Description
Altering the pavement surface can reduce noise generated by traffic on a highway. Aged Portland cement concrete pavements (PCCP) are commonly altered or improved by grinding or by sawing grooves into the surface to provide better friction characteristics and in some cases to reduce rolling tire noise. Asphalt concrete surfaces are milled and replaced with a new asphalt surface. Recent improvements to urban freeways in Arizona have used thin (2.5 cm or less) open graded friction courses manufactured with asphalt-rubber binder where the binder is comprised of 80% asphalt and 20% ground tire rubber. The thin layers of Asphalt-Rubber Open Graded Friction Courses (A-R OGFCs) placed by the Arizona Department of Transportation have been noted for long lasting performance while improving the ride characteristics of aged PCCP. Additionally, although it was not placed for this purpose, the rubberized asphalt surfaces give significant reductions in traffic noise when compared to adjacent Portland concrete cement surfaces. In this study the reduction has been noted to be from 9 to 6 dB (A) at distances from 15-120 meters (50-400 feet) from the highway.
