“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.”
http://technology.newscientist.com/article/dn13402-shockwave-traffic-jam-recreated-for-first-time.html
http://technology.newscientist.com/article/dn13402-shockwave-traffic-jam-recreated-for-first-time.html