Measured Analysis of Noise Reduction Effect for Urban Rapid Rail Transit Viaducts
[Objective]To reduce the impact of elevated lines in urban rapid rail transit on environmental noise,multi-ple noise-reduction measures such as near-track sound barriers and ballast bed sound-absorbing panels are adopted.On-site measurements and analyses should combine with on-site operat-ing conditions to verify the effectiveness of trackside noise re-duction measures in reducing environmental noise.[Method]In the case study of the already operating Line S1 of Wenzhou Urban Rapid Rail Transit,the environmental noise in the via-duct section of this line is measured on site.The noise reduc-tion effects of near-track sound barriers and ballast bed sound-absorbing panels for the environmental noise under different train running speeds are compared and analyzed,and the influ-ence characteristics of different noise reduction measures on the viaduct section noise are explored.[Result & Conclusion]The near-track sound barrier reduces the maximum instantane-ous A-weighted time-domain sound pressure level(hereinafter abbreviated as"A-weighted level")on the viaduct inner and outer sides by approximately 20 to 21 dB(A).At the position 7.5 meters away from the track center line and 7.5 meters a-bove the rail surface,the A-weighted level in the 500 Hz and 800-1 000 Hz frequency bands are respectively reduced by 6 to 11 dB(A)and 17 to 21 dB(A).The ballast bed sound-ab-sorbing panels can further reduce the trackside noise on and outside the viaduct.Compared with the working conditions where only the near-track sound barriers are installed,when u-sing the sound-absorbing panels,the maximum instantaneous A-weighted level on the viaduct is further reduced by 14 to 17 dB(A)with the same train running speed,and the A-weighted level is reduced by 7 to 8 dB(A)and 5 to 7 dB(A)respec-tively for the noise in the 500 Hz and 800-1 000 Hz frequency bands at the same measuring point outside the viaduct.
万方数据
维普
