Traffic jams without bottlenecks—experimental evidence for the physical mechanism of the formation of a jam

The mathematical theory behind shockwave traffic jams was developed more than 20 years ago using models that show jams appearing from nowhere on roads carrying their maximum capacity of free-flowing traffic - typically triggered by a single driver slowing down. After that first vehicle brakes, the driver behind must also slow, and a shockwave jam of bunching cars appears, traveling backwards through the traffic. The theory has frequently been modeled in computer simulations, and seems to fit with observations of real traffic, but had never been recreated experimentally until recently (PDF of SCIENCE). The authors also released video of their experiments which has since been posted to YouTube. [more inside]
posted by Blasdelb on Mar 24, 2012 - 42 comments