Pass-by noise assessment of high speed units by means of acoustic measurements in a perimeter close to the train

Characterization of rolling stock from the perspective of exterior noise emission is typically carried out by following the technical procedures detailed in the international standard ISO 3095. Whilst this standard can be considered adequate for conventional rolling stock, the advent of very high speed railway transport has introduced a number of challenges in terms of the characterization of noise emission. The most relevant one is the multiplication of noise sources, with the substantial increase in aerodynamic noise emissions from particular zones in the train including: pantograph, pantograph recess, inter-coach gaps, front of train, connection cables, low-level turbulences,high level noise, etc.For example, high level noise hasa major influence on the effectiveness of mitigation measures such as noise barriersbecominga contributor to the environmental im-pactof the trainat very high speed.Therefore it is desirable to differentiate be-tween noise sources in order to inform whole-system designand ISO 3095 does notcurrentlyprovide an appropriate method for addressing this issue.This paper proposesan improved methodology for acoustic characterization that although more difficult than the procedures described in the standard ISO 3095, is not as difficult as acoustical analysis based on microphone arrays.