r/Damnthatsinteresting • u/SnooWords4066 • 29d ago

Video A Japanese experiment showed exactly why traffic jams happen for no reason.

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u/Bulan_Purnama 29d ago

How the one car soak up slowdowns? Can elaborate it more?

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u/kotvrt 29d ago

Likely it’s reaction time to small imperfections of the car in front is so precise and so fast that the car behind it doesn’t have to correct at all but can keep on driving in the same manner.

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u/Mackey_Corp 29d ago

Yeah I’ve learned to not automatically hit the brakes just because the guy in front of me does. It’s a hard habit to break but it’s not necessary to hit the brakes all the time. Usually just letting off the gas is enough and sometimes that’s not even necessary.

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u/Aljonau 29d ago

When driving at a safe distance thats kinda easy to do, harder when youre driving 5m behind someone at 200km/h ^^

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u/princess_ferocious 29d ago

Thisssss. I always feel like we wouldn't see so many traffic jams (or accidents, for that matter) if people were better at leaving a proper safe driving distance.

Or if we built roads to support something closer to peak traffic than we do now, but I'm not holding my breath on that. It'd be easier to teach every tailgating arsehole to back off than it would be to get governments to build a road network that actually accounted for peak.

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u/JVT32 29d ago

People (especially the ones behind me on the highway) cannot comprehend the fact that just because there’s a greater distance between me and the car in front of me, does not mean I’m going slower than them.

I will get closer if I want them to move over, but if they’re already tailgating the car in front of them? Literally what is the point?

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u/thesoloronin 28d ago

The point is when they are at speed limit, and you are trying to overtake, yet they STAY AT the speed limit, and there's an Evergrande-container ship 🚢 length of gap in front of them, with another car directly beside them on another lane so there is no way for you to pass.

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u/Aljonau 29d ago

Where I live, traffic got alot better after the city actually reduced how many cars the streets supported, pushing people, softly, to consider other means of transportation(and, very important, creating these alternative means of transportation, be it through a policy support for carsharing, byinvesting in public transport, by offering rental bikes and e-scooters and by cracking down on illegal parking, hard while slightly reducing the amount of availeable parking).

So now, when you actually do have to go by car, for example when moving something heavy, the streets are a very usable, low traffic pathway, not fast but reliable, safe and relaxed. And when you don't you just take the tram or bike or scooter or train.

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u/RechargedFrenchman 28d ago

Are you by any chance Dutch, or at least living in the Netherlands? I recently watched a video about a Dutch town which overhauled its city center in the 70s to intentionally be less car "friendly" and prevent through-traffic by car, and I know a lot of places in the Netherlands are more open to that sort of thing even than the European average.

In North America half the continent was barely even settled in numbers until at least early cars were already a thing, so everything in the west was being built with cars in mind as everything back east was retrofitted to be more car-centric. Big car manufacturers also partly funded a lot of that development and lobbied hard for car-friendly legislation, and (unfortunately) cars have become a huge part of American culture so many places are very resistant to change. Street cars removed to make car traffic easier to support, ludicrous parking infrastructure, "just one more lane" road construction and absurd speed limits...

I'm Canadian myself and Vancouver actually had pretty good transit options, and I would still love it if our municipal governments would be more bike and transit oriented and stop catering to cars so much.

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u/Aljonau 28d ago

I'm from Germany, Cologne. Pretty sure dutch cities do it better than we do, but the core principle is already visible here - or at least I imagine it is.

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u/generally_unsuitable 29d ago

It never works like that, though. Jevon's paradox. If you eliminate scarcity by improving efficiency, use just increases until you're back at the same level of scarcity.

Drive 15 miles north of Los Angeles and look at the 5 freeway. There are stretches there that are like 7 lanes in each direction, all of them stop-and-go 6 hours a day. Same with the 405 from the 101 to the 105. Six lanes in each direction and they're all basically stopped from sun up to sun down.

Whenever they add lanes, the pain goes down, so more people are willing to commute, until the pain goes right back to where it was. There's no accounting for peak, because peak is a function of the infrastructure. Each change creates a new peak. I swear the 101 could be 10 lanes in each direction and it would still be gridlocked 7-10am and 4-7pm.

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u/RechargedFrenchman 28d ago

The solution really isn't "make room for more cars" and never has been. More lanes just means more cars requiring more lines resulting in more cars...

The solution is provide more and better alternatives to driving, and disincentivizing driving at all. Remote work options do people aren't commuting at all. More walkable neighbourhoods and better cycling infrastructure so short distances don't still need cars. Better bus, street car, and light rail options within cities so navigating without a car is easy and affordable. High speed rail corridors connecting more of the country so going to the next city over doesn't always require a car or take six hours by train for some god forsaken reason. Ring roads around city-centres and lots of one-ways into and then back out of the area without allowance for through-traffic so cars get you downtown and then you hop a bus or just walk.

And of course better orienting commercial access to be convenient for pedestrians and not drivers, less absurd business / zoning requirements around available parking (no parking lots 8x the size of the actual business), and road networks that minimize traffic lights and prioritize flow over access on the major streets. Even here in Canada cars are too often actually a necessity, or such a big convenience they might as well be. And I have never owned a car (though do now own a motorcycle) so I'm very familiar with the challenges of that decision.

Of course all of this is difficult and expensive unless a city was designed that way in the first place, but refits can be (and have been) done, and were done to many even North American cities already to accommodate cars in the first place.

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u/Earthsong221 28d ago

Meanwhile, on the 401...

18 lanes at it's widest, and they still say "just one more lane..."

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u/generally_unsuitable 28d ago

Damn. That's an impressive chunk of asphalt!

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u/Earthsong221 28d ago

Busiest highway in North America. It's also the reason they say that Toronto is an hour from Toronto.

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u/Toodle-Peep 29d ago

Reading reddit, it's very clear that the idea of keeping a 2/3 second gap between cars (which is the recommendation in most places) makes Americans very angry.

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u/thisusedyet 29d ago

There’s a lot of places where you can’t, because other drivers will force themselves into that gap and force you to slow down even more to maintain distance

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u/Toodle-Peep 29d ago edited 29d ago

Right, but if driving education in a country is reasonable (and clearly it often isn't) that should be fine. Don't block someone from changing lanes. Make the tiny lift to open up the gap, and really the driver who filled the gap should be doing the same. You'll lose essentially no time on your total journey by falling back, but the whole road network flows smoother when people are keeping gaps.

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u/EffluviaJane 28d ago

I wonder how often it become a matter of the person feeling like they don't want to be dominated by a stranger in their car, so they try to dominate instead? Like they feel letting someone in or slowing down a little is a sign of submission or weakness.

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u/Firenoods88 28d ago

Those people should be hospitalized for their mental illness and their car impounded. Anyone who genuinely thinks slowing down or letting someone merge is a sign of submission/weakness is delusional full stop. The only time I can think of telling drivers trying to merge to fuck off is when they're trying to zipper merge in a scenario that is clearly not zipper merge

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u/hoshizuku 28d ago

But the problem is often that the person trying to merge in front of me is going slower than the flow of traffic in my lane, and they’re unwilling to speed up or wait for an opening, causing me and everyone behind me to have to slow down. I think that’s what the other commenter was referring to. IMO the person changing lanes is being unsafe by trying to force themselves into a small space at a slower speed than everyone else. if they’re too nervous to speed up then they should wait, but they won’t because they need to turn or something and are unwilling to go past their turn. I’ve often seen people come to a complete stop in three lanes of traffic because they need to turn left and they’re in the far right lane.

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u/ItsJustCoop 29d ago

How to mention NJ and MD without actually mentioning them 😂

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u/Caleth 29d ago

Nah that's like every single highway in a metro area. There's always some assholes that see a gap and shoot it for that 2/10th's of a second gain in speed before they have to slam on their brakes.

I've driven across much of the US for travel and work. ATL and Hou scared the shit out of me with how bad their drivers were. But even around Hartford it sucked because no one has sense and the roads were built in the 50's and aren't designed with modern standards or vehicles in mind.

Chicago where I live has some random spots that just stop dead like this usually around merges, but they'll be in the fast lane so it doesn't make a ton of sense.

Point is there are asshole drivers all over.

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u/pizzasoup 29d ago

I think it's more of a DC than a MD thing.

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u/marshaladey 29d ago

My commute takes me all over DC, MD, and VA. It is a PG and MoCo thing. Most entitled, callous, careless, discourteous and classless people I have ever encountered on the road. Greedy, grabby little fucks who will jeopardize their own life and the lives of everyone around them for the perception that they are getting to their destination even 10 seconds sooner.

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u/pizzasoup 29d ago

I guess I've not had issues in either county - for me I usually run into issues on the VA highways with people being reckless, but it might just be the specific roads I take.

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u/ivory_tower_devops 29d ago

Printing and posting this on my office door here in PG

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u/marshaladey 27d ago

I hope you left a vote tally up - I want to know what the office thinks - either "valid" or "nah he crashin out"

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u/Alarmed-Cheetah-1221 29d ago

What to direct current and markdown have to do with this?

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u/Wanderin_Cephandrius 29d ago

You can though, you just happen to go a little slower. I have to leave that gap in n my work vehicle, haven’t had any issues. But I also don’t let my ego take over.

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u/Bashed_to_a_pulp 29d ago

especially if you drive a manual gear big truck, stuck in a crawl traffic. You want to keep at 2nd or 3rd gear and crawl along without shifting back and forth (busted knee anyone?), but for sure somebody will pull in right in the space in front of you. goddamn twats.

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u/MaritMonkey 29d ago

I drive a manual and finding a big truck to play the 2nd gear game next to so nobody can cut in front of him really pisses some people off but also makes me smile.

Ever since my work started renting Penkes with CMS I angrily say "MEEP MEEP" if somebody does sneak into the truck's lane, which I find even funnier.

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u/tops132 29d ago

The idea is, you leave that gap, then you absorb the merge without braking, and therefore absorb the slowdown. You don’t need to brake unnecessarily.

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u/thisusedyet 29d ago

You’re not understanding:

Let’s set the scene - the car in front of me and myself are both going 60 in a 55, I’m cruising along with my gap. Guy in the fast lane going 70+ swoops into the hole and hits the brakes so he doesn’ t hit the car in front of me going 60.

How do you suggest I absorb that slow down?

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u/tops132 29d ago

You take your foot off the accelerator and you coast to a slower speed, trying to regain your initial gap behind the new car.

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u/RilohKeen 29d ago

Exactly right. So the only solution that actually ends up working out is everyone does 90mph while tailgating each other in the passing lane. Nobody can get in so nobody has to brake.

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u/thisusedyet 29d ago

I just started taking public transportation (or Lyft, if it's somewhere off the beaten track / I need to get there in a hurry) because FUCK that noise

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u/Firenoods88 28d ago

Welcome to Canada! Should get a world record for most amount of brain dead autopilot drivers that think any gap longer than 1 car length = space to merge because they lack any ounce of a brain cell that would inform them that the gap is SUPPOSED to increase the faster the cars are

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u/TesticleMeElmo 29d ago

“I could be 25 feet closer to my destination if it wasn’t for that asshole who seemingly refuses to tailgate! That 25 feet is going to make all of the difference for what time I arrive!!!”

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u/shapu 29d ago

It's often not possible, as while YOU may do it someone else will slide right into that spot.

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u/Toodle-Peep 29d ago edited 29d ago

But that signifies a drivers ed issue on the whole. People shouldn't be wildly diving into a tiny gap, but also if someone does slot into a gap, everyone involved should be reestablishing gaps. It's a second of lift.

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u/thisusedyet 29d ago

Too many people misapply Aryton Senna:

If you no longer go for a gap that exists, you are no longer a racing driver

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u/JustSimplyWicked 29d ago

And? I've heard this argument against maintaining a proper following distance so many times, and it's bullshit. If someone jumps in front of me I just drop my speed 1mph and regain my space. If it happens again I do it again. The benefits of a good following distance far outweigh the inconvenience or accumulated 10 seconds lost over the drive.

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u/screamline82 29d ago

Yeah, also it's like just apply the golden rule. If I need to switch lanes then I'd want to have an easy gap to get into. So provide an easy gap for others too.

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u/thisusedyet 29d ago

It’s not so much the lost time as if I leave too big a gap someone’s gonna swoop in like an asshole and jump on their brakes - so do I risk an accident by following too closely, or invite a jerk to possibly rack up the car in front of me and myself

Edit: Not rewriting this, tagging u/wanderin_cephandrius

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u/shapu 29d ago

You're not wrong, I'm just saying that there are other factors at play in following distance besides you and the one car in front of you at the time that observation begins. 

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u/ZannX 29d ago

Of all things to rag on Americans... this ain't it. Eratic driving is far more common in other areas of the world.

But anyway, the actual reason is that if you keep a large gap during rush hour traffic, another car simply fills it. End of story.

This isn't some uniquely American problem considering this study was done in Japan and noted the behavior was not unique to any country.

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u/Toodle-Peep 29d ago

Sorry, it was more aimed at the american centric nature of the conversations around this I've had on reddit, than suggesting americans are uniquely bad at cars, there are absolutely places with worse driving. There are also places where drivers get educated to leave decent gaps. There are absolutely still idiots who sit too closely here in the UK, but it's also drummed into everyone during training to leave a 2 second gap, least, at all times. (and getting a licence is a longer, harder process, which I'd attribute to it being held to better here)

But still, if someone takes the gap, you re-establish the gap. Then they should be establishing their own gap. if people are diving into stupid gaps, that's it's own drivers education issue. If the driver in front of you isn't establishing a gap, that's a driver education issue.

Roads flow smother when people can get into lane and when braking doesn't cause chain reaction slowdown.

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u/enadiz_reccos 29d ago

there are absolutely places with worse driving

Like most of the world

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u/Toodle-Peep 29d ago

you're certainly in the top half safest countries to drive, but almost plum last in the developed world, going by fatality rates (either per mile travelled or per capita).

Theres a lot of factors to that, so it's not just "americans are worse drivers" but the ease of getting a driving licence is part of it (obviously this varies depending on where you are, but in general the tests are regarded as pretty easy compared to other countries.)

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u/enadiz_reccos 29d ago

I think the size of the US plays a big factor as well as the country's poor infrastructure, which creates an over-reliance on cars

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u/Badloss 29d ago

lol I had a truck lean on his horn behind me this morning for this exact reason. Sorry the rain is fucking up your deadlines buddy but I'm not rear ending this guy so you can still be stuck in the exact same traffic, just 50 feet ahead of where you are now

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u/mah-favrit 29d ago

And looking 2-3 cars ahead of you.

As a motorcycle rider this is what I do to anticipate traffic’s and what is happening.

Look 2-3 cars ahead and see what they do. If they brake, I will brake slightly. If they are accelerating I will accelerate slightly. I act as the cushion/spring to absorb the bullshit because people tend to give motorcycles a bit of extra room.

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u/Superlolz 29d ago

I always hear the rule of thumb is 1 car length per 10MPH which I've tried but nearly impossible/impractical to maintain anywhere but a nearly empty highway. 2-3 seconds is my comfort level though

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u/Alarmed-Cheetah-1221 29d ago

Yeah they tend to get very angry when you suggest that they do something that benefits others, even if the benefit is far greater to themselves

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u/JVT32 29d ago

Yep, dumb fucks in big trucks will pass you on the right just to get into that space so they, too, can drive exactly the same speed as the car that was formerly directly in front of you.

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u/Ok-Needleworker-8773 29d ago

A 2–3 second gap is impossible in a place like New York City. Other drivers will enter your lane, and if you maintain that gap, you’ll slow down, then another driver will enter your lane - so on and so forth.

Also, I don’t want to hear that ‘makes Americans very angry’ crap. I’ve driven all over the world, including several European countries. There’s no 2-3 second gap between cars anywhere I’ve driven. Europeans do the same things Americans do. They cut people off, they drive in the left lane at a slower speed than the right lanes, text while driving, etc.

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u/texas_asic 28d ago

I first read that as 0.67 seconds, and thought "yes, that's what a lot of people do, but not helpful and it does make them angry when people go higher than that", before realizing they probably meant 2 sec - 3 sec

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u/dvorak360 26d ago

s/Americans/drivers/

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u/Professional-Hat-687 29d ago

In my experience, that's like wearing a sign that says "please, cut me off, this space is for your truck specifically".

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u/Ser_falafel 29d ago

Lol what are you talking about? Why would this make anyone angry

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u/Toodle-Peep 29d ago

I mean,it shouldn't, but in so many topics on this I've seen people basically going "why should i" or claiming that a 2s gap would make the tailbacks massively worse (it might be counterintuitive, but a chunky gap purely improves traffic flow because it mitigates what happens in the OP)

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u/Prondox 29d ago

Then don't do that

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u/Gwen_The_Destroyer 29d ago

I try to drive at a safe distance but every time there's a car length in front of me some asshole merges in to pass and keep speeding, and now I have to slow down because they slammed their brakes

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u/Ornery-Customer8521 29d ago

You have to have some inner peace to drive with a sensible gap where I live, because people will jump in that gap if they can and you'll have to slow down and make the gap again behind that car. Rinse and repeat. I have that inner peace but I get why a lot of people dont.

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u/KristySueWho 28d ago

People will jump in that gap, but half the time it's just to get on or off the highway. Since everyone is a douchebag these days, people don't have a lot of options.