Enhancing the Dutch engineering calculation method.

Abstract

With the advent of new legislation, we have taken the opportunity to take a serious look at the Dutch national calculation method. This method, which is similar to ISO9613-2, needed enhancements to allow for the increasingly complex world outside. Objects like leaning barriers or diffracting elements on barriers are seen more and more. The 3D datasets that are available for noise models are much more complex compared to the time, many years ago, when these calculation methods were conceived. To allow for these situations we have enhanced our method. Reflections can now occur in 3D. This allows for leaning barriers. We take the size of objects into account to determine the fraction of noise reflected. Based on the CNOSSOS implementation a direction dependent meteorological correction is now used. Methods to account for diffracting elements in the ground and on barriers have been developed. The result is a method which is more robust. Many of these enhancements could also be used in other methods like CNOSSOS or other engineering calculation methods. In this presentation I will show you how these enhancements have improved our method and can be used to produce better noise maps and calculate more accurate noise levels.