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.