Formation of a 'phantom traffic jam'

[wbeaty]

In a simulation with identical drivers, which car is the cause? We have to find the perpetrator, since obviously it's someone else and NOT ME. When I brake, it's to avoid hitting the next car ahead, but when you tap the brakes, it's because you're inferior to me and behaving stupidly. Right? Right?

:)

[ManfredvonKarma7]

So many comments about "one asshole" when the problem is that every single driver is an asshole for not providing enough following distance, forcing a drastic reduction in speed to compensate for a brief braking by another driver.

[UnitedCorpOfAmerica]

I recall my physics professor stating, that in a straight line we can maintain velocity. In an arc or circle we are accelerating due to the constant change in vector.

[dirtjumper23]

@UnitedCorpOfAmerica ...right?

[wbeaty]

All the cars are identical. It's a computer simulation. Yet everyone still blames the "one asshole."

Lol.

[doc5000doc]

No, it doesn't take one asshole to needlessly slow down.... it takes one asshole, who believes himself smarter than the rest, to accelerate, try and overtake...... and break.... and then you have a chocoblock.

[acjones810]

NASCAR!

[teevela]

Good thing I don't drive red rectangles.

[utubepredator]

question is, how much longer does it take to make a full circle when there is no jam, and when there is one ? because, once you get out of the jam, you drive much faster.

[wbeaty]

@utubepredator yeah, then you hit the next wave of the jam.

In Treiber's online java simulator, if one huge jam appeared, I found that it lowered the average speed by 30%. But if lots of little jams appeared, the loss wasn't as great. The real lesson here: don't rush through the empty part and then slam into the next wave, that just keeps the waves going. It slows you down even though it feels like "driving faster."

[utubepredator]

@wbeaty maybe in 5 yrs there will be a working automatic cruise speed adjustment system that drivers will learn to trust, once they see it smooths the entire experience. Actually i'm sure this will happen just before man will begin colonizing the moon and Mars, in 6 years from now...

[wbeaty]

@utubepredator already happened, was in the news

goo.gl / D6KpA

But only expensive cars have ACC cruise control. It takes ~20% of the population to have ACC before jams evaporate.

[utubepredator]

@wbeaty so i dont get credit for reinventing the wheel? :D

[TianSan]

Of course the cop parked on the side of the street is missing, which made that one person scared and slow down.

[chriswel]

Good thing is: while the traffic jam is on the one side, the cars can drive faster on the other side of the circle!

[giantlabs]

Paradox!!!!!!!!!

[FastKart27]

stupid slow ass drivers need to grow some balls and not use the brakes...they wear out everyone elses brakes

[wbeaty]

All the simulated drivers are identical.

The jam appears because they are too close together. The row of cars becomes an "amplifier," and slight drifting of car speeds will turn into a huge "wave."  Going too fast will cause this wave. Slightly taking your foot off the gas will cause this wave.

But the real cause is tailgating.

[swivelingchairguy]

so 1 car reduces its speed and then accelerates back to the initial speed. This causes every car behind it to do the exact same thing. That 1 car's behavior caused way more resources to be used than just its own. Wear and tear on brakes, plus gas to accelerate back to initial speed plus each driver must use more cognitive resources to drive. If the drivers were more spaced out, then the driver's same exact behavior would cost fewer resources.

[7Flabbergasted7]

LOL

this made me laugh for some reason

[2346]

traffics are caused by one carslowing down then another then another till it piles up

[mdadnan]

This is not a traffic jam because rate of passing cars at a single point will average the same.

[WiseWeeabo]

Exactly, it's a 'phantom traffic jam', as the title suggests.

[freesk8]

Not true. There is a speed limit, so the faster traffic can not compensate for the time spent going slowly. All would go faster if they could all drive at the speed limit.

[wbeaty]

> This is not a traffic jam

Sure it is. It's a pattern which, when it appears, causes a drop in flow.

If rate of cars has a constant average, that just means the jam has a stable size and is not growing larger.

[mdadnan]

again, if the delay is not "growing" its not a Jam.

[wbeaty]

Lol. Why argue when the definition of "traffic jam" is in dictionaries. It has everything to do with low flow, and nothing to do with whether flow is constantly decreasing. This vid shows the "jammed state." The unjammed state has higher flow.

Or better, read the traffic dynamics literature. Traffic physicists regard stop-and-go traffic as a series of travelling jams. The above simulation can create multiple jams, or a single jam as shown.

[mdadnan]

[Definition: a number of vehicles so obstructed that they can scarcely move.]

There you go scarcely is like Barely, so I was right. In the video the cars can easily move and cannot be termed as a traffic jam. In America they are so bad people are jammmmmmmmmmed for hourrrrrrssssss...!!!!

[IAmThePartyCrasher]

In a perfect world, only men would be able to drive on highways and there would be segregated parking spaces.

Men would get the smaller parking spaces, because we can fit 20 cars in the same proximity that it takes females to fit....2. This is not the cause of segregation however. The cause is to avoid scratches from homosexuals and women who have anxiety attacks if they're not the first to show up to a discount sale.

[USA3333]

this is gay

[liuton2005]

Even with no breaking there will be a traffic jam because cars can't move at the same exact speed.

[MrNeo2001]

Even on a straight road traffic stops for 'seemingly' no reason. I've been dead stopped for a while then, right back upto speed again with nothing stopping anyone?! Hahaha

[conman45011]

how is this so popular?

[7millimauser]

Never underestimate the power of stupid people in large numbers. That rule works with traffic, fashion, politics, and the shows we see on TV

[mbm13213]

We don't have that problem in Texas.

Our highways don't go in circles like the jackasses in California.

[Greenvalds]

LOL you are so dumb :D

[pahojafo]

u must not drive then, LOOP 820

[mbm13213]

You know what, I hate that part of town.

I avoid 820 at all cost.

Fortunately for me I usually only have to deal with I-35.

[BrotherBearAZ]

You see this everyday in L.A. and at the same spot

[clnmyjts]

all it takes is one dummy to hit his brakes..LOL

[camilok7]

wow!!! how does that happen??

[Pers0n495]

one person hits his brakes because of something. then the guy behind him must brake also so he doesnt hit him. causes a chain reaction.

[DoktorSilverman]

This happens on Irish motorways (don't laugh) all the time - you're sitting there thinking there must be a breakdown or a lane closed up ahead and then you go on about 1/2 mile and suddenly the lane opens up and not a problem in sight. And then you think 'jeez, I was right to be mad and should have started jumping lanes and honking the horn and generally drivign like a lunatic to get beyond this crap'

[Javindo]

That's very clever.

[Gipuloe]

It's so funny. It's symbolic of our lives.

[dmix09]

so all it takes is for one asshole to needlessly slow down... terrific.

[TechTalkGuy]

@dmix09

Exactly true.

I experience exactly that, specifically when driving through Jersey into Manhattan.

This mystery typically happens when a slow poke enters the passing lane until eventually enough traffic backs up behind, then the slow poke switches lanes, thus creating the phantom traffic jam.

[xXmilkieXx]

Damn slowpokes.

[Greenvalds]

Not the damn slowpokes, but idiot fast drivers

[manguy01]

@dmix09 Or all it takes is one speedometer that reads faster than the car is going entering the road and even perhaps leaving again shortly after. (or 2, 3, or 4 next to eachother depending on the number of lanes).

[EWillard44]

@dmix09 Or several to speed up only to go to a screeching halt.

[wbeaty]

Usually you have to brake to avoid colliding. But you don't have to stomp on the gas; that's optional.

Therefore the waves are caused by people trying to "rush ahead" and drive faster than the average speed.  That ends up creating stopped regions where braking is unavoidable, and the average speed is reduced. Fast driving ...is slow.

[MPControl]

good job...

In practical life is not the exactly the same, but you did a great job to show 90% of the situation.

[XioNilrem]

It does do a pretty good job of showing a real life circumstance. When I was commuting to my campus via freeway, there is a chain reaction that occurs for those who break when it is not necessary. And through years of driving, the 'slow down since guy in front is breaking' is grind into us to where one car slows, then the car behind, and so forth. It gets really bad when there are cameras and people going THE speed limit tap their breaks. Really stupid :-/

[xkayne]

I get about 100 miles on the freeway a week, and that's plenty of time to ponder how these jams start. My guess is that most of these are created by two types of people. People that like to weave and accelerate, and people that are overly cautious and slow. Fast person crosses lanes in front of cautious person, cautious person breaks unnecessarily and does not speed up quick enough, cars behind them slow down as well.

[thundabolt]

i don't think a main cause is people wanting to slow down and see what happened

[ZeWrAtH]

I blame the red car...

[andreiduffy]

lol

[wioneo]

agreed, that guy needs to elarn how to drive

[Blueisalightbulb]

lol xD

[decraziness]

@ZeWrAtH lol

[Jinglepuke]

This phantom jam is true, in my country, they put up signs to notify you of an accident about 100m away, everyone instinctively slows down. This causes massive jams on the expressways. And even though the accident is over the sign is always still on. very frustrating...and sometimes causes more accidents :P

[frvfilms]

solution, - take out one or two that started it , and the third will have space to acelerate,

[frvfilms]

1k on # 8 black--jk

[kelfire23]

here is basic evidence that if people would all drive the same speed traffic jams would not happen.

[MidnightRayn]

this was on newscientist last year losers.

and even then it wasn't something I didn't know.

[Merdam9]

imagine if one car was darker.

Would it affect traffic jam??

[atakkuuuuu]

it's cause we don't drive at a consistent speed.

[Merdam9]

can you find the car which first slows down?

[jasonbsa]

yea lol of course

[apo0286]

it's the red one

[thebloads]

but overall arent all the drivers completing one round in the same amount of time?

[TheMixedKid25]

having to slow down to avoid hitting the car in front of you shaves time off how fast you complete a revolutiont. Then add on more time for each car that is in it and this delay is compounded as the front car that is holding up everyone else has to speed up then the guy behind him has to speed up...so on so forth.

[MidnightRayn]

it's a traffic jam genius, wtf do you think?

[thebloads]

the cars speed up after the jam, and slow down at the jam. so shouldnt their av speed be the same?

[MidnightRayn]

within the confines of a jam sure why not. including before the jam occurred? most certainly not.

[thebloads]

i also feel you are being unnecessarily abrasive.

[xxhairstylistx]

uhg phantom traffic jams are horrible they make me so mad

[emilboy8]

What is a "phantom traffic jam"?

I 'm sorry if this seemed a dumb question to you.

[Shawn4168]

It's basically a traffic jam that has no visible cause. No accident blocking the road, no construction zone, or anything like that.

[emilboy8]

Thank you very much! :)

[fuunguus]

Humans shouldn't be allowed to drive. When are these computer controlled cars coming out? I've seen enough tests and showoffs, they drive better than any human being when it comes to highways, motor roads, etc. I think they should push the technology through asap!

[killmeholly]

lol watch the red car at 0:19

[Afromole]

haha, clever

[larry1961]

LOL!!

[Coribec]

I hate slow people in the left lane so much. I don't care if it's a suburban street let me pass goddamnit. I also hate people who merge like snails and slow down to 5mph/8kph before they turn.

[ignuz]

Nothing wrong with traffic jams.. Gives me more time to perve at chicks nearby =)

[GalryZ]

Said like a true nerd.

[BaneOfFreeSpeech]

as long as there is a human element there will be stupid occurrences. if this simulation said all cars go same speed and never stop it would continue forever with not jam.

[EscuchelaLaCiudad]

yes it would!

[BaneOfFreeSpeech]

no they arnt. there is NO way if these cars were programmed to NEVER brake. go a constant speed they would EVER jam up. this little animation isnt a simulation. its based off a test they did in japan look for the video. the human element is what is making someone brake becuase they think their getting to close because they cant control the gas pedal at exactly the same time everyone else is. i repeat this is NOT a simulation but an animation. so you can cram your 9th grade math up yer arse

[weylin6]

It would be even better if they have automated cars that sync together and wont jam up.

[EscuchelaLaCiudad]

well your an idiot because they are..

[weylin6]

Are what?

[schl0tte]

just another moron who likes to insult others over the internet ;)

[weylin6]

he should try harder

[jrubin22]

the left lane is the passing lane. if you aren't passing someone, get out of that lane.

If you don't signal b4 your hit your brakes, you hate America.

[alfrediscool]

not just breaking can be the reason for a traffic jam it can also be the tire size i think

[TheAtheistHero]

This is a great example of why traffic jams will always exist. That is of course until you take humans out of the equation and have cars drive themselves.

[cheeseboat15]

Interesting. Kudos on the animation. It is simple, yet proves it's point easily

[harvey101107]

i hate slow drivers.

[neotype2001]

This is showing you that it's not that more roads are needed, but we need to better educate drivers in how to actually drive. How many of you see at least one incident a day where someone breaks for no reason at all? If we spent only a tenth of what we do on expanding roads and put it into proper driving education, I don't think traffic would be so bad. This won't solve all traffic, but would help alleviate a lot of it.

[DreadHeadJoe]

your so dumb, were the hell did u get that bullshit

[MiniverJD]

Cool spelling, bro.

[Funiecrud]

Why the hell are people arguing over this??!?!?!

[TinhTran]

lol

[intemister]

once a car brakes, then that compression stays in the circuit forever

[CronicNinja]

until there's less cars on the road. usually at night when people go to bed =)

[mollyfucface]

Culwin..LOL!

[goldliquid]

and this is getting so many views because....?

[GaySingleMulatto]

Jam would indicate slow or lack of movement.

[culwin]

FOX has turned this video into a new 3 hours show called 'NASCAR'!

[judokid15]

super lol

[cacadodoheadrs]

LoL FuNnY

[Timerider]

Nope it is caused by not knowing your route, and then stopping or slowing to catch an exit you did not know was there because instead of passing the exit they have missed folks will actually back up on a freeway rather then drive 5 extra blocks.

So like every other problem on the planet Traffic Jams are created by the Arrogance, Hypocrisy, and immaturity of so called adults.. Now you know.

[wresing]

Nice demonstration of the group velocity of a wave running in the opposite direction of the phase velocity. Imagine beams of these cars intersecting and forming self propagating interference patterns. It seems traffic networks may be meta materials with a negative index of refraction.

[ArisoftGats]

wutwutwut

[coocookiersten]

For the trouble of modeling on modern computers, they could (if they haven't yet) show singlet/doublet...etc. jamitons in manhattan lattices and show it as clearly with or without HD.

For cultured situations (where drivers cannot divert through a slum hut) a comparison of phi/4 signage (e.g. Hey, Move It) in experimental and model situations would make a nice civic installation and attraction for public transport.

[ericsatidiitedu]

I find this video terribly sad

[attobuoy]

Dude, nobody messes up. That's kind of the point here.

[SakuraChama]

Well, one person goes a little slower

and it goes from there.

[Wipnum]

Nice illustration of that ripple effect that happens whenever *somebody* messes up.  It'll probably have an impact even an hour later.

[EDesignman]

We like to call this "The NASCAR Dilemma"

[larry1961]

If it is NASCAR then the delimma is that they are going in the wrong direction and there is no pit crew :)

[michaelkipper]

I'd like to know the assumptions made here. Are drivers likely to vigorously accelerate following the blockage and exceed the speed limit to catch up to the car ahead? Do drivers change their behaviour based on the brake lights of the car in front of them? All these variables affect the result.

[openmikescene]

It is certainly wasteful for any of these people to be driving. They probably should not even own cars, as they have nowhere to go, nowhere to park, and nothing to see. Is this in the Midwest, by chance?

[EDesignman]

Well here's your problem... your road is, as we say in the business, an unending existential loop. It's a common mistake. However, this kind of design will do a number on the drivers. They start asking all kinds of questions like 'why am I here' or 'what is the point?' It can be quite a crisis.

[coocookiersten]

There's another kind of design? City people aren't -defined- by knowing they have to work around those things (incl. existential crises/the few unnerving cases where your workaround took you 13 meters off the entrance of your building you used to get to the parking.)