Sonoran Corridor (SR 410) Tier 1 Environmental Impact Statement

Sonoran Corridor (SR 410) Tier 1 Environmental Impact Statement

State Route 410 Sonoran Corridor Study


Study Overview

In May 2017, the Federal Highway Administration (FHWA), in coordination with the Arizona Department of Transportation (ADOT), issued the Notice of Intent that started the environmental review process for the Sonoran Corridor, a potential new corridor route that would connect Interstate 19 and Interstate 10 south of Tucson International Airport.  A Tier 1 Environmental Impact Statement (EIS) was prepared as part of this process in accordance with the National Environmental Policy Act (NEPA) and other regulatory requirements.

As part of the NEPA process, ADOT and the FHWA are engaging and involving stakeholder agencies, organizations, and members of the public throughout the study process.

What is a Tier 1 Environmental Impact Statement (EIS)?

In a Tier 1 EIS, an agency analyzes and documents the environmental impacts a program or project may have on a broad scale. A Corridor Selection Report (CSR) will be developed during the early stages of the Tier I EIS.   The CSR is a technical document that assesses a wide range of corridor options through a robust evaluation process that uses environmental, geographical, topographical, socio-economic, agency and public input, and other planning information to help identify opportunities and constraints.  The purpose of a CSR is to document the universe of corridor options considered and help identify a reasonable range of Build alternatives that will be carried forward in the Tier 1 EIS document for further analyses.

After a reasonable range of Build alternatives is identified, the potential social, economic, and natural environmental impacts of the No-Build Alternative (the do-nothing option) and Build alternatives will be analyzed and documented in the Tier 1 EIS.  Each Build alternative is expected to be 2,000 feet in width.   If one of the build alternatives is selected as the Preferred Corridor Alternative, a phased implementation plan will be developed and documented in the Draft Tier 1 EIS. A phased implementation plan includes smaller segments of the Preferred Corridor Alternative, also known as Sections of Independent Utility (SIU).  The SIU may advance as separate, independent projects following completion of the Tier 1 EIS process. 

In conclusion, FHWA will issue a final decision document that combines both the Final Tier 1 EIS and Record of Decision, and will identify the Selected Corridor Alternative and commitments that will be in mitigation for any potential environmental impacts.

What are the next steps after completion of the Tier 1 EIS process?

The Tier 1 EIS will provide a roadmap for advancing the project to the next phase – called Tier 2 environmental studies. During the Tier 2 environmental process, ADOT and FHWA will conduct additional environmental and engineering studies that examines each SIU within the Selected Corridor Alternative, in greater detail.


Following several years of study, technical analysis and input from communities and stakeholders, the Arizona Department of Transportation has selected a final 20.47 mile corridor through Pima County. The Final Tier 1 Environmental Impact Statement (EIS) and Record of Decision (ROD), released November 5, 2021, identifies the selected corridor as Corridor Alternative 7, which stretches between Interstate 19 (I-19) and Interstate 10 (I-10), south of the Tucson International Airport in Pima County. 

Sonoran Corridor Preferred Corridor Alternative

Sonoran Corridor Preferred Alternative



Final Environmental Impact Statement & Record of Decision



Sonoran Corridor Alternatives 

Sonoran Corridor Alternatives

Sonoran Corridor Study: Recommended Reasonable Range of Alternatives for further study. These were presented during the March 7, 2019 public meeting and open for comments through April 7, 2019. For more information please contact [email protected].

Sonoran Corridor Alternatives Map


Sonoran Corridor Preferred Alternative

Public Meetings

Public Hearings were held in 2020

Arizona Department of Transportation and the Federal Highway Administration held an in-person public hearing Tuesday, Dec. 1, and a virtual public engagement event Dec. 3, to provide information on a study that would connect Intestate 19 and Interstate 10 in Tucson. The public has the opportunity to make formal comments about the Draft Tier 1 Environmental Impact Statement (EIS).

In Person Public Hearing

  • When: Tuesday, Dec. 1, from 5 p.m.  8 p.m. (presentation will play continuously)
  • Where:  DoubleTree Suites – Tucson Airport – Ballroom Royale, 7051 S. Tucson Blvd., Tucson, AZ 85756  *Reservations required* 

Virtual Public Engagement Event

  • When: Thursday, Dec. 3, 5 p.m.– 8 p.m
  • Join by phone by calling 408.418.9388 and entering the meeting number (access code) 146 242 8979 or join online, use the meeting number (access code) 146 242 8979 and password SCEIS2020.
  • For Spanish (call-in only), call 408.418.9388 and enter the meeting number (access code) 146 978 0659. 

Participants have the opportunity to make a comment to the panel that is recorded by the court reporter. Participants can join at any time and will be able to listen to others’ comments about the Draft Tier 1 EIS.


Past Public Meetings

Thursday, March 7, 2019

5:30 – 7:30 p.m.
Presentation at 6:00 p.m

DoubleTree Suites by Hilton Tucson Airport
7051 South.Tucson Boulevard
Tucson, AZ 85756

This public information meeting provided information on the draft Corridor Selection Report (CSR) that detailed the alternative analysis completed by meeting date.

Public input on the draft CSR helps the study team identify the reasonable range of corridor alternatives that will be considered for further evaluation in the Tier 1 EIS document.


Wednesday, Sept. 26, 2018

5:30 – 7:30 p.m.

Desert Diamond Casino Exhibit Hall
7350 South. Nogales Highway
Tucson, AZ 85756

June 7 & June 8, 2017

Public scoping meetings

June 7, 2017
Radisson Hotel Tucson Airport
4550 S. Palo Verde Road
Tucson, AZ 85756

June 8, 2017
Santa Cruz Valley United Methodist Church
71 E. Sahuarita Road
Sahuarita, AZ 85629

2017 Display Boards


Additional public meetings will be scheduled as this study progresses. ADOT will provide information in advance of all public meetings. 



Draft Environmental Impact Statement (DEIS)


Contact Us

Your input is important. Please share your thoughts on this study through the methods outlined below. Thank You!

Email  Email: [email protected]

Smart PhoneToll-free bilingual information line: 855.712.8530

Mail  Mail: ADOT Communications Sonoran Corridor Team
                 1221 S. Second Ave. Tucson, AZ 85007

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