Modjeski and Masters is supporting the Idaho Transportation Dept. as prime consultant for a new bridge over the North Fork of the Payette River in Valley County, Idaho.

In addition to designing the bridge, the team will also help determine the future of the existing Rainbow Bridge, which currently carries thousands of vehicles daily. Built in 1933, it was the final link in the new State Highway 55 between Boise and McCall and is listed in the National Register of Historic Places.

The bridge will be built on a new alignment adjacent to the existing bridge, with project partners also including Kimley-Horn, RBCI, NV5, Russo Structures and Anderson Environmental.

The project will be challenging given its location in a narrow canyon that has a significant skew. The team’s most critical considerations include contractor access, minimizing hillside cuts, constructibility and scheduling aspects given seasonal traffic patterns. The preliminary design portion of the project is underway, with construction scheduled for 2028 to 2029.