South Dakota DOT Opens Key Highway Intersection - 11/8/2024 AASHTO Journal
The South Dakota Department of Transportation recently hosted an event highlighting the partial opening of Diverging Diamond Interchange or DDI where I-229 and Benson Road converge in Sioux Falls.
The agency said in a statement that intersection is now functioning in each direction as a one-lane DDI, with additional lanes of traffic through the interchange slated to open before the entire project is completed in June 2025.
Sometimes called a “double crossover diamond,” DDIs are grade-separated interchanges where traffic between highways and smaller routes crosses to the other side of the roadway between the freeway ramps. That allows vehicles to turn left onto and off freeway ramps without stopping or crossing opposing lanes of traffic.
The South Dakota DOT said this particular DDI is part of a larger $33.6 million project aimed at enhancing safety, reducing intersection delays, and addressing future travel needs and growth where I-229 and Benson Road meet.
The agency added that the new interchange features three left turn lanes on the I-229 northbound off-ramp and dual right turn lanes. Project elements include bridge rehabilitation and widening, on and off-ramp improvements, pedestrian walkway enhancements, and new traffic signals and lighting.