I-70 Westbound Peak Period Shoulder Lane

The project team studied a proposal to build a peak period shoulder lane (PPSL) on a 12-mile stretch of westbound I-70 in the mountains (between the Veterans Memorial Tunnels and Empire Junction), similar to the I-70 Mountain Express Lane in the eastbound direction. The team completed the study—a National Environmental Policy Act process—in November 2018. Construction is planned to begin in late spring or early summer 2019.

Project Overview

The project adds a 12-mile tolled westbound PPSL between the Veterans Memorial Tunnels (milepost [MP] 243) and the U.S. Highway 40 and I-70 interchange (exit 232). Improvements include:

The general purpose lanes and shoulder of westbound I-70 are resurfaced and widened in select locations on the existing alignment to accommodate a lane on the shoulder for use during peak travel periods. Drainage enhancements include a storm system for minor and major storm events and water quality facilities. At State Highway 103, I-70 is slightly realigned to enhance safety and improve drainage.

The two general-purpose lanes remain open and free to all travelers at all times. During non-peak travel periods, the PPSL is closed to traffic and functions as an extra-wide shoulder. Similar to the eastbound I-70 Mountain Express Lane, the westbound PPSL uses transponders and license plate tolling. Pricing is 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 coincide with peak travel periods on weekends and holidays.

A total of seven new safety pull-outs are built – five along westbound I-70 and two along eastbound I-70. One existing safety pull-out on eastbound I-70 is improved. The intention of these is to provide a space for vehicles to use if they experience a break down and for law enforcement to use.

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

Rockfall mitigation measures are added at five locations to reduce the chance of rocks or other debris from falling on travel 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 informs drivers when the PPSL is available for use to reduce congestion. This innovative design improves mobility..

Fiber optic cables are 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 include restriping of I-70 to reduce merge conflicts between truck traffic and the general-purpose lane traffic.

Project Facts

  • Cost: $60-$70 million
  • Location: Westbound I-70 between the Veterans Memorial Tunnels (MP 242) and Empire Junction (mile point 230).
  • Team: The project followed the I-70 Mountain Corridor CSS process. This process included establishing a project leadership team, a technical team, and several issue task forces that discussed impacts to historic properties, wildlife and water resources.

    The CSS process included 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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