#• \ ®! % ^ *1 PRO*^ 2020 National Emissions Inventory Technical Support Document: Dust - Paved Roads ------- ------- EPA-454/R-23-001w March 2023 2020 National Emissions Inventory Technical Support Document: Dust - Paved Roads U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Air Quality Assessment Division Research Triangle Park, NC ------- Contents List of Tables i 23 Dust - Paved Roads 23-1 23.1 Sector Descriptions and Overview 23-1 23.2 EPA-developed estimates 23-1 23.2.1 Emission factors 23-1 23.2.2 Activity data 23-3 23.2.3 Allocation 23-4 23.2.4 Controls 23-4 23.2.5 Meteorological adjustment 23-5 23.2.6 Improvements/Changes in the 2020 NEI 23-5 23.2.7 Puerto Rico and Virgin Islands 23-5 23.3 References 23-5 List of Tables Table 23-1: SCCs in the paved road dust sector 23-1 Table 23-2: Assumed paved roads silt loading by road type (gm2) based on ADTV range 23-2 Table 23-3: Average vehicle weights by FWHA vehicle class 23-2 Table 23-4: MOVES and FWHA vehicle type crosswalk 23-3 Table 23-5: FHWA road types 23-3 Table 23-6: Penetration rate of Paved Road vacuum sweeping 23-4 l ------- 23 Dust - Paved Roads 23.1 Sector Descriptions and Overview The paved road dust sector reflects emissions of particulate matter from vehicles driving over paved roads. The SCCs that belong in this sector are provided in Table 23-1. EPA estimates emissions for total fugitives only. Fugitive dust emissions from paved road traffic were estimated for PM10-PRI, PM10-FIL, PM25-PRI, and PM25-FIL. Since there are no PM-CON emissions for this category, PM10-PRI emissions are equal to PM10-FIL emissions and PM25-PRI emissions are equal to PM25-FIL emissions. Ta lie 23-1: SCCs in the paved road dust sector see see Level 1 SCC Level 2 SCC Level 3 SCC Level 4 2294000000 Mobile Sources Paved Roads All Paved Roads Total: Fugitives 2294000002 Mobile Sources Paved Roads All Paved Roads Total: Sanding/Salting - Fugitives 23.2 EPA-developed estimates Uncontrolled paved road emissions were calculated at the county level by roadway type for the year 2020. This was done by multiplying the county/roadway class paved road vehicle miles traveled (VMT) by the appropriate paved road emission factor. Next, control factors were applied to the paved road emissions in PMio nonattainment and maintenance status counties. Emissions by roadway class were then totaled to the county level for reporting in the NEI. The following provides further details on the emission factor equation, determination of paved road VMT, and controls. 23.2.1 Emission factors Re-entrained road dust emissions for paved roads were estimated using paved road VMT and the emission factor equation from AP-42 [ref 1]: E = [kx(sL)a91x(W)102] Where: E = paved road dust emission factor (g/VMT) k = particle size multiplier (g/VMT) sL = road surface silt loading (g/ m2) (dimensionless in eq.) W = average weight (tons) of all vehicles traveling the road (dimensionless in eq.) The particle size multipliers for both PM10-PRI/-FIL and PM25-PRI/-FIL for paved roads came from AP- 42. Paved road silt loadings were assigned to each of the fourteen functional roadway classes (seven urban and seven rural) based on the average annual daily traffic volume (ADTV) of each functional system by county [ref 2], The silt loading values per average daily traffic volume come from the ubiquitous baseline values from Section 13.2.1 of AP-42 and are provided in Table 23-2. 23-1 ------- Table 23-2: Assumed paved roads silt loading by roac type (gm2) Dased on ADTV range FHWA road type 0-499 500-4,999 5,000-9,999 10,000+ Rural Interstate 0.015 0.015 0.015 0.015 Rural Other Freeways and Expressways 0.015 0.015 0.015 0.015 Rural Other Principal Arterial 0.6 0.2 0.06 0.03 Rural Minor Arterial 0.6 0.2 0.06 0.03 Rural Major Collector 0.6 0.2 0.06 0.03 Rural Minor Collector 0.6 0.2 0.06 0.03 Rural Local 0.6 0.2 0.06 0.03 Urban Interstate 0.015 0.015 0.015 0.015 Urban Other Freeways and Expressways 0.015 0.015 0.015 0.015 Urban Other Principal Arterial 0.6 0.2 0.06 0.03 Urban Minor Arterial 0.6 0.2 0.06 0.03 Urban Major Collector 0.6 0.2 0.06 0.03 Urban Minor Collector 0.6 0.2 0.06 0.03 Urban Local 0.6 0.2 0.06 0.03 Average daily traffic volume (ADTV) was calculated by dividing an estimate of VMT by functional road length and then by 365. State FHWA road length by functional road type data was broken down to the county level by multiplying by the ratio of county VMT to state VMT for each FHWA road type. To better estimate paved road fugitive dust emissions, the average vehicle weight was estimated by road type for each county in the U.S. based on the VMT by vehicle type. The VMT for each vehicle type (per MOVES road type and county) was divided by the sum of the VMT of all vehicle types for the given road type in each county. This ratio was multiplied by the vehicle type mass (see Table 23-3) and summed to road type for each county to calculate a VMT-weighted average vehicle weight for each county/road type combination in the database. The VMT-weighted average vehicle weight by MOVES vehicle type was converted to FWHA vehicle type using the crosswalk in Table 23-4 to be used in the emission factor equation above. Ta lie 23-3: Average vehicle weights by FWHA vehicle class Source Mass MOVES Vehicle Type (tons) Motorcycle 0.285 Passenger Car 1.479 Passenger Truck 1.867 Light Commercial Truck 2.0598 Intercity Bus 19.594 Transit Bus 16.556 School Bus 9.070 Refuse Truck 23.114 Single Unit Short-haul Truck 8.539 Single Unit Long-haul Truck 6.984 Motor Home 7.526 Combination Short-haul Truck 22.975 23-2 ------- MOVES Vehicle Type Source Mass (tons) Combination Long-haul Truck 24.601 Table 23-4: MOVES and FWHA vehicle type crosswalk MOVES Road Type Description FWHA Road Type Rural Restricted Access Rural Interstate Rural Unrestricted Access Rural Principal Arterial Rural Unrestricted Access Rural Minor Arterial Rural Unrestricted Access Rural Collector Rural Unrestricted Access Rural Local Urban Restricted Access Urban Interstate Urban Unrestricted Access Urban Principal Arterial Urban Unrestricted Access Urban Minor Arterial Urban Unrestricted Access Urban Collector Urban Unrestricted Access Urban Local *Note: Other Freeways and Expressways were not included in the crosswalk, and so were assumed to be restricted access like Interstates. 23.2.2 Activity data Generally, VMT on US roads can be obtained from the Federal Highway Administration (FHWA). Total VMT in each county is provided by FHWA to EPA for use in EPA's MOtor Vehicle Emission Simulator (MOVES) model to calculate emissions for the mobile sector. The road dust methodology uses these same county-level VMT data from FHWA. FHWA categorizes roads into 14 different types based on road function and access; these road types can be found in Table 23-5. Table 23-5: FHWA road types FHWA Road Type Rural Interstate Rural Other Freeways and Expressways Rural Other Principal Arterial Rural Minor Arterial Rural Major Collector Rural Minor Collector Rural Local Urban Interstate Urban Other Freeways and Expressways Urban Other Principal Arterial Urban Major Collector Urban Minor Collector Urban Local Urban Minor Arterial 23-3 ------- To estimate the portion of the total VMT occurring on paved roads, first the VMT on unpaved roads were estimated using a procedure to estimate the proportion of unpaved vs. paved VMT (see the full description for VMT development in the "Activity Data" subsection under the Unpaved Road Dust section below). The estimated VMT on unpaved roads was then subtracted from the total VMT from MOVES to estimate the VMT on paved roads for each road type category where applicable. 23.2.3 Allocation County level emissions were calculated by multiplying the county unpaved VMT (by road type) by the emission factors calculated according to Section 23.2.1 above and aggregating based on county and urban/rural classification. 23.2.4 Controls Paved road dust controls were applied by county to urban and rural roads in serious PMio nonattainment areas and to urban roads in moderate PMio nonattainment areas. The assumed control measure is vacuum sweeping of paved roads twice per month. A control efficiency of 79% was assumed for this control measure [ref 3], The assumed rule penetration varies by roadway class and PMio nonattainment area classification (serious or moderate). The rule penetration rates are shown in Table 23-6. Rule effectiveness was assumed to be 100% for all counties where this control was applied. Table 23-6: Penetration rate of Paved Roac vacuum sweeping PMio Nonattainment Status Roadway Class Vacuum Sweeping Penetration Rate Moderate Urban Freeway & Expressway 0.67 Moderate Urban Minor Arterial 0.67 Moderate Urban Collector 0.64 Moderate Urban Local 0.88 Serious Rural Minor Arterial 0.71 Serious Rural Major Collector 0.83 Serious Rural Minor Collector 0.59 Serious Rural Local 0.35 Serious Urban Freeway & Expressway 0.67 Serious Urban Minor Arterial 0.67 Serious Urban Collector 0.64 Serious Urban Local 0.88 Note that the controls were applied at the county/roadway class level, and the controls differ by roadway class. No controls were applied to interstate or principal arterial roadways because these road surfaces typically do not have vacuum sweeping. In the excel spreadsheet, the total emissions for all roadway classes were summed to the county level. Therefore, the emissions at the county level can represent several different control efficiency and rule penetration levels and may include both controlled and uncontrolled emissions in the composite value. 23-4 ------- 23.2.5 Meteorological adjustment After controls were applied, emissions were summed to the county level and converted to tons prior to applying the meteorological adjustment. The meteorological adjustment accounts for the reduction in fugitive dust emissions via the impact of precipitation and other meteorological factors over each hour of the year and then averaged to an annual meteorological adjustment factor for each grid cell in each county, aggregated to a single county-level factor. The county-level meteorological adjustment factors were developed by EPA based on the ratio of the unadjusted to meteorology-adjusted county-level emissions from the SMOKE Flat Files. The county-level meteorological adjustment is a scalar between 0 and 1 that is multiplied by the estimated emissions, where lower-values/greater-reductions are typically found in areas with more frequent precipitation. 23.2.6 Improvements/Changes in the 2020 NEI The 2017 NEI used one county-level meteorological adjustment factors for both paved and unpaved roads. For the 2020 NEI, separate county-level meteorological adjustment factors were developed for paved roads and unpaved roads. The adjustment factors, which are updated each inventory cycle based on modeling conducted by EPA, also showed that roads generally contained less residual moisture than the factors used in 2017, and road dust emissions were higher in 2020. 23.2.7 Puerto Rico and Virgin Islands Since insufficient data exists to calculate emissions for the counties in Puerto Rico and the US Virgin Islands, emissions are based on two proxy counties in Florida: Broward (state-county FIPS=12011) for Puerto Rico and Monroe (state-county FIPS=12087) for the US Virgin Islands. The total emissions in tons for these two Florida counties are divided by their respective populations creating a tons per capita emission factor. For each Puerto Rico and US Virgin Island county, the tons per capita emission factor is multiplied by the county population (from the same year as the inventory's activity data) which served as the activity data. In these cases, the throughput (activity data) unit and the emissions denominator unit are "EACH". 23.3 References 1. United States Environmental Protection Agency, Office of Air Quality Planning and Standards. "Compilation of Air Pollutant Emission Factors, AP-42, Fifth Edition, Volume I: Stationary Point and Area Sources, Section 13.2.1, Paved Roads." Research Triangle Park, NC. January 2011. 2. U.S. Department of Transportation, Federal Highway Administration. https://www.fhwa.dot.gov/policyinformation/statistics/2020/. Table HM-51. Office of Highway Policy Information. Washington, DC. September 2022. 3. E.H. Pechan & Associates, Inc. "Phase II Regional Particulate Strategies; Task 4: Particulate Control Technology Characterization," draft report prepared for U.S. Environmental Protection Agency, Office of Policy, Planning and Evaluation. Washington, DC. June 1995. 23-5 ------- United States Office of Air Quality Planning and Standards Publication No. EPA-454/R-23-001w Environmental Protection Air Quality Assessment Division March 2023 Agency Research Triangle Park, NC ------- |