Montana Department of Transportation

Public Involvement

S-472 Blue Slide Road Repair
Sanders County

Construction Update

Conditions are safe for motorists to travel on both lanes in the recently damaged area.

  • Two lanes are open with no restrictions.
  • Motorists will drive on gravel surface.
  • Speed limit is reduced.

Next Steps

Construction of the long-term improvements is anticipated to begin in September and be completed this fall.

Construction includes:

  • Installing a larger culvert.
  • Removing uphill rocks that are falling hazards.
  • Improving roadside drainages.
  • Replacing rail barriers.
  • Repaving the roadway.

What to expect during construction:

  • Construction is anticipated to take 4–6 weeks to complete.
  • Short-term road closures will be necessary to install the new culvert and remove uphill rocks.
  • One lane will remain open during construction.
  • Traffic will be controlled by a stop light or flaggers.
  • Motorists will travel on gravel at reduced speeds.

Project Overview

Blue Slide Road Project image

The Montana Department of Transportation is reconstructing a section of Blue Slide Road nine miles west of Thompson Falls that was severely damaged in April 2018.

Heavy spring snowmelt combined with heavy rain caused Cougar Creek to overflow and wash out the gravel beneath the pavement on Blue Slide Road.

Reconstruction of the roadway is occurring in two phases.

PHASE 1 | Short-term fix to stabilize and open the roadway to traffic.
May — June 2018

  • Work will be conducted during the day between 7 a.m. and 7 p.m.
  • Traffic will be controlled with stop lights and/or flaggers.
  • Some full closures and detours may be necessary.
  • MDT will notify the community in advance of closures and detours.
  • Once open, motorists will drive on gravel surface and speed limit will be reduced.

PHASE 2 | Long-term fix to prevent future damage.
July — Fall 2018

  • Complete full evaluation and identify issues that caused the damage.
  • Conduct environmental evaluation and hydraulic analysis.
  • Finish rock fall mitigation evaluation.
  • Host public open house to share Phase 2 construction plans.
  • Construction complete in Fall 2018.

Sign Up For Construction Email Notifications

TEXT: BLUESLIDE TO 22828 | CALL: 406-465-3350 | EMAIL: