US 191 – Mobridge Slide Repairs logo

Construction Update

Preliminary site preparation, including dirt work and staging (arranging and organizing materials, equipment, and resources needed for the project), has begun. Construction on the embankment is anticipated to begin after the preparation work is complete. Because most of the early work will be off-site, minimal traffic disruption is anticipated.

More updates can be found on the Project Updates page.

Project Overview

The Montana Department of Transportation (MDT) is partnering with M.A. DeAtley Construction, Inc., to reconstruct sections of U.S. Highway 191 (US 191) 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 a section of roadway that was damaged from landslides in the area.

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

Phase 1

The first phase will include work at Site A (see map below), which is the largest landslide area and impacts US 191 between mile markers 84 and 85. This slide has been an issue since the late 1950s but has worsened over the last decade.

Phase 1 construction began in spring 2025 and is anticipated to continue until fall of 2026.

Phase 1 improvements at Site A are detailed below.

Beginning in 2025, crews will:

  • Reconstruct embankments to mitigate landslide movements. This involves adding a toe berm and shear key at the base of the landslide (see visual below).
  • Improve drainage
  • Enhance drainage on Knox Ridge Road

Beginning in 2026, crews will:

  • Improve the grading of the roadway
  • Construct a new roadway surface
  • Upgrade safety features such as new guardrail, signage, and pavement markings
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

The second phase of construction will involve work on two additional landslide locations between mile markers 85 and 86 (Site B), north of the Mobridge Slide (Site A), and near mile marker 89 (Site C), just north of the Missouri River.

Phase 2 construction is anticipated to begin in 2027, depending on completion of design and availability of funding.

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

M.A. DeAtley Construction logo

UPN 9919000