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MIT mathematicians model traffic jams like detonation waves

Most drivers have been stuck in a traffic jam at one point or another. Some of the jams are caused by an accident or closed lanes. Other traffic jams crop up with seemingly no reason.

A group of mathematicians at MIT is working on the development of a new model to explain how and why these so-call phantom traffic jams form. According to the researchers, these types of phantom traffic jams form when there are a lot of cars on the road and small disturbances like a driver hitting the brakes too hard or getting too close to another car. These little disturbances can escalate into a self-sustaining traffic jam.

The model developed by the team of researchers may help road designers build roads to minimize the possibility of phantom traffic jams. The key to the study is the discovery that the mathematics of these jams called jamitons are very similar to the equations used to describe the detonation waves produced by explosions.

The discovery of the jamitons allowed the researchers to solve traffic jam equations first theorized in the 1950's. The equations are reportedly similar to those used in fluid mechanics and model traffic jams as self-sustaining waves. The equations allowed the researchers to calculate the conditions that case a jamitons to form and how fast the jamiton will spread.

According to the researchers, once this type of jamiton forms it is nearly impossible to break up and a driver’s only choice is to wait the jamiton out. The researchers say that the new model can help road designers to determine speed limits that are safer and find stretches of road where accidents are more likely.

One of the researchers, Aslan Kasimov, said, "We wanted to describe this using a mathematical model similar to that of fluid flow." Kasimov and his team say that they discovered that jamitons have a sonic point that separates traffic flow into upstream and downstream components. Communication of the cause of the jamiton to drivers it the downstream segment of traffic is impossible say the researchers.

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The source is pretty simple really
By FITCamaro on 6/10/2009 11:25:09 AM , Rating: 5
Large population centers + people going to work + roads not being large enough + stupid drivers who get in accidents or tie up lanes because they try to move from the far left lane to the far right lane for their exit at the last second = traffic jams

RE: The source is pretty simple really
By FITCamaro on 6/10/2009 11:25:47 AM , Rating: 5
Oh I forgot stupid people who feel the need to slow down to 5 mph to gawk at said accidents.

RE: The source is pretty simple really
By mdogs444 on 6/10/09, Rating: -1
RE: The source is pretty simple really
By mmcdonalataocdotgov on 6/10/2009 11:38:32 AM , Rating: 4
How does that help anything? I mean besides your alone-time fantasies?

RE: The source is pretty simple really
By mdogs444 on 6/10/2009 11:41:35 AM , Rating: 1
It may not change what happened, but it sure makes me feel a lot better...

RE: The source is pretty simple really
By Iaiken on 6/10/2009 1:12:18 PM , Rating: 5
mdogs444 said:
quote:
Look at me! I need attention from people on the Internet in order to find validation for my driving and my life!

Maybe not those words exactly, but that's how it read to me...

From what you just said, I can pretty safely state that you're a part of the problem. Safe following distances not only allow you to stop safely in the event that the driver experiences an emergency, but allow room for drivers in other lanes to maneuver in the event of an emergency and allow for merging traffic to zipper correctly.

But since your driving likely stems from a bloated ego and the mistaken notion that you are more important than the other drivers sharing the road with you, no amount of logical discussion or lecturing will cure you of your bad habits. (You certainly sound 'special' btw...) You might want to consult a therapist...

Have a nice day! :D

RE: The source is pretty simple really
By invidious on 6/10/09, Rating: 0
By Danger D on 6/10/2009 2:07:14 PM , Rating: 5
F*** You is hardly a carefree attitude.

RE: The source is pretty simple really
By Chaser on 6/11/2009 8:42:28 AM , Rating: 2
quote:
Safe following distances not only allow you to stop safely in the event that the driver experiences an emergency, but allow room for drivers in other lanes to maneuver in the event of an emergency and allow for merging traffic to zipper correctly.

When "merging traffic" is entering the highway from an entrance ramp you might want to show some basic courtesy and merge over to the next lane. Rather than your "behind the wheel only, childhood bullied revenge, courage rush."

By Spuke on 6/11/2009 11:45:44 AM , Rating: 2
quote:
When "merging traffic" is entering the highway from an entrance ramp you might want to show some basic courtesy and merge over to the next lane.
When you can safely do so without causing unnecessary braking from those behind you, yes we should be courteous to those merging. At the same time, those that are merging with traffic should understand that the drivers on the freeway do have to allow you to merge and YOU should take the necessary steps to merge properly with traffic without causing undue slowdowns of that traffic. In other words, don't be an a\$\$hole whether you're on the freeway or merging onto the freeway.

RE: The source is pretty simple really
By bhieb on 6/10/2009 11:49:31 AM , Rating: 5
Agreed, so mdog you'd rather I stop while entering a 70+ MPH highway via the on ramp, rather than you following the correct distance at that speed, which would have created more than enough room for a safe merge. If every ahole on the road drives that close at those speeds, where is that an oncomer is supposed to merge. Guess just screw him he can park on the on ramp that will not cause a slow down at all.

I'm not talking about the grandma doing 35 and trying to merge, but your example was that no one should merge because your following too close. And if we assume that your way is the right way then the guy behind you is too close and the guy behind him.... and there is no way to merge.

Here is an idea how about you follow at the correct distance let the people merge, and within a half mile or so spacing should be back to normal.

Or just keep honking and flipping people off that won't make them tap the brakes and slow traffic further at all will it /sarcasm.

RE: The source is pretty simple really
By mdogs444 on 6/10/09, Rating: -1
By bhieb on 6/10/2009 12:06:57 PM , Rating: 5
Actually if you paid attention in driving school, yes they have to yield, but as a courtesy driver you also have a responsibility to let them in safely provided they are doing roughly the same speed (again not the grandma here).

What is your grand solution then. Assuming the highway is at max capacity (everyone is bumper to bumper no more room) do they just sit on the on ramp until rush hour is over? Then you'd be the guy 3 cars deep honking and flipping them off because they cannot merge using your standards. The problem is too many cars simple as that. Yes dumb drivers are a problem, but your point here is not an issue. The guy trying to get in at highway speeds is not the BIG problem, the ahole honking and flipping people off is causing far more "ripples" than that guy.

RE: The source is pretty simple really
By Mitch101 on 6/10/2009 12:36:34 PM , Rating: 5
On the flip side there are idiots who have the mentality NOT IN FRONT OF ME YOU DONT! and speed up closing the hole which would have made merging with the flow smooth but now have a do I go for it or apply the brakes situation because I am running out of room. Sadly I want to say there are more people trying to close that gap by speeding up instead of working with the person trying to merge. Im not trying to pass you but there is much more room in front on you because there are 4 cars tailgating each other behind you.

In all cases I try to change lanes if possible to make for the person merging but not everyone is capable of changing lanes for courtesy.

The reality is there are many people who just cant drive and if you listen to Ron White sometimes you will learn that while you can change just about anything on a person but you cant fix stupid.

By OCedHrt on 6/10/2009 8:26:13 PM , Rating: 2
Everyone is a bit over sensitive here. I don't think mdogs intended the "NOT IN FRONT OF ME" mentality. I have frequently encountered drivers who think turning on the turn signal gives them the right to merge. It doesn't. These are the same drivers that cause accidents by merging into the car next to them.

Applying this to the on ramp: Just because you sped up to 65 or 70 doesn't mean you can merge without looking. As the person entering moving traffic, YOU have to find the space to enter. Of course, a courteous driver on the outside lane does help. In the case of bumper to bumper traffic where there is no space to merge, I'm pretty sure the flow up traffic is not 65+ mph and more like 5 mph. If the traffic can flow up 65+ mph, there WILL be more than your share of adequate spaces to merge into.

RE: The source is pretty simple really
By croc on 6/10/09, Rating: -1
RE: The source is pretty simple really
By omnicronx on 6/10/09, Rating: -1
RE: The source is pretty simple really
By bhieb on 6/10/2009 12:16:25 PM , Rating: 2
quote:
Of course traffic jams are another situation, but when speeds are approaching 60+ MPH you have absolutely no excuse.

The whole point here is in jams or heavy traffic. And even at 60+ in heavy traffic the OP was saying it was the mergers fault. Assuming that there is no available "gap" then the bad driver here is not the guy trying to merge at speed, but the guy not following far enough back. A parking space worth of space at 60+ is too close. If a guy is coming on the ramp at speed and you refuse to let give him a 1/2 second release of the gas, then you are the one forcing the cut off. If he slams into you of course legally he was supposed to yield, but every class/book/teacher out there says you should make room if possible.

RE: The source is pretty simple really
By omnicronx on 6/10/09, Rating: 0
By omnicronx on 6/10/2009 12:48:47 PM , Rating: 1
And please do not bring 'How do I merge when there is a traffic Jam then, if nobody will let me in?' as this is beyond the scope of this study. It has nothing to do with traffic jams that have already occurred but the little things that occur before that could create or make traffic worse than it has to be down the line.

RE: The source is pretty simple really
By Xerstead on 6/10/2009 2:16:22 PM , Rating: 3
The right of way is held by those on the main highway. And if they are driving sensibly with at least a 2 second gap between them and the vehicle in front it is easy to merge with the trafic so the 'right of way' isn't really an issue. This also applies to people tailgating from the sliproad 'demanding' space for a group/stream of cars to join all at once. So back off and leave space.
The 3 car lengths mentioned above is nowhere near enough at those speeds.
quote:
I always look far behind me...

So you've built up enough speed on the sliproad to merge with the traffic, getting near enough the main carrageway to see the traffic... Ahhh, no space for 5,6,7+ cars back up the road. You now have 40 meters to hit your brakes AND STOP from over 60Mph. Hope the person behind you isn't doing the same and concentrating of the traffic 1/2 mile back up the main road as he ploughs into your rear. If you do survive that then you'll need to wait for an even biggher gap to get back up to speed.
quote:
it is your responsibility to merge safely not theirs.

But everybody has the responsibility to drive safely with consideration for other road users. Failure to leave enough space for merging traffic forcing them to hit the brakes is more likely to cause an accident.

By omnicronx on 6/10/2009 2:57:31 PM , Rating: 1
quote:
So you've built up enough speed on the sliproad to merge with the traffic, getting near enough the main carrageway to see the traffic... Ahhh, no space for 5,6,7+ cars back up the road. You now have 40 meters to hit your brakes AND STOP from over 60Mph. Hope the person behind you isn't doing the same and concentrating of the traffic 1/2 mile back up the main road as he ploughs into your rear. If you do survive that then you'll need to wait for an even biggher gap to get back up to speed.
I'm not too sure what you are trying to say here, you preach safe driving and you give a situation in which this is not the case. If there is a car in front of you on an on ramp, you are suppose to give space, a good 4-5 car lengths at least probably more so that you can accelerate and have time to compensate in case the flow of traffic changes. At this point what you are saying is a non issue, you can still find a space to merge and the person 4-5 car lengths behind you will also have ample time to merge.
quote:
But everybody has the responsibility to drive safely with consideration for other road users. Failure to leave enough space for merging traffic forcing them to hit the brakes is more likely to cause an accident.
If you read my posts, I agree with this. That being said if I am giving 3+ car lengths in front and behind me (not that I can control the cars behind), I am not going to slow down because someone can't figure out how to fit into the huge space in front and behind me.

The point here is you should not have to adhere to cars merging in the first place. If you leave enough space in front and behind you, and merging cars watch the oncoming traffic to find a spot to merge(following the advice above of course). This is far more ideal than anything you mention. Perhaps slowing down may be safe for you, but 1 mile down the road, cars also slowing down due to a snake effect that you just caused could be far more harmful in the long run. To others of course, and I guess is half the problem, what do you care as long as you are safe..

RE: The source is pretty simple really
By omnicronx on 6/10/2009 12:08:45 PM , Rating: 2
quote:
Here is an idea how about you follow at the correct distance let the people merge, and within a half mile or so spacing should be back to normal.
Forgot to mention, this is exactly what the article is talking about! Unneeded slowing down causes these ripple effects. If you just compensated your speed until their was a space, the car behind you would not have to slow down to let you in and the snake effect would not occur.

RE: The source is pretty simple really
By bhieb on 6/10/2009 12:25:00 PM , Rating: 2
MIT or no MIT there has to be slow downs. If the highway is full there are no safe gaps to get in, thus a slow down MUST occur. It is a simple bandwidth problem, at least where I live. No amount of "good" driving will fix the lack of roads. Bad drivers add to the problem, but ultimately a road will only hold x cars per min. When more are added via merging then a slow down must happen.

Again not talking about the grandma doing 30 or the ahole cutting in just to cut in, but during rush hour in most metros everyone cannot just keep doing 60+ on good driving alone.

By knutjb on 6/10/2009 12:52:54 PM , Rating: 2
One way to do it is the way it's done on the ring road around London. They have cameras on the road any car causing problems to traffic can be identified and services or police sent. That combined with active signs over each lane that can display different speed limits for each lane and can lower the limit as traffic gets heavier, preventing stop and go and can close down lanes and slow traffic down approaching accidents.

Perfect, no, but I never stopped on the highway like I have in LA. If you can eliminate the surging, traffic moves a whole lot faster. In the UK they have way too many cars as the greenies would like to say, or for the rest of us, not enough roadway for the traffic and their system works remarkably well. It's a far more sophisticated system than how Seattle controls lanes in and out of the city at rush hour(s).

By SilentSin on 6/10/2009 1:24:11 PM , Rating: 2
Absolutely. People do not understand how to drive correctly and are usually far past the point of being "bad drivers" and have landed themselves squarely in "seriously dangerous to drive near" territory.

I live in the greater DC area right in the middle of what I would have to consider one of the top 3 worst areas to drive in the US. The two major culprits are I-66 and I-495/I-95 between DC and Richmond. Here's my list of the most aggravating things I witness on a daily basis that not only annoy the absolute crap out of me, but also add greatly to the problem this article is discussing:

1) People using acceleration lanes, exit lanes, and even EMERGENCY pulloffs as shortcuts around traffic/passing lanes. WOW...I just can't even put it into words how angry these people make me. They don't even make up that much time this way, if any.

2) Changing lanes for no reason. I see people do this a lot. There's no one immediately in front of them to pass, no exit to get over to, nobody tailgating them...I guess they just got bored of their lane so they come into mine to find a friend and invariably go 10 mph under the speed limit, forcing me to change lanes around them. Stay put, jackass.

3) Speed mimicking drivers. I'm referring to the driver who will go the exact same speed as you are no matter what you're trying to do. Ex: They are in my lane going a tad slow so I change lanes and try to pass, fair enough. Obviously this sets something off deep in their innermost psyche. None shall pass! They will try to fit in with the group and go your speed, honest, just give them a chance! When you get over to pass, they increase their own speed to match yours and sit there at your side or in your blind spot so that you cannot effectively pass them or let someone who has come up behind you through because they block you from getting back into your original lane. BE CONSISTENT.

4) Truckers trying to pass one another while going up a steep grade. This usually happens near the bottom of a valley where they've picked up speed and are about to go up the other side. This is especially heinous when the road is only two lanes and so *everyone* behind them must now go the speed of a semi going up a hill (I'll give you a hint: not very fast). Read signs. Remember that one that says "No commercial vehicles except buses in the left lane"? Or how about "Vehicles moving slower than 65mph must use right lane"? Yeah THOSE signs. That's you, buddy.

Most of these issues are all about how people change lanes and merge like idiots, which lead to people slamming on their brakes as talked about in the article. I really feel like the states need to up their standards substantially for the driving portion of the driver's license tests. Specifically concentrate on interstate driving and etiquette and I think we'd see a nice reduction in these "phantom" traffic jams. </rant>

RE: The source is pretty simple really
By UNHchabo on 6/10/2009 4:36:50 PM , Rating: 2
quote:
Here is an idea how about you follow at the correct distance let the people merge, and within a half mile or so spacing should be back to normal.

When I lived in New Hampshire, this is what I believed.

In California, if you leave more than 6 feet of following distance, you will be cut off, causing you to slam on your brakes. The only way for traffic to flow at a consistent speed on California highways is for everyone to tailgate everyone else. I don't like it, but that's how it is.

By Spuke on 6/10/2009 6:34:24 PM , Rating: 2
I agree here. In CA traffic, any gaps are just filled in by other cars. I don't tailgate but it seems that any space larger than a car length is filled in. Mind you, this usually occurs at slow speeds but you need to be ready to brake. Because traffic brakes pretty heavy out here.

By Mojo the Monkey on 6/10/2009 6:46:38 PM , Rating: 2
Absolutely true. The rules are different in Southern California, as I am sure is true for various other localities. When I drive in Northern CA, I look around in bewilderment about how calmly everyone is driving.

By PAPutzback on 6/10/2009 4:15:06 PM , Rating: 2
No it is the people riding the left lane not letting people merge. If I am not the fastest on the highway then I am in the middle or right lanes. But I always move left before coming up on a merge lane. Those people doing 70 are trying to get to the speed of traffic. It is the person merging into 70MPH traffic at 40 MPH is the problem. Instead of leaving a small hole get the he11 over.

RE: The source is pretty simple really
By mindless1 on 6/11/2009 2:08:38 AM , Rating: 1
Then you should have your license taken away as this is not safe driving and may incite retributional road-rage too. Thanks for making excuses to justify even worse driving conditions for the rest of us.

Oh BTW, thse people do not cause rear end accidents, rear end accidents are caused by those who follow too closely for the speed they are going or inattention, taking their eyes off the road for a moment. It is not the fault of someone driving too1 slow if they get rear-ended by someone else.

RE: The source is pretty simple really
By Spuke on 6/11/2009 12:13:29 PM , Rating: 2
quote:
It is not the fault of someone driving too1 slow if they get rear-ended by someone else.
I rear ended someone once when the traffic in my lane (right lane) suddenly stopped (panic braking). I swerved into the open left lane to avoid hitting the person AND to avoid the person behind me (too close) in front of me only to smack into a person stopped in the left lane who was trying to make a RIGHT turn!!!. This person caused the panic braking in the right lane. Who's fault was it? Mine AND the person I hit.

By mindless1 on 6/12/2009 1:45:09 AM , Rating: 2
NO!

If traffic in your lane slowed down and you could not slow down enough to STAY IN YOUR OWN LANE because of the speed and distance you chose, you are 100% AT FAULT.

This is FACT. It is taught in driver's school, is on driving exams, and is a point of law.

By afkrotch on 6/11/2009 4:36:14 AM , Rating: 1
FYI, I'd suggest not doing that. Ppl do get shot over stupid stuff like that.

RE: The source is pretty simple really
By keegssj on 6/10/2009 11:36:49 AM , Rating: 4
I was behind someone once who actually came to a complete stop on highway, and I watched as all four heads in the car turned to gawk at an accident.

I usually ignore it, but that driver got a full blast of the horn.

By nixoofta on 6/10/2009 12:32:03 PM , Rating: 2
Yeah,..those are looki-loo-itons. Previously known as rubberneckitons. MIT is working on a better name for them but as yet has come up emptyiton.

By Teancum on 6/10/2009 12:06:45 PM , Rating: 3
People forget that the "Acceleration Lane" is for ACCELERATING!!

By mikefarinha on 6/10/2009 12:26:59 PM , Rating: 2
Or more to the point...

Car's + Stupid People = Traffic

RE: The source is pretty simple really
By drycrust on 6/10/2009 1:31:18 PM , Rating: 2
True. One of the basic laws of physics is the speed of a car is less than or equal to that of the car in front.
As the density of cars on any given road goes up, the cushion between cars gets smaller. Since a car cannot travel faster than the car in front, when the car in front brakes or misses a gear change, the car behind must brake equal to or greater than the car in front.
As the average gap between cars gets smaller, so the need to brake harder than the car in front goes up. These two factors (speed car behind <= car in front, braking car behind >= braking car front) causes speed oscillations, which is really just classical wave theory. As with a normal amplifier, where the amplifying device cannot exceed its power supply's capability, so the traffic problems really start to happen when the physical bounds of the environment (speed limit or grinding to a halt) are approached.
This is why you get congestion around areas with merging traffic, because cars merging into a dense traffic stream with no extra lanes is just like an impedance mismatch. If the merging stream is also dense then really the only way to fix it without causing congestion is to have the merging traffic have their own lane.
However, it is important to note that if a line of cars is long enough, as happened when they were evacuating New Orleans, then you will get vehicle speeds that oscillate, which will cause vehicles to grind to a halt for no apparent reason.

By Xerstead on 6/10/2009 3:01:45 PM , Rating: 2
I was sure I'd seen a video of this effect before so i had a look and found one on YouTube:
This is like a mini version of the M25 motorway around London. This is one of the busiest roads in the UK and frequently has major traffic jams for miles. There is a variable speed limit around much of it indicated by overhead signs and speed camera enforcement. Traffic is slowed down at peak times to 40/50/60/70mph to help prevent and controll the problem.
The example is a circular road but it will have the same effect on a straight one.

By bpurkapi on 6/11/2009 1:33:25 AM , Rating: 2
People driving fast, slow, lots of people all leaving for work and leaving work at the same time. Solved! I'm in Taiwan right now(live in Portland,OR) and must say that USA traffic jams are shocking. Taiwan has smaller roads, and a whole lot more people on them, the difference is that they have a crap ton of motorcycles and scooters. The scooters travel in something similar to bike lanes in the states, and are allowed to split lanes. So what I'm trying to say is that here traffic jams are less severe even though the roads are much smaller, plus the cities are super dense so work is usually somewhat close to home, and commuter rail comes every 10-15 minutes. Its all about options, more modes of transport means its less likely to have horrendous traffic jams.

By Sunner on 6/12/2009 4:24:23 AM , Rating: 1
The source of many problems is that people see traffic as "A bunch of independent cars" instead of looking at it as one "organic" form.
Like cells and organs in a human body, every car affects the whole organic body of traffic, and if these cells or organs start shitting all over each other, the whole body will suffer as a result.
If the heart suddenly decided that "Fuck you brain, I'm not going to pump blood up to your lazy ass anymore!", things will soon be going south for the heart as well, same with assholes in traffic, they're just too stupid to realize it.

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