What is the zipper merge? Illinois law brings technique to highways, rulebook

CHICAGO (WLS) -- What's the proper way to merge when lanes are reduced in a construction zone, or when emergency vehicle block a lane? Move over early, well before the pinch point, right? Wrong.

There's actually a better, safer way called the zipper merge, or late merge, and it's the opposite of what we've been doing all along.

Most people aren't familiar with the zipper merge and have never even heard of it. But with construction season just a couple months away, the Illinois Department of Transportation wants drivers to use the zipper merge technique when approaching lane closures.

"What we're looking for people to do is fill in both lanes all the way up to the merge point, lane closure point, where the lanes reduce down to a single lane," said Matthew Daeda, IDOT traffic operations engineer. "At that point the motorists will then have to take turns."

Experts believe that is the quickest way to get through construction sites and entrances on highways during busy season.

So much so that a new law for 2020 mandates the zipper merge be included in this year's Illinois Rules of the Road handbook, following many other states that already use the technique like Minnesota, Missouri, North Carolina, Montana and Nevada, to name a few.

In fact, Germany has been using the reibverschlub since 2001.

According to a 2013 Minnesota study, using the zipper merge reduces the length of traffic backups by as much as 40%, reduces congestion, creates a sense of fairness with everyone moving at the same speed, and reduces road rage.

Not only is the zipper merge a safer and more efficient way to merge into traffic, it's the law and carries a $164 fine, not including court costs and fees.

"The law specifically states that each driver shall reduce speed and or position to allow a person to actually merge," said Sgt. Delila Garcia, Illinois State Police.

The challenge is to re-train drivers to merge late when, to many, that feels like cheating.

"You're right, it is a lot like people cutting in line in front of you and a lot of people don't like cutters," said Daeda. "We're kind of doing a lesson learned from what the other DOTs are experiencing with all these zipper merges, and we're gonna try and take what's best and what's working with those DOTs and apply it here."

"It's like anything else," said Dave Drucker, spokesman for the Illinois Secretary of State. "It's a matter of time, and for people to learn."

"I think if people do it properly, it works," said Pat Higgins, driver.

"I think there has to be a change of attitude, where you don't treat other drivers as the enemy," said Scott Skaletsky, driver.

There will definitely be a learning curve.

One of the first places you'll see the zipper merge put into use will be this spring, when construction starts up again on I-55 at Arsenal Road in Will County. Last year there was a big problem with semis straddling the lanes to prevent traffic from merging closer to the pinch point.