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State Studying 'Zipper Merge' to Help Reduce Congestion at Emerald Isle Bridge

Greenville - Researchers at North Carolina State University say a new traffic treatment called a "zipper merge" has the potential to reduce backups by as much as 50 percent. The state transportation department is working with N.C. State to determine if this new style of merge can be successful on N.C. 58 just before the bridge over to Emerald Isle in Carteret County.

The "zipper merge" encourages drivers faced with lane closures to work together and take turns where the lanes merge, not only to reduce congestion for all vehicles, but also to improve safety.

"While this goes against the grain of what we like to do as drivers, the zipper merge allows both lanes to be used to their full capacity," said Kevin Lacy, state traffic engineer. "With a little extra courtesy, we could greatly reduce the length of traffic jams, decrease travel times and increase safety."

The DOT is installing signs today directing drivers to follow the zipper merge pattern. The signs ask drivers to stay in their lane until they reach a specified point. They then follow the directions of signs to make the merge. Drivers in the open lane are asked to take turns allowing vehicles from the closing lane to merge in front of them as depicted in the accompanying graphic.

Engineers with N.C. State studied backups at the bridge over a two-week period in May and June that included the Memorial Day holiday. They will compare that data to the data they observe over the next two weeks to determine whether the "zipper merge" was effective at changing driver behavior to reduce delays and increase safety.

Michigan and Minnesota are among several states that have implemented the zipper merge and have been able to greatly decrease the length of backups and create safer, smoother driving conditions.

"One zipper merge site in Michigan saw congestion reduced from 6 miles to 3 miles," said Chris Vaughan, research associate with N.C. State's Institute for Transportation Research and Education. "The time spent in traffic also decreased dramatically at this site, saving drivers an average of 15 to 25 minutes. This is predicated on compliance, meaning that cooperation with other drivers is the only way this will work. While this seems daunting, we are confident that a little southern hospitality can go a long way."

The zipper merge will be installed at other locations this summer, including I-85 South just past the N.C. 147 interchange in Durham. The other sites have not been determined.

During congested periods, NCDOT urges drivers in the merge area to be extra courteous to other drivers and understand that those in the closing lane are not simply trying to "cut in line" in front of drivers in the open lane.

"By taking turns, you are all, in fact, helping everyone's travel time go down," Vaughan said. "Please remember that by working together, your travel time and safety will improve, as will everyone else's around you."

For real-time travel information at any time, visit the Traveler Services section of the NCDOT website or follow NCDOT on Twitter.


4/16/2018 4:30 PM