger, if you ask me.
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 be reached, easily.
Of course, I expect it to take decades for us to reach that point, which is really unfortunate. That's a lot of senseless auto collision deaths due to human error while we wait for the future to arrive. If governments were capable of looking forward, at all, they would recognize the massive savings an all AI road represents, both monetary and health, and would be pushing hard for it (both enabling private industry to implement it and guiding public funded research).
Still though, even a few vehicles "eating traffic waves" can break up a traffic jam. I've heard the number put at 3-5% of traffic being self-driving would prevent phantom traffic jams.
So overall I would say that self-driving cars could help reduce phantom traffic jams, but they may actually increase real traffic jams caused by overcapacity.
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.
But they would have to be much higher than in most proposals, and they should be much lower or non-existence during hours when they're not choked despite the zero price.
I'm not a big fan of the mentality that the transportation system should suck just so we can avoid the rich have better options than the poor. Taken seriously, that would mean a ban on air travel because the poor can't have as much.
If you meant emergency vehicles, those always have priority :-p
Granted, bad night time traffic is often aided by construction. But, that does not help when your parked on a freeway at 3AM.
The thing to keep in mind is that AI can limit the extra space between the cars as well as increase the speed those cars can safely travel. The cars will spend substantially less time on the road because they'll be going faster. Double the speed and you've converted a 60 minute commute into a 30 minute commute, doubling the number of commuters the roadway can support even if you don't adjust inter-car distance art all.
This means that if one car in a densely packed column fails (blowout, engine seizure, ...) then the car immediately behind it is still subject to its mechanical ability to avoid a collision (swerve into empty space or brake to a hard stop at speed) no matter how fast it reacts.
But as soon as the traffic lightens a bit, idiots just come back to break the peace. I include myself in those.
Annoying and led to no end of arguments "Why are you always criticizing my driving!?".
I also try to jump into the left lane at an intersection stop, if there's no left turner, to let people turn right
why does it matter, most of the time?
And then once you do some other genius pulls into the space.
Repeat for entirety of journey.
EDIT: Found in the comments, this may have been it. Honestly don't remember: http://trafficwaves.org/
Edit: I just noticed it still is hosted by eskimo.com, it just has its own domain now.
TL;DR there is an effective maximum number of cars that can pass through a given point of roadway (about 1 car per 2 seconds per lane). No amount of space-leaving is going to chance that.
You also have to take into account cars merging onto the road you are on. Imagine a road acting at peak efficiency, with a car passing every 2 seconds. Now merge in more cars. They are going to push back every car behind by that same 2 seconds.
You can read the section on 'merging' in the link above to read more details.
I think pacer cars might work very well for phantom traffic jams, but I very much disagree about /how/ they should be used. Instead of encouraging an over-capacity jam, I believe that the pacer cars should expressly communicate to other traffic something along the lines of.
"Temporary" / "Speed Limit" / "Follow at XX"
On a rear message board.
The pacer car would then draw out the stuck traffic in to the space /ahead/ of the jam and encourage the compression wave to expand to the front instead.
To minimize fuel consumption, it's best to drive in the highest gear, at the lowest speed for that gear. Failing that, to drive at a constant speed in the highest gear for that speed. If you do have to slow down, ease off the accelerator and change down gears, rather than use the brake. This means thinking ahead. You can do this when approaching a red traffic light, so that it will be green by the time you reach it.
There are a few other tricks to save fuel, such as driving at the minimum safe distance behind a big rig, and using gravity on hills to slow down or speed up.
This is sometimes called hypermiling: https://en.wikipedia.org/wiki/Energy-efficient_driving
62.8 kilometers covered.
I wonder how much more throughput and time saved we could get just by having lines of breakers every 50km or so on a highway during peak times.
I thought 'what happens if the ad is so successful everyone buys that Acura?'
These roads, due to a complete lack of effective urban planning and development, are several times over capacity.
I like to think that this heuristic would be effective for such cases.
* Aim for a hard speed limit (maybe the actual speed limit).
* Actually obey the law of this state: Keep Right Except to Pass.
* ALWAYS allow merges (from either side) with higher priority.
Edit:
After reading the github link from one of the other posts I want to expand why I disagree and suggest always allowing merges.
It is to allow traffic to leave the freeway (merge right to exit) as well as to enter the freeway (merge left, mostly to enter at all, but also in case they're going a long distance or need to get to special use lanes on the left).
That's not gonna work. Depends on the day, the time, the weather, rain, fog etc. Some days, traffic flows at 70 on 405 during rush hour. If you go the legal speed limit you will be the dangerous blockage that makes everyone else down, and makes a few people unnecessarily grumpy. Other days it's misty because the water on the road gets stirred up by all the trucks. It's impossible to go the speed limit on these days, the flow is going 45.
There is no hard rule, except: go with the flow. SEE the traffic. BE the traffic. Do not FIGHT the traffic.
People will learn in a hurry that speeding is pretty much pointless and self-harming.
1) a lot of non-artery roads are really shitty in the UK 2) the UK is an island with lots of rivers and lakes so you may not have an option besides that particular road 3) UK average trips are likely much shorter
If they enforced speed limits on roads in the US with that technique, that road would simply stop being used. There are almost always other options, and the further you are traveling, the more options there are.
I drive like this just to avoid using the clutch. I'll basically crawl at the average speed in 2nd gear, until traffic speeds up.
I suspect truckers may be doing it for the same reason, and their gear ratios mean they would have even more gears to cycle through.
Stop and go would be a huge pain for them if they have to come to a full stop.
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
And if two drivers drive abreast, then it's like having two roads going to the same place, where no one can pass anyone.
A lot of traffic congestion happens because we have nothing but (too-infrequently-used) turn signals to indicate our intentions. If all the cars knew where they were going at an interchange, you could at least optimize the flow.
Of course, there is _no_ solution when there are just too many cars trying to fit on a road that can't handle it. And that's probably 80-90% of the problem anyway :(
You have to externalize the cost of bad behavior by making it a proper market.
For example:
* A small per-second fee that is inversely related to the distance between your vehicle and the vehicle in front or behind you, whichever is closer. Maybe the distance scale would be dynamic based on speed, maybe measured in "estimated stopping time", such as (just as one wild example) a certain fee for being at 100% of safe estimated minimum stopping distance, a smaller one for 200%, a higher one for 50%, negligible or no fee for more than 1000%,
* A penalty fee for changing lanes. In dense or stop and go traffic, changing lanes imposes a pretty large cost on nearby traffic, as both lanes are stopped for a bit. Grass-is-greener temptation causes many drivers to change lanes, which quickly eliminates any sought advantage, but makes traffic worse as drivers essentially take up double space.
* etc?
Then dynamically tune the fees to get the desired result. Watch as frugal drivers economize by
* avoiding tailgating and unnecessary lane changing
* (because of the "minimum of distances" rule) learn to, in denser traffic, balance their available space between front and rear neighbors.
* are loathe to go too slow without making it easier for faster traffic to pass (if you want to enforce speed limits, maybe the distance-to-rear-neighbor cost should only be enforced when travelling below the speed limit?)
* Per-second instead of per-mile fees encourage drivers to avoid already jammed areas
As for hardware -- I guess the kind of hardware needed for adaptive cruise control / lane maintenance/merge assist now found on fancier vehicles is sufficient to measure and operate this (as long as few people successfully hack their toll measurement system, which I honestly think is realistic).
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).
Your post, if we're going to trade snarky political barbs, is a great example of how some people think that some magical form of "regulation" can regulate basic control theory right out of existence. Thinking that any form of regulation could somehow fix this is exactly the same as thinking that they could "fix" gravity. The physics is actually pretty simple at the core, even if the details are complicated. Anywhere you get negative feedback of a certain very, very popular and easy-to-hit form, you get waves. Can't be stopped.
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.
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!
This is a major repost but still misses the main problem. When you look at a car in front of you, you perceive it as a stationary wall, not a moving wall. When you slow down, you're trying to avoid hitting where the car in front of you is when you press on the brake pedal. You're not smart enough to realize that you should be slowing down to avoid hitting where the car will be when that car stops.
You do this, and you should not be driving cars. Leaving space in front of you is an inefficient solution to this problem, now you're overcompensating even more for the problem.
You can try watching one car ahead of the one in front of you to predict when the car in front of you will slow down and need to stop. Your passengers will freak out, constantly thinking you're going to hit the car directly in front of you, because they perceive the car in front of you as a stationary wall. In reality, you're driving more efficiently.
The day when us unevolved meat sacks stop controlling two ton metal bullets can't come soon enough.