Prediction Of Road Traffic Noise Attenuation DueTo Distance, Ground Absorption And Gradient

The propagation of road traffic noise is also influenced by the ground absorption, distance of source from receiver and road gradient. Hence it is necessary to apply corrections to the measured traffic noise levels. In this study a simple correction model has been developed for ground absorption, the distance and road gradient based on the field data. The method of calculating the ground absorption consists of identifying the locations which are totally or even partially absorbent in nature like backyards with gardens, paddy fields, tree density on either side of the roads and a mixture of absorbent and non-absorbent areas. Field measurements are taken from different locations with a varying percentage of soft ground cover. The correction value for ground absorption is estimated from the difference between the calculated noise levels and measured noise levels at varying percentages of soft ground cover. The correction value for distance is estimated from the difference between the calculated noise levels and measured noise levels at different horizontal and vertical distances over the hard ground surfaces. Similarly, the correction value for road gradient is calculated from the difference between the calculated noise levels and measured noise levels at different road gradients.