Inside Central 70's Six-Lane Shift, Weekend Closure Traffic Nightmare

A Colorado Department of Transportation graphic showing what it's calling the "Mile High Shift."
A Colorado Department of Transportation graphic showing what it's calling the "Mile High Shift."
Approximately 200,000 vehicles have been traveling through Denver's Central 70 construction zone every day...but that stops this weekend. Starting at 10 p.m. tonight, May 21, through 5 a.m. Monday, May 24, eastbound and westbound Interstate 70 will be closed between Washington Street and Interstate 270 so that Colorado Department of Transportation crews can execute what the agency has dubbed the "Mile High Shift." The process entails repositioning all six traffic lanes between Colorado and Brighton boulevards into a lowered section covered by what will eventually be a four-acre park.

The detour necessitated by this move over parts of four days is only the beginning of the expected traffic nightmares. Stacia Sellers, communication manager for the Central 70 project, acknowledges that "with the new lowered lanes, we think there'll probably be a one-to-two-week learning curve" for drivers that will almost certainly result in more delays and greater congestion over that span, particularly during high-volume periods.

"Obviously, this is going to be dramatically different," Sellers continues. "We anticipate people looking around and seeing what we've been up to."

Among the challenges involved in the Central 70 project is "building around an active Interstate 70," she notes. "We want to make sure we're not having an impact on active lanes, which is why we're doing a weekend closure — and we haven't really seen traffic slow down that much during construction. The only times we see traffic really start to slow is when there's a new traffic configuration."

That will certainly be the case this time. According to Sellers, "We're shifting into a temporary configuration. There are six lanes of traffic — three eastbound, three westbound — in the lowered section, and we're putting them in a place that will allow us to go in and start demolishing the viaduct between Colorado and Brighton. That should take us four to five months to accomplish, and once the viaduct is demolished, we'll start building out the eastbound lanes. That should take another fourteen months, and then we'll switch the eastbound lanes into their final configuration. All traffic will be in its final alignment by the end of next year."

In the meantime, the temporary lanes will be "under cover" — a term stressed by Sellers. "I'm sure people will always refer to it as a tunnel, but by engineering standards, it's not technically a tunnel," she says. "It's a cover or a lid that's a little over 900 feet long that will go over the portion of I-70 from Columbine to Clayton. But we'll be equipping it like a tunnel, with the same kind of safety equipment you see at the Eisenhower Tunnel, including a fire suppression system. If there's a car fire, this system will go off and help suppress the flames until the Denver Fire Department arrives, and there will also be extensive lighting underneath the cover top to make sure we can keep traffic flowing and not just send traffic into this dark space. There will also be fans to help circulate air underneath the cover's top."

In addition to all the other changes, there's one move that should come as good news for residents of the Cole neighborhood, who have been dealing with horrific backups during the daytime hours owing to assorted exit and entrance shutdowns: The Brighton on-ramp to westbound I-70 will reopen on May 24.

During the tricky times ahead, drivers traveling west on I-70 can get around the closure zone by heading west on I-270 to westbound Interstate 76, then take Interstate 25 south to the westbound I-70 exit. Conversely, I-70 eastbounders will exit onto I-25 north before transitioning onto eastbound I-76 before rolling east on I-270 to the eastbound I-70 exit.

Once the new lanes are open, Sellers encourages drivers to "keep traffic flowing so we're not creating congestion or having any crashes because of people slamming on their brakes to check things out." And while one more shift is slated to happen by the end of 2022, the under-cover concept will be here to stay.

"These are going to be the new lanes," Sellers says, "and we all need to get used to them, because we'll be driving on them for the rest of our lives."

Click to get more details about the Mile High Shift.