Local impact assessment of urban traffic noise

Abstract

Traffic noise in urban areas causes annoyance and sleep disturbance. High noise levels may be reduced by various types of noise reduction measures, e.g. noise barriers or low-noise asphalt. The effectiveness of such measures can be determined by an impact assessment, in which the effects of traffic noise (annoyance, sleep disturbance) are assessed by combining noise exposure levels with exposure- response relations. The standard approach for an impact assessment is to use a standard calculation model for the noise levels and standard exposure- response relations reported in the literature. This approach is acceptable for large-scale noise impact assessments, for example for the entire EU. For traffic noise in a limited urban area, however, the standard approach may give inaccurate results, and a more detailed local impact assessment methodology is preferred. This means that use is made of an optimized noise model, based on measured local noise levels, and local exposure-response relations, based on local noise annoyance surveys. In this article, the local impact assessment methodology is worked out and applied to annoyance and sleep disturbance by road and rail traffic noise in an urban area in The Netherlands, with about 1000 inhabitants. Values of the day-evening-night noise level and the night noise level at the facades of dwellings are determined with an engineering noise model that is optimized for the local situation, based on local noise measurements. Local exposure- response relations are determined by combining the noise levels with results of an annoyance survey among 71 inhabitants, using the regression method with censored normal distributions developed by Miedema and coworkers. The impact is represented by values of the local prevalence of annoyance and sleep disturbance. Considerable deviations are found from standard predictions, i.e. values according to the standard approach. Possible explanations for the deviations are discussed, including the role of accumulation of road and rail traffic noise. Finally, the local impact assessment method is applied to future scenarios for the urban area, including measures aimed at reducing road and rail traffic noise.