The structure work on this South Dakota Department of Transportation project consisted of the total reconstruction of the existing interchange, while keeping traffic flowing. SFC Civil Constructor’s portion of the project was to tear out and replace two existing interstate bridges with two new structures.
The new structures are 374 feet long, 42 feet wide composite bridges. The substructure is composed of two abutments and two bents, each founded on driven pile foundations. The bent structures are single piers holding a single cap spanning the full 42 feet width. To achieve the finish required with the complex geometric design of the piers and caps, each bent unit was poured monolithically. The bent units were placed with Self Consolidating Concrete to give a superb finish and to achieve design strength early to allow the placing of the steel girders as quick a possible.
The superstructure is comprised of five lines of 6 feet deep weathering steel girders. An 8.25 inch cast in place concrete deck finishes the driving surface.
Each bridge was completed in three months from demolition of the old bridge to placing traffic on the new one, and in one construction season.