A Method for the Prediction of Noise Levels at Construction Site Boundaries

Abstract

The regulation and measurement of noise levels at construction sites in Japan are examined. From fiscal years 1971-1976, Japan's investment in construction increased from $17,080 to $23,880 million. Prior to starting any construction project, legislation requires that noise pollution levels caused by construction equipment at job site boundaries be determined. This requirement has led to the development of a simple, inexpensive, but relatively precise computer program and method for noise prediction. Computer program input requires measuring each machine's noise level, and the method's accuracy has been experimentally verified by field tests. Field testing shows that the evaluation of noise emitted by construction equipment is determined by the sound source's power level. To obtain this level with great accuracy, at least 10 microphones must be placed around the machine. When simple measurement is appropriate, four microphones will provide acceptably accurate results. A 10-meter radius of an imaginary hemisphere on which microphones are located is preferable; the microphone arrangement recommended in International Standards Organization 4872 is reasonable. In general, engine high idle should be the standard operating condition. If there are other noticeable sound sources, they should also be taken into consideration. When prediction with high accuracy is required, it is necessary to consider sound source directivity, land layout, interference of sound waves, and excess attenuation.