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 - Spring 2026
Project Updates:
Oct. 31, 2025:
Sept. 15, 2025 – Oct. 15, 2025, Completed Work:
U.S. Highway 12: Cold milling and full-depth reclamation have been completed. Widening work is finished at the U.S. 12/S.D. 20 and U.S. 12/S.D. 1806 junctions. The first lift of asphalt concrete has been placed for approximately five miles west of the S.D. 20 junction. Culvert end treatment repairs are in progress.
S.D. 1806 south of U.S. 12: Pipe replacements have been completed.
S.D. 1806 north of U.S. 12: No work has been completed in this section.
S.D. 1806 spur to Wakpala: No work has been completed in this section.
Anticipated Work Oct. 15, 2025 – Nov. 15, 2025:
The contractor will complete final shaping, priming, and paving of the first lift of asphalt concrete on the U.S. 12 section. Culvert repair work will also be finished in this area. Slide repair work may begin on S.D. 1806 south of U.S. 12. No additional work is anticipated for the remainder of the season.
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Oct. 9, 2025:
On Wednesday, Oct. 8, 2025, an unplanned construction need developed on the current project located on U.S. Highway 12 near the bridge over Snake Creek, approximately eight miles west of Mobridge. Crews are working to repair the impacted area on the west end of the bridge.
Crews are currently working on the eastbound lane of the bridge. Traffic is being controlled through the use of flaggers and a pilot car in the westbound lane. There is an 11-foot width restriction in place through the work zone. Work will transition to the westbound lane of the bridge once crews complete the necessary repairs in the eastbound lane.
Due to the immediate response needed for this project, there is no work zone signage in place. Motorists are asked to find alternate routes around the work area at this time.
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Sept. 23, 2025:
U.S. Highway 12 west of Mobridge was reshaped by the contractor on Saturday, Sept. 20, 2025. Pictured below is the condition of the new temporary gravel surface taken the morning of Tuesday, Sept. 23, 2025.
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.
Project Photos:
Project Contract Amount:
$24.1 Million
Project Contacts:
SDDOT:605-961-4930
Contractor:
Central Specialties
Alexandria MN
