Under the Section 106 regulations, when a project is determined to have an adverse effect to an eligible or listed resource, CDOT is required to mitigate that adverse effect. This mitigation can take a variety of forms, from reports that provide historical and photographic documentation of a resource, to interpretive signs, to museum displays. CDOT strives for creative mitigation options that address the adverse effect while providing engaging tools that inform the general public about Colorado’s history. Highlighted below are some of the products that have been developed as part of mitigation.


Forging the West

Historic Pueblo Inc. spearheaded the effort to develop this documentary-length film about the history of the Colorado Fuel & Iron Company (CF&I), which was built in 1872 and was the first steel mill west of the Mississippi River. Developed by HaveyPro Cinema, this film use historic images and interviews with current mill employees to tell the story of this important historic resource. CDOT provided partial funding for the production of the film as part of its mitigation for adverse effects to historic properties related to the reconstruction of Interstate 25 through Pueblo, which includes the historic steel mill complex located east of the highway. For more information about this film, visit the Historic Pueblo website.

Moving Mountains: Colorado’s First Interstate Tunnels

This short film was funded by CDOT as part of the Section 106 mitigation for the Twin Tunnels Environmental Assessment, which evaluated the widening of the eastbound bore of the historic Twin Tunnels complex along Interstate 70 (I-70) just east of Idaho Springs. The Twin Tunnels were completed in 1961 and are historically significant as the first successful tunneling operation associated with the construction of I-70 and as an important early milestone in the construction of the highway through Colorado’s Rocky Mountains. The film examines the movement to build the interstate connection west of Denver and the effect of the highway on adjacent communities, including Idaho Springs. 

Force of Nature: Passage and Preservation from Georgetown to Silver Plume

This short film was funded by CDOT as part of the Section 106 mitigation for a series of rock fall mitigation projects along a 2-mile stretch of Interstate 70 that extends through the Georgetown-Silver Plume National Historic Landmark District. The film examines the history of transportation challenges between Georgetown and Silver Plume and highlights current efforts to address rock fall hazards along this stretch of Interstate 70.

Dolores River Bridge LIDAR/ video

Constructed in 1952, the Dolores River Bridge is a rigid-connected Pennsylvania through truss that was listed on the National Register of Historic Places in 2002. When it was determined that the bridge needed to be replaced, CDOT decided to complete a LiDAR - a three dimensional scan - of the bridge as part of the Section 106 mitigation. The LiDAR scan included a short time-lapse film (COMING SOON) showing the bridge’s features. A time-lapse film of the removal of the bridge truss and the construction of the new bridge was also developed. 


Historic Streetcar Systems of Colorado

The Historic Streetcar Systems of Colorado Study, completed in 2020, documented the history of streetcar systems in cities and towns throughout Colorado. Trolley tracks are often encountered on CDOT projects, and this study will serve as programmatic mitigation for future discoveries of trolley tracks, streamlining Section 106 consultation. The study identified systems in thirteen Colorado communities and developed a historic context that focused on the operations, technologies, alterations, and other research areas associated with each system. It established registration requirements for evaluating National Register of Historic Places eligibility for trolley tracks and created a research guide to aid future investigations into different systems. The study also created an interactive ArcGIS StoryMap that mapped the locations of the thirteen identified streetcar systems and how they evolved over time. 

Bridges of Eagle County

This book was funded by CDOT as part of a broader Section 106 mitigation effort to address the replacement of numerous historic bridges in Eagle County over the years. Written by Kathy Heicher of the Eagle County Historical Society and published in 2015, this book emphasizes the importance of transportation in history of Eagle County, and highlights a select number of notable bridges in the county, including the Red Cliff Arch Bridge and the Wolcott Bridge, among others. The book was the recipient of the Carolyn Bancroft History Project Award in 2016. In their comments, the selection committee noted that it “was especially impressed by the creative approach to federally required mitigation and the engaging design and content of the book itself.” The mitigation approach was also unique because the Memorandum of Agreement (MOA) for the project facilitated a process whereby the Eagle County Historical Society could sell copies of the book for profit. A limited number of books are also available at CDOT for no cost. 

Vail and Glenwood Historic Contexts

In 2006 the segments of Interstate 70 over Vail Pass and through Glenwood Canyon were added to the “Final List of Nationally and Exceptionally Significant Features of the Federal Interstate Highway System” because they were some of the first interstate segments designed to conform to their natural surroundings and environment. Glenwood Canyon, completed in 1992, is located on I-70 from milepost 118.5 to 130.3 and was the “final link” in the construction of I-70 across Colorado. Vail Pass, completed in 1972, is located on Interstate 70 from milepost 180-195.2. In 2019, CDOT completed extensive historic context reports and site forms for each highway segment that detail their development history and environmental design factors. Both segments were identified as linear historic districts, and the site forms detail contributing and non-contributing features, establish official resource boundaries, and evaluate historic integrity. These historic context reports and forms were developed as Section 106 mitigation and were designed to assist CDOT in the management and treatment of these resources when there are future projects along these corridors. 

Denver's Brick Sewers

The Historic Context of Denver's Brick Sewers was completed in 2012 as mitigation for several projects that required the removal of historic brick sewers beneath Denver's roadways. The document gives an overview of the history of the sanitary and storm sewer systems in Denver and details their development, construction, and use. The study also surveyed several extant sewer lines throughout Denver and included an assessment of their National Register eligibility and historic integrity.

Interpretive Material

Interpretive Signage

CDOT designs and installs interpretive signs as part of mitigation commitments. Typically placed alongside highway pull-offs, rest areas, or other locations near roadways, these signs focus on resources and sites that were adversely affected by CDOT projects, such as historic bridges or archaeological sites. Below is a list of some of the signs CDOT has installed across the state. 

Driving Tour Pamphlet

Historian Dianna Litvak authored this brochure entitled Driving Tours of Historic Bridges in Fremont County, and Near Interstate 70 West of Denver, Colorado. The pamphlet features thumbnail photos, location information, maps, and historic background for 12 bridges in Fremont County, and thirteen bridges along the Interstate 70 corridor extending from Vail Pass to Rabbit Valley near the Utah/Colorado border. The brochure was designed for bridge preservationists, local historians, engineering professionals and members of the general public who are interested in visiting some of the state's historically significant bridges.

Adopt-A-Bridge Opportunities

Historic truss bridges are made available for adoption by the public through an adopt-a-bridge process, which is designed to assist in the re-use of bridges scheduled for replacement. Interested adopters are asked to provide a relocation proposal that includes information about proposed use, new location, and maintenance plans.