Acoustic performance of a semi-closed noise barrier installed on a high-speed railway bridge: Measurement and analysis considering actual service conditions

Abstract Noise barriers are regarded as the most efficient way to mitigate high-speed railway (HSR) noise. To enhance their performance, the present paper introduces a novel type of noise barrier, namely a semi-closed noise barrier (SCNB). The service conditions of the SCNB are much more complicated than those of a traditional vertical barrier because of train draft pressure and vibration waves transmitted from the bridge deck. Although these issues could worsen the acoustic performance of the SCNB, they are yet to be studied in depth. In this study, the acoustic performance of the SCNB considering actual service conditions was investigated based on field measurements and numerical simulations. Special attention was focused on the noise reduction effect and the noise propagation pathways. The results show that the studied SCNB can perform better than the existing 3.15-m-high vertical noise barriers considering actual service conditions, with an additional attenuation of close to 6 dB(A). The structural noise associated with the SCNB vibrations contributes little to the overall noise, and the transmitted noise is the main acoustic source. A 1.0-mm-wide and 2.0-m-long slit between neighboring element panels can appear in the SCNB because of the train draft pressure and vibration waves transmitted from the bridge deck. The developed prediction method is fully adequate for checking the acoustic performance of the SCNB considering its actual service state. Results of the numerical analyses are quantitatively stated for the purpose of durability evaluation of the SCNB on acoustic performance.