ITD Projects Southwest Idaho Idaho 55 Corridor Study

The Draft Idaho 55 Central Corridor Plan is currently undergoing revision. It will also include ITD Research Report 242 titled, “Measures to Alleviate Congestion at Rural Intersections – Case Study: Intersection of State Highway 55, Banks Lowman Road, and Banks-Grade Way.

Comments may be mailed to the Idaho Transportation Department Public Involvement Coordinator at P.O. Box 7129, Boise, ID 83707 or emailed to

Idaho 55 Corridor Study
Project Number: A009(967)
Key Number: 09967

The Idaho Transportation Department (ITD) is studying Idaho 55 to identify current and future needs throughout the corridor. The study will result in a corridor plan that identifies policies and projects important to the development of this major arterial over the next 20 years.

The Idaho 55 highway corridor originates 1.7 miles south of Marsing in Owyhee County at the Idaho/Oregon/Nevada junction with U.S. 95 and serves six counties, ending at the junction of U.S. 95 in New Meadows. Most travelers know the highway for its turns along mountain forests, whitewater rapids and favorite recreation spots. The corridor is an important route that supports the regional daily commute, the long-haul trucking industry and recreational traffic.

Project Description
The completed corridor plan will include an analysis of the existing conditions on the highway; a forecast of future demand over the next 20 years; and a list of short- and long-term improvements on how to modernize transportation on Idaho 55. The document will address the course of the highway as a whole and on a county-by-county basis. The plan will be based on community input, engineering analysis, and city, county and agency planning goals. ITD will include the plan in its Idaho Horizons Long Range Capital Improvement and Preservation Program (LRCIP). LRCIP is a planning document that helps ITD prioritize projects for future years.

The finished corridor plan will include:

  1. Safety: What are the improvements that will make Idaho 55 safer for motorists, pedestrians and residents?
  2. Access Management: How can ITD and local communities manage the effect of development along the corridor so the roadway continues to function safely and efficiently?
  3. Traffic: What are the best ways to improve current traffic flow and capacity throughout the corridor? Can we anticipate future congestion points and develop solutions?
  4. Environment: What are the important environmental issues to consider when ITD builds improvements in the future?

Public Involvement

ITD encourages you to submit comments at any time during the study process. Written comments may be e-mailed to or mailed to: Idaho Transportation Department, P.O. Box 7129 in Boise, ID 83707-1129.


The corridor study began in 2007 and is expected to be completed in 2016.

ITD Office of Communications
(208) 334-8119

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.

Draft Central Corridor Plan Sept. 2015
Idaho 55 Draft Central Corridor Plan
Idaho 55 Draft Central Corridor Plan Appendices
Idaho 55 Comment Sheet

South Corridor Plan Dec. 2013
Idaho 55 South Corridor Plan
Idaho 55 South Corridor Plan Appendices

December 2014 Open House
Display Boards
  1. Welcome
  2. Study Description
  3. Project Funding - Fiscal Year 2014-2018
  4. Ada County Traffic
  5. Ada County High Accident List
  6. Ada County Crashes
  7. Boise County North Traffic
  8. Boise County North High Accident List
  9. Boise County North Crashes
  10. Boise County South Traffic
  11. Boise County South High Accident List
  12. Boise County South Crashes
  13. Needed Improvements for 2025
  14. Needed Improvements for 2035

2008 - 2013 Workshop Materials
View workshop materials
2013 Invitation
2013 Comment Form

Idaho 55, Marsing to Nampa Access Management Plan
View plan