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OCTA I Santa Ana/Garden Grove Fixed Guideway Project <br />FNNoise and Vibration Technical Analysis Re-evaluation in Support of Minor Design Modifications <br />sufficient to cause strong, adverse reactions from the community. <br />Severe Impact: A significant percentage of people would be highly annoyed by the new noise. <br />Noise and Vibration Evaluation of Minor Design Modifications <br />INCREASE IN SPEED <br />The potential noise impacts associated with the proposed increase in the streetcar operational <br />speed was calculated using the methodology described in Tables 5-1 and 5-2 of the FTA Transit <br />Noise and Vibration Impact Assessment Manual (May 2006). <br />Changing the average speed from 35 to 45 mph would increase the hourly streetcar operation <br />noise levels by 2 dBA (see Attachment C). The change in speed would have no effect on the <br />warning horn, crossing, or operations and maintenance (O&M) noise levels. <br />CENTERLINE RE -ALIGNMENT (ALIGNMENT SHIFT) <br />This proposed modification would shift the railroad alignment within the PE ROW to the north as <br />compared to the originally -approved LPA alignment. Table C Comparison of the originally - <br />approved LPA and Proposed Modified Project Alignment Shift Noise Levels lists the distances <br />from the modeled receivers to the original LPA alignment and the distances to the currently <br />proposed alignment shift. Table C also lists the streetcar operation noise levels associated with <br />the original LPA and currently proposed streetcar alignments. Noise levels listed in Table C only <br />reflect the change in alignment not the change in speed discussed above. <br />Table C: Comparison of Originally -Approved LPA and Modified Project Alignment Shift <br />Noise Levels <br />Receiver <br />Land <br />Use <br />Cat. <br />Original Alignment <br />Distance to Track <br />Centerline (ft) <br />Proposed <br />Alignment Distance <br />to Track Centerline <br />(ft) <br />Original <br />Alignment <br />Streetcar <br />Operations <br />Noise Level <br />Proposed <br />Alignment <br />Streetcar <br />Operations <br />Noise Level <br />Change in <br />Streetcar <br />Operations <br />Noise Level <br />R1 <br />2 <br />72 <br />89 <br />51 <br />54 <br />3 <br />R2 <br />2 <br />79 <br />90 <br />50 <br />49 <br />-1 <br />R3 <br />2 <br />92 <br />92 <br />50 <br />50 <br />0 <br />R4 <br />1 2 <br />1 92 <br />92 <br />50 <br />50 <br />0 <br />R5 <br />2 <br />65 <br />55 <br />51 <br />52 <br />1 <br />R6 <br />2 <br />53 <br />49 <br />56 <br />56 <br />0 <br />R7 <br />2 <br />50 <br />37 <br />57 <br />62 <br />5 <br />R8 <br />3 <br />83 <br />92 <br />51 <br />51 <br />0 <br />R9 <br />3 <br />392 <br />401 <br />48 <br />48 <br />0 <br />R11 <br />3 <br />134 <br />134 <br />49 <br />49 <br />0 <br />R10 <br />1 2 <br />1 55 <br />1 55 <br />1 56 <br />1 56 <br />1 0 <br />R12 <br />2 <br />49 <br />49 <br />57 <br />57 <br />0 <br />R13 <br />2 <br />57 <br />60 <br />56 <br />56 <br />0 <br />R15 <br />2 <br />N/A <br />N/A <br />N/A <br />N/A <br />N/A <br />R14 <br />2 <br />110 <br />110 <br />53 <br />53 <br />0 <br />Source: URS (February 2012) and HDR (June 2016). <br />Note: The elevated tracks adjacent to receivers R1 and R7 increase the source level by 4 dBA. This was not <br />5 <br />