Noise reduction effect evaluation of LOS sound barriers

In order to evaluate the application effect of line of sight (LOS) sound barrier in the areas with less excessive noise level and fewer households, the noise monitoring and traffic noise model (TNM) analysis at the highway I-465 with LOS sound barrier in Indiana, USA have been done. The influences of pavement type, vehicle speed, traffic volume, noise reduction coefficient, height and extended length of sound barrier on noise reduction level of LOS sound barrier were analyzed, the application effect of LOS sound barrier was evaluated, and the key design parameters were proposed. Analysis result shows that LOS sound barrier can be applied in the areas with less excessive noise level and fewer households. The influence of pavement type on noise reduction is significant. If cement concrete pavement (CCP) is replaced by dense-graded asphalt concrete pavement (DGACP) or open-graded asphalt concrete pavement (OGACP), the range and effective rate of noise reduction can be improved significantly. It is not effective to reduce traffic noise by lowering speed limits, therefore, it is not recommended. For designing LOS sound barrier, the design noise reduction range should be above 6.7 dBA, the minimum barrier height should be tall enough to block the view of large vehicle and the maximum barrier height is 6.6 m, the optimum height of LOS sound barrier in design year should be determined by traffic noise model analysis. ©, 2015, Chang'an University. All right reserved.