According to Stacey Stegman, the Colorado Department of Transportation’s Director of the Office of Public Relations, federal law does not allow us to toll the existing lanes of an Interstate. There are certain pilot projects and exceptions for tunnels or to pay for reconstruction but right now CDOT has no plans to toll existing lanes. We are currently considering tolling for new lanes anytime we consider a project to add capacity (such as for new lanes or new highways). On the project we’re developing right now to add an eastbound lane through the I-70 Twin Tunnels, in Idaho Springs, we are considering tolling that lane only during peak times while the other two lanes that exist would remain toll free. I should note that this is really more to better manage congestion rather than to raise revenue. This will provide a sustainable alternative to the congested lanes for those that wish to pay to use it. They won’t have to as they will still have the free lane but if they need to catch a flight for example, they have the option to pay and have a quicker trip.
