Platte-Winner Bridge Corridor Study + Environmental Assessment

The South Dakota Department of Transportation (SDDOT) identified a need to replace the SD 44 Bridge over the Missouri River (the “Platte-Winner Bridge”). This is the longest bridge in South Dakota, spanning the Missouri River over a total length of approximately one mile. Key environmental challenges include deep foundations in the river, unstable geology in the adjacent valley where landslides routinely occur, and the presence of a popular state park on one end of the Platte-Winner Bridge.

HR Green worked with SDDOT to develop a Corridor Study identifying a new location and bridge type. The identified location was developed through extensive agency coordination, including FHWA, U.S. Army Corps of Engineers, SDDOT, and South Dakota Game, Fish, and Parks (SDGFP).

Key steps to the Platte-Winner Bridge location determination included finding a geotechnically suitable location, addressing federal regulations around historic cultural resources (Section 106), and mitigating impacts to recreational resources per Section 4(f) regulation.

Ongoing agency coordination has created several benefits toward the anticipated start of construction in 2024. As part of the environmental review, HR Green helped develop a Memorandum of Agreement (MOA) for the management of study and construction activities that require cooperation with historic and tribal officials for monitoring ground disturbances. Consultation with SDGFP has also established an agreement for new and relocated recreational resources at Snake Creek Recreational Area.

These agency and stakeholder coordination efforts have helped to prepare all parties for efficient construction of this regionally significant river crossing.