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ITD Projects GARVEE D3 I84 Caldwell to Meridian Project Corridor I84 Karcher Interchange to Five Mile Environmental Study

I-84, Karcher Interchange to Five Mile Environmental Study

Project Facts

Project Number: A010(002)
Key Number: 10002
Mileposts 33.0 to 49.0

Most of the Treasure Valley was rural when I-84 was first built in the late 1960s. Population growth and development since then are causing a rapid shift from a rural to suburban setting.

The Idaho Transportation Department (ITD) conducted the I-84, Karcher Interchange to Five Mile Environmental Study through the GARVEE Transportation Program. The study identifies long-term improvements to I-84 from the Karcher Interchange in Nampa to the Five Mile Overpass in Boise. The completed study identifies the final buildout for I-84.


An environmental document was prepared for the Karcher Interchange to Five Mile Road segment in accordance with the National Environmental Policy Act (NEPA). The Federal Highway Administration issued a Finding of No Significant Impact (FONSI) in April 2009.

The comprehensive study allowed ITD to develop possible alternatives for highway improvements. Several scientific studies including a noise and air quality analysis, along with traffic, structure and geotechnical studies were conducted. The environmental document also includes:

  • A long-term improvement plan that defines a comprehensive package of recommendations for managing and improving the transportation system in the study area.

  • A conceptual plan that identifies design options for the interstate mainline and existing interchange.

  • Environmental documentation that identifies the impacts the proposed improvements may have to the human and natural environment.

  • The preferred alternative that was selected based on a comprehensive evaluation of environmental impacts, cost, engineering aspects and public opinion.

  • Right-of-way requirements for additional property near the project that will need to be purchased for future construction.

  • The study included a collaborative involvement process with the public, local jurisdictions and property owners to determine the best options for improvement. Public meetings were held throughout the study process.

The I-84 Corridor Study, completed by the Community Planning Association of Southwest Idaho (COMPASS) and ITD in 2001, identified long-term needs for the interstate. This environmental study relied heavily on the recommendations of the 2001 study and finalized the planning and design process for this section of the interstate corridor.

The Communities in Motion: Regional Long-Range Transportation Plan for Southwest Idaho, adopted by the COMPASS Board in 2006, recommended maintaining and/or rebuilding existing interchanges to accommodate widening the interstate. It also recommended conducting a corridor-level alternatives analysis that would examine improvements such as High Occupancy Vehicle lanes, ramp metering and improvements to bus


The I-84, Karcher Interchange to Five Mile Environmental Study was funded with GARVEE bonds. ITD began the study in January 2007, and environmental clearance was gained through a finding of no significant impact (FONSI) in April 2009.

Compliance with Title VI of the Civil Rights Act

The Idaho Transportation Department (ITD) is committed to compliance with Title VI of the Civil Rights Act of 1964 and all related regulations and directives. ITD assures that no person shall on the grounds of race, color, national origin, gender, age, or disability be excluded from participation in, be denied the benefits of, or be otherwise subjected to discrimination under any ITD service, program, or activity. The department also assures that every effort will be made to prevent discrimination through the impacts of its programs, policies, and activities on minority and low-income populations. In addition, the department will take reasonable steps to provide meaningful access to services for persons with Limited English Proficiency.

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P.O. Box 7129 • Boise, ID 83707-1129
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Environmental Assessment (EA)

Please click on the link below to download a .zip file of the project materials.

I-84 Karcher Interchange to Five Mile Environmental Study

ITD Public Involvement
P.O. Box 7129
Boise, ID 83707-1129
Phone: (208) 334-8119
Fax: (208) 334-8563
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(800) 377-3529 to use Idaho Relay System

Page Last Modified: 11/10/2014 2:50:21 PM

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Idaho Transportation Department
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