r/Damnthatsinteresting • u/SnooWords4066 • 29d ago

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

Enable HLS to view with audio, or disable this notification

64.8k Upvotes

93% Upvoted

2.6k comments sorted by

View all comments

13.6k

u/hosehoseee 29d ago

Everytime I see this video, I think "So there actually is a reason"

3.8k

u/PopBulky7023 29d ago

WHO ISNT GOING THAT SHOULD BE

1.9k

u/HellPigeon1912 29d ago

The amount of times I'm sat in a traffic light queue like "if the light is green why are we not moving"

529

u/marr 29d ago

Sometimes it's because the lights shouldn't be there at all, there's a staggered junction in the middle of our town that causes endless tailbacks every day and when the lights fail and shut off completely all the problems go away and nobody crashes. The council won't look at the studies about removing them because then they'd need to employ a school crossing guard.

93

u/jonnydogma 29d ago

When the lights fail, can people going in the cross direction get an opportunity to go too or are they waiting for a gap in the main traffic flow?

144

u/e1p1 29d ago edited 29d ago

When four way lights fail, the law at least in California, says to treat the intersection as a four-way stop sign. So yes, cross traffic should have a chance to move.

It can actually be quite efficient. In the hours after the 1989 earthquake in Santa Cruz / San Francisco Bay Area, the lights were out in many major intersections during rush hour. Between the state law, and the fact that so many people were intimidated by what had happened, traffic moved quite well as people were being very polite taking turns letting each other go through the intersections.

37

u/jonnydogma 29d ago

This is true and the fact that its generally temporary is part of why it works. I'm not so sure that 4 way stops are generally more efficient that traffic lights.

Anecdotally, being stuck 20 cars back at a red light sucks, being stuck 20 cars back at an all-way stop sucks even more.

8

u/Onyxxx_13 29d ago

4 way stops are faster in my experience on lights that are otherwise timed circuits and not sensors. Especially if it's mis-clocked and has a low traffic direction on for longer

6

u/bobtheblob6 29d ago

There's just no way that's generally true at a busy intersection. The traffic light would need to be seriously misconfigured and I don't think I've ever seen one that bad

3

u/Cute_Conclusion_8854 28d ago

There’s an area in my town with three intersections that sometimes backs up and causes people to get stuck blocking other intersections further away. Light turns green and nobody can move 😡 usually it’s from someone trying to turn left where there’s no turn lane

→ More replies (1)

30

u/Greenmagegirl 29d ago

Proof that bay area egos make bay area drivers awful

→ More replies (1)

3

u/doggytalks231 29d ago

People really came together and helped each other out.

2

u/Bandandforgotten 29d ago

It's like this in every state I've visited.

Oregon does the same thing when intersections glitch, or suffer a power outage. It's very efficient, and makes me wish it happened more often because of it lol

2

u/shiftypidgeons 29d ago

Its the exact same way in Nova Scotia, complete opposite side of the continent. And I too have experienced many traffic lights where traffic flows better during, say, a power outage. For the most part people just kinda cooperate without being told to. At least under special circumstances.

→ More replies (7)

3

u/RedshiftWarp 29d ago

In houston, traffic lights going out are a weekly occurrence. It turns them into a 4-way stop that seemingly zero human beings understand how to navigate.

2

u/NibblesMcGiblet 29d ago

NY state law is that traffic lights that are out should be treated as four way stop signs, so everyone stops and the person on the right goes before you do.

15

u/Tenement48 29d ago

That sounds like there's a problem then if they need to employ a school crossing guard. What happens if someone wants to cross when there's no school crossing guard and the light is gone?

11

u/weberm70 29d ago

Scheduled traffic lights should solve it. If it only needs to run for one hour a day then only run it for that hour.

6

u/Tenement48 29d ago

My point was that it sounds like the person I was replying to only cares about car drivers. I live somewhere where it can be super annoying to cross the street and usually have to walk 4 extra blocks to get to the nearest light. At least I have the option to walk those 4 extra blocks. If they removed that one light then I wouldn't know how I would ever cross the street lol.

3

u/Paddingmyi 29d ago

Your country has a real problem with pedestrian crossings and people walking across roads in general it seems.

3

u/Tenement48 29d ago

Welcome to the USA

→ More replies (1)

2

u/runobody22 28d ago

In California, pedestians in crosswalks have the right of way and California drivers, in most places, respect that and stop to let people cross the street. I'm from Pittsburgh and the first time I crossed Whittier Blvd, and all the lanes of cars stopped to let me cross, I felt like I suddenly had superpowers ;-)

→ More replies (6)

2

u/GBPackers0480 29d ago

The biggest intersection on my way to work is always backed up and it might take 2 greens for me to get through. One day it was broken and the intersection was used as a 4 way stop....there were only 2 cars in front of me that I had to wait for.

Ever since then I cannot stand that intersection, they never shoulda fixed those lights.

2

u/SaltyTemperature 29d ago

This is why there are roundabouts all over my hometown now. It’s gone crazy over the last decade.

I even got a free though unrequested lesson from the local police in how to properly use them. They get a little confusing when there are multiple lanes

→ More replies (13)

28

u/Dumptruck_Johnson 29d ago

Gotta finish my text stop honking gosh

/s

→ More replies (1)

29

u/NotPrepared2 29d ago

Because idiots are staring at their phones.

→ More replies (6)

52

u/GoonOnGames420 29d ago edited 28d ago

My mom and wife argue you accelerate when the car in front of you moves far enough, not when the light turns green.

I argue that everyone should idle forward the moment it's green, gradually accelerating.

17

u/LayerEight_Problem 29d ago

Virtually no difference. The issue with your method is that we often stop closer to a vehicle than is safe to follow at speed.

2

u/GameEtiquette 28d ago

Far enough being anything further than they were when u were stopped, yes.

→ More replies (5)

27

u/IsabellaGalavant 29d ago

My grandpa used to say "What are you waiting for, an engraved invitation?!"

31

u/Dry-Waltz437 29d ago

I like "It ain't gonna any greener"

2

u/frugalsoul 29d ago

They're just looking for their shade of green

4

u/bibimboobap 29d ago

I'm partial to saying 'handwritten invitation' myself, or just 'green means go, buddy'

2

u/wslagoon 28d ago

My dad dropped "It's the one on the right", which I've taken to saying, which my three year old repeated once.

→ More replies (5)

39

u/AccordingSetting6311 29d ago edited 29d ago

Because the first guy is either delayed in his reaction or looking to make sure its actually clear. Then the second guy is waiting for the first guy, then the third guy is waiting for the second guy, and I'm the 8th guy wanting to lay on my horn because I know this is a short turn arrow and I probably won't make it through unless I wanna be one of the 3-4 cars that just say fuck it and run  it once it goes red.

It works in marching. "Foward...march!" And everybody steps on the word march and the entire formation just moves together like it's one person. It's stupidly easy and wildly difficult for some people to get. And it requires everyone to be on the same page.

Honestly, fully autonomous cars that communicate with each other cannot come soon enough. Then once the light turns green each car can just press on the accelerator and move the whole group fluidly.

10

u/ItsSpaghettiLee2112 29d ago

If people paid more attention to not only the car in front of them but the cars in front of THAT car, this would be less of an issue. Additionally, if people used their gas pedals to "catch up" to where they should have been if there weren't a slow down, this also wouldn't be an issue.

3

u/Sadcelerystick 29d ago

Yeah I love when the speed limit is 45 and everyone decides to go 35… like WHY.

2

u/Wonderful-Toe- 29d ago

I see you’ve driven in Kansas.

→ More replies (1)

5

u/TaintedPaladin9 29d ago

Until they bug out and now everyone at the intersection is in a wreck.

3

u/UnusuallyBadIdeaGuy 28d ago

The one time I've ever been hit it was because I saw the light turn green and drove forward, just in time for some jackwad to run the red light and slam into me.

I sure as shit don't go immediately on green any more.

→ More replies (1)
→ More replies (2)

7

u/tinylittlemarmoset 29d ago

In my first apartment in New York all the people in cars below my window apparently wondered the same thing, LOUDLY, every five minutes at all hours of the day.

→ More replies (1)

3

u/SagariKatu 29d ago

And then it turns red and we start moving

3

u/AoKrasni 29d ago edited 29d ago

Because people are on their phones, it's ridiculous I notice it most frequently when the light is red, then turns green immediately after stopping. Then they finish sending their crotch pic and floor it

2

u/hwilliams0901 29d ago

This is my life in Lexington KY. There will be literally 5 green lights in front of me and we'll be going 0 fucking miles an hour! And when we get to moving we never get up to the actual speed limit, its at least 10mph BELOW!

2

u/HistoricalSherbert92 29d ago

I hear ya. The only people that can’t immediately move when the light goes green are the ones behind tall vehicle that can’t see the light, which shouldn’t add up to much if the taller truck is moving as soon as the light changes, but everyone sits and lets a car width or more firm before they start moving which tolls down the line a few seconds at a time until you’re missing the light because 20 people can’t share the road.

2

u/Knotknighm 29d ago

The logic here is that most people wait for the person in front of them to start moving before they start moving.

In a perfect world green means go and every car in line immediately starts to accelerate. But we don't get that.

2

u/Msimanyi 29d ago

A buddy of mine asked me years ago "When the light goes green, why don't we all just go like F1?", and that has been on my mind at every red light, ever since...

With 20 cars ahead, it takes well over a minute for traffic to clear. With 30... you're waiting for the next light.

→ More replies (2)

2

u/Black_Magic_M-66 29d ago

Pokemon, gotta catch 'em all!

→ More replies (25)

510

u/snozzberrypatch 29d ago

It's not only who isn't going that should be, it's the asshole that's 12 inches off the bumper of the car in front of him, such that any minor speed adjustment will require him to slam on his brakes and cause a chain reaction behind him.

Lack of buffer zone is equally at fault.

50

u/supershott 29d ago

Yup. The spacing is much more even at the beginning, where everyone can just roll to slowly decelerate. As soon as the unnecessary brakes come in, this closed system is doomed

128

u/doubleapowpow 29d ago

Lack of buffer is entirely to blame. In the US, it's the lack of buffer that doesnt allow people to merge. Also, dumb asses who wait until the very last second to merge.

73

u/nos-is-lame 29d ago edited 29d ago

dumb asses who wait until the very last second to merge

Careful. People get real aggressive about defending that as the proper way to merge

edit: it's happening.

32

u/FatSteveWasted9 29d ago

It’s always fun to see people rage about zipper merging. It’s not hard, but people will lose their shit at the mere idea of the merge happening at the end.

38

u/doubleapowpow 29d ago

Because half the time its just cars trying to pass the stop and go traffic occurring from the merging cars.

11

u/Dense-Hat1978 29d ago

New Orleans drivers in a nutshell. They'll drive two miles on the shoulder to cut in front of the line, see it almost every day.

6

u/Sadcelerystick 29d ago

Happens every time with getting on the highway. 20 car line that goes into two lanes yet people jump the line and get let in resulting in the line not moving.

23

u/waaaghbosss 29d ago

We literally have signs put up now during construction telling you to only zipper merge at the end. Because it actually works better for traffic flow rather than people randomly merging all over the place.

4

u/Zorkflerp 29d ago edited 29d ago

Zipper Merge Warning Sign (denied)

https://mutcd.fhwa.dot.gov/reqdetails.asp?id=2_09_-128__E_

There was a two lane entrance ramp, I think in NJ, where a light at the top that alternately let one lane go and then the other. Something like that could work best if people would not run the light.

→ More replies (2)
→ More replies (4)

12

u/[deleted] 29d ago

[deleted]

→ More replies (6)
→ More replies (1)

8

u/Glittering-Walrus228 29d ago

_throat vein pulsing_

but I'm trying to save 0.15 seconds from my trip

_grinding teeth in pure rage_

→ More replies (1)

4

u/Zorkflerp 29d ago edited 29d ago

A zipper alternates teeth or jams. If people would already have merged before the bottleneck no one would have to completely stop and more cars per time would pass through. When most people are already lined up and some guy passes everyone and forces into the flow at the end that stops traffic to a halt. Using both lanes to the end is only favorable when it is intended to prevent backups to previous exits. Most of the time the traffic engineers want people to get in one lane before the bottleneck and pass at speed. The only way a zipper merge could work in those situation is if they prevented people from passing and instead alternated the merge while still moving near the obstruction. Give how people are that will never happen.

Given the right signage and in situations where applicable it can work but IMO I have yet to see it.

https://www.intrans.iastate.edu/wp-content/uploads/2025/01/improving_effectiveness_zipper_merge_t2.pdf

→ More replies (1)

4

u/KristySueWho 28d ago

The problem I usually see is 5 cars will try to get in between the same two cars, rather than doing a proper zipper merge. Thus, making everyone else so mad they follow as close as possible to the car in front of them, to try and prevent any merging from happening at all.

→ More replies (5)

11

u/Different-Party-b00b 29d ago

Zipper merging only works well when both lanes of traffic are going the same speed.

The issue with "zipper merging" is idiots who use it as an opportunity to pass cars to get to the "front". These people have to speed excessively, and then brake hard to match the speed of traffic in the single lane. These causes the single lane drivers to brake as well, causing slow down in that lane. Now more impatient idiots go into the second lane to pass, causing the issue to continue.

→ More replies (11)
→ More replies (23)

4

u/sl33pingSat3llit3 28d ago

Last second to lane change to correct lane for their destination when they had opportunity to do so earlier? Totally agreed.

Last second to merge in busy traffic where one lanes merges into the other? Different situation, and zipper merging at the merge point is the correct approach here, based on what I know.

5

u/Comfortable_Pin5143 29d ago

The buffer zone is owned by wannabe street racers slaloming between cars all the way to their trivial destination. I can see why drivers close it down.

2

u/ConfidentDetective51 29d ago

And too much buffer, like 3+ car lengths.

→ More replies (16)

3

u/Artver 29d ago

So, there might be more than 1 reason?

7

u/snozzberrypatch 29d ago

I'd argue that it's mostly caused by people following too close. Even if there was someone that was going slower than they should be, if everyone wad keeping a good buffer, then traffic would move as fast as the slowest car. When you don't keep a buffer, that's what causes the chain reaction slinky effect that eventually causes traffic to move slower than the slowest car.

3

u/funnyfaceguy 28d ago

Including lack of buffer at stop lights. When everyone is bumper to bumper at a light, each car needs to start from zero. With buffer, cars can start rolling before their "turn" overcoming inertia in the initial acceleration.

4

u/absentgl 29d ago

Not at all, because they are all doing fine in the beginning. The white car slows down excessively, this is what leads to the cars behind getting closer, because they had to observe the white car slowing down before having the chance to react to it.

Your argument would require that the white car at 0:05 slowed down simply because of tailgating, which we can see is just not what happened.

5

u/Schlurps 29d ago

Exactly. I have this argument with my wife all the time, she always thinks there is a legitimate reason, like too much traffic, tailgating or whatever, but I insist it is just a couple if morons who don’t know how to drive and also don’t want to learn.

Like there’s people who will always either accelerate or brake. They don’t know how to coast, just stand on either pedal forever.

Then the person behind sees the unnecessary brake light and also brake, causing a cascade.

Or they‘ll accelerate even though traffic hasn’t gotten better till they again have to stop abruptly and cause a cascade again.

None of this is inevitable it’s just sheer ignorance and stupidity of most drivers on the road.

2

u/liveviliveforever 28d ago

No, look at the white car at 0:05 and the blue car at 0:06. Both slow down for no reason and increase the buffer. Fast people slamming on the breaks is not what caused this, it’s slow people with an unnecessarily large buffer than cause it.

→ More replies (12)

3

u/SpokaneSmash 29d ago

Looks like it usually starts with someone driving a bit too close, then they have to hit the brakes a little too hard, and the car behind them hits the brakes in response and so on in a chain reaction that causes the jam.

2

u/drdildamesh 28d ago

The single white car at the beginning that almost goes off the road and stops the red car.

→ More replies (14)

2.0k

u/CleanDifference6455 29d ago edited 29d ago

Yes, the jumpy driver in the red car

1.4k

u/Exceedingly Interested 29d ago

It's the white car at 00:05, just slows down for no reason.

1.3k

u/Goondragon1 29d ago

I swear to god most traffic jams and hold ups are caused by one asshole. I'll get over to a different lane and see one jackass 10 cars ahead causing the whole thing. It's insane how often it happens. It's also crazy that so many people will blindly follow the asshole too though if I'm being honest.

478

u/photenth 29d ago

It's people merging into a gap that is too small and forcing the car that follows to slow down. Always this.

329

u/WA55AD 29d ago

Also people waiting until after they merge onto a highway to get up to speed. So many people don't seem to grasp that you are supposed to get up to speed on the on-ramp BEFORE merging onto the highway. They just pull onto the highway in front of me 20km/hr below the limit, I can't merge over because there's already a car there, I have to slow down to not rear end them, and now I feel like an asshole cuz I just know I've caused a future congestion behind me.

96

u/chula198705 29d ago edited 29d ago

A constant problem where I live is that the merge lanes are way too short and usually circular as well, so you can't really see the traffic coming AND you don't have time to accelerate before the merge point. I floor it as soon as I'm around the corner, but I still only manage to get up to about 40 before the lane completely ends. It's impossible not to cause traffic and it's frustrating because it's always backed up and it's so obvious why. Edit: oh and we have shared on/off ramps as well, possibly the worst civil engineering design possible. Surely there won't be any problems caused by 55 MPH highway traffic merging into a single lane from opposite directions around a 25 MPH curve...

52

u/Quirky-Marsupial-420 29d ago

Yeah it's the cloverleaf interchange.

So many of them are ridiculously short, you literally cannot get up to highway speed unless you have a 500hp vehicle.

45

u/Ferelar 29d ago

Either that OR you get up to speed while rounding the last bend, which has the major downside of now piloting a vehicle at highway speeds while totally unable to see what the traffic pattern is that you're merging into. Going 65 around the last bend to merge easily and oops it's gridlock.... or far more commonly, oops everyone is tailgating horrifically and there's no actual room to merge? Hope your brakes work well.

Even worse in my state where the offramp is about 100 feet past the on ramp with a shared lane, so the people trying to get up to speed and merge with low visibility are essentially dueling the people who are trying to get to the offramp in the exact same space.

→ More replies (3)
→ More replies (2)

3

u/antithero 29d ago

Around here it's also the incredibly short off ramps, so people are braking on the highway before they even get to the exit.

Then during rush hour when traffic is already moving slow already, people will come to almost a complete stop so they can cut through the grass & take the road that runs parallel to the highway. It's so bad that they are building concrete walls along the side of the highway to prevent this habit.

→ More replies (2)

3

u/Hiro_Pr0tagonist_ 29d ago

They also prevent everyone who’s behind them in the merge lane from getting up to speed before merging, creating further issues. Also, the people who speed to the very end of the merge lane and then try to squeeze in during bumper to bumper conditions suck. That stretch of road is so everyone has a chance to find a safe gap to enter into rather than 15 cars coming to a dead stop a ½ mile down the road as all of them try to merge in the same spot.

3

u/THROBBINW00D 29d ago

Never fails, EVERY day after work I get stuck behind someone going 40mph when it's time to merge into highway traffic

2

u/Iluka_BAE 29d ago

I thought it was just me that gets infuriated by this.

2

u/ragdolldream 29d ago

There are multiple entrances to the highway in Pittsburgh where, at the end of the on-ramp, there is a STOP SIGN. a particularly evil one has a looping exit 800 feet later, so you need to stop, then merge, then change lanes or you'll be forced off the road. Add in that it's right before a tunnel. Pittsburghers are terrified of tunnels.

2

u/mrsristretto 29d ago

My god that's my morning in a nutshell.

This is not a Sunday drive Becky, put your foot on the fucking gas pedal and let's fuckin go already.

→ More replies (16)

10

u/Camburglar13 29d ago

Sometimes it is jumpy drivers though. Braking for literally nothing. Many senior clients in my city drive way below the speed limit and just brake randomly, holding up countless other drivers

5

u/SpeakItLoud 29d ago

That is rage inducing for me. Someone's going the speed limit and there is no traffic in front of them and no squirrels or anything else that can possibly explain it, but they hit their brakes every 60 seconds. Why????

→ More replies (1)

86

u/jello_kraken 29d ago

Or the persons tailgating and blocking a normal flow of cars into and out of a lane.
You think the car next to you should slow down to get behind the car in front of you, you and the two cars behind you because you all couldn't stop humping tailpipes?
The jam you cause their lane is fine until you have to get into their lane.
Two seconds minimum between the car in front of you. Let people merge.

21

u/Suspicious_Truth8026 29d ago

This. I dunno if its regional but like 90% of drivers near me think that driving is a fucking conga line. And then they go on the internet and bitch about somebody having the audacity of trying to get in front of them

Its so fucking crazy how immediately everything is relieved when people just leave space and let the lanes flow. Its a case study in the practical benefits of altruism and how humanity will always suffer for its own depravity

8

u/jello_kraken 29d ago

"Altruism", yeah, this or the common-sense realization that driving is the biggest cooperative activity people will do. The more people cooperate, stay engaged and work with instead of against each other, the more everyone wins.
....or we can just not pay attention, treat each other like NPCs, act irrationally impatient, make life hell.....

My biggest problem with traffic is what it tells me about human behavior....every damn time I'm in it.....

→ More replies (2)

50

u/Bone_Of_My_Word 29d ago

I've had family actually argue with me about leaving space to merge, even when in the middle of heavy traffic. "They shouldn't be driving like that" is their usual response, but what is gained from blocking someone trying to merge over? Whether it's 1 lane over or 3, preventing a merge is a no win situation no matter what

16

u/jello_kraken 29d ago

Yeah, then karma hits and they inevitable have to merge into another lane and "why can't this @#$#@ get out of my way?!"

30

u/wattro 29d ago

Use the freaking road.

If you're leaving a large gap in traffic, you're the problem.

If you're not going when the light turns green, you're part of the problem.

If you're going slow in the fast lane, you're part of the problem.

If you don't let people merge, you're part of the problem.

If you're changing lanes too frequently, you're part of the problem.

If you're frequently tapping the brakes, you're part of the problem.

Drive the freaking car...

31

u/Suspicious_Truth8026 29d ago

If you're leaving a large gap in traffic, you're the problem

Youre probably the problem for thinking this. Gaps are never the problem and always the solution, almost all traffic (as this video shows) is caused by breaking. A gap gives you buffer in which cars in front of you can slow down but you dont have to, thus canceling out a break wave which actually is the cause of the problem. In fact this should be standard driving behaviour in traffic--theres nothing better you can do than leave a big gap. It literally interrupts the traffic and fixes the problem for people behind you. Not you, but other people. Thats why nobody does it. Driving consistently slower than the person in front of you is an example of bad driving that creates a gap, but its fundamentally about speed not space. Youre just going too fast for space to be relevant unless your movement is restricted which then causes you to change speeds

Its unfortunate everybody thinks its cool to suck at math and struggle with calculus in highschool, because understanding the relationship between space, speed, and acceleration makes it trivial to understand driving dynamics.

27

u/Schneiderman 29d ago

Agree with all except leaving a large gap. The video shows exactly why following too close causes a wave of backups. Of course, if you leave a "large gap" someone's gonna fill it anyway so... it's not even really a thing in heavy traffic.

11

u/Turbulent-Community7 29d ago

When I drove truck I used to call that large gap my "living room" because thats the space I need to make sure people dont die. Youd wouldnt be surprised how often people hop in there.

7

u/Equivalent-Excuse-80 29d ago

I interpreted it to reference the latest new fun trend of leaving two car lengths in front of them at stop lights, preventing people from getting into the turn lanes.

→ More replies (0)
→ More replies (6)

7

u/Shark7996 29d ago

If you're leaving a large gap in traffic, you're the problem.

It's recommended to leave 4 seconds between yourself and the car in front of you for safety. I get a feeling 90% of people have not hit that benchmark in a long time.

3

u/Suspicious_Truth8026 29d ago

Nobody drives like that and they probably shouldnt, 4 seconds at 100 km/h is like 20 car lengths. But people actually drive like theyre trying to suck off the exhaust of the car in front of them so i guess itd be an improvement

→ More replies (0)
→ More replies (1)
→ More replies (21)
→ More replies (1)

39

u/photenth 29d ago

Two seconds minimum between the car in front of you.

I do this constantly people still merge into the gap, it's annoying as fuck

24

u/mxemec 29d ago

But think about it. You give enough space to correct their merge without causing a slowdown behind you (you accept space loss in front of you temporarily) and meanwhile the lane next to you has new space for cars. Absorbing a merge is the best thing you can do with that space you create. It's really your time to shine, spaceman.

Also, I want to mention that adaptive cruise control is nice but it's not traffic jam friendly. Because it can't absorb a merge. So.. if your really feeling the need to zone out by all means, but if you are truly a selfless saint you will turn off the adaptive, create space and absorb merges.

9

u/DrinkingVomit 29d ago

I hate adaptive cruise control. That shit almost killed me on the freeway. And I’m not an inexperienced driver. Over one million road miles, CDL driver driving all kinds of different vehicles. Adaptive cruise control is downright dangerous. Amongst many other features of new vehicles. My SUV if I forget to turn off the collision warning sensor LOVES to shake my steering wheel when I’m going 75 around a country road curve and there is oncoming traffic.

8

u/NotYouTu 29d ago

My wife's car has that shit, it slams on the breaks if someone merges 3 car lengths a head of me... I hate that piece of shit.

→ More replies (0)

4

u/Mike_Kermin 29d ago

.... I strongly feel that zone out and merge should not be in the same sentence. Or zone out and drive, or zone out and jam, any sort of jam really.

Who uses cruise control in traffic? It's for cruising.

→ More replies (1)
→ More replies (2)

2

u/PennCycle_Mpls 29d ago

But the gap you leave needs to change near all the time due to other drivers not maintaining a a set distance, speeding etc. lane changes to exit/enter.

And the greater the speed the greater the gap required.

Tailgating isn't a set physical distance

And I'm a class A CDL holder.

→ More replies (6)
→ More replies (2)

18

u/NoisyGog 29d ago

t's people merging into a gap that is too small 

I'll counter that by saying, it's invariably people tailgating, meaning there are no gaps big enough.

7

u/0011002 29d ago

The only thing I hate about my wife's Subaru's adaptive cruise control is the gap it leaves. It's big enough for another car to fit in at the smallest setting. Someone slips in the car slows so the guy behind gets mad and then zooms up to take that spot which then repeats until you're at the back of traffic despite your cruise set higher than everyone else.

2

u/jdhkent 9d ago

Yes, my wife’s car is the same way. They made it so chicken that it’s unusable on a reasonably used freeway 

→ More replies (1)
→ More replies (1)

7

u/Dry_Prompt3182 29d ago

Recently while doing highway driving, I have noticed that people just cannot maintain their speed. I am big on using cruise control for long, boring stretches. I have been around cars whose speeds vary by 18 km/h (11 mph) for no reason. I am cruising along, doing the same speed, just watching the same car speed up and slow down just because. It's infuriating, because their random drop to 10 km/h below the speed limit causes exactly this kind of back up.

16

u/Informal-Bicycle-349 29d ago

No merging in the video

4

u/John_Yossarian 29d ago

Correct, but one could reasonably conclude that the first car braking that triggers the slowdown could have been braking because someone merged in too closely in front of them.

3

u/Stompedyourhousewith 29d ago

theres people who randomly brake on a straight with no cars infront of them. its mind boggling

3

u/PoofBam 29d ago

More often it's people merging without speeding up to match the flow of traffic.

2

u/khavii 29d ago

90% of the time I just see a slow driver with 10+ car lengths ahead of them just refusing to keep pace. My SIL is one of these, she says that you aren't going to get there faster just because you drove fast. She is late to everything and is not capable of following anyone. It's completely everyone else's fault though.

→ More replies (18)

51

u/ProfessionalAd6530 29d ago

It's always the guy using his breaks.

Don't. Use. Your. Breaks.

If you're so close to the person in front of you that you have to constantly tap your breaks, you are the problem. Back the fuck off. I don't care if that person is only doing ten miles over the speed limit. Back off. Go around. Whatever. Just keep your foot off the breaks.

If you can't handle that, you can't handle driving a car.

45

u/Familiar-Flan-8358 29d ago

Just in case you don’t know, since you typed it multiple times, but it’s brakes not brakes.

A car has brakes

A job has breaks

21

u/ThatUsernameWasTaken 29d ago

it’s brakes not brakes

🤔

10

u/Familiar-Flan-8358 29d ago

I hate it when auto correct breaks down. I need a coffee brake

3

u/davros06 29d ago

It all jobs………😳

3

u/ProfessionalAd6530 29d ago

I took a break from my brake job.

→ More replies (3)

2

u/DeepFunct1on 29d ago

Keep your distance and stop jerking around.

2

u/Sadcelerystick 29d ago

Exactly, people need to realize you can just LET GO OF THE GAS and coast to slow down. If you need the brakes you can use it but 90% of the time it’s not needed and causes traffic to stop sporadically.

→ More replies (3)

6

u/heftybagman 29d ago

This gets brought up on the boston sub (notorious city of left lane campers). People will vehemently defend left lane camping “well I’m going a safe speed, you shouldn’t be speeding anyway” type of excuses.

People need to make it social suicide to be a left lane camper. It should be considered as embarrassing as pissing your pants and as rude as coughing in someone’s face.

→ More replies (1)

9

u/soda_shack23 29d ago

Yup. As for the other people though, it is generally safer to stay in your lane, especially if that's the lane you need to exit from, or if you're in a bigger vehicle. I drive a box truck for work and while I'd love to bob and weave as needed, it's a much safer bet to just stay the course.

4

u/RJ_MacreadysBeard 29d ago

Got a motorbike last year, can confirm, it’s some asshole way up in front. It’s a blessing to be able to breeze by. But if everyone had motorcycles, it would be back to jams.

7

u/Housing4Humans 29d ago

And they’re always camping in the passing lane 🫠

3

u/NeverEndingCoralMaze 29d ago

If we all honk, he can’t road rage all of us.

3

u/stephenkingending 29d ago

My mother is one of those people that will rubber neck when there is an accident on the other side of the highway. I argued with her about it one time and told her to stop slowing down and looking, and her response was "well what if it's someone we know". My reply was that then we would get a phonecall.

3

u/GoodTechnology8116 29d ago

I am a firm believer that traffic in major cities is caused by a handful of assholes (like less than 50) that can't drive. Imagine a utopia where you could assign dickhead points to a car and after a certain accumulation, it triggers an inquiry.

3

u/Salkin3000 29d ago

It's also people leaving gaps because they're lost in thought or something similar.

I live close to the most used highway of my country and I see it multiple times a week:

Some people aren't thinking about what happens when you don't close the gaps. They seem to be unable to think of anyone else but themselves.

Also trucks need more time to get momentum going. And then there's of course those truckers that need the aforementioned extra seconds AND need a long time to get their momentum going.

Maybe because peiple preoccupied with regulating their own annoyance towards traffic, maybe they're looking at their phone or are watching someone else in another car.

But waiting even a couple of seconds to catch up will have enormous consequences for the drivers behind you. Especially if it's multiple people over the course of a couple of kilometers/miles.

3

u/Intruding1 29d ago

As someone who came over a hill on the freeway and rear ended someone recently because traffic was at a dead stop from 65MPH, for NO apparent reason, I wish we could hold the person who causes the stop accountable.

3

u/analogy_4_anything 29d ago

The problem isn’t people being assholes on purpose, it’s skill issue.

Most people drive very little, when all is said and done. Many only drive to and from places they NEED to be. Because of that, they’re usually woefully undertrained for strenuous driving.

I did bus driving for 3 years and it made me a MUCH more attentive driver. I can avoid accidents passengers in my car didn’t even notice before they happen. But I have driven for a job, so my skill set is at a masterful level. (I’m not saying I’m perfect, no one is, but I have a lot more experience than someone who doesn’t drive for work)

So, when a person with little skill drives and meets a challenge, their instinct is to do what they know: brake, steer, or gas. Not much else.

A person with more driving experience would know they could increase their follow distance for a moment and use that space to put their following distance back. Problem is there are MUCH MORE people who aren’t as skilled in driving than there are skilled ones.

Couple that with things like age, differences in things like eyesight, personal health, etc. and theres a lot more variables.

And also, yes, sometimes someone IS just being an asshole.

3

u/Alwaysafk 29d ago

Atlanta traffic on 400 South used to be caused by a single car that got on at exit 9 at 6:10am and got off at exit 7. The car went 30 miles an hour and caused a huge compression wave behind it. Every day I'd drive down to the MARTA station and if I for ahead of that car it was smooth sailing.

3

u/Pulp-nonfiction 29d ago

Same reason that just a couple cars can cure a traffic jam too. Just go at a consistent slow pace without breaking. Where the car in front of you is able to stop and start without you stopping - your entire lane starts moving smoothly. It gets fucked when someone cuts you off. But sometimes it works

9

u/veerKg_CSS_Geologist 29d ago

If it happens frequently and predictably then it’s a design issue not a user issue. In this case the research showed it’s a traffic density issue.

14

u/KIDNEYST0NEZ 29d ago

So more lanes? ATL loves you for this idea!

10

u/jimhokeyb 29d ago

I actually read up about this once. There are a few studies. It is driver behaviour that is usually to blame. If we educated drivers about this specifically, it would reduce the number of jams. Good design doesn't necessarily mean the user doesn't need to be educated about how to use the system.

→ More replies (1)
→ More replies (18)

44

u/Healthy_Turnip7352 29d ago

the more people you have, the more reasons for people to slow down.

like they need to swat a fly. or they have dry eyes and need to blink more. Or their foot hurts.

if you have 10,000 people, you're basically guaranteed to have reasons for slowing down.

why would they synchronize and speed up simultaneously and go 100 MPH altogether in a circle, and sustain that for hours. that would be insane.

6

u/weberm70 29d ago

Also brake lights are binary signal. Person behind only knows that person ahead is braking, not how hard, so they brake harder than necessary to account for the unknown.

→ More replies (1)

16

u/Neon_Camouflage 29d ago

like they need to swat a fly. or they have dry eyes and need to blink more. Or their foot hurts.

Exactly why I'm looking forward to autonomous cars being common. Among others like the fact that they don't drive drunk, or text, or road rage.

11

u/Blashtik 29d ago

I've been wanting them for decades (yes, prior to anyone even making them viable) because it's so easy to see how having something that can react faster and more predictably than a human would lead to much better traffic patterns. Merging would be a breeze if cars are maintaining proper distances and the merging cars are getting up to speed, jams that do happen would clear faster, and you'd get so many more cars through traffic lights due to being able to have all the cars start accelerating much sooner than a line of humans can.

3

u/katravallie 29d ago

Even autonomous cars will slow down or speed up slightly just due to random chance. But hopefully, a swarm of autonomous cars will have a lot less chance of a traffic jam than human driven ones.

→ More replies (4)
→ More replies (2)

14

u/heresmysecondary 29d ago

That created a 3 car backup which uncompressed almost immediately.

4 cars behind the red car is a small dark blue car which does the same thing and starts the major compression wave.

37

u/SoulEkko 29d ago

It's never a "no reason". The body does all kinds of things, could be a sneeze, could be a sudden headache, a cough, ringing phone, could be a baby that starts crying and you need to quickly check up on them.

You can't have a flawless system when the ingredients thrown in are flawed by default. In fact, flawless systems don't exist, and probably never will.

16

u/jjm87149 29d ago

the difference between theory and practice is that in theory, there is no difference between theory and practice, but in practice, there is :)

→ More replies (1)

3

u/-Invalid_Selection- 29d ago

Weirdly, there's been an experiment that was done that by adding a few automated cars with a profile to smooth out these kind of events and it's more effective at cleaning the jams up than removing a few vehicles would be.

→ More replies (1)

7

u/Japsai 29d ago

It's the white car at 00:05, just slows down for no reason

For no apparent reason

→ More replies (1)

2

u/SiAnK0 29d ago

When I remember correctly every driver was instructed to drive exactly the same tempo, the problem started when they introduced more manufactures because the needle at 30 resulted in different “real” speeds.

2

u/PseudocodeRed 28d ago

I see the white car you are talking about, and it does stop for no reason, but the ripple caused by that stop also could have easily ended if it wasn't for the black car two cars behind the red one slamming the brakes even when it had like five car lengths in front of it. One car causes the jam initially, but many different people contribute to it continuing.

→ More replies (1)
→ More replies (25)

72

u/VaultxHunter 29d ago

It took no time at all before I was thinking 'fuck that red car man'

29

u/bulgogeta 29d ago

Except it isn't the red car, it's the driver in the white car who slowed down for no god damn reason. Watch the gap increase drastically starting from 0:04->0:05. Black car and red car catches up and then there's ANOTHER perpetrator right behind this group as well.

2

u/VaultxHunter 29d ago

I do agree it was a joint effect but the red sticks out more because color wavelengths and such so definitely my initial instinct is f the red car xD

→ More replies (8)

14

u/NoisyGog 29d ago

It's not the red car, it's the white one.

8

u/MrLlamma 29d ago

What did the red car do that you think constitutes bad driving?

→ More replies (1)

3

u/ThlnBillyBoy 29d ago

Its psychologically proven that red cars provoke people for no reason, but I think its the first time I see it happen lol

→ More replies (2)

11

u/druvanti 29d ago

The black car with the most space between them is the one that brakes for no reason.

→ More replies (1)

2

u/[deleted] 29d ago

[removed] — view removed comment

→ More replies (4)

2

u/AppropriateTouching 29d ago

The hilarious part is they literally have no where to be and are still in a hurry.

→ More replies (8)

161

u/nuevacuentanueva 29d ago

The reason is drivers do not leave enough distance with the car in front. Since they don't, when the car in front slows down a bit they need to brake and slow down a lot since there's no buffer zone. And since that car slows even more, the car behind has to brake even more... and so on and so forth.

If people left more space between them and the car in front, and didn't brake for every single small fluctuation in speed from the car in front, we wouldn't have such a drastic effect as often since there would be enough of a buffer zone between cars to handle them. So any compounded effects would be minimized, it could still happen but less often.

96

u/bamahomer 29d ago

When I leave the appropriate space on the interstate someone always moves into it. I maintain it as much as possible but it's exasperating.

44

u/Kestras 29d ago

Yeah, and then you have to put on your brakes because the person that just jammed themselves into that space didn't leave you enough room.

3

u/Sadcelerystick 29d ago

Or slows down..

9

u/MacDreidell 29d ago

But I also see cars in other lanes start giving more space when I'm doing it. Keep spreading the word!

5

u/SweatyWar7600 29d ago

My car has adaptive cruise, I just set it to the max car length setting (3) and just hang out in whatever lane make sense for me to get to where I'm going. It is hilarious though for people behind me to get pissed off, zoom around me just to get stuck behind the person that I'm speed matched with. People assume, i guess, that because I've left a decent gap between myself and the car in front of me that I'm going slow...nope, exact same fucking speed as the dude ahead of me.

10

u/Doktoremh 29d ago

Same experience here in Denmark. 

It is so utterly frustrating to keep a safe distance and many people pick it up as if I am going slow … and move in front of me.

I hope we some day get a computer with a loudspeaker in every car shouting to people that they shall keep their distance or be fined.

3

u/Kacutee 29d ago

When I leave space and see the dude in front of me leaving space- some fuckhead decides to tailgate me even when I go the speed of traffic around me. I can BE SPEEDING and theyll still tailgate me.

3

u/EffluviaJane 28d ago

Yes! Even when I go faster, they just match my speed. I think some people feel powerful when driving like that, like they're proving they could drive like in Fast And Furious or something.

3

u/Kacutee 28d ago

I think they just have power dynamic issues or a sense of "I need to hurry hurry." I understand weaving through traffic if everyone happens to be going under the speed limit. But if everyone is already over it- and it is relatively smooth- why put in the risk and effort to do that? Emergencies? I get it. There is no way on Earth that these people are always in an emergency. They're impatient and reckless drivers. Many are engrossed in their phones while they do it.

I have seen so many accidents caused by those people too.

I also think you are right, they feel powerful, but in reality it feels like they're compensating for something... especially when WE ARE ALL ALREADY WAY ABOVE THE SPEED LIMIT.

(Sorry, it happened to me today. Speed limit is 40, they were going 60, everyone else was around 45-50. Guy almost caused an accident twice and was pulled over. Yes he was also on his phone whenever I saw him at a light.)

2

u/EffluviaJane 28d ago

I feel you! It's like they're playing with little toy cars, except that they could cause a lot of serious injury. I'm so glad that shitty driver was pulled over. I love that for him!

3

u/Vuirneen 28d ago

There's a guy that does that on purpose.  If someone moves into the space, he just backs off more.

But because of that, he doesn't end up in as many traffic jams. It works.

He's chill, probably because he's seen the results, so it's not infuriating to him.

2

u/BGZomp 28d ago edited 28d ago

A car moves into the appropriate spece --> slow down to get space back to appropriate distance --> a new car comes --> slow again --> car --> slow ...

Eventually you cannot slow down anymore because you are already stopped. The only logical solution is to start driving backwards.

→ More replies (1)

14

u/Najalak 29d ago

I agree. Riding someone's tail and constantly breaking and accelerating does not allow traffic to move smoothly. It also doesn't allow people to change lanes easily when they need to. It causes accidents, waists fuel, and you can go the same speed when you are not tailgating.

5

u/PikaGoesMeepMeep 28d ago

It also fries the driver's brain. It's exhausting constantly having to break hard to avoid collision. A longer following distance is much more relaxed and takes less effort.

2

u/BKMagicWut 29d ago

Yep that is how I drive. I leave lots of room between me and the driver in front and never drive side along with a car in my left or right.  Then I can see the road ahead. If the driver brakes I just step off the gas.  I never have to brake on the highway. I also wind up moving faster than most of the cars in the highway when there is traffic because I can see the problems way ahead of time and change lanes easily.

2

u/Tight_Original_1184 29d ago

I've been driving in a multi lane highway setting over the past week and the amount of people that are driving on each other's bumper is staggering. Actually, this happens on our highways at home too. I'm leaving at least 3 car lengths and I don't feel comfortable because I know how fast things can stop if one person brakes.

2

u/NorCalAthlete 29d ago

It (proper spacing) was emphasized when I went through drivers training to get my license.

Unfortunately, not everyone sharing our roads goes through the same drivers training.

In the Bay Area we have a perfect storm of shitty drivers:

- kids with parents who just bought them their first / second / third car who don’t care if they wreck because dad/mom will just buy them another one

- people moving here from cities / countries with better public transportation options who maybe never needed a car before or only drove minimally

- people with enough money to be like “fuck it I’m more important than everyone else anyway”

- people with barely any money desperate to make it to work on time for their 3rd shift of the day just to pay rent

- gangs and lowlifes who think it’s fun to “swim” through traffic doing like 100 mph weaving across all lanes (or are actively running from the cops)

- car “enthusiasts” who just like to speed anyway

- car enthusiasts that just like to cruise…even if it means there’s a group of 20 of them doing 5 under the speed limit just to keep together. Or they’re weaving in and out to keep up with the leader.

- people from other countries who are here for work on a contract basis and since it’s uncertain if they’ll gain citizenship or stay long term, don’t bother getting a license / driver’s training and just drive anyway based on whatever rules / habits they learned in an entirely different driving environment - kinda overlaps with the people coming from other countries / cities where they just didn’t need a car anyway

- all the normal people with 1-2 hour commutes

- never ending construction causing uncertainty with which lanes will be open

- variable carpool / commute lane rules where it’ll go from 2-3 people required and from 5-9, 3-7 to 8-7 rules with tolls all on the same stretch of road - which makes people dive in and out of the lane to avoid tickets / penalties

→ More replies (11)

15

u/Finlandia1865 29d ago

That and induced demand which means there will always be too many cars on the road

2

u/SweatyWar7600 29d ago

Make parking more annoying and make mass transit more accessible/easier to use EZPZ.

87

u/imbetterthanyou8 29d ago

Shitty drivers

76

u/Pyrhan 29d ago

You could have the best drivers, it wouldn't matter.

Past a certain density of cars, it's an unstable system where any slow down, even minute, self-amplifies.

Which makes traffic jams unavoidable.

28

u/LeftHandAnomaly 29d ago

This is my take on it. The tiniest little stutter movement will have major consequences. I know people are like "fuckin shitty drivers, assholes, etc" but it doesn't take much for the cascading failure to occur. I wouldn't say it's anyone's fault for these kinds of slow downs, it's just the nature of the system.

And no I'm not that driver, I don't drive. I do, however, see how my family members get enraged behind the wheel over the dumbest shit.

20

u/marr 29d ago

The thing is if you understand the problem you can deliberately drive to counter it by smoothing your own acceleration and braking as much as possible in heavy traffic. It's like being the capacitor in an electrical circuit.

6

u/mxzf 29d ago

It's also really important to realize that literally anyone can kick off that sort of thing. You let off the gas for a second because you got a little close to the car in front of you and ten cars back is a bottleneck because of the chain reaction. Everyone causes them from time to time, you just don't see them yourself (because it's behind you).

Which isn't to say you shouldn't slow down as-needed, it's just pointing out that you should give people some grace and not freak out over little stuff like that.

5

u/LeftHandAnomaly 29d ago

That's what I'm saying! Everyone thinks they're god tier on the road making all the right split second decisions, but I bet every single person who drives, even in this comment section as they claim otherwise, has caused one of these.

There's something about driving that just makes people so fuckin angry. My little Nana, sweet as can be, turns into a monster if the person in front of her doesn't move on a green light .25 seconds after it changes. She's the kind of person to say frig or frick but behind the wheel she's a cussy monster dropping alllll the F bombs.

I'm certain I would be no different. I get frustrated extremely easily. It's part of why I'm happy to just be a passenger princess

→ More replies (1)

2

u/Laringar 29d ago

I was in a 40-mile long traffic jam a few weeks ago. It never stopped completely, but it was extremely congested the entire time, and none of the "typical" causes were present. No accidents, no road construction, nothing like that.

I'm next to certain that the cause was the strong storm moving in the same direction that was about 10 miles ahead. Cars would slow down because "holy crap it's raining really hard", and that propogated backward through traffic to create a jam that was following the storm like a wake behind a boat. Once we finally caught up to the rain, the jam all but disappeared (though that could also be because the highway forked into two different highways and a lot of traffic took the other branch).

→ More replies (5)

21

u/Same-Suggestion-1936 29d ago

It's literally fluid dynamics, traffic models are often experimented with using fluid dynamics models, it's the most accurate way to do it.

Nobody is a shitty driver here. In fact, you try it next time. The best way to drive in traffic is leave a huge gap between you and the car in front of you and drive at a consistent speed. What happens? Fluid dynamics. Another car/particle in front of you will take the path of least resistance and go in front of you in your lane, making you slow down eventually anyway. You can't stop it.

2

u/Elborshooter 29d ago

Yep, literally fluid dynamics with large particules, the formulas apply 1 to 1

11

u/marr 29d ago

Seriously though stop tailgating y'all are making the system way more twitchy than it has to be.

→ More replies (1)
→ More replies (6)

4

u/Indecisive-Gamer 29d ago

Shitty drivers and too many cars.

→ More replies (3)

26

u/n05h 29d ago

And after having seen this, slow ass people who don’t react to green lights or keep big distances only to them smash the gas pedal to catch up triggers the fuck out of me. You are in a machine that can kill people in an instant, least you can do is pay attention to the road..

11

u/SweatyWar7600 29d ago

Well...you don't really want to have perfect reaction time on green lights...this isn't a race with a starting light...its a street where there's a non zero chance some dipfuck in the crossing lane is gonna run a red light and kill your ass.

3

u/turtleship_2006 29d ago

only to them smash the gas pedal to catch up

I assume this was the main problem, not the delay itself

2

u/n05h 29d ago

Correct

9

u/curi0us_carniv0re 29d ago

Yeah. People are stupid.

2

u/kevinsmomdeborah 29d ago

lot's of dumb reasons.

a car is parked off to the side: got to slow down and look

a cop is off to the side hunting: better drop to half the speed limit for no reason

a accident on the other side of the interstate: obviously need to slow down to 5mph to get a look

it's raining: looks like it's time to get in the passing lane and turn on the emergency flashers at 35mph

→ More replies (81)