Researchers from the Nagoya University are researching why traffic jams can occur for no reason. The phenomenon is known as a shockwave traffic jam. In the video below the Japanese researchers setup an experiment where 22 cars were instructed to travel on a circular course at 30 kilometres an hour. Small variances in speed between each vehicle caused the distance between each vehicle to decrease which causes trailing vehicles to slow down in order to avoid collision, this flows on down through the chain of vehicles and eventually the speed is so slow that vehicles are stopping to avoid collision with the vehicle in front.

From the experiment it could be argued that on highways and freeways where the road geometry is of a standard where it is to safe to travel above the prescribed speed limit that the legal enforcement of the speed limit is causing congestion through the shockwave traffic jam effect, and increasing the risk of of nose to tail collisions.