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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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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>


"So if you want to save the planet, feel free to drive your Hummer. Just avoid the drive thru line at McDonalds." -- Michael Asher











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