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Merge now or later? I-40 lane closures delay traffic at TN/NC line

Drivers on Interstate 40 will deal with one-lane traffic at the state line of Tennessee and North Carolina through May 2020. When is the best time to merge?

COCKE COUNTY, Tenn. — Drivers on Interstate 40 continue dealing with delays near the state line of Tennessee and North Carolina. Traffic is down to one lane in each direction through May while North Carolina crews build a new five-mile stretch of median wall.

The construction is in North Carolina, but eastbound lane closures begin in Tennessee. So do traffic snarls.

"Unfortunately, we've seen during peak travel times some of these back-ups happen a few miles into Tennessee," said Mark Nagi with the Tennessee Department of Transportation (TDOT). "We try to give drivers as much advance notice miles ahead of time so they know to expect delays."

During a prolonged backup Saturday, roadside signs included a message for drivers to "use both lanes to merge point."  The message goes against many drivers' natural instincts to merge into one lane as soon as possible.

Credit: WBIR
Sign indicating the right lane of I-40 is closed as drivers approach the North Carolina state line.

Waiting to merge can also upset drivers who perceive the practice as cutting in line.

"It's insanity. Everyone waits until the last second to get over, although you're warned with four miles to merge. It's ridiculous. And it creates pandemonium," said Ronnie Steafford, who commutes back and forth from North Carolina and Tennessee.

The anger at drivers who wait until the last second to merge is the stuff memes are made of.  A popular meme states, "You'll hit every cone on the highway before I let you merge in front of me because you saw that sign two miles ago just like I did."

But the driver who seemingly procrastinates may be doing the correct thing. Traffic experts in many states, starting with Minnesota, have started public awareness campaigns to convince drivers to "zipper merge."

VERIFY: Oct. 26, 2017 - Should you zipper merge or not?

Zipper merge means drivers should proceed in both lanes until closer to the merge-point. When the lane ends, vehicles should alternate allowing each car to merge. The effect is similar to the teeth of a zipper coming together into one path.

Credit: WBIR
Graphic illustrating the zipper merge technique where drivers alternate and take turns merging two lanes into a single path.

When cars merge too soon, it creates one long slow line of traffic.  Two shorter lines of traffic that cooperatively merge can help traffic zip through work zones faster.

Despite overwhelming expert evidence the zipper merge is a more effective way for traffic to flow, many drivers are unconvinced.  Steafford is one of them. He has no intention of letting someone merge at the last moment.

"Absolutely not. If you're dumb enough to wait until the last second, you can stop and wait for some idiot behind me to let you in. Have you ever seen a broken zipper? It doesn't work. Get your rump over before it is time to merge, guys. It just makes sense," said Steafford.

RELATED: Jan. 6, 2020 - rehabilitation project restricts I-40 to one lane near North Carolina & Tennessee state line

RELATED: Jul. 6, 2018 - Zipper merge will upset other drivers. Why you should do it anyway.

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