Noise attenuation by green belts

This paper outlines the results of noise attenuation investigations at eigh t planatation sites in Jharia (JCF) and Raniganj (RCF) coalfields in India. With a B&K Type 4224 noise source operated on spectrum I mode, the maximum total noise attenuation for Leg at 50 m depth of the green belt was found to be within 188-21.1 dB (A) in JCF and 18.7-21.0 dB (A) in RCF. Excess noi se attenuation (Leq) exclusively due to green belts in JCF and RCF was 3.3- 6.0 and 3.6-5.7 dB (A) respectively. Excess attenuation for higher frequenc ies( > 250 Hz) was more [ > 4 dB (A)] than that for lower frequencies ( les s than or equal to 125 Hz). Average trend of total noise attenuation (in pe rcentage) at different depths of the green belt was evaluated to compute th e minimum desired thickness of green belt for different locations in coal m ining complexes. Based on characterization of the plantation sites and meas ured noise attenuation, a multivariable linear relationship was established for excess noise attenuation. (C) 2000 Academic Press.