SIOUX FALLS, SD — South Dakota Department of Transportation (SDDOT) Secretary Joel Jundt and Sioux Falls Mayor Paul TenHaken were joined by federal, state, and local leaders to highlight the opening of the Interstate 229 and Benson Road Diverging Diamond Interchange (DDI) in Sioux Falls, South Dakota. The interchange is now functioning in each direction as a one-lane DDI. Additional lanes of traffic through the interchange will be open before the entire project is completed in June 2025.

This project was developed through a coordinated effort by SDDOT, the City of Sioux Falls, and the South Dakota Division Office of the Federal Highway Administration. The DDI will help enhance safety, reduce intersection delays, and address future travel needs and growth. The project includes more than $36.3 million in roadway improvements. 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.

Staff from South Dakota’s federal delegation participated in the ribbon cutting. Also present were Sioux Falls elected officials, state legislators, South Dakota Transportation Commission members, SDDOT planning and engineering staff, SDDOT operations staff, and T & R Construction staff who served as the primary project contractor.

Diverging Diamond Interchanges are shown to increase capacity and safety, reduce congestion, and minimize the cost of new infrastructure. Additional advantages include:

• Improved safety by reducing the number of vehicle conflict points
• Increased capacity by eliminating the left turn signal and allowing traffic to flow more efficiently through the interchange
• Reduced delays and congestion
• Advanced ability to meet the needs of all motorists, pedestrians, and bicyclists
• Reduced construction costs due to smaller bridges