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

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Study Overview

In March 2016, the Federal Highway Administration (FHWA) and the Arizona Department of Transportation (ADOT) initiated the environmental review process for a portion of the Interstate 11 (I-11) Corridor, specifically from Nogales to Wickenburg, Arizona. An Alternatives Selection Report (ASR) and Tier 1 Environmental Impact Statement (EIS) will be prepared as part of this process in accordance with the National Environmental Policy Act (NEPA) and other regulatory requirements.

This effort builds upon the prior I-11 and Intermountain West Corridor Study (IWCS) completed in 2014, which was a multimodal planning effort led by ADOT and the Nevada Department of Transportation (NDOT), in partnership with FHWA, Federal Railroad Administration (FRA), Maricopa Association of Governments (MAG), Regional Transportation Commission of Southern Nevada (RTC), and other key stakeholders.

The IWCS broadly defined the I-11 corridor from Arizona’s border with Mexico through northern Nevada. In December 2015, the US Congress approved the Fixing America’s Surface Transportation (FAST) Act, a five-year legislation to improve the nation’s surface transportation infrastructure, which formally designates I-11 throughout both states. Subsequent planning efforts, such as this Tier 1 EIS, will continue to advance corridor planning.

For additional information on the previous study, please visit

I-11 is a critical piece of multimodal infrastructure that will 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. The purpose of I-11 is to provide a high-priority, access-controlled transportation corridor that has the potential to enhance movement of people and freight, facilitate regional connectivity, trade, communications and technology.

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 selecting a Preferred Corridor Alternative for I-11. The Purpose and Need is based on key transportation-related problems and issues identified in the previous I-11 IWCS and through agency and public input received during the scoping process.

The number of corridor alternatives will then be reduced and carried forward in the Draft Tier 1 EIS document. The Draft Tier 1 EIS document will continue to assess in further detail the potential social, economic, and natural environmental impacts of the No-Build Alternative (the do-nothing option) and a reasonable range of corridor alternatives, including a phased implementation plan. A phased implementation plan includes smaller segments of a corridor alternative that may advance as separate, independent projects following completion of the Tier 1 EIS process. The Draft Tier 1 EIS document also will identify a Preferred Alternative (expected to be 2000’ wide). If a build alternative is identified, then FHWA will issue a combined final decision document known as a Final Tier 1 EIS and Record of Decision, which will identify the Selected Corridor Alternative.

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.

In December 2015, the US Congress approved the Fixing America’s Surface Transportation (FAST) Act, which is a 5-year legislation to improve the Nation’s surface transportation infrastructure. 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.

History of the I-11 Corridor

This ADOT-led study 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, FHWA, 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 are continuing 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: