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What is zipper merge and how does it work?

Question: Could you explain the Zipper Merge for merging into construction zones in Minnesota? I have tried using the Zipper Merge many times and it seems that hardly anyone else on the road knows about how it is supposed to work. If another driver intentionally blocks a lane, isn't that against the law?

Answer: According to the Minnesota Department of Transportation, when a lane is closed in a construction zone motorists should use both lanes of traffic until reaching the defined merge area, and then alternate in "zipper" fashion into the open lane.

Some drivers slow too quickly and move to the lane that will continue through the construction area. This driving behavior can lead to unexpected and dangerous lane switching, serious crashes and road rage.

It is suggested that when you see the "lane closed ahead" sign and traffic backing up, stay in your current lane up to the point of merging. At that point, take turns with other drivers to safely and smoothly ease into the remaining lane. When traffic is heavy and slow, it is much safer for motorists to remain in their current lane until the point where traffic can orderly take turns merging.

Studies show that the "zipper merge" works the best to keep traffic flowing, especially when there is a lot of traffic, by:

• Reducing differences in speeds between two lanes.

• Reducing the overall length of traffic backup by as much as 40 percent.

• Reducing congestion on freeway interchanges.

• Creating a sense of fairness and equity that all lanes are moving at the same rate.

The "zipper merge" also helps prevent road rage from drivers who intentionally go slow in the lane that is closing, and blocking other drivers from passing or getting through. That is against the law. Lane blocking or impeding traffic fines are approximately $139.00 and the offense goes on your driving record. We are watching out for lane blockers in all situations. To watch a video on how to use the zipper merge go to

A portion of state statutes were used with permission from the Office of the Revisor of Statutes. If you have any questions concerning traffic related laws or issues in Minnesota, send your questions to Trp. Jesse Grabow — Minnesota State Patrol at 1000 Highway 10 West, Detroit Lakes, MN 56501-2205. (You can follow him on Twitter @MSPPIO_NW or reach him at,