South Dakota has multiple famous scenic wonders, including the Badlands, the Black Hills, and Mount Rushmore. The land in the state is also suitable for farming, which is South Dakota's largest industry. Transporting the corn, wheat, rye, etc., that are grown in the state requires sufficient well-kept roads. To enhance roadway connectivity in the state and beyond, the South Dakota Department of Transportation (SDDOT) is approaching the conclusion of a project to widen U.S. Highway 18.
U.S. Highway 18 runs east to west from Milwaukee, Wisconsin, to eastern Wyoming and travels through southern South Dakota. The 8-mile stretch of highway the team is widening is in southeast South Dakota, just west of Canton. The western terminus of the project is Interstate 29. The north-south highway goes from the Canada-North Dakota border to Kansas City, Missouri.
The two-lane U.S. Highway 18 becomes very busy with heavy truck traffic and large equipment during the farming season. The average daily traffic (ADT) for 2018 exceeded 4,500, and over 13 percent of that number includes trucks. The ADT is expected to reach over 12,000 by the year 2050.
The traffic growth is partially attributable to the expected population increase in Canton. Many in the rapidly growing community use U.S. Highway 18 to commute to work in Sioux Falls, South Dakota (about 35 miles north).
"The existing two-lane highway was deteriorating beyond repair and needed to be replaced," said Spencer Thompson, SDDOT Transportation Project Manager.
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Thompson noted that Highway 18, leading further into South Dakota and Iowa, is an important route for hauling corn and grain.
The 8-mile section of the rural highway had a few safety issues, lacking shoulders and having steep in-slopes. Drivers do not have passing opportunities, which poses potential safety risks.
SDDOT and the general contractor, Reede Construction Inc. of Aberdeen, South Dakota, are making multiple changes on U.S. Highway 18 so that the road can handle the greater ADT.
The main element of the project was adding two lanes. The team also replaced the existing concrete on the highway, as it had been overlaid with several lifts of asphalt concrete, and the road needed replacement. They are adding a turnaround for U-turns and for trucking and farming traffic to enter the roadway every half a mile.
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Intersections on U.S. Highway 18 with S.D. Highway 115 and S.D. Highway 11 were greatly expanded with turn lanes and widened radii to allow traffic to enter and exit the areas safely. Lighting is also being installed along Interstate 29, Highway 115, and Highway 11 intersecting with Highway 18. Lighting will improve safety at the intersections.
Upon completing the 8-mile stretch of U.S. Highway 18, it will have two eastbound and two westbound lanes with a raised median.
"We chose a raised median to divide the lanes to save costs on right of way procurement and to limit expansion into landowners' property," Thompson said. "An added feature of a divided highway is safer intersections for entering and exiting traffic due to increased sightlines."
Finally, the team is adding two new box culverts — one on each project end. The new culverts are similar in size to the originals.
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"The existing structures were still effective, but it made sense to remove them since we were already upgrading the road," said Jesse Bruns, Vice President of Estimating and Market Development for Reede Construction. "To cut into the new pavement a few years down the line to replace the box culvert would cost taxpayers more and create increased inconvenience for drivers."
One of the keys to keeping an infrastructure project on schedule is weather. When most of the work occurs outdoors, the schedule is outside of anyone's control and project completion is subject to the elements.
From June 20 through June 22 in 2024, over 18 inches of rain fell on parts of Canton. Government officials described this as a 1,000-year flood, with Canton's approximately 3,000 residents experiencing a rainfall event that had less than a 0.1 percent chance of occurring in any given year, according to the National Weather Service in Sioux Falls.
The gargantuan storm flooded the project site. When the rain came, the team was building the box culvert on the east end of the project. The rains washed out some cords, and some dirt around the box culvert was washed away.
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"We played the waiting game as it took a week to let the ground water drain," Bruns said. "We had to compact [the dirt] again before we could move forward."
The downpours also delayed some paving and grading operations.
Another challenge the team faced was keeping traffic open in both directions while construction was underway.
"The team installed temporary asphalt lanes [that] were constructed to allow traffic flow without adding stoplights and flaggers to help with traffic flow," Thompson said.
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The extra lanes provided space for the team to perform work, move materials through the project zone, and not disturb traffic.
Another remediation was how SDDOT scheduled the project. They broke the project into four different quadrants, dividing each section into two quadrants.
Despite the rains and their impact on the project, the team has progressed the project well. SDDOT has a long working relationship with Reede Construction. The firm has completed numerous sizeable concrete pavement projects for SDDOT.
"They can provide the necessary resources and experience for a project of this size," Thompson said. "They have a concrete paving plant which allows for paving operations to accomplish large quantities of paving per day."
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He also noted that Reede Construction has specialized equipment that enables them to pave both lanes of concrete simultaneously, greatly increasing the production of paving operations.
The piece of equipment mentioned above has a nickname — the double-dumper. The bespoke concrete paving machine is a modified version of an "Iowa Special." The machine is designed to trim the gravel to grade while dumping two trucks and to place dowel bar baskets for the paving.
"The machine allows for a trimmed final grade right before paving for a smoother road and quicker turnaround for paving operations," Thompson said.
Bruns added that the double-dumper enables Reede to increase production. Doing two steps in one makes the process quicker and less expensive.
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Clafin Excavation of Flandreau, South Dakota, is the grading contractor, and this project is one of their first large projects.
"They successfully completed their contracted work in a timely manner for paving to continue," Thompson said.
The project began in July 2023 and is scheduled to be completed in August 2025. The team finished mainline concrete paving in 2024, which kept the project on schedule despite the weather delays.
The key to keeping the project on schedule has been additions to the workforce.
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"Last spring, the whole construction team brought in additional crews at times," Bruns said. "We worked longer hours and worked over weekends in the summer, including some Sundays."
There were also two to three paving crews on the job through the fall of 2024.
As one of the top paving contractors in the state, Reede specializes in these types of large projects. Having them as the general contractor helped move the project along.
The project was let for a tick below $45 million. It is a bit over budget, which Thompson attributes primarily to the historic flooding of 2024.
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"The flood moderately increased some costs,” he said. “However, by working closely with the management team of Reede Construction, the project budget and timelines are being met."
The federal and state governments are funding the project. The former supplied approximately 82 percent of the financing through National Highway Performance Program funds combined with Highway Infrastructure Program Bridge Formula funds. The latter supplied the remaining 18 percent.
When the project is completed later this year, the traveling public along U.S. Highway 18 will experience significantly enhanced safety and efficiency. The additional lanes will reduce conflicts and crashes as well as travel times. Private residences along Highway 18 will have a safer entrance and exit to driveways. The reconstruction of U.S. Highway 18 will transform it into a modern, efficient, and secure transportation corridor for decades.
- Owner: South Dakota Department of Transportation (SDDOT); Ryan Story, Project Engineer
- General Contractor: Reede Construction, Aberdeen, South Dakota
- Designers:Infrastructure Design Group Inc., Sioux Falls, South Dakota; SDDOT
- Other Key Contractors: Clafin Excavation, Flandreau, South Dakota
