First a little background.
As you may know, I live in eastern Massachusetts, where four lanes in one direction is considered a superhighway (seems odd, I bet, to you folk in LA and Atlanta). And many busy suburban roads are only one lane in each directionwhich keeps with the New England scenic character and you can admire the country as you sit in rush hour traffic.
On a four lane road I avoid the left lane because the drivers there don't know how to drivethey're too fast and too close together. As a result, when one slows or brakes, the traffic stream "compresses" and often stops. Thus the lane adjacent to the far left one averages a higher speed, but with lower peaks and without the stops.
Now our friends at Autoblog have found a video from Japanese researchers that shows this traffic "shockwave" effect in action (Click, then scroll down for the link).
One solution to ease such traffic fits and starts would be to have a critical mass of cars be quipped with adaptive cruise control, which would keep these "trains" of cars moving consistently, with less stress on the drivers and some likely fuel savings as well.