01-31-2011, 11:59 PM
I've never seen a "zipper merge" sign, but the L R L R method at the point of merge does work best in my experience.
On Houston freeways, on weekends, you can see what happens when people get in line early. There is typically a line of 30-50 cars at a backing up exit ramp, and those cars at the end of the line can take more than 30 minutes to get off the ramp. What's happening is that people drive by the line and cut in line near the front - so much so that about 80% of the cars getting off the ramp are cars that have cut into the line. So, the people in back who don't do the cutting in line wait while people cut in front of the people who have cut in front... 1-2 minutes to get off if you cut, 30+ if you don't. Wonderful choice, at a glance it looks like most people don't cut, but watching it long term, you can see that most people do, in Houston.
At a 2 lane merge, you can attempt a "vigilante save" of the early mergers by staying in the empty lane at the end of the line, preventing people from cutting by just staying with the person who was there before you - this works with moderately aggressive traffic, but extreme yahoos will go around you on the shoulder...
Better still if everyone would just choose the shortest line until the dividing line is gone.