County gets overpass update, opts for concrete roadway

Brookings County commissioners agreed earlier this month to have their section of the road leading up to a new Interstate 29 interchange at 20th Street South/214th Street made out of concrete instead of asphalt.

Brookings City Engineer Jackie Lanning gave a brief overview Aug. 4 on how the design progress is coming along and addressed the direction of the project.

Last year, the County committed $2 million toward the project in conjunction with $2 million from the City and $700,000 via private donors. An $18.7 million BUILD grant that Brookings was awarded last year will cover much of the work.

Lanning said that the project is on schedule and there have not been any delays due to the COVID-19 pandemic. Bidding for the overpass will begin in September 2021, building of the ramps and grading are set for 2022, and the actual paving and bridge construction will be in 2023.

“It’s been moving along on schedule – which is great,” Lanning said. “We had talked to federal highway (officials) earlier in the process about whether COVID would delay any of the deadlines in the BUILD grant, and their response was, ‘No, none of the deadlines are delayed.’ That really made us focus as a team and kept it moving right on schedule.”

Lanning said consultants are working on the preferred alignment of the new roadway, from an environmental standpoint, and it should be ready soon.

“The (Department of Transportation) has done some geotechnical analysis of the area and they have two different pavement types that they’re proposing.”

The commission discussed options of 5.5 inches of asphalt with 12 inches of gravel underneath versus 8 inches of concrete with 5 inches of gravel underneath. Lanning said further research is needed as to whether additional material is needed for construction. 

She said a concrete road has a lifespan of around 40 years, but an asphalt road can last longer with chip-seal and mill and overlay.

Lanning told The Brookings Register the width of pavement on the overpass will be 36 feet and has room for three lanes, but whether there will be three lanes through the entire length of the project is still being decided.

The commissioners chose concrete, since the city is looking at concrete for its portion of the road, and the road will have curb and gutter. If Brookings grows to the east, the county’s portion of the road may also be annexed into the city.

Lanning said there could be a joint bidding process next year for a single contractor to complete the concrete portion of the project.

Lanning said that much of the design process is still underway as officials are working on how to best connect the overpass to 22nd Avenue and 34th Avenue and how turning lanes, driveway exits and storm drains/gutters should function for the overpass.

Lanning said the overpass is evenly split from east to west for the City of Brookings and Brookings County as it crosses over the city-county line. Both the city and county have a half-mile of road to oversee and maintain.

Contact Matthew Rhodes at

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