Principal Components Regression of Onboard Sound Intensity Levels

Abstract

Roadways paved with open graded asphalt mixes typically generate lower traffic noise levels as compared to other types of pavements. A program was initiated in 2005 in California to evaluate the effectiveness of noise reducing surfaces over time and the pavement characteristics affecting those noise levels. In this study, tire/pavement noise was measured using the onboard sound intensity method. Data were collected on four different types of mixes: conventional open graded asphalt concrete, rubberized asphalt concrete that are open graded, rubberized asphalt concrete that are gap graded, and dense graded asphalt concrete mixes. A total of 72 field pavement sections that were at that time less than 8 years old were included in the study. Various pavement characteristics were measured and their effects on noise levels were evaluated using principal components regression, in addition to ordinary least-squares regression. This research confirmed that open graded pavements exhibit reduced tire noise compared to dense and gap graded mixes and quantified this reduction for typical mixes in California.