'Zipper merge' designed to ease congestion stumps Tucson drivers

Since construction began in the area of Kolb and Valencia roads, snarled traffic has become the norm, but officials are hoping a different merging technique will ease the congestion.

The bad news: Some, if not most of us, are doing it all wrong.

When a lane is closed during construction, motorists traveling southbound on Kolb should use both lanes until reaching the posted merge point, then alternate merging into the travel lane like a zipper being pulled up — hence the name “zipper merge.”

It’s being used in the city’s road-improvement project to widen Valencia Road between Kolb and Wilmot roads. Construction is set to finish next summer.

As heavy traffic was slowing down to merge near the Valencia construction, city officials determined something needed to be done.

Traffic officials were seeing significant backups due to motorists merging into the left lane too soon and decided to try the zipper merge, said Michael Graham, a Tucson Department of Transportation spokesman.

But when asked if officials have seen reduced traffic times, Graham said “No.”

“The majority of people aren’t utilizing the merge,” Graham said. “From what we’ve learned from the Arizona Department of Transportation is that it’s effective when people utilize the zipper merge. It works — it’s the idea of now getting people in Tucson to think about trying that zipper merge.”

Permanent signs were made by TDOT after electronic message boards appeared to be ineffective. Now those permanent orange regulatory signs line the side of southbound Kolb, letting drivers know to keep going before they merge.

Unfortunately, when motorists see a car pass them as they wait in traffic, it’s perceived as cheating, Graham said.

“What we’re seeing out there is that people in the left lane, the long lane, will actually move over and block people from traveling in the right lane to get down to the merge point,” Graham said, adding that there are YouTube videos of vehicles straddling the middle of the road to prevent drivers from passing to the designated merge point.

The ideal scenario is not to see “one big long line in the left lane” Graham said.

If done correctly, one would see how cars intertwine like a connected zipper.

Tom Herrmann, an ADOT spokesman, said it takes the combination of traffic volume and anticipated slowdown along a roadway for the merge to work. “With old-fashioned merges, most drivers move over to the appropriate lane as soon as they see traffic signs.”

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But it should be totally different when the zipper merge is implemented.

“A line of vehicles that could stretch for a mile or more in one lane can have a shorter backup and move more efficiently in two, as long as drivers cooperate at the merge point,” Herrmann said of the merge, which has been used by ADOT a few times in projects and in seven states, including Colorado and Minnesota.

So, maybe the next time you use a zipper you’ll think twice about merging over too soon — even if you upset other drivers.

“We’re trying it, we want people to use it and we certainly think that if they utilize it and merge at the merge point, then there’ll be less congestion on Kolb Road,” Graham said.

DOWN THE ROAD

• Wilmot Road at Interstate 10 is to close overnight on Nov. 1 and Nov. 6 as crews remove the temporary bridge between eastbound and westbound I-10.

Work is scheduled for 8 p.m. to 5 a.m each night.

Motorists should use Craycroft or Kolb roads. Ramps and frontage roads will remain open.

• A Southwest Gas contractor will start pipeline improvement work on La Cholla Boulevard from West Overton Road to West Tangerine Road in Oro Valley.

Crews will be working to install new gas mains until August 2019. Work will take place Monday through Saturday from 6:30 a.m. to 5:30 p.m.

There’s no anticipated interruption for Southwest Gas customers, but residents may experience road restrictions. Call the project hotline at 1-844-258-7481 for more information.

• ADOT plans to close the off-ramp from southbound Interstate 19 to Continental Road in Green Valley on Oct. 30 and 31.

Crews will work on guardrail installation each day from 7 a.m. to 4 p.m.

Drivers should use alternate exits to Green Valley. The southbound on-ramp and northbound ramps remain open.