Construction season in the Colorado High Country is nearing an end as colder, snowier weather moves in and forces projects to wrap up.

On Interstate 70 and other mountain highways, the Colorado Department of Transportation 

made progress on major projects over the last several months, but more work will be required next summer.

“Due to Colorado’s limited construction season, major projects are rarely completed in a single year,” said Austyn Dineen, CDOT’s communication manager for the I-70 mountain corridor. “CDOT is also mindful of the impacts projects have on the traveling public and works to minimize disruptions whenever possible.”

While CDOT completed work on U.S. Highway 40 in and around the Winter Park area, construction continued this summer on the I-70 West Vail Pass Auxiliary Lane and the Glenwood Canyon Bridge Joint Improvements projects, both of which remain on track to be finished in 2026.

Work also continued on the I-70 Floyd Hill project ahead of the winter season. The costs of that project, initially estimated at $700 million, have since risen to an estimated $905 million, Dineen said. The cost increase is due to the rising costs of construction and materials.

“As the only east-west interstate crossing Colorado, CDOT recognizes that many people rely on the I-70 mountain corridor,” Dineen said. “Major projects — such as the Floyd Hill improvements and the I-70 West Vail Pass Auxiliary Lane — are focused on improving travel reliability and ensuring the safety of everyone who travels I-70 and beyond.”

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<figcaption class="wp-element-caption">Backhoes work on a hillside above Interstate 70 near Floyd Hill after rock scaling operations were performed there during the summer of 2025. The Colorado Department of Transportation is wrapping up its construction projects for the year, although major projects like Floyd Hill will resume next season.</figcaption><figcaption>Colorado Department of Transportation/Courtesy photo</figcaption>

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Here’s a deeper look at the major mountain projects that CDOT made progress on this summer, and what work remains to be done:

Completed this season

CDOT completed repaving work this summer on I-70 at the Eisenhower-Johnson Memorial Tunnels. The work removed the existing pavement on the right lanes through both tunnels, replacing it with new asphalt. The work also included restriping the lanes.

On eastbound I-70 from Chief Hosa to Morrison, CDOT is planning to wrap up a resurfacing project by the end of November. The project also included replacing guardrail, repairing two bridge decks at the Morrison exit, installing drainage improvements and adding variable speed limit signs and message boards.

On U.S. Highway 40, a resurfacing project improved about four miles of road from Vasquez Road to Winter Park Drive — adding new pavement, replacing guardrail and replacing wheelchair accessible ramps in several locations.

In Grand County, another project on a 2-mile stretch of U.S. 40  from Granby to Tabernash is expected to wrap up by late October or early November. This project includes resurfacing work, shoulder widening, barrier and guardrail installation, new signage, striping and other improvements, according to CDOT.

In the town of Empire, CDOT also has a project to replace two traffic signals, upgraded crosswalks and curb ramps. While some work remains, CDOT said it plans to complete all major construction items before Thanksgiving, except for traffic signals that will be installed in December.

I-70 West Vail Pass Auxiliary Lane Project

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<figcaption class="wp-element-caption">Construction advances on a new bridge along Interstate 70 near East Vail and Vail Pass. The new bridge is part of the West Vail Pass Auxiliary Lane Project that is expected to be completed in 2026. </figcaption><figcaption>(Colorado Department of Transportation/Courtesy photo)</figcaption>

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The I-70 West Vail Pass Auxiliary Lane Project, which began in 2021, is designed to improve safety and operations in both directions along West Vail Pass, where there are steep grades and tight curves.

This construction season, CDOT completed work on the eastbound auxiliary lane from about Mile Post 187 to 190, construction of eastbound and westbound bridges at Mile Post 185, 6 miles of resurfacing from Mile Posts 179 to 185, relocation of the Vail Pass recpath and installation of a highway closure system gate on westbound I-70 at Mile Post 190. Construction of a U.S. Forest Service parking lot at Big Horn Road was also completed.

Next summer, CDOT plans to complete the construction of six wildlife underpasses, including two for large animals and four for small- to medium-sized animals, an avalanche and rockfall mitigation system for an area known as the Narrows near Mile Post 186 and work on westbound I-70.

Glenwood Canyon Bridge Joint Improvements

During the summer season, CDOT completed work on six bridge joints on the east end of Glenwood Canyon near Exit 129 to Blair Ranch. The project plans to wrap up work before the Thanksgiving holiday.

During the 2026 season, there are 18 bridge joints that will be completed near Exit 123 to the Shoshone Power Plant and Exit 125 to Hanging Lake, according to CDOT.

Floyd Hill

The Floyd Hill Project includes various improvements — including a third westbound I-70 travel lane that aims to fix the current two-lane bottleneck to improve travel time reliability — along an 8-mile stretch of the I-70 corridor from west of Evergreen to eastern Idaho Springs. Construction on the project began in 2023 and is expected to continue through 2029.

Before the end of the winter, Dineen said CDOT plans to finish paving a section of I-70 that has been realigned after 128 rock blasts this summer removed nearly half a million tons of rock. She said rock blasting will resume next year.

Work is ongoing for the foundation and piers for the future segmental bridge that will take westbound I-70 off of its current alignment at the bottom of Floyd Hill. 

I-70 Straight Creek Culvert Repairs

CDOT began work this year on a two-year project to replace roughly a mile of culverts along I-70 in both directions between Silverthorne and the Eisenhower-Johnson Memorial Tunnels. The work is approximately 25% complete, with the remaining work expected to be completed next summer.