GOLDEN VALLEY, Minn.- It is a question Minnesota motorists have grappled with, debated and even argued over for decades: Are drivers who blast past stopped traffic up to the point a lane closes obnoxious and rude, or simply doing what they're supposed to?

In traffic circles it's called the zipper merge, and KARE 11 gets questions about it all the time. To finally answer the question, are drivers supposed to do the zipper, KARE 11's Alicia Lewis went to the Minnesota Department of Transportation (MnDOT) where she spoke with Ken Johnson, an engineer and traffic expert who's been studying the "Zipper Merge" for more than a decade.

To get everyone up to speed here is a refresher on what the zipper merge is, according to MnDOT.

"When a lane is closed in a construction zone, a zipper merge occurs when motorists use both lanes of traffic until reaching the defined merge area, and then alternate in "zipper" fashion into the open lane."

In fact, MnDOT has been studying the effects of the Zipper Merge since the early 2000's.

"At the time it was still called the "Late Merge" and so we felt that there was this thought that late means bad, and there is a negative connotation with that, and at that time we changed it to the zipper merge to help people be aware because we want people to take turns," recalled Johnson.

"By using the zipper merge, the benefits are that you reduce that backup by close to half because you are using both lanes as opposed to one lane its half the distance," Johnson explained. "In addition, we are also able to get the traffic flow to be even between both lanes."

In other words, MnDOT VERIFIES that drivers are supposed to use the zipper merge when two lanes of traffic funnel down to one, but they're still not getting the message. According to research, 80 percent of Minnesotans opt to be early mergers and two-thirds of early mergers would not be happy letting the so-called 'later mergers' into their lane.

Really, this isn't a new concept, in fact it's a simple one. In Kansas, the Department of Transportation there is using cartoon traffic cones to explain why zipper merging is effective.

"The zipper merge concept has been put into the drivers manual so our kids learning how to drive 15, 16 year- olds are learning about the zipper merge and it's just going to be part of their culture," said Johnson.


Ken Johnson, MnDOT Traffic Engineer