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Pearson Place 2nd Addition Traffic Noise Assessment <br />Table 2.7 Predicted Level RE NAC-2 Standards with a 12-Foot Barrier <br />L10 LEVELS L50 LEVELS <br />Receiver AM - 70 PM - 70 Receiver AM - 65 PM - 65 <br />H1W -8 -7 H1W -9 -6 <br />H2W -7 -5 H2W -8 -5 <br />H3W -6 -4 H3W -7 -4 <br />H3N -5 -4 H3N -7 -4 <br />H1E -8 -7 H1E -9 -6 <br />H2E -7 -5 H2E -7 -5 <br />H3E -5 -4 H3E -6 -4 <br />From Table 2.7 it can be seen that the L10 and L50 levels at all receptor sites can be brought into <br />compliance with state noise standards if the 30 dBA outdoor -to -indoor attenuation can be met. <br />Without detailed drawings of the building facades exposed to traffic noise, it is not possible to determine <br />the specific type of wall and glazing needed to comply with the state noise standards. An example of the <br />type of analysis required to ensure that the required 30 dBA attenuation can be made is presented in <br />Table 2.8 below. The composite STC is based upon the acoustical energy transmitted through each wall <br />component. <br />Table 2.8 Example Determination of Net Wall STC <br />,all with Patio Door STC AREA AREA <br />(S.F.) <br />Wall 42 75 82.50 <br />Windows 30 45 37.50 <br />TOTAL 120 100.001 <br />COMPOSITE STC 34 <br />Traffic adjustment -3 <br />Net STC 31 <br />Wall with Windows and Door STC AREA AREA <br />(S.F.) <br />Wall 42 60 50.00 <br />Windows 35 40 33.33 <br />Door 28 20 16.67 <br />TOTAL 120 100.001 <br />COMPOSITE STC 33 <br />Traffic adjustment -3 <br />Net STC 30 <br />David Braslau Associates, Inc. Page 10 <br />