Abstract
This paper presents development of a hood to mitigate penetration of noise accompanied by passages of the ultra-high-speed trains that has higher mitigation performance than the conventional upright noise walls. First, through on-site measurements for a pioneering type hood, it was found that air blown out from the openings such as gaps, slits, or structural joints had a significant effect on the noise level, and thus needed to be prevented. After the improvement on the openings, a hood of a segment frame structure that withstands the aerodynamic pressure fluctuation caused by the train passages is proposed. During the development, the future possible practical advantages of the hoods were also carefully considered, such factors as simpler construction and the easier maintenance. After several laboratory tests to confirm the noise mitigating performance of the local parts of the hood were conducted and the detailed structures were determined, a hood was experimentally constructed on the Yamanashi test line. Through the field measurements with this hood to investigate its effectiveness, it was finally confirmed that the noise level measured outside the hood was maintained low enough to satisfy the noise standard for the conventional high-speed rails targeted.
