Skip to main content

Interstate 11 Corridor Tier 1 Environmental Impact Statement, Nogales to Wickenburg
Interstate 11 Corridor Tier 1 Environmental Impact Statement, Nogales to Wickenburg

Para traducir este sitio al español, use Google Translate localizado en la parte de abajo.

Current Status

The Interstate-11 (I-11) Draft Tier 1 Environmental Impact Statement and Preliminary Section 4(f) Evaluation (Draft Tier 1 EIS) was completed and made available for public review and comment from April 5, 2019 through July 8, 2019. The study team is considering all comments received on the Draft Tier 1 EIS, conducting additional analysis, and coordinating with stakeholders as needed to prepare a Final Tier 1 EIS, outlining a Preferred Corridor Alternative for I-11, along with the No Build Alternative. All comments and questions received during the Draft Tier 1 EIS comment period will be addressed in the Final Tier 1 EIS, which is expected to be completed and available for review in 2021.

Although the deadline for comments on the Draft Tier 1 EIS document has passed, comments on the Tier 1 EIS Study can be made at any time during the study process. All comments, regardless of when they are submitted, are reviewed and considered by the study team. The Final Tier 1 EIS document will include responses to comments on the Draft Tier 1 EIS document that were received during the April 5, 2019 through July 8, 2019 comment period. To leave a comment related to the Tier 1 EIS Study, visit the Contact Us page.

Zoom in on a satellite view of the corridor alternatives.

Overview video

Study Overview


In December 2015, the U.S. Congress approved the Fixing America’s Surface Transportation (FAST) Act, which is legislation to improve the nation’s surface transportation infrastructure during a five-year period. The FAST Act formally designated I-11 as a proposed transportation route in Arizona. It stated that the I-11 corridor will generally follow State Route 189 and Interstate 19 from Nogales to Tucson, Interstate 10 from Tucson to Phoenix, and US 93 from Wickenburg to the Nevada state line.

The designation doesn’t include funding but identifies I-11 as a high-priority corridor eligible for federal funding. ADOT continues to work with its federal, state and local partners to identify funding for I-11, which, if constructed, is expected to include a combination of new and existing roadways.

Tier 1 EIS Environmental Review Process

ADOT is currently funding and conducting the first step in a tiered environmental study to identify a potential corridor for I-11 between Nogales and Wickenburg. The Tier 1 EIS environmental review process will consider both Build Corridor Alternatives and the No Build (do nothing) Alternative.

Navigating NEPA

For more information on the environmental review process, visit the Environmental Process page.

Tier 1 EIS

The Tier 1 EIS, required by the National Environmental Policy Act, is expected to be complete in 2021. The Feeral Highway Administration will issue a Record of Decision that will present either a Selected Corridor Alternative or the No Build Alternative. If a Build Corridor Alternative is selected, Tier 2 environmental studies would then be required to determine the alignment (the specific route) and design details, such as the width of the median, frontage roads, traffic interchange locations, and other roadway features.

The Difference Between a Corridor and an Alignment For planning purposes, the Build Corridor Alternatives in the Tier 1 EIS are identified as 2,000-foot-wide corridors. The potential I-11 facility (also referred to as an alignment) would generally be 400 feet wide, which includes travel lanes, shoulders, median, and other possible features like frontage roads. The 2,000-foot wide Build Corridor Alternatives for the Tier 1 EIS lay the groundwork for where I-11 could be located. If a Build Corridor Alternative is selected, future studies would be required to determine the specific alignment (or route) of I-11 within the 2,000-foot-wide corridor.
Wickenburg to Nevada

Currently all but 39 miles of the 200-mile drive from Wickenburg to the Nevada state line have been upgraded to a four-lane divided highway to improve traffic flow, support the movement of freight and enhance safety through this heavily traveled area. The entire northern segment of US 93 from Kingman to the Nevada state line (mileposts 1 to 68) is now a four-lane divided highway following the completion of a $71 million project in 2010.

Map illustrates the corridor study area that stretches 280 miles from Nogales to Wickenburg, Arizona. The study area varies in width from approximately 10 wide to 25 miles wile. The map shows the following areas of interest: corridor/study area, cities and towns, county limits, freeway, state/US highways, major streets, railroad tracks, airport, rivers, and lakes. Also shown are the following areas: Bureau of Land Management lands, Reclamation lands, National Forest lands, National Wildlife Refuge, Park and Recreation area, National Park land, National Monument, Tribal Lands, Private Land, State Land, and military area.
Study Map

If you would like to be notified via email when updates are issued, please subscribe for email updates.

Study Purpose and Need

I-11 Purpose and need diagram.

History of the I-11 Corridor

The current ADOT-led Tier 1 EIS builds upon the prior I-11 and Intermountain West Corridor Study (IWCS) completed in 2014, which was a multimodal planning effort that involved ADOT, the Nevada Department of Transportation, Federal Highway Administration, Federal Railroad Administration, Maricopa Association of Governments, Regional Transportation Commission of Southern Nevada, and other key stakeholders.

Upon completion of the IWCS, FHWA and ADOT continued to advance the Tier 1 EIS Study in Arizona for the approximate 280-mile section between Nogales and Wickenburg, as shown on the corridor study area map. The FAST Act formally designates I-11 throughout Arizona, reinforcing ADOT's overall concept for the I-11 Corridor that emerged from the prior IWCS.

For additional information on the IWCS, please visit