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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.

2.5 miles added
from 2019 - 2021
Next phase begins in 2022
Corridor cost
More than $50 million
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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.

Construction photos from 2019 - 2020

The aerial photo was provided by Barnes Inc.

Photo of construction on US-95 in Culdesac Canyon in 2019 Photo of construction on US-95 in Culdesac Canyon in 2019 Photo of construction on US-95 in Culdesac Canyon in 2019 Aerial photo provided by Barnes Inc. of blasting and drilling efforts on US-95 Culdesac Canyon construction in 2020 Photo of the unpaved future passing lane in Culdesac Canyon Fresh pavement covers the new passing lane on US-95 from MP 279 - 282 The new passing lane from  MP 279 - 282 opened to traffic in late October 2020
Work between mileposts 289 - 290.5
2019 - 2021
Work between mileposts 279 - 282
Work between mileposts 283 - 286
Work between mileposts 296 - 289
Work between mileposts 282 - 283
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


During the summer of 2021, 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.

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US-95 Culdesac Canyon: contact us

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