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0� OCTA I Santa Ana/Garden Grove Fixed Guideway Project <br />Noise and Vibration Technical Analysis Re-evaluation in Support of Minor Design Modifications <br />Impact of Proposed Minor Modifications/Engineering Refinements <br />INCREASE IN SPEED <br />Changes in streetcar operational vibration levels due to increased speeds were calculated using <br />the methodology described in Chapter 10 of the FTA Transit Noise and Vibration Impact <br />Assessment Manual (May 2006). <br />The original vibration assessment (URS 2012) used a maximum vehicle speed of 40 mph. <br />Changing the average speed from 40 to 45 mph would increase the streetcar vibration levels by <br />1 VdB. The vibration calculations used in this analysis are provided in Attachment C. <br />ALIGNMENT SHIFT <br />As discussed previously, the proposed modification would shift the railroad alignment within the <br />PE ROW to the north. Table K lists the distances from the modeled receivers to the originally - <br />approved LPA alignment and the distances to the proposed alignment. Table K also lists the <br />streetcar operation vibration levels associated with the original and proposed streetcar <br />alignments. The vibration levels listed in Table K only reflect the change in centerline not the <br />change in speed discussed above. <br />Table K: Comparison of Originally -Approved LPA and Proposed Modified Alignment Shift <br />Streetcar Vibration Levels <br />NSA <br />Rec. <br />Land Use <br />Cat. <br />Original <br />Alignment <br />Distance to Track <br />Centerline (ft) <br />Proposed <br />Alignment <br />Distance to <br />Track <br />Centerline (ft) <br />Original <br />Alignment <br />Streetcar <br />Operations <br />Vibration Level <br />(VdB) <br />Proposed <br />Alignment <br />Streetcar <br />Operations <br />Vibration Level <br />(VdB) <br />Change in <br />Streetcar <br />Operations <br />Vibration <br />Level (VdB) <br />R1 <br />2 <br />72 <br />89 <br />68 <br />57 <br />-11 <br />1 <br />R2 <br />2 <br />79 <br />90 <br />67 <br />67 <br />0 <br />R3 <br />2 <br />92 <br />92 <br />67 <br />67 <br />0 <br />2 <br />R4 <br />2 <br />92 <br />92 <br />67 <br />67 <br />0 <br />R5 <br />2 <br />65 <br />55 <br />68 <br />69 <br />1 <br />3 <br />R6 <br />2 <br />53 <br />49 <br />70 <br />70 <br />0 <br />R7 <br />2 <br />50 <br />37 <br />70 <br />62 <br />-8 <br />R8 <br />3 <br />83 <br />92 <br />66 <br />65 <br />-1 <br />4 <br />R9 <br />3 <br />392 <br />401 <br />58 <br />58 <br />0 <br />5 <br />R11 <br />3 <br />134 <br />134 <br />62 <br />62 <br />0 <br />6 <br />R10 <br />2 <br />55 <br />55 <br />70 <br />70 <br />0 <br />7 <br />R12 <br />2 <br />49 <br />49 <br />70 <br />70 <br />0 <br />8 <br />R13 <br />2 <br />57 <br />60 <br />69 <br />69 <br />0 <br />9 <br />R15 <br />2 <br />N/A <br />N/A <br />65 <br />65 <br />0 <br />10 <br />R14 <br />2 <br />110 <br />110 <br />64 <br />64 <br />0 <br />Source: URS (February 2012) and HDR (June 2016). <br />Note: The elevated tracks adjacent to receivers R1 and R7 decrease the source vibration level by 10 VdB. This was <br />not accounted for in the original noise and vibration analysis. <br />11 <br />