Boulder – Main Street logo

Project Overview

The Montana Department of Transportation (MDT) and its partner Helena Sand & Gravel Inc. are improving about 1 mile of Montana Highway 69 (MT 69), also known as Main Street, through Boulder. Work includes:

  • Replacing the top layer of pavement.
  • Improving drainage at the intersection with Centennial Avenue.
  • Replacing concrete crosswalks with painted asphalt crosswalks.
  • Replacing the landscaped medians with concrete medians.
  • Repairing the Boulder River Bridge.
  • Applying a seal and cover (chip seal).
  • Painting new epoxy pavement markings.
  • Upgrading signage.
  • Improving sidewalk ramps to meet current Americans with Disabilities Act (ADA) guidelines.

Project Location: The project area stretches along Main Street from the Interstate 15 (I-15) northbound ramps to just south of the intersection with Cattle Trail Drive.


No, the road will not be fully closed. Traffic control will be in place, more information will be shared as it becomes available. To stay notified of traffic impacts, subscribe to email or text alerts. Email boulderXYZkljengABCcom or text BOULDER to 844-764-2126*.

Main Street lighting is owned and maintained by the City of Boulder and is not addressed as part of this project. Northwestern Energy is working with the City of Boulder to upgrade these lights to LED.

The City of Boulder cited visibility concerns with snow storage. The Federal Highway Administration (FHWA) agreed with the request and authorized federal funds to replace the landscaped medians with concrete. The blocks from the median landscaping will be provided to the City.

No, MDT does not anticipate this project to impact private property.

Pavement millings may be reused throughout the project. When work is complete, any remaining millings will be offered to MDT Maintenance, the City of Boulder, Jefferson County, or the Contractor (in that order).

Project Area Map

Boulder - Main Street project map Helena Sand and Gravel logo

UPN 9684000