U.S. Highway 12 - S.D. Highway 1806 and S.D. Highway 63
Project Summary:
U.S. Highway 12 - From 12 Miles East of McLaughlin to West of Mobridge
Full-depth reclamation and asphalt concrete surfacing on U.S. Highway 12 is being done to eliminate the existing reflective cracking and rough joints on the existing road. Undercutting and subgrade reconstruction through the heave area on S.D. Highway 1806 is being done to eliminate the existing pavement heaving and restore a normal crown to the highway. This work, combined with the milling and asphalt concrete resurfacing of S.D. Highway 1806, S.D. Highway 1806P and S.D. Highway 63 will restore a normal crown to the highways and provide for a smooth pavement surface. Guardrail is being replaced on all routes with bridges to improve safety, and culverts are being repaired as necessary to ensure proper drainage and extend the life of the roadway.
U.S. Highway 12
Work on the highway will include 3-4” of Cold Milling followed by reclaiming of 3-5” of inplace asphalt concrete and 4-5” of granular material. Once this material is reshaped and compacted, 4-5 ½” of Asphalt Concrete will be placed.
S.D. Highway 1806
Heave Area repair (south of bridge over railroad) will include removal of the top 3 feet of surfacing and subgrade material, reworking and compacting the subgrade material, placing 9” of Base Course and finally resurfacing with 4” of Asphalt Concrete.
S.D. Highway 1806 south of U.S. Highway 12, S.D. Highway 1806 north of U.S. Highway 12, S.D. Highway 1806 Spur Route to Wakpala, and S.D. Highway 63 north of McLaughlin
Resurfacing of these four routes will include 1” of Cold Milling followed by one 2” lift of asphalt concrete.
All Routes
Culvert repair will be done on all five routes and guardrail will be replaced at all bridge locations.
Project Timeline:
June 2025 - Nov. 2025
Project Updates:
Sept. 19, 2025:
Extremely heavy rainfall in north-central South Dakota over the past several days has impacted the temporary gravel surface on U.S. Highway 12 west of Mobridge. Motorists should be aware that this portion of Highway 12 is rough and contains many potholes caused by the adverse weather conditions. Travelers are urged to reduce their speed to 25 miles per hour or slower through this area.
With the rain anticipated to subside over the weekend, the contractor will begin maintaining the temporary gravel surface and driving conditions are expected to improve.
Pictured are the road conditions as of Friday, Sept. 19, 2025.
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Sept. 15, 2025:
Aug. 15–Sept. 15, 2025 — Completed work: Cold milling and base course placement began on the west end of the project Sept. 2 and has progressed to the S.D. Highway 20 junction (9.6 miles). Full-depth reclamation began at the west end Sept. 5, with 3.4 miles completed.
Shoulder widening at the U.S. Highway 12 and S.D. Highway 20 junction is also underway.
Sept. 15–Oct. 15, 2025 — Anticipated work: Cold milling and base course placement will continue from the east end of the project (Missouri River bridge) to the S.D. Highway 20 junction. Full-depth reclamation will follow. All cold milling, base course placement and reclamation work are scheduled for completion within this period.
Culvert replacement, pipe work and slide repairs on S.D. Highway 1806 south of U.S. Highway 12 are also planned.
Asphalt paving on U.S. Highway 12 is scheduled to begin the last week of September.
Project Photos:
Project Contract Amount:
$24.1 Million
Project Contacts:
SDDOT:605-961-4930
Contractor:
Central Specialties
Alexandria MN
