The Norris Viaduct was a 51-year-old, structurally deficient crossing over the Union Pacific Railroad tracks. The obsolete viaduct was one of only four crossings between south and north Cheyenne. Replacing this major trafficway would tremendously affect the economy and social practices for the City of Cheyenne and its citizens.
Olsson Associates was chosen to provide preliminary design, final design, and construction phase services for replacing the viaduct. Olsson’s analysis determined that traffic volumes on the streets approaching the viaduct were slightly above capacity, causing delays and accidents in the neighborhood.
The project team also devised an interactive public involvement process for evaluating the alternatives. Through this process, the city was able to engage the public in selecting an alternative that would enhance the neighborhood, the environment, and transportation in Cheyenne.
In addition, this project included completing an environmental assessment (EA), whereby the team analyzed different alternatives and evaluated the social, economic, and environmental impacts of each alternative. Other environmental components provided for the project included wetland delineation and mitigation, threatened and endangered species assessment, noise analysis and abatement, and Section 106 resource coordination. Olsson also provided an environmental justice evaluation, a 4(f) assessment, and hazardous material analysis. The EA was completed in 2005 and Olsson proceeded to final design.
The project that was eventually constructed became the largest public works project in the city’s history. The alternative selected replaced the viaduct and widened and reconfigured the streets, improving safety and revitalizing the neighborhood. Further, the approaches and viaduct were designed with trail users in mind to provide a visually pleasing crossing over the UPRR mainline tracks while keeping users safe and meeting the railroad’s stringent requirements. The design also created several green spaces and pocket parks and extended the Crow Creek Greenway, which is a link in the City's hiker/biker trail system.
For its efforts and expertise on this project, Olsson Associates won the Wyoming Engineering Society’s 2010 Presidential Project Award.