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From page 47... ... TCRP D-12 Final Report 44 5. FIELD MEASUREMENTS 5.1 Measurement Overview The overall goal of the field measurements was to estimate the exposure of each survey respondent to ground-borne vibration and noise using a wide variety of exposure metrics. Read the entire page →
From page 48... ... TCRP D-12 Final Report 45 6. Perpendicular Measurements: At least one measurement series was performed at various distances along a perpendicular to the alignment. Read the entire page →
From page 49... ... TCRP D-12 Final Report 46 the week prior to the scheduled visit. Cooperation was generally very good. Read the entire page →
From page 50... ... TCRP D-12 Final Report 47 5.3 Field Measurement Procedures 5.3.1 Instrumentation All data collected in the field was recorded using Rion Model DA-20, four-channel digital recorders. The DA-20 systems record data as WAV files on compact flash cards. Read the entire page →
From page 51... ... TCRP D-12 Final Report 48 The data recorder is the blue instrument at the bottom of the photograph. The instrument in the middle of the photo is the accelerometer signal conditioner. Read the entire page →
From page 52... ... TCRP D-12 Final Report 49 Figure 16: Typical Residential Measurement Setup Figure 17: Typical Exterior Measurement Setup Read the entire page →
From page 53... ... TCRP D-12 Final Report 50 Figure 18: Typical Grid Measurement Setup Figure 19: Typical Reference Measurement Setup Read the entire page →
From page 54... ... TCRP D-12 Final Report 51 5.3.3 Field Log Sheets and Field Crew Field log sheets were prepared for each type of measurement; reference, residence interior, residence exterior and grid point. Samples of the log sheets may be found in Appendix C Read the entire page →
From page 55... ... TCRP D-12 Final Report 52 trains had clearly different vibration characteristics. Trains were not separated into groups because 1) Read the entire page →
From page 56... ... TCRP D-12 Final Report 53 Figure 21: Example of DirectionDependent Vibration Spectra This is an example where vibration from inbound and outbound trains had consistently different characteristics. Trains on the closer track exhibited higher levels between 80 Hz and 100 Hz. Read the entire page →
From page 57... ... TCRP D-12 Final Report 54 In addition, the duration of each event was calculated and stored. (The duration was defined as the time between the 3 dB down points that were used for calculating Leq.) Read the entire page →
From page 58... ... TCRP D-12 Final Report 55 Table 14: Summary of Site-Level Measurement Metrics Measure Number of Related Measures Description Passby Duration 1 Based on 3 dB down points from 1 second Lmax. Leq, Velocity and Sound 20* Read the entire page →
From page 59... ... TCRP D-12 Final Report 56 eliminated from the analysis. Note that trains that caused unusually high vibration and/or noise levels were retained in the analysis because these trains were part of the residents' vibration exposure. Read the entire page →
From page 60... ... TCRP D-12 Final Report 57 Dallas, brownstones in New York and Boston, and two story duplexes with full basements in Toronto and Boston. The middle two graphs in Figure 22 show the relationships between indoor sound and outdoor vibration, and indoor sound and indoor vibration, respectively (all with no weighting applied) Read the entire page →
From page 61... ... TCRP D-12 Final Report 58 Table 15: Overall Vibration and Noise Levels Measured at Residences Transit System Survey Label Dist. from Track CL (m) Read the entire page →
From page 62... ... TCRP D-12 Final Report 59 Figure 22: Relationships between Indoor and Outdoor Measurements Read the entire page →
From page 63... ... TCRP D-12 Final Report 60 5.5.2 Relationships between Metrics As discussed earlier, a number of different measures have been used or considered for characterizing human response to ground-borne vibration and noise generated by rail transit operations. A goal of this study was to investigate which measures were best correlated with human response to the vibration/noise. Read the entire page →
From page 64... ... TCRP D-12 Final Report 61 Figure 23: Relationship between Site Average Outdoor Lmax and Leq Lmax is the maximum passby level using a 1 second RMS average. Leq is average level over the 3 dB down points. Read the entire page →
From page 65... ... TCRP D-12 Final Report 62 Figure 24: Relationship between Un-weighted and Weighted Velocity Levels Both graphs compare weighted vibration velocity to the un-weighted velocity. The left plot uses ANSI weighting, which rolls off at frequencies lower than 8 Hz. Read the entire page →
From page 66... ... TCRP D-12 Final Report 63 Figure 26: Relationship between A-weighted and Un-weighted Velocity Level Measures of Exposure: A potential shortcoming associated with most current ground-borne vibration standards is they are based on the absolute train vibration level, and have little ability to account for the number of events per day, or the duration of a typical event. It seems reasonable that longer trains would be more annoying than shorter trains, and that annoyance would increase with the frequency of service in general, and nighttime service in particular. Read the entire page →
From page 67... ... TCRP D-12 Final Report 64 The exposure metrics most familiar to the acoustics community are based on the equivalent sound level (Leq) over a period of time, most commonly 24 hours or one hour. Read the entire page →
From page 68... ... TCRP D-12 Final Report 65 Figure 27: Comparison of RMQ and RMS Exposure Comparison of site average SEL calculated using RMS and RMQ averaging for all exterior measurement positions. SEL is the total energy of the event normalized to 1 second. Read the entire page →
From page 69... ... TCRP D-12 Final Report 66 the measurement sites could be an indication that it is a characteristic of the Toronto situation (track, tunnel, rolling stock, soil conditions) Read the entire page →
From page 70... ... TCRP D-12 Final Report 67 clear that Toronto is the only system where the maximum level occurs at a distinct peak in the vibration spectrum. As discussed above, the 50 Hz peak in the Toronto vibration spectrum occurred at most of the measurement locations. Read the entire page →
From page 71... ... TCRP D-12 Final Report 68 Figure 28: Average Vibration Velocity Spectra, Toronto Outdoor Measurement Sites Read the entire page →
From page 72... ... TCRP D-12 Final Report 69 Figure 29: Average Vibration Velocity Spectra, New York Outdoor Measurement Sites Read the entire page →
From page 73... ... TCRP D-12 Final Report 70 Figure 30: Average Vibration Velocity Spectra, Boston Blue Line Outdoor Sites Read the entire page →
From page 74... ... TCRP D-12 Final Report 71 Figure 31: Average Vibration Velocity Spectra, Boston Back Bay Outdoor Sites Read the entire page →
From page 75... ... TCRP D-12 Final Report 72 Figure 32: Average Vibration Velocity Spectra, Dallas Outdoor Measurement Sites Read the entire page →
From page 76... ... TCRP D-12 Final Report 73 Figure 33: Average Vibration Velocity Spectra, Sacramento Outdoor Measurement Sites Read the entire page →
From page 77... ... TCRP D-12 Final Report 74 Figure 34: Average Vibration Velocity Spectra, Outdoor Measurement Sites Read the entire page →
From page 78... ... TCRP D-12 Final Report 75 5.5.3.2 Outdoor to Indoor Adjustments At each of the residential test locations, the vibrations were measured simultaneously inside and outside of the residence. Noise was also measured inside the residence. Read the entire page →
From page 79... ... TCRP D-12 Final Report 76 Figure 42 shows the combined average curves obtained using different acceptance criteria in terms of the amount that a data point must exceed the background to be included in the average. The acceptance criteria range from no data points being excluded, to excluding all data points that do not exceed the average background level by at least three standard deviations. Read the entire page →
From page 80... ... TCRP D-12 Final Report 77 Figure 35: Average Outdoor-to-Indoor Differences, Toronto Solid blue line is average of all sites, dashed blue lines are ± 1 standard deviation. Only levels that were more than 2 standard deviations greater than background levels were included in the calculation of average differences. Read the entire page →
From page 81... ... TCRP D-12 Final Report 78 Figure 36: Average Outdoor-to-Indoor Differences, New York Solid blue line is average of all sites, dashed blue lines are ± 1 standard deviation. Only levels that were more than 2 standard deviations greater than background levels were included in the calculation of average differences. Read the entire page →
From page 82... ... TCRP D-12 Final Report 79 Figure 37: Average Outdoor-to-Indoor Differences, Boston Solid blue line is average of all sites, dashed blue lines are ± 1 standard deviation. Only levels that were more than 2 standard deviations greater than background levels were included in the calculation of average differences. Read the entire page →
From page 83... ... TCRP D-12 Final Report 80 Figure 38: Average Outdoor-to-Indoor Differences, Dallas Solid blue line is average of all sites, dashed blue lines are ± 1 standard deviation. Only levels that were more than 2 standard deviations greater than background levels were included in the calculation of average differences. Read the entire page →
From page 84... ... TCRP D-12 Final Report 81 Figure 39: Average Outdoor-to-Indoor Differences, Sacramento Solid blue line is average of all sites, dashed blue lines are ± 1 standard deviation. Only levels that were more than 2 standard deviations greater than background levels were included in the calculation of average differences. Read the entire page →
From page 85... ... TCRP D-12 Final Report 82 Figure 40: Average Outdoor-to-Indoor Differences, All Sites Solid blue line is average of all sites, dashed blue lines are ± 1 standard deviation. Only levels that were more than 2 standard deviations greater than background levels are included in the calculation of average differences. Read the entire page →
From page 86... ... TCRP D-12 Final Report 83 Figure 41: Average Outdoor-to-Indoor Differences for Each Transit System Read the entire page →
From page 87... ... TCRP D-12 Final Report 84 Figure 42: Comparison of Average Outdoor-to-Indoor Differences, using Different Data Thresholds "N x Stdev" indicates that only levels that exceeded the background level by at least N times the standard deviation were included in the average. Read the entire page →
From page 88... ... TCRP D-12 Final Report 85 Figure 43: Comparison of Indoor Vibration and Sound in Three New York Residences The three brownstone residences were adjacent to each other and appeared to be of similar construction and vintage. All three measurements were made in the living room on the first floor. Read the entire page →
From page 89... ... TCRP D-12 Final Report 86 4. The vibration levels at the two neighboring grid points were then adjusted to the same setback distance of the residence using a linear interpolation between the perpendicular grid points. Read the entire page →
From page 90... ... TCRP D-12 Final Report 87 5.7 Summary of Measurement Observations The following points summarize the key observations regarding the D-12 field measurement data. • The 1/3 octave band vibration spectra at most sites were greatest between 20 Hz and 80 Hz. Read the entire page →
From page 91... ... TCRP D-12 Final Report 88 Figure 45: Calculated Vibration Exposure at D-12 Residences based on Vibration Level Train Leq is the RMS average vibration over the 3 decibel down points. "Exposure" is the equivalent vibration level from train traffic distributed over 24-hours (analogous to Leq(24) Read the entire page →

From page 47...

... TCRP D-12 Final Report 44 5. FIELD MEASUREMENTS 5.1 Measurement Overview The overall goal of the field measurements was to estimate the exposure of each survey respondent to ground-borne vibration and noise using a wide variety of exposure metrics.