This question is a bit of a long shot for this site but it is psychology-related so I thought I'd give it a try. This is a little thought exercise.
I was driving down the expressway toward downtown Chicago this afternoon, frustrated at the gridlocked traffic. I thought to myself "wouldn't it be great if the people that were going to get off on an exit soon drove in the far right lane while those that would be driving a long distance drove in the far left lane." This way we'd be able to maximize speed for those that are passing through and avoid the delays of weaving in and out of traffic for the short distance drivers. Unfortunately people don't do this, we look at the lanes as fast or slow.
In order to help "stratify" the drivers instead of a big weaving blob, I wondered whether or not something like a sticker on the back of the car where the color of the sticker was associated w/ how far you had to drive from the city center would work. When people act as a herd, would something like function as a little trigger? If a person was a "red" and saw other red drivers, would that kind of mark push the driver to say, "those people are going where I am going. I will model my driving speed/lane selection after theirs." I know that this depends on the individual. Could we use herd behavior to an advantage?