THE ZIPPER MERGE.

August 11, 2008 at 10:48 AM · Uncategorized

THE ZIPPER MERGE. Cynthia Gorney had an article in the New York Times Magazine for August 3 about the traffic problem that occurs when three lanes of traffic must become two. Usually an immense traffic jam occurs. What is the best way (in terms of maximum vehicle flow) for the lanes of traffic to merge? The key is that it is stops and starts which cause traffic delays, and battles between drivers for right of way cause stops and starts. The ideal merge has the technical name of a “zipper merge”, where cars smoothly take turns. (Compare the same metaphor for the Zipper Theorem, which deals with the intermeshing of two mathematical series).

4 comments

Annalisa August 16, 2008 at 12:37 AM

I had the privilege of being taught how to drive, in large part, by Pater Familias. When it came time to merge, I was already zipping along the Merritt Parkway (an old, two-lane highway in Connecticut). I asked him urgently how to merge. He replied calmly, “Oh, they sort themselves out.” This did not make me feel calm at all, but as it turned out, I didn’t get in an accident or anything so I suppose it was good advice. Since then I have done plenty of merging and have decided that the main thing that throws a wrench in Dad’s theory is when people speed up or slow down to an extreme degree, which throws off any predictions you’ve made already.

Lee November 4, 2010 at 11:26 PM

Drew Barrymore was on The Daily Show discussing her road rage recently and Jon Stewart held up a successfully executed zipper merge as the hallmark of civilized motoring.

Nick December 15, 2010 at 2:18 PM

In terms of highway merging, I was taught largely by the Sears Driving Academy (I often asked if that made me a Driving Cadet) – and they told me two pieces of very valuable information in terms of merging.

1) To rely on my side mirror quite a bit instead of trying to turn my head for an extended period of time.
2) When I’m on the highway, that the best way for cars to be able to merge around you is to maintain your speed. Ideally you can just change lanes to make the space for them, but it’s easier for entering drivers to predict your movements if they’re constant.

Dick Weisfelder December 15, 2010 at 2:27 PM

Think how often vehicles have already merged only to find hot shots passing up to the very last possible point and slowing everything down. I like it when truck drivers deliberately serve as monitors and block them. The merge is usually quicker as a result.