International Journal of Occupational Hygiene 2011. 3(2):43-48.

Numerical Analysis of the Efficiency of Different Median Barrier Models in the Presence of a Plain Roadside Noise Barrier
Mohammad Reza Monazzam, Samaneh Momen Bellah Fard


Roadside noise barrier as the noise control solution is extensively applied to reduce noise pollution. Median barrier like roadside barriers can make insertion loss at the receiver's area making a shadow zone behind the screen. However, the performance of roadside barrier can be affected by erecting a median barrier. Mainly a median barrier is considered as an extra structure to decrease the cross median crashes at highways. The aim of this study was to investigate the effectiveness of some treatments such as absorbent material and diffusers on various median barriers shapes. A 2D boundary element method was used to analyze the designed median barrier effects. Application of grass on the top surface of median barriers with even cap was more effective than those median barriers that had uneven cap. Utilizing Primitive Root Diffuser (PRD) and Quadratic Residue Diffuser (QRD) on the stem surface of median barrier has high efficiency due to cancel outing multiple reflection effects between roadside barrier and median barrier by 2.2 to 2.7 dB (A), while no improvement could be seen at median barriers with QRD and PRD tops.  Finally, it can be stated that the performance of most median barriers were increased using the reactive surfaces on the stem sides of the barrier, while the top surface treatment was not very effective in this kind of screens.


Median barrier; Boundary element method; Absorbent material; Diffusive devices

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Menge CW. Slopped barriers for highway noise control. Inter-Noise 1978; 78, 509-512.

Crombie DH, Peplow AT, Chandler-Wild SN, Hothersall DC. Multiple road traffic noise barriers. Proc. I.O.A., Volume 13 Part 1, 27-34, 1991.

Hothersall DC. Modelling the performance of noise barriers. The mitigation of traffic noise in urban areas. Euro symposium 1992, 247-258.

Shima H, Watanabe T, Yokoi T, Mizuno K, Matsumoto K, Yamamoto M, Miyama T. Branched noise barriers. Inter-Noise, 1998; 403-306, Christchurch, New Zealand.

Monazzam MR. Lam YW. Performance of T-shape barriers with top surface covered with absorptive quadratic residue diffusers. App Acoust 2008; 69:93-109.

Naderzadeh M, Monazzam MR, Nassiri P, Fard SMB. Application of perforated sheets to improve the efficiency of reactive profiled noise. App Acoust 2011, 72, 393–398.

Monazzam, MR, Naderzadeh M, Nassiri P, Fard SMB. Performance of environmental T- shape noise barriers coated with primitive root diffusers. Arch Acoust 2010; 35(4): 565–578.

Monazzam MR, Fard SMB. Performance of passive and reactive profiled median barriers in traffic noise reduction. J Zhejiang Uni. Sci. A (Appl. Phys & Eng) 2011; 12(1):78-86.

Martin SJ, Hothersall DC. Numerical modeling of median road traffic noise barriers. J Sound Vib 2002; 251(4):671-681.

Monazzam MR. Nassiri P. Contribution of quadratic residue diffusers to efficiency of tilted profile parallel highway noise barriers. Iran J Environ Health Sci Eng 2009; 6(4), 271-284.

Monazzam, M.R., and Nassiri, P. Performance of profiled vertical reflective parallel noise barriers with quadratic residue diffusers. Int J Environ Res 2009; 3, 69-74.

Monzzam, M. R. and Samaneh M. B. Fard, Impacts of different median barrier shapes on a roadside environmental noise screen. Environ Eng Sci 2011; 28(6): 435-441.

Baulac M, Defrance J, Jean P. Optimisation with genetic algorithm of the acoustic performance of T-shaped noise barriers with a reactive top surface. App Acoust 2008; 69:332–42.

Watts, G.R., Crombie, D.H., Hothersall, D.C., Acoustic performance of new design of traffic noise barriers: Full scale tests. J Sound Vib 1994; 177(3); 289- 305.

Ishizuka T, Fujiwara K. Performance of noise barriers with various edge shapes and acoustical conditions. App Acoust 2004; 65, 125–141.

Delany ME, Bazely EN. Acoustical properties of fibrous absorbent material. App Acoust 1970; 3(2), 105–16.

Wu T, Cox TJ, Lam YW. A profiled structure with improved low frequency absorption. J Acoust Soc Am 2001; 110(6):3064–70.

Cheng WF, Ng CF. The acoustic performance of an inclined barrier for high-rise residents. J Sound Vib 2001; 242(2):295-308. [doi:10.1006/jsvi.2000. 3352]

BS EN 1793-3:1998, Road traffic noise reducing devices. Test method for determining the acoustic performance. Part 3, Normalized traffic noise spectrum.

Monazzam MR, Lam YW. Performance of profile single noise barriers covered with quadratic residue diffusers. Appl Acoust 2005; 66: 709–30.


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