Appendix C.3 

On-Road Mobile Source Emission Inventory 

Documentation 
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On-road Mobile Source Emission Inventory Documentation i 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

TABLE OF CONTENTS 

1.0 INTRODUCTION AND SCOPE ............................................................................................. 1

2.0 OVERALL METHODOLOGY ................................................................................................ 1

2.1 Emission Estimation Approach ........................................................................................... 1

3.0 QUALITY ASSURANCE MEASURES .................................................................................. 2

4.0 DISCUSSION OF ON-ROAD MOBILE SOURCES .............................................................. 3

4.1 Introduction and Scope ........................................................................................................ 3

4.2 MOVES Input Assumptions ................................................................................................ 4

4.2.1 Speed Assumptions ........................................................................................................ 4

4.2.2 Vehicle Age Distribution ............................................................................................. 10

4.2.3 Vehicle Mix Assumptions ............................................................................................ 11

4.2.4 Disaggregating State Specific Information .................................................................. 12

4.2.5 Vehicles/Equipment: On-Road Vehicle Equipment ................................................... 16

4.2.6 Road Type ................................................................................................................... 17

4.2.7 Pollutants and Processes ............................................................................................. 18

4.2.8 Temperature, Relative Humidity and Barometric Pressure Assumptions ................... 18

4.2.9 Source Type Population .............................................................................................. 18

4.2.10 Vehicle Inspection and Maintenance Program Assumptions .................................... 21

4.2.11 Reid Vapor Pressure (RVP) Assumptions ................................................................. 21

4.2.12 Diesel Sulfur Content Assumptions ........................................................................... 22

4.2.13 Fuel (Formulation and Supply) ................................................................................. 22

4.3 VMT Assumptions .............................................................................................................. 22

4.4 Estimated Emissions From Mobile Sources ...................................................................... 25

4.5 Motor Vehicle Emissions Budget for Conformity ............................................................. 26

4.5.1 Transportation Conformity .......................................................................................... 26

4.5.2 Pollutants to be Considered ......................................................................................... 26

4.5.3 Safety Margin ............................................................................................................... 33

4.5.4 Motor Vehicle Emission Budgets ................................................................................ 35

5.0 DATA USED ......................................................................................................................... 39

5.1 North Carolina’s Vehicle Mix ........................................................................................... 39

5.1.1 2008 State Vehicle Mix .............................................................................................. 39

5.1.2 2011 State Vehicle Mix .............................................................................................. 40

5.1.3 2014 State Vehicle Mix .............................................................................................. 41

5.1.4 2017 State Vehicle Mix .............................................................................................. 42

5.1.5 2021 State Vehicle Mix .............................................................................................. 43
On-road Mobile Source Emission Inventory Documentation ii 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.2 Meteorology ........................................................................................................................ 44

5.2.1 Catawba County Temperature and Relative Humidity ................................................ 44

5.2.2 Davidson and Guilford County Temperature and Relative Humidity ......................... 50

LIST OF TABLES 

Table 4.2.1-1 Modeled Area Speeds for Davidson County (miles/hour) ...................................... 5

Table 4.2.1-2 Rural Area Speeds for Davidson County (miles/hour) ............................................ 5

Table 4.2.1-3 Modeled Area Speeds for Guilford County (miles/hour) ........................................ 6

Table 4.2.1-4 Modeled Area Speeds for Catawba County (miles/hour) ........................................ 6

Table 4.2.1-5 Rural Area Speeds for Catawba County (miles/hour) ............................................. 7

Table 4.2.4-1 Mapping of HPMS data to MOBILE6.2 Categories .............................................. 12

Table 4.2.4-2 Calculation of New 2008 Statewide Rural Interstate Vehicle Mix ....................... 14

Table 4.2.4-3 Calculation of 2008 Statewide Rural Interstate Vehicle Mix ................................ 16

Table 4.3-1 Modeled Vehicle Miles Traveled for Davidson County ........................................... 23

Table 4.3-2 Vehicle Miles Traveled for Davidson County Rural Donut Area ............................. 23

Table 4.3-3 Vehicle Miles Traveled for Guilford County ............................................................ 24

Table 4.3-4 Vehicle Miles Traveled for Catawba County Modeled Portion ................................ 24

Table 4.3-5 Vehicle Miles Traveled for Catawba County Rural Donut Area .............................. 25

Table 4.4-1 Emissions by County and year .................................................................................. 25

Table 4.5.3-1 Safety Margin for Hickory PM2.5 Nonattainment Area ......................................... 34

Table 4.5.3-2 Safety Margin for Triad PM2.5 Nonattainment Area ............................................. 34

Table 4.5.4-1 On-Road Mobile Source PM2.5 Emissions ............................................................ 35

Table 4.5.4-2 On-Road Mobile Source NOx Emissions............................................................... 36

Table 4.5.4-3 Catawba County MVEB ........................................................................................ 36

Table 4.5.4-4 Davidson County MVEB ...................................................................................... 36

Table 4.5.4-5 Guilford County MVEB ........................................................................................ 37

Table 4.5.4-6 County Level PM2.5 MVEB Safety Margin for 2011 and 2021 ............................ 37

Table 4.5.4-7 County Level NOx MVEB Safety Margin for 2011 and 2021 .............................. 37

Table 4.5.4-8 New Safety Margins for the Hickory PM2.5 nonattainment area ........................... 38

Table 4.5.4-9 New Safety Margins for the Triad PM2.5 nonattainment area ............................... 38

LIST OF FIGURES 

Figure 4.5.2-2. North Carolina’s 2009 Statewide SO2 Emissions .............................................. 30

Figure 4.5.2-3. Hickory Area 2009 Primary PM2.5 Emissions ..................................................... 31

Figure 4.5.2-4. Catawba County Hourly PM2.5 Emissions ........................................................... 33
On-road Mobile Source Emission Inventory Documentation 1 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

1.0 INTRODUCTION AND SCOPE 

This fine particulate matter (PM2.5) on-road mobile source documentation covers the Hickory 

PM2.5 nonattainment area (Catawba County) and the Greensboro/Winston Salem/High Point 

PM2.5 nonattainment area (referred to as the Triad area and consisting of Davidson and Guilford 

Counties). On-road mobile sources produce nitrogen oxides (NOx), particles less than 2.5 

micrometers in diameter (PM2.5), and sulfur dioxide (SO2), along with a host of other pollutants. 

Emissions of these pollutants are estimated in the mobile source inventory required for the 

maintenance plan. Mobile sources comprise about 74% of the NOx emissions in the Hickory 

and Triad fine particulate matter nonattainment areas. The scope of this document covers only 

the procedures associated with on-road mobile sources. 

2.0 OVERALL METHODOLOGY 

2.1 Emission Estimation Approach 

Mobile source emissions are estimated by the methodologies suggested in the United States 

Environmental Protection Agency (USEPA) documents Emissions Inventory Guidance for 

Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards 

(NAAQS) and Regional Haze Regulations, Policy Guidance on the Use of MOVES2010 for 

State Implementation Plan Development, Transportation Conformity, and Other Purposes (EPA420-B-09-046, December 2009), and Technical Guidance on the Use of MOVES2010 for 

Emission Inventory Preparation in State Implementation Plans and Transportation Conformity 

(EPA-420-B-10-023, April 2010). 

In December 2009, the USEPA released a new model for mobile sources. MOVES (MOtor 

Vehicle Emissions Simulator) is a computer program designed by the USEPA to estimate air 

pollution emissions from mobile sources. MOVES2010 (hereafter referred to as MOVES) 

replaces the USEPA’s previous emissions model for on-road mobile sources, MOBILE6.2. 

MOVES is used to estimate exhaust and evaporative emissions as well as brake and tire wear 

emissions from all types of on-road vehicles. 

Compared to MOBILE6.2, MOVES incorporates substantial new emissions test data and 

accounts for changes in vehicle technology and regulations as well as improved understanding of 

in-use emission levels and the factors that influence them. Also, MOVES has a completely new 

database-centered software framework. 
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Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

There is currently a two year grace period for transportation conformity purposes for use of 

MOVES as the new regulatory model. However, the North Carolina Division of Air Quality 

(NCDAQ) committed to provide supplemental data to the Annual PM2.5 Redesignation 

Demonstration and Maintenance Plan when MOVES was released and approved for regulatory 

purposes. 

The estimation of emissions from mobile sources involves multiplying an activity level by an 

emission factor. Previously this was done using MOBILE6.2 to calculate an emissions factor 

and multiplying it by the vehicle miles travelled (VMT). One important new feature of MOVES is 

the option to calculate emissions either as inventory estimates (total emissions in units of mass) or, 

emission rates (emissions per unit of distance for running emissions or per vehicle for starts, 

extended idle and resting evaporative emissions) in a look-up table format. 

Use of the inventory option simplifies the post-processing of MOVES output compared to 

MOBILE6.2, but it requires VMT and vehicle population data as an input to MOVES. When using 

the emission rates option, VMT and vehicle population are applied during post-processing external to 

MOVES. Either approach can be used to develop emissions estimates for state implementation plans 

(SIPs) and regional conformity analyses. If inventory option is selected, MOVES provides emissions 

estimates as mass, using VMT and vehicle population entered by the user. If emission rate option is 

selected, MOVES provides emission rates as mass per unit of activity. The emission rates option 

produces a look-up table of emission rates that must be post-processed to produce an inventory. The 

NCDAQ is electing to run the model in the inventory mode due to faster model run times and fewer 

post-processing requirements.

The USEPA has performed preliminary comparison of MOVES2010 to MOBILE6.2 using local 

data for several different urban areas, varying the local data used by fleet distribution, fraction of 

light- and heavy-duty VMT, local fuel specifications, meteorology, and other input factors. In 

general, volatile organic carbon (VOC) emissions are lower when using MOVES2010 when 

compared to MOBILE6.2, while NOx and particulate matter (PM) emissions are higher. 

3.0 QUALITY ASSURANCE MEASURES 

The quality assurance (QA) for the highway mobile source category can be broken into two 

components: 1) input files and 2) MOVES outputs/summaries. Each of these components is 

detailed in the paragraphs below. 

After the speed and VMT information is acquired from the North Carolina Department of 

Transportation (NCDOT), the speed information is checked for reasonableness against previous 
On-road Mobile Source Emission Inventory Documentation 3 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

sets of speeds for the areas. Once the speeds are deemed reasonable, the NCDAQ enters the 

speed information into MOVES input files. In addition to the speed information, the user enters 

data to characterize local meteorology, fleet and activity information. All input files are checked 

against a “key” with the original source of the information. This QA step is always performed 

by a person other than the one who generated the input files. If any discrepancies are found, they 

are noted back to the person who generated the input files for correction. 

Once the input files have passed through the QA procedure, MOVES is run to generate 

emissions. 

4.0 DISCUSSION OF ON-ROAD MOBILE SOURCES 

On-road mobile sources produce NOx, PM2.5, and SO2, along with a host of other pollutants. 

Emissions of these three pollutants are estimated in the on-road mobile source inventory for the 

maintenance plan. The objective of the following section is to describe the source category, the 

input files, and the emissions estimation procedures. This section also includes tables 

summarizing the estimated emissions for the projection years by county. 

4.1 Introduction and Scope 

On-road mobile sources are considered as those vehicles that travel on the roadways. On-road 

mobile sources are a major contributor to NOx emissions in North Carolina and a less significant 

contributor to primary PM2.5 and SO2. Emissions from motor vehicles occur throughout the day 

while the vehicle is in motion, at idle, parked, and during refueling. All of these emissions 

processes need to be estimated in order to properly reflect the total emissions from this source 

category. 

On-road mobile source emissions comprise a small percentage of the total fine particulate matter 

emissions for all of North Carolina. Particulate emissions from motor vehicles only occur while 

the vehicle is moving or idling. These emissions are direct tailpipe (from both gas and diesel 

fuel vehicles), sulfate, tire wear, and brake wear. Only direct particulate emissions processes 

will be estimated in order to properly reflect the total fine particulate matter emissions from this 

source category. 

A very important component of the highway mobile emission estimation process is interagency 

consultation. The primary transportation partners involved in the Hickory and Triad 

redesignation interagency consultation process included: NCDOT, USEPA, Federal Highway 

Administration (FHWA), Greensboro Urban Area Municipal Planning Organization (MPO), 
On-road Mobile Source Emission Inventory Documentation 4 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

High Point Urban Area MPO, Piedmont Triad Rural Planning Organization (RPO), and Greater 

Hickory MPO. Specifically the NCDOT was consulted for input data such as speeds and VMT 

for the rural counties where the Hickory and Triad Urban Travel Demand Models (TDMs) did 

not cover. An interagency call was held April 19, 2010 to discuss the need to update the motor 

vehicle emission budgets (MVEBs) for the Greater Hickory and Triad areas. The NCDAQ had 

the data originally provided for the redesignation for the years 2008, 2011, 2014, 2017, and 

2021. The NCDAQ received updated speeds and VMT for the Triad (Davidson and Guilford 

Counties), in February 2009, as well as, updated speeds and VMT for Catawba County from 

NCDOT in April 2009. The NCDAQ discussed the differences anticipated in the emissions by 

running the MOVES model and the possible necessity to update the MVEBs in the 

Redesignation Package before the MOVES model would be required to be used for conformity 

purposes. The interagency partners agreed that the activity data that the NCDAQ had were the 

latest and should be used as inputs to the MOVES model. 

4.2 MOVES Input Assumptions 

Due to the size and the complexity of the MOVES input and output files, the MOVES input files 

and output files will be provided electronically. 

4.2.1 Speed Assumptions 

Vehicle power, speed, and acceleration have a significant effect on vehicle emissions. MOVES 

models those emission effects by assigning activity to specific drive cycles or operating mode 

distributions. The distribution of vehicle hours traveled (VHT) by average speed is used to determine 

an appropriate operating mode distribution. The Average Speed Distribution importer in MOVES 

calls for a speed distribution in VHT in 16 speed bins, by each road type, source type, and hour of the 

day included in the analysis. The methodology used to develop the average speed distribution inputs 

is documented below. 

The speeds for the urban areas covered by a TDM were provided by the MPOs. Piedmont 

Authority for Regional Transportation (PART) provided modeled speeds for the entire county of 

Guilford and the modeled portion of Davidson County for the desired maintenance plan years. 

Speeds for rural areas in Davidson and the urban and rural areas in Catawba were generated by 

NCDOT. Modeled speeds for urban areas of Catawba County were received for the years 2007, 

2015, 2025, and 2035, and interpolated to the years needed. Tables 4.2.1-1 through 4.2.1-5 

provide a summary of the average speeds in miles per hour (mph). 
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Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.2.1-1 Modeled Area Speeds for Davidson County (miles/hour) 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 68 68 68 68 67 

Urban Freeway or Expressway 57 57 56 56 55 

Urban Other Principal Arterial 39 39 38 38 39 

Urban Minor Arterial 40 40 40 40 39 

Urban Collector 42 41 42 42 41 

Urban Local 46 45 45 45 44 

Rural Interstate 69 68 68 68 68 

Rural Other Principal Arterial --- --- --- 35 35 

Rural Minor Arterial 51 51 51 51 50 

Rural Major Collector 43 43 42 42 41 

Rural Minor Collector 49 48 48 48 48 

Rural Local 49 49 48 48 48 

Table 4.2.1-2 Rural Area Speeds for Davidson County (miles/hour) 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 62 63 62 62 62 

Urban Freeway or Expressway 56 56 56 56 56 

Urban Other Principal Arterial 28 29 28 28 29 

Urban Minor Arterial 32 32 32 32 32 

Urban Collector 31 31 31 31 31 

Urban Local 31 31 31 31 31 

Rural Interstate 65 66 65 65 65 

Rural Other Principal Arterial 45 46 45 45 45 

Rural Minor Arterial 44 44 44 44 44 

Rural Major Collector 43 43 43 43 43 

Rural Minor Collector 42 42 42 42 42 

Rural Local 42 42 42 42 42 
On-road Mobile Source Emission Inventory Documentation 6 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.2.1-3 Modeled Area Speeds for Guilford County (miles/hour) 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 55 55 56 56 55 

Urban Freeway or Expressway 51 51 50 50 51 

Urban Other Principal Arterial 39 39 39 39 39 

Urban Minor Arterial 37 37 38 38 38 

Urban Collector 37 37 37 37 37 

Urban Local 34 34 34 34 34 

Rural Interstate 60 59 58 58 57 

Rural Other Principal Arterial 47 48 50 50 49 

Rural Minor Arterial 43 42 44 44 46 

Rural Major Collector 46 46 46 46 45 

Rural Minor Collector 47 47 47 47 46 

Rural Local 43 42 46 46 45 

Table 4.2.1-4 Modeled Area Speeds for Catawba County (miles/hour) 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 60 59 57 55 52 

Urban Freeway or Expressway 46 46 45 45 44 

Urban Other Principal Arterial 34 33 32 31 30 

Urban Minor Arterial 34 33 32 31 30 

Urban Collector 36 35 34 33 32 

Urban Local 38 37 36 35 33 

Rural Interstate 64 63 62 60 56 

Rural Other Principal Arterial 59 59 58 58 57 

Rural Minor Arterial 42 41 40 39 38 

Rural Major Collector 43 43 42 42 41 

Rural Minor Collector 37 36 35 35 34 

Rural Local 42 42 41 41 40 
On-road Mobile Source Emission Inventory Documentation 7 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.2.1-5 Rural Area Speeds for Catawba County (miles/hour) 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 63 63 63 63 63 

Urban Freeway or Expressway 56 56 56 56 56 

Urban Other Principal Arterial 29 29 29 29 29 

Urban Minor Arterial 32 32 32 32 32 

Urban Collector 31 31 31 31 31 

Urban Local 31 31 31 31 31 

Rural Interstate 63 63 63 63 63 

Rural Other Principal Arterial 46 46 46 46 46 

Rural Minor Arterial 44 44 44 44 44 

Rural Major Collector 43 43 43 43 43 

Rural Minor Collector 42 42 42 42 42 

Rural Local 42 42 42 42 42 

MOVES uses four different roadway type categories that are affected by the average speed 

distribution input: rural restricted access, rural unrestricted access, urban restricted access, and 

urban unrestricted access (these road types are discussed in more detail in Section 4.2.6). In 

MOVES, local roadways are included with arterials and collectors in the urban and rural 

unrestricted access roads category. In MOBILE6.2, local roadways were a separate category with 

a fixed speed of 12.9 mph. For MOVES, the USEPA recommends that the average speed 

distribution for local roadway activity be included as part of a weighted distribution of average 

speed across all unrestricted roads along with the distribution of average speeds for arterials and 

connectors. 

When only a single average speed is available for a specific road type and that average speed is 

not identical to the average speed in a particular speed bin, MOVES guidance stipulates that 

users should apply the following formula for creating the appropriate speed distribution among 

two adjacent speed bins. 

The general formula is: 

VHT Fraction A in Speed Bin with closest average speed lower than observed average speed + 

VHT Fraction B in Speed Bin with closest average speed higher that observed average speed = 1 
On-road Mobile Source Emission Inventory Documentation 8 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

VHT Fraction A(low bin) = 1 – [(observed average speed – average speed of lower speed bin) / 

(average speed of higher speed bin – average speed of lower speed bin)] 

VHT Fraction B(high bin) = 1- [(average speed of higher speed bin – observed average speed) / 

(average speed of higher speed bin – average speed of lower speed bin)] 

Or more simply: VHT Fraction B = 1 – VHT fraction A 

The following is an example of applying the above equations. If the single average speed for a 

roadway is 58 miles per hour, the average speed distribution will be split between the 55 and 60 

mph speed bins. The appropriate VHT fractions are found with the following equations: 

VHT fraction A(low bin) = 1 – [(58 mph Avg. Speed – 55 mph (Bin Speed)) / (60 mph (Bin Speed) 

– 55 mph (Bin Speed)] = 0.4 

VHT fraction B(high bin) = 1 – [(60 mph (Bin Speed) – 58 mph Avg. Speed) / (60 mph (Bin Speed) 

– 55 mph (Bin Speed)] = 0.6 

VHT Fraction A(low bin) + VHT Fraction B(high bin) = 1 

 0.4 + 0.6 = 1 

As stated above, MOVES uses only four different roadway types: rural restricted access, rural 

unrestricted access, urban restricted access and urban unrestricted access. This means that the 

speeds for multiple roadway types need to be combined into the appropriate speed bins. To 

create the speed bin fractions for combined roadways the VMT for each road way is used to 

weight the speed bin fraction. For example, below are speeds and VMT for urban restricted 

access road types: 

Road type Speed 

(miles/hour) 

VMT 

(hourly miles) 

Urban Interstate 63 250,000 

Urban Freeway 56 100,000 

The first step is to determine the speed bin fractions for each road type separately. For the urban 

interstate road type, the speed 63 is split between the MOVES speed bins of 60 and 65 as 

described above, which results in the VHT fractions of 0.4 and 0.6 for speed bins 60 and 65, 

respectively. Similarly, the speed for the urban freeway road type (56 miles/hour) is split 
On-road Mobile Source Emission Inventory Documentation 9 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

between the MOVES speed bins of 55 and 60 and results in the VHT fractions of 0.8 and 0.2, 

respectively. 

The next step requires road type VMT to weigh the VHT Fractions so that the final MOVES 

speed bin fractions can be developed. The VHT Fraction, specific to the road type and speed 

bin, are multiplied by the corresponding hourly VMT. These hourly totals are divided by the 

total VMT for that hour for the road type category (in this example, urban restricted access 

includes urban interstate and urban freeway). The following equation is used to calculate the 

combined speed bin fractions: 

Where: 

RT = the HPMS road type 

In this example, the HPMS road types are urban interstate (UI) and urban freeway (UF) and the 

speed bins are 55, 60 and 65. The table below summarizes the speed bin fractions for this 

example. 

HPMS Road Type Speed Bin 55 Speed Bin 60 Speed Bin 65 

Urban Interstate 0.0 0.4 0.6 

Urban Freeway 0.8 0.2 0.0 

Using the equation below, the final MOVES speed bin fractions are calculated for the urban 

restricted access road type. 

VHT(Speed Bin X) = [(VHT Fraction(UI) * hourly VMT(UI)) + (VHT Fraction(UF) * hourly VMT(UF))]

(hourly VMT(UI) + hourly VMT(UF)) 

VHT(Speed Bin 55) = [(0.0 * 250,000) + (0.8 * 100,000)]

(250,000 + 100,000) 

VHT(Speed Bin 55) = 0.2286 

 

VHT(Speed Bin 60) = [(0.4 * 250,000) + (0.2 * 100,000)]

(250,000 + 100,000) 

VHT(Speed Bin 60) = 0.3428 
On-road Mobile Source Emission Inventory Documentation 10 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

VHT(Speed Bin 65) = [(0.6 * 250,000) + (0.0 * 100,000)]

(250,000 + 100,000) 

VHT(Speed Bin 65) = 0.4286 

The sum of the VHT fractions for all speed bins within a road type category must add up to 1.0. 

The hourly VHT fractions by speed bin and road type are then processed through a MOVES 

supplied converter to develop the speed distribution file by hour and road type. 

4.2.2 Vehicle Age Distribution 

The age distribution of vehicle fleets can vary significantly from area to area. Fleets with a 

higher percentage of older vehicles will have higher emissions for two reasons. Older vehicles 

have typically been driven more miles and have experienced more deterioration in emission 

control systems. Additionally, a higher percentage of older vehicles also implies that there are 

more vehicles in the fleet that do not meet newer, more stringent emissions standards. Surveys of 

registration data indicate considerable local variability in vehicle age distributions. 

For SIP and conformity purposes, the USEPA recommends and encourages states to develop 

local age distributions. The MOVES model categorizes the vehicle fleet into different vehicle 

classes and more model years than MOBILE6.2. A typical vehicle fleet includes a mix of 

vehicles of different ages. MOVES covers a 31 year range of vehicle ages, with vehicles 30 years 

and older grouped together. MOVES allows the user to specify the fraction of vehicles in each of 

30 vehicle ages for each of the 13 source types in the model. 

Local age distributions can be estimated from local vehicle registration data. The vehicle age 

distribution comes from annual registration data for North Carolina from the NCDOT. For this 

analysis, the age distribution was generated based on 2008 data, the latest available count data at 

the time. The NCDOT provided the data based on the number of vehicle types per year from 

1975 through 2008. The data obtained from the NCDOT has the vehicles greater than 25 years 

old combined and included as the 25th model year. Additionally, the NCDOT data has the 

vehicle count information provided for nine vehicle types; light duty gas vehicles (LDGV), light 

duty diesel vehicles (LDDV), light duty gas trucks 1 (LDGT1), light duty gas trucks 2 (LDGT2), 

light duty diesel trucks 1 (LDDT1), light duty diesel trucks 2 (LDDT2), heavy duty gas vehicles 

(HDGV), heavy duty diesel vehicles (HDDV) and motorcycles (MC). LDDT1 and LDDT2 are 

combined and labeled as light duty diesel trucks (LDDT). Since MOVES categorizes the vehicle 

fleet into different vehicle classes and more model years, the USEPA has created data converters 
On-road Mobile Source Emission Inventory Documentation 11 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

that take registration distribution input files created for MOBILE6.2 and converts them to the 

appropriate age distribution input tables for MOVES. 

4.2.3 Vehicle Mix Assumptions 

Vehicle mix or VMT mix is used by MOVES to convert annual VMT to VMT by HPMS class, 

VMT fractions by hour, and VMT by road type distribution. The vehicle mix is developed by 

the same method used in MOBILE6.2, as outlined below. The resulting file is then used in a 

MOVES supplied converter to develop the VMT by HPMS class, VMT fractions by hour, and 

VMT by road type distribution. 

The vehicle mix refers to the percentage of different vehicle types on each of the 12 FHWA road 

types. These road types are listed above in the speed assumptions section. It is critical for 

estimating on-road mobile source emissions in an area to use data that accurately reflects the 

vehicles types traveling on each of these different road types. 

In August 2004, the USEPA released the guidance document EPA420-R-04-013, Technical 

Guidance on the Use of MOBILE6.2 for Emission Inventory Preparation, which outlines how to 

convert the Highway Performance Monitoring System (HPMS) traffic count data to MOBILE6.2 

vehicle mix data. Outlined below is the methodology used to convert the 13 HPMS vehicle 

types count data reported to FHWA and generate a state specific vehicle mix. 

The North Carolina HPMS data used to generate the new statewide vehicle mix was based on 

2008 data counts. This is the latest available statewide count information at the time of the 

modeling. Table 4.2.3-1 shows the percent of vehicles per vehicle type for each of the 12 road 

classes. 

Table 4.2.3-1 2008 North Carolina HPMS Data 
On-road Mobile Source Emission Inventory Documentation 12 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

4.2.4 Disaggregating State Specific Information 

Section 4.1.5 of Technical Guidance on the Use of MOBILE6.2 for Emission Inventory 

Preparation, illustrates how to map the HPMS statewide vehicle data to general MOBILE6.2 

vehicle categories. This mapping is outlined in Table 4.2.4-1 below: 

Table 4.2.4-1 Mapping of HPMS data to MOBILE6.2 Categories 

HPMS Category General Category 

Motorcycle Motorcycle (MC) 

Passenger Car Passenger Car (LDV) 

Other 2-Axel, 4-Tire Vehicles Light Truck (LDT) 

Busses Bus (HDB) 

All Other Trucks: 

 Single unit, 2-axel, 6-tire 

 Single unit, 3-axel 

 Single unit, 4 or more axel 

 Single trailer, 4 or fewer axel 

 Single trailer, 5-axel 

 Single trailer, 6 or more axel 

 Multi-trailer, 5 or fewer axel 

 Multi-trailer, 6-axel 

 Multi-trailer, 7 or more axel 

Heavy Duty Truck (HDV) 

The HPMS data in Table 4.2.3-1 was grouped into these five general categories for each road 

type. In order to expand the five general categories to the 16 vehicle types used in MOBILE6.2, 

the national average VMT fractions by each vehicle class were used. The 2008 fractions were 

used since the state specific data is from 2008. The national average data was obtained from 

Table 4.1.2 in Technical Guidance on the Use of MOBILE6.2 for Emission Inventory 

Preparation. An example for rural interstates is illustrated below: 

From Table 4.2.3-1 above: 

 Passenger Cars = 60.13% 5 axel Trailer = 17.65% 

 Pickup Trucks = 13.72% 6 axel Trailer = 0.66% 

 Bus = 1.04% 5 axel Multi Trailer = 0.51% 

 2 axel Trucks = 2.86% 6 axel Multi Trailer = 0.23% 

 3 axel Trucks = 0.75% 7 axel Multi Trailer = 0.15% 

 4 axel Trucks = 0.05% Motorcycles = 0.38% 

 4 axel Trailer = 1.86% 
On-road Mobile Source Emission Inventory Documentation 13 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Therefore, the five general categories are: 

Motorcycles = 0.38% 

Light Duty Vehicles = 60.13% 

Light Duty Trucks = 13.72% 

Heavy Duty Buses = 1.04% 

Heavy Duty Vehicles = 24.73% 

From Table 4.1.2 in Technical Guidance on the Use of MOBILE6.2 for Emission Inventory 

Preparation, the 2008 national average vehicle mix for light duty trucks, buses and heavy duty 

trucks are: 

 Light Duty Trucks Heavy Duty Trucks 

LDT1 = 0.0846 

LDT2 = 0.2817 

LDT3 = 0.0868 

LDT4 = 0.0399 

Total = 0.4930 

 Buses 

Using the methodology described in Section 4.1.5 in Technical Guidance on the Use of 

MOBILE6.2 for Emission Inventory Preparation the new 2008 North Carolina statewide mix 

was developed. The basic formula for developing the mix is shown below, 

 Vehicle Type = (2008 M6.2 fraction for vehicle) X (2008 State total for group) . 

 (2008 M6.2 total for subcategory) 

Table 4.2.4-2 displays the calculation for each vehicle type for the 2008 rural interstate vehicle 

mix. 

HDV2B = 0.0388 

HDV3 = 0.0038 

HDV4 = 0.0031 

HDV5 = 0.0024 

HDV6 = 0.0087 

HDV7 = 0.0102 

HDV8A = 0.0111 

HDV8B = 0.0397 

Total = 0.1178 

HDBS = 0.0020 

HDBT = 0.0009 

Total = 0.0029 
On-road Mobile Source Emission Inventory Documentation 14 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.2.4-2 Calculation of New 2008 Statewide Rural Interstate Vehicle Mix 

Vehicle 

Type Calculation New 2008 Mix 

LDV = LDV = 0.6013 

MC = MC = 0.0038 

Light Duty Trucks 

LDT1 = 0.0846 x (0.1372/0.4930) = 0.0235 

LDT2 = 0.2817 x (0.1372/0.4930) = 0.0784 

LDT3 = 0.0868 x (0.1372/0.4930) = 0.0242 

LDT4 = 0.0399 x (0.1372/0.4930) = 0.0111 

Heavy Duty Vehicles 

HDV2B = 0.0388 x (0.2473/0.1178) = 0.0815 

HDV3 = 0.0038 x (0.2473/0.1178) = 0.0080 

HDV4 = 0.0031 x (0.2473/0.1178) = 0.0065 

HDV5 = 0.0024 x (0.2473/0.1178) = 0.0050 

HDV6 = 0.0087 x (0.2473/0.1178) = 0.0183 

HDV7 = 0.0102 x (0.2473/0.1178) = 0.0214 

HDV8A = 0.0111 x (0.2473/0.1178) = 0.0233 

HDV8B = 0.0397 x (0.2473/0.1178) = 0.0833 

Buses 

HDBS = 0.0020 x (0.0104/0.0029) = 0.0072 

HDBT = 0.0009 x (0.0104/0.0029) = 0.0032 

2008, 2011, 2014, 2017 and 2021 Statewide Vehicle Mix

Once the 2008 new vehicle mix was generated, the other years were created using the 

methodology described in Section 4.1.4 in Technical Guidance on the Use of MOBILE6.2 for 

Emission Inventory Preparation. This method grouped light duty vehicles, light duty trucks and 

motorcycles together and heavy duty buses, heavy duty trucks and heavy duty vehicles together. 

The combined percentages for these groupings are listed below. 

 Light Duty Vehicles = 74.23% 

 Heavy Duty Vehicles = 25.77% 
On-road Mobile Source Emission Inventory Documentation 15 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

The MOBILE6.2 vehicle mix fractions for the year being developed were obtained from 

Table 4.1.2 in Technical Guidance on the Use of MOBILE6.2 for Emission Inventory 

Preparation. The MOBILE6.2 vehicle fractions for 2008 are listed below. 

 Light Duty Vehicles Heavy Duty Vehicles 

 

The North Carolina 2008 vehicle mix was normalized to the MOBILE6.2 fractions using the 

following formula: 

 Vehicle Type = (2008 M6 fraction for vehicle) X (2008 State total for group)

 (2008 M6 total for group) 

Table 4.2.4-3 below displays the calculations used to generate the 2008 North Carolina vehicle 

mix for rural interstate. 

LDV = 0.3807 

LDT1 = 0.0846 

LDT2 = 0.2817 

LDT3 = 0.0868 

LDT4 = 0.0399 

MC = 0.0056 

Total = 0.8793 

HDV2B = 0.0388 

HDV3 = 0.0038 

HDV4 = 0.0031 

HDV5 = 0.0024 

HDV6 = 0.0087 

HDV7 = 0.0102 

HDV8A = 0.0111 

HDV8B = 0.0397 

HDBS = 0.0020 

HDBT = 0.0009 

Total = 0.1207 
On-road Mobile Source Emission Inventory Documentation 16 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.2.4-3 Calculation of 2008 Statewide Rural Interstate Vehicle Mix 

Vehicle 

Type Calculation 2008 State Mix 

Light Duty Vehicles 

LDV = 0.3807 x (0.7386/0.8737) = 0.3219 

LDT1 = 0.0846 x (0.7386/0.8737) = 0.0715 

LDT2 = 0.2817 x (0.7386/0.8737) = 0.2381 

LDT3 = 0.0868 x (0.7386/0.8737) = 0.0734 

LDT4 = 0.0399 x (0.7386/0.8737) = 0.0337 

MC = 0.0038 

Heavy Duty Vehicles 

HDV2B = 0.0388 x (0.2472/0.1178) = 0.0814 

HDV3 = 0.0038 x (0. 2472/0.1178) = 0.0080 

HDV4 = 0.0031 x (0. 2472/0.1178) = 0.0065 

HDV5 = 0.0024 x (0. 2472/0.1178) = 0.0050 

HDV6 = 0.0087 x (0. 2472/0.1178) = 0.0183 

HDV7 = 0.0102 x (0. 2472/0.1178) = 0.0214 

HDV8A = 0.0111 x (0. 2472/0.1178) = 0.0233 

HDV8B = 0.0397 x (0. 2472/0.1178) = 0.0833 

HDBS = 0.0020 x (0.0104/0.0029) = 0.0072 

HDBT = 0.0009 x (0.0104/0.0029) = 0.0032 

This method was used to generate all of the future year vehicle mixes that were needed to 

compute the emission factors. The North Carolina transportation partners consider the statewide 

vehicle mix to be the best representation of the vehicle population in the Hickory and Triad 

nonattainment area. The vehicle mixes for all years can be found in Section 5.1 of this appendix. 

As stated earlier in this section, vehicle mix or VMT mix is used in MOVES converters to 

develop VMT by HPMS class, VMT fractions by hour, and VMT by road type distribution, 

which are inputs to the model. 

4.2.5 Vehicles/Equipment: On-Road Vehicle Equipment 

The Vehicles/Equipment menu item and panel is used to specify the vehicle types that are 

included in the MOVES run. MOVES allows the user to select from among 13 “source use 
On-road Mobile Source Emission Inventory Documentation 17 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

types” (the terminology that MOVES uses to describe vehicle types), and four different fuel 

types (gasoline, diesel, compressed natural gas (CNG), and electricity). 

For SIP and regional conformity analyses, users must select the appropriate fuel and vehicle type 

combinations in the On Road Vehicle Equipment panel to reflect the full range of vehicles that 

will operate in the county. For this analysis all valid diesel, gasoline, and CNG (only transit 

buses) vehicle and fuel combinations were selected. 

4.2.6 Road Type 

The Road Type Panel is used to define the types of roads that are included in the run. MOVES 

defines five different Road Types: 

• Off-Network (roadtype 1) – all locations where the predominant activity is vehicle starts, 

parking and idling (parking lots, truck stops, rest areas, freight or bus terminals) 

• Rural Restricted Access (2) – rural highways that can only be accessed by an on-ramp 

• Rural Unrestricted Access (3) – all other rural roads (arterials, connectors, and local 

streets) 

• Urban Restricted Access (4) – urban highways or freeways that can only be accessed by 

an on-ramp 

• Urban Unrestricted Access (5) – all other urban roads (arterials, connectors, and local 

streets) 

Users should select the road types present in the area being analyzed. The determination of rural 

or urban road types should be based on the HPMS classification of the roads in the county being 

analyzed. 

The NCDAQ followed the USEPA guidance that states that all SIP and regional conformity 

analyses must include the Off-Network road type in order to account for emissions from vehicle 

starts, extended idle activity, and evaporative emissions (for hydrocarbons). The Off-Network 

road type is automatically selected when start or extended idle pollutant processes are chosen and 

must be selected for all evaporative emissions to be quantified. Off-Network activity in MOVES 

is primarily determined by the Source Type Population input, which is described in Section 4.2.9 

of this document. Some evaporative emissions are estimated on roadways (i.e., roadtypes 2, 3, 4, 

and 5) to account for evaporative emissions that occur when vehicles are driving. All roads types 

are automatically selected when Refueling emission processes are selected. 
On-road Mobile Source Emission Inventory Documentation 18 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

MOVES uses Road Type to assign default drive cycles to activity on road types 2, 3, 4, and 5. 

For example, for unrestricted access road types, MOVES uses drive cycles that assume stop and 

go driving, including multiple accelerations, decelerations, and short periods of idling. For 

restricted access road types, MOVES uses drive cycles that include a higher fraction of cruise 

activity with less time spent accelerating or idling, although some ramp activity is also included. 

4.2.7 Pollutants and Processes 

In MOVES, pollutant refers to particular types of pollutants or precursors of the pollutant, such as 

PM or NOx, while process refers to the mechanism by which emissions are created, such as running 

exhaust or start exhaust. Users must select all processes associated with a particular pollutant in order 

to account for all emissions of that pollutant. For example, there are 11 separate pollutant processes 

in MOVES for hydrocarbon emissions; all 11 must be selected when estimating hydrocarbon 

emissions for SIPs or regional conformity analyses. For this maintenance plan, the pollutants under 

consideration were NOx, PM2.5, and SO2. 

4.2.8 Temperature, Relative Humidity and Barometric Pressure Assumptions 

Local temperature and humidity data are required inputs for SIP and regional conformity analyses 

with MOVES. Ambient temperature is a key factor in estimating emission rates for on-road vehicles 

with substantial effects on most pollutant processes. Relative humidity is also important for 

estimating NOx emissions from motor vehicles. MOVES requires a temperature (in degrees 

Fahrenheit) and relative humidity (in percent – 0 to 100 scale) for each hour selected in the Run 

Spec. For example, MOVES requires a 24-hour temperature and humidity profile to model a full day 

of emissions on an hourly basis. For mobile source emission estimates, the NCDAQ used 2008 

monthly averages for the 24-hour temperature profile from the Hickory Airport for Catawba 

County and the Triad Regional Airport for Davidson and Guilford Counties. Data were obtained 

by the NCDAQ meteorologists from North Carolina State Climate Retrieval and Observations 

Network of the Southeast Database (CRONOS). The temperature and relative humidity profiles 

as presented in the MOVES input files are listed in Section 5.2 for each month. 

4.2.9 Source Type Population 

Source type (i.e., vehicle type) population is used by MOVES to calculate start and evaporative 

emissions. In MOBILE6.2, starts and evaporative emissions were calculated as emission factors 

in grams per mile. As a result, start and evaporative emissions were related to VMT. However, 

the relationship between VMT and vehicle starts or evaporative emissions is not always 

consistent. Chained trips may involve multiple starts with relatively low VMT. Evaporative 

emissions depend more on how long a vehicle is parked than how many miles it is driven. In 

MOVES, start and resting evaporative emissions are related to the population of vehicles in an 
On-road Mobile Source Emission Inventory Documentation 19 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

area. Since vehicle type population directly determines start and evaporative emission, users 

must develop local data for this input. 

MOVES uses a vehicle classification system based on the way vehicles are classified in the 

Federal Highway Administration’s HPMS rather than on the way they are classified in the 

USEPA emissions regulations; thus making it easier for users to develop local data for MOVES. 

MOVES categorizes vehicles into 13 source types, which are subsets of 6 HPMS vehicle types in 

MOVES, as shown in the crosswalk in Table 4.2.9-1. The USEPA believes that states should be 

able to develop population data for many of these source type categories from state motor 

vehicle registration data (e.g., motorcycles, passenger cars, passenger trucks, light commercial 

trucks) and from local transit agencies, school districts, bus companies, and refuse haulers 

(intercity, transit, and school buses, and refuse trucks). The NCDOT supplied the NCDAQ with 

source population data as described in the following section. 

Table 4.2.9-1 

MOVES Source Types and HPMS Vehicle Types 

Source Type ID Source Types HPMS Vehicle 

Type ID 

HPMS Vehicle Type 

11 Motorcycle 10 Motorcycles 

21 Passenger Car 20 Passenger Cars 

31 Passenger Truck 30 Other 2 axle-4 tire vehicles 

32 Light Commercial Truck 30 Other 2 axle-4 tire vehicles 

41 Intercity Bus 40 Buses 

42 Transit Bus 40 Buses 

43 School Bus 40 Buses 

51 Refuse Truck 50 Single Unit Trucks 

52 Single Unit Short-haul Truck 50 Single Unit Trucks 

53 Single Unit Long-haul Truck 50 Single Unit Trucks 

54 Motor Home 50 Single Unit Trucks 

61 Combination Short-haul Truck 60 Combination Trucks 

62 Combination Long-haul Truck 60 Combination Trucks 

Source Type Population – Local Data

MOVES uses allocation factors to distribute emissions and activity (such as vehicle type 

populations) to individual counties. The NCDAQ is committed to using representative local data 

which will over ride MOVES default values through the County Data Manager. This decision 

was based on the fact that default allocation factors used in MOVES are derived from the 

VMT. Since the allocations are based on VMT, the vehicle populations allocated to counties are 

proportional to the VMT being allocated to that county. The NCDAQ corresponded with 
On-road Mobile Source Emission Inventory Documentation 20 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

USEPA Office of Transportation and Air Quality (OTAQ) to arrive at an acceptable method to 

allocate current year as well as to project future year vehicle populations to source type 

populations. The NCDAQ believes that using MOVES default vehicle population to estimate a 

fraction is the best method of taking state specific vehicle registration data and allocating county 

total vehicles to specific vehicle source types. 

MOVES categorize vehicles into 13 source types, which are subsets of 6 HPMS vehicle types. 

Presently the NCDAQ is unable to develop county source type population data for many of these 

source type categories based on how the NCDOT collects vehicle registration data. The latest 

vehicle registration data broken down by county and towns is available by January of each year. 

Because the vehicle types database available from the NCDOT differs from what MOVES2010 

expects, the NCDAQ relies on MOVES default fractions and applies these fractions to the 

county total vehicle population minus trailers. It is assumed that trailers do not have engines and 

do not generate VMT. 

For future year MOVES runs, the NCDAQ needed to be able to grow the vehicle population 

reflective of the county of interest. From FHWA Highway Statistics graph of Licensed Drivers, 

Vehicle Registrations, and Resident Population (Figure 4.2.9-1), the NCDAQ has determined 

that growth in human population is a better indicator of growth in vehicle ownership as 

compared to VMT growth. 

Figure 4.2.9-1 Federal Highway Association Statistics Graph 

In order to forecast future year vehicle population and disaggregate to the appropriate source 

type, a reliable source of county population is needed. The North Carolina Office of State Budget 

and Management (OSBM) coordinates with the Census Bureau in the Federal State Cooperative 
On-road Mobile Source Emission Inventory Documentation 21 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Program for population estimates for all state government data, with special emphasis on a 

consistent set of population projections. On the OSBM website are annual certified county 

population estimates which account for births, deaths and natural growth representing a net 

migration populous on the county level. 

Population data is updated annually in May and certified by September for the previous year’s 

data. Projected annual county population estimates are available to adjust future year county 

vehicle populations as needed. The USEPA has indicated that using human population growth as 

a surrogate to project vehicle population growth is an acceptable option. An example of how a 

2008 vehicle population would be grown to 2011 based on this surrogate of projected county 

population follows: 

Vehicle Pop 2011 = Vehicle Pop 2008 * (Human Pop 2011/ Human Pop 2008)

4.2.10 Vehicle Inspection and Maintenance Program Assumptions 

In 2002, North Carolina implemented a new vehicle emissions inspection program referred to as 

onboard diagnostics (OBDII). This program covers all light duty gasoline powered vehicles that 

are model year 1996 and newer. The program was initially implemented in 9 counties and was 

expanded to include a total of 48 counties between July 2002 and January 2006. Guilford 

County was phased in July 2002. Davidson and Catawba Counties were phased-in July 1, 2003. 

Inspection and maintenance programs continue to be important local control programs in many 

nonattainment areas. MOVES has simplified I/M program inputs compared to MOBILE6.2, but 

it includes the capability of modeling all the aspects of an I/M program that have a significant 

impact on vehicle emissions. The USEPA recommends that users modeling an existing I/M 

program in MOVES begin by examining the default I/M program description included in 

MOVES for the particular county in question. The NCDAQ modified the default data in 

MOVES to reflect county specific compliance factors. 

4.2.11 Reid Vapor Pressure (RVP) Assumptions 

RVP reflects a gasoline’s volatility. During the winter months an RVP of 15.0 pounds per 

square inch (psi) is allowable. As ambient air temperatures increase, so does the volatility of 

gasoline. Lower RVP leads to lower VOC emissions from gasoline handling and lowers vapor 

losses from motor vehicles. An RVP of 9.0 psi is required during May through September for 

Catawba County. An RVP of 9.0 psi is required for Davidson and Guilford Counties in May, 

but further reduces to an RVP of 7.8 psi for June through September. 
On-road Mobile Source Emission Inventory Documentation 22 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

4.2.12 Diesel Sulfur Content Assumptions 

The diesel fuel sulfur content is required in MOVES to generate PM2.5 emissions because the 

amount of sulfur in diesel fuel directly correlates to sulfate particulate emissions. For the 

MVEBs calculation, the USEPA recommends a diesel fuel sulfur content of 43 parts per million 

(ppm) for the period June 2006 through May 2010 and 11 ppm for June 2010 and beyond, for all 

of the nonattainment counties. The USEPA’s OTAQ was contacted at the time of this submission 

to verify that there was no update to this guidance. 

4.2.13 Fuel (Formulation and Supply) 

In general, users should first review the MOVES default fuel formulation and fuel supply data, 

and then make changes only where local volumetric fuel property information is available. The 

lone exception to this guidance is in the case of RVP where a user should change the value to 

reflect the regulatory requirements and differences between ethanol- and non-ethanol blended 

gasolines. The current version of MOVES does not allow the user to create new fuel 

identification numbers. Thus, per current The USEPA guidance, the NCDAQ edited the default 

fuel supply tables for the individual counties to reflect the county-specific RVP data.

4.3 VMT Assumptions 

As input, MOVES requires annual VMT by HPMS vehicle class. The USEPA has created a tool 

that allows users to input average annual VMT as well as monthly and weekend day adjustment 

factors to create the annual VMT by HPMS class and appropriate monthly and daily adjustments 

needed by MOVES. The USEPA has also created a set of software tools that can import VMT 

tables by MOBILE6.2 vehicle types (either 8, 12, 16, or 28 MOBILE6.2 vehicle types) and 

facility types, as well as MOBILE6.2 hourly VMT fractions, VMT mix, and ramp fractions and 

convert these to the equivalent MOVES tables of VMT by HPMS class, VMT fractions by hour, 

and road type distribution. 

Mapping MOBILE6.2 vehicle types to their equivalent MOVES source types is a complex 

process. The USEPA strongly encourages states to use the converter tools to create the 

appropriate MOVES input tables from MOBILE6.2 data to avoid errors. 

The modeled and non-modeled VMT for the Triad nonattainment area was provided by PART 

on February 11, 2009 for the years 2008, 2011, 2014, 2017, and in September 2009 for the year 

2021. The non-modeled VMT for the Hickory nonattainment area was provided by the NCDOT 

in September 2009 for the years 2008, 2011, 2015, 2020, and 2025, which were interpolated to 

the required years. The modeled VMT for Catawba County were received for the years 2007, 
On-road Mobile Source Emission Inventory Documentation 23 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

2015, 2020, and 2025 and interpolated to the years needed. Tables 4.3-1 through 4.3-5 list the 

VMT used in the MVEBs calculations. 

Table 4.3-1 Modeled Vehicle Miles Traveled for Davidson County 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 395,808 427,523 454,579 482,342 520,791 

Urban Freeway or Expressway 410,216 436,626 489,844 529,960 566,161 

Urban Other Principal Arterial 400,851 417,566 424,786 445,799 485,302 

Urban Minor Arterial 313,228 333,766 349,383 369,146 399,106 

Urban Collector 174,365 188,452 204,905 216,695 228,296 

Urban Local 263,573 282,255 299,328 314,619 334,105 

Rural Interstate 205,714 221,276 236,619 251,896 272,214 

Rural Other Principal Arterial 0 0 0 301 350 

Rural Minor Arterial 210,241 224,000 239,192 266,365 310,129 

Rural Major Collector 164,069 175,155 185,178 195,299 209,788 

Rural Minor Collector 134,626 144,647 154,644 161,725 169,253 

Rural Local 278,885 301,554 319,434 331,683 346,180 

Table 4.3-2 Vehicle Miles Traveled for Davidson County Rural Donut Area 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 342,756 364,745 374,943 385,141 398,738 

Urban Freeway or Expressway 195,218 205,614 211,362 217,111 224,776 

Urban Other Principal Arterial 271,728 284,492 292,446 300,400 311,005 

Urban Minor Arterial 246,395 254,965 262,094 269,222 278,727 

Urban Collector 94,146 107,235 110,233 113,232 117,229 

Urban Local 96,153 98,562 101,318 104,074 107,748 

Rural Interstate 255,299 251,587 258,621 265,655 275,034 

Rural Other Principal Arterial 152,576 149,062 153,229 157,397 162,954 

Rural Minor Arterial 198,073 198,673 204,228 209,783 217,189 

Rural Major Collector 241,204 238,551 245,220 251,890 260,783 

Rural Minor Collector 160,589 165,660 170,292 174,924 181,099 

Rural Local 98,912 98,757 101,518 104,280 107,961 
On-road Mobile Source Emission Inventory Documentation 24 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.3-3 Vehicle Miles Traveled for Guilford County 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 3,985,564 4,419,157 4,865,961 5,227,576 5,686,133

Urban Freeway or Expressway 2,251,352 2,452,593 2,613,197 2,905,078 3,399,412

Urban Other Principal Arterial 2,368,151 2,477,254 2,591,662 2,679,083 2,770,030

Urban Minor Arterial 2,727,044 2,837,423 3,012,805 3,147,788 3,280,571

Urban Collector 1,368,123 1,452,017 1,570,260 1,645,148 1,700,307

Urban Local 780,183 815,646 847,770 878,533 917,755

Rural Interstate 989,050 1,090,492 1,229,196 1,351,896 1,492,538

Rural Other Principal Arterial 513,834 545,289 546,548 567,373 605,086

Rural Minor Arterial 244,663 273,514 278,683 287,233 304,790

Rural Major Collector 776,249 838,619 898,783 941,639 993,028

Rural Minor Collector 360,879 393,534 420,122 448,880 491,674

Rural Local 411,379 435,206 655,193 721,391 643,883

Table 4.3-4 Vehicle Miles Traveled for Catawba County Modeled Portion 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 1,082,650 1,173,558 1,264,465 1,343,145 1,439,900 

Urban Freeway or Expressway 326,299 355,400 384,500 413,800 453,001 

Urban Other Principal Arterial 875,547 924,218 972,889 1,020,227 1,082,454 

Urban Minor Arterial 922,232 978,471 1,034,710 1,084,007 1,145,109 

Urban Collector 296,562 321,947 347,332 369,591 397,186 

Urban Local 249,239 279,431 309,622 335,319 366,584 

Rural Interstate 55,519 60,555 65,591 70,918 78,214 

Rural Other Principal Arterial 203,044 223,934 244,824 266,142 294,853 

Rural Minor Arterial 116,496 127,525 138,554 151,696 170,628 

Rural Major Collector 97,859 108,994 120,128 130,182 142,869 

Rural Minor Collector 206,017 227,192 248,367 268,052 293,307 

Rural Local 83,014 91,622 100,230 108,227 118,484 
On-road Mobile Source Emission Inventory Documentation 25 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.3-5 Vehicle Miles Traveled for Catawba County Rural Donut Area 

Functional Class 2008 2011 2014 2017 2021 

Urban Interstate 121,399 130,012 135,296 140,580 147,625 

Urban Freeway or Expressway 48,073 51,483 53,576 55,668 58,458 

Urban Other Principal Arterial 134,146 143,663 149,502 155,341 163,126 

Urban Minor Arterial 103,768 111,130 115,647 120,163 126,185 

Urban Collector 28,738 30,777 32,027 33,278 34,946 

Urban Local 93,964 100,630 104,720 108,810 114,263 

Rural Interstate 16,696 17,880 18,607 19,334 20,303 

Rural Other Principal Arterial 35,762 38,299 39,855 41,412 43,487 

Rural Minor Arterial 53,291 57,072 75,073 82,619 85,712 

Rural Major Collector 26,637 28,527 29,686 30,846 32,392 

Rural Minor Collector 49,311 52,810 54,956 57,102 59,964 

Rural Local 27,521 29,474 30,671 31,869 33,466 

4.4 Estimated Emissions From Mobile Sources 

Using the inventory approach in the MOVES model gives a summary of emissions in tons per 

year, by county. Table 4.4-1 summarizes NOx, PM2.5, and SO2 emissions, respectively. 

Table 4.4-1 Emissions by County and year 

County\Year 2008 2011 2014 2017 2021 

NOx Emissions (tons per year) 

Hickory Area 

 Catawba 4,982 4,005 3,240 2,591 2,054 

Triad Area 

 Davidson 5,267 4,095 3,227 2,536 1,974 

 Guilford 14,499 11,157 8,882 7,143 5,796 

 Triad Total 19,766 15,252 12,109 9,679 7,770 
On-road Mobile Source Emission Inventory Documentation 26 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.4-1 Emissions by County and year (Continued) 

County\Year 2008 2011 2014 2017 2021 

 

SO2 Emissions (tons per year) 

Hickory Area 

 Catawba 35 20 18 19 20 

Triad Area 

 Davidson 36 19 17 18 18 

 Guilford 111 62 55 59 63 

 Triad Total 147 81 72 77 81 

 

PM2.5 Emissions (tons per year) 

Hickory Area 

 Catawba 166 127 107 89 73 

Triad Area 

 Davidson 169 121 97 77 60 

 Guilford 465 330 272 221 183 

 Triad Total 634 451 369 298 243 

4.5 Motor Vehicle Emissions Budget for Conformity 

4.5.1 Transportation Conformity 

The purpose of transportation conformity is to ensure that Federal transportation actions 

occurring in a nonattainment area do not hinder the area from attaining and/or maintaining the 

annual PM2.5 standard. This means that the level of emissions estimated by the NCDOT or the 

MPOs for the Transportation Improvement Program and Long Range Transportation Plan must 

not exceed the MVEBs as defined in this maintenance plan. 

4.5.2 Pollutants to be Considered 

40 CFR 93.119(f)(7) through (10) identifies the pollutants for PM2.5 that regional emissions 

analysis needs to be performed for transportation conformity purposes. These parts of the rule 

are listed below: 
On-road Mobile Source Emission Inventory Documentation 27 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

§119(f)(7) – PM2.5 in PM2.5 areas; 

§119(f)(8) – Reentrained road dust in PM2.5 areas only if the EPA [Environmental 

Protection Agency] Regional Administrator or the director of the State air agency 

has made a finding that emissions from reentrained road dust within the area are 

a significant contributor to the PM2.5 nonattainment problem and has so notified 

the MPO and DOT [Department of Transportation]; 

§119(f)(9) – NOx [nitrogen oxides] in PM2.5 areas, unless the EPA Regional 

Administrator and the director of the State air agency have made a finding that 

emissions of NOx from within the area are not a significant contributor to the 

PM2.5 nonattainment problem and has so notified the MPO and DOT; and 

§119(f)(10) – VOC, SO2 and/or ammonia in PM2.5 areas if the EPA Regional 

Administrator or the director of the State air agency has made a finding that any 

of such precursor emissions from within the area are a significant contributor to 

the PM2.5 nonattainment problem and has so notified the MPO and DOT. 

Only primary, or direct PM2.5, tailpipe emissions must be considered for transportation 

conformity regional emissions analysis. The other precursor pollutants and reentrained road dust 

only need to be considered if the State air agency and/or the USEPA has deemed the pollutant as 

a significant contributor to the PM2.5 nonattainment problem. The following sections discuss the 

significance of the precursor pollutants and reentrained road dust to the PM2.5 nonattainment 

problem. 

Precursor Pollutants NOx, VOC, and Ammonia 

The PM2.5 precursor NOx is presumed to be a significant contributor to the PM2.5 nonattainment 

problem by the USEPA. The NCDAQ has determined that NOx is a relatively minor contributor 

to the PM2.5 concentrations in North Carolina. However, the NCDAQ is not asserting that NOx 

is an insignificant precursor for the 1997 PM2.5 standard. Therefore, the NCDAQ will establish 

county level MVEBs for NOx for all three PM2.5 nonattainment counties. 

For the purpose of this attainment demonstration, VOC and ammonia are presumed to be 

insignificant contributors to the PM2.5 nonattainment problem by the USEPA. The NCDAQ 

agrees with the USEPA that both VOC and ammonia are insignificant contributors to the PM2.5

nonattainment problem in North Carolina. Since these precursors have been deemed 

insignificant, no MVEBs are being established for VOC or ammonia. 

An affirmative insignificance finding from the USEPA only relieves the transportation partners 

from a regional emissions analysis for PM2.5 emissions for these areas and does not relieve them 
On-road Mobile Source Emission Inventory Documentation 28 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

of the other transportation conformity requirements. The transportation partners will need to 

note the PM2.5 insignificance finding (if found adequate and approved by the USEPA) in future 

conformity determinations. 

Reentrained Road Dust

The majority of the roads in North Carolina are paved so there is minimum road dust due to the 

paved roads. The factor to calculate reentrained road dust on paved roads is very small. What 

dust is generated, has been shown in the literature, Methodology to Estimate the Transportable 

Fraction (TF) of Fugitive Dust Emissions for Regional and Urban Scale Air Quality Analyses, 

US EPA, August 3, 2005, to be inconsequential. 

This fact is affirmed by the small crustal component in the PM2.5 speciated data which measures 

only 3% at Hickory monitoring site (Catawba County) in 2002 and only 2% at Lexington 

monitoring site (Davidson County) in 2004 (see Figure 4.5.2-1 below). 

Since the reentrained road dust is not a significant contributor to the PM2.5 nonattainment 

problem, the NCDAQ will not be establishing MVEBs for this source category. An affirmative 

insignificance finding from the USEPA only relieves the transportation partners from a regional 

emissions analysis for reentrained road dust emissions for these areas and does not relieve them 

of the other transportation conformity requirements. The transportation partners will need to 

note the reentrained road dust insignificance finding (if found adequate and approved by the 

USEPA) in future conformity determinations. 

Hickory

AIRS Code 370350004 POC 5 (ROUTINE)

Date(s): 1/2/2002 - 12/4/2002

Average Concentration (μg/m3)

Nitrate

6%

Sulfate

30%

Ammonium

10%

Organic carbon

32%

Elemental carbon

4%

Crustal component

3%

Other

15%

(NC) - Lexington

AIRS Code 370570002 POC 5 (ROUTINE)

Date(s): 1/16/2004 - 2/9/2005

Average Concentration (μg/m3)

Nitrate

7%

Sulfate

29%

Ammonium

10%

Organic carbon

28%

Elemental carbon

4%

Crustal component

2%

Other

20%

Figure 4.5.2-1. Speciated Data for the Hickory area (left) and the Triad area (right) 
On-road Mobile Source Emission Inventory Documentation 29 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Precursor Pollutant SO2

The PM2.5 precursor SO2 could not be deemed insignificant to the PM2.5 nonattainment problem. 

However, the NCDAQ has determined that SO2 emitted by the mobile source sector is 

insignificant. The USEPA in its Federal Register (FR) notice for PM2.5 does not address the 

mobile sector in its listing of significant emissions. North Carolina agrees with the following 

statements addressing SO2 from on-road mobile emissions as published in the May 6, 2005 

Federal Register, (70 FR 24283): 

“While speciated air quality data show that sulfate is a relatively significant component 

(e.g., ranging from nine to 40 percent) of PM2.5 mass in all regions of the country, 

emissions inventory data and projections show that on-road emissions of SOx constitute a 

‘‘de minimis’’ (i.e., extremely small) portion of total SOx emissions. Emissions inventory 

data for 1999 for the 372 potential PM2.5 nonattainment counties for PM2.5 (based on 

1999–2001 air quality data) show that on-road sources were responsible for only two 

percent of total SOx emissions. 

Furthermore, EPA has already adopted two regulations that will greatly reduce 

emissions of SOx from on-road sources by the time such regulations are both in full effect 

in 2009. First, in 2004 the low sulfur gasoline program began to be phased in and will be 

fully effective in 2007 (February 10, 2000, 65 FR 6697). This regulation will reduce the 

sulfur content of gasoline by approximately 90 percent when fully effective. Second, in 

2006 the low sulfur diesel program will begin to be phased in and will be fully effective 

by 2009 (January 18, 2001, 66 FR 5001). This regulation will reduce the sulfur content of 

diesel fuel by approximately 97 percent nationally when fully effective. 

Projections of on-road emissions of SO2 in 2020 indicate that on-road sources will be 

responsible for less than one percent of the total SO2 emissions in 2020 in the 372 

potential PM2.5 nonattainment counties (based on 1999– 2001 air quality data). These 

projections confirm that the implementation of the fuel regulations discussed above will 

ensure that as a general matter of SO2 emissions from on-road sources remain at 

insignificant levels in all areas.” 

Although sulfate is a significant component to the PM2.5 nonattainment problem in North 

Carolina, the majority of the SO2 emissions (which can be oxidized to form SO4) in 2009 come 

from the stationary point source sector (see Figure 4.5.2-2). The mobile source sector only 

contributes one half of one percent (0.5 %) of the 2009 statewide SO2 emissions. This is 

consistent with what the USEPA stated above. 
On-road Mobile Source Emission Inventory Documentation 30 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Since the mobile source SO2 contribution is insignificant, the NCDAQ is not establishing 

MVEBs for this precursor. An affirmative insignificance finding from the USEPA only relieves 

the transportation partners from a regional emissions analysis for SO2 emissions for these areas 

and does not relieve them of the other transportation conformity requirements. The 

transportation partners will need to note the SO2 insignificance finding (if found adequate and 

approved by the USEPA) in future conformity determinations. 

Direct PM2.5 Emissions

The NCDAQ believes strongly that the primary PM2.5 emissions from mobile sources do not 

contribute significantly to the PM2.5 nonattainment problem. However, the USEPA has indicated 

they will not approve a SIP that does not set MVEBs for primary PM2.5 for the Triad. Therefore, 

the NCDAQ will establish county level MVEBs for primary PM2.5 for the Triad. The sections 

that follow discuss the insignificance of PM2.5 emissions for the Hickory area. 

40 CFR 93.109(k) in the Transportation Conformity Rule Amendments for the new 8-hour ozone 

and fine particulate matter National Ambient Air Quality Standards (NAAQSs) addresses areas 

with insignificant motor vehicle emissions as follows, 

“Notwithstanding the other paragraphs in this section, an area is not required to s0atisfy 

a regional emissions analysis for §93.118 and/or §93.119 for a given pollutant/precursor 

and NAAQS, if EPA finds through the adequacy or approval process that a SIP 

demonstrates that regional motor vehicle emissions are an insignificant contributor to 

the air quality problem for that pollutant/precursor and NAAQS. The SIP would have to 

demonstrate that it would be unreasonable to expect that such an area would experience 

Figure 4.5.2-2. North Carolina’s 2009 Statewide SO2 Emissions 

Nonroad

0.6%

Area

2.1%

Mobile

0.5%

Point

96.7%
On-road Mobile Source Emission Inventory Documentation 31 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

enough motor vehicle emissions growth in that pollutant/precursor for a NAAQS 

violation to occur.” 

The rule suggests that such a finding would be based on a number of factors, including the 

percentage of motor vehicle emissions in the context of the total SIP inventory, the current state 

of air quality as determined by monitoring data for that NAAQS, the absence of SIP motor 

vehicle control measures, and historical trends and future projections of the growth of motor 

vehicle emissions. Although there is an inspection and maintenance program in the 

nonattainment areas, this control measure does not control primary PM2.5, but rather is in place to 

reduce the ozone precursors. 

The attainment modeling for the Hickory (Catawba County) and the Triad (Davidson and 

Guilford Counties) PM2.5 nonattainment areas was performed in conjunction with the regional 

haze modeling being done by the Southeast Regional Planning Organization, Visibility 

Improvement State and Tribal Association of the Southeast (VISTAS) and the fine particulate 

matter and ozone modeling being done by the Association of Southeastern Integrated Planning 

(ASIP). VISTAS and ASIP were run by the ten southeast states (Alabama, Florida, Georgia, 

Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and West Virginia). 

In conjunction with that modeling the NCDAQ examined the sources of PM2.5 emissions and 

their contribution to PM2.5 formation in the nonattainment counties. This was accomplished 

using the 2009 emissions inventories developed for the VISTAS/ASIP modeling. Figure 4.5.2-3 

provides the percent contributions from point, area, nonroad mobile and on-road mobile source 

sectors for the Hickory nonattainment area. 

1.59%

68.70%

1.49%

28.22%

Mobile

Point

Area

Nonroad

Figure 4.5.2-3. Hickory Area 2009 Primary PM2.5 Emissions 
On-road Mobile Source Emission Inventory Documentation 32 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

The 2009 on-road mobile PM2.5 emissions contributed only 1.6% of the total PM2.5 emissions for 

the Hickory area. Therefore, it is demonstrated, that the PM2.5 emissions compared to the total 

PM2.5 emissions are insignificant. It should be noted that the mobile source PM2.5 emissions 

slightly decrease from 2002 to 2009 despite an increase in VMT. The Hickory PM2.5 emissions 

go from 100 tons/year in 2002 to 75 tons/year in 2009. Meanwhile, there is an increase in VMT 

in the Hickory area from 4,444,280 miles/day in 2002 to 5,081,590 miles/day in 2009. Further 

justification for the case insignificance of direct PM2.5 emission follows. 

The NCDAQ performed sensitivity modeling using 2008 emissions modeling in order to address 

the challenge of Section 93.109(k) in the Transportation Conformity Rule Amendments, “The 

SIP would have to demonstrate that it would be unreasonable to expect enough motor vehicle 

emissions growth in that pollutant/precursor for a NAAQS violation to occur”. The modeling 

system used was the same as the VISTAS/ASIP modeling and consisted of three components: 

1) the Penn State University/National Center for Atmospheric Research Mesoscale Model (MM5 

version 3.6.1+), 2) the Sparse Matrix Operator Kernel Emissions Modeling System (SMOKE 

version 2.1), and 3) the Community Multiscale Air Quality (CMAQ version 4.4) model. Model 

configurations, input data, and modeling methods are consistent with those suggested by the 

USEPA in Guidance on the Use of Models and Other Analyses in Attainment Demonstrations for 

the 8-hour Ozone NAAQS. 

The primary PM2.5 emissions from on-road mobile sources were doubled in Catawba, Davidson 

and Guilford Counties, therefore, simulating a doubling of the VMT during a 7-day summer time 

simulation. The results of the emissions sensitivities showed such similar results that looking at 

just the difference between two air quality model simulations, one with base case emissions and 

another with increased emissions inputs, showed no change. To show what the differences were 

between the two runs, line graphs of the hourly emissions for the time period modeled for 

Catawba County is displayed in Figures 4.5.2-3. The sensitivity modeling design value (DV) 

increased by 0.04 μg/m3

 in Catawba County. The difference is barely visible as seen in the 

figure below. 
On-road Mobile Source Emission Inventory Documentation 33 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Based on the information discussed above, the NCDAQ believes that the on-road mobile PM2.5

emissions are insignificant contributors to the PM2.5 nonattainment problem in Catawba County. 

Emission estimates indicate that the on-road mobile PM2.5 emissions are a small percentage of 

the total PM2.5 emissions in the Hickory nonattainment area. On-road mobile PM2.5 emissions 

are projected to decrease into the future notwithstanding VMT increases. Air quality modeling 

sensitivities show that doubling the mobile source PM2.5 emissions has very little effect on the 

future design values. The NCDAQ considers it unreasonable to expect that the Hickory PM2.5

nonattainment area will experience enough motor vehicle PM2.5 emissions growth for a future 

PM2.5 violation to occur due to mobile sources. 

Due to above analysis and agreement from the USEPA, budgets for direct PM2.5 will not be set 

for the Hickory nonattainment area. An affirmative insignificance finding from the USEPA only 

relieves the transportation partners from a regional emissions analysis for PM2.5 emissions for 

this area and does not relieve them of the other transportation conformity requirements. The 

transportation partners will need to note the PM2.5 insignificance finding (if found adequate and 

approved by the USEPA) in future conformity determinations. 

4.5.3 Safety Margin 

A safety margin is the difference between the attainment level of emissions from all source 

categories (i.e., point, area, and mobile) and the projected level of emissions from all source 

Figure 4.5.2-4. Catawba County Hourly PM2.5 Emissions 

Cataw ba County Hourly PM2.5

2008 baseline (blue) vs. 2008 w ith 100% On-road Mobile PM2.5 primary increase (red)

0

1

2

3

4

5

6

7

8

9

1 0

1 1

1 2

1 3

1 4

1 5

1 6

1 7

1 8

1 9

2 0

2 1

2 2

2 3

2 4

2 5

2 6

2 7

2 8

2 9

17

1 3192531374349556167737 9859197

1031 09115121127133139145151157163

h our

u g/m3

2008 100% mb PM2.5 increase

2008-baseline
On-road Mobile Source Emission Inventory Documentation 34 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

categories. The State may choose to allocate some of the safety margin to the MVEBs, for 

transportation conformity purposes, so long as the total level of emissions from all source 

categories remains below the attainment level of emissions. In this maintenance plan, the safety 

margin is the difference between the attainment level of emissions (2008) from all man-made 

sources and the projected level of emissions from all man-made sources in the nonattainment 

area. The safety margin for each projected year is listed below in Table 4.5.3-1 and 4.5.3-2. 

Table 4.5.3-1 Safety Margin for Hickory PM2.5 Nonattainment Area 

Year

NOx PM2.5

(tons/year) (kilograms per year) (tons/year) (kilograms per year) 

2011 -4,037 -3,662,304 -67 -60,781 

2014 -5,073 -4,602,148 -126 -114,305 

2017 -5,917 -5,367,811 -180 -163,293 

2021 -6,618 -6,003,748 -253 -229,518 

Table 4.5.3-2 Safety Margin for Triad PM2.5 Nonattainment Area 

Year

NOx PM2.5

(tons/year) (kilograms per year) (tons/year) (kilograms per year) 

2011 -5,247 -4,759,998 -277 -251,290 

2014 -9,150 -8,300,739 -490 -444,520 

2017 -12,270 -11,131,155 -682 -618,700 

2021 -14,759 -13,389,138 -919 -833,703 

There are significant safety margins for both nonattainment areas for 2011 and 2021. The 

NCDAQ has decided to allocate a portion of the safety margin to the MVEBs to allow for 

unanticipated growth in VMT, changes to vehicle mix assumptions, etc. that will influence the 

emission estimations. However, since NOx is a precursor to ozone, we need to limit how much 

safety margin is added to the MVEBs. In 2008 the USEPA lowered the National Ambient Air 

Quality Standard for ozone to 0.075 ppm. The NCDAQ believes adding an additional 10% to 

the 2011 NOx emissions is appropriate for the 2011 NOx MVEBs and adding an additional 20% 

to the 2021 NOx emissions is appropriate for the 2021 NOx MVEBs to account for potential 

changes in VMT, vehicle mix and vehicle age distribution for Catawba, Davidson, and Guilford 

Counties. The NCDAQ believes that setting the 2011 and 2021 PM2.5 MVEBs to the level of 
On-road Mobile Source Emission Inventory Documentation 35 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

PM2.5 emissions present in 2008 is a sufficient safety margin for Davidson and Guilford 

Counties. 

4.5.4 Motor Vehicle Emission Budgets 

As part of the consultation process on setting MVEBs, the NCDAQ sent out a request for 

comment on setting the geographic extent of the MVEBs to all of the transportation partners. A 

copy of the letter can be found in Appendix B. In the letter, the NCDAQ expressed its 

preference for setting county level budgets and the reasons why the NCDAQ believed county 

level budgets were appropriate. With respect to the PM2.5 nonattainment areas, the NCDAQ 

received comments from the Greensboro MPO regarding the geographic extent of the MVEBs. 

The Greensboro MPO agreed with the NCDAQ that MVEBs should be set at the county level. A 

copy of the letter received that relates to the PM2.5 nonattainment areas can be found in 

Appendix B. Therefore MVEBs will be set at the county level. 

According to Section 93.118 of the transportation conformity rule, a maintenance plan must 

establish a MVEB for the last year of the maintenance plan (in this case, 2021). Through the 

interagency consultation process, it was decided that an interim MVEB would be set for the year 

2011 for the Hickory and Triad maintenance plan. 

Tables 4.5.3-1 and 4.5.3-2 below display the PM2.5 and NOx emissions, respectively expressed in 

kilograms per year and the corresponding tons per year for the years MVEBs are being 

established. These two tables are for reference purposes only and are not the tables presenting 

the MVEBs. 

Table 4.5.4-1 On-Road Mobile Source PM2.5 Emissions 

County Kilograms/year Tons/year 

2011 2021 2011 2021 

Davidson 109,769 54,431 121 60 

Guilford 299,371 166,015 330 183 

Triad Total 409,140 220,446 451 243 
On-road Mobile Source Emission Inventory Documentation 36 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.5.4-2 On-Road Mobile Source NOx Emissions 

County Kilograms/year Tons/year 

2011 2021 2011 2021 

Catawba 3,633,274 1,863,357 4,005 2,054 

Davidson 3,714,921 1,790,782 4,095 1,974 

Guilford 10,121,459 5,258,042 11,157 5,796 

Triad Total 13,836,380 7,048,824 15,252 7,770 

Although the emissions are usually expressed in terms of tons, the MVEBs will be set in terms of 

kilograms (kg). The NCDAQ will set MVEB, for transportation conformity purposes, as county 

budgets within the Hickory and Triad maintenance areas for 2011 and 2021. Tables 4.6.4-3 

through 4.6.4-5 below list out the MVEBs in kilograms per year, for transportation conformity 

purposes, by county for the years 2011 and 2021. Upon the USEPA’s affirmative adequacy 

finding for these county level sub-area MVEBs, these MVEBs will become the applicable 

MVEBs for each county. 

Table 4.5.4-3 Catawba County MVEB 

 2011 2021 

NOx Emissions (kg/year)

Base Emissions 3,633,274 1,863,357 

Safety Margin Allocated to MVEB 363,327 372,671 

NOx Conformity MVEB 3,996,601 2,236,028 

Table 4.5.4-4 Davidson County MVEB 

 2011 2021 

NOx Emissions (kg/year)

Base Emissions 3,714,921 1,790,782 

Safety Margin Allocated to MVEB 371,492 358,156 

NOx Conformity MVEB 4,086,413 2,148,938 

PM2.5 Emissions (kg/year)

Base Emissions 109,769 54,431 

Safety Margin Allocated to MVEB 43,544 98,882 

PM2.5 Conformity MVEB 153,313 153,313 
On-road Mobile Source Emission Inventory Documentation 37 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4.5.4-5 Guilford County MVEB 

 2011 2021 

NOx Emissions (kg/year)

Base Emissions 10,121,459 5,258,042 

Safety Margin Allocated to MVEB 1,012,146 1,051,608 

NOx Conformity MVEB 11,133,605 6,309,650 

PM2.5 Emissions (kg/year)

Base Emissions 299,371 166,015 

Safety Margin Allocated to MVEB 122,470 255,826 

PM2.5 Conformity MVEB 421,841 421,841 

Tables 4.5.4-6 and 4.5.4-7 list that portion of the safety margin that was added to the mobile 

source emissions to develop the MVEBs. These values can be compared to those in Tables 

4.5.4-1 and 4.5.4-2 to see that NCDAQ added only a small fraction of that which was available. 

With these safety margins, it is projected that emissions from all source categories will remain 

below the attainment level emissions. 

Table 4.5.4-6 County Level PM2.5 MVEB Safety Margin for 2011 and 2021 

County 

2011 MVEB Safety 

Margin 

(Kilograms/year) 

2021 MVEB Safety 

Margin 

(Kilograms/year) 

Triad Total 166,014 354,708 

Table 4.5.4-7 County Level NOx MVEB Safety Margin for 2011 and 2021 

County 

2011 MVEB Safety 

Margin 

(Kilograms/year) 

2021 MVEB Safety 

Margin 

(Kilograms/year) 

Catawba 363,327 372,671 

Triad Total 1,383,638 1,409,764 

For the Hickory nonattainment area, a total of 363,327 kg/year (400 tons/year) and 372,671 

kg/year (411 tons/year) of the 2011 and 2021 NOx safety margins, respectively, were added to 

the NOX MVEBs. 
On-road Mobile Source Emission Inventory Documentation 38 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

For the Triad nonattainment area, a total of 1,383,638 kg/year (1,525 tons/year) and 1,409,764 

kg/year 1,554 tons/year) of the 2011 and 2021 NOx safety margins, respectively, were added to 

the Triad NOX MVEBs. For PM2.5, a total of 166,014 kg/year (183 tons/year) and 354,708 

kg/year (391 tons/year) of the 2011 and 2021 PM2.5 safety margins, respectively, were added to 

the Triad PM2.5 MVEBs. Tables 4.5.4-8 and 4.5.4-9 reflect the remaining safety margins. 

Table 4.5.4-8 New Safety Margins for the Hickory PM2.5 nonattainment area 

Year NOx TPY PM2.5 TPY 

2011 -3,637 -67 

2014 -5,073 -126 

2017 -5,917 -180 

2021 -6,207 -253 

Table 4.5.4-9 New Safety Margins for the Triad PM2.5 nonattainment area 

Year NOx TPY PM2.5 TPY 

2011 -3,722 -94 

2014 -9,150 -490 

2017 -12,270 -682 

2021 -13,205 -528 
On-road Mobile Source Emission Inventory Documentation 39 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.0 DATA USED 

5.1 North Carolina’s Vehicle Mix 

5.1.1 2008 State Vehicle Mix 

Rural 2008 State Vehicle Mix 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.3219 0.0715 0.2381 0.0734 0.0337 0.0814 0.0080 0.0065 

0.0050 0.0183 0.0214 0.0233 0.0833 0.0072 0.0032 0.0038 

Princ. Art. 

0.3731 0.0829 0.2761 0.0851 0.0391 0.0423 0.0041 0.0034 

0.0026 0.0095 0.0111 0.0121 0.0433 0.0054 0.0024 0.0075 

Minor Art. 

0.3796 0.0843 0.2808 0.0865 0.0398 0.0376 0.0037 0.0030 

0.0023 0.0084 0.0099 0.0108 0.0385 0.0062 0.0028 0.0058 

Major Collector 

0.4002 0.0889 0.2960 0.0912 0.0419 0.0232 0.0023 0.0019 

0.0014 0.0052 0.0061 0.0066 0.0237 0.0037 0.0017 0.0060 

Minor Collector 

0.3969 0.0882 0.2937 0.0905 0.0416 0.0247 0.0024 0.0020 

0.0015 0.0055 0.0065 0.0071 0.0253 0.0048 0.0021 0.0072 

Local 

0.3829 0.0851 0.2832 0.0873 0.0401 0.0300 0.0029 0.0024 

0.0019 0.0067 0.0079 0.0086 0.0307 0.0131 0.0059 0.0113 

Urban 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.3510 0.0780 0.2596 0.0800 0.0368 0.0594 0.0058 0.0047 

0.0037 0.0133 0.0156 0.0170 0.0608 0.0061 0.0028 0.0054 

Freeway 

0.3805 0.0845 0.2815 0.0867 0.0399 0.0384 0.0038 0.0031 

0.0024 0.0086 0.0101 0.0110 0.0393 0.0047 0.0021 0.0034 

Princ. Art. 

0.3987 0.0886 0.2950 0.0909 0.0418 0.0244 0.0024 0.0020 

0.0015 0.0055 0.0064 0.0070 0.0250 0.0036 0.0016 0.0056 

Minor Art 

0.4095 0.0910 0.3029 0.0933 0.0429 0.0161 0.0016 0.0013 

0.0010 0.0036 0.0042 0.0046 0.0165 0.0037 0.0017 0.0061 

Coll 

0.4117 0.0915 0.3047 0.0939 0.0432 0.0140 0.0014 0.0011 

0.0009 0.0031 0.0037 0.0040 0.0143 0.0033 0.0015 0.0077 

Local 

0.3957 0.0880 0.2929 0.0902 0.0415 0.0192 0.0019 0.0015 

0.0012 0.0043 0.0050 0.0055 0.0196 0.0159 0.0072 0.0104 
On-road Mobile Source Emission Inventory Documentation 40 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.1.2 2011 State Vehicle Mix 

Rural 2011 State Vehicle Mix 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2894 0.0770 0.2561 0.0789 0.0363 0.0828 0.0081 0.0068 

0.0051 0.0185 0.0219 0.0238 0.0845 0.0042 0.0021 0.0045 

Princ. Art. 

0.3367 0.0896 0.2980 0.0918 0.0423 0.0438 0.0043 0.0036 

0.0027 0.0098 0.0116 0.0126 0.0447 0.0022 0.0011 0.0052 

Minor Art. 

0.3421 0.0909 0.3024 0.0932 0.0429 0.0396 0.0039 0.0032 

0.0024 0.0088 0.0105 0.0114 0.0404 0.0020 0.0010 0.0053 

Major Collector 

0.3606 0.0958 0.3188 0.0982 0.0452 0.0244 0.0024 0.0020 

0.0015 0.0054 0.0064 0.0070 0.0249 0.0012 0.0006 0.0056 

Minor Collector 

0.3581 0.0952 0.3167 0.0976 0.0449 0.0263 0.0026 0.0022 

0.0016 0.0059 0.0069 0.0076 0.0269 0.0013 0.0007 0.0055 

Local 

0.3471 0.0923 0.3070 0.0946 0.0435 0.0354 0.0034 0.0029 

0.0022 0.0079 0.0093 0.0102 0.0361 0.0018 0.0009 0.0054 

Urban 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.3161 0.0841 0.2797 0.0862 0.0397 0.0608 0.0059 0.0050 

0.0037 0.0136 0.0161 0.0175 0.0620 0.0031 0.0016 0.0049 

Freeway 

0.3418 0.0909 0.3023 0.0932 0.0429 0.0397 0.0039 0.0033 

0.0024 0.0089 0.0105 0.0114 0.0405 0.0020 0.0010 0.0053 

Princ. Art. 

0.3590 0.0954 0.3176 0.0979 0.0451 0.0255 0.0025 0.0021 

0.0016 0.0057 0.0067 0.0073 0.0260 0.0013 0.0007 0.0056 

Minor Art 

0.3691 0.0980 0.3262 0.1005 0.0463 0.0174 0.0017 0.0014 

0.0011 0.0039 0.0046 0.0050 0.0178 0.0009 0.0004 0.0057 

Coll 

0.3717 0.0988 0.3286 0.1013 0.0466 0.0152 0.0015 0.0012 

0.0009 0.0034 0.0040 0.0044 0.0155 0.0008 0.0004 0.0057 

Local 

0.3585 0.0952 0.3169 0.0977 0.0450 0.0261 0.0025 0.0021 

0.0016 0.0058 0.0069 0.0075 0.0267 0.0013 0.0007 0.0055 
On-road Mobile Source Emission Inventory Documentation 41 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.1.3 2014 State Vehicle Mix 

Rural 2014 State Vehicle Mix 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2658 0.0811 0.2698 0.0831 0.0382 0.0827 0.0080 0.0068 

0.0051 0.0186 0.0218 0.0237 0.0846 0.0042 0.0021 0.0044 

Princ. Art. 

0.3095 0.0943 0.3139 0.0967 0.0445 0.0437 0.0042 0.0036 

0.0027 0.0098 0.0115 0.0125 0.0447 0.0022 0.0011 0.0051 

Minor Art. 

0.3143 0.0957 0.3186 0.0981 0.0451 0.0395 0.0038 0.0032 

0.0024 0.0089 0.0104 0.0113 0.0405 0.0020 0.0010 0.0052 

Major Collector 

0.3310 0.1009 0.3358 0.1034 0.0476 0.0243 0.0024 0.0020 

0.0015 0.0055 0.0064 0.0070 0.0249 0.0012 0.0006 0.0055 

Minor Collector 

0.3287 0.1003 0.3336 0.1028 0.0473 0.0263 0.0026 0.0022 

0.0016 0.0059 0.0069 0.0075 0.0269 0.0013 0.0007 0.0054 

Local 

0.3186 0.0972 0.3234 0.0996 0.0458 0.0353 0.0034 0.0029 

0.0022 0.0080 0.0093 0.0101 0.0362 0.0018 0.0009 0.0053 

Urban 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2904 0.0885 0.2946 0.0908 0.0417 0.0607 0.0059 0.0050 

0.0037 0.0137 0.0160 0.0174 0.0621 0.0031 0.0016 0.0048 

Freeway 

0.3140 0.0957 0.3185 0.0981 0.0451 0.0396 0.0039 0.0032 

0.0024 0.0089 0.0104 0.0114 0.0406 0.0020 0.0010 0.0052 

Princ. Art. 

0.3296 0.1005 0.3345 0.1030 0.0474 0.0255 0.0025 0.0021 

0.0016 0.0057 0.0067 0.0073 0.0261 0.0013 0.0007 0.0055 

Minor Art 

0.3387 0.1033 0.3436 0.1059 0.0487 0.0174 0.0017 0.0014 

0.0011 0.0039 0.0046 0.0050 0.0178 0.0009 0.0004 0.0056 

Coll 

0.3414 0.1040 0.3462 0.1066 0.0490 0.0152 0.0015 0.0012 

0.0009 0.0034 0.0040 0.0043 0.0155 0.0008 0.0004 0.0056 

Local 

0.3291 0.1003 0.3338 0.1028 0.0473 0.0261 0.0025 0.0021 

0.0016 0.0059 0.0069 0.0075 0.0267 0.0013 0.0007 0.0054 
On-road Mobile Source Emission Inventory Documentation 42 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.1.4 2017 State Vehicle Mix 

Rural 2017 State Vehicle Mix 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2490 0.0839 0.2795 0.0861 0.0396 0.0825 0.0082 0.0069 

0.0051 0.0185 0.0219 0.0238 0.0844 0.0042 0.0021 0.0043 

Princ. Art. 

0.2897 0.0976 0.3252 0.1002 0.0461 0.0436 0.0043 0.0037 

0.0027 0.0098 0.0116 0.0126 0.0446 0.0022 0.0011 0.0050 

Minor Art. 

0.2939 0.0991 0.3301 0.1017 0.0468 0.0395 0.0039 0.0033 

0.0024 0.0089 0.0105 0.0114 0.0404 0.0020 0.0010 0.0051 

Major Collector 

0.3101 0.1045 0.3479 0.1072 0.0493 0.0243 0.0024 0.0020 

0.0015 0.0054 0.0064 0.0070 0.0248 0.0012 0.0006 0.0054 

Minor Collector 

0.3079 0.1038 0.3456 0.1065 0.0490 0.0262 0.0026 0.0022 

0.0016 0.0059 0.0070 0.0076 0.0268 0.0013 0.0007 0.0053 

Local 

0.2982 0.1006 0.3350 0.1032 0.0475 0.0353 0.0035 0.0030 

0.0022 0.0079 0.0094 0.0102 0.0361 0.0018 0.0009 0.0052 

Urban 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2721 0.0916 0.3052 0.0940 0.0432 0.0606 0.0060 0.0051 

0.0037 0.0136 0.0161 0.0175 0.0620 0.0031 0.0015 0.0047 

Freeway 

0.2940 0.0991 0.3299 0.1017 0.0467 0.0396 0.0039 0.0033 

0.0024 0.0089 0.0105 0.0114 0.0405 0.0020 0.0010 0.0051 

Princ. Art. 

0.3091 0.1040 0.3465 0.1068 0.0491 0.0254 0.0025 0.0021 

0.0016 0.0057 0.0067 0.0073 0.0260 0.0013 0.0006 0.0053 

Minor Art 

0.3172 0.1069 0.3560 0.1097 0.0504 0.0174 0.0017 0.0015 

0.0011 0.0039 0.0046 0.0050 0.0178 0.0009 0.0004 0.0055 

Coll 

0.3196 0.1077 0.3586 0.1105 0.0508 0.0151 0.0015 0.0013 

0.0009 0.0034 0.0040 0.0044 0.0155 0.0008 0.0004 0.0055 

Local 

0.3083 0.1038 0.3458 0.1066 0.0490 0.0260 0.0026 0.0022 

0.0016 0.0058 0.0069 0.0075 0.0266 0.0013 0.0007 0.0053 
On-road Mobile Source Emission Inventory Documentation 43 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.1.5 2021 State Vehicle Mix 

Rural 2020+ State Vehicle Mix 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2366 0.0861 0.2865 0.0883 0.0406 0.0825 0.0081 0.0069 

0.0052 0.0185 0.0219 0.0238 0.0844 0.0042 0.0021 0.0043 

Princ. Art. 

0.2751 0.1002 0.3334 0.1028 0.0473 0.0436 0.0043 0.0036 

0.0028 0.0098 0.0116 0.0126 0.0446 0.0022 0.0011 0.0050 

Minor Art. 

0.2791 0.1017 0.3384 0.1043 0.0480 0.0395 0.0039 0.0033 

0.0025 0.0089 0.0105 0.0114 0.0404 0.0020 0.0010 0.0051 

Major Collector 

0.2945 0.1072 0.3567 0.1099 0.0506 0.0243 0.0024 0.0020 

0.0015 0.0055 0.0064 0.0070 0.0248 0.0012 0.0006 0.0054 

Minor Collector 

0.2924 0.1065 0.3543 0.1092 0.0503 0.0262 0.0026 0.0022 

0.0017 0.0059 0.0070 0.0076 0.0268 0.0013 0.0007 0.0053 

Local 

0.2833 0.1032 0.3435 0.1059 0.0487 0.0353 0.0035 0.0029 

0.0022 0.0079 0.0094 0.0102 0.0361 0.0018 0.0009 0.0052 

Urban 

LDV LDT1 LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 

HDV5 HDV6 HDV7 HDV8a HDV8b HDBS HDBT MC 

Interstate 

0.2583 0.0940 0.3129 0.0964 0.0444 0.0606 0.0060 0.0051 

0.0038 0.0136 0.0161 0.0175 0.0620 0.0031 0.0015 0.0047 

Freeway 

0.2790 0.1017 0.3383 0.1043 0.0480 0.0396 0.0039 0.0033 

0.0025 0.0089 0.0105 0.0114 0.0405 0.0020 0.0010 0.0051 

Princ. Art. 

0.2934 0.1068 0.3553 0.1095 0.0504 0.0254 0.0025 0.0021 

0.0016 0.0057 0.0067 0.0073 0.0260 0.0013 0.0006 0.0054 

Minor Art 

0.3013 0.1097 0.3650 0.1125 0.0518 0.0174 0.0017 0.0014 

0.0011 0.0039 0.0046 0.0050 0.0178 0.0009 0.0004 0.0055 

Coll 

0.3033 0.1105 0.3677 0.1133 0.0522 0.0152 0.0015 0.0013 

0.0010 0.0034 0.0040 0.0044 0.0155 0.0008 0.0004 0.0055 

Local 

0.2926 0.1066 0.3546 0.1093 0.0503 0.0260 0.0026 0.0022 

0.0016 0.0059 0.0069 0.0075 0.0266 0.0013 0.0007 0.0053 
On-road Mobile Source Emission Inventory Documentation 44 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

5.2 Meteorology 

5.2.1 Catawba County Temperature and Relative Humidity 

STATE CLIMATE OFFICE OF NORTH CAROLINA 

NC CRONOS Database 

2008 data retrieval from Hickory Airport (KHKY) 

Hickory, Burke County 

Latitude: 35.7411464 Longitude: -81.3895489 

Elevation: 1189 ft. 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

1 0 31 35.9 67 

1 1 31 34.5 71 

1 2 31 34.2 72 

1 3 31 33.7 74 

1 4 31 33 76 

1 5 31 32.5 75 

1 6 31 32.3 75 

1 7 31 32.3 75 

1 8 31 34.7 70 

1 9 31 37.6 63 

1 10 31 40.7 54 

1 11 31 42.9 50 

1 12 31 44.9 46 

1 13 31 46.3 45 

1 14 31 46.9 44 

1 15 31 46.5 45 

1 16 31 45.4 46 

1 17 31 42.8 51 

1 18 31 40.9 56 

1 19 31 40 58 

1 20 30 38.8 62 

1 21 31 37.9 62 

1 22 31 37.1 65 

1 23 31 36.6 67 

2 0 29 40.1 72 

2 1 29 39.5 73 

2 2 29 38.7 75 

2 3 29 38.1 75 

2 4 29 37 78 

2 5 29 36.7 79 

2 6 29 36.5 79 

2 7 29 36.8 78 

2 8 29 39.4 74 

2 9 29 42.8 68 

2 10 29 45.8 62 

2 11 29 48.5 58 
On-road Mobile Source Emission Inventory Documentation 45 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

2 12 29 50.7 55 

2 13 29 52 53 

2 14 29 52.5 52 

2 15 29 53.1 50 

2 16 29 52.3 51 

2 17 29 49.8 55 

2 18 29 47.5 57 

2 19 29 45.6 61 

2 20 29 44.7 62 

2 21 29 43.6 64 

2 22 29 42.4 66 

2 23 29 41.4 68 

3 0 31 46.7 63 

3 1 31 45.5 65 

3 2 31 44.1 68 

3 3 31 43.9 68 

3 4 31 42.9 70 

3 5 31 41.9 73 

3 6 31 41.9 74 

3 7 31 44.2 72 

3 8 31 47.7 63 

3 9 31 51.4 56 

3 10 31 54.1 50 

3 11 31 56.2 48 

3 12 31 57.1 49 

3 13 31 58.2 48 

3 14 31 58.5 46 

3 15 31 58.7 46 

3 16 31 58.4 46 

3 17 31 57.2 48 

3 18 31 54.8 52 

3 19 31 52.7 55 

3 20 31 51.6 57 

3 21 31 50.4 58 

3 22 31 49.2 61 

3 23 31 47.6 64 

4 0 30 53.6 76 

4 1 30 53.2 78 

4 2 30 51.9 80 

4 3 30 51.3 80 

4 4 30 50.6 82 

4 5 30 50 82 

4 6 30 51.4 81 

4 7 30 53.9 76 

4 8 30 56.8 69 

4 9 30 59.8 63 

4 10 30 61.4 61 

4 11 30 63.3 57 

4 12 30 64.3 54 
On-road Mobile Source Emission Inventory Documentation 46 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

4 13 30 65.6 54 

4 14 29 66.8 52 

4 15 30 66.1 52 

4 16 30 65.7 51 

4 17 30 64 55 

4 18 30 62 58 

4 19 30 59.7 63 

4 20 30 58.3 65 

4 21 30 56.9 68 

4 22 30 55.7 71 

4 23 30 54.6 73 

5 0 31 60.6 73 

5 1 31 59.5 76 

5 2 31 58.7 78 

5 3 31 58.2 78 

5 4 31 57.1 81 

5 5 31 56.7 84 

5 6 31 59.1 80 

5 7 30 61.7 73 

5 8 31 65.9 64 

5 9 31 68.6 59 

5 10 31 70.8 55 

5 11 31 73.3 50 

5 12 31 75.1 47 

5 13 31 75.4 45 

5 14 31 75.4 45 

5 15 31 75.3 46 

5 16 31 74.5 46 

5 17 31 73.2 49 

5 18 31 70.7 52 

5 19 31 68 56 

5 20 31 66.1 61 

5 21 31 64.3 65 

5 22 31 63.6 66 

5 23 31 62.4 71 

6 0 30 70.3 76 

6 1 30 69.3 78 

6 2 30 67.7 81 

6 3 30 66.9 82 

6 4 30 66.4 83 

6 5 30 66.5 84 

6 6 30 69.5 78 

6 7 30 73.9 69 

6 8 30 78.6 58 

6 9 30 82.4 49 

6 10 30 84.9 44 

6 11 30 86.4 40 

6 12 30 87.9 37 

6 13 30 89 35 
On-road Mobile Source Emission Inventory Documentation 47 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

6 14 30 88.6 36 

6 15 30 87.1 39 

6 16 30 85.7 43 

6 17 30 83.5 47 

6 18 30 81.3 51 

6 19 30 77.8 57 

6 20 30 75.9 61 

6 21 30 74.3 65 

6 22 30 73 68 

6 23 30 71.4 73 

7 0 31 70.7 84 

7 1 31 69.3 87 

7 2 31 68.9 87 

7 3 31 68 90 

7 4 31 67.5 90 

7 5 31 67.4 90 

7 6 31 69 87 

7 7 31 71.9 80 

7 8 31 75.8 71 

7 9 31 78.7 64 

7 10 31 81.5 58 

7 11 31 83.1 54 

7 12 31 84.6 51 

7 13 31 83.9 52 

7 14 31 83.6 54 

7 15 31 82.7 56 

7 16 31 83.5 54 

7 17 31 82.3 57 

7 18 31 79.8 62 

7 19 31 76.8 68 

7 20 31 75.4 72 

7 21 31 73.8 76 

7 22 31 72.7 80 

7 23 31 71.7 82 

8 0 31 70.4 84 

8 1 31 69.3 86 

8 2 31 68.2 88 

8 3 31 67.5 89 

8 4 31 66.9 90 

8 5 31 66.4 91 

8 6 31 67.8 89 

8 7 31 70.7 82 

8 8 31 74 73 

8 9 31 77.4 65 

8 10 31 79.2 59 

8 11 31 80.8 56 

8 12 31 82.1 55 

8 13 31 82.7 54 

8 14 31 82.9 54 
On-road Mobile Source Emission Inventory Documentation 48 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

8 15 31 82.6 55 

8 16 31 82 55 

8 17 31 80.8 57 

8 18 31 78.6 62 

8 19 31 76.2 67 

8 20 31 74.8 71 

8 21 31 73.7 74 

8 22 31 72.2 78 

8 23 31 71.1 81 

9 0 30 65.3 89 

9 1 30 64.6 90 

9 2 30 64 92 

9 3 30 63.4 93 

9 4 30 63 93 

9 5 30 62.6 93 

9 6 30 63.3 92 

9 7 30 65.2 89 

9 8 30 68.7 80 

9 9 30 71.9 71 

9 10 30 74.3 64 

9 11 30 75.1 62 

9 12 30 76.5 59 

9 13 30 77.6 58 

9 14 30 77.5 58 

9 15 30 77.1 59 

9 16 30 76.1 62 

9 17 30 73.9 67 

9 18 30 70.7 74 

9 19 30 69.4 78 

9 20 30 68.1 82 

9 21 30 67 84 

9 22 30 66.2 87 

9 23 30 65.3 89 

10 0 31 51.7 84 

10 1 31 51.1 85 

10 2 31 50.8 85 

10 3 31 49.9 86 

10 4 31 49.1 88 

10 5 31 48.8 88 

10 6 31 48.4 88 

10 7 31 51.6 82 

10 8 31 55.7 73 

10 9 31 59.6 64 

10 10 31 62.6 57 

10 11 31 64.8 52 

10 12 31 66.1 50 

10 13 31 66.7 48 

10 14 31 66.7 48 

10 15 31 66.2 49 
On-road Mobile Source Emission Inventory Documentation 49 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

10 16 31 64.4 52 

10 17 31 60.7 59 

10 18 31 58.5 64 

10 19 31 56.7 68 

10 20 31 55.4 73 

10 21 31 53.9 78 

10 22 31 52.7 81 

10 23 31 52 83 

11 0 30 41.9 76 

11 1 30 41.1 78 

11 2 30 40.8 78 

11 3 30 40.6 77 

11 4 30 39.9 78 

11 5 30 39.6 79 

11 6 30 39.6 79 

11 7 30 40.3 79 

11 8 30 44.5 70 

11 9 30 48.1 59 

11 10 30 50.9 53 

11 11 30 53.2 48 

11 12 30 54.6 45 

11 13 30 55.5 43 

11 14 30 55.5 44 

11 15 30 54.8 45 

11 16 30 53.1 48 

11 17 30 49.8 54 

11 18 30 48.2 58 

11 19 30 46.8 61 

11 20 30 46.1 64 

11 21 30 44.8 66 

11 22 30 43.8 69 

11 23 30 42.4 74 

12 0 31 41.2 78 

12 1 31 41 78 

12 2 31 39.8 80 

12 3 31 40 79 

12 4 31 39.7 81 

12 5 31 39.5 80 

12 6 31 39.6 79 

12 7 31 39.2 80 

12 8 31 41.2 76 

12 9 31 43.5 71 

12 10 31 45.5 66 

12 11 31 47.4 62 

12 12 31 48.7 59 

12 13 31 49.9 57 

12 14 31 50.3 56 

12 15 31 50 56 

12 16 31 48.5 59 
On-road Mobile Source Emission Inventory Documentation 50 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

12 17 31 46.5 64 

12 18 31 45.2 66 

12 19 31 44.3 68 

12 20 31 43.3 71 

12 21 31 42.6 72 

12 22 31 42.1 74 

12 23 31 41.6 74 

5.2.2 Davidson and Guilford County Temperature and Relative Humidity 

STATE CLIMATE OFFICE OF NORTH CAROLINA 

NC CRONOS Database 

2008 data retrieval from Greensboro Airport (KGSO) 

Greensboro, Guilford County 

Latitude: 36.0977469 Longitude: -79.9372975 

Elevation: 926 ft. 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

1 0 31 36.2 62 

1 1 31 35.8 63 

1 2 31 35.9 63 

1 3 30 36.5 65 

1 4 31 35.8 65 

1 5 31 35 66 

1 6 31 34.2 66 

1 7 31 34.4 65 

1 8 31 36.6 62 

1 9 31 39.2 55 

1 10 31 41.5 49 

1 11 31 43.6 45 

1 12 31 45.5 42 

1 13 31 46.5 41 

1 14 30 46.9 40 

1 15 30 46.6 41 

1 16 30 45.2 43 

1 17 31 42.9 46 

1 18 31 41.1 50 

1 19 31 39.9 52 

1 20 31 39 54 

1 21 31 38.5 56 

1 22 31 37.7 57 

1 23 31 36.8 60 

2 0 29 40.9 64 

2 1 29 39.7 66 
On-road Mobile Source Emission Inventory Documentation 51 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

2 2 29 39.3 66 

2 3 29 38.7 67 

2 4 29 38.2 68 

2 5 29 37.9 68 

2 6 29 37.5 69 

2 7 29 38.4 69 

2 8 29 40.9 65 

2 9 29 43.5 59 

2 10 29 46.6 55 

2 11 29 49.1 50 

2 12 29 51.2 47 

2 13 29 52.9 45 

2 14 29 53.6 45 

2 15 29 53.2 46 

2 16 29 52.3 47 

2 17 29 50.1 50 

2 18 29 48.5 53 

2 19 29 46.7 55 

2 20 29 45.4 57 

2 21 29 44.1 59 

2 22 29 42.7 62 

2 23 29 42 63 

3 0 31 47.4 61 

3 1 31 46.7 61 

3 2 31 45.4 63 

3 3 31 44.7 65 

3 4 31 44 66 

3 5 31 43.4 66 

3 6 31 43.1 67 

3 7 31 46 62 

3 8 31 48.9 56 

3 9 31 51.6 51 

3 10 31 54.2 47 

3 11 31 56.7 42 

3 12 31 58.1 40 

3 13 31 59 39 

3 14 31 59.3 41 

3 15 31 59.4 41 

3 16 31 58.4 42 

3 17 31 56.9 44 

3 18 31 55.1 46 

3 19 31 53.4 50 

3 20 31 52.3 53 

3 21 31 50.6 56 

3 22 31 49.7 58 

3 23 31 48.6 60 

4 0 30 53.6 76 

4 1 30 53.2 76 

4 2 30 52 78 
On-road Mobile Source Emission Inventory Documentation 52 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

4 3 30 51.5 78 

4 4 30 50.8 78 

4 5 30 50.5 78 

4 6 30 52.1 76 

4 7 30 55 69 

4 8 30 57.7 64 

4 9 30 59.9 60 

4 10 30 61.7 56 

4 11 30 63 53 

4 12 30 64.1 53 

4 13 30 65.2 51 

4 14 30 65.1 51 

4 15 30 64.9 53 

4 16 30 64.7 53 

4 17 30 63.6 54 

4 18 30 61.2 59 

4 19 30 59.4 62 

4 20 30 58.3 64 

4 21 30 57.2 67 

4 22 30 55.9 69 

4 23 30 54.7 72 

5 0 31 60.2 69 

5 1 31 59.6 70 

5 2 31 58.8 73 

5 3 31 58.3 74 

5 4 31 57.8 75 

5 5 31 57.8 75 

5 6 31 60.4 71 

5 7 31 63.4 65 

5 8 31 66.3 59 

5 9 31 68.8 55 

5 10 31 70.6 51 

5 11 31 72.3 48 

5 12 31 73.4 46 

5 13 31 74.3 44 

5 14 31 74.5 45 

5 15 31 74.5 44 

5 16 31 73.6 45 

5 17 31 72.7 46 

5 18 31 70.2 51 

5 19 31 67.6 55 

5 20 31 65.6 59 

5 21 31 64.3 62 

5 22 31 63 64 

5 23 31 61.9 67 

6 0 30 72.4 68 

6 1 30 71.7 69 

6 2 30 70.7 72 

6 3 30 69.5 74 
On-road Mobile Source Emission Inventory Documentation 53 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

6 4 30 68.7 76 

6 5 30 69.7 75 

6 6 30 72.8 69 

6 7 30 76.6 61 

6 8 30 79.8 54 

6 9 30 82.3 48 

6 10 30 85 43 

6 11 30 86.3 40 

6 12 30 87.8 37 

6 13 30 88.4 35 

6 14 30 88.6 35 

6 15 30 87.5 36 

6 16 30 86.4 39 

6 17 30 84.1 43 

6 18 30 81.4 49 

6 19 30 78.9 53 

6 20 30 77.2 57 

6 21 30 76 59 

6 22 30 74.9 61 

6 23 30 73.5 64 

7 0 31 72.1 74 

7 1 31 70.9 78 

7 2 31 70.5 78 

7 3 31 70.1 79 

7 4 31 69.4 81 

7 5 31 69.7 80 

7 6 31 72.1 76 

7 7 31 75 70 

7 8 31 78.1 63 

7 9 31 81 56 

7 10 31 82.7 52 

7 11 31 84.1 48 

7 12 31 85 46 

7 13 31 85.2 46 

7 14 31 86 44 

7 15 31 85.6 45 

7 16 31 84.5 48 

7 17 31 83 51 

7 18 31 80.5 56 

7 19 31 78 61 

7 20 31 76.4 66 

7 21 31 75 69 

7 22 31 74.1 71 

7 23 31 73.2 73 

8 0 31 70.9 74 

8 1 31 70.4 76 

8 2 31 69.5 77 

8 3 31 69 79 

8 4 31 68.5 79 
On-road Mobile Source Emission Inventory Documentation 54 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

8 5 31 67.9 81 

8 6 31 69.9 77 

8 7 31 72.9 71 

8 8 31 75.7 65 

8 9 31 78 59 

8 10 31 80.3 54 

8 11 31 82.1 51 

8 12 31 83 48 

8 13 31 84 47 

8 14 31 83.8 48 

8 15 31 83.1 48 

8 16 31 82.6 48 

8 17 31 81.3 51 

8 18 31 79 55 

8 19 31 76.9 59 

8 20 31 75.3 63 

8 21 31 73.9 67 

8 22 31 73 69 

8 23 31 72 72 

9 0 30 66.5 80 

9 1 30 65.7 82 

9 2 30 65.3 82 

9 3 30 65 83 

9 4 30 64.2 85 

9 5 30 63.9 85 

9 6 30 64.8 83 

9 7 30 66.9 79 

9 8 30 69.8 72 

9 9 30 71.9 68 

9 10 30 73.7 63 

9 11 30 75.3 59 

9 12 30 76.3 57 

9 13 30 76.9 56 

9 14 30 77.1 56 

9 15 30 76.7 57 

9 16 30 76.1 59 

9 17 30 74 64 

9 18 30 71.9 69 

9 19 30 70.3 73 

9 20 30 69 74 

9 21 30 68.4 76 

9 22 30 67.5 78 

9 23 30 66.8 80 

10 0 31 52.9 77 

10 1 31 52 79 

10 2 31 51.1 80 

10 3 31 50.4 81 

10 4 31 50.2 81 

10 5 31 49.4 82 
On-road Mobile Source Emission Inventory Documentation 55 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

10 6 31 49.8 81 

10 7 31 53.6 75 

10 8 31 57.8 64 

10 9 31 60.9 57 

10 10 31 62.9 53 

10 11 31 64.6 50 

10 12 31 65.9 47 

10 13 30 67.1 46 

10 14 31 67.2 44 

10 15 31 66.5 44 

10 16 31 64.6 49 

10 17 31 61.7 54 

10 18 31 59.4 60 

10 19 31 57.4 65 

10 20 31 55.9 69 

10 21 31 55 71 

10 22 31 54 73 

10 23 31 52.9 75 

11 0 30 43 69 

11 1 30 42 72 

11 2 30 41.4 73 

11 3 30 41.2 73 

11 4 30 40.8 73 

11 5 30 40.4 74 

11 6 30 40.2 74 

11 7 30 42 72 

11 8 30 46.5 63 

11 9 30 49.6 56 

11 10 30 51.6 53 

11 11 30 53.3 49 

11 12 30 54.4 47 

11 13 30 55.4 44 

11 14 30 55.3 43 

11 15 30 54.8 44 

11 16 30 52.6 48 

11 17 30 50.5 51 

11 18 30 48.2 56 

11 19 30 47 59 

11 20 30 45.7 62 

11 21 30 44.4 66 

11 22 30 44.1 67 

11 23 30 43.7 68 

12 0 31 43 71 

12 1 31 42.2 72 

12 2 31 42 71 

12 3 31 41.3 72 

12 4 31 41 72 

12 5 31 40.8 72 

12 6 31 40.7 72 
On-road Mobile Source Emission Inventory Documentation 56 

Hickory and Greensboro/Winston-Salem/Highpoint Annual PM2.5 Appendix C.3 

Supplement to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

Month Hour 

Number of Records 

Compiled 

Average 

Temperature (F) 

Average Relative 

Humidity (%) 

12 7 31 40.7 71 

12 8 31 42.9 67 

12 9 31 45.1 63 

12 10 31 47.1 59 

12 11 31 48.7 56 

12 12 31 49.8 53 

12 13 31 50.6 52 

12 14 31 51 52 

12 15 31 50.5 52 

12 16 31 49 55 

12 17 31 47.2 58 

12 18 31 46.1 60 

12 19 31 45.2 63 

12 20 31 44.3 65 

12 21 31 43.4 68 

12 22 31 43.3 67 

12 23 31 42.8 69