Improved Methods for In-situ Measurement Railway Noise Barrier Insertion Loss

Many countries which seek to understand the acoustic performance of railway noise barriers have established standards for the conduct of in-situ experiments. However, there are no universally acknowledged receiver positions for the evaluation of the barrier performance, a fact which may be leading to uncertainty over the noise reduction capabilities of available barriers. In terms of the descriptor of the barrier performance, the general recommendation is the A-weighted sound pressure level, although the latter is considered to underestimate low frequencies for railway noise barrier. Thus, in this study, the comparison of receiver positions and the descriptors among existing Chinese, ISO and European standards were investigated. Based upon a combination of diffraction theory and standards, a rearrangement of receiver positions and one-third-octave-band analysis were proposed. In addition, in line with improved methods, an in-situ measurement of insertion loss for a 1.5m high railway noise barrier was designed and conducted. The results of the experiment validate as effective and applicable the new receiver positions. These results also suggest that one-third-octave-band analysis is indispensable.