Photo courtesy of the Idaho Transportation Department

A map of the Interstate 15 widening project between the Northgate and Fort Hall interchanges in Idaho.

The Idaho Transportation Department (ITD) began construction to widen Interstate 15 to three lanes in each direction between the Northgate and Fort Hall interchanges to accommodate projected increases in traffic volumes.

The $190 million 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.

The 21-mi. project begins at the Northgate Parkway Interchange (Exit 73) and ends approximately 1 mi. north of the Blackfoot/U.S. 26 Interchange (Exit 93).

Photo courtesy of the Idaho Transportation Department

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. of Boise, Idaho, and Sundt Construction, whose regional office is in Salt Lake City, Utah, are the contractors for the north and south project areas, respectively.

Work will be phased to maintain two lanes of traffic in each direction during the day for most of the project. There will be some nighttime work that requires 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.

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.

Construction is being funded as part of Idaho Gov. Brad Little's Leading Idaho transportation funding initiative. The 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.

Most of I-15 was constructed in the 1960s and 1970s. With the increased population and traffic across eastern Idaho, IDT said it was necessary to modernize aging infrastructure and increase capacity and safety to meet the region's travel demands along the I-15 corridor.

This project is part of a multi-year planning process to improve I-15 between Pocatello and Idaho Falls. Due to the size of the corridor, the planning process is divided into several separate projects.

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