Experience Predicting Construction-Site Noise

The practical aspects of predicting construction-site noise are examined: the implementation of the prediction process, including the use of suit able source-noise emission measurement standards, the identification of p ...opagation factors, and the assumption of meteorological conditions. The application of a prooiction procedure is compared with field mea surements to verify accurac,Y and to establish appropriate design safety margins. To rstimate the site sound levels from one or more noise sources, sound attenuation was considered due to four mechanisms spreading, atmospheric absorption. ground reflections ("ground inter action"l, and barrier shielding. 'oise-source emissions were measured essentially at maximum noise-generation conditions for the equipment, based on th.~ test procedures of both the Societ.y of Automoth"e Engineers and the American National Standards Institute. Prediction accurac:y was verified for eighf sites with 19 total locations and conditions. When observed primaQ'-mal:rune sound le\'els were compared with the pre dictions, the mean error was 3 dB(A). For group equipment operations and measurement-period sound lel'els. w'hkh are subject to source oper ating condition variation and rnobjJe~equipmentmovement. the mean equivalent sound-Ie\'el o\'erprediction was approximately 6 dB(A/. Empirical measurements and analytical predictions are alternative methods to quantify the noise emissions from a site. Each has adva.T') tages and disadvantages. Measurements have the advantages of quantifying actual. existing conditions (including those that are far too complex to be readily modeled in a prediction procedure) and of being more persuasive to laypeople than predictions. However, measurements have the disadvantages of being subject to sampling errors due to source variation and meteorologicai conditions (the significance of which is often ignored) and of being relatively expen sive to perform properly. On the other hand, predictions have the advantages of permitting quantification of noise sources and condi tions that currently do not exist (e.g., the evaluation of noise controls) and of allowing the quantification of numerous locations relatively mexpensively. However. predictions have the disadvantages of being subject to erron; due to site-configuration simplification and activity description inaccuracies and of not being highly persuasive to lay people. Measurements and predictions are best used to complement each oL1er. with the empirical measurements verifying and calibrating the analytical predictions. The prediction of noise from a facility or operation is often neces sary as part of a plan-appro\ a1 procedure to demonstrate compliance \\'tth (a) local noise ordinances, (b) an environmental assessment process for federally funded projects. or (c) the overall facility design to assure community acceptability of a.'1 industrial activity. Often these operatiom involve diesel-fuel-engined mobile equipment. Sites or operations requiring such predictions include transportation hubs