treasure valley road dust study: final report - ResearchGate

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the emissions calculation is that the vehicle kilometers traveled on residential roads within the rectangle ABCD are equal to the vehicle kilometers traveled on the TDM links 1,2,3, and 4. 5.1.1.2a PM 10 and PM 2.5 Correlation Emissions factors for PM 2.5 were assumed to be a constant proportion of the PM 10 emissions factors (See section 4.1.3 for details). For paved roads, PM 10 emissions factors were multiplied by 0.057 to obtain PM 2.5 emissions factors. 5.1.1.3 Accounting for precipitation AP-42 (USEPA, 1999) does not prescribe a strategy for accounting for the reduction of road dust emissions due to rain. However, it is clear, both by casual observation and by analogy to unpaved roads, that emissions of paved road dust must be discounted to account for precipitation. Because TRAKER instruments are sensitive to moisture, it was not possible to directly measure road dust emissions during, or even shortly after a rain event. In the absence of a known precedence, a conservative engineering guess was applied. The engineering approach was based on the observation that after even a brief rain shower (corresponding to between 0..25 mm to 0.50 mm of rain), roads remain visibly wet for approximately one hour. Moisture in the asphalt matrix may retard emissions even afterthe road “looks” dry. As a conservative approach, paved road dust emissions were assumed to be 0 for 30 minutes for each 0.25 mm of precipitation. No attempt was made to differentiate between the effects of snowfall and rainfall for paved roads since no supporting data are available. Table 5-4 shows the distribution of precipitation by month for the Treasure Valley area. To obtain the fraction of time paved road emissions are zero, for each month, the average daily precipitation is multiplied by 0.5 hours and divided by 24 hours. To obtain actual monthly emissions, the dry paved road emission rate is multiplied by 1-(fraction of time paved road emissions are zero). For example, for January, paved road emissions would be calculated by multiplying the dry emission rate by 1-0.10 = 0.90. Table 5-4. Summary of precipitation statistics by month, Boise airport January 1940-October 2001. Month Fraction of days with 0.25 mm or more precipitation Average daily precipitation (mm) Average daily precipitation when >0 Fraction of time Paved Road emissions are zero Jan 0.38 1.17 0.12 0.10 Feb 0.36 1.04 0.11 0.09 Mar 0.31 1.02 0.13 0.08 Apr 0.28 1.02 0.15 0.08 May 0.25 1.04 0.16 0.09 Jun 0.20 0.74 0.15 0.06 Jul 0.08 0.23 0.11 0.02 Aug 0.08 0.23 0.12 0.02 Sep 0.12 0.51 0.16 0.04 Oct 0.19 0.66 0.14 0.05 Nov 0.34 1.14 0.13 0.09 Dec 0.37 1.12 0.12 0.09 Annual 0.25 0.81 0.13 0.07 5.1.1.4 Winter average and annual average emissions Winter emissions for the year 2000 inventory were calculated based on the winter emissions potentials shown in Table 5-1 and Table 5-2. Precipitation data for the months of 5-6
January, February, and March were used to account for the effects of precipitation on road dust emissions. Yearly average emissions were calculated by applying the summer emissions potentials in Table 5-1 and Table 5-2 to all non-Winter (i.e. not January, February, or March) months. The effect of precipitation for each non-winter month was weighted by the number of days in that month. The average emissions per day for winter were multipliedby the number of days (90) and added to the average emissions per non-winter day multiplied by the number of days (275). The total was divided by 365 to arrive at an annual-average emissions inventory. 5.1.2 Future year paved road emissions Emissions inventories for future years were calculated similarly to the year 2000. Traffic Demand Model results for the years 2010, 2015, and 2020 were combined with emissions potentials to obtain emissions factors on a link-by-link basis. Since no actual TRAKER data are available for future years, the emissions potentials for future year inventories were exclusively calculated by equation (5-2) and Table 5-1 and Table 5-2. Note that the road setting (urban/rural) was re-evaluated for each link in the TDM for each year. The future year populations for individual census tracts were calculated by summing the number of houses in each Traffic Analysis Zone that is contained within the tract and scaling with year 2000 populations. This approach assumes that the number of people per household remains constant between the year 2000 and all future years. A map delineating the urban/rural zones for each of the TDM years modeled is shown in Figure 5-2. For precipitation corrections, the historical average correction factors shown in Table 5-4 were used. 5.1.3 Episodic paved road emissions In addition to the years, 2000, 2010, 2015, and 2020, daily emissions inventories were also assembled for January 1-9, 1991 and December 20-26, 1999. For days without precipitation, winter dry paved roads emissions were used. For days with precipitation, for each 0.25mm 30 minutes of zero emissions were assumed. The total number of hours of zero emissions for a given day was calculated, subtracted from 24, and then divided by 24 to give a precipitation modifier ratio. This ratio was then multiplied by the dry paved road emissions rate to give the paved road emissions for that day. 5.1.3.1 December 20 –26, 1999 Because of the episode’s proximity to the beginning of the year 2000, year 2000 TDM results were used to calculate daily dry paved road emissions rates. 5.1.3.2 January 1 – 9, 1991 For the January 1-9, 1991 episode, the dry paved emissions were estimated from the year 2000 Traffic Demand Model network. The total vehicle miles traveled (VMT) in 1991 were estimated by regressing the year 2000, 2010, 2015, and 2020 Total VMTs (see Figure 5-3). The VMT for 1991 (6.77 million miles) was then divided by the VMT for 2000 (8.79 million miles) to arrive at a correction factor for 1991 dry paved emissions. Based on this analysis, 1991 dry paved emissions were 77.1% of 2000 dry paved emissions. 5-7
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TREASURE VALLEY ROAD DUST STUDY: FI
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EXECUTIVE SUMMARY The Idaho Departm
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TABLE OF CONTENTS 1. INTRODUCTION..
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6.3 DISCUSSION ....................
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are strongly correlated and that on
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Figure 4-17. Map of street sweeper
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xvi
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Table 5-3. Speeds and VKT by county
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Table A-28. Laboratory Silt Analysi
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?? To assess the impact of winterti
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2. SILT MEASUREMENTS For this study
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vehicle tires. The lengths of the s
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Figure 2-1. Map of Sample Collectio
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Table 2-5 Silt Content and Silt Loa
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collectors. In contrast, summer sil
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3.2 TRAKER Measurements For the TVR
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introduced by the carbon vanes insi
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3.2.4.1 Data Acquisition The TRAKER
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Figure 3-6 shows the TRAKER coeffic
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250 200 PM2.5 signal (mg/m 3 ) 150
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Page 48 and 49: 1.2 1 Left Diluted Right Diluted Pr
Page 50 and 51: Table 3-2. Regression exponents for
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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
Page 95: County Setting Road Class Speed (m/
Page 99 and 100: 5.1.3.2a January 1 - 9, 2000, 2010,
Page 101 and 102: Table 5-9 Precipitation and snow co
Page 103 and 104: complete link-level emissions inven
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Page 107: Taken on an average annual basis, T
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Page 112 and 113: Table 6-1. Aerodynamic particle siz
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Page 116 and 117: Furthermore, the vertical profile o
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Page 120 and 121: 7-4 Table 7-1. Source Profile Key M
Page 122 and 123: Table 6-1 (continued). Table of geo
Page 124 and 125: Treasure Valley Road Dust Winter Pa
Page 127 and 128: 7.3 Source Profile Summary This a p
Page 129 and 130: Table 7-4. Source profiles of Summe
Page 131: Table 7-6. Source profiles of Winte
Page 134 and 135: Bliss experiments were significant
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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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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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