A case study on the effectiveness of acoustic performance and parallel-setting-up of a transparent standardized composite structure sound barrier

Sound barriers (SBs) are widely applied to decrease road traffic noise in urban viaducts. However, their insulation may be reduced when installed inappropriately. Previous studies on SBs in China focused on constructions with a single-uniform surface structure. In contrast, this study will focus on the effectiveness and parallel-setting-up of an SB with a standardized composite structure. Its surface consists of three insulation panels, one transparent and the others sound absorptive. The vertical-body-construction can be divided into stand columns, fully light-transparent-insulation panels, and multilayer-sound-absorptive-insulation panels with micro-perforated surfaces or metal-mesh-covers. Onsite application photographs of the SBs were collected to illustrate existing problems. First, applying the professional environmental noise software Cadna-A on a microcosmic view, the vertical sectional sound fields of the case barrier at a viaduct are simulated to demonstrate the effectiveness of these SBs. Then, the model is used on a macroscopic view to analyze the sound performance of the SB parallel-setting-up. We have obtained insight from an acoustic application suggesting that some onsite parallel SBs are poorly set-up in practical engineering or EIA reports, which render the mitigation measures less effective and result in expensive wastage. Finally, we suggest reasonable design guidelines for the parallel-setting-up of composite-structure SBs.