Community Partners Celebrate New Interchange Groundbreaking - City of Sioux Falls

After more than a decade of planning, construction is set to begin on the new diverging diamond interchange (DDI) at 85th Street and Interstate 29. Representatives from South Dakota’s congressional delegation, the State of South Dakota, the City of Sioux Falls, City of Tea, Lincoln County, Sioux Falls Development Foundation and a group of property owners from the area celebrated the project with a groundbreaking ceremony on Tuesday, Nov. 25. 

“I have been looking forward to this groundbreaking since the day I took office,” Sioux Falls Mayor Paul TenHaken said. “A collaboration like this takes time, but the transformational result of this project is well worth it. I can’t say enough about the partners involved in this effort that helped make it a reality.” 

The $54.4 million interchange will connect 85th Street from the east, in southwestern Sioux Falls, to the west side of I-29, in Tea. Along I-29, the new interchange will be located between the exits at Highway 106 and Interstate 229. The project will include the construction of a DDI, like the one at 41st Street and I-29, and a pedestrian and bicycle underpass, and installation of underground utilities, signage, streetlights, and traffic signals. 

“Southeastern South Dakota is rapidly growing, and we are making significant investments to ensure our transportation network is connected, efficient, and safe for commuters,” South Dakota Department of Transportation (SDDOT) Secretary Joel Jundt said. 

This will be the first new interstate interchange in Sioux Falls in 15 years. The last new interchange was constructed at Marion Road and Interstate 90 in 2010. This will also be the third DDI for Sioux Falls, in addition to those at 41st Street and I-29 and Benson Road and I-229. DDIs improve traffic flow and safety by reducing traffic conflict points. 

Several public and private partners were involved to move the project forward, both logistically and financially, including the Federal Highway Administration, SDDOT, City of Sioux Falls, City of Tea, Lincoln County and a group of property owners in the area. South Dakota Sen. John Thune was instrumental in securing $30 million in federal funding for the project. 

The need for the interchange was identified years ago through several community and transportation planning documents, including the City’s Shape Sioux Falls comprehensive development plan, Sioux Falls Metropolitan Planning Organization’s 2050 transportation plan, Tea comprehensive plan, and Lincoln County master transportation plan. The first official approval for the project came in late 2014 when the Lincoln County Commission supported a memorandum of understanding with the SDDOT for the county’s financial commitment to the project. From there, teams moved the project through land annexation approvals, right-of-way procurements, reports, grant applications and eventually an environmental assessment that was completed in March 2023. Following that critical approval, the team developed the interchange design, funding package and bid the project in mid-October of this year. The project is expected to be complete by the end of 2027.