Interstate 90 - Exit 406 (Brandon)

Project Summary:

This project includes the reconstruction of exit 406 (Brandon) with added lighting, signals, and mainline Interstate work. This project also includes three structure replacements.

The interchange will be reconstructed as a diverging diamond configuration.
Westbound Interstate 90 lanes (along with the railroad structure on I90) will be reconstructed in 2024 and the eastbound lanes (and railroad structure in 2025). The interchange itself and new structure over I90 will be reconstructed between 2024 and 2025.
S.D. Highway 11 traffic will be maintained across Interstate 90 during construction.
The westbound on-ramp and eastbound off-ramp are expected to be open to traffic for the majority of the project. Closures for the westbound off-ramp and eastbound on-ramp are planned for 2025.
Work will extend on S.D. Highway 11 down to Redwood Boulevard. That work includes adding a shared use path on the west side, approach and side street work, a retaining wall on the east side north of Ash St, and other items.

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Project Timeline:

Spring 2024 - Substantial completion is scheduled for Nov. 21, 2025, with final field work completion set for June 2026.

Project Updates:

Nov. 18, 2025:

Oct. 15, 2025 – Nov. 15, 2025, Completed Work:
Median grading is nearing completion with topsoil placement. The DDI signals are fully functional, and most permanent pavement markings through the interchange are complete. The eastbound lanes have been paved and joint sealing is finished. Most median and ramp lighting has been installed. All guardrail work on the eastbound lanes is complete and the area is ready for single-lane closures as remaining work continues.

Anticipated Work Nov. 15, 2025 – Dec. 15, 2025:
Remaining median grading and the south slope of the eastbound lanes will be completed, along with ROW fencing, seeding, and mulching. The remaining median lighting is expected to become operational shortly after the eastbound lanes open to traffic. The majority of signing should also be completed.

Key Dates:
Substantial completion is scheduled for Nov. 21, 2025, with final field work completion set for June 19, 2026.

Oct. 31, 2025:

On Thursday, Nov. 6, 2025, the northbound S.D. Highway 11 to eastbound Interstate 90 exit 406 (Brandon) on-ramp will be temporarily closed for approximately four hours beginning in the afternoon. There will also be a second temporary ramp closure at the westbound I-90 exit 406 off-ramp to southbound Highway 11 for approximately four hours. Both scheduled ramp closures are weather dependent and subject to change.

Both closures are needed for crews to place permanent pavement markings. Message boards will be placed around the work zone to alert motorists of the closure.

Navigating a DDI:

Sample video of how to drive a DDI (sample provided demonstrates the DDI located at 41st Street in Sioux Falls which features three lanes). I-29 41st St DDI Animation - YouTube

Drivers follow the signs, signals and pavement markings to cross through the intersection at the first set of traffic lights. Traffic appears as if on a one-way street.
All left turns onto the freeway are free flow, meaning vehicles do not have to stop to access the ramp.
Vehicles going straight simply proceed through a second set of traffic lights.
Pedestrians travel on designated walkways and cross only at the crosswalks.
Bicyclists may choose to use the bike lane or pedestrian walkways and crosswalks.