Interchange on the I-90 Brandon exit officially opens

BRANDON, S.D. (Dakota News Now) - The brand new diverging diamond interchange at exit 406 is officially open in Brandon after several years of construction.

Tuesday’s ribbon-cutting ceremony marked a major milestone for Brandon, bringing safer traffic flow and a whole new look to one of the busiest entrances into the city.

Construction began in April of 2024, and the South Dakota Department of Transportation communicated closely with local businesses and the city to figure out how to best accommodate the traffic.

Changes include more lighting and signals, reconstructing three bridges, and creating the diverging diamond configuration.

“Our bridges are now designed for 75 to 100 years, so that will go beyond my lifetime,” said Joel Jundt, the SDDOT Secretary of Transportation. “I will not be out here again with you guys to do this. But this is our fourth diverging diamond called DDIs.”

The total cost of the project was $41.3 million. The DDI allows drivers to make left turns without crossing upcoming traffic, and turns are also free-flow.

“We dealt with a few issues that we ran into, which were minor looking back at the time, seemed like large hurdles,” said Harry Johnston, Sioux Falls DOT Area Engineer. “But with our communication and just being able to talk through the issues, work through them, and make it a successful project at the end, the collaboration was great.”

The diverging diamond completed in Rapid City in 2023 has seen a 54% reduction in crashes, and there has been a 75% reduction in crashes at the 41st Street interchange in Sioux Falls, so safety has always been a goal.

“The bridge that we had before, the exit, was really outdated, especially if you were coming from the east and going west and then had to get off at the exit and then turned south,” said Mayor Harry Buck of Brandon. “It was kind of dangerous. So this new bridge is really terrific. I understand that we’re one of the first, you know, non-big metro areas that has a divergent diamond.”

The South Dakota Department of Transportation said crews will still be out here working to finish final field work through June. However, the major construction for drivers is over, and the interstate is officially open.