US 191 – Mobridge Slide Repairs logo

Project Overview

The Montana Department of Transportation (MDT) and M.A. DeAtley Construction, Inc., are reconstructing sections of U.S. Highway 191 (US 191) in Fergus and Phillips counties near the James Kipp Recreation Area and the Fred Robinson Bridge over the Missouri River. The US 191 – Mobridge Slide Repairs project will help stabilize sections of the highway that have been damaged by landslides.

Landslide sites occur in three different locations along US 191, and repairs at these sites will be completed in two phases.

Phase 1

Phase 1 of the project began in spring 2025 and concluded in fall 2026. This phase included repairs between mile markers 84 and 85 (Site A) and addressed the largest landslide impacting US 191. This slide had been an issue since the late 1950s but had worsened over the last decade.

Phase 1 improvements at Site A included:

  • Reconstructing embankments to mitigate landslide movements, which involved adding a toe berm and shear key at the base of the landslide (see visual)
  • Improving drainage along US 191 and Knox Ridge Road
  • Constructing a new roadway surface
  • mproving the grading of the roadway
  • Upgrading safety features such as new guardrail, signage, and pavement markings

The landslide movement at Site A will continue to slow over the next few years as it builds up resistance against the new toe berm and shear key. Some cracking in the temporary pavement is expected in the short-term as the ground settles. Final paving at this site will be included in Phase 2 of the project after the landslide movement is substantially complete.

A toe berm and shear key will be constructed at the base of a slope to stabilize the area and mitigate further landslides.
A toe berm and shear key will be constructed at the base of a slope to stabilize the area and mitigate further landslides.

Up-to-date road conditions can be found on MDT 511.

Phase 2

Phase 2 of the project is anticipated to begin in 2028, depending on the timeline of the slide settlement, completion of design, and availability of funding. This phase will involve work at Site A and at two additional landslide locations: Site B between mile markers 85 and 86 and Site C near mile marker 89, just north of the Missouri River.

Phase 2 improvements are detailed below.

At Site A, crews will:

  • Complete final site construction (jack-and-bore culvert and final pavement installation)

At Sites A and B, crews will:

  • Reconstruct the soil structures supporting the roadway to prevent further deterioration of the roadway
  • Improve drainage features to reduce infiltration of surface water on the roadway

At Site C, crews will:

  • Widen the roadway
  • Repair the roadway to address bumps and settlements caused by landslide (heaving)

Project Map

US 191 – Mobridge Slide Repairs map
US 191 – Mobridge Slide Repairs map

UPN 9919000