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US-12 and 21st Street

This project will realign the busiest intersection in Central Idaho to improve safety and traffic flow.

After construction, the design will resemble that of standard intersections and be made of concrete, which resists wear from heavier traffic better than traditional pavement.

Construction phases
Impacts will be consistent.
See the local detour.
Planned improvements
Preview changes.
Project updates
Completed traffic study
Asset 5
Winter 2016
Gathered public comments
Asset 5
Spring 2017
Completed preliminary design
Asset 5
Fall 2017
Finalized design
Asset 5
March 2019
Anticipated beginning of construction
Asset 5
October 2019
Anticipated end of construction
Asset 5

Downloads & Resources

HandoutsAsset 4
Asset 5
April 4

Detours start

Detours planned to be in place Monday, April 8.

April 4 update
Asset 5
March 2019

Nighttime work begins

Utility work is ongoing, nighttime work is expected to start April 1, and daytime work will follow soon after that. Once daytime work starts, detours will be in place.

March 2019 update
Asset 5
February 2019

Public meeting

Construction is anticipated to begin in March, with an open house held in late February for the public to ask questions.



Detours are in place and will be for the next five months. Truck traffic traveling on 21st Street is advised to use 11th Avenue and 18th Street rather than the detour from Idaho Street to 21st Street to avoid a sharp curve.

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