I-70 Westbound Peak Period Shoulder Lane

A project team is studying a proposal to build an Express Lane on a 12-mile stretch of westbound I-70 in the mountains (between Empire Junction and the Veterans Memorial Tunnels), similar to the I-70 Mountain Express Lane. The team plans to complete the study—a National Environmental Policy Act process—in fall 2018. Construction is planned to begin in late spring or summer 2019, assuming funding is identified.

Proposed Improvements

The project proposes adding a 12-mile tolled westbound peak-period shoulder lane between the Veterans Memorial Tunnels (mile point—MP—243) and the US Highway 40 and I-70 interchange (exit 232). Proposed improvements include:

The team proposes I-70 be resurfaced and widened by small amounts in select areas to convert the shoulder into a tolled travel lane during peak periods (Peak-Period Shoulder Lane, aka PPSL). This would create:

  1. Three travel lanes during peak periods.
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  3. The addition of new emergency pull-outs for emergencies and enforcement.

The two general-purpose lanes would remain open and free to all travelers at all times. During non-peak periods, the PPSL would be closed to traffic and function as an extra-wide shoulder.

Similar to the eastbound I-70 Mountain Express Lane, the westbound PPSL would use transponders and license plate tolling. Pricing would be adjusted to achieve the desired lane use and provide drivers with a reliable travel time option through the corridor during peak periods. The operational days and times would coincide with peak travel periods on weekends and holidays.

Ramp improvements at the US 40 interchange would reduce vehicular collisions with wildlife. Every year, an average of eight wildlife-vehicle collisions are reported to law enforcement in this area. Improvements include introducing a stop sign on the westbound I-70 on-ramp from US 40 and adding warning signs.

Ramp improvements would address sight-distance problems. The pedestrian sidewalk would be improved by adding lighting and a decorative paving buffer adjacent to the existing sidewalk on the CO 103 bridge over I-70. This sidewalk would connect to a new sidewalk buffered from 13th Avenue between the interchange ramp and Idaho Street in Idaho Springs.

To accommodate the Westbound PPSL, a rock cut would be required on the north side of I-70 at MP 239, at the westbound I-70 on-ramp at the west end of Idaho Springs. Rockfall mitigation measures would be added at four locations to prevent rocks or other debris from falling on lanes or shoulders, and reduce the potential for crashes and travel disruptions.

Westbound I-70 is frequently affected by rockfalls; in 2014, I-70 was closed in both directions just west of Idaho Springs for three days.

Dynamic signage would inform drivers when the peak-period shoulder lane is available for use to reduce congestion. This innovative design improves mobility.

Fiber optic cables would be specifically designed and located to accommodate future emerging technologies for autonomous and connected vehicles, improving driver information and emergency response capabilities.

Merge-area improvements to the Dumont interchange acceleration lane would include restriping of I-70 to reduce merge conflicts between truck traffic and the general purpose lane.

Project Facts

  • Cost: $70-$80 million
  • Location: On westbound I-70 between Empire Junction (mile point 230) and the Veterans Memorial Tunnels (MP 242)
  • Team: The project is following the I-70 Mountain Corridor CSS process. This process includes establishing a project leadership team, a technical team, and at least three issue task forces to discuss impacts to historic properties, wildlife and water resources.

    The CSS process includes establishing a context statement and core values of safety; mobility and accessibility; implementability; community; recreation; environment; engineering criteria and aesthetic guidance; sustainability; historic context; and decision-making.

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The I-70 Mountain corridor is a magnificent, scenic place in close proximity to the Denver Metro area. Human elements are woven through breathtaking natural features. The integration of these diverse elements has occurred over the course of time. The corridor is a recreational destination for the world, a route for interstate and local commerce and a unique place to live.

I-70 is also federally designated as a high-priority corridor, a significant part of the defense network, a major east/west continental corridor and a major economic corridor for Colorado. For many local communities along the corridor, I-70 is the lifeline, primary access and only connection to other communities.

Current I-70 roadway geometry is constrained with narrow shoulders and tight curves that impact safety, mobility, accessibility, and capacity for travelers and residents. In a manner that respects the unique environmental, historic, community and recreational resources in Clear Creek County, westbound improvements are needed to lessen delays caused by peak period volumes.


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