The Idaho Transportation Department (ITD) began construction in late April 2025 on a $28.5 million project to improve safety and capacity on State Highway 75 between Elkhorn Road and River Street.
Construction is expected to be completed in late 2026.
Knife River Corp. — Mountain West is the project contractor.
SH 75 is the primary north-south highway in the Wood River Valley serving the cities of Bellevue, Hailey, Ketchum and Sun Valley in Blaine County. It varies from two to four lanes in the project area.
Improvements include:
• Widening SH 75 to five lanes between Elkhorn Road and Serenade Lane.
• Widening SH 75 to three lanes with 10-ft. bike lanes and sidewalks between Serenade Lane and River Street.
• Widening the Trail Creek Bridge to three lanes with bike lanes and sidewalks.
• Upgrading the traffic signal at the SH 75/Elkhorn Road intersection.
• Installing a traffic signal at the SH 75/Serenade Lane intersection.
• Improving some local roads, including Serenade Lane and Elkhorn Road.
• Undergrounding power lines.
These changes have been developed to accommodate traffic projections for the next 20 years.
Crews began removing trees in select locations the week of April 28.
During construction, the speed limit will be reduced to 25 mph in the construction zone, with one lane remaining open in each direction between Elkhorn Road and River Street. Closures will occur on local roads, and detours will be in place. Traffic shifts will occur on SH 75 and local roads.
Work is slated for Monday-Saturday between 7:30 a.m.–7 p.m. with the occasional exception on nights and weekends.
ITD spokesperson Courtney Wagner told mtexpress.com that crews were starting in the northbound lanes of SH 75 between Elkhorn Road and Serenade Lane.
She said the project was split into two years because of funding, as well as weather constraints.
"It is pretty standard for us to split costs between two years especially if the construction is going to take that two years anyway," she wrote to the mtexpress.com. "Our planner looks at seven years out, so it was the efficient way to get the funding for the construction while allowing more in the budget for other projects to start as well."
