Study Area Map

Note: ADOT and FHWA reduced the original study area from 1/2-mile east and west of I-17 to 1/4-mile east and west of I-17 from Loop 101 to Maricopa Traffic Interchange because of public comments received at the scoping meetings.

Study Purpose and Need: I-17, the first interstate highway to be built through the Valley, currently forms the north-south backbone of the Maricopa Association of Governments’ regional freeway system. I-17 carries a steady stream of traffic through the urban core from its origin at the I-10 Maricopa Interchange in south-central Phoenix, through the I-10 Stack interchange, to the Loop 101 interchange in north Phoenix. I-17 currently has three general purpose lanes in each direction, a high occupancy vehicle (HOV) lane in each direction between the Stack interchange and Loop 101, and auxiliary (merge) lanes in some areas of the corridor.

I-17 is currently operating at or near total capacity and is unable to accommodate projected traffic demand. The average daily traffic demand on I-17 north of the Stack interchange is projected to be 370,000 vehicles per day by 2035. Based on this level of traffic, average trip time within the study corridor is anticipated to increase by 23 percent, and congestion duration for the afternoon peak period will increase by one hour from current conditions if no capacity improvements are made. As a result of congestion, motorists will continue to experience increased travel times and delays.

Proposed improvements to this segment of I-17 are identified in the Regional Transportation Plan for Maricopa County.

The purpose of the study is to identify and recommend potential alternatives for increasing capacity on I-17 and improving traffic operations within the study corridor to meet the projected traffic demand in 2035.

Study Background: The Notice of Intent (NOI) to prepare an Environmental Impact Statement was published in the Federal Register on January 6, 2010. In February 2010, ADOT and FHWA hosted three scoping meetings as an opportunity for community members to participate in the study process. Scoping is the first step in the study process and is intended to inform and involve the public, agencies, and special interest groups. The scoping meetings marked the beginning of ADOT’s public outreach program that will continue throughout the study.

Study Update: Following the public and agency scoping meetings, ADOT conducted an alternatives development and screening process to evaluate potential options for increasing capacity on this stretch of I-17. Concepts evaluated included:

• Widening
• Express/Local Lanes
• Viaduct (elevated)
• No Build

Screening criteria to evaluate these alternatives included engineering, environmental, and cost factors, as well as community and agency input. Based on these factors, ADOT has identified potential alternatives for increasing capacity on I-17 in the study corridor.
ADOT is conducting environmental studies for these alternatives that evaluate: 

• Air quality
• Biological resources
• Cultural resources
• Environmental justice (low income and minority populations)
• Hazardous materials
• Land use
• Neighborhood considerations
• Noise
• Section 4(f) properties (parks/recreational areas, historic properties)
• Secondary and cumulative impacts
• Socioeconomic considerations
• Visual resources
• Water resources

Current Study Activity
ADOT has developed potential alternatives for increasing capacity on I-17 within the study corridor, based on engineering, cost and environmental considerations, as well as community input.

Current alternatives under consideration include:

• Two options for increasing I-17 capacity*:
• Five general-purpose lanes and an HOV lane in each direction - plus auxiliary (merge) lanes and frontage roads
• An express/local option with either three or four express lanes and an HOV lane on the I-17 mainline*, and two local lanes to the outside of the freeway mainline in each direction - plus auxiliary (merge) lanes and frontage roads and
• Constructing no improvements (the “No-Build” alternative).

*Note: varies by section of the study corridor. For the purposes of the study, I-17 has been divided into four sections. In the express/local option, access to/from express lanes would be limited. Local lanes would provide full freeway access at existing I-17 interchange locations.

ADOT and FHWA hosted public information meetings Oct. 12 and 13 to present current I-17 alternatives under consideration.

For additional information please contact: Lars Jacoby, c/o ADOT I-17 Study Team, 1655 W. Jackson St., 126F, Phoenix, AZ 85007 or via email: LJacoby@azdot.gov. To speak with an ADOT representative, you may call the Valley Freeways Project Hotline: 855.712.8530.

Throughout the alternatives development and environmental study phase, ADOT will continue to coordinate with the public and agencies by providing updates to the study and accepting study-related comments and input.

While it is too early in the process to determine if any additional right of way will be needed for the proposed improvements along I-17, ADOT and the Federal Highway Administration have standard right of way acquisition procedures in place. More information about right of way acquisition is available on the following web sites:

ADOT Right of Way
FHWA: The Uniform Relocation Assistance and REal Property Acquisition Policies Act of 1970 (Uniform Act)