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US-95: Culdesac Canyon Passing Lane

Phased construction in the canyon will add an 11-mile passing lane from Winchester to Culdesac to provide southbound drivers safer opportunities to pass.

Blasting begins May 2022
Fact sheet
Corridor cost
More than $50 million
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2022 construction

Work began in March 2022 to build the next 2.3 miles of a new passing lane for southbound drivers.

Construction began with tree removal on both sides of the highway. Blasting will start in May and be concentrated in the spring to make room for the extra lane. Blasts will be timed to avoid peak hours and will typically require a one-hour closure. Pay attention to signs in the work zone to learn about the timing of the next blast or check

In this phase, crews will also replace the culvert for Rock Creek. For most of construction, drivers can expect all existing lanes to remain open. The contractor may reduce the highway to one lane at night.

More on construction

Corridor plans

The Idaho Transportation Department is in the process of adding a passing lane for southbound drivers on Winchester Hill through the canyon. Work started in 2016 and will take several years to complete.

  • Phase 1 was completed in 2016 from mileposts 289 – 290.5
  • Phase 2 was built in 2019 to 2020 from mileposts 279 – 282
  • Phases 3 will be constructed in 2022 from mileposts 283 – 286
  • Phase 4 will be constructed in 2024 from mileposts 286 – 289
  • Phase 5 will connect earlier phases in 2026 from milepost 282 – 283

Construction costs are expected to be more than $50 million. Once completed, the passing lane will be 11 miles long. Culverts and other structures will be upgraded to be more fish-friendly as well.

Work between mileposts 289 - 290.5
2019 - 2020
Work between mileposts 279 - 282
Work between mileposts 283 - 286
Work between mileposts 286 - 289
Work between mileposts 282 - 283
March 2022

Third phase begins

Work begins March 2022 to start the third phase of construction in this corridor.

Read more
Summer 2021

Fiber installation

Crews installed 2.5 miles of fiber conduit along the previously opened passing lane to allow providers to eventually offer high-speed internet to some of the most rural areas of Idaho. Nearly 12 miles of repaving was also completed nearby.

Read more
October 2020

New passing lane opens

As of late October 2020, traffic impacts ceased on US-95, and the new passing lane (2.5 miles) was opened for southbound drivers.

March 2020

Blasting begins again

Blasting is scheduled to avoid peak commute times or weekends and is expected to last for an hour at a time.

Blasting schedule

Season 1 ends

About 1.5 miles of new passing lane was completed but not paved.

Season 1 summary
April 2019

Daytime blasting

Although most complete closures of US-95 will be scheduled at night, during the second week of April, traffic will be stopped in both directions to allow the construction of an equipment access trail above the rock slope. Rock and other debris will be pushed off the slope into a catchment area for cleanup. Drivers should expect delays of at least 15 minutes; if rock falls onto the road, delays could become longer as crews remove it.

March 2019

Signage and guardrail work begins

Expect reduced speeds now that contractors are on scene to replace signage and guardrail.

Construction overview


Blasting begins in May, with the first scheduled for May 10. Read more.

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US-95 Culdesac Canyon: contact us

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