South Dakota Highway 46 stretches more than 100 miles across the state’s southeast corner, running from the Missouri River all the way to the Iowa border. Along this corridor, the South Dakota Department of Transportation (SDDOT) and general contractor Foothills Contracting are working on a large section of the road. The 15.5-mile-long project runs from the eastern edge of Beresford, South Dakota, to just north of the Iowa border.
The project area had an average daily traffic (ADT) of 1,940 in 2022, with 21.6 percent of the total ADT being truck traffic.
The surfacing on this portion of S.D. Highway 46 was nearing the end of its lifespan, so SDDOT planned to upgrade the roadway. During the planning discussions, the team decided to regrade the entire project to add passing sight distances and widen the shoulders.
The grade — including the installation of the in-place culverts — for this segment was originally constructed in 1955.
“The grade and surfacing were all the same age and needed upgrading,” said Greg Rothschadl, Yankton Area Engineer for SDDOT. “The deficiencies that are being resolved with this project were seen throughout most of the roadway, and it was decided to proceed with the regrade for the entire 15.5 miles.”
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Because of the significant addition to the scope, SDDOT broke the work into two separate construction projects. The first project is the regrading project. It includes the placement of an interim surface, made up of a prime oil blotter with a heavy chip seal placed on top of it.
This surface will carry the traffic over the winter months when the roadway is open.
Construction on the project began in spring 2024. The target completion date is late 2025 and, as of this writing, the project is on schedule despite a wet 2025 construction season, according to Rothschadl.
The second project involves placing the final surfacing on the entire portion of Highway 46. The final surfacing will be two 12-foot-wide concrete lanes with 2 feet of concrete shoulder, along with 6-foot-wide asphalt shoulder extensions on each side. The total shoulder width will be 8 feet. SDDOT scheduled this project to begin in 2026.
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The regrading portion of the project involves flattening the profile of the roadway to provide better passing sight distance. The team is also widening the shoulders from 4 to 8 feet.
New permanent signing will be placed upon the completion of the project. The signs include all regulatory, warning, guide, and general information signs.
The team will also replace all the culverts and structures within the project area.
The project, called S.D. Highway 46 - From Beresford to Iowa State Line, is a typical grading project for SDDOT, Rothschadl noted. The department is regularly working on a dozen or more projects similar to this one at any given time. So, the team is very familiar with all elements of a project like this one.
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The equipment utilized on the project is standard, including scrapers, dozers, blades, backhoes, disks, and trucks.
What makes the Highway 46 project stand out from others is the sheer size of it. “The main challenge is the overall size and length of the project,” Rothschadl said.
The project requires the team to move almost 2.4 million cubic yards of dirt, place 15,000 feet of new culverts, lay down 265,000 tons of granular surfacing, and replace seven structures with new concrete box culverts.
The surfacing project will place 272,465 square yards of 8-inch-thick non-reinforced concrete pavement with 163,000 dowel bars on the mainline, as well as 25,000 tons of asphalt pavement on the shoulders.
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The project’s great length has also had an impact on phasing and scheduling. SDDOT split the grading portion of the project into three phases.
“The SDDOT anticipated that the project was too large to complete in one year, so we needed a break point between year one and year two,” Rothschadl said. The department chose S.D. Highway 11 as that break point.
“This north-south state highway is exactly in the middle of the project, so it was a natural break point,” Rothschadl said. “Our planned detour route for the east-west leg was a county highway 3 miles north of the project, and breaking the project in the middle allowed the SDDOT to use half the detour route each year.”
Phase three is the far eastern 1.5 miles that runs north-south, just north of the Iowa border.
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Unlike the earlier phases, there is no viable detour for this portion. Therefore, SDDOT broke it out into its own phase.
“The contractor is constructing it a half-width at a time while traffic is being maintained on the other half,” Rothschadl said. “The construction of phase three was allowed in either year one or year two, and Foothills Contracting decided to construct it in year two.”
The team constructed the first phase (from Beresford to Highway 11) in 2024. Phase two (which is from Highway 11 to the eastern curve) and phase three are being constructed concurrently in 2025.
Since this project is on an active highway, there is also the challenge of dealing with traffic. The department closed the highway to through traffic during phase one and phase two. However, the highway is open to traffic during phase three.
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“The first two phases required heavy grading, with too many large cuts and fills to try to carry highway traffic through,” Rothschadl said. This is not the case in phase three.
The department and the county created a detour that minimizes disruption for drivers.
“The detour agreement, which was worked out between SDDOT and Lincoln County, utilizes a portion of the county highway system,” Rothschadl said.
The detour adds 6 miles to drivers’ routes, 3 miles north and then 3 miles back south to Highway 46. Rothschadl estimates that the detour will add less than 10 minutes to the commute.
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“It keeps the traveling public away from the construction for most of the project, which allowed for a safer driving experience for motorists and for the workers,” he said.
The SDDOT website says that “access to residents and landowners adjacent to the project will be maintained, but travelers are encouraged to use the signed detour route around the project.”
The east-west leg of the detour ran the whole 12 miles of the project.
Foothills Contracting, which is located 2.5 hours north of the project area, has a long-standing relationship with SDDOT. The grading contractor has constructed many projects in the southeast corner of South Dakota over the life of the company. The current project is the fourth that Foothills has constructed with the Yankton Area SDDOT since 2018.
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“They’re a very knowledgeable grading contractor, have the right equipment, and trained personnel to complete the project,” Rothschadl said.
The construction budget for the grading portion of the project is $24.8 million. Currently, the project is on budget.
“Good planning, a good set of plans, and a good contractor have helped this project stay on budget,” Rothschadl said. “Also, SDDOT project staff and the contractor staff have a very good working relationship based on vast experience working together on past projects.”
He added that it was helpful to take part in early stakeholder engagement with Lincoln County and Poet Bioprocessing, located near Hudson, South Dakota, less than 1 mile from the project.
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SDDOT estimates the 2026 surfacing project will cost $29.1 million.
SDDOT’s Statewide Transportation Improvement Program (STIP) process is funding both projects. Federal funds are used in the SDDOT STIP.
When the team completes the project, the traveling public will have better passing sight distances and safer passing opportunities. The wider shoulders will allow more room for stranded or stopped vehicles to completely get out of the driving lane and out of the way of travel. Finally, the new concrete mainline will provide a smooth surface and a pleasant ride for the traveling public.
The current project on Highway 46 is the final of four total grading/surfacing projects that extended from the Iowa border west to U.S. Highway 81 north of Yankton, South Dakota. The total length of these four projects was 48 miles. The first project began in 2020, and the last remaining project on the entire 48-mile corridor is expected to be completed in 2026. The cumulation of these four projects will significantly enhance the safety of the traveling public throughout the whole area, along with making it safer and more efficient for freight to be moved through the region.
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- Owner: South Dakota Department of Transportation
- General Contractor: Foothills Construction, Webster, South Dakota
- Grading Project Subcontractors: BX Civil & Construction, Dell Rapids, South Dakota; Prunty Construction Company, Brookings, South Dakota; The Road Guy Construction Co., Yankton, South Dakota; Midstates Reclamation Inc., Lakeville, Minnesota; Northwest Landscaping Inc., Hull, Iowa; Traffic Solutions Inc. AKA Sir Lines-A-Lot, Sioux Falls, South Dakota; Brosz Engineering, Sioux Falls, South Dakota
