Prediction of freeway noise levels (L10): an evaluation of the U.K. dept of the environment procedure

The United Kingdom Department of the Environment has published a method of predicting road traffic noise levels (l 10) from traffic parameters and roadway geometry. To test this prediction procedure, l 10 (half hour) and l 10 (18 hour) were measured and predicted at 17 sites near the South East Freeway, Brisbane. Road traffic volumes used in the predictions were those measured simultaneously with the noise levels. Predicted and measured l 10 have been plotted for each half hour of the day at the 17 sites. The study included locations beside cut, fill and at grade sections of the freeway, often with sites of very complex acoustical geometry. Agreement between the measured and predicted levels was good for all site conditions. (Over all sites the mean difference in l 10 (half hour) was 0.7 Db(a), over prediction, with standard deviation of the differences 1.7 Db(a).) The method can be recommended for adoption where prediction of l 10 noise levels is required, at least for the range of traffic and geometry conditions covered in this study. A relationship between l eq and l 10 has been given which allows estimates of l eq to be predicted by the doe procedure (a).