Frequently asked questions

Chapter 3 of the Final Environmental Impact Statement (FEIS) states traffic projections estimate approximately 117,000 to 190,000 vehicles daily would use the South Mountain Freeway in 2035.

Air quality impacts were estimated through sophisticated computer modeling based on predictions of the amount and nature of traffic under worst-case scenarios. The emissions models are based on extensive emissions testing that the U.S. Environmental Protection Agency (EPA) has conducted on thousands of vehicles representative of the ages and models of the vehicle fleet on the roads today.

While efforts to study alternatives on Community land were attempted, the Community has long held a position of not allowing the freeway to be located on its land. For example, a coordinated referendum of Community members to favor or oppose construction of the freeway on Community land or to support a no-build option occurred in February 2012, and Community members voted in favor of the no‑build option. Therefore, the freeway cannot be located on Community land.

The study did consider a variety of transportation alternatives, modes, and strategies that would fit into the Regional Transportation Plan, including transit. The freeway option was determined to best meet the purpose and need for the project, following an extensive screening process which included evaluation of additional benefits such as system linkage, regional mobility, and consistency with regional and local long-range plans.

Public input was a vital component during the environmental study phase and was solicited from project inception through key milestones in the Draft and Final Environmental Impact Statement (EIS) processes. The interests and needs of the public, along with all other social, economic and environmental issues and impacts, were fully analyzed during the study phase of the project.

The route for the freeway was determined through a multidisciplinary process to identify a range of reasonable alternatives that were studied in detail in the Environmental Impact Statement. The study process involved identifying, comparatively screening, and eliminating alternatives based on:

The SMF has been a critical part of the MAG Regional Freeway Program since it was first included in funding approved by Maricopa County voters in 1985. The SMF was also part of the Regional Transportation Plan funding passed by Maricopa County voters in 2004 through Proposition 400. The SMF is a key component of the region’s adopted multimodal transportation plan and the Regional Freeway and Highway System and is the last piece to complete the Loop 202.

The 40th Street, Estrella Drive and Vee Quiva Way interchanges provide the Gila River Indian Community direct access to and from the freeway. The Gila River Indian Community is responsible for connecting to the traffic interchanges, in coordination with appropriate jurisdictions.

The South Mountain Freeway will be constructed as an eight-lane freeway (three general purpose lanes and one HOV lane in each direction). There are no current plans to widen the freeway in the future.

ADOT no longer paves its highway bridges with rubberized asphalt. This is because the rubberized asphalt must be removed and replaced each time a bridge needs to be inspected or if a repair must be made. By not paving bridges with rubberized asphalt, ADOT reduces costs, as well as the need to close or restrict freeways for asphalt removal or replacement. And because rubberized asphalt is a temperature-sensitive product, bridges could be repaved only during optimal conditions that occur twice a year (spring and fall).

Rubberized asphalt has been used on the SMF to provide a smooth driving surface. It has the added benefit of reducing noise levels by up to four decibels. This material—used for more than 20 years to resurface highways and city streets in Arizona—consists of regular asphalt pavement mixed with recycled rubber tires. In addition to the benefits it provides on the roadway, rubberized asphalt also reduces the number of used tires in landfills. Final rubberized asphalt paving will occur in the spring of 2020.

Yes. ADOT continues to evaluate locations where light could be redirected while maintaining the safety of the motoring public. Careful consideration and planning go into adjusting lighting on a mainline urban freeway

Noise walls were built in locations that warranted noise mitigation in compliance with state and federal regulations based on noise modeling completed prior to construction. ADOT will continue to measure noise levels along the entire freeway corridor to evaluate impacts and ensure that noise levels remain at or below what is permitted by state and federal regulations. ADOT’s policy is to reduce the impact of freeway noise on adjacent homes, schools and churches by building sound walls or berms.

A double roundabout interchange resembles the shape of a dog bone from an aerial view. This type of interchange will be constructed at Estrella Drive. Features of a double roundabout interchange:

• Reduces conflicts between vehicles
• Minimizes right of way impacts
• Improves efficiency
• Provides a safer design by eliminating the potential for perpendicular collisions

A Diverging Diamond Interchange (DDI) is based on a standard diamond interchange common in Arizona, but with one major difference —traffic shifts briefly on the left side of the road between highway ramps, allowing left turns without crossing oncoming traffic. The freeway will feature two half-DDIs in the Pecos Segment, as there are no connection points to the south. Features of a DDI:

A shared-use path is a physically separated path adjacent to a highway. It accommodates pedestrians, bicyclists and other forms of non-vehicular traffic. The 20-foot wide shared-use path is being constructed between 40th Street and 17th Avenue directly south of the freeway in the Pecos Segment. While C202P is responsible for the design and construction of the shared-use path, the city of Phoenix will be responsible for maintaining the path. Additionally, the shared-use path will provide connectivity complementing the city of Phoenix Comprehensive Bicycle Master Plan.

Interchange locations were determined during the environmental phase of the project, based on traffic modeling and regional mobility needs. During this process, ADOT coordinated with the city of Phoenix and a Citizens Advisory Team to identify interchange locations. Initially, interchanges were not planned for 32nd Street and Vee Quiva Way. The interchanges were added to the project after construction began in 2016 at the request of area residents, businesses and other key stakeholders and following a re-evaluation of the environmental study.

Fifteen traffic interchanges will be located at the following major street crossings:

Since the P3 method encourages innovation and optimization of efficiencies, the current freeway design incorporates some changes from the early design concepts that minimize the right of way impacts while increasing safety and reducing traffic restrictions during construction. Innovation and efficiency examples throughout the freeway corridor include:

Half diverging diamond interchanges at Desert Foothills Parkway and 17th Avenue

Modifying interchanges to improve traffic operations and minimize right of way requirements

Yes. The state retains ownership of the SMF, and C202P is granted a non-exclusive license (not ownership) for 30 years to access and use the freeway and its structures to carry out operations and maintenance. C202P must return to the state a freeway in excellent condition at the end of the maintenance period in 2050. Although C202P must maintain the freeway, ADOT can make improvements, if warranted, at its own cost.