Quiet Pavement Pilot Program

Back in the early 2000s ADOT started to hear from drivers who said certain stretches of Valley freeways seemed quieter than others.

ADOT and the Maricopa Association of Governments (MAG) noticed a difference, too.

It seemed that areas paved with an asphalt rubber friction course (rubberized asphalt), which MAG funded through the Regional Transportation Plan, were less noisy than freeway surfaces with cement concrete pavement.

ADOT set out to determine whether the rubberized asphalt really did make any difference when it comes to noise abatement. ADOT officials also wanted to know whether the perceived noise-reducing properties of the rubberized asphalt would last as the pavement aged.

Quiet Pavement Pilot Program

After some initial studies showed promise, ADOT, in connection with the Federal Highway Administration, developed the Quiet Pavement Pilot Program in 2003.

The program allows ADOT to use rubberized asphalt on selected freeway sections in the Valley in order to test out and study its noise mitigation properties.

According to the FHWA description, the program is intended to “demonstrate the effectiveness of quiet pavement strategies and to evaluate any changes in their noise mitigation properties over time. Current knowledge on changes over time is extremely limited. Thus, the programs will collect data and information for at least a 5-10 year period, after which the FHWA will determine if policy changes to a state DOT’s noise program are warranted.”

In other words, this study is going to show whether or not the noise mitigating effects of rubberized asphalt last the test of time.

That’s important to know because right now state DOTs cannot consider rubberized asphalt as a method to lessen highway noise. Noise walls and other tools are used primarily to meet noise abatement requirements.

If this study proves rubberized asphalt helps alleviate some road noise over years of use, states could potentially start using rubberized asphalt as an additional tool to help build quieter roads.

Findings to date

The study has shown so far …

Rubberized asphalt works best at high speeds and for average-sized passenger vehicles. It doesn’t have as much of a quieting impact at slow speeds or for larger trucks or motorcycles It’s not a solution for all climates Rubberized asphalt produces an average noise reduction of about 4 to 5 decibels over time.

Where we are today …

We have about three years remaining in the pilot study and we want to hear from you … the people who drive on Maricopa County freeways.

Public comment is an important part of the pilot program. ADOT has committed to collect and document public reactions on the rubberized asphalt for the study.