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: New filter could advance terahertz data transmission

add to favorites email to friend print save as pdf

Related Stories

Who needs a hybrid when there's a diesel Jetta?

Feb 18, 2015

For 2015, Volkswagen's best-selling vehicle, the Jetta compact sedan, builds on its fine road handling character and adds a nicer interior, freshened front and rear styling, new safety features and a more fuel thrifty diesel ...

Recommended for you

New filter could advance terahertz data transmission

Feb 27, 2015

University of Utah engineers have discovered a new approach for designing filters capable of separating different frequencies in the terahertz spectrum, the next generation of communications bandwidth that ...

The super-resolution revolution

Feb 27, 2015

Cambridge scientists are part of a resolution revolution. Building powerful instruments that shatter the physical limits of optical microscopy, they are beginning to watch molecular processes as they happen, ...

A new X-ray microscope for nanoscale imaging

Feb 27, 2015

Delivering the capability to image nanostructures and chemical reactions down to nanometer resolution requires a new class of x-ray microscope that can perform precision microscopy experiments using ultra-bright ...

Top-precision optical atomic clock starts ticking

Feb 26, 2015

A state-of-the-art optical atomic clock, collaboratively developed by scientists from the University of Warsaw, Jagiellonian University, and Nicolaus Copernicus University, is now "ticking away" at the National ...

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.