The Idaho Transportation Department (ITD) is set to begin significant maintenance work Monday on the iconic Rainbow Bridge, which carries State Highway 55 over the North Fork of the Payette River. This effort is aimed at ensuring the bridge continues to meet current safety and capacity standards until a future replacement bridge can be built.

Crews will be repairing reinforced concrete elements, replacing aging expansion joints, and restoring the deck surface — all essential steps to extend the lifespan of the nearly century-old bridge. The maintenance work is expected to wrap up in the fall.

Motorists should be prepared for delays. SH-55 will be reduced to a single lane on weekdays (Mondays at 6 a.m. to Thursdays at 5 p.m.) in the construction area, with temporary traffic signals in place to control traffic flow. Both lanes are expected to reopen on weekends (Fridays through Sundays) and during major holidays this summer to accommodate recreational traffic. However, prior to Memorial Day, travelers should be aware that one lane may still be closed on weekends. Lanes will also be narrowed to 11 feet, requiring oversized vehicles to plan ahead.

Rafters using the North Fork of the Payette River should stay alert when approaching the bridge. ITD advises river users to watch for construction signage and follow the directions of the designated river flagger, especially during periods of overhead work.

“These repairs will help prevent future load restrictions that could impact service vehicles, delivery vehicles, and cattle trucks using SH-55,” ITD said in a project update.

The Rainbow Bridge, with its distinctive concrete arch design, is a well-known landmark in Valley County. Originally constructed in the 1930s, it has long been a vital link connecting Boise-area travelers to McCall, Cascade, and the popular Payette National Forest recreation areas. Each year, tens of thousands of residents and visitors cross the bridge on their way to summer and winter recreation, making it one of the busiest rural highways in the state.

In addition to serving locals, SH-55 is a key commercial route used by freight haulers, agricultural transporters, and delivery services. Any extended restrictions or closures could have ripple effects on regional supply chains. That’s why ITD emphasizes that proactive maintenance is essential to keeping the bridge functional and avoiding emergency repairs or sudden load limits that would force commercial detours.

Local businesses, especially those tied to tourism, are paying close attention to the project. While the temporary lane closures may slow traffic, many business owners prefer planned work over unexpected shutdowns later in the year.

For the latest construction updates, lane closure details, and travel advisories, the public can visit ITD’s official project website or sign up for email alerts.

Originally reported by Sophia Miraglio in Idaho Transportation Department.