English transcript

For the first time, Japanese researchers have

conducted a real-life experiment that shows

how some traffic jams appear for no apparent

reason. They placed 22 vehicles on a single

track and asked the drivers to cruise round

at a constant speed of 30 kilometers an hour.

At first, traffic moved smoothly, but soon the

distance between cars started to vary and vehicles

clumped together at one point on the track.

The jam spread backwards around the track like

a shockwave at a rate of about 20 kilometers

an hour. Real-life jams move backwards at about

the same speed.