European Committee for Standardization

Railway applications - Track - Noise barriers and related devices acting on airborne sound propagation - Test method for determining the acoustic performance - Part 7: Extrinsic characteristics - In situ values of insertion loss
 N CEN/TS 16272-7

Annotation

This Technical Specification specifies methods for the determination of insertion loss of outdoor noise barriers intended to shield railway noise. It specifies detailed procedures for in situ measurement of barrier insertion loss including microphone positions, source conditions and acoustic environments of the measurement sites.

This Technical Specification allows one to measure the insertion loss of a given noise barrier at a given site including given meteorological conditions. It does not make it possible to compare insertion loss values of an equivalent barrier at a different site. It can be used for comparing insertion loss values of different types of barriers at the same site under given meteorological conditions by the “direct method”.

This Technical Specification gives a method for determining insertion loss:

a) from the level difference before and after the installation of noise barriers (the “direct method”);

b) when the direct method is not applicable, because a barrier has already been installed, using an "indirect method" to estimate the sound pressure levels before installation of the barrier by measurement at another site which has been judged to be equivalent.

For equivalent sites, a close match is required in source characteristics, microphone locations, terrain profiles ground surface characteristics, surrounding artificial structures and meteorological conditions.

This Technical Specification prescribes principles for ensuring that sufficiently equivalent conditions are maintained between “before” and “after” cases to permit certain, reliable and repeatable determination of barrier insertion loss.