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CDOT I-70 West Vail Pass Design

Project Details



Denver, CO

Client / Owner

Colorado Department of Transportation

Delivery Method


Construction Value

$700 million

West of the Mile High City of Denver, I-70’s Vail Pass reaches 10,662 feet of elevation and passes through the Gore Range of the Rocky Mountains in central Colorado. Steep grades, extreme weather, and mountainous terrain pose significant challenges in the travel and maintenance of Vail Pass, the second highest interstate in the United States. Through a study conducted in 2017, the Colorado Department of Transportation (CDOT) and the Federal Highway Administration (FHWA) completed a detailed analysis to assess improvements to I-70 at West Vail Pass identifying safety and mobility issues. The $700 million I-70 West Vail Pass Auxiliary Lanes project will be constructed to address these concerns via the construction manager/general contractor (CM/GC) delivery method.

Quality services earn trust from clients to design their most complex projects

RS&H’s selection to provide design services for this challenging project is a testament to the quality of services we continue to provide CDOT in completing their most important projects. This 10-mile highly traveled corridor is a critical link for local and regional travel and includes over a mile of complex bridge structures. Improvements include widening five miles of I-70 from two to three lanes, improved shoulders, curve flattening, bridge walls, drainage, signing and striping, ITS, and a recreational trail. Signing improvements include variable speed limit signs and variable message signs that tie to CDOT’s ITS system for altering speeds during inclement weather or congestion. A new segmental 1,000-foot-long curved bridge will be the first bridge built over Polk Creek. RS&H is utilizing experience in providing mountain corridor, CM/GC, and similar design expertise to improve the safety and operations of West Vail Pass.

Incorporating the CSS decision-making process into the design

Over the years, CDOT and stakeholders have invested a tremendous amount of effort and resources toward context-sensitive solutions (CSS) and NEPA. The primary goal of this project is to address safety concerns and operational issues due to geometric conditions (steep grades and tight curves) and slow-moving vehicle and passenger vehicle interactions that result in inconsistent and slow travel times along the corridor. In collaboration with CDOT, stakeholders, and our subconsultant partners, RS&H is blending the design into the I-70 Mountain CSS process to develop solutions that result in the most practical balances of constructability and environmental and stakeholder goals. Through this process, the RS&H team is developing safe, sustainable, context-sensitive design solutions that minimize impacts and blend with the natural beauty of the Rocky Mountains.

Meeting aggressive schedules while maintaining quality

The project was awarded a $140.4 million Infrastructure for Rebuilding America (INFRA) grant with funding tied to fixed milestone completion dates. Since executing this project on schedule and within budget was critical to maintaining funding, RS&H developed multiple construction packages, streamlining the design process to meet milestone dates.

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