A new standard for the measurement of source terms for railway noise prediction models

A number of models for predicting railway noise have been, or are being developed that are all based on the approach devised in the EU Imagine project that finished in 2007. The CNOSSOS model for strategic noise mapping in the EU is amongst them. There is therefore a need to determine train- and track-specific source terms for these calculations. A new CEN standard is therefore being developed to guide these measurements. Most current railway noise measurement standards were developed for type testing purposes, such as EN ISO 3095, referred to by the European TSI legislation. Measurement of source terms for prediction models differs from type test measurements, particularly in their applicability to a vehicle fleet, to operational track conditions, and the requirement to determine sound power terms rather than sound pressure levels. The new standard sets out methods to characterise individual physical noise sources including rolling noise, traction noise, aerodynamic noise, impact, curving and braking noise. The standard must give guidance on how to derive each of the source sound power terms from sound pressure measurements. The rolling noise sound power is calculated from wheel/rail roughness spectra and transfer functions from roughness to vehicle and track sound powers. This paper gives an overview of the scope, key elements and considerations of the current draft standard. © INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering. All Rights Reserved.