Methods For Calculating LAFmax Using The Nordic Prediction Method, Nord 2000 And Cnossos-EU

摘要

In Sweden the use of maximum a-weighted sound level (LA_(Fmax)), in combination with equivalent a-weighted sound level over 24h (L_(Aeq24h)), has been used for noise regulation for many years. The regulation was turned into legislation in 2015 for new housing development plans. The maximum level gives a good indication of sleep disturbance for residents in exposed dwellings, especially if combined with number of loud passages or events. In areas with little traffic the equivalent level can be very low, whereas the maximum level just depends on an individual vehicle rather than on the number of vehicles. The Swedish legislation defines maximum noise level as "the loudest vehicle, with time weighting 'Fast', calculated as a free field value". When calculating noise levels from road or rail traffic, there is no knowledge of individual vehicle properties. In the prediction methods used in Sweden, the calculation of maximum level is therefore based on statistical data such as the standard deviation of measured sound levels for each vehicle type at a certain speed. In the current paper some different methods to calculate maximum noise levels are presented, using Nordic methods as well as the common Cnossos-EU method, as well as their impact on results.