Do You Zipper Merge?

zippermergecropWhile driving back from Indianapolis last Sunday, I started noticing cars pull over into an increasingly congested left lane. I followed suit, thinking they had seen something ahead in the right lane.

Traffic quickly drew to a halt in the left lane, with right lane wide open. So after a few minutes, I inched over there far enough for some of my passengers to scout ahead. They confirmed that there was nothing at all in the right lane, at least not for quite some distance.

We proceeded to debate what to do. I recalled an article a few years ago that said that everyone benefits in thick traffic if each driver pursues their own best interest until the very end of the line, where you are do perform a zipper merge (cars from each lane alternate moving forward). This is especially the case in an extreme example like what was happening on Sunday–hundreds of cars were using 1 lane even when 2 lanes were available. So I proposed we move into the right lane and proceed, hoping others would follow our example.

The counterargument–the one in favor of staying in the left lane with all other cars–would, as my copilot said, make us look like dicks. (Pardon my language.)

So that was the dilemma. We chose not to draw the ire from all of the left lane cars, and we stayed in our place. However, when we got back to St. Louis, one of my friends learned that the Missouri Department of Transportation actually recommends that we be dicks and use the zipper merge in the exact situation we encountered.

What do you think? What would you have done?

6 thoughts on “Do You Zipper Merge?”

  1. To use your terminology, I am pretty much always the “dick”. I drive I-5 in WA State up North from Seattle regularly to visit family, and there has been a ton of construction recently between exit 192 and 210. In many of the areas they block off the left lane and force everyone into the 2 right lanes.

    I drive right up to the cones and zipper merge last second. I regularly get honked at and occasionally have a few drivers try to bumper-to-bumper block me from merging, but after growing up in Chicago and driving the loop, I learned that there are very very few drivers that will actually block you when push comes to shove.

    The question I am always left with is what to do after the zipper merge. Usually, everyone in the merged lane is still freaking out, so I hop into the other lane and can jump ahead of 5 to 10 cars in the merged lane before traffic gets back to normal speed, then I hop back into the left-most lane and continue with the flow from there.

    But then again, I am impatient in general…

    • Anthony: Thanks for sharing! I think the key is that it’s mutually beneficial for everyone if they pursue that strategy, so they shouldn’t hold it against you.

  2. I think the problem is awareness. If its an accepted system then you are not being a dick. If you put it as part of Drivers License exams gradually the public will learn about it, which is what is happening in Missouri and other states. I have one near where I live where it is a zipper merge left turn lane. Generally there is enough spacing between cars turning left that zipper can happen, and others need to turn right ahead in a half mile stretch that it works out.

    I think it goes back to our idea of lines, especially the way the UK treats queues. If everyone knows its expected, then there is less road rage about it. Without that knowledge it gives the same feeling as someone is cutting in line.

    • Sean: That’s a good point, it should be taught as part of the driver’s license program if it’s the official accepted way.

  3. I think the question with “zipper merging ” is more about if you effectively merge in relation to when lane completely ends. When you can see the sign that makes you aware that the lane will be ending most reasonable people will start to look for an opening in the lane and merge, doing your best not to cause the person you are merging in front of to have to slow to the point of stopping.

    For me when it is clear that someone is aware that the lane they are in is ending and they don’t take advantage of a space that I am leaving in front of me while they are moving, once they have reached the end of their lane and are stopped I don’t feel bad not proactively slowly or stopping to make space as it would effect not only me be potentially everyone in the lane behind me.

    So sure zipper merge, just do your best to do it in a way that doesn’t adversely effect the other cars around you.

  4. I wished we did without having someone blocking us to do so. This car in front of us was driving on both lanes so no one can pass. Our “race car” driver had a sudden deceleration and did a couple mini swerves to tease the front car, they did the same to continue to block. My nap was disrupted by this and a bit scared, but the rest of the ride was filled with K-pop girl band music.


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