I-29 & 85th Street Interchange

• Project value$54,443,975
• Contractor nameT&R Contracting
• Completion DateDecember 31, 2027

The City of SIoux Falls, in conjunction with the City of Tea, Lincoln County, and the SDDOT, has started constructing the new diverging diamond interchange at 85th Street and I-29.

The project includes building the interchange and installing underground utilities, a pedestrian underpass, grading, concrete surfacing, signage, street lighting and traffic signals.

Project Update: 03/16/2026

• A Pre-construction meeting is scheduled on March 10, 2026.
• Public open house is scheduled for March 19, 2026, from 5:00 pm to 6:30 pm at Sioux Falls Lutheran School (6715 S. Boe Avenue, Sioux Falls, SD).
• Contractor is scheduled to install the water main casing under the I29 during the week of March 16, 2026.
• Contractor is currently working on grading, installing piles, and installing bridge abutments for the southbound exit ramps.

Commuter Route Information

• 85^th Street from Tallgrass Avenue to Sundowner Avenue will be closed to traffic. Access will be maintained for local residents only.
• I-29 traffic to remain in place during construction. Lane/shoulder closures will be allowed for work adjacent to existing lanes.
• Partial closures of I-29 will be allowed overnight for bridge or MSE wall construction.

Additional Information

Project Milestones

Year 1 - Phase 1A

1. Traffic Control
2. Removals
3. Watermain
4. Grading
5. Geofoam Over L&C Watermain
6. Bridge Abutment
7. Bridge Pier
8. Grading Pumps

Year 1 - Phase 1B

1. Grading Bridge Abutment
2. Geofoam Over L&C Watermain
3. MSE Wall
4. Grading Pumps

Year 1 - Phase 1C

1. Final Grading
2. I229 Grade Widening at Ramp 1C
3. Excavation for Ramp 1C

Year 2 - Phase 2A

1. Ramp Paving
2. Bridge Construction
3. Storm Sewer

Year 2 - Phase 2B

1. Graveling
2. Curb and Gutter
3. Concrete Surfacing

Year 2 - Phase 2C

1. Lighting
2. Decorative Landscaping
3. Pavement Markings
4. Restoration
5. Open to Traffic