The Idaho Transportation Department (ITD) is exploring concepts for updating the historic Rainbow Bridge, a 410-foot single-span arch on Highway 55 that stretches across the north fork of the Payette River.
The proposed plan for the bridge, which was built in 1933, includes building a through-arch bridge that would widen the roadway and improve travel conditions for commercial trucks, recreational vehicles and snowplows.
The project is estimated to cost $65 million, according to ITD engineers, who said the project is “on the shelf and ready to go” once approved.
The current timeline shows construction of the new bridge would begin in 2028, ITD said.
The design includes shoulders up to 17-feet-wide curved sections of the roadway to allow for larger, faster moving vehicular traffic that did not exist in the 1930s. According to ITD engineers, trucks weighed roughly 15 tons when the bridge opened in 1933, compared to commercial vehicles today that can weigh up to 100,000 pounds.
ITD said the existing bridge, a well-known landmark from the Art Deco era, must be demolished because the cost of maintaining two bridges would be too high.
Proposed designs have included preserving the look of the bridge railings and artwork that currently adorns the Rainbow Bridge, but public opinion on the project remains split. Some residents support creating a new landmark gateway, while others argue ITD should build a simple, functional replacement.
Photo by Pat NM from Pexels
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