An accident? Construction work? A bottleneck? No, just too much traffic

Mar 04, 2008

A new study from a Japanese research group explains why we’re occasionally caught in traffic jams for no visible reason. The real origin of traffic jams often has nothing to do with obvious obstructions such as accidents or construction work but is simply the result of there being too many cars on the road.

The research, published today, Tuesday, 4 March, in the New Journal of Physics, shows how model patterns, normally used to understand the movement of many-particle systems, have been applied to real-life moving traffic. The research shows that even tiny fluctuations in car-road density cause a chain reaction which can lead to a jam.

The research found that tiny fluctuations in speed, always existing when drivers want to keep appropriate headway space, have a cumulative effect. Once traffic reaches a critical density, the cumulative effect of gentle braking rushes back over drivers like a wave and leads to a standstill.

The researchers in Japan used a circular track with a circumference of 230m. They put 22 cars on the road and asked the drivers to go steadily at 30km/h around the track. While the flow was initially free, the effect of a driver altering his speed reverberated around the track and led to brief standstills.

Yuki Sugiyama, physicist from Nagoya University, said, “Although the emerging jam in our experiment is small, its behaviour is not different from large ones on highways. When a large number of vehicles, beyond the road capacity, are successively injected into the road, the density exceeds the critical value and the free flow state becomes unstable.”

The researchers will be advancing their research by using larger roads and more vehicles to further test their findings.

The research suggests that it might be possible to estimate critical density of roads, making it possible to build roads fit for the number of drivers needing use of it or, on for example toll roads, only allowing the right number of cars access to the road to stop mid-flow traffic jams.

Source: Institute of Physics

Explore further: What's fair?: New theory on income inequality

Related Stories

More cycling with e-bikes

May 20, 2015

According to a new study, electric bikes make people cycle longer and more often. The effect is best on women.

Spark electric car's price sparks a sales run

May 20, 2015

It took a price cut to generate a run on Chevrolet's 2015 Spark EV, with savvy car buyers realizing the lower price and federal electric vehicle tax credit can make for a super deal.

Recommended for you

Researchers prove magnetism can control heat, sound

1 hour ago

Phonons—the elemental particles that transmit both heat and sound—have magnetic properties, according to a landmark study supported by Ohio Supercomputer Center (OSC) services and recently published by ...

How researchers listen for gravitational waves

10 hours ago

A century ago, Albert Einstein postulated the existence of gravitational waves in his General Theory of Relativity. But until now, these distortions of space-time have remained stubbornly hidden from direct ...

What's fair?: New theory on income inequality

21 hours ago

The increasing inequality in income and wealth in recent years, together with excessive pay packages of CEOs in the U.S. and abroad, is of growing concern, especially to policy makers. Income inequality was ...

Scientists one step closer to mimicking gamma-ray bursts

May 27, 2015

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

whiskolafuerte
4 / 5 (1) Mar 04, 2008
Why would it not make a difference that they are experimenting on a circular track while we drive on long stretches of straight road?

Also, one can look at an accident causing increased traffic in the same way as the researchers: Say we build a highway with 4 lanes which is adequate to handle the traffic in the area in which it is built, but then an accident happens and two of the lanes are closed off, the proportion of cars to road space changes.

Ragtime
not rated yet Mar 04, 2008
Here's many traffic jam simulators on the web:

http://www.horstm...let.html

I cannt see nothing special or very new on the subject of article, as presented here.
superhuman
not rated yet Mar 05, 2008
Traffic is a real killer, its one of the most stressful experiences for me to drive a car!

It really pisses me off how much time is wasted in the traffic, especially when its due to ignorance and lack of foresight of other drivers, traffic jams, unsynchronized red lights and terrible road design and conditions where I live.
Skepticus
not rated yet Jun 06, 2009
Yeah, sperhuman, you are right all all counts. Take Melbourne, Australia for example, the antiquated trams ride on tracks built in the same lane of motor vehicles. By laws, when the tram stops for passengers getting on and off, the cars must stop behind it and wait. Add to their slow speeds, frequent stops, and tram-train crossings, where the train and trams cross them with walking pace to avoid derailing...throw in 2 trams and 2 train crossing at rush hour at the same time, and you get get the unholy mess 5 city block long!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.