A removable third lane may be the next project the Colorado Department of Transportation tackles to relieve traffic on the Interstate 70 mountain corridor, officials announced this week.
CDOT is calling it a "peak-period shoulder lane," and it would run from Empire Junction to the Idaho Springs area, where it would tie into the Twin Tunnels widening project and form a three-lane highway all the way into Denver.
Officials say they would repurpose the shoulder space to create the third eastbound lane only during heavy congestion on the corridor.
"Five percent of the time - during peak periods - we would open it up to traffic and charge a toll," said CDOT project manager Jim Bemelen. "Essentially it helps keep traffic moving."
The removable lane would be on the far left of the highway, to avoid slowdown from exiting vehicles.
The shoulder lane would connect with the new permanent lane at the Twin Tunnels, the end goal of a $100 million tunnel-widening project set to begin in April. That lane will eventually be tolled as well.
Transportation officials say the tolls aren't intended to cover construction costs, but to help keep the new lanes from becoming as congested as the old ones.
"The funds generated barely cover the added operational cost," said CDOT official Tony DeVito, who noted that tolled lanes will get a higher level of service in terms of maintenance and snow removal. "If you build it, it will just eventually congest. But (other states) are getting longer life out of the road because it's priced."
Toll prices could be adjusted up or down depending on traffic demands.
Still, local officials warned that mountain communities have less patience for tolls than Front Range residents.
"The buy-in on tolling is, I think, a really important component," Summit County Commissioner Dan Gibbs said. "It's accepted on the Front Range, but not up here."
Work on the Twin Tunnels will close all eastbound lanes of the highway through the spring and summer. Traffic will be detoured on an adjacent frontage road. The project will also cause occasional stops for westbound traffic when crews are blasting inside the tunnel.
Transportation officials said stops would be scheduled around peak travel times.
The widening project is slated to wrap up by October 2013. It is unclear how much it will cost.