Interstate 29 and 85th Street Interchange in Sioux Falls
Project Summary:
The project includes construction of a Diverging Diamond Interchange (DDI), structure development work, grading, concrete surfacing, curb and gutter, storm sewer, lighting, signals, permanent signing, and pavement marking.
Travel Impacts: Traffic will be maintained with two lanes open in each direction on I-29 during peak travel hours. Peak hours are defined as 6:30 a.m. to 9 a.m. and 3:30 p.m. to 6 p.m.
Business Access: Access will be maintained at 85th Street and Sundowner Avenue and Tall Grass Avenue.
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Project Updates:
July 15, 2026:
On Thursday, July 16, 2026, the southbound lanes of Interstate 229 will be closed from 12–3 a.m. at mile marker 0, the south end of I-229, in Sioux Falls to move a crane.
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July 10, 2026:
On Wednesday, July 15, 2026, the southbound lanes of Interstate 229 will be closed during the overnight from 12–3 a.m. in Sioux Falls at mile marker 0.
Southbound I-229 traffic will be directed to northbound Interstate 29 exit 77 (41st Street) then to southbound I-29. Drivers should follow posted signs and arrows through the work area.
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June 30, 2026:
Anticipated Work in July 2026:
The contractor will continue grading 85th Street east and west of Interstate 29.
The contractor will drive piling for the south footing of Bent No. 2 at the 85th Street and Interstate 29 interchange.
The contractor will form, install reinforcing steel and place concrete for the center and north footings of Bent No. 2 at the 85th Street and Interstate 29 interchange.
View 85th Street updates on the City of Sioux Falls website: I-29 & 85th Street Interchange - City of Sioux Falls