05/20/2026
What say you folks? That's a lot of money...
Piedmont I90 interchange
will be most expensive
SDDOT project in its history
PIERRE, S.D. (KELO) — Reconstruction of an Interstate 90 interchange between Rapid City and Sturgis will cost more than $77 million and would be the most expensive single project undertaken in the history of the South Dakota Department of Transportation.
The state Transportation Commission on Friday awarded the contract for work on what’s known to motorists as the Piedmont Exit 46 exit to Heavy Constructors Inc. of Rapid City.
But state Transportation Secretary Joel Jundt told the commission that the project’s top status will be short-live.
That is because the department that Jundt leads will seek bids later this summer to replace the SD Highway 44 bridge that spans the Missouri River in south-central South Dakota.
The bridge is more than a mile long and serves as the most direct route between the city of Platte in Charles Mix County and the city of Winner in Gregory County. Replacing it will cost upward of $200 million. The actual estimated cost will be released after contractors submit bids.
SDDOT roughly estimated the cost of replacing the Platte-Winner bridge at $258,342,000 as part of an application for federal aid. The project recently received a $65 million federal grant. South Dakota’s two U.S. senators, Republicans John Thune and Mike Rounds, had earlier secured $25 million for the project as part of an appropriations package.
The Elk Creek Road interchange on I-90 serves the growing communities of Summerset and Piedmont in Meade County. Heavy Constructors was the lowest of the three bidders at $77,697,290.36. That was $6,940,373.94 or 9.8% more than DOT’s estimated project cost of $70,756,916.42.
The commission on Friday awarded 11 projects from SDDOT’s May 6 bid openings and nine projects from the May 13 bid openings. The commission also rejected all bids on one project that will be reconfigured and re-let later.
After the commission concluded its business, Jundt asked the department’s bid presenter, Sam Weisgram, where the I-90 exit project ranked.
“Dollar-wise we believe that 78 million (dollars) is the largest,” Weisgram said.
Jundt said the I-90 interchange project has been in the works for a while. “I think it was a milestone for us,” Jundt said about the amount.
Commissioner Ron Rosenboom of Sturgis lives in the project’s area. “The people in Piedmont will be pleased, I believe, they’re getting that upgrade to that site. It’s been kind of a long haul on that,” he said.
“It will take us three years to get it done. All hands on deck as we move forward,” Jundt said.
“Kind of cool to see it all come together,” said the commission’s chair, Austin Simons of Mobridge.
KELOLAND News received additional information from the department Friday afternoon.
The largest single contract previously was the I-90/Veterans Interchange (Exit 402) project, which extended from I-90 to Rice Street in the Sioux Falls area. That project was bid in November 2017, with the low bid award of approximately $54 million.
Work on the I-90 Exit 46 project could begin this summer, but no work that affects I-90 traffic will be allowed prior to Monday, Aug. 17, 2026, unless approved by the SDDOT. The overall field work completion date is set for Tuesday, Dec. 1, 2028.
Currently, according to SDDOT, the Platte-Winner bridge project is programmed for $255 million. This estimate reflects all project costs, not solely anticipated construction costs.
The anticipated bid advertisement is expected on Friday, June 5, 2026, with the bid opening on Wednesday, July 29, 2026. The Transportation Commission will consider award of the bid in August at a date yet to be determined.
