Interstate 17 (Black Canyon Freeway) Auxiliary Lane Improvements

The purpose of this PA and environmental study is to evaluate near-term freeway improvement options and recommend a preferred alternative that meets the goals of the Regional Transportation Plan Freeway Program (RTPFP), satisfies the requirements of the National Environmental Policy Act (NEPA), and obtains public support. This study will evaluate the addition of auxiliary lanes on I-17 between the entrance and exit ramps in both directions between the I-10/I-17 system interchange and 19th Avenue. Design options and potential impacts will be evaluated and considered for this study. Potential environmental impacts will be documented in an environmental document following the requirements of NEPA.

Growing traffic demand has caused the I-17 corridor from the I-10/I-17 Split Interchange to 19th Avenue to become increasingly congested. This study will evaluate the addition of auxiliary lanes between successive entrance and exit ramps to improve operations by providing additional length for traffic weaving movements in this congested corridor. 

Study related comments and questions were considered by the project team and addressed in the PA and draft environmental document. The potential improvements could include the following:

• Provide auxiliary lanes between successive entrance and exit ramps.
• Maintain existing I-17 alignment with auxiliary lane widening to the outside.
• Implement two lane entrance ramps with ramp metering.
• Increase the distance between the ramps and the frontage road intersection with the cross roads.
• Maintain the existing cross road conditions.
• Minimize right-of-way impacts.

Additional freeway improvement studies within the Interstate 10/Interstate 17 corridors include the Maricopa Association of Governments (MAG), study of the I-10/I-17 corridor, called the Spine Corridor Master Plan. The Spine Study, being performed in partnership with ADOT and FHWA, will analyze various long-term strategies to improve mobility in the corridor. The second study, by ADOT in partnership with FHWA and MAG, is the Interstate 10 Near-Term Improvements from SR 143 to the Loop 202 (Santan Freeway), which will analyze freeway capacity improvement options. All three studies will be conducted through separate efforts but will integrate information gathered for recommended overall corridor improvements. Additional information on the Spine Study can be found by calling 602.759.1916.