Because we haven't argued about traffic and driving habits for a while now...
Scientists in Japan have
recreated the shockwave traffic jam in a laboratory setting (link has video). According to the story:
Traffic that grinds to a halt and then restarts for no apparent reason is one of the biggest causes of frustration for drivers. Now a team of Japanese researchers has recreated the phenomenon on a test-track for the first time.
The mathematical theory behind these so-called "shockwave" jams was developed more than 15 years ago using models that show jams appear from nowhere on roads carrying their maximum capacity of free-flowing traffic – typically triggered by a single driver slowing down.