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Traffic Sim Predicts Jams Before They Happen
Via_Patrino writes "The New Scientist reports that: A traffic simulation system is helping drivers by predicting jams up to an hour before they happen. Traffic flow can be divided into three categories: freely flowing, jammed, and an intermediate state called synchronised flow in which dense traffic moves in unison. Physicists at University of Duisburg-Essen have developed 'the first model to reproduce all known traffic states.' Predicted conditions are displayed on the official website, and more than 90 per cent of the time, traffic density is predicted correctly."
What if people start using it? They avoid the traffic jams, thus no traffic jams. Wrong prediction!
I remember a few years ago being told by a teacher that traffic flowing under 28mph on Motorways obeys hooks laws for compression waves travelling through a spring almost perfectly...
The compression waves travelling through the traffic are the reason that everything goes stop/start once traffic slows below a certain speed...
Karma: -2147483648 (Mostly affected by integer overflow)
An idea borrowed from quantum mechanics...
Measuring the system changes the system.
What if everyone takes the same alternate route to avoid the "busy" route?
As the story points out:
"But the website has already become a victim of its own success, admits Schreckenberg. Some of the 300,000 people a day who are visiting the site are replanning their journeys on the basis of its forecasts, and this is beginning to make the forecasts themselves less accurate."
There were and are several projects in Germany that develope traffic models in conjunction with models simulating the route choices of people depending on their lifestyles. The problem is that there are people that do not believe that people can be simulated by cellular automata and reject those simulation. But there are also city planers who use those models when planning new structures like stadiums, airports and others that need road connections.
There is a sourceforge project thatsimulates multimodal traffic with cellular automata. Also have a look at this link for more information about traffic simulation.
***Quis custodiet ipsos custodes***
I believe the algorithm was leaked a few days ago:
// double jam sandwich
if ((time == 8am-ish) || (time == 5pm-ish))
double jam =1;
if (city == LA)
long long jam = 2^64;
I drive a stickshift and consequently cannot stand stop n' go traffic on a freeway. So I even it out and am able to maintain a consistent speed regardles of the sporadic flow ahead of me. This of course pisses off the person behind me because I have "too much space" in front of me. They usually don't realize that I'm doing them, their car, and their gas mileage a favor. I wish people would just think about these things. The easiest lane to be in in this type of traffic is usually the lane with all the trucks, as they too cannot stand the constant shifting and braking of stop n' go traffic.
Libertarian: label used by embarrassed Republicans, longing to be open about their greed, drug use and porn collections.
Use the "effects" of the prediction to get the desired results. For example, if you want clear sailing on Route 9 going north at 4:00pm, predict bad traffic ahead of time.
If you want more predictable traffic patterns, fudge prediction differences downwards so that less people will take action based on the predictions.
It's all one big feedback loop, dampen accordingly.
In 1998 William Beasley posted a paper on Traffic Waves in Seattle, subtitled "SOMETIMES ONE DRIVER CAN VASTLY IMPROVE TRAFFIC".
The site has great animations and excellent explanations of the impact of different drivers actions on the overall flow.
Worth a look: Traffic Waves