Three-Span 120-foot Continuous Concrete Bridge

Owner: Moody County Highway Dept.
Location: Flandreau, South Dakota

Civil Design Inc. was the engineer chosen by the Moody County highway department to design a replacement bridge over Pipestone Creek in eastern South Dakota. An overloaded truck caused the in-place pony truss structure to collapse, necessitating the replacement bridge.

CDI performed the hydraulic analysis to size the opening of the new structure as well as the hydraulic survey. We then presented the South Dakota Department of Transportation (SDDOT) and Moody County highway department with four alternatives that met the criteria for the replacement structure. The government entities chose the three-span continuous concrete structure with sloped abutments as the most economical and expedient choice. CDI performed the structural design, prepared the plans and specifications for construction, and provided shop drawing review and advice during construction. The SDDOT performed all construction administration duties on this project.

One particular design modification on this project included raising the elevation of the bridge to accommodate a design flood. CDI completed construction plans for the bridge, including the grading design. CDI also assisted during construction by offering technical advice to the SDDOT field engineer.