Previous attempts to determine an accurate prediction for l10 noise levels arising from interrupted traffic flows have not been entirely successful. Either the prediction equations were too complex or the errors of prediction were too large. This work has attempted to extend these previous studies to identify more accurately the important variables governing the generation and propagation of noise from interrupted flows in urban streets in london and thereby reduce systematic and random errors of prediction. The first stage of this new study concentrated on establishing the effect on l10 noise levels of the traffic related variables by constraining inter-site differences in street layout and other propagation features. In the second stage of the study the propagation of noise from the road source was examined together with reflection effects from buildings and the influence of layout geometry. It was found that l10 was primarily determined by the total volume of traffic and the proportion of different classes of vehicles in the traffic stream. It was found necessary to introduce a three tier classification of the vehicle population rather than two as is common practice when calculating l10 levels from freely flowing traffic. The final prediction equation is expressed in terms of easily obtainable variables and is significantly more accurate than the present department of the environment method (calculation of road traffic noise) in predicting noise levels in interrupted traffic flow situations. (Author/publisher)
Samenvatting