SH-55 Rainbow Bridge

Nearly a century after its construction, the current Rainbow Bridge no longer meets ITD standards for state highway bridges. Despite regular maintenance and major repairs, the structure is deteriorating to the point where ITD will no longer be able to maintain it for highway traffic. Other issues include narrow lane and shoulder widths, tight curves on both sides of the bridge, and limited sight distance for drivers.

In 2021, ITD completed an early feasibility study to evaluate the scope and potential issues for building a new bridge adjacent to the existing bridge.

Starting in 2024, ITD will work with technical and environmental experts, agencies, and community members to design a new bridge. This process will include: 

• Completing environmental studies regarding wetlands, endangered species, cultural resources, viewshed and socioeconomic resources, the Clean Water Act, and other issues.
• Completing technical studies such as geotechnical and hydraulics work.
• Evaluating a range of alternatives for a new bridge.
• Determining the future of the existing bridge.
• Developing design and construction plans for the bridge and roadway.
• Working with local agencies and the public throughout the process.

This project is funded to start construction in 2028. 

ITD will approach decisions about the Rainbow Bridge with a high level of transparency, education and community involvement. The community input process will be a key component of the final recommendation for the new bridge and the existing bridge. 

ITD will host a series of community open houses and small-group meetings during this project: 

• Community open houses will be scheduled at key points of the design process. The first set was held in 2024 on July 23 in McCall, July 25 in Horseshoe Bend and online July 23 – Aug. 9.
• A Bridge Involvement Group will meet one week prior to each community open house. The first meeting as held July 2024 in Cascade. Meetings are open to any community members who are willing to invest a higher level of time and engagement. 

The project began in 2021 with construction set to start in 2028.