Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit (2010) / Chapter Skim
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TCRP D-12 Final Report 12 2. LITERATURE REVIEW The goals of the literature review were to 1)
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TCRP D-12 Final Report 13 response relationships)
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TCRP D-12 Final Report 14 The acceleration weighting curves used in various standards are shown in Figure 1. The quantities shown in the figure are: • Wm (KB)
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TCRP D-12 Final Report 15 Figure 1: Acceleration Weighting Curves Figure 2: Weighting Curves in Terms of Velocity
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TCRP D-12 Final Report 16 Figure 3: Normalized Velocity Weighting Curves The commonality of the weighting curves raises the question as to how much difference the weighting curves make in evaluating typical train-induced ground vibration spectra. Several typical train vibration spectra are shown in Figure 4.
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TCRP D-12 Final Report 17 Table 4 shows that, except for the simulated very low-frequency spectrum, the variation between weighted and un-weighted levels after normalization is negligible (less than 0.5 dB)
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TCRP D-12 Final Report 18 Table 4: Weighted Acceleration Metrics for Representative Train Spectra Spectrum Velocity VdB1 Weighted Acceleration Levels, dB2 Wm Wk ANSI BS 6841 1. Rapid Transit Un-normalized 72.0 51.0 58.3 50.9 60.3 Normalization Factor 0.0 21.0 13.9 20.9 11.8 Normalized Value 72.0 72.0 72.2 71.8 72.0 Difference -- 0.0 0.2 -0.2 0.0 2.
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TCRP D-12 Final Report 19 Most RMS detectors used in sound and vibration analyzers perform an exponential running average of the RMS sound or vibration level. The exponential time weighting for the running average is defined as: 2/1 0 /)
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TCRP D-12 Final Report 20 Table 5: Comparison of v95 and Average Vibration Level for Typical Transit Vibration Levels Train Measured Vibration Levels, BART Train Passbys, VdB 0 m 3.8 m 7.6 m 11.4 m 15.2 m 22.9 m 30.5 m Train 1 71.8 68.5 69.9 64.4 70.6 68.3 66.4 Train 2 71.2 67.7 69.4 64.3 70.3 68.1 65.7 Train 3 71.2 67.9 69.5 64.2 70.2 68.0 65.8 Train 4 72.5 69.2 70.4 65.3 70.6 68.2 66.0 Train 5 71.0 67.8 69.3 63.9 69.9 67.5 65.4 Train 6 72.6 71.0 73.1 62.1 71.3 70.1 67.8 Train 7 72.5 71.0 73.1 61.9 71.1 69.8 67.5 Train 8 67.8 65.2 66.3 59.4 67.6 66.0 63.8 Train 9 73.0 71.9 73.2 58.0 69.6 68.7 67.5 Train 10 73.0 71.9 74.0 61.4 70.8 69.5 67.3 Train 11 72.9 71.1 73.0 63.4 71.8 70.6 68.2 Averages Decibel1 72.0 69.8 71.6 63.0 70.4 68.8 66.7 Linear2 71.9 69.6 71.3 62.8 70.4 68.7 66.6 Lv953 74.0 72.7 74.7 65.9 72.1 70.8 68.6 Difference4 2.0 2.9 3.1 2.9 1.7 2.0 1.9 1. Energy average of decibel values.
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TCRP D-12 Final Report 21 Figure 5: Example of Statistical Maximum Velocity (BART data at 7.6 m) Vibration Dose Value (VDV)
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TCRP D-12 Final Report 22 4 1 4 = ∑ i itotal VDVVDV It is important to note that the frequency weighting scheme used with Vibration Dose Values is the BS 6841(z)
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TCRP D-12 Final Report 23 Table 6: Standardized Frequency-Weighted Sound Levels Sound Level Weighting Source Description A ANSI 1.4-1983 (R2006) Nominal equal-loudness at low sound levels B ANSI 1.4-1983 (R2006)
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TCRP D-12 Final Report 24 Figure 6: Common Weighting Networks Used for Assessing Airborne Sound Impacts Some of the more relevant conclusions of the MSP expert panel include the following: • Loudness level contours (such as those of Stevens (13)
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TCRP D-12 Final Report 25 predictor of rattle, not of long-term annoyance. It has subsequently been shown empirically to function well as a predictor of the annoyance engendered by rattle.
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TCRP D-12 Final Report 26 It is difficult to directly compare the vibration limits adopted by different countries because many standards measure vibration differently. Figure 8 shows the approximate limits (in VdB)
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TCRP D-12 Final Report 27 Figure 8: National Limits for Rail Transit Vibration 2.4 Research on Human Response to Vibration A variety of laboratory and field studies of human response to vibration have been published. The research ranges from ride quality studies, to hand-arm vibration due to work tools, to whole body vibration.
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TCRP D-12 Final Report 28 experimentally derived perception thresholds are generally higher than those stated in ANSI S3.29 (4) particularly at frequencies below 20 Hz.
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TCRP D-12 Final Report 29 Figure 10: Equal Vibration Perception Contours Compared to Perception Threshold (Adapted from Bellman et al, 2004 (25)
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TCRP D-12 Final Report 30 2.4.2 Combined Effects of Broadband Noise and Ground-Borne Vibration The consensus of a small body of research on the combined annoyance of noise and vibration is that noise is more annoying when accompanied by vibration. For example, in an evaluation of noise and vibration near railways in Sweden, Öhrström and Skånberg (26)
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TCRP D-12 Final Report 31 frequent (>70 events/day) , occasional (30-70 events/day)
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TCRP D-12 Final Report 32 orthogonal directions over a 24-hour period. Train events were separated from the background vibration, and a number of different vibration metrics were calculated including the Vibration Dose Value, as well as overall levels using Wb and Wg weighting curves.
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TCRP D-12 Final Report 33 Figure 11: Annoyance Response of Survey Respondents Source: Klæboe et al.
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TCRP D-12 Final Report 34 A recent study (34) was commissioned by the Department for Environment Food and Rural Affairs (DEFRA)
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