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<br />4.0 Noise Barrier East of Hwy 10 <br /> <br />As part of the noise exemption request for 1-694 between 1-35E and I-35W, a noise barrier <br />along 1-694 was previously evaluated and detennined not to be cost effective. A new noise <br />barrier was analyzed to detemline if homes north of Briar Knoll Drive would receive any <br />acoustic benefits. <br /> <br />Both 20' and 10' noise barriers were analyzed at this location shielding receptors K-M. If <br />these receptors achieve a substantial reduction in noise (>5dBA), then they would be <br />analyzed to determine cost effectiveness. Figures 10 and 11 detail noise level attenuation and <br />a cost effectiveness analysis for receptors K-M located on the east side of Highway 10. <br /> <br /> <br />K 1 63.6 59.8 <5 <br />L 1 66.1 60.8 5.3 <br />M 2 66.9 60.3 6.6 <br /> Total Attenuation <br /> <br />Total Length of <br />Barrier :984' <br /> <br />Cost of 20' Barrier (@$15/sq.ft) ;$295,200/18.5 decibel reduction <br /> <br />o <br />5.3 <br />13.2 <br />18.5 <br /> <br />$15,597 <br /> <br />Figure 10, Noise Barrier Attenuation Analysis of20' Barrier <br /> <br /> <br />K <br />L <br />M <br /> <br /> 63.6 62.6 <5 <br /> 66.1 64.7 <5 <br />2 66.9 64.3 <5 <br /> Total Attenuation <br /> <br />o <br />o <br /> <br />o <br />o <br /> <br />NA <br /> <br />Total Length of <br />Barrier :984' <br /> <br />Cost of 20' Barrier (@S15/sq.ft);S147,600/0 decibel reduction <br /> <br />Figure 11, Noise Barrier Attenuation Analysis of 10' Barrier <br /> <br />A 20' noise barrier to the north of Briar Knoll Drive does create acoustic benefits greater <br />than 5dB. However the cost effectiveness ratio of $15,587 for a 20' barrier does not meet the <br />MnDOT criteria of$3,250 and is therefore not cost effective. <br /> <br />For a 10' barrier in the same location, there is not enough attenuation provided at any of the <br />receptors to make the barrier acoustically effective. Therefore, a 10' noise barrier is not cost <br />effective. <br /> <br />Noise Barrier Analysis <br />Highway 10 <br /> <br />Page 10 <br />