Not just a highway: the exceptional I-70 through Vail Pass and Glenwood Canyon

Posted in: Cultural Resources

West of Denver, two segments of I-70 through Vail Pass and Glenwood Canyon have been labeled as exceptional sections of the Interstate Highway System. Mead & Hunt recently prepared in-depth historic contexts to better understand what makes these segments exceptional for the Colorado DOT to use in future Section 106 compliance efforts. In addition, we found that both segments are eligible for the National Register of Historic Places.

What makes these two highway segments historic? Yes, they are remarkable for their scenery, but this designation is largely due to the highway’s complicated and innovative engineering and design, which deftly incorporates the surrounding natural beauty.

Vail Pass

On Vail Pass, a careful integration of the surrounding natural area into the highway engineering design means that vehicles seemingly float above the landscape. The bridge design emphasizes horizontal lines of the superstructures and unobtrusive piers.

Steel tub girders on Vail Pass have a high span to depth ratio, resulting in a slim-line appearance.
The segmented concrete box girders on Vail Pass—the first of their kind in Colorado—add strength to the beams and girders so the bridges could support larger loads with shallower depths.
Unique scalloped retaining walls designed for Vail Pass by Taliesin Architects blend into the landscape. All of the walls and bridges are finished with iron oxide to create a reddish-pink hue to match the natural outcroppings of the Vail Valley.

Glenwood Canyon

The high walls and narrow width of Glenwood Canyon greatly inhibited access, so designers developed a graceful, terraced roadway celebrated for curtailing environmental impacts.

The use of bridges and viaducts in Glenwood Canyon with tall open piers for drainage, instead of the typical major fill and culverts, allows wildlife to safely cross the highway beneath the structures.
Pier cap designs integrated into the exterior girders of bridges in Glenwood Canyon make the outer girders appear to float between piers.
Aesthetic rock treatment below structure
Preserving the natural features throughout Glenwood Canyon included keeping this rock outcropping beneath one of the viaducts.

This careful integration and preservation of the natural landscape through innovative design techniques are what really stand out here. The characteristics that make these segments unique also require careful Section 106 consultation to consider the impact future transportation improvements will have. These segments through Vail Pass and Glenwood Canyon are just a few of the historic highway corridors we will be writing about in our historic highway blog series.

Dianna Litvak

About the Author

Dianna Litvak is a public historian who specializes in surveying overlooked historic properties such as irrigation ditches, railroad grades, and roads.  Her favorite recent projects include writing about building I-70 through Glenwood Canyon and Vail Pass, and researching the history of meatpacking at Denver’s Union Stock Yards.  When she isn’t reading or writing about history, Dianna loves to hike, cook, and travel.

Read more posts by Dianna Litvak

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