An investigation on the noise reduction performance of profiled rigid median barriers at highways.

Median barriers as a portion of a divided highway are provided to minimize the cross-median crashes. Moreover, median barriers similar to roadside noise barriers could protect people from transportation noise. Thus, there is a need to investigate various median barrier models to identify changes of insertion loss over a simple rigid barrier. In order to estimate the acoustical influence of median barrier's profile in the shadow zone, different median barrier models are presented and their insertion losses are calculated over a frequency range from 50 to 4000 Hz using a two-dimensional boundary element method. The present investigation has clearly revealed that among the profiled median barriers, T-shape, Y-shape, and L-shape provide better performance than that of the other shapes. It is also found that among inclined barriers, V-shape barrier significantly presents higher values of attenuation. Based on the calculation of different geometrics, it has been shown that a further 2 dB (A) in efficiency could be obtained by a better design of the median barrier which is labeled model "L."