Idaho's continued investment in its Interstate 15 corridor is bringing capacity and safety improvements to one of southeast Idaho's key transportation routes. Sundt is working with the Idaho Transportation Department on highway reconstruction and widening projects intended to accommodate growing traffic while improving movement for freight and regional travelers.
The I-86 and I-15 system interchange in Pocatello, known as the Flying Y, underwent a major reconstruction to address aging infrastructure and increased traffic volumes. The interchange was originally built in the 1960s.
The work included eight new bridges, 10 retaining walls, new and modified ramps, highway realignments and extensive earthwork. Sundt and its project partners also incorporated changes to construction phasing that allowed more excavated material to be reused onsite.
According to Sundt, the approach reduced imported earthwork by approximately 200,000 cubic yards and lowered the amount of material exported or treated as waste by about 350,000 cubic yards.
The Flying Y project was completed in fall 2025.
Sundt is also working on the I-15 widening program between the Northgate and Fort Hall interchanges. The project is expanding the interstate to three lanes in each direction while replacing and improving bridges, interchange infrastructure and other transportation elements.
The project team has used slip-form construction for the concrete median barrier, allowing continuous placement instead of conventional hand-forming. Sundt said the approach, combined with changes to the construction sequence, shortened the original schedule by six months.
The broader I-15 program addresses aging infrastructure along a heavily traveled corridor in eastern Idaho. ITD began construction between Northgate and Fort Hall in 2024, with completion currently expected in 2027.
Traffic has already been shifted onto newly constructed lanes as crews continue work on the remaining portions of the interstate. ITD reported that the completed configuration will provide three lanes in each direction between Northgate and Fort Hall.
The projects demonstrate the scale of transportation investment required to modernize aging interstate infrastructure while maintaining traffic through active construction zones. For highway contractors and public-sector owners, the work also highlights how construction phasing, material reuse and specialized concrete placement can affect project schedules and material requirements.
The I-15 improvements are designed to increase capacity and safety along a corridor serving regional traffic, commercial vehicles and communities throughout southeast Idaho.
Source: Sundt.
