Lucky Stripes? CDOT tries adding a fast lane to notorious I-225 junction

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AURORA | You know the drill. Get on Interstate 225 southbound and relish the many and wide lanes until you almost always have to stop and inch up to the junction at Interstate 25.

Morning, noon and night — I-225 going south can back up for miles, as commuters creep toward the split to head either north or south on I-25.

The frustration of I-225 has been there for years, actually made worse by improvements to the north, moving traffic even faster to bunch up on the south end.

Years late, state highway officials may have found a solution that involves not a whole lot more than painting new lines on the roadway and changing a couple of signs. The agency started studying a solution to the problem in 2014, according to Colorado Department of Transportation spokeswoman Tamara Rollison. This month those studies have become a reality.

So far, the anecdotal evidence looks good for the pilot project by the CDOT that transformed a shoulder into a lane on a stretch of the highway.

The agency re-striped I-225 from south Yosemite Street to I-25, a little less than a mile of road. But CDOT expects that extra lane to lessen congestion quite a bit.

“CDOT conducted two independent studies that showed delays during rush hours. Studies also showed we could cut that more than half,” said Stacia Sellers, a spokeswoman for the agency.

CDOT claims the approach to the I-225 junction is one of the worst places to hit traffic in the entire Denver metro area. Surveying traffic shows just how congested the commute can get.

A CDOT analysis of traffic volumes concluded that nearly 19,000 total cars pass the Denver Tech Center Boulevard. on-ramp at morning peak travel times. At the east Orchard Avenue on-ramp that volume climbs to approximately 41,000 cars on the road.

Monitoring devices, which work by assigning an anonymous MAC ID address to cars with a Bluetooth connection and tracks their movement past specific locations, show 4,665 vehicles use the DTC Boulevard/Tamarac Parkway and  I-225 Southbound on-ramp on an average morning at peak time. 30 percent of those end up going southbound on I-25. The other 70 percent go northbound, toward Denver. While there’s a little bit of fluctuation, that statistic holds steady for the afternoon as well.

For commuters heading toward either direction on I-25 the change is slated to speed up the commute, ultimately cutting travel time in half, according to CDOT.

“Right now we’re seeing some improvements, but it takes a little bit of time for motorists to adjust to something that’s new,” Sellers said.

The change has come with a little bit of initial confusion. Cars entering I-225 from DTC Boulevard, East Quincy Avenue and Yosemite Street can’t weave across I-225 to catch I-25 southbound. A set of barriers prevents that.

“The length of merge is too short and would create safety problems and impede with mainline traffic flow on I-225 southbound,” says a CDOT info web-page about the project.

Right now, barriers keep all of that traffic heading to the I-25 north on-ramp.

Re-striping the interstate, which started at the beginning of November, comes at a much cheaper price than building an additional lane would cost. CDOT estimates turning the shoulder into a lane will cost about $1 million, a fraction of the $65 million it would likely take to build a whole new lane. CDOT said the money it would take to add an extra lane isn’t available, and the re-striping is their best reasonable option.

As for side effects of the highway project, Aurora city officials said they don’t anticipate any major impacts beyond some extra traffic on side streets. CDOT expects delays in Hampden and Bellview avenues.

Officials don’t expect any substantive impact to I-25, either.

“With better traffic flow on I-225 southbound, traffic will enter I-25 northbound more quickly, which may slightly increase congestion on I-25 northbound,” according to a CDOT presentation on the project. “I-25 southbound is not expected to be impacted.”

Sellers said CDOT will monitor the pilot project indefinitely, as data says the re-striped road will work.

“We will monitor local roadways and other entrances onto I-25 to see how they perform,” she said. “The barrier we set is temporary, which will allow us to easily remove it if needed.”