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

April 14, 2017

 Why I-11?

The concept of a high-capacity transportation facility connecting Canada and Mexico through the western U.S. has been considered for more than 20 years. It was initially identified as the CANAMEX Trade Corridor, which was outlined in the 1991 Intermodal Surface Transportation Efficiency Act, established under the North American Free Trade Agreement in 1993, and defined by Congress in the 1995 National Highway Systems Designation Act. In 2014, the Arizona Department of Transportation and the Nevada Department of Transportation jointly completed the I-11 and Intermountain West Corridor Study, with the purpose of determining whether sufficient justification exists for a new high-capacity, multimodal transportation corridor, and if so, to establish the likely potential routes.

The Federal Highway Administration and the Arizona Department of Transportation continue to study the I-11 Corridor in Arizona through preparation of the I-11 Tier 1 Environmental Impact Statement. An early step in preparing an EIS is to determine if transportation challenges or other needs exist in a defined study area – in this case, within the approximate 280-mile corridor between Nogales and Wickenburg. If the analysis demonstrates a clear Purpose and Need, the study process continues with evaluation of a reasonable range of alternatives to develop a solution that would best meet the Purpose and Need. In addition to these Build Alternatives, a No Build – or do nothing – scenario will be assessed.

FHWA and ADOT have prepared a statement of the Purpose and Need for I-11, which is based on key transportation-related issues identified in previous studies, and which have been refined through agency coordination and public involvement during the scoping process (May-July 2016). The Purpose and Need statement is available on the Study Documents page.

The Federal Highway Administration and the Arizona Department of Transportation will be preparing a Tier 1 Environmental Impact Statement for the Interstate 11 Corridor from Nogales to Wickenburg in compliance with the National Environmental Policy Act and other regulatory requirements. NEPA was enacted by Congress in December 1969 and signed into law in January 1970. It was the first major environmental law in the United States that established the nation’s environmental policies. Under NEPA, federal lead agencies, such as the FHWA, are required to consider impacts of a proposed action on social, cultural, natural and economic resources.

The environmental review process under NEPA also provides an opportunity for you, the public, to be involved in the decision-making. It helps you understand what is being proposed; allows you to offer your thoughts and ideas on alternative ways to accomplish what is being proposed; and seeks your comments on the potential environmental effects and possible mitigation required for the proposed action.

Community members have valuable information about places and resources that they value and the potential effects that proposed actions might have on those places and resources. NEPA provides you with multiple opportunities to work with the FHWA and ADOT so they can take your information and feedback into account.

The graphic below shows the general steps of the environmental review process in preparing the Tier 1 EIS, including the opportunities for public and agency comments. We have completed the second step shown on the graphic (Conduct Scoping) and are now moving into the next step (Develop and Screen Alternatives).


It takes many people, from the planning phase through construction, to take a proposed project like Interstate 11 from an initial concept to a transportation solution. With a three-year environmental study that began recently for a corridor between Nogales and Wickenburg, here’s a quick rundown of who’s involved.

Lead agencies

The Federal Highway Administration is the federal lead agency and the Arizona Department of Transportation the local study sponsor for the ongoing Tier 1 Environmental Impact Statement required under the National Environmental Policy Act. Together, they lead the environmental review process and guide involvement from others.

Cooperating agencies

These include federal agencies with jurisdiction or special expertise regarding environmental impacts. Other agencies or tribal governments may also qualify if the Federal Highway Administration concurs. Cooperating agencies typically have a higher degree of involvement in the environmental review process.

Participating agencies

Certain federal, state, tribal, regional and local agencies with an interest in the study provide meaningful and specific insights. The role of participating agencies is broader and less-involved than that of cooperating agencies.

Public at-large

These partners range from other agencies to organizations to individuals who wish to be involved. These stakeholders tend to have specific interests in the study, such as living or working in the study area. This effort could not be done without their participation and involvement.

Enlarged version
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