treasure valley road dust study: final report - ResearchGate

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250 200 PM2.5 signal (mg/m 3 ) 150 100 y = 0.3913x R 2 = 0.8852 50 0 0 50 100 150 200 250 PM10 signal (mg/m 3 ) Figure 3-8. PM 10 and PM 2.5 DustTrak signals when they are collocated in the same sampling plenum within the TRAKER. An R 2 of 0.89 shows that the two measures are strongly correlated and that on average, the PM 2.5 value is 39% of the PM 10 value. Table 3-1 Validity criteria applied to each 1-second TRAKER data point. Parameter Criterion Threshold Description Speed > Acceleration < Deceleration < Wheel Angle < 5 m/s – paved roads (~11 miles/hr) 1.5 m/s – unpaved Roads (~3.5 miles/hr) 0.5 m/s 2 (~1.1 miles/hr/s) 0.5 m/s 2 (~1.1 miles/hr/s) 3 degrees with respect to the vehicle body Minimize disturbances due to ambient winds. Criterion is relaxed for unpaved roads because it is necessary to travel at lower speeds due to high dust emissions that overwhelm the instruments on board the TRAKER. Lateral shear during acceleration and transient airflow around the TRAKER inlets render TRAKER measurements during times of high acceleration unreliable. Applying the brakes releases dust particles and may result in false high road dust readings. Turns cause the front wheels to form an angle with the vehicle body. This in turn changes the orientation of the TRAKER inlets with respect to the front tires. Data associated with sharp turns are not valid. The vehicle speed can become important under conditions of moderate to high winds. If the TRAKER is not moving fast enough, crosswinds and fluctuations in the ambient winds can 3-10
lead to unsteady flow conditions between the front tire and the inlet. To avoid this possibility, a minimum speed of 5 m/s is required to consider a data point valid. This criterion is relaxed for unpaved roads (1.5 m/s) where traveling at high speeds can causethe DustTraks and PSAs on board the TRAKER to be overwhelmed with high dust concentrations. Acceleration/deceleration criteria (< 0.5 m/s 2 ) are also applied to the TRAKER measurement. During periods of high acceleration, the flow regime around the inlets may be transient; during periods of deceleration, dust from the brakes may influence the particle concentrations behind the front tire. In addition, the wheel angle must be less than 3 degrees with respect to the vehicle body. This is to ensure that the orientation of the inlets with respect to the front tires is not changing over the course of the measurements. The criteria shown in Table 3-1 are based on empirical observations and statistical analyses of the TRAKER measurement under a variety of driving regimes. They are conservative and intended to ensure that the measurements used in this study are valid. 3.3.2 Inlet Loss To assess the magnitudes of particle losses in the sample inlet lines, particle concentrations at the inlet were compared to concentrations measured by the instruments attached to the plena. The TRAKER was parked perpendicular to and 15 meters downwind of an unpaved road. Two PSAs were placed within 5 cm of the inlet opening (Figure 3-9). Inside the TRAKER, the manifold was outfitted with the usual suite of instruments, one PSA, one DustTrak with a PM 10 inlet, and one DustTrak with a PM 2.5 inlet. Because they have directionsensitive inlets, and due to their physical configuration, t iwas not possible to place a DustTrak close enough to the inlet opening for comparison with the measurement inside the TRAKER. Instead, test results for the DustTrak were inferred from the results for the PSA. A second vehicle was driven back and forth on the unpaved road to simulate the particle concentration range that would occur at the inlet during routine operation (Figure 3-10). This test was performed for a minimum of 30 minutes for each of the three inlets. For the inl ets behind the left and right front tires, the test was conducted for the normal configuration, as well as for the case where the dilution system was in use. The concentrations measured by each instrument were averaged over the period of the test for inter-comparison purposes. Figure 3-11 shows the fractional line losses associated with each particle size measured by the PSA for the three inlets. The figure also shows the collocated precision for the PSA. The aerodynamic particle size shown on the x-axis is calculated by assuming that the optical particle diameter is equivalent to the Stokes diameter and that the particles are spherical with a density of 2.6. Based on these assumptions, the aerodynamic diameter is equal to the optical diameter times the square root of the particle density (Seinfeld and Pandis, 1998). Line losses in the smallest size bin are not consistent with physical expectation and are probably marred by artifacts introduced by instrument error. However, we note that the mass associated with this bin represents less than 0.1% of the mass of PM 10 and that this error is negligible in the context of the present work. Except for the smallest size bin, there are no significant differences in line losses between the left, right, and background inlets, i.e. differences in line losses between inlets are not greater than twice the precision which is the criterion for deciding whether or not two measurements are significantly different. Thus, the left, background, and right line losses are adequately represented by Figure 3-12 which shows the average line losses for all three inlets. Note that though negative line losses do not have a physical meaning, they are retained in order to correct for inter-instrument biases. 3-11
Page 1: TREASURE VALLEY ROAD DUST STUDY: FI
Page 5 and 6: EXECUTIVE SUMMARY The Idaho Departm
Page 7 and 8: TABLE OF CONTENTS 1. INTRODUCTION..
Page 9: 6.3 DISCUSSION ....................
Page 12 and 13: are strongly correlated and that on
Page 14 and 15: Figure 4-17. Map of street sweeper
Page 16 and 17: xvi
Page 18 and 19: Table 5-3. Speeds and VKT by county
Page 20 and 21: Table A-28. Laboratory Silt Analysi
Page 22 and 23: ?? To assess the impact of winterti
Page 25 and 26: 2. SILT MEASUREMENTS For this study
Page 27 and 28: vehicle tires. The lengths of the s
Page 29 and 30: Figure 2-1. Map of Sample Collectio
Page 31 and 32: Table 2-5 Silt Content and Silt Loa
Page 33: collectors. In contrast, summer sil
Page 36 and 37: 3.2 TRAKER Measurements For the TVR
Page 38 and 39: introduced by the carbon vanes insi
Page 40 and 41: 3.2.4.1 Data Acquisition The TRAKER
Page 42 and 43: Figure 3-6 shows the TRAKER coeffic
Page 46 and 47: Line losses associated with the Dus
Page 48 and 49: 1.2 1 Left Diluted Right Diluted Pr
Page 50 and 51: Table 3-2. Regression exponents for
Page 52 and 53: 3.4.2 Flux Calculation from Meteoro
Page 54 and 55: 12.2 m 0.16 9.0 m 0.05 5.7 m 0.22 4
Page 56 and 57: 400 Ford Ranger on NS Road by DW1 4
Page 58 and 59: ceiling can be further stretched to
Page 60 and 61: 100 sL = 2.5717(T*) 0.4741 R 2 = 0.
Page 62 and 63: 4.1.1 Converting TRAKER Data Into E
Page 64 and 65: Table 4-1. (cont) GIS coverages use
Page 66 and 67: Table 4-1. (cont) GIS coverages use
Page 68 and 69: a. b. Figure 4-1. Map of TRAKER Str
Page 70 and 71: egressions, R 2 and P-values are al
Page 72 and 73: Summer - Ada - Rural Summer - Ada -
Page 74 and 75: The average emissions factor is 6.7
Page 76 and 77: Figure 4-5. TRAKER Loop 4.3.1 Tempo
Page 78 and 79: weeks prior to being swept. While t
Page 80 and 81: 4.3.2 Meteorological Effects on Unp
Page 82 and 83: Section 1 Section 2 Section 3 Figur
Page 84 and 85: Figure 4-13. Johnston HSD mechanica
Page 86 and 87: Approximately 8 hours after the ini
Page 88 and 89: One-second emissions potentials (i.
Page 91 and 92: 5. EMISSIONS INVENTORIES FOR THE TR
Page 93 and 94: where E i.10 is the emissions in gr
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County Setting Road Class Speed (m/
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January, February, and March were u
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5.1.3.2a January 1 - 9, 2000, 2010,
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Table 5-9 Precipitation and snow co
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complete link-level emissions inven
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Table 5-14. Distributions of averag
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Taken on an average annual basis, T
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Z n , K zn , ? c/ ? z n Z 3 , K z3
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Table 6-1. Aerodynamic particle siz
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14 m 0 s 15 s 30 s 60 s 120 s 240 s
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Furthermore, the vertical profile o
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?? Sieving each sample to obtain a
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7-4 Table 7-1. Source Profile Key M
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Table 6-1 (continued). Table of geo
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Treasure Valley Road Dust Winter Pa
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7.3 Source Profile Summary This a p
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Table 7-4. Source profiles of Summe
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Table 7-6. Source profiles of Winte
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Bliss experiments were significant
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section was swept with a vacuum swe
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8.3 Differences Between Emissions M
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determine at this time what fractio
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sweepers to reduce PM 10 emissions
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McMahon T.A., and P.J. Denison (197
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Figure A-1. Map of Sample Collectio
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Table A-2. Summer 2001 Silt Samplin
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Table A-3. Laboratory Silt Analysis
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Figure A-3. Map of Silt Loading Loc
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Table A-10. Laboratory Silt Analysi
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Figure A-11. Sampling locations of
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APPENDIX B. BOISE PRECIPITATION AND
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Pecentile among days with precipita
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A.1 Wind speed The cumulative frequ
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APPENDIX C : EMISSIONS INVENTORIES:
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C.1.1.2a Field List for worksheets
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values specified by AP-42 and do no
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