ITD outlines summer work on Highway 55, Rainbow Bridge replacement and intersection upgrades

The Idaho Transportation Department (ITD) told Valley County commissioners on May 12 it plans sealcoating, bridge replacements and phased improvements on Highway 55 this summer, and has a multi‑year corridor study in the pipeline to guide longer-term upgrades.

Jason Brinkman, district engineer for Southwest Idaho and division administrator at ITD, said the department plans a sealcoat project from the south city limits of Horseshoe Bend north to about mile marker 91—just north of Banks and near the Forest Service boundary—with a projected start in July. "That, of course, will have some single lane closures and will consist of daytime work Monday through Thursday and half a day Friday at noon," Brinkman said. He added crews expect most northbound and southbound traffic to be open outside of brief closures.

Brinkman described two culvert/bridge replacements tied to the sealcoat corridor: a larger bridge replacing a deep buried box culvert near Fleming Creek and a near‑twin project at Goose Creek. He said the Fleming Creek work has experienced delays and now looks likely to finish in the fall.

ITD also reported short, intermittent closures this summer for maintenance on the Rainbow Bridge, including brief stoppages of up to about 15 minutes when a crane crosses the roadway. "There will be an occasional blockage or short term closure of the highway for 15 minutes or so," Brinkman said, adding that a separate Rainbow Bridge replacement project is in design and will be located a few hundred feet upstream; public meetings on that replacement are planned this summer.

On the Banks‑Lomond intersection, Brinkman said ITD activated a new traffic signal and installed remote monitoring to collect continuous traffic counts and camera data. He described the signal as operating in fully actuated mode at low volumes with timing plans for heavier periods. "We don't yet have the notion of doing anything adaptive there ... but it is an opportunity to do that in the future if those conditions warrant," he said. ITD staff said they will monitor queue lengths and add temporary signage on the busiest weekends (typically late June through Labor Day) and may deploy a portable message trailer north of the passing lanes to warn southbound drivers.

Brinkman said an enhancement project in design would ultimately widen bridges at the intersection to add turning lanes and allow more efficient signal timing; that project is on ITD's program with an approximate five‑year timeframe. He described short‑term fixes to keep the current one‑lane bridges operating safely, including dual detection systems to prevent opposing traffic entering the narrow bridge at the same time.

ITD noted other planned or ongoing work across the district: shoulder work and guardrail installation around Round Valley associated with a new changeable message sign (DMS), spot paving and maintenance between Horseshoe Bend and mile marker 91, and a Little Goose bridge project toward New Meadows expected to resume in early June with portable traffic signals and single‑lane operations. Brinkman said some tree removal work is scheduled in fiscal year 2028, and crews continue annual selective removals and spot cleanup after storms.

Commissioners pressed ITD on large‑truck impacts and pavement grooving on corridors seeing heavy truck traffic. Brinkman acknowledged freight pressures on both Highway 55 and U.S. 95, and recounted a temporary rule change that allowed longer service vehicles on Highway 55 during a 37‑day U.S. 95 landslide closure. He said the permanent geometry and bridge replacements will affect whether a full legal 53‑foot trailer can be accommodated on some segments; the Rainbow Bridge replacement is expected to eliminate the last restrictive geometry at that crossing.

Brinkman said a corridor or "quarter" study will be released for solicitation for a design consultant soon; he noted ITD had won a roughly $4,000,000 grant to study needs in the McCall area (both the existing route through town and parallel routes) and to identify needed intersection and corridor improvements, right‑of‑way needs and mitigations.

Commissioners asked about sight‑distance improvements, rockfall and debris risks, prioritization of turn lanes, and outreach to private landowners where hazardous trees lie outside the state right‑of‑way. Brinkman said ITD will continue to partner with the county to notify landowners and may assist with removal if trees fall into the right‑of‑way.

Why it matters: Valley County residents and businesses rely on Highway 55 and U.S. 95 for regional travel and freight. Near‑term maintenance and lane closures will affect summer travel; the corridor study and bridge replacements will shape whether future traffic, including larger freight trailers, can be accommodated safely.

Commissioners asked ITD to return for more detailed briefings as the corridor study and Rainbow Bridge project advance; ITD said more public meetings will be scheduled this summer.