Colorado Department of Transportation officials are examining the congestion-relief project proposal that Parsons, a private company, pitched for the Interstate 70 mountain corridor, but they haven’t signed on to anything yet.

The pitch, which was submitted in 2011, is being vetted through a traffic and revenue study, along with elements of another industry proposal and CDOT ideas for the highway, but is nowhere near final approval for implementation, transportation spokeswoman Amy Ford said.

“That is definitely not part of where we are right now in our thinking,” she said. “Our focus is one — complete the Twin Tunnels (widening project); two — start the planning of our peak period shoulder lanes and then three — work on this traffic and revenue study.”

The study itself is just getting underway and could take up to 18 months to complete, during which time state crews will continue expanding I-70 to three lanes at the Twin Tunnels, east of Idaho Springs, and preparing a new plan that would utilize shoulder space to create a removable third-lane to help increase traffic flows during heavy congestion on the highway.

The Parsons proposal outlines a public-private partnership to implement $3.5 million in traffic-reduction measures on the crowded interstate with a tolling structure that would allow the project to pay for itself.

The first phase of the plan calls for new reversible express lanes to be constructed in the median area of the existing highway between C-470 and Silverthorne ­ — the segment that experiences the worst backups — and would require new bores through both the Eisenhower and Twin tunnels. The new express lanes — meant to provide an alternative to sitting in traffic for drivers on busy travel days — would be tolled to help cover the cost of the project itself as well as the launch of a rapid transit bus system which would provide service all the way to Vail. At a recent Eagle County presentation of their plan, Parsons representatives said their tolled-lane model would be expected to generate more than the total cost of the project.

The tolls will be adjusted up and down as needed to ensure the express lanes do not become congested.

“With max pricing, a trip from Denver would cost about $26,” Parsons program director Trapani said at the presentation. “How much is your time worth — do you sit in gridlock traffic or pay, knowing you can maintain 60 mph to your destination?”

A second phase of construction would extend the highway improvements from Vail to Silverthorne.

The Parsons proposal does not include plans for a high-speed rail on the corridor, but transportation officials said they have not abandoned the idea. A separate, but parallel study to the traffic and revenue analysis is being conducted to determine whether a train, known as an advanced guideway system (AGS), would be financially feasible.

“There are certainly some high costs associated with (the AGS). Right now we’re trying to figure out does that make this project something that’s not possible at this time,” Ford said. “We’re looking at all of it.”

Existing technology for a high-speed rail that can handle the unique grade and weather challenges of the I-70 mountain corridor could run upwards of $20 billion to construct, and more recent studies show the train might not draw the ridership numbers once anticipated.

The results of AGS financial feasibility study are expected to be released later this year.

Derek Franz of the Eagle Valley Enterprise contributed to the reporting of this story.