Sprawling maps and sticky notes covered the Silverthorne Pavilion Nov. 19 as the Colorado Department of Transportation sought the community’s feedback on what will be a multimillion dollar effort to improve one of Summit County’s most highly trafficked areas. 

CDOT unveiled preliminary plans to boost safety and operations along U.S. Route 6 and Colorado Highway 9 in Dillon and Silverthorne following an 18-month mobility study. The study also considered Wildernest Road and Stephens Way, since both create major connections within the corridor.

Based on a statewide traffic growth model and potential developments in both towns, CDOT is anticipating traffic through the corridor will increase 45% by 2045, and officials are planning with this in mind. 

“The goal of this study the last two years has been to develop a roadmap for how we can move traffic more efficiently through the (U.S. Route 6) and (Colorado Highway 9) corridor based on traffic today and in 20 years,” CDOT project manager Karen Berdoulay said.

CDOT worked with transportation engineering firm Stolfus and Associates on the study and the subsequently recommended projects and improvements that are being considered. Initial cost estimates for around 20 potential projects state that it will cost upwards of $70 million, according to the study’s executive summary.

Berdoulay said there’s no set timeline currently for plan implementation, describing what was presented to the public Nov. 19 to be at a “10% concept level.”

With data in hand, partners will be working on a series of potential projects ranging in size and price largely targeted at enhancing traffic signal timing and access management, or systemic control of a location’s traffic operations. Some projects focus on a handful of alterations to a stretch of roadway while others are larger standalone projects. 

A project dubbed “Option 4” in the study’s executive summary has the heftiest estimated price tag, which ranges from $13.3 to $15.4 million. According to the executive summary, Option 4 realigns Stephens Way to the east and Little Beaver Trail to the west to create a single signaled, four-legged intersection. This area could also get a trail connection between Stephens Way and Little Beaver Trail, which is anticipated to cost $6.8 to $7.9 million. The executive summary details these changes should reduce conflict points, or areas where vehicles have the potential to collide. 

Other notable potential projects include a roundabout from Wildernest Road to Stephens Way and one at the intersection of Dillon Ridge Road and U.S. Route 6, alongside a pedestrian bridge on Lake Dillon Drive going over U.S. Route 6.

Berdoulay said traffic signal timing is among the top priorities and one CDOT has been working on since 2022. Traffic signal timing along the corridor improved by 17%, according to CDOT, thanks to updated technology installed on numerous signals in the last couple years.

She said a key focus of the access management plan is intersections, adding they are hoping to make changes such as modifying turn lanes to optimize traffic flow.

For instance, extending the left turn lane to get on to westbound Interstate 70 in Silverthorne is on the docket as a potential improvement. In Dillon, CDOT is looking at extending both the westbound left turn lane and the eastbound right turn lane on Dillon Dam Road.

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Another pillar of the access management plan is what CDOT describes as a “mode shift.” Berdoulay said a mode shift largely entails trying to optimize transit long term and identifying some bike and pedestrian improvements that can be made. 

“This is so that people can really start feeling comfortable getting out of their car to complete the travel they need,” she said.

While most projects are a ways down the pipeline, some are slated to happen in the next year. Grant Anderson, resident engineer for CDOT, said a new light at Ruby Ranch Road could be installed as soon as April.

Berdoulay said projects will be knocked off the list as funding for them is identified.

She said project partners are continuing to explore funding sources for the potential projects, and CDOT funding and town development dollars are options to tap into. Additionally there are federal funding opportunities such as the Rebuilding American Infrastructure with Sustainability and Equity (RAISE) grant and the Highway Safety Improvement Program grant.

Berdoulay said CDOT looked to bake community input into its vision for corridor improvements from the start.

“If you weren’t familiar with the area, the first thing you might think is ‘let’s go ahead and make (the road) wider’ … If you’re familiar with this community, you would know that’s not in line with their community values,” she said. “They don’t want to just out-build the problem.”

She said they are aiming to keep the same general footprint as they figure out how to get traffic through more efficiently.