Traffic noise annoyance in a city or residential area is commonly assessed by first calculating noise levels with a standard calculation model and next applying standard relations for noise annoyance. Locally large deviations may occur from such predictions. In a residential area in Vught (NB) the deviations from standard predictions have been quantified by local measurement of both noise levels and noise annoyance.
The result of the study illustrates the importance of local experimental noise investigations in residential areas with busy roads and railroads. The approach followed consists of a combination of noise measurement, noise modeling, and detailed questionnaires for inhabitants about noise annoyance and sleep disturbance by traffic noise. Analysis of the questionnaires provides information about the detailed (partial) causes of noise annoyance and sleep disturbance, such as high noise levels of freight trains at night or vibrations inside dwellings caused by passing trucks. With this new TNO method, municipalities can accurately analyze local noise problems and assess noise reduction measures.
The study in Vught was carried out in 2013 in a residential area with about 1000 inhabitants. Noise levels were recorded during one week at 35 locations in the area, using an advanced network of microphones. Noise levels at all dwellings in the area were determined afterwards by combining the results of the noise measurement with model calculations. During the noise measurement week, noise annoyance and sleep disturbance were determined by having 35 inhabitants recording daily annoyance scores for road and rail traffic noise. 'Annoyance moments' were also recorded by inhabitants, such as the pass by of a freight train at night. In addition, 71 inhabitants have completed an extensive questionnaire about their yearly average noise annoyance and sleep disturbance, as well as various possible factors of influence such as facade insulation and characteristics of the noise such as high tones, low tones, and noise variations.
Local noise annoyance in the residential area in Vught has been assessed by combining the annoyance scores from the questionnaires with the noise levels on the dwellings. Based in this knowledge of local noise annoyance, it has been calculated that from the total number of about 1000 inhabitants of the area there are 350 inhabitants (35%) with high annoyance (or severe annoyance) by rail traffic noise and 340 inhabitants (34%) with high annoyance by road traffic noise. With a standard prediction, that is with a prediction based on a standard noise calculation and standard relation for noise annoyance, one finds only 70 inhabitants (7%) with high annoyance by rail traffic noise and 130 inhabitants (13%) with high annoyance by road traffic noise. Thus, at this location the number of people with high noise annoyance is underestimated by the standard method by a factor of about 4. The results of the study have also been used to estimate the effect of noise reduction measures.