Thirty-six adolescent Common Linden trees were placed in a simulated street canyon near Schiphol Airport’s Kaagbaan runway, where sound, weather, and flight data were collected between February through May. Two additional configurations of the trees were also tested to evaluate the effect of planting density and patterns on scattering
and reflecting noise. Trends in sound pressure levels measured inside the street canyon were compared to levels measured by a reference microphone, and a linear regression analysis was performed to determine the effect of weather and trajectory variables on the differences in sound pressure levels between these two environments. Between 0.68 and 3.3 dB of noise attenuation were observed in the experimental courtyard for arriv- ing flights, versus between -2.65 and 0.5 dB of noise attenuation for departing flights. Furthermore, while around 10 percent (R2 =0.099) of variation in the noise attenuation
of arriving flights could be explained by flight trajectory and weather variables alone, this percentage was significantly higher for departing flights (R2 =0.46). These results are in line with previous research which found that the interaction of building properties with meteorological variables and flight trajectory have the most influence on sound propaga- tion of aircraft noise within a street canyon environment, but also suggest that vegetation can play a role in mitigating noise pollution. Further research is required to determine if the presence of adult leaves or the psychological effects of greenery on the human per- ception of aircraft noise pollution could augment the modest noise pollution attenuation effects of trees seen in this experiment.
Author: Lanie Preston