Design Consideration of a Noise Barrier

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From the guidelines of EPD,the major function of noise barrier is to eliminate the excessive noise generated by vehicles. Noise barriers are considered as the most reasonable and efficient noise mitigation measures. Many factors need to consider in design of noise barrier. They are Acoustical Design Consideration, Transmission Loss of Various Barrier Materials, in Noise Barrier Performance due to Holes, Slits or Gap, Barrier Shape ,Choice of Material ,barrier materials
,Earth Berms and Retaining Structures and Non-acoustical Consideration. This report first to introduce the eight considerations listed on above and give the case study of noise barrier in Hong Kong to make a analysis to know is it excellent or not.

Acoustical Design Consideration

Acoustical performance is related to material,location,dimensions and shape of noise barrier. Normally,noise from the road traffic mainly reflected by noise barrier toward the source and some of the noise are absorbed by the barrier or diffracted at the top edge of barrier. The diffraction of the noise mainly depends on the location, shape and dimensions of barriers. The lower portion of absorptive materials should at least two to three meters. It ensure the materials would absorb most of the noise energy.

Transmission loss of various barrier materials

It is acknowledged that all materials permit sound energy to pass through, it depends on the material and frequency of sound.”Transmission Loss” is the attenuation of sound passing through a material. For acoustical purposes , the materials used for barrier between noise source and noise receiver as long as it has a TL of at least 10dB greater than the desire noise reduction. It ensures that the only nise path to be considered in acousti...

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...ge to the ecosystem and environmental like the phenomenon shows in case II. Indeed, case II is a failure design.

(Magazine of HKBWS)
To sum up , compare with case I and case II ,choice of material is a important part for design consideration. It is necessary to understand the geographical conditions and make a correct choice of materials. For case II, non-transparent materials should be used like concrete , that reduce the chance of the birds collide to the barrier. In the future , government can take case I as the role model for designing noise barrier. Since case I can construct it self with natural growth of grass, it is environmental friendly. Last but not least, it is necessary to base on the eight design consideration of EPD guideline.

Works Cited

http://www.epd.gov.hk/epd/english/environmentinhk/noise/guide_ref/design_barriers_content2.html

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