Idaho Transportation Department photos

The State Highway 16/Interstate 84 interchange

The Idaho Transportation Department will accelerate the construction of multiple interchanges along State Highway 16 in the central Treasure Valley with Leading Idaho funds. The entire corridor is expected to open by 2027, a year earlier than planned.

The new SH-16 corridor will be the area's first new freeway in more than four decades, extending between Interstate 84 and State Highway 44. Access on and off the highway will be limited to interchanges at I-84, Franklin Road, Ustick Road, U.S. Highway 20/26 and SH-44.

"ITD is able to accelerate these interchanges due to a number of factors, including additional funding and efficient management," District Engineer Jason Brinkman said. "We are very proud of the work that has been accomplished, and we are confident this project will improve the mobility for large parts of Ada, Canyon and Gem counties."

With the accelerated schedule, construction will take place in multiple areas along the project. Starting Feb. 10, 2025, work at the US-20/26 interchange will require extended nighttime detours. Traffic on US-20/26 will be detoured from 7 p.m. to 5 a.m. for three weeks to allow crews to safely place 12 steel girders — each weighing 83,000 lbs. — across the roadway for the interchange bridge.

This spring, work will begin to expand the I-84 and SH-16 Interchange and construct a new interchange at Franklin Road. Work on the US-20/26 and Ustick interchanges is already under way, while construction at the SH-44 Interchange is expected to begin by fall 2025.

Contech Engineered Solutions built 57 girders and the retaining wall for the I-84, SH-16 interchange. Contech also is constructing girders for the Simco Road Bridge near Mountain Home and the bridge under SH-55 in the Avimor development.

The first phase was completed in 2014 between US-20/26 and SH-44. The second phase began in 2022 and has included constructing the mainline highway, part of the I-84 Interchange, and many overpasses and local road adjustments.

The final phase of this project was accelerated when additional funding became available through the Idaho Transportation Expansion and Congestion Mitigation (TECM) bonding program. These funds are a deliberate investment to allow ITD to accelerate project timelines to address rapid growth and build critical infrastructure today that would otherwise take many years to build.

The project's planning has taken years, according to boisedev.com, with an environmental impact statement completed by 2011. A first phase, which cost $102 million, extended SH 16 south by 2 miles from State Highway 44 to U.S. 20-26. That work was completed in 2014.

The latest phase of construction started in 2022, with funding for the design costing $25 million, right way acquisitions totaling $86 million and construction costing $253 million, according to boisedev.com. The final phase will cost approximately $276 million.

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