South Dakota Will Close Black Hills Tunnels for Inspections

The South Dakota Department of Transportation will inspect several tunnels in the Black Hills from October 5 to 7.

Updated on Sept. 29, 2026 in Car Maintenance

Bold flat-color editorial illustration of a granite mountain tunnel entrance and a paved road, representing infrastructure inspection. — The South Dakota Department of Transportation will close several tunnels in the Black Hills from October 5 to 7 for required structural inspections. AI Illustration. Upload story photo >

Live Poll

Is it worth tolerating temporary road closures to ensure the safety of local transit infrastructure?

The South Dakota Department of Transportation is set to perform its required biannual tunnel inspections throughout the Black Hills region. These inspections will result in temporary road closures and traffic diversions from October 5, 2026, through October 7, 2026.

Why it matters

Routine safety inspections ensure the structural integrity of tunnels along iconic routes like Iron Mountain Road and Needles Highway. By conducting these assessments, the department maintains the safety of motorists traveling through these mountainous areas.

Crews will inspect the Doane Robinson, C.C. Gideon, and Scovel Johnson tunnels, alongside the Hood, Needles Eye, Iron Creek, and Miner's Gateway tunnels. Traffic on Highway 16A will face detours specifically during the Miner's Gateway inspection.

The players

South Dakota Department of Transportation

This state agency oversees the construction, operation, and maintenance of South Dakota's extensive highway and transportation infrastructure.

The details

Road closures are necessary to allow crews to safely evaluate tunnel conditions along Iron Mountain Road and Needles Highway. Authorities have also designated October 8 as a contingency date to account for potential weather delays.

Iron Mountain Road will close for inspections on October 5, 2026.
Needles Highway tunnel inspections and closures occur October 6, 2026.
The Miner's Gateway Tunnel in Keystone will be inspected on October 7, 2026.
October 8, 2026, is reserved for any inspections delayed by weather.

Roadmap

These biannual inspections reflect a broader industry commitment to aging infrastructure preservation within rugged, high-traffic tourism corridors. Such maintenance ensures that scenic roadways remain viable against the challenges of mountain erosion and heavy seasonal visitor volume.

Commuters and tourists should prepare for unavoidable traffic delays and route detours while sections of Highway 16A and other park roads remain closed. Drivers should check local alerts before departing to avoid being caught in the temporary closures.

The takeaway

Drivers planning to navigate the Black Hills during the first week of October should build extra time into their travel itineraries. Monitoring local traffic updates will help travelers navigate around the scheduled closures effectively.