In recent years, freeway and expressway construction projects in our country often adopt elevated engineering structures along many sections. With plain roads underneath, after completion of viaducts, the noises derived from traffic on plain roads underneath tend to make multiple reflections when they hit the bottom of the viaduct, making the volume of noises increased. Obviously having affected the living quality of the residents on both sides of the roads, these reflection noises have become the main complained issue in petitions concerning reflection noises. This project aims to identify the impact of reflection noises through simulation. The factors to be considered include the sound absorption rate underneath the viaduct, traffic load and speed underneath (or around both sides of) the viaduct, width of the viaduct, and the different impact on residents or passersby with different distances from the area underneath the viaduct. Through investigation, monitoring, simulation and analysis, this project plans to propose recommendations and improvement measures for reducing the noises underneath the viaducts in our country. Other than collecting and analyzing information on noise properties and improvement measures concerning the noises underneath the viaducts in advanced countries, such as Japan, and investigating and discussing about the noise situations underneath the viaducts in our country, the objectives of this project also include analyzing the noise situations underneath the viaducts in our country, proposing improvement measures, and coordinating with road competent authorities to discuss the proposed improvement measures on noises underneath the viaducts in our country.Results of the Research Project on Noise Control Solutions and Improvement Measures for Land Transportation System (Particularly Noises underneath Viaducts) include: 1. Collected and analyzed information on noise properties and improvement measures (including measuring and assessing methods and preventive measures) concerning the noises underneath the viaducts in advanced countries, such as Japan. 2. Investigated the noise situations underneath the viaducts in our countries (including collected and integrated research methods concerning noises underneath the viaducts adopted in foreign countries), convened 2 Expert Advisory Panel meetings, and analyzed the effect of sound-proof walls at 20 spots that are likely to be affected by noises underneath (or around both sides of) the viaducts in our country. 3. Established basic data on noises underneath (or around both sides of) the viaducts in our country and proposed improvement measures. The activities included field investigation of more than 6 spots (including environmental conditions, viaduct data, traffic flow and noises), noise simulation, and determination of the impact of noises. 4. Coordinated with road competent authorities to discuss the proposed improvement measures on noises underneath the viaducts in order to collect opinions from all circles on research methods, feasible preventive measures and improvement measures for noises underneath the viaducts in our country. We also appointed a specific person to compile the “Noise Control Records” and conduct related administrative works.

reflection noise