The I-70 West Vail Pass Auxiliary Lanes project will shut down for the winter this week, marking a halfway point in the project’s six-year timeline.

The interstate will have full-width inside and outside shoulders and full-width lanes during the shutdown “so as not to constrict the roadway and maintain the road just as safe as it was before,” said John Kronholm with the Colorado Department of Transportation, the project’s resident engineer.

Kronholm said that duration-wise, the six-year project is halfway completed, but the bulk of the project work will take place next summer as construction will begin on the auxiliary lane for which the project is named.

In the summer and fall of 2023, crews created a wider radius on one of the dangerous curves, something CDOT expects will reduce crashes on the dangerous stretch of roadway. Vail Pass has the highest crash rate on I-70 in Colorado.

“The primary purpose and need for (the Vail Pass project) is safety improvements … there’s certain crash modification factors you can apply, and the larger the curve you have — the larger the radius — the safer the curve gets,” Kronholm said. “The way it was originally designed, they truly made an effort to match the topography as much as possible, so the roadway laid light on the land. And as a result of that, there are some curves that the speed rating would be less than the posted 65 miles per hour.”

A large retaining wall alongside the new curve was constructed, and a bridge on the curve was replaced. Some of the bridgework has caused the total project cost estimate to increase above the $170 million estimate from 2022.

“We’ve added some additional scope to the project, and the value now is around $300 million for this whole phase,” Kronholm said.

The project got underway after CDOT was awarded a $60.7 million Infrastructure for Rebuilding America grant in 2020. Work began in 2021 with the reconfiguring of the emergency exit at mile point 182, offering a straighter alignment than the previous option. Gov. Jared Polis, at that time, visited the job site and commented on how important the project will be for safety and economic improvements.

“We know how important it is to keep this highway open and moving,” Polis said. “Whenever Vail Pass is closed for an incident, it costs a lot of money. These safety improvements will reduce the cost of closures, the time in duration of closures going forward, improving the flow of traffic and making Vail Pass safer for motor carriers and for vehicle traffic.”

In 2021, CDOT completed an environmental assessment of the entire long-term plan for Vail Pass, which includes 10 miles of extra lanes in both directions.

“Right now the estimate is like $1.2 billion to do the whole thing,” Kronholm said.

The phase of the project which is currently underway only envisions 5 miles of extra lane in the eastbound direction; construction of that lane is expected to begin during the spring of 2024.

“What I would expect to see next summer is a lot of work in the eastbound lane essentially starting to build the walls there, as best as possible we’re going to keep I-70 where it is, and essentially glue that third lane onto it,” Kronholm said.

In doing so, Kronholm said the contractor should be able to maintain two lanes for most of the summer, but some lane closures may be necessary.

“They’ll have to follow a lane closure strategy to hopefully reduce traffic impacts as best as possible,” he said. “They’d just narrow it up, reduce the shoulders, reduce the lane width, and then the contractor has that room, essentially on the right side of the road, to start adding on the third lane over there which, in some cases, because of the topography, will mean the construction of walls up there.”

Just who that contractor may be is yet to be determined. The 2024 work will go out to bid prior to the spring thaw, in a standard design-bid build process.

“If we get multiple bids on the project, then of course you increase your chances of it coming in at budget, at the estimate,” Kronholm said. “That’s the primary method of procurement for CDOT — low bid.”