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A noise barrier (also called a soundwall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect inhabitants of sensitive land use areas from noise pollution. Noise barriers are the most effective method of mitigating roadway, railway, and industrial noise sources – other than cessation of the source activity or use of source controls. In the case of surface transportation noise, other methods of reducing the source noise intensity include encouraging the use of hybrid and electric vehicles, improving automobile aerodynamics and tire design, and choosing low-noise paving material. Extensive use of noise barriers began in the United States after noise regulations were introduced in the early 1970s. ==History== Noise barriers have been built in the United States since the mid-twentieth century, when vehicular traffic burgeoned. In the late 1960s, analytic acoustical technology emerged to mathematically evaluate the efficacy of a noise barrier design adjacent to a specific roadway. By the 1990s, noise barriers that included use of transparent materials were being designed in Denmark and other western European countries.〔Benz Kotzen and Colin English (1999) ''Environmental Noise Barriers: A Guide to Their Acoustic and Visual Design'', Published by Taylor & Francis, ISBN 0-419-23180-3, 165 pages〕 Below, a researcher collects data to calibrate a roadway noise model for Foothill Expressway. The best of these early computer models considered the effects of roadway geometry, topography, vehicle volumes, vehicle speeds, truck mix, roadway surface type, and micro-meteorology. Several U.S. research groups developed variations of the computer modeling techniques: Caltrans Headquarters in Sacramento, California; the ESL Inc. group in Palo Alto, California; the Bolt, Beranek and Newman〔John Shadely, ''Acoustical analysis of the New Jersey Turnpike widening project between Raritan and East Brunswick'', Bolt Beranek and Newman, 1973〕 group in Cambridge, Massachusetts, and a research team at the University of Florida. Possibly the earliest published work that scientifically designed a specific noise barrier was the study for the Foothill Expressway in Los Altos, California.〔C.M. Hogan and Harry Seidman, ''Design of Noise Abatement Structures along Foothill Expressway, Los Altos, California'', Santa Clara County Department of Public Works, ESL Inc., Sunnyvale, California, October, 1970〕 Numerous case studies across the U.S. soon addressed dozens of different existing and planned highways. Most were commissioned by state highway departments and conducted by one of the four research groups mentioned above. The U.S. National Environmental Policy Act〔 * U.S. National Environmental Policy Act, enacted January 1, 1970〕 effectively mandated the quantitative analysis of noise pollution from every Federal-Aid Highway Act Project in the country, propelling noise barrier model development and application. With passage of the Noise Control Act of 1972,〔Public Law No. 92-574, 86 Stat. 1234 (1972)Noise Pollution and Abatement Act of 1972, codification amended at 42 U.S.C. 4901-4918 (1988)〕 demand for noise barrier design soared from a host of noise regulation spinoff. By the late 1970s, more than a dozen research groups in the U.S. were applying similar computer modeling technology and addressing at least 200 different locations for noise barriers each year. As of 2006, this technology is considered a standard in the evaluation of noise pollution from highways. The nature and accuracy of the computer models used is nearly identical to the original 1970s versions of the technology. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Noise barrier」の詳細全文を読む スポンサード リンク
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