According to the most recent data available from 1987, noise from highway traffic affects more than 18 million people in the United States.As highway systems continue expanding, increased traffic volumes result in higher levels of traffic noise for residents of adjacent neighborhoods.The level of noise emitted by trucks has decreased by 3 d B(A) in the past 20 years. Road measures to reduce highway traffic noise include restricting truck access and adjusting the timing of traffic signals.Other options to consider early in the planning stages are depressing the highway (constructing the highway below grade) or moving it farther away from sensitive areas.Another option is to create attractive open spaces next to roads for recreational uses.Undeveloped open space can serve as a buffer zone between the highway and residential areas.Most people prefer the noise levels in their homes to be in the 40-45 d B(A) range, similar to the levels found in a small office.A reduction of sound from 65 to 55 d B(A) reduces the loudness of the sound by one half, while a reduction of sound from 65 to 45 d B(A) results in a loudness reduction of one quarter.
Sound Basics Acousticians define sound as a sensation in the ear created by pressure variations or vibrations in the air.
FHWA encourages developers, government officials, planners, and private citizens to consider ways to address highway traffic noise before—rather than after—frustrating problems arise.
One solution is noise-compatible land-use planning. Through advance planning and shared responsibility, local governments and developers, working cooperatively with Federal and State governments, can plan, design, and construct new development projects and roadways that minimize the adverse effects of noise from highway traffic.
In fact, existing Federal legislation already prohibits FHWA participation in the construction of most noise barriers for new development that occurs near existing highways.
(See Title 23 of the Code of Federal Regulations, 23 CFR 772.13(b).) "A lot of municipalities just don't even think about noise," says Eric Zwerling, director of the Rutgers Noise Technical Assistance Center at the State University of New Jersey and president of the Noise Consultancy, LLC, "but the bottom line is that it's much, much cheaper to design for quiet than to remediate afterwards.