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."

Comments

What if people start using it?

[Zebidiah]

What if people start using it? They avoid the traffic jams, thus no traffic jams. Wrong prediction!

Re:What if people start using it?

[mphase]

Good point. It only applies if a large portion of the potential traffic was aware of the prediction but still a good point. It's not a matter of being a right or wrong prediciton though, it's a matter or decreasing traffic. If it makes it so people get stuck in traffic less than it is a success. The statistic of being "right" or "wrong" in its prediciton is pointless. Though obviously if every damn person was aware of it the predicted traffic would become the perfect driving conditions because everyone would avoid that area. So then people would start to purposefuly drive in the areas the system said would have heavy traffic, knowing that everyone else would avoid it. But then because so many people did that there would be traffic and so people would learn to avoid the areas...repeat until you come to the topic of a land war in China.

Hooks law

[Anonymous Coward]

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...

A note

[pyth]

For those people concerned that releasing the predictions will interfere with the results, please remember that not many people will actually use this tool.

This is one of my pet peaves

[rsilvergun]

I hate seeing people speeding to red lights, when if they'd just follow the flow of traffic and the lights they'd get where they're going just as fast, and without causing traffic jams. I'm a terrible driver, but I figured this simple thing out pretty early on. Why can't the rest of drivers?

Re:This is one of my pet peaves

[willpall]

Or a corollary to that:

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.

Re:What is the cause?

[skraps]

And if everyone reads when there will be a jam, no-one will drive then, and the traffic jam will be at a different time.

Presumably, this is a closed-loop system, with a short loop. The predictions are based on very recent, near real-time data. If the traffic is affected by people reading the predictions, then the predictions would adjust to compensate very quickly.

Measuring Theory Of Traffic

[uncreativ]

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."

Re:Pre-emptive analysis?

[mocm]

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.

Here's the algorithm they use:

[phandel]

I believe the algorithm was leaked a few days ago:

if ((time == 8am-ish) || (time == 5pm-ish))
double jam =1; // double jam sandwich

if (city == LA)
long long jam = 2^64;

They just need to take this into account...

[ebyrob]

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.

Re:Synchronized flow isn't stable

[jrumney]

The density of traffic would be lower because the traffic is flowing more smoothly, not because less cars are using the road. This is a good thing.

Traffic Waves - research and animations

[WRXFiles]

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

Re:What is the cause?

[Bozdune]

Right.

Note that this system is infinitely better than the radio "traffic reports," like those in Boston on 1030 WBZ. The announcers already know from experience where all the slowdowns are likely to be, so they just repeat the same B.S. every morning, true or false, until they get lucky and their helicopter spots something, or the State Police radio in an accident.

I used to commute the Mass Pike eastbound from 495 into 128/95, and I can count on the fingers of one hand the times that the "traffic report" was actually accurate.

As far as people paying attention to the web site and changing their route based on 30 minute or 60 minute advanced prediction, thus screwing up the "prediction," that's only an issue if you need advance warning before you leave the house. What's really needed is a real-time decision when you come up against a junction point. Which way? Tell me now. Should be easy enough to do with a real-time feed from your car to the model.

Not that there's that many obvious alternate route choices around Boston anyway, but it sure would be helpful to have precise information on the jam-ups for those of us who know the back roads.

Traffic Waves

[pipingguy]

See also this site.

Have you ever been driving on an interstate highway when traffic suddenly slows to a crawl? You inch along for many minutes while waiting to see the accident which must have caused the jam. At the same time you also curse the "rubberneckers" who are causing the whole problem. But then all the cars ahead of you take off at high speed. The jam is over, but no accident, no police cars, nothing. WHAT THE HECK WAS THAT! A traffic jam with no cause? In the rear-view mirror you see all the poor saps behind you still stuck in the jam. But why? If all those people could just speed up at the same time, the whole traffic jam would evaporate. Why don't they ever do that? What caused the mysterious slowdown in the first place?