Take a look at this amazing video (via slashdot) showing how traffic jams can occur even when all the drivers are attempting to drive the identical speed.
As you can see, at first everything works fine -- the drivers have all been instructed to try to drive about 30 KPH. But almost inevitably everything goes horribly wrong. See this article for more details.
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It's not for no reason. It's because some assholes don't know how to drive without hitting the brakes for no fucking reason!
Living just outside Mexico City, I see this a lot as I commute to this huge metropolis every day. If this happens with 22 cars in a controlled area, imagine what happens in a city with over 20 million people! On top of that, people do not respect traffic signals, they drive on sidewalks, etc. The result? Street vendors actually sell saodas and snacks on the fast lane of the expressway!
Totally surreal!
Creating the circumstances in a laboratory -- the 22 cars circling for the camera -- was freaking brilliant.
Summary of lost comment: done in better video and more detail and full explanation by Garman TV station "3sat" www.3sat.de in their "nano" prog.
The reason why I won't explain it again here: I typed in a neat little summary, then hit , then got a message that there was an error in my e-mail address. No sweat I thought, I simply go back... guess what, my whole entry gone.
If you force people back because of anodine details like this, either keep the page alive and mark the missing entry in color or if they have to hit the back button, make sure their comment is still there else it's simply wasting your viewer's time and work. As is common practice all over the planet. Most irritating. Too intelligent to use common sense?
This *has* all been done before, by an amateur, on real roads.
http://www.eskimo.com/~billb/amateur/traffic/trafexp.html
He has also worked out how humans can fix the problem and shown it work on real roads without the need for robots.
His experience matches my 1st hand experience at squelching traffic waves. What he says works..
How surprising & unsurprising at the same time! (I believe the speed of the shockwave has something to do with average human reaction times)
This is definitely not a laboratory environment - too many variables and incidental conditions out of control here, but it IS just like real life - a couple of jerks, a couple of timid people, and everyone else, just trying to get there!
As I understand it, the way to avoid phantom jams like this is to ensure a decent separation gap between cars. Which I always try to do, except some numpty swerves in to occupy the gap I've left. >:-(
Back in my younger days I worked as a lowly dishwasher in a tea parlor on the street I lived on. I tried to explain this theory to my boss, who fequently complained of traffic jams for no reason, but she never got it. She proclaimed science was too hard and wave theory didn't make any sense and therefore couldn't possibly be the explanation. God how I wish I had this video to play to her back then!! Kudos to these scientists. Well done!
I find that video really stupid for several reasons. First and most striking, there was a NetLogo simulation, done like 10 years ago showing that this phenomena depends fully on the speed-up and slow-down rates. I really think that its a waste of time, money and resource to make 22 cars circle, just to show that traffic jams can form without obvious reason. Modeling guys....
Re: Ed's comment. That "numpty" who swerves in to take up the free space is a freeloader. Someone who is gaining a small personal benefit at a small societal cost. You should write about it ;)
@#$%@$% Japanese - they're all driving the wrong direction!
I think we've all suspected this for a long time. It just shows that there is a subtle rhythm to every thing we do and think.
At :09 seconds in you can see a white car (the one followed by a black car, an orange car, and another black car) slow way down and begin the shockwave. Probably talking on their goddamn cell phone! It's not for no reason- it's due to poor driving skills.
This is news? I am pretty sure this is standard homework fodder in all Civil Engineering courses on transportation. It was when I decided to take another fluids course instead of transportation.
I guess the "science" here is that they used a cheap video camera and put it on YouTube. Now it must be true!