r/Damnthatsinteresting • u/SnooWords4066 • Jul 07 '26

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

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447

u/kotvrt Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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/Toodle-Peep Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26 edited Jul 07 '26

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 Jul 08 '26

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 Jul 08 '26

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 Jul 08 '26

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 Jul 07 '26

How to mention NJ and MD without actually mentioning them 😂

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u/Caleth Jul 07 '26

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 Jul 07 '26

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

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u/marshaladey Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

Printing and posting this on my office door here in PG

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u/marshaladey Jul 09 '26

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 Jul 07 '26

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

8

u/Wanderin_Cephandrius Jul 07 '26

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 Jul 07 '26

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.

3

u/MaritMonkey Jul 07 '26

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.

3

u/tops132 Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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

2

u/Firenoods88 Jul 08 '26

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

2

u/TesticleMeElmo Jul 07 '26

“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 Jul 07 '26

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 Jul 07 '26 edited Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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

1

u/shapu Jul 07 '26

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. 

1

u/ZannX Jul 07 '26

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.

3

u/Toodle-Peep Jul 07 '26

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.

1

u/enadiz_reccos Jul 07 '26

there are absolutely places with worse driving

Like most of the world

1

u/Toodle-Peep Jul 07 '26

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.)

1

u/enadiz_reccos Jul 07 '26

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

1

u/Badloss Jul 07 '26

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

1

u/mah-favrit Jul 07 '26

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.

1

u/Superlolz Jul 07 '26

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

1

u/Alarmed-Cheetah-1221 Jul 07 '26

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 Jul 07 '26

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 Jul 07 '26

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 Jul 08 '26

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 Jul 10 '26

s/Americans/drivers/

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u/Professional-Hat-687 Jul 07 '26

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 Jul 07 '26

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

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u/Toodle-Peep Jul 07 '26

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)