Speed Limits to Vary Between Flandreau and Brookings on I-29

Watch out for Sheriff Rosco clicking his remote control north of Flandreau. The Department of Transportation is putting up variable speed limit signs between the Flandreau and Brookings exits on Interstate 29:

These speed limit signs will change in real time based on weather and road conditions to keep drivers safe this winter.

Several states, such as Colorado and Wyoming, already utilize these signs, and South Dakota is following suit.

I-29 often experiences crashes and injuries from extreme winter weather. The Department of Transportation plans on adding it on I-90 between Sturgis and Tilford next year as well.

“You look at in the Big Sioux River area in Brookings, there’s been a higher rate of winter crashes,” said Craig Smith, the Director of Operations for SD DOT. “Trying to identify that using some of the past history to identify those locations was used” [Fiona Sullivan, “Variable Speed Limits Being Installed Between Brookings and Flandreau,” KSFY-TV, 2025.10.10].

A map in the DOT project overview shows that from 2018 through 2022, 55% of crashes along that 20-mile corridor of chaos resulted from overdriving bad weather conditions:

In an April 2024 public meeting in Brookings on the project, DOT said the ten states (including comparably snowy and desolate Colorado and Wyoming!) that had deployed variable speed limits saw crashes decline up to 34%, fatal or injury crashes by 51%, and rear-end crashes by 65%. Even for those of you who are convinced your Bo and Luke skills will keep you from ever getting into a wreck, DOT says variable speed limits can reduce Interstate closures by 33%. And DOT assures us that the cameras, sensors, and blinky signs are not Sheriff Rosco or Big Brother:

So keep an eye on those changing speed limits between Brookings and Flandreau, and drive more carefully!

Related Reading (not while you are driving, please!):

• SDDOT copies its crash and benefit/cost ratio figures from the Federal Highway Administration, which pulls much of its data from this detailed May 2021 paper.
• FHA summarizes weather criteria some other states use to determine their variable speed limits.
• Texas A&M Transportation Institute says variable speed limits made for a “calmer driving experience” in the United Kingdom and decreased travel times in Germany.