Connecting Phoenix with Flagstaff in central Arizona, Interstate 17 is a regional corridor joining I-10 with I-40. Heavily traveled in the Phoenix metropolitan area, I-17 is commuter freeway joining Downtown with North Mountain Village, Deer Valley and suburban areas across the north Valley.
Within Phoenix, I-17 follows the Black Canyon Freeway, one of the older freeways in the city completed in the early 1960s1. Heading north from urban areas across Deer Valley, it continues to the North Gateway area between Biscuit Flat and the Union Hills. Suburban development extends northward to the master planned community at Anthem and Rio Vista.
Beginning its ascent onto the Mogollon Plateau at New River, Interstate 17 crosses the Yavapai County line into Black Canyon City, where the lone business loop for I-17 was located until 2011. Continuing north, I-17 travels between Black Canyon and Black Mesa en route to Cordes Junction, where Arizona State Route 69 branches northwest toward Prescott.
Traversing areas of Prescott National Forest, Interstate 17 winds northeast into the Black Hills via Copper Canyon. The scenic route drops over 1,000 feet in elevation into a broad valley fed by the Verde River near Campe Verde before rising again across the White Hills.
The freeway has two major connections to the famous Sedona area, via SR 260 near Camp Verde and SR 179 near Rimrock. Northeast from Hog Canyon, I-17 runs through Coconino National Forest to the Coconio County line. The highway turns more northerly to Munds Park and Kachina Village en route to Flagstaff, where it concludes at a cloverstack interchange with I-40 and SR 89A (Milton Road).
The northernmost reaches of Interstate 17 replaced U.S. 89 Alternate. The remainder of the freeway south to Phoenix replaced state routes. U.S. 60-70-89 and U.S. 80 converged east of I-17 at Downtown Phoenix historically. U.S. 60 accompanies I-17 from Exit 201 southeast to the terminus at I-10.
I-10/17 “Spine” Corridor Master Plan
The Black Canyon Freeway, originally constructed in Phoenix between Jefferson Street and Northern Avenue with four lanes, was designed for 20,000 vehicles per day (vpd). As of 2003, the congested highway carried up to 220,000 vpd with six through lanes and two HOV lanes.
Expansion options to mitigate traffic congestion along I-17 were included in the Maricopa Association of Government 20-year Regional Transportation Plan. Funds earmarked for Interstate 17 in the plan included one study to build an upper deck to the freeway. Inspiration for the I-17 plan was derived from the construction of a second deck for the LeRoy Selmon Expressway (SR 618) in Tampa, Florida, in addition to the population density adjacent to the Black Canyon Freeway. The Selmon Expressway was expanded as part of a $350 million project between April 2004 and July 2006. Supporting a reversible roadway, six miles of elevated viaduct were added along the toll road. These were supported with single pier-supports placed in the expressway median. Within Phoenix, the second deck of the Black Canyon Freeway was considered for the stretch between Interstate 10 (Exit 199) north and Dunlap Avenue (Exit 207), a distance of eight miles.
Similar to the Tampa roadway, the I-17 roadway would have carried Express lanes with only a few entry and exit points. Some early public comments on the project were positive. A west Phoenix community group, Community Leaders Organizing for Urban Transformation (CLOUT), however were not supporters. They contested that the highway would help divide west Phoenix from the rest of the city and advocated a relocation of funds toward mass transit-based projects. Projections in 2003 outlined potential construction of the upper deck for Interstate 17 as unlikely until 2016 and 2020.1
No progress was made since and by 2011 a new I-17 Corridor Improvement Study was underway. This Arizona Department of Transportation (ADOT) study was rescinded in 2012, along with the concurrent ADOT I-10 Corridor Improvement Study. Planning, engineering and environmental information derived from those studies were folded into a new I-10/I-17 Corridor Master Plan. Referred to as the “Spine”, because of its role as the backbone of transportation mobility in the Phoenix area, the study covers 31 miles of I-17 from Loop 202 at the Pecos Stack to the south to Loop 101 at the North Stack. The first round of public meetings on the Spine Study were conducted by the Maricopa Association of Governments (MAG) in partnership with ADOT and the Federal Highway Administration (FHWA) in March 2015.
The Recommended Alternate for the Corridor Master Plan was accepted into the 2040 Regional Transportation Plan by the MAG Regional Council on May 24, 2017. ADOT, the FHWA and MAG signed a Planning and Environmental Linkages (PEL) Statement summarizing the project’s findings on March 28, 2018. Final recommendations included bringing the freeway up to current design standards, adding at least one additional lane along the entire corridor in addition to implementing a managed lane system, modernizing 24 of the 31 interchanges, and improving pedestrian and bicycle connectivity at 20 locations.