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

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Current Status

The 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. Based on the comments received and any additional technical analysis, the study team will prepare a Final Tier 1 EIS, outlining a Preferred Alternative for I-11. 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 2020.

Although the deadline for comments on the Draft Tier 1 EIS has passed, comments on the study can be made at any time during the study process. To learn more, visit the Contact Us page.

Zoom in on a satellite view of the corridor alternatives.

Overview video

Study Overview

In 2015, the Fixing America’s Surface Transportation Act, or FAST Act, formally designated Interstate 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.

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 Alternative. For planning purposes, the Build Corridor Alternatives in the Tier 1 EIS are identified as 2,000-foot-wide corridors. However if a Build Alternative is selected, the ultimate I-11 facility would be approximately 400 feet wide.

The future I-11 facility would generally be 400 feet wide, which includes travel lanes, shoulders, median, and other possible features like frontage roads. The 2,000-foot wide study corridor for the Tier 1 EIS lays the groundwork for where I-11 would be located. If a Build Alternative is selected, future studies would be required to determine the specific alignment of I-11 within the 2,000-foot-wide corridor.

The Tier 1 Environmental Impact Statement (EIS), required by the National Environmental Policy Act (NEPA), is expected to be complete in 2020. If a Build Corridor Alternative is selected, Tier 2 environmental studies would then be required to determine the alignment and specific design details, such as the width of the median, frontage roads, traffic interchange locations, and other roadway features.

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.

I-11 has been identified as a critical piece of multimodal infrastructure that would support and connect the economies of Arizona and Nevada. It also could be connected to a larger north-south transportation corridor, linking Mexico and Canada. I-11 is intended to provide a high-priority, access-controlled transportation corridor that has the potential to enhance the movement of people and freight, and facilitate regional connectivity, trade, communications and technology in an ever-evolving global marketplace.

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

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Project Purpose and Need

The Purpose and Need Statement is a fundamental part of the NEPA process, providing the basis for identifying, evaluating and screening corridor alternatives. It will be one of the key components in determining and identifying a Selected Corridor Alternative for I-11. The Purpose and Need is based on key transportation-related problems and issues identified in the previous studies and through agency and public input received during the scoping process.

Project Purpose

The purpose of the project is to:

  • Provide a high-priority, access-controlled, north-south transportation corridor
  • Support improved regional mobility for people, goods, and homeland security
  • Connect major metropolitan areas and markets with Mexico and Canada
  • Enhance access to the high-capacity transportation network to support economic vitality

Project Need

The need for this project results from the following issues and opportunities:

  • Population and employment growth
  • Congestion and travel time reliability
  • System linkages and regional interstate mobility
  • Access to economic activity centers
  • Homeland security and national defense

A copy of the Final Purpose and Need report is included on the Documents page.

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 study, FHWA and ADOT continued to advance the I-11 Corridor study in Arizona for the approximate 280-mile section between Nogales and Wickenburg, as shown on the corridor study area map.

For additional information on the previous study, please visit

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 designates I-11 throughout Arizona, reinforcing ADOT’s overall concept for the I-11 Corridor that emerged from the prior IWCS study.