CDOT Announces Proposal for Westbound I-70 Mountain Corridor Improvements

May 15, 2018 -

As more people move to and visit Colorado, the more difficult it becomes to travel on I-70 through the mountains. CDOT has been working with local elected officials and stakeholders to develop concepts and designs to help alleviate congestion, improve safety and maintain the unique environment of the mountains, and is moving forward with a proposed action.

As part of the proposed action, westbound I-70 will be widened from two lanes to three at Floyd Hill to accommodate more westbound travelers. I-70 will be reconfigured with simplified curves, bridges and walls to improve line of sight, and improve driver safety.

The new westbound I-70 alignment would be placed in a tunnel at the bottom of Floyd Hill to reduce weather impacts and improve driver safety. During construction, the westbound alignment can be built adjacent to existing traffic lanes—limiting impacts to the traveling public.

The project also proposes to complete a key link of shared-use trail from the Clear Creek Greenway toward the Peaks to Plains Trail in Jefferson County, which was a part of Gov. John Hickenlooper's Colorado Trails Initiative. The project will complete the trail from the Veterans Memorial Tunnels to the US 6 and I-70 interchange, building on the goal to connect Metro Denver over the Continental Divide.


The ballot estimate for improvements to I-70 from the top of Floyd Hill to the Veterans Memorial Tunnels is up to $550 million. At this time, CDOT does not have enough funding to start construction on this project once this study is complete.

As an interim solution to congestion issues along the I-70 Mountain Corridor, CDOT's project team is looking at constructing a Westbound I-70 Peak Period Shoulder Lane, or a Mountain Express Lane, similar to the eastbound I-70 Mountain Express Lane. If funding is identified for this $80 million project, construction could start in late spring or summer 2019.


CDOT has made a lot of progress since it signed the 2011 Record of Decision (ROD), which included a decision about capacity, mode and location for future transportation improvements. The I-70 Mountain Corridor ROD included the following improvements in particular for the Floyd Hill study area: six lane capacity and shared-use trail, and frontage roads from Idaho Springs to US 6.

Since then, CDOT conducted a Concept Development Process, which developed a shared vision for the corridor among stakeholders. The process focused on westbound improvements from the top of Floyd Hill to the interchange of I-70 with US 40. Through the National Environmental Policy Act (NEPA) process, the project team has been studying alternatives provided by the I-70 Concept Development Process.

Through this process, CDOT, the Federal Highway Administration (FHWA), and various local elected officials and stakeholders have moved forward with the major components of a proposed action (or concept) that will reconfigure the I-70/US 6 interchange, and will make significant safety and mobility improvements along the I-70 Mountain corridor.