Multiyear construction begins next week to widen I-15 between the Northgate and Fort Hall interchanges

Posted on by Justin Smith
Photograph of I-15 and the Northgate Interchange

The Idaho Transportation Department (ITD) is beginning construction to widen Interstate 15 (I-15) to three lanes in each direction between the Northgate and Fort Hall interchanges to accommodate projected increases in traffic volumes. This Leading Idaho multi-year project includes widening I-15, constructing a median barrier to separate opposing lanes of traffic and reconstructing bridge structures, including overpasses and underpasses, to accommodate the additional lanes.

Motorists can expect to see traffic control devices in the project area as early as Monday morning. Work has been phased to maintain two lanes of traffic in each direction during the day for most of the project. However, motorists should be aware some nighttime work will require single-lane closures.

This fall, crews will shift traffic to create the space they need to build a median wall, reconstruct structures, and demolish and reconstruct the existing northbound lanes of the interstate.

During construction, motorists should expect:

  • Nighttime work begins the week of August 19 and will continue for the first couple weeks of construction. Work will occur from 7 p.m. to 6 a.m. Nighttime single-lane closures may happen occasionally after this period.
  • Daytime work is expected to begin early this fall and will occur between the hours of 7 a.m. and 6 p.m.
  • Lane restrictions will occur on I-15. Most work requiring lane restrictions is anticipated to occur at night.
  • Ramp adjustments will occur at the Fort Hall Interchange (Exit 80) to match the grade of the new mainline.
  • Variable speed limit signs will be installed in the project area, allowing ITD to lower speeds when crews are working near traffic.

Construction is anticipated to be completed in 2027. The project will increase capacity and improve safety on I-15 to serve East Idaho’s growing transportation volumes for years to come.

Due to the large project area, the widening of this stretch of I-15 has been divided into two projects with separate contractors. These contractors will work simultaneously to complete the projects. Western Construction, Inc. and Sundt Construction are the contractors for the north and south project areas, respectively.

Construction is being funded as part of Idaho Governor Brad Little’s Leading Idaho transportation funding initiative. The Leading Idaho initiative allows ITD to take a deliberate approach to advance large projects that will enhance safety, improve mobility, further strengthen Idaho’s economy, and positively impact communities across the state for years to come.

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