Understanding zipper merge can save highway headaches in Omaha-metro

OMAHA, Neb. (WOWT) - Go with the flow is often good advice when it comes to traffic unless you don’t understand “the flow” in congested construction areas like the U.S. Highway 75 south of I-80.

If you travel U.S. 75 in or out of Omaha to the south, you’ve been feeling the pain. A long stretch of construction, expected to continue for a few months, requires narrowing to one lane.

In cases like this, the Nebraska Department of Transportation often puts in place a traffic strategy known as the zipper merge. And nothing seems to confuse motorists in the Metro more than the zipper.

”The zipper merge is safer, it’s faster, it allows people to occupy both lanes at a slow speed and not congest everything that’s behind them,” Sarpy County Sheriff’s Lt. Chris Teuscher said. “I think complete stops are what get people frustrated, so if you can do the zipper merge properly, everyone keeps rolling, patience is kept in check, and everybody gets home safely.”

Essentially, the zipper asks motorists to slow down and remain moving in both lanes. There is a solid white line indicating no mergers. As the slow traffic gets closer to the merge point, drivers are then asked to take turns, one at a time, merging into one lane.

”Patience is the key,” Teuscher said. “So when you’re coming up on that, it’s just gonna take a few seconds extra to allow that person on your left or right to merge in front of you, to be on your way.”

Nancy Singer of the Federal Highway Administration said significant research has been done in this area that shows the ‘late merge’ or zipper technique actually works. That research shows the zipper merge can indeed reduce backup and even reduce road rage. But there’s one big ‘if’. It only works if drivers follow the directions. The FHWA says the concept is based on the “go slow to go fast” principle.

“Go slow to go fast” is a seemingly paradoxical idea that, if we slow down the rate of our “mixing,” we can get past a constriction faster. A well-known example is the “rice experiment.” In the first case, dry rice is poured all at once into a funnel. In the second case, the same amount is poured slowly. Repeated trials generally conclude about a one-third time savings to empty the funnel via the second method.

Frustration over what some perceive as cars “cutting in line” comes as a result of simply not being clear about what zipper merging means. Teuscher said a little understanding of the zipper merge can reduce stress as well as traffic incidents.

“If you fill up both lanes and zipper merge, then you’ll get through a lot quicker, there’s no stopping or starting,” Teuscher said. “If you don’t zipper merge, that one lane that does have thoroughfare...will back up and potentially cause accidents on the freeway (and) the road they’re coming off of.”

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