Abstract

The Netherlands has extensive legislation and regulations in place pertaining to air quality and noise. Mathematical models are used to implement this policy and to check whether the situation in the field actually complies with the standards. It is already difficult to accomplish this with the help of measurements alone and it will become impossible in future situations. The Ministry has drawn up policy to ensure that the results of measurements and calculations are more in agreement with each other.

To realise this, RIVM provides recommendations on how and where the mathematical models need to be improved with regard to managing and updating the models and which actions are needed to achieve this. Many parts of this study apply to the noise produced by road and railway traffic. When it comes to air quality, a number of aspects have already been managed more effectively.

In particular, it's important to ensure that the mathematical modelling instructions are managed and administered as transparently as possible. In addition, the data used as input for the modelling activities must be updated on a regular basis. The scope within which the mathematical modelling methods can be used effectively also needs to be clearly defined and a procedure must also be in place for using alternative methods in situations that fall outside this scope of modelling. With regard to the measurements, the method used to determine the average annual noise exposure, must be defined more clearly. In addition, a clear description needs to be provided indicating when differences between the results of measurements and modelling activities are significant. Finally, it is important that the responsible authorities provide answers, correctly, unambiguously and quickly, to questions from residents in the affected area.

The proposed improvements are important as a certain level of mistrust exists with regard to the use of mathematical models, particularly in situations where the standards and the results of modelling activities do not correspond very well with the levels of nuisance actually experienced. In such cases, measurements are often carried out, but these do not always provide a satisfactory answer.