- cross-posted to:
- fuckcars@lemmy.world
- cross-posted to:
- fuckcars@lemmy.world
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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.
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 used to say “Speeding gets you nowhere, fast” but the irony is lost on anyone that does it.
I think about this all the time while commuting. I yearn so much to teach the drivers this one simple trick!
This is like saying you don’t know how a bottleneck works.
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.
Nope that’s just a negative picture of a guy
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.
not slowly, just leave room
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.
Johnny Jam to his mates, or J-Traffz to his record label.
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.
Good shout.
I live fairly rurally and the roads/drivers don’t really lend themselves to new riders.
I think if I lived in a big town or city though, I’d absolutely pick up a chicken chaser and rattle about short distances on one, they seem to be perfect for that sort of use case.
Plus, not that I’m a huge fan of tobacco advertising, bikes in the Rothmans livery look absolutely stunning to me.
Yeah that was a through the matrix moment for me too.
It’s the people not zipper merging correctly. You have idiots entering that are not up to speed and you have idiots breaking for the idiots not up to speed.
On ramps should be required to have their lane not end abruptly which causes the panic. The on ram should continue for at least a 1/4 mile.
Cars cause traffic. Cars changing lanes causes traffic. Cars merging causes traffic. Only solution, get rid of the cars and the system built to cater to them.
This is the correct answer. There isn’t a city on earth that has fixed congestion by building for more cars. It’s the places that build for trains and bikes that are best for driving, ironically.
I’ve literally seen a test with 4 cars driving around a circle, and they tell the drivers, “go at a consistent speed and maintain the distance in front of you” and after 5 minutes they’re all bunched up on one side of the circle. No amount of zipper merging and nice ramps will fix this.
people not zipper merging correctly
Zipper merging is more complicated than driving straight forward and requires both lanes to slow down significantly relative to the cars in front and behind them.
The biggest issue with zipper merging is humans need to not be selfish for it to work. Its very efficient when moving well and everyone is in turn, as soon as 1 asshole sneaks in or prevents a merge, it causes the entire flow to stop.
The biggest issue with zipper merging is humans need to not be selfish for it to work.
The biggest issue is that humans need to be aware of all the cars around them. That means using side and rear mirrors, leaving appropriate space for larger vehicles, keeping track of your place in the line, and - also, yes, not being selfish.
Its very efficient when moving well
If you’ve ever been alongside a semi during a zipper merge, you’d know that’s not true. Their visibility is limited and the vehicle is huge, so they have to move at a glacial pace to complete the merge. Then the people in the leading/trailing positions need to open up a much larger gap than with a traditional car, complicated by the fact that they may not know exactly how big the truck they’re letting in is. And heaven help if there’s something hanging off the back of the vehicle. That’s scary, so it causes nervous drivers to try and get away from the rear of the larger vehicle, which further snarls the traffic.
Like, as a procedure executed by a machine with perfect information of all elements involved, its efficient. As a game theory exercise between individual drivers of different skill and temperament, riding in vehicles of varying sizes, on a road with obstructions and other potential hazards, it is decidedly not efficient.
The best flowing highways I’ve ever seen were ones where the on ramp didn’t end, but became the off ramp for the next exit. Obviously you can’t have that everywhere, but it’s basically a free flow lane that gives time for adjustment. I’ve also seen on ramps (older ones) that aren’t much more than a turn lane, and dangerous if you don’t know the area and traffic patterns.
The issue with this style of lane design is it basically doubles the amount of lane changes that lane experiences, which can make it the most dangerous possible space if exits are close together. I’ve lived around Dallas. It’s scary.
My area kinda has this except the on ramp ends quickly merging into the right lane, then the off ramp starts almost immediately after. It makes traffic worse as cars trying to get on cannot merge effectively because cars want to be in that lane to exit. I find the best flow is having the off ramp before the on ramp, which minimizes right lane conflicts.
idiots breaking
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.
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.
I’ve always said that if you’re using your brakes on the highway and it’s not for an emergency stop, you’re too close to the car in front of you. Even if they’re the type that are on and off the brake constantly, if their speed isn’t changing much you shouldn’t need to follow their example. Of course I try to get out from behind them because they are like crying wolf and one of those brakes might be for real.
When caught in a traffic jam I look for a semi to get behind. They won’t accelerate fast like some car drivers do, and they don’t stop as fast either. Plus they can see better if things area really starting to move or not. Keep a few car lengths behind them and while everyone is doing the start and stop motions, I’m keeping a slow but steady speed usually without needing to brake at all. It’s also less stressful.
I don’t always hang out behind a semi when just doing daily driving, but I will 100% camp out behind one when pulling my trailer - massive fuel savings from reduced wind resistance.
It’s a joy to go an hour using a release of the gas pedal as the “brake“
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’re still moving with traffic, why do you care that someone got in front of you? If you’re slowing so much that lots of people are getting in front at one time, then you’re the obstacle. A 3 second gap changes with speed, if it’s slow traffic that’s less than a car length. And if some asshole muscles their way into a gap unsafely, let them. You’ll still get to your destination far faster than if you hit each other or cause some road rage stupidity because of who is in front.
Driving brings out the worst in people for no gain at all.
If you’re still moving with traffic, why do you care that someone got in front of you?
Because you no longer have a 3 second gap so you can no longer safely react to something happening in front of you.
If you’re slowing so much that lots of people are getting in front at one time, then you’re the obstacle.
That’s my point. If you keep trying to make a 3 second gap and it keeps being filled in, you’re going to cause a traffic problem.
A 3 second gap changes with speed, if it’s slow traffic that’s less than a car length
Technically, sure. If you’re driving at less than 5 km/h and people on foot are passing you, then yes, you can have a 3 second gap with less than 1 car length. But, if you’re driving at less than 5 km/h are you really driving, or are you effectively stopped in traffic?
If all these people are merging in front of you, then the adjacent lanes are moving a lot better, which is helpful for traffic. Less braking is the goal, and if 2 or more lanes aren’t braking as much because you left some space in front of you, then traffic should flow much better.
“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.
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 attribute an uneducated, uncivil approach to human nature, but I have been in human queues around the world, and they vary hugely based on cultural and social differences.
What you think is human nature seems to actually be driving culture in your region.
Yesterday I had a swasticar driver actually let me in on a disorderly merge. I was amazed, it was a first. Clue: nothing about Hondas changes people to be better. Tesla and BMW drivers are just shittier at sharing. This is culturally allowed.
Teach people to drive on the right lane unless they want to overtake somebody. Whoever overtakes you on the left won’t drive into the gap because they also want to overtake whoever is driving in front of you.
It’s too late to teach the entire population how to drive differently now.
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.
At least with climate change, your actions can make things slightly better. It’s not enough to be measurable if only one person does it, but if it’s a tiny pressure in the right direction. But, if you drive in a way that’s too different from how other people drive, you can actually make traffic worse or more dangerous.
Except the person next to you or behind you gets frustrated and cuts you off and you have to hit the brakes and create a traffic pulse.
Well yes, society functions only with cooperation. Uncivil behaviour ends with violence and dismay.
However 3s usually allows for slow adjustments which alleviate caterpillaring.
It’s usually a complex crowd effect created by many participants trying to maneuver among each other in slightly disperate ways.
In Portland OR, it really is because some dingbat slowed down to 20 MPH on the interstate for literally no fucking reason at all.
Taking I-5 into Vancouver from Portland is always horrific. Once you get over the bridge it always clears right up! A big part of that is all the on ramps. There’s so many of them! So everybody is having to make way every 10 feet for someone merging in.
It’s horrendous.
Yeah they could probably stand to lose the more southern of the two ramp sets at Delta Park, feels very extra and overall unhelpful (And I say this as someone who uses that ramp when headed north). Of course ODOT’s solution, beyond replacing the bridge, is to widen I-5 south of the bridge - Which anyone with a brain and 50 years of highway traffic studies can tell us would directly contribute to worsening the problem.
Often they do this because their car is barely limping along and they are trying to make it to the next exit.
This driver is distinct from that driver. We definitely have those too, and they have my sympathies. 10 seconds of engine death vs 10 seconds of brain death.
You are thr traffic.
Its because of two things. One is that people hog the passing lane or try to pass slowly so it takes them a few minutes to overtake a few cars, and also because people drive at different speeds. Some people drive at the speed that feels comfortable, others drive the state imposed speed limit. This creates pockets of dense traffic, and then people try to pass, but there is always the person who tries to pass as slow as possible because they are going a few mph over the speed limit.
Its really just a bad combination of laws, and drivers who are terrified of breaking the law, and people who dont know how to drive correctly in a way to reduce traffic. Also many people are just never consider that others also need to use the roads. They don’t care about traffic. Some people also have health issues, like blindness, or mental handicaps, which means driving at interstate speeds is about all they can muster.
Hey, if you have some physical limitation and cannot or are simply not comfortable going faster, that’s 100% fine (assuming you can operate a car safely). Stay the hell in the right lane and never leave it, thanks
Similar to https://en.m.wikipedia.org/wiki/Turbulence The gist of it is that once you reach critical density people can not drive homogenously anymore and (de-) accelerate constantly to not bump into the next car. The problem could be alleviated with self driving cars which negotiate a uniform speed.
The problem could be alleviated with self driving cars which negotiate a uniform speed.
Other than the obvious public transit solution comment, you are aware that ACC exists right?
We literally have the technology on almost all new cars to keep a uniform distance from the car in front of it. Even without that if people realized you can save fuck all time by speeding on your 30 mile commute we could have cars moving at the speed limit and just have smooth traffic flow without any need for self-driving
Geez… I didn’t want to write an entire essay and just mentioned ONE possible example for improvement, to illustrate my explanation. No need to get salty…
Your solution is a dream. Real solutions already exist, it’s called mass transit.
It exists… Only in movies and games though;)
Years ago I was in LA on business and ended up on I-5. All of a sudden traffic stopped dead. Eventually people were getting out of their cars and walking around. About a half-hour later, traffic started up again. We never saw what was responsible for the blockage. No wreckage, no obvious marks or debris on the pavement, nothing. I’m glad I live in a small city nowhere near California.
https://www.mdpi.com/2076-3417/11/9/4278
TLDR: modeling traffic as a gas leads to fairly accurate predictions. If that doesnt mean anything to you, here’s a decent visualization of how gasses move around in a system. In this analogy, each of the gas particles models a car on the road. https://youtu.be/Hr5Baj3lXFA
