Traffic flows on westbound C-470 between Yosemite and Quebec during rush hour Wednesday.
Traffic flows on westbound C-470 between Yosemite and Quebec during rush hour Wednesday. (Karl Gehring, The Denver Post)

 Toll lanes may soon be added to pay for improvements to C-470, a freeway built to relieve congestion southwest of Denver but now choked with traffic jams considered some of the worst in the metro area.

"Our biggest nightmare now is C-470," said Douglas County Commissioner Jack Hilbert, a leading proponent of the toll lane idea.

Hilbert and others in a group called the C-470 Corridor Coalition — formed in 2011 — say toll lanes are the fairest and quickest way to remake the road that swings around the southwest side of the metro area from Interstate 25 to Interstate 70.

Rush-hour traffic clogs westbound C-470 between Yosemite and Quebec Wednesday. More than 100,000 vehicles a day travel the busiest stretches of C-470.
Rush-hour traffic clogs westbound C-470 between Yosemite and Quebec Wednesday. More than 100,000 vehicles a day travel the busiest stretches of C-470. (Karl Gehring, The Denver Post)

More than 100,000 vehicles a day travel the busiest stretches of C-470, parts of which were constructed more than 20 years ago.

A Colorado Department of Transportation study estimates that by 2025, population in the C-470 corridor will swell 34 percent, to 708,000 people.

Without some form of help for the segment between Kipling Street and I-25, in particular, nearly every link in the corridor will be rated "level of service F" because of stop-and-go conditions with extreme delays, according to CDOT.

"Driving that corridor is a key to economic development in Douglas County," Hilbert said. "But at times during the day it's nothing but a bottleneck. Let's face it, during rush-hour traffic it's a zoo."

Douglas County resident Pat Perlinger witnesses C-470's woes each day.

"I drive under C-470, either in the morning or in the evening, and the bridge is loaded with cars and many times they are just standing still," Perlinger said. "Usually during the day, it's no big deal. But in rush hour, it chokes up something fierce."

The last attempt at finding funding for improvements to the 26-mile freeway collapsed six years ago because communities found the way the cost of the project — then estimated at $350 million — would be billed to them inequitable.

But the C-470 Corridor Coalition — which includes representatives from several cities and other entities along the freeway — represents a hardened resolve to come up with solutions, Hilbert said.

The coalition decided to focus first on the segment from I-25 to Kipling and estimates expanding that 12-mile stretch of the freeway will cost about $200 million.

The group then spent several months talking to residents, and in November commissioned an opinion survey to gauge the public's appetite for improvements.

The random survey of active voters in Jefferson, Douglas and Arapahoe counties showed "mixed or ambivalent" views on paying for improvements, according to Hill Research Consultants, which conducted the survey.

Those polled, Hill Research concluded, "do not place a very high priority on making improvements to C-470."

Last week, the coalition's technical committee issued its recommendation: Build one new, tolled lane in each direction. Motorists would be charged 31 cents a mile for its use, or $3.65 for the entire length of the segment

Outside auxiliary lanes would be built where warranted. The existing lanes in each direction would remain toll-free.

Another option called for tolling all lanes along the segment while another would raise sales taxes or property taxes to fund the fixes.

But a single tolled lane in each direction struck the right chord for the coalition, spokesman Roger Sherman said.

"It allows people the true choice," Sherman said. "They can stay in a non-toll lane, but if they feel they need to get somewhere quicker they can choose to pay for an express lanes to get them there faster."

Tolling all lanes of the road could have required a vote, Sherman said. "We'd also have to define the boundary of a taxing district and there are difference scenarios that come with that."

The coalition is likely to make its full recommendation for a preferred option next month.

Coalitions officials downplayed the results of the November telephone survey.

Hilbert said many of those surveyed may not use C-470 at all and are not directly impacted by the freeway.

"People who do drive C-470 every day know it's a challenge," Hilbert said. "We really can't wait too much longer to fix it."

Monte Whaley: 720-929-0907, mwhaley@denverpost.com or twitter.com/montewhaley