Traffic congestion along the I-70 mountain corridor is a long-standing, serious transportation problem facing Colorado. This problem is not going away, since Colorado’s population is projected to increase by 50% by 2040. As the state’s only continuous east-west interstate and a virtual “main street” for local residents, severe congestion in the corridor infuriates travelers, harms local communities and small businesses, and creates challenges for intrastate and interstate commerce. Scenic mountain terrain, wildlife management and historic cultural sites create additional constraints along the corridor. Furthermore, Colorado’s outdoor recreation and tourism industry is a significant economic driver, and mountain resorts account for 30% of Colorado’s tourism revenue.

After years and years of studying and consensus building, the I-70 corridor has a blue print for future I-70 improvements. This is a federally recorded document called the I-70 Record of Decision and it will guide improvements and projects along the I-70 mountain corridor through the year 2050 and is a result of almost a decade of studies and stakeholder input. The I-70 Record of Decision represents a “preferred alternative” and consensus recommendation from a group of 27 diverse local governments, agencies, environmental groups, private-sector interests and others.



Learn more about the I-70 Plan.

Download the I-70 Plan Fact Sheet.

I-70 Record of Decision

The I-70 Record of Decision document in its entirety can be found here.

The I-70 Record of Decision (ROD) calls for a multimodal solution and a phased approach to highway improvements. Certain areas of I-70 are well known congestion pinch points. Improvements to relieve congestion at those pinch points will be made first, and the impact of those improvements evaluated before moving on to the next phase of solutions. Another notable provision in the ROD is a commitment by CDOT to apply the principle of Context Sensitive Solutions (CSS) on all projects in the I-70 Mountain Corridor. CSS is a collaborative, interdisciplinary, holistic approach that involves all stakeholders, including community members, elected officials, interest groups, and affected local, state, and federal agencies in the development of transportation projects.


Since the ROD was issued in June of 2011, some highway improvements have been made.

  • Expansion of the Veterans Memorial Tunnels (formerly called the Twin Tunnels) east of Idaho Springs. Both tunnels were widened to three lanes. A third lane of travel was added eastbound from east of Idaho Springs to the tunnel.
  • CDOT completed an Advanced Guideway System (AGS) Study. AGS is a generic term for a high speed transit system. The AGS Study found that AGS through the I-70 mountain corridor is technically feasible but is not financially feasible at this time.
  • CDOT completed the I-70 Mountain Express Lane. This project utilizes an improved shoulder as a tolled travel lane during peak travel times only, from Empire Junction to the Veterans Memorial Tunnel in the eastbound direction. More details are at CDOT’s project website.
  • Non-infrastructure improvements The I-70 Coalition, in partnership with CDOT, continues to identify and implement multiple Transportation Demand Management (TDM) strategies to positively impact congestion in the near term with a goal to decrease traffic volume during peak travel times. This is accomplished through extensive traveler education around traveling at off peak times, encouraging Sunday overnight stays, as well as reducing the number of vehicles on the corridor through ridesharing and transit options. More details can be found at the Short Term Solutions section of this website.

Future Projects

Future improvements through the mountain corridor will include:

  • A westbound I-70 Mountain Express Lane from the Veterans Memorial Tunnel to Empire Junction will, like the eastbound Mountain Express Lane, utilize an improved shoulder as a tolled travel lane during peak travel times only. This project will be complete by Summer 2021.
  • The Floyd Hill Project from the top of Floyd Hill westbound to the Veterans Memorial Tunnel (formerly called the Twin Tunnels) will add a third lane, straighten curves, replace a deficient bridge and improve multiple interchanges. Early phases of the project have dedicated funding.
  • West Vail Pass Auxiliary Lane Project will result in a third lane of travel between the east Vail exit and the top of Vail pass, both in the eastbound and westbound direction, create wildlife crossings and fences, relocate a section of the rec path, improve truck parking and ramps, and improve water quality.  Phase I has been funded.
  • Multiple interchanges from Idaho Springs to Eagle are slated for improvement.

The above projects will add some additional capacity to this corridor, but will not fix the congestion issues we currently face. According to the I-70 Record of Decision, BOTH highway widening and a transit system will be required to meet the needs of the I-70 mountain corridor into the year 2050.

The Challenge

Projects that add significant capacity to the I-70 mountain corridor will require many billions of dollars. Here are some realities:

  • The federal government hasn’t passed a comprehensive Transportation Authorization Bill since 1993. 
  • Colorado’s gas tax has not increased in over 20 years.
  • Currently, CDOT’s budget is barely able to cover Operations & Maintenance, much less building new capacity. 
  • CDOT estimates it has $9B worth of backlogged projects/maintenance needs.
  • When polled, Colorado voters rate the need to improve our transportation systems as high. Lawmakers from both parties realize the critical need for investment in Colorado’s transportation infrastructure, but there is no consensus on the mechanisms to secure those dollars.

The state of Colorado will need to determine a way to develop new transportation funding sources in order for the long term I-70 solution to be realized.

Stay Informed

We offer two options to keep I-70 travelers informed of current
activity and future plans for the I-70 mountain corridor.

I-70 Alert

The I-70 Alert e-newsletter keeps you up to date on the big picture, including current and future policies, projects, studies and initiatives aimed at fixing I-70. 
Frequency: Quarterly eBlast eBlasts keep you informed on potential impacts and opportunities related to your trips on I-70. These short updates contain timely info on construction projects, new transit options, CDOT winter operations and strategies for beating the crowds.
Frequency: An average of 1-2 times/month