Emergent Traffic Chaos
Paul Kedrosky has an amazing video:
As described in the New Scientist:
Researchers from several Japanese universities managed the feat by putting 22 vehicles on a 230-metre single-lane circuit (see video).
They asked drivers to cruise steadily at 30 kilometres per hour, and at first the traffic moved freely. But small fluctuations soon appeared in distances between cars, breaking down the free flow, until finally a cluster of several vehicles was forced to stop completely for a moment.