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Hey I studied this in grad school for a bit, and it really is just “someone does some dumb shit which leads to a cascading wave of additional people doing dumb shit which propagates backwards for miles.” Basically when the offered load is getting close to the maximum load, all it takes is one person aggressively changing lanes to throw that section of highway into gridlock, and it will remain that way until the total integrated traffic flux across that incident boundary again falls below the critical offered load inflection point.
Basically, pick a lane and just stay in it. Maintain proper following distance. Counterintuitively, the following distance should be for the speed you want to drive, so even in traffic it should be like 5+ car lengths even though you are going slow. This is because it reduces the offered load, and once that number falls below the critical point, speeds will increase again. Bumper to bumper traffic basically prevents that from happening because it dampens the ability for a “speedup” wave to propagate.
Of course this is all impossible for humans. All it takes is a few idiots to throw off the balance.
So basically: 1. Put people in public transport away from the steering wheel, 2) scale back cars use.
Go back to fuckcars with the rhetoric.
so even in traffic it should be like 5+ car lengths even though you are going slow.
Other drivers: “It’s free real estate”
Secret is to play the game next to a semi. Some semis kinda do it too by engine braking as they see the wave approaching instead of waiting until theyre close to even slow
Yep! All it takes is one person braking, and then the person behind braking, then the person behind them, and eith each braking the overall speed slows down more and more. It creates a wave of traffic. The wave passes through. The starting point I think moves back further and further.
I think about it a lot while I sit in traffic.
I think the issue is more or less slow drivers. One asshole is going 60 in a 70 in the left lane which caused people to pass them which in turn cause the cascade from the maneuvering around the slow person.
Slow drivers are far more dangerous than people don’t 10 15 over the speed limit.
You are incorrect. You are the cause of the traffic jam lol, literally.
Why is Driving Slower than Other Vehicles Just as Dangerous as Speeding? https://share.google/U82ugU39Gc0XOa55G
A Few Slow Drivers Increase the Number of Accidents https://share.google/SUYjn8eEkNNLe5xBO
Slow Drivers: Dangers of Driving Slow | Allstate https://share.google/7GP2waFViHMUqEJYj
Some times you people don’t even know what you’re downvoting.
Are you trying to suggest that driving at higher speeds is safer than driving at lower speeds? Because that goes against the laws of physics
That is exactly what I’m suggesting. And so are the sources I provided.
But let me be clear. People who go slow on purpose in high speed areas are a danger for people trying to go faster. I’m not taking about people speeding recklessly. I’m talking people going 60 in a 70 or 20 in a 35. They cause other drivers to maneuver around them which could cause a situation.
If people pass quickly, then get out of the left lane, nobody needs to brake and start a compression wave
So an entire third of the road is basically left empty so people can speed?
Yes? You arrange the fastest cars at the front and the slowest cars at the back, and the whole blob of traffic spreads out.
There was a really interesting MythBusters episode where they essentially replicate what you’re talking about. Albeit with an “n” of 1 or 2 and a very small scale, but still interesting.
Sad thing is its more than just a few idiots.
The idiots are the majority. So stupidly self absorbed they constantly screw themselves over trying to “get theirs”.
“Pick a lane and stay in it” leads to slow drivers blocking the left lane, no?
You have demonstrated why fundamentally humans suck at driving and this problem is unsolvable.
Not because you asked the question but because it’s not intuitive why.
So long as this has to be explained to anyone it can’t be solved.
I’m genuinely curious: are there adverse effects to an arrangement where the right lane is used by large trucks going 90-100 kph, middle lanes used for normal traffic going 120-130 kph and the left lane kept open for faster traffic? As far as I understand, these issues arise when cars go back and forth between lanes all the time, or when cars go slower than the ones behind them without an open lane to overtake them. If you pick a lane and stay in it, you might cause the second issue
From a purely traffic load perspective, the whole “fast lane” thing doesn’t make a huge difference, and the aggressive obsession with it is actually a big part of the psychology which creates traffic in the first place. Traffic capacity is generally optimized when everyone is traveling close to the same speed and has enough following distance to safely maintain that speed, which is why speed limits are set for the slowest road users. Just in general, speed does not increase road capacity beyond a certain fairly low limit because it requires dramatically increased following distance, or in the absence of such responsible behavior, it massively increases the frequency of traffic disruption.
The worst case is a few people traveling much faster than the slowest road users, as these few users both take up more space, and cause more disruption. The “fast lane” concept is rooted firmly in an unfortunate behavioral reality and has basically no real scientific basis beyond that. Even if you had perfect robot drivers with perfect reaction time and the ability to see far ahead of themselves, the critical capacity speed only increases slightly because the maximum stoping distance is still limited by rubber and asphalt.
I’m a little confused about the mechanism of the speeders causing the disruption. Is it because when they cut in front of someone closely, it causes the driver to hit the brakes to make more room, thus triggering the chain reaction?
Thats a big part of it, yeah. Theres lots of really good comments about it in this thread.
Most traffic jams actually act as a kind of compression wave moving backwards through traffic. Something as small as a squirrel running across the road can cascade into an hour-long jam.
One person brakes, then the person behind them, then the person behind them, but each time they are getting closer to each other (nobody stays equidistant from the car in front of them when braking). This causes a greater and greater slowdown as more cars are compacted into a tighter space, which travels backwards in traffic like a wave. Often the person who caused it doesn’t even realize anything happened.
A lot of mapping software actually estimates a given traffic slowdown by treating traffic as a fluid with a wave moving backwards through it.
That’s also why the best way to relieve traffic is to go at a slow even pace without braking. Every time the someone in heavy traffic runs up the ass of another car and brakes hard, or swerves into the “faster” lane and make someone else brake to not hit them, they cause another brake wave. If you have a few cars intentionally just hanging back and cruising with a big enough gap between them and the cars jocking for position in traffic in front of them, then their brake waves do not propogate behind you and eventually traffic just picks up pace again.
Edit: side bonus, you still get there just as fast, but with a lot less stress fighting assholes for position (minus the ones who fly past you thinking you’re the asshole for not riding someone else’s bumper)
Yeah, in theory it’s great but every time I try it people just cut in front of me then slam on brakes causing me to have to brake then adjust then repeat ad nauseam. People suck.
Yeah, maybe I’m fooling myself but it really seems like hanging back more makes me have to do more sudden braking. Traffic seems smoothest when I’m close enough to discourage cut-ins …. Even if that means Im more at the mercy of traffic in front flowing down a bit
But as a corollary, this is one of the reasons fewer lanes are sometimes better. A main road near me proved this out when they cut back from two lanes in each direction to one plus turn lanes. There’s no more jockeying for position, no more cut-in’s and you no longer have to protect your gap. Traffic is smooth and calm, and it improved accident statistics. Most importantly timing to get through that section is consistently better!
This is why I thought that maybe it would be good to have some kind of pacing cars, e.g. operated by traffic police? I.e. when you already know or can anticipate that there is a large jam building up, you bring in one pacing car on every lane at an appropriate low speed and everyone has to adjust, so the thing you mentioned won’t happen.
The problem with that is people would still do the same stupid shit behind the pace cars which would just cause the same issues.
The only way traffic pace cars would work is with better fundamental training (and enforcement of that training [meaning cops would actually have to regularly ticket people for tailgating]).
Especially here in the usa there are hardly any barriers to getting/keeping your license.
There is a massive amount of drivers who either shouldn’t be on the road at all or with heavy restrictions like not allowed to drive at night, not allowed on the highway, not allowed to drive certain classes of cars (kinda like other countries do for motorcycles because there is zero reason for any joe schmoe to just be able to legally get behind the wheel of something like a supercar on public roads)
This is about 2 decades old now but a bunch of people tried something sorta like a pacing car https://www.youtube.com/watch?v=OoETMCosULQ
Or we could just build trains and other alternatives to cars, which would end up cheaper, faster, safer, environmentally friendly, …but we have big oil.
(Sry, I had to)
Nah, cops being on the highway is one of the big causes of traffic. Everyone slows down to the speed limit when they come up on a cop and many are too timid to pass at all. This causes a huge brake wave and fucks everything up. It’s why I don’t think speed limits should even be a thing or should at least be adjusted because most highways are so low that just about everyone ignores them (and is not harmed doing so) until law enforcement appears. If people want to go slower that’s fine but they need to keep right when they aren’t passing and everyone needs to leave plenty of space in front of them so that traffic is permeable enough that people can get to their exit without causing brake waves and absorb the “shock” when it is necessary for someone to hit their brakes.
You need to give even more space then so that them doing that doesnt make you slow down. People cutting in front of you also helps because those are the assholes causing the brake waves.
Edit: down voters, I’m not saying that he “needs” to do anything as in it is his responsibility or he’s to blame. I’m saying that, if he is going to employ this strategy, that making room for pricks swerving in front of you needs to be part of that strategy in order for the desired outcome to happen. If they are making you brake, then your attempts will not work.
I have adaptive cruise with a settable car length and increasing the gap length just makes the cars behind you act more deranged.
I’ve found the only setting that doesn’t make everyone around me fly off the handle is the lowest (one car gap) setting.
I also drive in the diamond lane on long trips and typically have my upper speed limit set well above what the person in front of me is driving.
This is actually an argument for why these features should be mandatory. Traffic is caused by humans and their silly emotions. These types of self driving features with inter-communication would erase traffic jams.
At that point, you’re the guy doing 15 mph under the limit in the left lane.
Please only attempt this in the right lane.
Everyone is doing 15+ under. We’re taking stop and go traffic. What are you talking about?
Edit: Also the least effective place to do this is the right lane. The right lane can have traffic because exits are backup up onto the highway. The left lanes are the ones only getting backed up due to brake waves.
Then leave another gap. There are finite idiots in the world, and you cannot actually go backwards.
Nicely demonstrated here: https://youtu.be/Suugn-p5C1M
I couldn’t even see the traffic start because the fucking “Related Videos!” popups. God I hate what youtube has become.
Californians te the worst drivers in the world because none of them understand this simple concept. Every day I’m driving, I give more than enough space in front of me for someone to cut me off and I don’t have to brake. It’s simple. However, I’m constantly getting people riding my ass. Switching around me. And being over all menaces just because I’m leaving a roper gap between myself and the car in front of me. It’s wild.
You think drivers from your <country/state/city> are bad? That’s because you have never driven in my <country/state/city>
When idiots ride my ass I slow down.
Im driving the speed limit in the right hand lane and you ride my ass - I let off the gas to the minimum speed (here its usually 45mph)
Im actively passing in the left lane and you ride my ass I let off the gas.
When the idots back off I speed back up. If they start riding me again I slow back down. After a few times of this they usually pull their heads out of their asses and back off/ properly change lanes.
huh, they seem to get that concept on the highways i drive on. big state though, we could live ten hours apart from each other.
Haha true! I’m talking about Southern California. Los Angeles and Orange County.
Adaptive cruise control FTW. Matches speed with the person ahead of me (up to the max that I set) and maintains a gap that I can specify. It starts slowing down long before I’d notice the gap closing if I were doing it myself, so the +/- acceleration is a lot smoother as a result.
So, I don’t know exactly how the adaptive cruise control works. But if it is slowing down and speeding up to maintain a specific distance, that does not fix things. The idea is to maintain a specific speed such that, as the people in front of you accelerate and brake, speed up and slow down, you have enough distance to not have to do that. You should essentially match their average speed with enough gap that their braking doesn’t put them close enough to your bumper that you have to slow down yourself. Normal cruise control would be better (except mine won’t set at speeds under, I think, 20mph) because your speed wont change. Adaptive cruise would make your drive safer, maybe, keeping you from being too close or failing to react to the change in traffic speeds, but I dont think it would solve the traffic issue itself.
You aren’t solving traffic as an individual driver anyway. Sorry to burst everyone’s atomized bubble here but that’s complete nonsense.
If you manually maintain a large gap in front of you, everyone behind you becomes complete weirdos.
We could “solve traffic” by not requiring single occupant car drives to accomplish everything in our daily lives.
You’re quite literally incorrect and talking out of your ass
You’re right of course, the reason traffic exists is because you, DancingBear, cannot be on every roadway in America at the same time.
Seriously dude, have you ever been in traffic? I’m not talking about a small slowdown on a one, two lane, or even four lane road. I’m talking about sitting on the 5 or the 101 in any of the multiple times it becomes a parking lot daily.
Manually maintaining a large gap in front of you is not solving that shit, and it’s frankly ridiculous to suggest that it will.
Keep beating your straw man I guess
In one of the Mission Impossible movies Tom Cruise is supposed to have a boring job no one will ask him about and the movie shows this by having the character talk about traffic patterns. I thought it was interesting information then and think it is interesting now.
Lmao I remember seeing this exact scene as a kid, thinking as he was talking “oh that sounds cool as fuck” and then only from how the scene played out realizing it was supposed to be a significantly boring concept
It’s a great cover story until he meets someone at a party who loves that shit.
It’s kind of funny. The writers probably thought traffic pattern analysis is boring because everyone hates traffic. Actually traffic pattern analysis is interesting because everyone hates traffic.
Do you know of a paper that describes this kind of traffic motion?
Here’s the (abstract of the) paper I was thinking of https://pubsonline.informs.org/doi/abs/10.1287/opre.4.1.42
Appalling that I can’t find a free version of a 70 year old paper. You might be able to find the full text somewhere… I would of course never encourage anything that might run afoul of the scientific publishing protection racket.
Not a paper but a great video I watched about it by braintruffle: https://youtu.be/m74zazYPwkY
I couldn’t find the paper I was thinking of that described the phenomenon of traffic propagating as a pressure wave, but I did find this paper (new to me) that describes a model for simulating how congestion spreads in urban environments (as opposed to an isolated highway, which IIRC the paper that most people reference models). It does have the full text available though, and it looks like a good read and has references that should get you going on the history of congestion research.
I am not an expert; I just found this with a few minutes of searching. If there are experts with better papers I’d be happy to hear from ya!
There are phantom traffic jams where someone breaks hard and it ripples on for ages. You can see on YouTube.
Exactly, it’s entirely because the people in front of you are going slow.
I find it’s the speeders, tailgaters, and the infuriating few that can’t seem to manage to go at the prevailing speed that cause the waves in traffic. The rest is structural - merges, construction, lane reductions, etc. The aforementioned all cause the slowdowns because they move quickly, traffic tends to follow, and end up constantly hitting their brakes riding the ass of the slower traffic. That starts a wave that ends up with traffic stopping when density is high enough.
You can’t control others moving slower than you want, bitching about lane campers changes nothing, but managing a speed/spacing that allows little or no braking does wonders to keep things moving. If only people would bother to do so.
I think about this all the time while commuting. I yearn so much to teach the drivers this one simple trick!
I used to say “Speeding gets you nowhere, fast” but the irony is lost on anyone that does it.
Only ever have to ask, my friend
Heres an overview shot of a traffic pulse.
One person brakes for no reason which leads to everyone else braking. The pulse travels despite there being nothing there. The longer it can take for someone to start up again also can delay the whole thing.
It happens when people tailgate. They over react and it causes an accordion effect.
Or when people drive too aggressively and cut someone off, causing the person being cut off to slam on their brake.
Iirc, the answer is to have someone drive slowly and let other cars pass. It creates a buffer zone that regulates the flow back to normal pace. Or at least that’s what I remember from New Scientist’s video from like a decade ago.
I used to just idle when traffic moved. Slowed down way before i was even close to the car ahead. Played a game where i was trying to move at a constant speed or max fuel econ. Much less stressful to always be moving than gas/brake every 10s, even if you’re moving 5mph.
Really helps to look 3-4 cars ahead for brake lights.
This is like saying you don’t know how a bottleneck works.
A few years ago, I was bitching and moaning about a jam, and my pal just said “you’re not in traffic, you are traffic”.
I know it’s nothing more than a cheeky soundbite but just reframing it like that and knowing I’m part of the problem rather than the exception has made me a lot calmer on slow moving roads.
Plus it has encouraged me to either use public transport more, or just drive to a park-and-ride a mile or three out, and run the rest - facilities permitting of course.
“No John, YOU are the traffic!”
And then John was traffic
Traffic John is what they called him.
I still lose it when I finally get to the front of the jam, and the only reason for said jam is because everyone is stopping to look at an accident on the OTHER SIDE OF THE HIGHWAY.
Yeah, it’s frustrating.
I’m not entirely sure what the rubberneckers want to see either. “Oh look, someone critically injured next to someone who is likely deceased”, because that isn’t a day ruiner at the best of times.
Odd.
Switch to a motorbike, then you can experience righteous anger at the handful of drivers slowing down hundreds of bikes and people in buses.
Funnily enough, I’m planning on getting my licence at some point.
I’ve no interest in motorbikes, I would just love to learn how to ride one safely.
I understood them as expensive toys, like an old Italian project car that’s fun to tool around in in nice weather, but when you need to get to work, you drive your car, but experiencing its role in SEA completely change my perspective. They can be cheap, boring, functional machines, with a suprisingly high capacity. that even a dog can perform basic maintenance on and keep running for decades, that work just fine in rain.
The Mythbusters did it! They couldn’t even get up to speed to begin the first experiment because the traffic jam formed naturally.
Hm, this video isn’t available in my country.
It all starts with someone in the passing lane, not passing, and one or more pissed off people behind them :)
The pissed off people trying to get around causes the wave of people behind them to brake and it snowballs from there.
Yeah I drive around 3 hours on the highway every several weeks. Sometimes on my drive, there’s obviously traffic. A lot of times it will be something like rush hour traffic, a crash, construction, etc.
But then like…a good portion of the time when I come to the very front of the “clog”, I find that it is just a blockade of multiple people going incredibly slowly and taking up all lanes of traffic, refusing to move over despite the fact that they are going under the speed limit.
People drive too close to each other, someone has to slow down and then the car behind slows down a bit more. Repeat until you get to the point someone completely stops. Then the next car stops for slightly longer.
If you leave a safe distance then it wouldn’t happen.
3 fucking seconds
The answer is a simple 3 second gap.
That’s it, just 3-mississippi (or 3-onethousand) seconds behind the car in front of you and most of the avoidable jams go away.
If you do that, someone will move into the gap. If someone moves into the gap you can slow down to make another gap to them, but then someone else will drive into that gap. I don’t know of any major city where you can maintain a 3 second gap during rush hour.
Even worse, if you ever brake to try to create a gap, you’re likely to cause a traffic jam behind you.
Sure, if everybody did follow the suggestion and allowed a 3 second gap you wouldn’t have traffic jams, but that’s just not human nature, apparently.
You’re totally right. It’s a social/culture issue. You doing this on your own isn’t going to do shit. Everyone has to miraculously decide to come together to solve the problem with no one taking advantage. It’s the same reason we can’t do anything about climate change.
Edit: I realize this came off as extremely dismissive about climate change. I still think we should do what we can to, at the very least, reduce effects. It was more just a realistic take of why I think we’re all fucked. I still avoid eating meat, single use garbage, and other wasteful shit, don’t get me wrong.
Can anyone tell me why this is being downvoted? I don’t really care about downvotes, Im more just wondering how I’m wrong.
99% of traffic like this is caused by people following too closely.
Yeah ideally you put 3 seconds between you and the car in front of you. Gives a nice, springy cushion to not brake as much. Your mechanic will also be surprised how much longer your brakes last.
If you’re in traffic (i.e. if you are part of the traffic) and you leave a 3 second gap between you and the car in front of you, another car will drive into that gap. If you back off to create another 3 second gap, it will happen again. Even worse, if you hit the brakes to create that three second gap, even if it’s very lightly, you might cause an even worse traffic jam behind you.
I would prefer to leave a big gap to the traffic in front of me, but in many cases 3 seconds simply isn’t practical. A car merging into the lane in front of you is inherently more dangerous than a car already being in that lane. If you keep trying to maintain a 3 second gap in heavy traffic, not only do you put yourself in more danger as you keep having cars merging in front of you, you also cause more danger to the drivers behind you by constantly backing off or braking to try to maintain a gap.
It would be absolutely wonderful if everybody believed in the 3 second rule. Traffic would flow so much more smoothly. But, apparently that isn’t human nature. And, if you keep fighting for that gap when nobody else believes in it, you can actually make things less safe for yourself and for others.
“if you leave a 3 second gap, there will be enough space for others to safely merge into that space as they need to”
And after they do, there will no longer be a 3 second gap, and you’re now driving too close to the person in front of you.
You don’t have to brake and maintain a hard 3 seconds between gap. Just let off the gas a bit let it slowly restore itself. That gap is there so cars can move in and out as freely as they need.
Depends on how aggressively someone merges in front of you, and what they do once they’re in your lane. Some people will merge way too closely. Some people will merge then slow down suddenly. Sometimes you do need to brake.
If they merge in your lane and then brake, then thats on them, not you. Yes, you will have to brake, but its not you that is being the bad driver. Just create more space between you and the car in front of you again.
You could also look into merging into a different lane temporarily until space is restored.
Too many people were taught, and still teach, the “two car’s length” rule. Which is awful. 2 to 3 seconds is much better and intuitive to figure out.
You say 3, which is great, but I’d settle for 2. Most people on the highways around me leave more like 0.5; I sincerely think the vast majority of people greatly overestimate the amount of space in front of them to the next car.
Two car lengths is ridiculously close. The average car is approx. 4.5m in length. Two car lengths is 9m. The average human reaction speed to visual stimuli is approx 250 milliseconds. At 100 km/h (28 m/s) you would travel 7 metres in that time, and that’s just the time for you to notice the stimulus and react, not to choose an appropriate action. If you’re 2 car lengths behind and the car in front of you brakes hard, you’re going to hit it.
2 seconds behind is 56 metres behind, or 12.5 car lengths. 3 seconds is 18.5 car lengths. Even 0.5 seconds is 3 car lengths. Not enough to safely react to the car in front of you doing something unexpected, but not the tailgating that 2 car lengths implies.
You are thr traffic.
People changing lanes
If everyone stuck to the driving lane and only moved over to pass one car in front of them then there’d be less.
Which one of these is the “driving lane”?
The far right.
So, all cars in the far right lane unless they’re passing someone in the far right lane, in which case they should be in the lane that’s second from the right? All other lanes should be empty at all times?
Yes. (If a lane is closed then the furthest open right lane)
So, you think traffic here would flow better if 4 lanes were completely unused, one lane was only used for passing, and everyone else was in the remaining lane? And you could achieve this without replacing the drivers with robots?
Yes, more lanes result in more traffic because there’s more lanes to cut across for each exit.
There are also more lanes for the cars to move forward in.
