Service Agreements
Arizona Department
of Transportation (ADOT):
In April of
2003, ADOT received approval from the FHWA to allow the use of
pavement surface type as a noise mitigation strategy, which was
granted with the condition that Arizona would be a pilot program
with specific research objectives and requirements. The research
is intended to validate the efficacy of using Asphalt Rubber
Friction Courses (ARFC) as a noise mitigation strategy. Over
several years ADOT will overlay much of the Portland Cement
Concrete Pavement (PCCP) in the valley with a one-inch thick ARFC
surface. Where the ARFC is placed and noise walls are required,
the walls will be reduced approximately 8 ft in height due to the
use of the ARFC surfacing. ADOT, supported by a consultant, has
begun to monitor four sites across the Phoenix Metropolitan area
for traffic-generated noise over a ten-year period to evaluate the
effectiveness of ARFC. Recent experiences, however, suggest that
traditional noise abatement approaches (e.g. the use of walls) can
be defeated by environmental conditions. Therefore, the ASU group
was enlisted by ADOT to monitor environmental conditions that
occur during acoustic monitoring, with the purpose of establishing
actual environmental conditions at the time of acoustic monitoring
and to determine any impacts on acoustic monitoring results. An
Intergovernmental Service Agreement was signed between ADOT and
ASU in 2004, and the first phase of funding begun in 2005. It was
extended in 2006.
In the
first (completed) environmental testing phase, the effects of
winds on noise propagation were studied under neutral conditions.
However, the effects of inversions have not been studied, although
they are known to be important; and this is theme of the ongoing
work.
