The Arizona Department of Transportation is investigating possible improvements to a stretch of Interstate 10 in Phoenix to address heavy congestion and frequent crashes.
In collaboration with the city and the Maricopa Association of Governments, ADOT will study the I-10 corridor between the Deck Park Tunnel and I-10/I-17 Split interchange, where congestion and crashes are expected to increase. The study area encompasses State Route 51 south of Thomas Road, the Loop 202 (Red Mountain Freeway) west of 24th Street and the entire interchange of I-10, SR 51 and Loop 202, known as the “Mini-Stack.”
Travel times on the corridor are estimated to increase by up to 60% by 2050. It saw more than five crashes per day on average from 2016 to 2021, mostly rear-end and sideswipe accidents.
Project goals, beyond improving safety and reducing congestion, include improved regional access to downtown Phoenix and the Phoenix Sky Harbor International Airport and more high-occupancy vehicle access. Potential improvements include:
- I-10 operational and safety enhancements, such as reducing merging and weaving movements and HOV lane continuity/connectivity
- Traffic interchange and system ramp improvements and freeway and ramp improvements, including additional on- and off-ramps, relocating on- and off-ramps, additional general purpose and/or HOV lanes and barrier-separated ramp or roadway concepts
- Potential collector-distributor road concepts to reduce weaving and improve reliability
- Maintaining or improving regional and local access and connectivity serving Phoenix Sky Harbor International Airport
- Improvements to some adjacent streets and pedestrian/bike connectivity needs including relocating pedestrian crossings
Next steps include ADOT preparing a design concept report and environmental assessment to potentially tap federal funds. A public meeting is scheduled this fall, and design work is expected to begin in Spring 2028. No construction start time and estimated project cost have been announced.
The new study builds on previous ones by the Maricopa Association of Governments on the corridor, including the 2023 Interstate 10 Freeway Corridor Study – Deck Park Tunnel to I-10/I-17 Split, which examined safety and operational deficiencies, and a 2025 study on improvements, which estimated a project cost of $866 million.
