Officials from the South Dakota Department of Transportation recently closed Needles Highway and Iron Mountain Road to inspect the highways’ seven tunnels. According to the Rapid City Journal, engineers and state geologists check the tunnels routinely every two years for any signs of weathering, cracking or loose rock at the requirement of the U.S. Department of Transportation’s Federal Highway Administration.
The tunnels were originally created by dynamite blasts in the 1920s to allow access to the scenic highways of the Black Hills. There is no concern that the tunnels are unsound currently, and teams will continue to check for soft spots and erosion in the coming years.
Read more about transportation in the Black Hills in the Black Hills Knowledge Network news archive.