## Appendix E

. Development of the Base

- and Future

- Year

Mobile Source Emission s Inventory for the Treasure Valley,

IdahoThis page intentionally left blank for correct double

- sided printing.

## Development of the B ase
- and Future

- Y ear Mobile Source

Emission s Inventory for the Treasure Valley, Idaho

July 2012

Prepared by

Idaho Department of Environmental Quality
Technical Services Division

1410 N. Hilton Boise, Idaho 83706This page intentionally left blank for correct double

- sided printing.Base

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iii 

### Table of Contents

List of Figures

................................ ................................ ................................ ................................ iv

List of Tables

................................ ................................ ................................ ................................ . iv
Abbreviations, Acronyms, and Symbols

................................ ................................ ........................ v

1 Introduction

................................ ................................ ................................ .............................. 1

2 Methodology: MOVES Input Database Development

................................ ............................ 2

2.1 VMT

- Related Inputs

................................ ................................ ................................ ......... 3

2.1.1 Road Type

................................ ................................ ................................ ................. 3

2.1.2 Annual VMT

................................ ................................ ................................ ............. 4

2.1.3 Monthly, Daily, and Hourly VMT

................................ ................................ ............ 4

2.2 Source

- Related Inputs

................................ ................................ ................................ ...... 5

2.2.1 Source Type Population

................................ ................................ ............................ 6

2.2.2 Age Distribution

................................ ................................ ................................ ........ 6

2.3 VHT

- Related Inputs

................................ ................................ ................................ ......... 6

2.3.1 Ramp Fractions

................................ ................................ ................................ ......... 7

2.3.2 Average Speed Distribution

................................ ................................ ...................... 7

2.4 Fuel

- Related Inputs

................................ ................................ ................................ .......... 8

2.4.1 Alternative Vehicle Fuels and Technology (AVFT)

................................ ................ 8

2.4.2 Fuel Supply

................................ ................................ ................................ ............... 8

2.4.3 Fuel Formulation

................................ ................................ ................................ ....... 8

2.5 Meteorology

................................ ................................ ................................ ..................... 9

2.6 Inspection and Maintenance (I/M) Programs

................................ ................................ . 10

2.7 On

- Road Retrofits

................................ ................................ ................................ .......... 10

3 Methodology: Paved and Unpaved Road Dust

................................ ................................ ...... 10

3.1 Road Dust Emission Factor

................................ ................................ ............................ 11

3.2 Vehicle Miles Traveled

................................ ................................ ................................ .. 11

3.3 Precipitation Data

................................ ................................ ................................ ........... 12

3.4 Average Vehicle Weight by Roadway Type

................................ ................................ .. 12

3.5 Silt Loading

................................ ................................ ................................ .................... 13

3.6 Unpaved Road Dust Emissions

................................ ................................ ...................... 14

4 Results

................................ ................................ ................................ ................................ .... 14

4.1 On

- Road Mobile Source Emission Estimates

................................ ................................ 14

4.2 Paved and Unpaved Road Dust Emission Estimates

................................ ...................... 15

5 Quality Control and Quality Assurance

................................ ................................ ................. 16

6 Conclusion

................................ ................................ ................................ ............................. 17

References

................................ ................................ ................................ ................................ ..... 18Base

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iv Appendix A. Crossw alk between COMPASS TDM Road Types, FHWA Roadway Types, and MOVES Roadway Types

................................ ................................ ................................ .............. 19
Appendix B Crosswalk between ATR Length Bins, FHWA Vehicle Classes and MOVES Source Types

................................ ................................ ................................ ................................ . 21
Appendix C ITD Statewide Vehicle Classification Data

................................ ............................. 23



### List of Figures

Figure 1. MOVES input files and groups.

................................ ................................ ...................... 2
Figure 2. Meteorological and precipitation observation sites in Ada and Canyon Counties.

......... 9



### List of Tables

Table 1. MOVES road type descriptions.

................................ ................................ ....................... 3
Table 2. MOVES source type descriptions.

................................ ................................ .................... 3

Table 3. TDM

- based annual vehicle miles traveled. a

................................ ................................ ..... 4
Table 4. Crosswalk between MOVES source types and data sources f or source

- related MOVES input parameters.

................................ ................................ ................................ .. 5
Table 5. MOVES speed bins.

................................ ................................ ................................ .......... 7

Table 6. E10 market share.

................................ ................................ ................................ ............. 9

Ta ble 7. Days with at least 0.01 inches of rain in Ada and Canyon Counties.

............................. 12
Table 8. Average vehicle weight by vehicle type.

................................ ................................ ........ 13
Table 9. Silt loadings used for paved road emission factor calculation.

................................ ....... 13

Table 10. Annual on

- road emissions in the Treasure Valley.

................................ ....................... 14
Table 11. Daily average on

- road emissions in the Treasure Valley during the ozone season (summer).

................................ ................................ ................................ .......................... 15
Table 12. Daily average on

- road emissions in the Treasure Valley during the PM season (winter).

................................ ................................ ................................ ............................. 15
Table 13. Annual paved road dust emissions in the Treasure Valley.

................................ .......... 15
Table 14. Daily average paved road dust emissions in the Treasure Valley during the ozone season (summer).

................................ ................................ ................................ .............. 16
Table 15. Daily average paved road d ust emissions in the Treasure Valley during the PM season (winter).

................................ ................................ ................................ ................. 16
Table 16. Annual unpaved road dust emissions in the Treasu re Valley.

................................ ...... 16Base

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### Abbreviations, Acronyms, and Symbols

ATR automatic traffic recorder

AVFT alternative vehicle fuel s and technology

BPR Bureau of Public Roadways

CBD central business district

CNG compressed natural gas

CO carbon monoxide

COMPASS Community Planning Association of Southwest Idaho

DEQ Idaho Department of Environmental Quality

DMV Idaho Department of Motor Vehicles

E10 fuel blend of 10% ethanol and 90% gasoline

EI emission s inventory

EPA US Environmental Protection Agency

ERG Eastern Research Group

FHWA Federal Highway Administration

HOV high

- occupancy vehicle

HPMS Highway Performance Monitoring System

I/M inspection and maintenance

ITD Idaho Transportation Department

MOVES Motor Vehicle Emissions Simulator

m ph miles per hour

NH 3 ammonia

NO

x nitrogen oxides

PM particulate matter

PM 10 particulate matter with a diameter less than 10 microns

PM 2.5 particulate matter with a diameter less than 2.5 microns

SH state highway

SIP state implementation plan

SO 2 sulfur dioxide

TDM travel demand model

TVRDS Treasure Valley r oad d ust s tudy

US United States

VHT vehicle hours traveled

VIN vehicle identification number

VMT vehicle miles traveled

VOC volatile organic compoundBase

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1 

## 1 Introduction

The State of Idaho contracted with Eastern Research Group (ERG) and Environ International Corporation (Environ) to complete state implementation plan ( SIP )

- quality emission s inventor ies (EI s ) for the Treasure Valley of Idaho

. ERG and Environ jointly completed the 2008, 2015

, and

2023 EI s (ERG and Environ 2010) using the MOBILE6.2 model for on

- road mobile source

emissions. The Idaho Department of Environmental Quality ( DEQ ) contracted with ERG and

Environ to prepare th e s e EI s to support renewal of t he n orthern Ada County PM 10 m aintenance

p lan and other projects. 1 As a result, Elmore and Canyon Count ies are included in the EIs.

Since completi ng th e s e EI estimates

, the US Environmental Protection Agency ( EPA ) has released a new mobile source emissions model, t he Motor Vehicle Emissions Simulator (MOVES2010a) (EPA 2011 a )

. In an effort to ensure that t he State of Idaho is using the most

recent emissions models for SIP and m aintenance p lan development and for developing motor vehicle emission budgets for subsequent conformity determinations, the mobile source portion of

each EI was redone using the MOVES2010 a emissions model (hereafter referred to simply as MOVES)

, and the paved road dust emissions were developed using the latest EPA

- recommended (AP

- 42) method (EPA 2011 b ). Unpaved road dust emission estimates included in the 2010 EI were used as reported (ERG and Environ 2010 ). This report details the methodolog ies and results

for the MOVES on

- road emissions modeling and road dust computations.

MOVES is the EPA

- designated model for on

- road mobile EI development for SIP s and

m aintenance p lans and for Federal Highway Administration (FHWA) transportation conformity

determinations. The on

- road mobile source EI was developed using MOVES according to the Technical Guidance on the Use of MOVES2010 for Emission Inventory Preparation in State Impl ementation Plans and Transportation Conformity (EPA 2010)

. The results will be reviewed through an interagency consultation process.

Paved and unpaved road dust emission estimates were included in the 2008, 2015

, and 2023 Treasure Valley EI s (ERG and Environ 2010). For th e PM 10 m aintenance p lan u pdate, new paved road dust emissions estimates were developed by DEQ ; however

, u npaved road dust

emissions estimates included in this update were not changed from those presented in the 2008, 2015, and 2023 Treasure Valley EI s (ERG and Environ 2010).

The Northern Ada County PM 10 Maintenance Area only includes the northern, populated portion of Ada County. The southern portion is largely unpopulated, but all emission estimates represent the entire county . The EI for the entire county provides a conservative surrogate for emissions in the Northern Ada County M aintenance A rea. In addition, the adjacent Canyon County is not

within the PM 10 maintenance area

. H owever
, since this mobile source EI must meet other purposes, such as photochemical modeling, and since the airshed today includes Canyon County, the Canyon County emissions are retained in this report.

1 PM 10 is particulate matter with a n aerodynamic diameter less than 10 microns

. PM 2.5 , discussed later in this report,
has a n aerodynamic diameter less than 2.5 microns.Base

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2 

## 2 Methodology: MOVES Input Database Development

To operate the MOVES model at the county

- level as required by EPA for SIP

- level EIs

, DEQ develop ed an input database for each specific combination of inputs. This section discusses the

assum ptions, sources of input information

, and calculation methodologies involved in developing

SIP

- level MOVES input databases.

Figure 1 describes the required MOVES input databases , grouped by common data source. For example, inputs related to vehicle miles t raveled ( VMT ) (top box in Figure 1 )

— such as road type

distribution and monthly, daily

, and hourly traffic profiles

— require detailed information on the

VMT within the modeling domain. DEQ prepared i nput files for each group using a combination

of (primarily) local data and national default value s w h ere good local data were not available

. This section discusses the creation of each input. The input data file format under discussion is provided after each section heading for clarification.

Figure 1. MOVES input files and groups

.Base

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3 

### 2.1 VMT

- Related Inputs

VMT inputs describe the distance traveled on different roadways by the various source types (vehicles). VMT

- related inputs include road type distribution and VMT (annual, monthly, daily, and hourly estimates ). The road type VMT distribution data set was developed from the Ada/Canyon County travel demand model (TDM)

, and the monthly, week day /week end , and hourly VMT profiles were developed from permanent a utomatic t raffic r ecorders (ATRs)

. The TDM results for the 2008 base year were prepared by the Community Planning Association of Southwest Idaho ( COMPASS ) in 2009 and updated in early 2011 to reflect the recently released

2010 census data. This 2011 update allowed COMPASS t o make some minor adjustments in the 2008 model to reflect real variations in population shifts in some areas reflected in the first new

census tract data in 10 years (M. Waldinger, COMPASS, personal communication , 2011 )

.

MOVES road types and source ( vehicle) types are defined in Table 1 and Table 2

.

Table 1

. MOVES road type descriptions

.
R oad Type Desc ription

1 Off

- Network

2 Rural Restricted Access

3 Rural Unrestricted Access

4 Urban Restricted Access

5 Urban Unrestricted Access

Table 2

. MOVES source type descriptions

. MOVES Source Type Description

11 Motorcycle

21 Passenger Car

31 Passenger Truck

32 Light Commercial Truck

41 Intercity Bus

42 Transit Bus

43 School Bus

51 Refuse Truck

52 Single Unit Short

- haul Truck

53 Single Unit Long

- haul Truck

54 Motor Home

61 Combination Short

- haul Truck

62 Combination Long

- haul Truck

2.1.1 Road Type

Road t ypeDistribution(sourceTypeID, roadTypeID, roadTypeVMTFraction)

The road type distribution describes the fraction of fleet miles driven on each of the four applicable MOVES road types (rural restricted, rural unrestricted, urban restricted, and urban unrestricted) within the modeling domain for each source (vehicle) type

. Road type distributionBase

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4 inputs were derived from TDM outputs provided by COMPASS

, annual Highway Performance Monitoring System ( HPMS ) VMT by FHWA road type , and link

- level Idaho Transportation Department (ITD) ATR data

. A crosswalk table in Appendix A shows the relationships between

COMPASS TDM road types , the HPMS/FHWA road types, and the MOVES roadway types.

ITD ATR data were aggregated by county and used to allocate the annual VM T for each source

type to road types. When the annual road distributions were complete for the FHWA road types, the distributions were aggregated into the four MOVES road types.

2.1.2 Annual VMT HPMSVTypeYear(HPMSVtypeID, yearID, HPMSBaseYearVMT, baseYearOffNet VMT)

Annual VMT is the yearly VMT for each HPMS vehicle type for each count y in the domain. ITD ATR data were used to generate a weekday/ weekend ratio and fleet mix for each roa d type

, which were then applied to COMPASS TDM annual average weekday VMT outputs to estimate

annual VMT for base and future years

.

Comparing annual VMT attributed to local roads from the TDM output to annual local road

VMT from ITD fuels sales data indicated that the TDM underestimates VMT from local roads , a common trait of TDM models nationwide

. To compensate for this, DEQ scaled up TDM local

road VMT to match ITD HPMS estimates. For base and future years, annual local road VMT

estimates were adjusted up using the same scaling factor. The final TDM

- based VMT after the

local road reconciliation are summarized in Table 3

.

Table 3

. TDM

- based annual vehicle miles trave led. a

County Year Vehicle Miles Trave led

Ada 2008 3,203,969,729

Ada 2015 3,887,965,879

Ada 2023 5,533,619,325 Canyon 2008 1,574,168,589 Canyon 2015 1,992,190,855
Canyon 2023 3,164,270,684

a A fter adjustment of local road vehicle miles trave led to match HPMS

2.1.3 Monthly, Daily, and Hourly VMT MonthVMTFraction(source t ypeID, isLeapYear, monthID, monthVMTFraction) DayVMTFraction(sourceTypeID, monthID, roadTypeID, dayID, dayVMTFraction) HourVMTFraction(sourceTypeID, roadTypeID, dayID, hourID, hourVMTFraction)

Temporal distribution profiles further divided the sour ce type annual VMT into finer time

increments. Temporal profiles were derived from ATR data and annual VMT by FHWA road

type , the latter of which were calculated from TDM outputs provided by COMPASS.

ATR data contain hourly vehicle counts for each of 5 length categories or “ bin s

. ” Counts for each length bin were converted to temporal distributions for each MOVES vehicle type and roadway type using a c rosswalk scheme developed based on discussi ons with ITD and 2007

– 2009 Idaho statewide vehicle classification data ( Scott Fugit , ITD , personal communication).

The final crosswalk table

, which maps ATR length bins to MOVES vehicle type s
, is provided in Appendix B

, and the 2007

– 2009 classification data are provided in Appendix C. Neither ATRBase

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5 data nor FHWA vehicle classification data distinguish between personal or commercial trips

, and long or short

- haul truck trips , so it was necessary to use national default fractions available in the

MOVES model to make the final splits from FHWA classes to MOVES vehicle types in these

areas

. For each ATR site, a full year of ATR data were processed. Hourly, weekday / weekend, and monthly statistics were calculated for each vehicle type. Finally, ATR sites were grou ped based on MOVES road types

, and each site was weighted equally in constructing the final temporal profiles. For the purposes of the MOVES modeling and paved road dust calculations,

w inter ( particulate matter, or PM) season is defined as November 1

– February 29 , and the

summer or “non winter” season is defined as April 1

– October 31.

Future

- year temporal profiles for each road type were developed from the TDM output using the

base

- year ATR

- based temporal profiles along with future

- year VMT.



### 2.2 Source

- Related Inputs

This group of inputs includes s ource t ype p opulation and a ge d istribution. Source

- related inputs describe and group the vehicles in the modeling domain and are compile d using a variety of data

sources ( Table 4 )

. The fleet mix distribution is a key component of on

- road mobile source

emissions.

In March 2011, DEQ decoded individual Idaho Department of Motor Vehicles ( DMV ) registration records of vehicles registered in the Treasure Valley using the Polk v ehicle

i dentification n umber (VIN) d ecoding system . The decoded VINs provide information regarding the vehicle make, model, age, a nd fuel types. This information was then used to develop the MOVES source type population input and fleet age distribution input. An earlier VIN decoding project by Sierra Research (Sierra Research 2006) is used to provide source population dat a for the ye ars prior to 1981.

Table 4

. Crosswalk between MOVES source types and data sources for source

- related MOVES input parameters.

MOVES Source Type Source

- Related Input Data Source

Motorcycle ITD

— DMV Reg istration Database (2011)

, Sierra Research (2006)

Passenger Car ITD

— DMV Registration Database (2011) , Sierra Research (2006)

Passenger Truck ITD

— DMV Registration Database (2011) , Sierra Research (2006)

Light Commercial Truck ITD

— DMV Registration Database (2011) , Sierra Research (2006)

Intercity Bus MOVES Default Database, Annual Local VMT, Sierra R esearch (2006)

Transit Bus ValleyRide

School Bus Idaho Departm ent of Education

Refuse Truck MOVES Default Database, Annual Local VMT, Sierra Research (2006)

Single Unit Short

- haul Truck MOVES Default Database, Annual Local VMT, Sierra Research (2006)

Single Unit Long

- haul Truck MOVES Default Database, Annual Local VMT, Sierra Research (2006)

Motorhome ITD

— DMV Registration Database (2011) , Sierra Research (2006)

Combination Short

- haul Truck MOVES Default Database, Annual Local VMT, Sierra Research (2006)

Combination Long

- haul Truck MOVES Default Database, Annual Local VMT, Sierra Research (2006)Base

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6 2.2.1 Source Type Population SourceTypeYear(yearID, sourceTypeID, sourceTypePopulatio n)

The source type population input describes the types and numbers of vehicles that make up the

fleet. F ive major data sources were used to develop the source type population inputs: VIN

decoded ITD registration data, MOVES national default population and activity data, local activity data derived from TDM output, Valley R ide transit bus fleet data

, and Idaho Department

of Education school bus fleet data ( Table 4 )

.

Direct population data were available for transit buses from ValleyRide and for school buses from the Idaho Department of Education. For motorcycle, passenger car, passenger truck, light commercial truck, and motorhome source types, VIN

- decoded registration data were used to determine vehicle populations.

For all other heavy

- duty source types, a factor was used to estimate the local source type populations using local activity data, MOVES national default activity data, and MOVES national default source type populations (Equation 1)

. ( ) Equation 1. E stimate of vehicle population for source types without local data availabl e.

Equation 1 was used to estimate the MOVES source type population inputs for most heavy

- duty vehicle type s for Ada and Canyon C ounties , except transit buses, school buses

, and motorhomes

. Future

- year source typ e populations were estimated using Equation 1 by substituting local

future

- year annual VMT for base

- year annual VMT , future

- year national default population for

base

- year national default population, and future

- year national default VMT for base

- year national default VMT

.

2.2.2 Age Distribution AgeDistribution( S ourceTypeID, Y earID, A geID, A geFraction)

This input provides an age profile of the fleet. Separate age distributions were developed for Ada and Canyon C ounties using VIN

- decoded vehicle registration data, pre

- 1981 vehicle population

data f rom an earlier VIN

- decoder study (Sierra Research 2006), transit bus fleet age data from ValleyRide, and school bus fleet age data from the Idaho Department of Education. The same age distribution inputs were used for base and future years.



### 2.3 VHT

- Related Inputs

Vehicle hours traveled ( VHT ) inputs capture the time spent on roads by vehicles. This group of inputs includes ramp fractions and average speed distribution

.Base

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7 2.3.1 Ramp Fractions RampFraction(roadTypeID, rampFraction)

Ramp fraction defines the portion of VHT on roadways that contain entrance and exit ramps for restricted access roadways. Base

- and future

- year ramp fractions for urban and rural freeways were calculated by aggregating VHT on ramps an d restricted access roadways using TDM output

from COMPASS , then dividing ramp VHT by total restricted access roadway VHT to get the fraction of restricted access VHT attributed to ramps. Urban ramp fractions are 0.085 for winter

season and 0.086 for summe r season , while rural ramp fractions are 0.010 for both season s in Ada and Canyon Counties.

2.3.2 Average Speed Distribution AverageSpeedDistribution(sourceTypeID, roadTypeID

, hourDayID

, avgSpeedBinID, avgSpeedFraction )

The average speed distribution allocates the different source types (vehicles) for each roadway

type to 16 speed bins ranging from 0 to > 7 5 miles per hour ( mph ) ( Table 5 ). This input reflects levels of congestion on roadways. Average speed distributions were developed from TDM average daily traffic counts for each roadway segment and hourly traffic count statistics developed from detailed ATR traffic count data provided by ITD.

Table 5

. MOVES speed bins.

avgSpeedBinID avgBinSpeed avgSpeedBinDesc

1 2.5 speed < 2.5 mph

2 5 2.5 mph ≤ speed < 7.5 mph

3 10 7.5 mph ≤ speed < 12.5 mph

4 15 12.5 mph ≤ speed < 17.5 mph

5 20 17.5 mph ≤ speed <22.5 mph

6 25 22.5 mph ≤ speed < 27.5 mph

7 30 27.5 mph ≤ speed < 32.5 mph

8 35 32.5 mph ≤ speed < 37.5 mph

9 40 37.5 mph ≤ speed < 42.5 mph

10 45 42.5 mph ≤ speed < 47.5 mph

11 50 47.5 mph ≤ speed < 52.5 mph

12 55 52.5 mph ≤ speed < 57.5 mph

13 60 57.5 mph ≤ speed < 62.5 mph

14 65 62.5 mph ≤ speed < 67.5 mph

15 70 67.5 mph ≤ speed < 72.5 mph

16 75 72.5 mph ≤ speed

The hourly ATR

- based traffic count profiles for each roadway type were used to estimated hourly volume on each segment, and the modified Bureau of Public Roadways (BPR) volume/capacity curve (Equation 2) was then used to develop the average speed distribution

database for each hour. ( ( ) ) Equation 2

. BPR CurveBase

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8 Where A and B are local coefficien ts used in the TDM as provided by COMPASS.

Base

- and future

- year average speed distributions were developed for all four MOVES road types using TDM base and future

- year outputs developed by COMPASS for the Treasure Valley

and detailed ATR data provided by ITD

.



### 2.4 Fuel

- Related Inputs

This group of inputs includes data regarding alternative vehicle fuels and technology (AVFT), fuel supply, and fuel formulation.

2.4.1 Alternative Vehicle Fuels and Technology (AVFT) AVFT(sourceTypeID, modelYearID, fuelTypeID, engTechID, fuelEngFraction)

AVFT i nput files in MOVES allow the user to assign source type activity by model year to vehicles with different fuel and/or engine technologies. Ada and Canyon C ounties were modeled using a custom AVFT input file derived from VIN

- decoded registration data. The same AVFT input was used for base and future years.

2.4.2 Fuel Supply FuelSupply(countyID, fuelYearID, month g roup id , fuel f ormulation id

, markets hare,

market s hare cv )

National default fuel supply inputs were used for all source types except transit buses

. A large portion of the transit bus fleet in the Treasure Valley operates on compressed natural gas (CNG). For this reason, CNG fuels were included in base

- and future

- year modeling.

2.4.3 Fuel Formulation FuelFormulation(fuel

f ormulation id

, fuelSubtypeID, RVP, s ulfurLevel, ETOHVolume, MTBEVolume, ETBEVolume, TAMEVolume, aromaticContent, olefinContent, benzeneContent, e200, e300, volToWtPercentOxy, B ioDieselEsterVolume, C etaneIndex, PAHContent)

With the exception of 10 % ethanol in gasoline ( E10 ) , MOVES nat ional default fuel formulations

were used as base

- year inputs for each county

. These default values were judged to be reasonable based on local knowledge

, except for the E10 market share. The base

- year E10 market share w as updated with information provided by fuel suppliers ( Table 6 ). Future

- year runs used default

values since the E10 market share is known to be nearly 100% at the present (late 2011) and is expected to remain so in the foreseeable future, consistent with the MOVES default database.Base

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9 Table 6

. E10 market share.

Year Market Share

2008 0.68

2015 1.00 ( National Default )

2023 1.00 ( National Default )



### 2.5 Meteorology
ZoneMonthHour(monthID, zoneID, H ourID, temperature, relHumidity)

The meteorology input compiles the average hourly temperature and relative humidity data for each county

. Base

- and future

- year inventories were modeled using average hourly temperature and relative humidity data by county for each month from a representative weather station for each county . Ada County is represented by the National Weather Service station at the Boise Air Terminal and Canyon County is represented by the data set from the Caldwell Industrial Airport ( Figure 2 ).

Figure 2. Meteorolog ical and precipitation observation s ites in Ada and Canyon C ounties.Base

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10 

### 2.6 Inspection and Maintenance (I / M) Programs
IMCoverage(polProcessID, stateID, countyID, yearID, sourceTypeID, fuelTypeID, IMProgramID, inspectFreq, testStandardsID, begModelYearID, endModelYearID, useIMyn, complianceFactor)

Inspection and maintenance ( I / M ) programs require registered vehicles to undergo periodic

emissions tests. During the 2008 base year, Ada County had an active I / M program and was

modeled as such. Canyon County did not have an active I / M program during 2008 and w as modeled without any I

/ M program active in MOVES.

For 2015 and 2023 future

- year modeling , Ada and Canyon C ounties were both modeled with

active I / M programs to reflect the implementation of an I / M program in 2010 in Canyon County along with accompanying changes to the Ada County I / M program during the same time frame.



### 2.7 On

- R oad Retrofits

On

- roadRetrofits( P ollutant, P rocess, F uel, S ource, I nitialCalendarYear, F inalCalendarYea r,
I nitialModelYear, F inalModelYear, F raction / Year, F ractionEffective)

Neither Ada nor Canyon County use on

- road retrofits. Therefore, both counties were modeled

with out on

- road retrofits specified in the MOVES input database.



## 3 Me thodology: Paved and Unpaved Road Dust

Fugitive dust from paved and unpaved roads is a significant source of PM emissions. In general,

the factors that affect paved road dust emissions include the weight of the vehicles that drive on the roadway surface, vehicle spe ed, fine particle (silt) loading on the roadway surface available for entrainment, and precipitation on the roadway that decreases road dust emissions. Unpaved road dust emission estimates are used directly as reported in the area sources categ ory of the Treasure Valley base

- year and future

- year EIs (ERG and Environ 2010)

. Paved road dust emission estimates were developed by DEQ in 2011 to replace the ERG/Environ (2010) estimates, as described in the following sections.

In 2010, the 2008, 2015, and 2023 paved road dust emission estimate s were completed for the Treasure Valley as part of the 2008 SIP

- level EI (ERG and Environ 2010). The paved road dust

EIs were completed using a n emission factor methodology and local data developed during the Treasure Valley r oad d ust s tudy (TVRDS) (Ety e mezian et al. 2002). DEQ subsequently learned

that the TVRDS paved road dust emissions estimates were based on a calibration origina lly established for unpaved roads , not paved roads

. I n subsequent studies when Etyemezian et al. recalibrated the system for paved roads , they determined that the 2002 TVRDS emission factor measurements in the Treasure Valley were “unreasonably high” (Langston et al

. 2008). As a result, DEQ abandoned the 2002 TVRDS emission factors and re calculated Ada and Canyon County paved road dust emissions using a new emission factor equation published in January

2011 by EPA as th e agency’s recommended method in AP

- 42 Compilation of Air Pollutant

Emission Factors (EPA 2011 b , section 13.2.1 ). However, since the silt loadings measured by Etyemezian et al. in the TVRDS are based on local conditions and are somewhat more

conservative than default silt loadings published in the January 2011 AP

- 42 method, the local siltBase

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11 loadings were retained rather than using the default loadings. This approach is described in the following sections.



### 3.1 Road Dust Emission F actor

Paved road dust emissions were computed on a monthly basis using Equation 3 from the January

2011 AP

- 42 Compilation of Air Pollutant E mission F actor s (EPA 2011 b , section 13.2.1 ). This form of the equation accounts for the dust suppression effect of precipitation that occurs during

each month.

E ext = [ k (sL) 0.91 x (W) 1.02 ] (1

– P / 4 N ) Equation 3 . Paved road dust

emissions

.

w here

E ext = PM 10 or PM 2.5 emission factor in the same units as k

k = particle size multiplier (1.0 for PM 10 ) ( g rams /VMT )

sL = road surface silt loading (grams per square meter)

W = average weight of the vehicles traveling the roa d (tons)

P = number of “wet” days with at least 0.254 m illi m eters (0.01 in ches ) of precipitation during the averaging period (daily)

N = number of days in the averaging period (e.g.

, 28, 29, 30 , or 31 for monthly)

The emission s for each county and each roadway type are compute d as the product of the

emission factor and the VMT on each roadway type and in each county. Therefore, for each roadway type, each county

, and each month in the modeling period, VMT , road surface silt loading, average weight of the vehicles traveling the road, and the number of days with at least

0.254 m illi m eters (0.01 in ches ) of precipitation must be determined.



### 3.2 Vehicle Mile s Traveled
To generate paved road mobile emissions estima tes for each month, daily averaged VMT is required. The VMT was generated from the TDM outputs provided by COMPASS in spring

2011. The TDM for the base year 2008 was updated by COMPASS based on the newly released 2010 census information just prior to use in these mobile source emissions calculations. Prior to the 2010 census update, the areas of growth in the TDM model were based on projections from the 2000 census, so the 20 10 census update provided verification and some minor corrections to

the demo graphic basis of the TDM model (M. Waldinger, COMPASS, personal communication, 2011).

S ince local roads are not captured in detail by the TDM , the local road V MT were adjusted to be

consistent with HPMS

- based local road VMT estimates. The adjustment to the HPMS VMT is normally applied in SIP inventories to ensure that the most accurate basis is used for total

VMT

— the total fuel sales volume at the county level

. The annual VMT totals used in the road

dust calculations are the same as those used in the MOVES modeling, summarized in Table 3

,

s ection 2.1.2

.Base

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- Year Emission s Inventory

12 

### 3.3 Precipitation D ata
Precipitation is used in Equation 3 to adjust the road dust emissions for rainy days when enough precip itation ( ≥ 0.01 inches) falls to suppress road dust emissions. T he number of days in each

month with at least a trace of precipitation were reported in the ERG and Environ (2010) report and originated from the 2008 precipitation data from the Western Regional Climate Center (WRCC 2009). Data from the Boise Airport Weather Service Forecast Office ( WSFO

No. 1001022) were used for Ada County, while data from the Caldwell Airport Station (No. 101380) were used for Canyon County. The precipitation da ta inputs are presented in Table

7

.

Table 7

. Days with at least 0.01 i nches of r ain in Ada and Canyon Counties.

Month Ada County Canyon County
January 12 10
February 10 8

March 10 8
April 8 7
May 8 6

June 6 5
July 2 2
August 2 2
September 4 3

October 6 5

November 10 9

December 11 10



### 3.4 Average Vehicle Weight by Roadway Type

Average vehicle weight for each roadway type is derived from the vehicle type fraction on each roadway type and average vehicle weight by vehicle type.

Permanent ATR data for Ada and Canyon C ounties were provided by ITD and combined with

statewide FHWA ve hicle classification data from ITD to determine the vehicle type fractions traveling on each roadway type in the modeling domain. The ATR data identifies motorcycles, passenger vehicles

, and two classes of heavy

- duty vehicles by length measurement ; however

, the FHWA vehicle classification statistics by roadway type are needed to provide greater detail in

vehicle classification. The average vehicle weight for each vehicle type was obtained from the

MOVES default database (EPA 2010) as shown in Table 8

. Source type IDs are provided in

Table 2

.Base

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- Year Emission s Inventory

13 Table 8

. Average vehicle weight by vehicle typ e

. SourceType

ID HPMS Vtype ID SourceType Name Source Mass (Metric Tons)

11 10 Motorcycle 0.285

21 20 Passenger Car 1.479

31 30 Passenger Truck 1.867

32 30 Light Commercial Truck 2.060

41 40 Intercity Bus 19.594

42 40 Transit Bus 16.556

43 40 School Bus 9.070

51 50 Refuse Truck 20.684

52 50 Single Unit Short

- haul Truck 7.642

53 50 Single Unit Long

- haul Truck 6.250

54 50 Motor Home 6.735

61 60 Combination Short

- haul Truck 29.328

62 60 Combination Long

- haul Truck 31.404



### 3.5 Silt Loading
General default silt loadings are available in the January 2011 emission factor methodology for paved roads (EPA 2011 b ) ; however

, if local data are available, they are preferred. During the

2002 TVRDS

, silt loading measurements were taken at numerous locations in Ada and Canyon

Count ies . An inquiry to the Ada County Highway District revealed that while there is some

recent movement toward us ing more salt and less sand, there had not been any large shift away from sanding as of 2008, the year of the base inventory

. This information confirmed that while sanding varies with the number of storms each year, the 2008 winter sand ing practices and sand consumption w ere approximately the s ame as those observed in the 2002 period when the

TVRDS was conducted. As a result, the local silt loading measurements made in the TVRDS on local and arterial roadways ( Ety e mezian et al. 2002) were determined to still be applicable and

were used for silt loadings. These loadings are somewhat higher than the default loadings in the January 2011 EPA road dust method but were used as the best available representation of local

conditions and to ensure that the results are conservative. F or safety reasons, Etyemezian et al. (2002) did not ma ke road dust measurements on the interstate, so the default values from the

E PA methodology (EPA 2011 b ) are used in calculations for interstates. Silt loadings used for

this mobile source inven tory are shown in Table 9 below.

Table 9

. Silt loadings used for paved road emission factor calculatio n

.
Road Type Winter Silt Loading

(g/m 2 ) Summer Silt Loading (g/m 2 ) Source

Interstate 0.015 0.015 EPA 2011 b

Arterial 1.9 0.5 Ety e mezian et al. 2002

Local 4 0.4 Ety e mezian et al. 2002

Note : grams per square meter (g/m 2 )Base

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- Year Emission s Inventory

14 

### 3.6 Unp aved Road Dust Emissions

For the PM 10 m aintenance p lan u pdate, unpaved road dust emission estimates from the 2008, 2015, a nd 2023 EIs for the Treasure Valley a irshed (ERG and Environ 2010) were used without adjustment. ERG and Environ obtained u n paved road traffic counts and road segment lengths for the 2008 base ye ar from a survey of the cit y and county road departments in Ada and Canyon

C ounties and estimated annual VMT from that survey. An average speed of 25 mph was assumed for all unpaved roads. Then the unpaved road dust emission estimation methodology used in the TVRDS was adopted, as detailed in the EI report (ERG and Environ 2010). The unpaved road dust emission factor method used by Etyemezian et al. in the TVRDS was based

on unpave d road dust calibrations conduced at Fort Bliss, Texas

, prior to the TVRDS. As a result, DEQ believes that although there were problems with the paved road emission factors (discussed in Section 3, 2 nd paragraph) , the unpaved road dust emission factors fro m the TVRDS should be accurate and reflect the best local data available. Therefore, the unpaved road dust emission estimates developed by ERG and Environ using the TVRDS emission factors were used as reported.



## 4 Results

O n

- road mobile source, paved road dust, and unpaved road dust emissions estimate result s are presented in this section.



### 4.1 On

- R oad Mobile Source Emission Estimate s

On

- road mobile source emissions are reported annually

, as an average ozone season day

, a nd as an average PM season day. The ozone season is defined as April 1

– October 31

, and the PM

season is November 1

– February 29

. This definition matche s other emission sources developed by ERG and E nviron in the EI . On

- road mobile source emissions results from the MOVES

model are shown in Table 10

, Table 11 , and Table 12 as annual total, average ozone season day, and average PM season day, respectively. These emission results include estimates for nitrogen

o xides (NO

x ), sulfur dioxide (SO 2 ), volatile organic compounds (VOC), carbon monoxide (CO), particular matter, and ammonia (NH 3 ). The PM 10 and PM 2

. 5 emission estimates in these tables

include particulate matter from direct exhaust, brake wear

, and tire wear and do not include paved and unpaved road dust.

Table 10

. Annual on

- road emissions in the Treasure Valley.

Year County NO
x SO 2 VOC CO PM 10 PM 2.5 NH 3 (tons per year)

2008

Ada 9775. 4 67. 4 4182. 3 47168.3 412. 7 330. 4 152.9

2015 5856.6 33.4 2939.7 39263.4 28 3.0 193.0 126.4

2023 4306.4 42.0 2396. 8 38771.8 285.2 157.1 146.6

2008
Canyon 5847.8 3 5

. 0 3202. 1 36404. 4 258. 2 212. 1 81.8

2015 3870.5 17.7 2177. 2 27974. 3 178. 4 127. 6 74.4

2023 3273.6 25.1 1935.0 27684.6 191.5 112.3 95.0Base

- and Future

- Year Emission s Inventory

15 Table 11

. Daily average on

- road emissions in the Treasure Valley during the ozone season (summer).

Year County NO X SO 2 VOC CO PM 10 PM 2.5 NH 3 (tons per day)

2008

Ada 28. 5 0.20 10.9 110. 9 1.09 0.86 0.45

2015 16.9 0.10 7. 7 83.8 0.74 0.48 0.37

2023 12. 4 0.12 6. 6 78.5 0.75 0.37 0.43

2008
Canyon 16.7 0.10 8.4 87. 9 0.65 0.52 0.24

2015 11.0 0.05 5. 7 61.1 0.45 0.31 0.22

2023 9.2 0.07 5.2 57. 2 0.49 0.26 0.28

Table 12

. Daily average on
- road emissions in the Treasure Valley during the PM season (winter).

Year County NO X SO 2 VOC CO PM 10 PM 2.5 NH 3 (tons per day)

2008

Ada 24.0 0.16 12.30 156. 4 1.19 0.98 0.38

2015 14. 7 0.08 8.69 144. 3 0.83 0.61 0.31

2023 10.9 0.10 6.57 149.7 0.84 0.53 0.36

2008

Canyon 14. 8 0.09 9.28 117.1 0.80 0.67 0.20

2015 9.9 0.05 6.45 100.6 0.55 0.42 0.19

2023 8.5 0.06 5.46 105. 3 0.59 0.39 0.24



### 4.2 Paved and Unpaved Road Dust Emission Estimate s
Paved road dust emissions are reported annually, as an average ozone season day

, and as an average PM season day ( Table 13 through Table 15 ). Unpaved road dust is reported only as an

annual total ( Table 16 )

.

Table 13

. Annual paved road dust emissions in the Treasure Valley.

Year County PM 10 PM 2.5 (tons per year)

2008

Ada 7501 428

2015 9164 522

2023 13243 755

2008
Canyon 4154 237

2015 5211 297

2023 8417 480Base

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- Year Emission s Inventory

16 Table 14

. Daily average paved road dust emissions in the Treasure Valley during the ozone season (summer).

Year County PM 10 PM 2.5 (tons per day)

2008

Ada 10.4 0.6

2015 12.4 0.7

2023 17.9 1.0

2008

Canyon 5.2 0.3

2015 6.6 0.4

2023 10.6 0.6

Table 15

. Daily average paved road dust emissions in the Treasure Valley during the PM season (winter).

Year County PM 10 PM 2.5 (tons per day)

2008

Ada 34.8 2.0

2015 43.1 2.5

2023 62.4 3.6

2008

Canyon 19.9 1.1

2015 25.2 1.4

2023 40.7 2.3

Table 16

. Annual unpaved road dust emissions in the Treasure Valley.

Year County PM 10 PM 2.5 (tons per year)

2008

Ada 965.8 55.1

2015 841.5 48.0

2023 718.8 41.0

2008
Canyon 165.4 9.4

2015 165.4 9.4

2023 165.4 9.4



## 5 Quality Control and Quality Assurance

Quality control was achieved by a quality assurance check of each set of inputs by a team member not directly involved with developing the input. In general, each input was checked for internal consistency, compared with national defaults, and assessed for reasonableness. Input data and outputs were graphed and analyzed to ensure that the expected vehicle population, roadway activity

, and seasonal patterns were obt ained and that differences between these inputs

and those of the national default data set for these counties were understood and justified

. Paved road dust inputs and computations were checked for accuracy and reasonableness.Base

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- Year Emission s Inventory

17 

## 6 Conclusion

On

- road mobile sources of particulate matter and secondary aerosol precursors represent the most signif

icant source of particulate matter pollution in the Treasure Valley. Both the on

- road mobile emissions and paved road dust components of the Treasure Valley EI were revised by DEQ in 2011 to ensure that the n orthern Ada County PM 1 0 m aintenance p lan renewal would be

as up

- to

- date and accurate as possible. This revision was made necessary by the advent of new

EPA

- recommended models for on

- road emissions (MOVES2010a) and for paved road dust (EPA 2011 a ). By completing these updates for the n orthern Ada County PM 10 m aintenance p lan renewal, DEQ ensured that the conformity determinations for years to come will be made on the same basis as the motor vehicle emission budgets and that art ificial method

- caused differences

will be minimized.

Trends indicate that motor vehicle exhaust and evaporative emission s will decreas e in the foreseeable future even though the VMT is projected to increase. On the other hand, paved road

dust emissions are projected to increase roughly proportion ally to VMT

.Base

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- Year Emission s Inventory

18 

## References

EPA (US Environmental Protection Agency). 2010. Technical Guidance on the Use of MOVES2010 for Emission Inventory Preparation in State Implementation Plans and Transportation Conformity

. Washington, DC: EPA, Office of Transportation and Air Quality

, Transportation and Regional Programs Division. EPA

- 420

- B

- 10

- 023.

EPA (US Environmental Protection Agency) . 2011 a . "MOVES (Motor Vehicle Emission Simulator). " Available at: http://www.epa.gov/otaq/models/moves/index.htm

.

EPA (US Environmental Protection Agency). 2011b. AP

- 42 Compilation of Air Pollutant

Emission Factors

. Accessed October 2011 at : http://www.epa.gov/ttn/chief/ap42/index.html

.

ERG and Environ (Eastern Research Group and Environ International Corporation)

. 2010. “2008, 2015, and 2023 Emission Invento ries for the Treasure Valley Airshed.” Cordova,

CA: ERG and Environ

.

Etyemezian V., H. Kuhns, J. Gillies, M. Green, J. Chow, S. Kohl, and J. Watson. 2002. The Treasure Valley Road Dust Study . Las Vegas, NV: Desert Research Institute.

Langston R., S. Russell, R.S. Merle, D. Hart, V. Etyemezian, H. Kuhns, J. Gillies, D. Fritz,

K. Bumiller, and D. James. 2008

. The Preferred Alternative Method for Measurin g Paved Road Dust Emissions for Emissions Inventories : Mobile Technologies vs. The

Traditional AP

- 42 Methodology

. In: 16th Annual International Emissions Inventory

Conference.

Sierra Research

. 2006. Develop ment of Fleet Characteristics Data for the Idaho On

- Road Motor

Vehicle Fleet

. Sacramento, CA: Sierra Research. SR2006

- 01

- 01.

WRCC ( Western Regional Climate Center )

. 2009. Accessed from http://www.wrcc.dri.edu/ in

2009.Base

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- Year Emission s Inventory

19 

## Appendix A

. Crosswalk between COMPASS TDM Road Types, FHWA R oadway T ypes , and MOVES Roadway Types

COMPASS Road Type

ID COMPASS Road Type

Descriptions Area Type FHWA

Road Type
Code FHWA Road

Type Description MOVES

Road Type MOVES

Road Type

Des cription

Parked vehicles and extended idle are not included in COMPASS or FHWA road types 1 Off Network

1 Interstate or expressway with urban

interchanges (e.g., SH 16) a Rural

01 Rural Principal

Arterial

— Interstate 2 Rural

Restricted

Access 2 HOV b (not currently in use) Rural

19 Interstate ramps Rural

3 Principal arterial s in CBD c and/or

are one

- way Rural

02 Rural Principal

Arterial

— Other

3 Rural

Unrestricted

Access 4 Expressway with at

- grade

intersections (e.g., Chinden Blvd) Rural

5 Principal arterials in urban areas

(use area of impact) Rural

6 Principal arterial in rural areas (use

area of impact) Rural

7 Minor arterials in CBD and/or are

one

- way Rural

06 Rural Minor

Arterial 8 Minor arterials (not currently in use) Rural

9 Minor arterials in urban areas (use

area of impact) Rural

10 Minor arterials in rural areas (use

area of impact) Rural

11 Rural minor arterials Rural

12 Collectors in CBD and/or are one

way Rural

07 Rural Major
Collector 13 Collectors in urban areas (use area

of impact) and for subdivision access which allow through travel Rural

14 Collectors in rural areas (use area of

impact) Rural

15 Collectors for subdivision access to

local roads and no through travel Rural 08 Rural Minor
Collector

16 Local roads for subdivision access Rural

09 Rural Local 17 Local roads in urban areas added

for circulation Rural

18 Local roads in rural areas added for

circulation Rural

20 Centroid connector Rural

1 Interstate or expressway with urban

interchanges (e.g., SH 16) Urban 11 Urban Principal

Arterial

— Interstate

4 Urban

Restricted

Access 19 Interstate ramps Urban

2 HOV (not currently in use)

Urban 12 Urban Principal

Arterial

— Other Freeways or ExpresswaysBase

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- Year Emission s Inventory

20 COMPASS Road Type

ID COMPASS Road Type

Descriptions Area Type FHWA

Road Type
Code FHWA Road

Type Description MOVES

Road Type MOVES

Road Type

Des cription

3 Principal arterial s in CBD and/or are

one

- way Urban

14 Urban Principal

Arterial

— Other

5 Urban

Unrestricted

Access 4 Expressway with at

- grade

intersections (e.g., Chinden Blvd) Urban

5 Principal arterials in urban areas

(use area of impact) Urban

6 Principal arterial in rural areas (use

area of impact) Urban

7 Minor arterials in CBD and/or are

one

- way Urban

16 Urban Minor

Arterial 8 Minor arterials (not currently in use) Urban

9 Minor arterials in urban areas (use

area of impact) Urban

10 Minor arterials in rural areas (use

area of impact) Urban

11 Rural minor arterials Urban

12 Collectors in CBD and/or are one

way Urban

17 Urban Collector 13 Collectors in urban areas (use area

of impact) and for subdivision access which allow through travel Urban

14 Collectors in rural areas (use area of

impact) Urban

15 Collectors for subdivision access to

local roads and no through travel Urban

16 Local roads for subdivision access Urban

19 Urban Local 17 Local roads in urban areas added

for circulation Urban

18 Local roads in rural areas added for

circulation Urban

20 Centroid connector Urban

a SH = state highway

b HOV = high

- occupancy vehicle

c CBD = central business districtBase

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21 

## Appendix B. Crosswalk between ATR Length Bin s, FHWA
Vehicle Classes

, and MOVES Source Type s

ATR Length

Bin ATR Length Bin

Range FHWA

Vehicle
Class FHWA Vehicle Class

Description MOVES

Source Type ID MOVES Source Types

1 0

– 5.9 ft 1 Motorcycles 11 Motorcycle

2 6

– 22.9 ft 2 Passenger Cars 21 Passenger Car

3 Other Two

- Axle, Four

Tire, Single

- Unit

Vehicles 31 Passenger Truck

32 Light Commercial Truck

3 23

– 39.9 ft 4 Buses 41 Intercity Bus

42 Transit Bus

43 School Bus

5 Two

- Axle, Six

- Tire, Single

- Unit Trucks 51 Refuse Truck

52 Single Unit Short

- haul Truck

53 Single Unit Long

- haul Truck

54 Motor Home

6 Three

- Axle, Single

Unit Trucks 51 Refuse Truck

52 Single Unit Short

- haul Truck

53 Single Unit Long

- haul Truck

54 Motor Home

7 Four

- or

- More Axle, Single

- Unit Trucks 51 Refuse Truck

52 Single Unit Short

- haul Truck

53 Single Unit Long

- haul Truck

54 Motor Home

4 40

– 69.9 ft 8 Four

- or

- Less Axle, Single

- Trailer Trucks 61 Combination Short

- haul Truck

62 Combination Long

- haul Truck

9 Five

- Axle, Single

Trailer Trucks 61 Combination Short

- haul Truck

62 Combination Long

- haul Truck

10 Six

- or

- More Axle, Single

- Trailer Trucks 61 Combination Short

- haul Truck

62 Combination Long

- haul Truck

5 >70 ft 11 Five

- or

- Less Axle,

Multi

- Trailer Trucks 61 Combination Short

- haul Truck

62 Combination Long

- haul Truck

12 Six

- Axle, Multi

- Trailer

Trucks 61 Combination Short

- haul Truck

62 Combination Long

- haul Truck

13 Seven

- or

- More Axle,

Multi

- Trailer Trucks 61 Combination Short

- haul Truck

62 Combination Long

- haul TruckBase

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- Year Emission s Inventory

22 This page intentionally left blank for correct double

- sided printing.Base

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- Year Emission s Inventory

23 

## Appendix C

. ITD Statewide Vehicle Classification DataBase

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- Year Emission s Inventory

24 This page intentionally left blank for correct double

- sided printing.