Clarifications And Refinements To Squeal Noise In CNOSSOS

The common European method for environmental noise computations [1], to which we refer here as CNOSSOS, incorporates a description of curve squeal noise that needs clarification and refinement on a few aspects. Firstly, there is a (possibly) ambiguous formulation, as it features both an "appropriate description" and a "simple approach" for curve squeal. The text needs to clarify which of these formulations is to be used in which case. Secondly, the curve radius that is generally associated with squeal noise of tram systems is much smaller than the two curvature classes declared in CNOSSOS. Trams do not tend to squeal in curves with radii over 200 metres. Thirdly, the track length restriction, stating that squeal in sections shorter than 50 m can be ignored, implies that short turnouts (of switches) as well as tight tramway curves, both of which are likely to cause severe squeal, would be excluded. Finally, the expression 'branch-outs of points' needs to become more descriptive. This paper discusses the issues with the current model description and substantiates the modifications that are needed in the formal method description. In the course of 2019 it will be become clear if the proposed modifications to CNOSSOS will be accepted.