Kiewit Infrastructure is poised to enter the final year of construction for the Colorado Department of Transportation's (CDOT) I-70 West Vail Pass Auxiliary Lanes Project designed to improve safety and operations in both directions of the highway on West Vail Pass.
The Eagle County project, anticipated to cost $325 million, began in August 2021 and is scheduled for December 2026 completion.
Colorado Department of Transportation photo
The project limits extend from the East Vail Exit at mile point 180 to the Vail Pass Rest Area at mile point 190. The work includes a wide range of improvements to address the unique nature of Vail Pass. The highway, which has two lanes in each direction, has shoulders on either side and is separated by a green median.
"The project is part of CDOT's statewide 10-year plan and focuses on significant safety improvements for the I-70 mountain corridor," CDOT Executive Director Shoshana Lew said. "The size and location of this project require more than one construction season. It is necessary to reduce crashes and improve travel times for travelers on this section of I-70, which has the highest crash rate for all of I-70 in Colorado."
CDOT spokesperson Austyn Dineen provided more details.
"This stretch of I-70 includes steep grades and tight curves and the intermingling of faster-moving passenger vehicles with slower-moving trucks that often results in inconsistent and slow travel times along the corridor," she said. "The project is aimed at improving safety and traffic flow to create more reliable travel times along the I-70 Mountain Corridor.
"The new eastbound I-70 auxiliary lane between MP 187.3 and 190 provides slower-moving traffic, such as commercial vehicles, with a dedicated climbing lane over Vail Pass," she said. "This addition creates a safer buffer between slower traffic and faster-moving passenger vehicles, helping to address speed differentials that often cause safety concerns and disrupt traffic flow along the corridor."
Crews are reconstructing two aging bridge structures at mile point 185.2 and relocating a 2-mi. section of the Vail Pass Recreation Trail to improve the recreational experience.
Colorado Department of Transportation photo
Kiewit initiated a winter shutdown in early November to avoid interfering with winter and ski season travel, as well as snow removal and maintenance operations. Work is expected to resume in early April.
During the work season, the DOT reduced lane and shoulder widths along I-70, instituted overnight single-lane closures in both directions of I-70 and created short-term stops during evening rock blasting activities.
RS&H designed the project.
"Last summer, crews completed construction of the new eastbound bridge at MP 185.2, a counterpart to the existing westbound bridge, and demolished the old eastbound bridge," Dineen said. "Designed for a 100-year lifespan, the new bridge features improved curve geometry, spans more than 560 ft. in length and includes over 22,250 sq. ft. of new driving surface. The expanded bridge width also provides wider shoulders and added space for emergency response vehicles in the event of lane blockages."
In summer 2022, nearly 2 mi. of the Vail Pass recreation path were reconstructed to accommodate the I-70 improvements.
"The rebuilt path enhances safety and user experience while creating space to widen eastbound I-70 for the new auxiliary lane," Dineen said. "New drainage systems and collection basins were installed to help prevent sediment from entering Black Gore Creek."
A highway closure system also is being installed.
"In addition, a new retaining wall was constructed beneath the bridges to support the relocated path," Dineen said. "Information technology service improvements are under way in conjunction with the utility work for a westbound highway closure system at Vail Pass I-70 MP 190 interchange and future speed limit and message signs."
The 10-mi. stretch of road passes through mountainous terrain, with forests and meadows on either side. Kiewit crews have access to the medians to store materials, set up field offices and park equipment. Operations occur between Monday and Saturday, which includes nighttime work.
The work completed so far in 2025 includes: a highway closure system gate and the eastbound I-70 auxiliary lane. The remaining work entails wildlife crossings — two for large animals and four for small- to medium-sized animals — an avalanche and rockfall mitigation system and westbound I-70 road work and resurfacing.
Colorado Department of Transportation photo
"Construction challenges include a short construction season at nearly 11,000 ft., as the snow doesn't melt until early May and starts to stick to the ground around the end of October," Dineen said. "Most nights in the summer are in the low 40s. The project is located in [United States Forest Service] environmentally sensitive property, and special attention was paid to water quality as well as nighttime restrictions to avoid interfering with threatened and endangered species."
Two aging bridge structures at mile point 185.3 were replaced.
"The existing bridges were steel girders with a concrete deck," Dineen said. "For safety, bridge demolition was completed by saw cutting and lifting away each panel with a crane. The concrete was then crushed for reuse on site as road base, and the steel girders were recycled. The new bridges are concrete tub girders placed with two cranes and then a pre-cast panel deck with a deck pour on top."
Equipment used included excavators, skid steers, loaders, off-road haul trucks, asphalt pavers, slipform concrete liners, dump trucks and compactors.
Blasting was completed in 2022 for the relocation of the recreation path. In 2025, the team performed rock scaling on I-70 westbound in an area known as "the narrows."
"A passive avalanche mitigation and rockfall fence will be installed at MP 186," Dineen said. "The fencing will help stabilize the snowpack and catch smaller, initial snowslide movements. The system will allow CDOT and the Colorado Avalanche Information Center to safely monitor and manage a known avalanche slide path and prevent extended interstate closures. Fence installation work required rock scaling and helicopter operations, requiring 20-minute traffic holds of I-70 in both directions and the Vail Pass Recreation Path."
Typical days have 60 Kiewit and subcontractor employees on site.
The amounts of materials excavated and demolished, and new materials brought in, have not been finalized.
As the project is in a remote area, Kiewit has on-site and visiting mechanics to help maintain its fleet, be it for daily wear and tear items or for routine maintenance.
The firm buys and rents equipment from dealerships with which it has long-established relationships. CEG
