ADOT recommends walls to decrease future freeway noise

Some Ahwatukee Foothills residents are concerned about noise that the proposed South Mountain Freeway could generate. And they fear noise barriers would create unsightly walls.

Members of the Arizona Department of Transportation (ADOT)-led freeway study team talked about how the freeway would increase noise levels in some areas and suggested ways to mitigate the sound during a South Mountain Citizens Advisory Team meeting last week in south Phoenix.

Arizona addresses noise in residential areas when noise levels reach 64 decibels while the federal standard to mitigate noise in those areas is 67 decibels, Tim Tait, ADOT spokesman and study team member, said via e-mail. The threshold of pain to human ears is about 140 decibels, according to the freeway study team.

"Construction and operation of this proposed freeway would introduce a major noise source into an area where such noise may not have existed in the past," a study team report stated.

Studies show that currently noise along the proposed freeway alignment ranges from 44 to 64 decibels, Tait said. If walls or other sound barriers were not used, the noise levels from the proposed freeway could range from 61 to 79 decibels in residential areas along the route, he said.

The initial noise barriers installed would be designed to reduce noise from the 56- to 68-decibel range, Tait said via e-mail.

Noise walls, which are generally 10 to 20 feet tall, could reduce sound, as could using rubberized asphalt on the freeway, he said.

The freeway would pass homes, schools, parks, churches and "other land uses sensitive to traffic noise," the study team report said. It would be built mostly at grade but if it were built below grade the noise would be reduced "somewhat," Tait said. Noise walls would still be required to meet the state standards, he said.

"Nobody denies the below-grade option is quieter and less obtrusive visually," Chad Blostone, Ahwatukee resident and advisory team member said after the meeting. "They need to get back to the table and look at some different design options."

The study team has said it would be more expensive to build the freeway below ground along the majority of the route and would displace more homes.

Ahwatukee resident John Rodriguez, also on the advisory team, said a diagram the study team presented showed most of Pecos Road would be "walled in" to mitigate noise.

"The great wall of Pecos is coming," Rodriguez said after the meeting, adding that the Lakewood Community Association, which he represents, would "be subject to noise."

The advisory team will eventually recommend whether it thinks the freeway should be built.

The team is expected to meet next at 5:30 p.m. July 24 at South Mountain Community College, 7050 S. 24th St. Information: www.azdot.gov/Highways/Valley_Freeways/Loop_202/South_Mountain/CATSchedule.asp.