Interstate 70 Mountain Corridor Eastbound Express Lane

Interstate 70 Mountain Corridor traffic

Interstate 70 Mountain Corridor Eastbound Express Lane

An Innovative Solution to Get Traffic Moving

Residents near Idaho Springs, Colorado, lived for years with weekend congestion on Interstate 70 that not only frustrated drivers but limited the response times of emergency vehicles and increased air pollution in the area. HDR partnered with the Colorado Department of Transportation to convert a highway shoulder into an express lane that operates under specified guidelines. This first-of-its-kind solution to the gridlock gets traffic moving more smoothly, all without requiring the taking of more right-of-way in an environmentally sensitive area.

The Interstate 70 Mountain Corridor is Colorado’s only east-west interstate and serves as the primary access route for area residents and tourists traveling between Denver and the state’s scenic Rocky Mountains. The Interstate 70 segment running from Empire Junction to the Veterans Memorial Tunnels east of Idaho Springs is one of the narrowest sections of the corridor, with the roadway located on the canyon floor adjacent to Clear Creek. This segment had experienced heavy eastbound traffic flows, causing severe congestion during peak periods, especially Sunday afternoons. On some weekends, delays could be as long as two and a half hours to travel 8 miles. As a result, access was hindered to and from recreation areas (vital to mountain town economies) and also from western-slope mountain towns to medical services, education and employment in the Denver area, about 30 miles east. 

The $70-million Interstate 70 Mountain Corridor Eastbound Express Lane project significantly reduced the impact of this heavy traffic on businesses, residences and the overall environment. We provided planning, environmental analysis, design, context-sensitive solutions and construction support on the project. 

An Intelligent Transportation System Fix

Our team designed a 13-mile eastbound lane within existing Colorado Department of Transportation right-of-way, allowing traffic to use the shoulder during peak periods. This shoulder lane is open only to drivers willing to pay a toll and it uses intelligent transportation system infrastructure, including active traffic management and dynamic pricing to manage reliability. The toll price falls to encourage drivers to use the lane and rises as the lane nears capacity. 

This award-winning project is the first and only project in the United States to use a highway shoulder as a part-time lane based on recreational traffic instead of a regular commuter base. As talks began on relieving the congestion, serious public concerns were raised about any plan’s potential impact on neighboring communities and the unique, fragile natural resources in the mountainous environment. Our team worked with CDOT and the Federal Highway Administration to develop this context-sensitive solution, which operates the shoulder lane on an interim basis and for a maximum number of hours and days annually. 


This process and federal agreement allowed for local agency acceptance and avoided the need to acquire new right-of-way. It also avoided adverse effects to historic properties, minimized wetland impacts and minimized impacts to Clear Creek. 

The project scope also included the design and reconstruction of two major Idaho Springs interchanges, as well as two bridges, a roundabout, strategic retaining walls to limit impacts to fishing and rafting along Clear Creek, and improvements to bicycle/pedestrian facilities and the historic Water Wheel Park — an iconic amenity in Idaho Springs. We helped improve wildlife connectivity by modifying existing median barriers so that wildlife can cross them. Safety and emergency response, maintenance and snow removal policies, and re-vegetation and erosion control measures were also addressed.

Faster Travel, Improved Economy

Opened in mid-December 2015, the eastbound express lane has made a pronounced difference. The new lane captured 82,600 vehicles, or 8 percent of traffic, in its first summer season, and contributed to a 40 percent decrease in travel time in the general purpose lanes. Traffic on adjacent frontage roads also was reduced. The corridor incident rate went down by 15 percent. 

The finished project has helped to improve the region substantially. Economic activity is on the uptick in Idaho Springs. Residents, tourists and emergency vehicles enjoy more reliable travel time. And less traffic congestion has led to reduced air pollution — always welcomed by Coloradoans — known for their efforts to preserve their state’s signature fresh mountain air.

Interstate 70 Mountain Corridor traffic


Honor Award (2019)
Engineering Excellence Awards
American Council of Engineering Companies
Excellence Award (2019)
Engineering Excellence Awards
American Council of Engineering Companies of Colorado
Environmental Excellence Award for Context Sensitive Solutions (2017)
Environmental Excellence Awards
Federal Highway Administration
America’s Transportation Award (2016)
American Association of State Highway and Transportation Officials, Western Association of State and Highway Transportation OfficialsRegion