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US-12: Saddle Camp to Post Office Creek

Widening four miles of US-12 will increase safety on this narrow, winding route.

Shoulders of the highway will be widened to two feet.

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Design details

Shoulders will be widened to two feet, requiring the use of gabion baskets to form retaining walls along the edge of the river. Guardrail, signage and drainage culverts will be replaced.

Access to Weir Hot Springs will be improved, and the parking area will be paved.

The travel lanes of the highway will be repaved in a larger project scheduled for 2023.

Environmental process

ITD is evaluating the effect of proposed changes on wetlands, wildlife, archaeological sites and more. Given the highway’s designation as a scenic byway along a Wild and Scenic River, ITD has been working closely with the U.S. Forest Service.

Proposed improvements will be designed to blend in with the natural scenery. For example, road signs will be painted brown on the back, and new retaining walls will be covered with vegetation so that they will not be visible to river users.

Tribal study

A study has been underway since 2019 to catalog and identify any areas that may be of cultural concern to the Nez Perce Tribe.

Once the study is complete, ITD will work with the tribe to avoid any areas and to mitigate any adverse effects if necessary. This process must be complete before ITD can finish the environmental process and obtain any land or easements needed to widen the highway.

Corridor plans

ITD plans to widen the shoulders of US-12 from Syringa area to Warm Springs (60 miles). Most projects are in design, and all are dependent on the completion of the study with the Nez Perce Tribe.

Widening projects currently in design besides this project include ten miles in 2023 between the Lochsa Ranger Station and Holly Creek and another eight miles in 2028 from Tumble Creek to the Lochsa Ranger Station. For a complete list of projects, visit

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