Wanting to untangle traffic, Dillon looks at roundabouts for US Highway 6
U.S. Highway 6 through Dillon could receive a well-rounded change in the coming years. One proposed roundabout could replace the current four-way intersection where the highway intersects Lake Dillon Drive, and a second would sit about a quarter-mile to the west, where the highway intersects with Evergreen Road complimenting plans to construct more than 150 workforce housing units on U.S. Forest Service land just northwest of town, according to the proposed plan.
Transportation Planning Department Manager Paul Silberman, of engineering consultant group Mead & Hunt, guided town councilors through proposed designs for the two roundabouts, bringing councilors up to speed on the situation since talks in 2021. The roundabouts would attempt to address traffic buildup during even the busiest of ski days.
“We’re looking at about 1,000 vehicles per hour in one direction and about 2,000 total on Highway 6 in the busiest hour,” Silberman said.
Mead & Hunt graded wait times at the current Lake Dillon Drive and Highway 6 intersection on a scale of A, best, through F, worst. It simulated wait times based on Dillon’s hypothetical traffic and population in the year 2040. Evergreen exiting on to Highway 6 earned an E grade, the second lowest possible score. Lake Dillon Drive entering Highway 6 earned a D grade. Both directions of Highway 6 earned a C grade. Silberman clarified the grading by saying the traffic light was coded to favor traffic on Highway 6, “as you would expect,” he said.
Under the current configuration, by 2040 the wait time at peak summer hours to exit County Road 51 near the expected housing development could reach 400 seconds, or 6 minutes and 40 seconds, according to Mead & Hunt’s simulations.
“Basically, you cannot get out. So you’d have to put a police officer there or some other kind of like flashing light,” Silberman said. “So although the main intersection in itself can handle the housing units — can handle regional growth over the next 20 years — the issue on CR 51 is really compounding.”
Using GPS data from phones, Mead & Hunt found how long it would take a driver to travel from Interstate 70 to Evergreen Road at the top of Highway 6 and vice versa. It took drivers an average of 1.5 minutes longer to travel westbound in the summer in 2021 than it did in 2017, according to Mead & Hunt. In the winter, times have been more consistent, Silberman said, with times trending around the three-minute mark.
“So the summer volumes and travel times seem to be ticking up, and the winter at worst is inclusive and at best is showing a little bit of improvement,” he said.
The, first, four-way roundabout would connect the highway to Lake Dillon Drive and Evergreen Road. The, second, three-way roundabout would connect County Road 51 to the highway.
The highway is part of CDOT’s hazmat route for trucks coming over Loveland Pass, and Silberman said the roundabouts would be constructed with semitrucks in mind. A concrete apron similar to the roundabouts in Frisco would allow large trucks to drag their back tires over the center median, and Dillon’s roundabouts would be about 170 feet in diameter, unlike Frisco’s. Dillon Town Engineer Dan Burroughs said the roundabout in Frisco was only about 120 feet.
In addition to the change to the roadway, new pedestrian paths would be built.
Silberman said the roundabouts would reduce the distance one needs to travel to cross the highway. Rather than crossing the highway’s current seven lanes of traffic, a roundabout could reduce the distance to 48 feet Silberman said that’s about 36 feet less than the current distance.
“We want all this to be accessible on foot,” he said. “The lynchpin of that is that you have to cross the street.”
County Road 51 could become a pedestrian-and-cyclist-only road if the plan is implemented. Silberman said the pavement would remain, but collapsable bollards would stop large vehicles and the road lines would be repainted with lanes for cyclists and pedestrians. Doing so, the town could reopen the road to vehicle traffic during emergencies and after a concert or other traffic-heavy events, he said.
Other pedestrian paths could be built along the highway as part of the project. Mead & Hunt’s proposed designs showed paths connecting the Dillon Ridge Shopping Center, the Dillon Valley neighborhoods, town center, the lakefront, the tenderfoot trailhead and proposed workforce housing. All paths would connect at the Lake Dillon Drive roundabout.
Mayor Carolyn Skowyra asked if an underpass for pedestrians and cyclists had been considered, rather than having folks navigate crosswalks. Unfortunately, Silberman said that would more than double the cost of the project and CDOT would not contribute to such an endeavor. Building a tunnel below the road would likely require crews to lower fiber optic cables and other things located below the highway.
“Don’t abandon the dream,” Dillon town engineer Dan Burroughs said. A pedestrian underpass could join the list of 20-year capital projects, he added.
Mayor Pro Tempore Brad Bailey asked if Mead & Hunt’s models considered Dillon’s growth in population. Silberman said yes.
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