Idaho US-12 Rock Scaling Project Near Arrow Bridge to Cause Delays and Possible Closures

Motorists travelling along U.S. Highway 12 near the Arrow Bridge in north‑central Idaho should prepare for delays and potential full closures as the Idaho Transportation Department (ITD) undertakes an emergency rock‑scaling project. In a press release dated Nov. 19, 2025, ITD announced that specialized crews have mobilized to stabilize steep slopes above the highway after engineers observed loose rock and other debris threatening to fall onto the roadway. The project area is in a narrow canyon along the Clearwater River at milepost 28, about 4 miles east of Arrow Junction, where the highway has previously experienced rockslides.

ITD explained that the first phase of the project involves hand‑scaling the hillside and installing anchor points so that workers can rappel safely down the slopes. Once anchors are in place, crews will use pry bars and hydraulic tools to dislodge loose rocks. Flaggers will halt traffic in both directions for up to 20 minutes at a time while debris is removed so that workers are not exposed to passing vehicles. The department cautioned that a complete closure could be necessary if scaling reveals an especially large or unstable block of rock. If that happens, the highway may remain closed until protective mesh can be secured over the slope to prevent additional slides【475694874646096†L25-L43】.

Rock removal is expected to begin Friday, Nov. 21, and continue through at least the following week. Drivers should expect delays and are encouraged to check 511.idaho.gov for current conditions and closure updates. Motorists approaching from the west may be stopped near Arrow Junction, while those coming from the east could be held near the Spalding Bridge. ITD warns that cell service in the canyon is limited, so travelers should plan ahead and carry emergency supplies.

U.S. 12 is a vital freight and tourism corridor connecting the Lewiston‑Clarkston valley to communities along the Clearwater and Lochsa rivers. The agency says proactive removal of loose rock will reduce the risk of future landslides that could close the highway for days or weeks. Once scaling is complete, crews will install high‑strength wire mesh and rock bolts to reinforce the slope. "We appreciate the public’s patience as we address this safety issue," an ITD spokesperson said. "Our goal is to get the work done as quickly and safely as possible so drivers can continue using this important route." Travelers are urged to obey flaggers, watch for equipment and allow extra time during the emergency project.