Effectiveness of Embankment and Afforestation for Countermeasures against Airport Noise

Abstract

A long-range plan of embankment and afforestation has been propelled at New Tokyo International Airport so that local communities in the sidelines of the runway can recover a quiet and comfortable living environment. Recently, the effectiveness of both the bank and the wood for noise countermeasures was examined from outdoor measurements using real aircraft noise and an artificial sound source. With neither the bank nor the wood being able to be removed, noise measurements without screens were carried out at substitute site locations with source and sound propagation conditions equivalent to those at the bank and the wood. The result of the examination suggests that the bank brings a certain definite amount of sound insertion loss, i.e. approx. 7-12dB at 100m and 6-9dB at 300m behind the bank, at least, under calm or low vector wind conditions. On the other hand, the wood brought sound insertion loss of only 1-2dB. However, a difference of ground surface conditions, which affect sound propagation, between the measurement without the wood and that with the wood prevented definite examination of the effectiveness.