treasure valley road dust study: final report - ResearchGate

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The average emissions factor is 6.7 [g/vkt] for all winter roads and 5.0 [g/vkt] for all summer roads. Differences between summer and winter are discussed at greater length in section 4.3.1. Overall, Ada County emissions factors (6.1 [g/vkt]) were higher than those for Canyon County (5.3 [g/vkt]). However, when segregated by season, Ada emissions factors are lower than Canyon in the summer (Ada-4.8 [g/vkt] vs. Canyon-5.3 [g/vkt]), with the converse being true in winter (Ada-7.4 [g/vkt] vs. Canyon-5.3 [g/vkt]). Perhaps Ada County emissions are elevated in the winter because Ada County performs road sanding during snow events either more frequently or to a greater extent than Canyon County. Rural roads exhibited lower emissions factors than urban roads (4.9 [g/vkt] vs. 6.9 [g/vkt]). Part of the discrepancy is due to rural roads having slightly higher speeds than their urban counterparts. In addition, rural roads are probably not as likely to receive as much sand prior to and during snow events. In comparing the emissions potentials among the different road classes, it is quite clear that in general, higher speed roads are cleaner than lower speed roads. For interstates, arterials, and collectors, the emissions factors also follow the same trend. However, local/residential road emissions factors are lower than would be expected based on the average speeds of those roads. It is important to note that this may be in part due to the fact that residential roads are not represented as physical entities in the Traffic Demand Model. Therefore, speeds that are associated with residential roads and are used to calculate emissions factors may be inaccurate. 4.2.2 Unpaved Roads Figure 4-4 shows the unpaved roads that were surveyed with TRAKER. Since accurate traffic volume and speed information were not available, all unpaved roads were averaged together to obtain one emissions factor for dry conditions. The effect of precipitation on unpaved emissions is discussed in section 4.3.2. Table 4-7 shows the emissions potentials calculated for unpaved roads measured with TRAKER. The procedure for measurement and calculation is the same as for paved roads except that summer unpaved roads were surveyed using the TRAKER dilution system described in Section 3. There are some minor differences between summer and winter measurements on the same stretch of road. For example, the emissions potential for Pierce Park Dr. was 18.4 [g/vkt/mps] in the winter, and 6.3 [g/vkt/mps] in the summer. On the other hand, both the Cloverdale Farm loop and Dry Creek Road 2 exhibit similar emissions potentials in both seasons. Overall, within the uncertainties of the measurements, the average emissions potentials for dry unpaved roads do not differ between winter and summer. 4.3 TRAKER Loop A set of roads that comprise a closed “loop” was traversed with the TRAKER repeatedly during the summer and winter field campaigns. The loop is shown schematica lly in Figure 4-5 and turn-by-turn directions are listed in Table 4-8. For paved roads, the TRAKER loop data allow for consideration of temporal trends in road dust emissions potentials. The TRAKER could not be used when roads were still wet after a rain event because excessive water in the inlets could compromise the accuracy of the measurement and ruin the onboard instruments. Therefore, it was not possible to examine the change in road dust emissions potential during and/or immediately after a rainstorm. However, for unpaved roads, the effect of precipitation on emissions potentials can be seen for up to two days after a rain event without causing damage to the TRAKER instruments. The effect of precipitation on unpaved road 4-14
emissions potentials was examined by comparing meteorological parameters to TRAKER measurements. Figure 4-4. Unpaved roads surveyed during the Treasure Valley Road Dust Study. The gray lines correspond to Ada County roads and the black regions correspond to unpaved roads surveyed with TRAKER. Table 4-7. Unpaved Roads and Corresponding Emissions Potentials Road Surveyed Winter Emissions Potential (g/vkt/mps) Summer Emissions Potential (g/vkt/mps) Cartwright 13.6 Cloverdale Farm Loop 5.8 3.5 Dry Creek 1 3.1 Dry Creek 2 6.2 6.6 Howry 6.0 MacFarlane Creek 14.2 Pierce Park 18.4 6.3 Peak Dam Access Road 10.8 Average 9.1 8.3 Standard Error 2.8 1.8 Overall Average 8.6 Stanadard Error 1.5 4-15
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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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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
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Page 40 and 41: 3.2.4.1 Data Acquisition The TRAKER
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Page 44 and 45: 250 200 PM2.5 signal (mg/m 3 ) 150
Page 46 and 47: Line losses associated with the Dus
Page 48 and 49: 1.2 1 Left Diluted Right Diluted Pr
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Page 52 and 53: 3.4.2 Flux Calculation from Meteoro
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Page 62 and 63: 4.1.1 Converting TRAKER Data Into E
Page 64 and 65: Table 4-1. (cont) GIS coverages use
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Page 68 and 69: a. b. Figure 4-1. Map of TRAKER Str
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Page 82 and 83: Section 1 Section 2 Section 3 Figur
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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 and 96: County Setting Road Class Speed (m/
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Page 99 and 100: 5.1.3.2a January 1 - 9, 2000, 2010,
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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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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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