Population exposure to road traffic noise: Experimental results from varying exposure estimation approaches

This paper assesses four methods for estimating population exposure to road traffic noise within the terms of the strategic noise mapping process laid down in the Environmental Noise Directive (END). Employing a case study in central Dublin, Ireland, the methods - MAX, MIN, VBEB/CNOSSOS and AVE - are tested utilising the Lden and Lnight indicators. The study first investigates the extent to which exposure estimates may vary depending on the method utilised while controlling for the noise calculation method. Second, it investigates how estimates of exposure vary depending on the calculation method used; in this case, CRTN and NMPB. The results show that controlling for noise calculation method and employing the same input data, estimations of population exposure differ substantially depending on the exposure method employed. Furthermore, the potential variability in estimated night-time exposure and the potential for under or over-estimation of the health effects of environmental noise on a given population when different methods are utilised is clearly demonstrated. The results also show that the method of noise calculation employed has an effect on estimated exposure, particularly for Lden measures. Values for Lnight were found to be very similar regardless of the calculation method employed. The results therefore suggest that it is the exposure estimation method rather than the noise calculation method which has the greatest effect on population exposure estimation and should therefore be of greatest concern for understanding population health impacts and for achieving consistent results.