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Aht’Wy Interchange

An interchange will provide safer access to Aht'Wy Plaza residents and local businesses.

After the structure is built, the Idaho Transportation Department will assume ownership and maintain it as part of the public transportation system.


Knife River Corporation received the bid for the project that will construct an interchange on U.S. Highway 95/U.S. Highway 12 at the east entrance to Aht’Wy Plaza for $24.77 million.

With a contractor now on board, work could begin by mid-May and is expected to take less than two years. The four-lane highway will be separated by concrete barrier and the existing median, turn lanes and acceleration lanes will be eliminated.

Bid Awarded

Aht'Wy Plaza: Interchange Design

The interchange will include a bridge over the highway and four ramps to access the plaza near the east entrance.

The four-lane highway will be separated by concrete barrier, eliminating the existing median, turn lanes and acceleration lanes, to make room for ramps in ITD right of way and avoid environmental impacts. North of the interchange, the grassy median will remain. Retaining walls will be built to support the elevated ramps.

The bridge over US-95 will include a sidewalk and broadband conduit.

The parking area just north of the east entrance will be shifted south to provide the Army Corps of Engineers access to maintain the nearby wetland mitigation site for the Lower Granite Dam (labeled as the goose pasture). The old parking area will be restored with natural vegetation.


View other graphics
Aht'Wy Plaza opens casino with plans to expand
Traffic study conducted to look at how growth would affect drivers
Traffic study identifies need for full interchange upon completion of facility expansion
January 2001
ITD and NPT agree to phased improvements at entrances to handle growth
Fall 2002
Phase one completed with lighting, acceleration lane at east entrance and right turn lanes at both
June 2006
NPTEC passes resolution to pursue interchange instead of the remaining phased improvements
July 2009
NPT hosts public meeting to review alternative designs for interchange
September 2009
Preferred alternative is selected and design continues
NPT works with the Army Corps of Engineer (ACOE) to address concerns over the interchange's design
March 2018
Interchange design adjusted to minimize impacts to ACOE property
Summer 2018
Concrete island constructed at west entrance to restrict left turns from exiting drivers
December 2018
New signs that flash are placed near the entrances, and ITD joins other agencies in emphasis patrol
January 2019
Final design begins, and a road safety audit is conducted
February 2019
Final report from road safety audit delivered
May 2019
Audit improvements made to east entrance
September 2020
Tribe awarded BUILD grant
May 2023
First Construction Phase
September 2023

Plaza access changes on US-95 Aht’Wy Interchange begin September 14

Beginning September 14, 2023 motorists should expect a new traffic pattern affecting access to the Clearwater River Casino & Lodge at the Aht’Wy Interchange project on U.S. Highway 95.

Motorists can anticipate the following traffic pattern changes:

East Entrance: This access point will be closed. A temporary east entrance will be available nearby and closer to the casino. Access to and from the temporary east entrance will be open for both directions of travel on US-95.

West Entrance: Drivers heading southbound on US-95 will not be able to access the plaza at the west entrance. However, this entrance will be accessible for travelers on northbound US-95 to and from the plaza.

May 2023

Interchange in First Construction Phase

The project is in its earliest construction stages. After a well-attended groundbreaking ceremony in April, contractors are getting started and motorists can expect some changes in traffic patterns.

September 2020

$19.1 million grant awarded

In September 2020, the Nez Perce Tribe was awarded a $19.1-million grant to construct the interchange.

May 2019

Adjustment made to right turn lane into east entrance

Work will shift the right turn lane into the east entrance to improve line of sight, per the joint audit's recommendation.

Read more
Road safety audit: final report

February 2019

The road safety audit team provided the final report in February which included a range of options that could be constructed in advance of the planned interchange. Both NPT and ITD are moving forward with options for the east entrance, which include adding an acceleration lane for eastbound traffic and widening the westbound right turn lane to create separation between turning and through traffic.

Work on these interim improvements could begin in spring when weather conditions allow for quality paving and once funding is secured.

January 2019

Road safety audit: initial results

ITD hosted a road safety audit to develop other short-term solutions that could be implemented before construction of the interchange. The audit provided NPT several options to pursue with ITD, which will be further detailed in a final report scheduled to come out in February.

Initial results news story


Plaza access changes on US-95 Aht’Wy Interchange begin September 14.  Read more.

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