A novel design of traffic noise barriers is presented: barriers that have a jagged instead of the conventional straight top edge. Experimental, numerical, and analytical investigations show that noise barrier performance can be improved by making the top edge jagged. In many, but not all, cases the jagged edge improves insertion loss, by up to 6 dB. The most promising theoretical approach is to model the edge as a directive line source. Besides yielding predictions that agree favourably with measurements, the line source model reveals that the diffracted field behind a jagged edge barrier depends strongly on the receiver location, the portion of the edge on the most direct path between source and receiver, and the inclination of the straight barrier edge segments. Further, because the model is easy to apply, it is a promising and powerful tool for design of optimum edge profiles.
Get full access to this article
View all access options for this article.
References
1.
KurzeU. J., “Noise reduction by barriers”, J. Acoust. Soc. Am55, 504–518 (1974).
2.
WattsG. R., “Acoustic performance of a multiple-edge noise barrier profile at motorway sites”, Applied Acoustics47, 47–66 (1996).
3.
WattsG. R., and MorganP. A., “Acoustic performance on an interference type noise barrier profile”, Applied Acoustics49, 1–16 (1996).
4.
WattsG. R.CrombieD. H., and HothersallD. C., “Acoustic performance of new designs of traffic noise barriers: Full-scale tests”, J. Sound Vib.177, 289–305 (1994).
5.
HothersallD. C.CrombieD. H., and Chandler-WildeS. N., “The performance of T-profile and associated noise barriers”, Applied Acoustics32, 269–287 (1991).
6.
WassiliefC., “Improving the noise reduction of picket barriers”, J. Acoust. Soc. Am.84, 645–650 (1988).
7.
HutchinsD. A.JonesH. W., and RussellL. T., “Model studies of barrier performance in the presence of ground surfaces. Part I: Thin, perfectly-reflecting barriers”, J. Acoust. Soc. Am.751807–1816 (1984).
8.
HutchinsD. A.JonesH. W., and RussellL. T., “Model studies of barrier performance in the presence of ground surfaces. Part II: Different shapes”, J. Acoust. Soc. Am.75, 1817–1826 (1984).
9.
MayD. N., and OsmanM. M., “Highway noise barriers: New shapes”, J. Sound Vib.71, 73–101 (1980).
10.
WirtL. S., “The control of diffracted sound by means of thnadners (shaped noise barriers)”, Acustica42, 73–88 (1979).
11.
BaileyM. R., and BlackstockD. T., “Isolation of a negative-pressure pulse by means of diffraction”, in Advances in Nonlinear Acoustics: 13th ISNA, Bergen, Norway, 1993, edited by HobaekH. (World Scientific, Singapore, 1993), pp. 158–163.
12.
BaileyM. R., “Isolation of a Negative-Pressure Pulse and Studies of Irregular-Edge Diffraction”, MS thesis, The University of Texas at Austin, Austin, (1994).
13.
MenounouP.BaileyM. R., and BlackstockD. T., “Edge wave on axis behind an aperture or disk having a ragged edge”, J. Acoust. Soc. Am.107, 103–111 (2000).
14.
HoS. T.Busch-VishniacI. J., and BlackstockD. T.“Noise reduction by a barrier having a random edge profile”, J. Acoust. Soc. Am.101, 2669–2676 (1997).
15.
RosenbergE. J., “Continued Investigation of Noise Reduction by a Random Edge Barrier”, MS thesis, The University of Texas at Austin (1997).
16.
OhmW. S., “Numerical Simulation of Noise Reduction by a Jagged-Edge Barrier”, MS thesis, The University of Texas at Austin (1997).
17.
PierceA. D., “Acoustics: An Introduction to Its Physical Principles and Applications”, Acoustical Society of America, American Institute of Physics, New York (1989).
18.
MenounouP.Busch-VishniacI. J., and BlackstockD. T., “Directive Line Source Model: A new model for sound diffraction by half planes and wedges”, J. Acoust. Soc. Am.107, 2973–2985 (2000).
19.
MenounouP., “Theoretical Study for Diffraction by Straight and Ragged Edge Barriers”, Ph.D Dissertation, The University of Texas at Austin (1998).
CarslawH. S., “Diffraction of waves by a wedge of any angle”, Proc. Lond. Math. Soc.18, 1291–306 (1920).
22.
MacDonaldH. M., “A class of diffraction problems,”Proc. Lond. Math. Soc.14, 410–427 (1915).
23.
BowmanJ. J., and SeniorT. B.A., “Electromagnetic and Acoustic Scattering by Simple Shapes”, edited by BowmanJ. J.SeniorT. B.A., and UslenghiP. L. E., (North-Holland Publishing Company, Amsterdam, 1969).
24.
BowlbyW., “Synthesis of Highway Practice 181: In-Service Experience with Traffic Noise Barriers”, Transportation Research Board, National Research Council, National Academy Press, Washington, DC, 1992.
25.
Noise Guideline 1992, Texas Department of Transportation, Division of Highway Design, Austin, TX (1992).
26.
Structural Design Specifications for Noise Barriers, American Association of State Highway and Transportation Officials (AASHTO), Washington, D.C. (1989).
