This major multi-year expansion project included the planning, designing, and widening of the two-lane US Highway 85 (US-85) to a four-lane configuration for 5 miles, south of the Long X Bridge over the Little Missouri River.  Much of the alignment traverses through Badlands topography, with dozens of large landslide complexes, creating challenging conditions for the highway widening.  This project is the latest phase of a series of projects to widen and improve US-85 through the corridor.

Shannon & Wilson’s services included subsurface exploration and landslide characterization to support the highway widening.  Shannon & Wilson completed numerous phases of geologic reconnaissance and subsurface exploration to characterize large landslide complexes.  Using the data, Shannon & Wilson led the design of major cuts through landslide-prone sedimentary bedrock and anchored drilled shaft landslide stabilization structures using numerical modeling of soil-structure interaction.

Shannon & Wilson has proudly assisted on this highway expansion project throughout its various phases since 2014, including performing a multiple subsurface exploration and laboratory testing program, completing remote sensing to characterize landslides, preparing a landslide inventory and geological hazard assessment studies for the corridor, developing landslide stabilization designs, providing geotechnical design recommendations for the Long X Bridge replacement, and providing construction observation and support services.