Galactic_grub writes "Japanese researchers recently performed the first experimental demonstration of a phenomenon that causes a busy freeway to inexplicably grind to a halt. A team from Nagoya University in Japan had volunteers drive cars around a small circular track and monitored the way 'shockwaves' — caused when one driver brakes — are sent back to other cars, caused jams to occur. Drivers were asked to travel at 30 kmph but small fluctuations soon appeared, eventually causing several vehicles to stop completely. Understanding the phenomenon could help devise ways to avoid the problem. As one researcher comments: 'If they had set up an experiment with robots driving in a perfect circle, flow breakdown would not have occurred.'"