In order to avoid or minimise noise conflicts, COWI evaluates noise from industry according to national guidelines by performing measurements and/or calculations. In special situations, low frequency noise is also evaluated with its own specific limits and methods.
Noise calculations
It can often be most beneficial to predict noise levels by carefully selected source data and propagation calculations. In this way, disturbances from other noise sources are avoided, and the results are not affected by weather conditions.
Where this method is possible, COWI collects the necessary input data for a noise prediction model using commercially available software like SoundPLAN, IMMI or CadnaA. The primary noise sources together with topographical data, such as terrain elevation and buildings, are entered into the model. The resulting noise map and single point calculations document noise levels under weather conditions according to the guidelines.
Noise measurements
If a prediction based on calculation is not possible, perhaps because data defining the noise sources is unavailable, COWI performs a noise measurement at the receiver's. Measurements often take place at night when lower noise limits apply and when disturbances from other noise sources such as road traffic are at a minimum. COWI records wind direction and speed, corrects for the influence of background noise, excludes extraneous noise (such as road traffic noise) and assesses whether a penalty for tone or impulse noise should be included in the overall calculation of noise levels.
Noise mitigation measures
Where noise limits are exceeded, we identify the most feasible noise mitigation measures that can bring noise levels down to an acceptable level according to guidelines or the environmental approval.
Evaluating noise levels In development situations, the final approval of local authority plans can often be dependent on a ruling on noise levels. In this case, COWI evaluates if noise from industry will be a problem before a new residential area is built. In other instances, residents may complain to their local authorities in respect of noise from an existing industrial activity. In both cases, COWI carries out measurements or calculations and issues the final verdict to the local authority.
