While I’m on the topic of traffic flow, there’s some yummy content on this site: Physics for Bored Commuters. Mr. Beaty confirms some of my suspicions about how to make traffic run more smoothly, most notably the idea of leaving a large space in front of your vehicle for merging traffic. Beaty also links to a slick Java applet that simulates a small area of in-town stoplight traffic that you can manipulate. (thanks Aaron and Peter)
One thing that he didn’t mention is the proper speed of a merging car. In order to merge successfully into moderate-to-heavy traffic, you need to be moving at least as fast as said traffic. Failure to do so results in a traffic pileup both on the on-ramp and on the highway.