DENVER — Zip it, Colorado.
It is time to embrace the zipper merge.
The City of Denver has reduced northbound Speer Boulevard down two lanes approaching Wewatta Street to refresh the third of three bridges between downtown and Interstate 25.
Work on the other two bridges was completed last year.
The work is being done outside Ball Arena, which hosts Game 6 of the Colorado Avalanche's Western Conference Semifinals series on Friday and Game 7 of the Denver Nuggets' Western Conference Semifinals series on Sunday.
Zipper merging can speed up traffic approaching a lane closure and exiting parking lots after sporting events and concerts.
“The failure, believe it or not, are, kind of, courteous drivers,” MSU Denver transportation professor Steve Long said.
The courteous drivers are the ones who back up traffic.
The concept of a zipper merge is to use the lane that is closing all the way to the closure, and then alternate into the next lane over. One from the closing lane, one from the existing lane, one from the closing lane, one from the existing lane.
“We could be so much more effective. A lot like fluid mechanics, a lot like aerodynamics, if we arrange the molecules in a way that have a nice even flow,” Long said. “If we could fill up both lanes and then, at one single point, continually right lane, left lane, right, you could actually keep the whole flow moving.”
By trying to get over early, drivers leave empty space in the roadway that could be used, while backing up traffic earlier than necessary behind them.
“If we just zipper in at the right speed and at the right single point, we can avoid a lot of the turbulence,” Long said. “In reality, if all these cars would fill up that lane and we would just be able to cross at the end of that taper, clear on the other side of the intersection, one-by-one, this traffic would move a lot better.”
He said that research shows it speeds up traffic through the construction area considerably.
“Forty percent better capacity, mobility through an area if you’re dropping a lane and you’re zippering lanes in an organized fashion. A non-turbulent fashion,” Long said.
Most of the drivers that Long watched on Friday afternoon would get a failing grade in merging.
“Here’s an example, a truck that’s trying to get over early, he should just be staying in the lane. He thinks he’s doing the right thing by getting over. Now, look what’s happened here. This lane has become empty. It’s starved if you will, of traffic, and that means less traffic is getting through this single point,” Long said.
The City of Denver will reduce southbound Speer Boulevard approaching Wewatta Street down to two lanes after the Avalanche's and Nuggets' seasons are done, so drivers will see the reduced lanes in both directions.
"Zippering is what is going to make this traffic flow better. And when we're in line, side-by-side, it's better than trying to butt in or get in early,” Long said.
More reporting by Marshall Zelinger:
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