Page 40 - 2016Winter

Judith L. Rochat
Postal:
6965 Abbottswood Drive Rancho Palos Verdes, California 90275 USA
Email:
jrochat@atsconsulting.com
Darlene Reiter
Postal:
504 Autumn Springs Court, #11 Franklin, Tennessee 37067 USA
Email:
dreiter@bowlbyassociates.com
Highway Traffic Noise
Understanding highway traffic noise sources and how to abate them and addressing health concerns and environmental protection legislation and regulations.
Introduction
More than 45 million people live, work, or attend school within 300 feet of a ma- jor transportation facility in the United States alone (http://acousticstoday.org/ roadway). These facilities include heavily traveled highways that can cause adverse noise effects. Figure 1 shows a major highway with adjacent communities. Such
Figure 1. Aerial view of highway and surrounding community. Image from Google Earth.
geometries with communities in close proximity to highways are not unusual.
In addition to an- noyance and speech interference, re- cent studies have reported on links between highway traffic noise and health effects. The World Health Or- ganization (WHO) reported on envi- ronmental health effects, including
heart disease, sleep disturbance, and cognitive impairment in children. WHO states, “... at least one million healthy life years are lost every year from traffic- related noise in the western part of Europe” (WHO, 2011). These human health is- sues as well as the effects of highway traffic noise on wildlife are a growing concern.
To help minimize the effects of highway traffic noise, researchers and practitioners must understand the noise sources, how the sound propagates to nearby commu- nities, and how to reduce noise levels at the source, during propagation, or at the receiver. Further challenges lie in establishing and implementing highway traffic noise policies. Figure 2 highlights the major elements of highway traffic noise.
Highway Traffic Noise Sources
Highway traffic noise is caused by tire-pavement interaction, aerodynamic sources (turbulent airflow around and partly through the vehicle), and the vehicle itself (the power-unit noise created by the engine, exhaust, or transmission). At highway speeds, tire-pavement interaction generally is the most dominant source (Sand- berg and Ejsmont, 2002).
38 | Acoustics Today | Winter 2016 | volume 12, issue 4 ©2016 Acoustical Society of America. All rights reserved.