An L (sub eq) (24 hour) type noise model is required for use in New Zealand so that L (sub eq) (24 hour), as used in traffic noise guidelines, can be predicted directly. An evaluation of models which predict noise levels from road traffic in terms of L (sub eq) (24 hour) was undertaken by comparing predicted levels with noise levels measured at 20 sites. These sites included motorways, highways, urban arterials and urban streets. Three main L (sub eq) models were evaluated: the Nordic, the FHWA, and the CETUR models. In addition, the CRTN model was included as an L (sub eq) type model with both UK and New Zealand road surface corrections, and a simplified version of CETUR. It was found that the Nordic model was able to correctly predict noise levels within 2 dBA at all 20 sites. CRTN was able to predict L (sub eq) (24 hour) to the same level of accuracy as L (sub 10) (18 hour), and predicted 15 sites. The CETUR and FHWA models were less successful, with only 65 percent successful predictions. The L (sub eq) models could give strongly indicative predictions (80 percent successful) for traffic flows as low as 10 vehicles per hour or less. It was also found that accurate account needs to be taken of the road surfaces' effects on noise levels for accurate prediction. (A)
Abstract