All three improvements are vital to preserve the integrity and safety of State Route 89A. The highway was built in a canyon with a lot of rock-cut faces, which erode over time due to weather conditions. This leads to large rocks, sediment and other debris on the roadway, which creates significant safety and maintenance issues. The improvements include: 

No, this freeway is not tolled and is funded by state, federal, and local dollars.

Ports of entry monitor all commercial traffic entering Arizona for registration, taxes, size and weight restrictions, commercial driver license requirements, insurance requirements and equipment safety requirements, and issue permits as required. ADOT’s Enforcement and Compliance Division further works to ensure the safe and efficient movement of commercial motor vehicles on highways throughout Arizona.

Arizona highways, like most highways across the United States, are open to all kinds of traffic, so long as the cargo being carried is in accordance with U.S. Department of Transportation regulations for the specific type of cargo. The Arizona Department of Transportation has a few locations in the state with hazardous cargo restrictions, but these restrictions are based on emergency response issues or roadway design limitations specific to that location.

The SMF was not constructed to create a "truck bypass" for downtown Phoenix. The freeway is part of a transportation system developed to improve mobility in the region by increasing capacity and providing traffic alternatives—including truck traffic—to other, already congested routes. As with all other freeways in the MAG region, trucks use the SMF for the through transport of freight, for transport to and from distribution centers, and for transport to support local commerce.

Factors considered in the environmental study were the amount of truck traffic that would use the freeway and its potential impact on the surrounding community. The MAG regional travel demand model forecasts approximately 10 percent truck traffic on the South Mountain Freeway in 2035. The forecasted truck traffic is based on existing traffic studies and projected socioeconomic data. This percentage is similar to current traffic conditions on I-10 between Loop 101 and I-17 and on US 60.

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.