Roadwork starts on Idaho’s historic Rainbow Bridge linking Boise, McCall
Motorists traveling between Boise and McCall along Idaho 55 should plan extra time for their trip starting next week as road crews begin maintenance work on the historic Rainbow Bridge just north of Smiths Ferry in Valley County.
Lane closures and temporary traffic signals will be in place each week, from 6 a.m. to 5 p.m. Monday through Thursday, the Idaho Transportation Department said Friday in news release. No impacts are expected for higher-use travel days Friday to Sunday, though the two-lane bridge might be down to one lane on weekends this month ahead of Memorial Day on May 26, the agency said.
Work on the bridge starting Monday includes repairing the deck surface, reinforcing concrete bridge elements and replacing bridge expansion joints, according to a construction update website. The project is intended to ensure the aging bridge meets current safety and capacity requirements, ITD said.
During maintenance of the landmark span built in 1933, lanes will be reduced to widths of 11 feet before it wraps up by the fall, ITD said. However, traffic is expected to flow normally on all major holidays this summer, including Memorial Day, Fourth of July and Labor Day.
The months-long road project is unrelated to plans to permanently replace the 92-year-old arched bridge, which is listed in the National Register of Historic Places. Last summer, ITD completed initial exploratory work, including drilling for rock and core samples around the existing bridge.
A decision has yet to be made about whether to preserve the current span over the North Fork of the Payette River, ITD spokesperson Sophia Miraglio said in an email to the Idaho Statesman. Final design plans for a new bridge are expected to be ready in fall 2026, she said. Construction is expected to start in 2028 or 2029, ITD said.
The estimated price tag to replace the bridge is $60 million, Miraglio said. That total will cover design, as well as construction of the bridge, roadway and retaining wall.
“The final cost of this project will depend on several factors such as the exact location and design of the bridge, and the extent of roadway work that is necessary,” she said.
The bridge maintenance work starting Monday could affect summer rafting on the Payette River. Flaggers will direct river users on the upstream side during overhead bridge work, ITD said. Signs warning of construction ahead will be placed upstream of the bridge, the boat launch area at Cabarton Road Bridge and downstream raft take outs in Smiths Ferry.
