THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

350 13. Criteria and Regulations for Noise ControlThe test is to be conducted during dry weather without the presence of dust orpowdery snow.The EU has no exterior noise standards for railroad equipment because of interminglingwith equipment from outside the EU and differences in rail gauges.Railroads have used, on their own, a number of noise standards such as the InternationalUnion of Railways ORE E82/RP4 and the ISO 3095: 1975.Highway Construction NoiseAn interesting development in EU is the use of sound power as a noise measure,rather than sound pressure at a single point in space, for earth-moving andother construction equipment. Sound power measures the total noise emanating inall directions from a source. The fundamentals of sound power measurement aregiven in Chapter 9, Sections 9.17 et seq.; and details are given in the EU directives95/27/EU, 89/514/EEC, 86/662/EEC, 84/533-536b/EEC, and 79/113/EEC.The distribution of measurement positions specified by 79/113/EE is given in ahypothetical hemisphere enclosing a stationary piece of earth-moving equipment.Sound pressure is measured at the prescribed measurement points, which is convertedinto sound intensity, applying the far-field approximation and integratedto yield sound power. The sound power measurement would be more accurate ifsound intensity measurements were used instead of sound pressure. In its currentform the test uses only half of the measurement points specified in 79/113EEC. Asimilar sound power test was developed for lawn mowers in 84/538/EEC.amendedby 88/181/EEC.New noise limits came into effect at the end of 1996 for earth-moving machineryof net installed power less than 500 kW. Machines with power exceeding 500 kWoperate in quarries and mines and so are considered to have a negligible effect oncommunity noise. For the period between 1996 and 2001, the permissible soundpower levels L WA ,inA-weighted decibels relative to 1 pW, are given by1. Tracked vehicles (except excavators):L WA = 87 + 11 log P for L WA ≥ 107 (13.21)2. Wheeled bulldozers, loaders, excavators loaders:3. Excavators:L WA = 85 + 11 log P for L WA ≥ 104 (13.22)L WA = 83 + 11 log P for L WA ≥ 96 (13.23)where P is the net installed power of the construction vehicle in kilowatts. Belowthe lower limit given above, the machine automatically passes the test. After2001, the numerical A-weighted decibel values in Equations (13.21–13.23), includingthe lower limits, are reduced by 3 dB(A). The coefficient 11 remainsunchanged.