Laserfiche WebLink
OCTA I Santa Ana/Garden Grove Fixed Guideway Project <br />FNNoise and Vibration Technical Addendum <br />Table I: 60 Percent Design Noise Levels — After Vehicle Audible Warning Exemption <br />Mitigation <br />NSA <br />Rec. <br />Land <br />Use <br />Cat. <br />Existing <br />Noise Level <br />(d BA) <br />Predicted Project Only Noise Level <br />Ldn or Lday (d BA) <br />Impact <br />Overall <br />Streetcar Audible Project <br />Ops Warning Crossing O&M Noise <br />3 <br />R7 <br />2 <br />50 <br />64 <br />N/A N/A N/A <br />64 <br />Severe Impact <br />6 <br />R10 <br />2 <br />53 <br />57 <br />0 51 N/A <br />58 <br />Moderate Impact <br />7 <br />R12 <br />2 <br />50 <br />58 <br />0 49 N/A <br />59 <br />Severe Impact <br />8 <br />R13 <br />2 <br />55 <br />57 <br />0 44 N/A <br />57 <br />Moderate Impact <br />10 <br />R14 <br />2 <br />58 <br />56 <br />N/A N/A 63 <br />64 <br />Severe Impact <br />Source: URS (February 2012) and HDR (February 2017). <br />Table J lists the combined noise levels after implementing wayside barriers and the vehicle <br />audible warning exemption. As shown, all severely impacted receivers are reduced to moderate <br />or no impact after the implementation of proposed mitigation. Eliminating the vehicle audible <br />warning at receptors R10 and R13 would reduce the noise impact from severe to moderate. <br />Therefore, no barriers are recommended at those locations. <br />Table J: Summary of Noise Impacts for 60 Percent Design — With Noise Attenuation <br />Measures <br />NSA <br />Rec. <br />Land <br />Use <br />Cat. <br />Existing <br />Noise Level <br />(d BA) <br />Predicted Project Only Noise Level <br />Ldn or Lday (d BA) <br />Impact <br />Overall <br />Streetcar Audible Project <br />Ops Warning Crossing O&M Noise <br />3 <br />R7 <br />2 <br />50 <br />59 <br />N/A N/A N/A <br />59 <br />Moderate Impact <br />6 <br />R10 <br />2 <br />53 <br />57 <br />0 51 N/A <br />58 <br />Moderate Impact <br />7 <br />R12 <br />2 <br />50 <br />53 <br />0 49 N/A <br />55 <br />Moderate Impact <br />8 <br />R13 <br />2 <br />55 <br />57 <br />0 44 N/A <br />57 <br />Moderate Impact <br />10 <br />R14 <br />2 <br />58 <br />53 <br />N/A N/A 59 <br />60 <br />Moderate Impact <br />Source: URS (February 2012) and HDR (February 2017). <br />Streetcar Vibration Analysis <br />The proposed minor modifications described in Table A could affect the vibration levels <br />previously predicted and documented in the June 2016 Noise and Vibration memorandum. A <br />vibration analysis was conducted that provides a comparison of the findings associated with the <br />30% design and with the 60% design. The following presents the results of this analysis. <br />Evaluation of Proposed Minor Project Modifications <br />DECREASE IN SPEED <br />Reducing the maximum speed within the PE ROW from 45 mph to 44 mph would have no effect <br />on the streetcar vibration levels. <br />11 <br />