Overview of EPA's MOtor Vehicle
Emission Simulator (MOVES4)
£% United States
Environmental Protect
Agency
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Overview of EPA's MOtor Vehicle
Emission Simulator (MOVES4)
This technical report does not necessarily represent final EPA decisions
or positions. It is intended to present technical analysis of issues using
data that are currently available. The purpose in the release of such
reports is to facilitate the exchange of technical information and to
inform the public of technical developments.
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
4>EPA
United States
Environmental Protection
Agency
EPA-420-R-23-019
August 2023
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Table of Contents
1. Introduction 4
1.1 MOVES Scope 4
1.2 MOVES Versions 9
1.3 MOVES Uses 11
2. Updates for MOVES4 12
2.1 New Regulations 12
2.2 New Features 12
2.3 Updates to Emission Rates 13
2.4 Updates to Fuel Characteristics, Vehicle Populations and Activity 14
2.5 Updates to User Interface and User Inputs 17
3. MOVES Onroad Algorithms 21
3.1 Running Exhaust and Energy 21
3.2 Start Exhaust 22
3.3 Hotelling Emissions (Extended Idle Exhaust and Auxiliary Power Exhaust) 22
3.4 Crankcase (Running, Start & Extended Idle) 23
3.5 Brake Wear 23
3.6 Tire Wear 23
3.7 Evaporative Permeation 23
3.8 Evaporative Fuel Vapor Venting 24
3.9 Evaporative Fuel Leaks (Liquid Leaks) 24
3.10 Refueling Displacement Vapor and Spillage Loss 24
4. MOVES Nonroad Algorithms 26
4.1 Running Exhaust 26
4.2 Crankcase Exhaust 26
4.3 Refueling Displacement Vapor and Spillage Loss 27
4.4 Fuel Vapor Venting (Diurnal, HotSoak and Running Loss) 27
4.5 Permeation: Tank, Hose, Neck, Supply/Return and Vent Hose 27
5. MOVES Software Structure 28
5.1 MOVES Software Components 29
5.2 MOVES Databases 30
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6. MOVES4.0 Results 32
6.1 Onroad 32
6.2 Nonroad 49
7. MOVES Testing and Evaluation 52
7.1 Peer Review 52
7.2 MOVES Review Work Group 52
7.3 Internal Testing 53
7.4 Beta Testing and Shared "Release Candidate" 53
7.5 Accessibility Testing 53
7.6 MOVES Sensitivity Analysis 53
7.7 Evaluation by Industry-Funded Research Group 53
7.8 Comparisons to Independent Data 54
8. Considerations When Using MOVES 59
9. MOVES4 Documentation 62
10. Acronyms 69
11. References 70
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1. Introduction
EPA's MOtor Vehicle Emission Simulator (MOVES) is a state-of-the-science emissions modeling system
that estimates air pollution emissions for criteria air pollutants, greenhouse gases and air toxics. MOVES
covers onroad vehicles such as cars, trucks and buses, and nonroad equipment such as bulldozers and
lawnmowers. MOVES does not cover aircraft, locomotives, and commercial marine vessels. MOVES
accounts for the phase-in of federal emissions standards, vehicle and equipment activity, fuels,
temperatures, humidity, and emission control activities such as inspection and maintenance (l/M)
programs.
MOVES models calendar year 1990 and 1999 through 2060. Emissions from onroad and nonroad
sources can be modeled at the national or county scale using either model defaults or user-supplied
inputs. Emissions from onroad sources can also be modeled at a more detailed "project" scale if the user
supplies detailed inputs describing project parameters. The onroad module uses operating mode-
specific emission rates to create a consistent approach across all three scales.
MOVES is a bottom-up emissions model that is designed to estimate emissions from separate physical
emission processes depending on the source. MOVES models "fleet average" emissions, rather than
emissions from individual vehicles or equipment types. And MOVES adjusts emission rates to represent
real-world conditions.
This document provides a high-level overview of MOVES4, the latest official version of the MOVES
model. The model and supporting materials are available for free download on the EPA MOVES website,
https://www.epa.gov/moves.
1.1 MOVES Scope
The functional scope of MOVES4 is detailed in Table 1-1 below.
Table 1-1 MOVES Scope
Onroad
Nonroad
Geographic
Scope
U.S. including Puerto Rico and U.S.
Virgin Islands with option to aggregate
to county, state or nation3
Same
Scale
Default (national), county or project
National allocated to state and county
Mode
Inventory (grams) or Rates (grams per
activity)
Inventory (although rates can be
generated with integrated post-processing
scripts)
aNote, California uses the California Air Resources Board EMFAC and nonroad models for regulatory purposes.
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Onroad
Nonroad
Time Span
MOVES estimates hourly emissions for
weekdays and weekends by month
and year for calendar years 1990 and
1999 through 2060, with options to
run at more aggregate levels - day,
month or year.
MOVES estimates daily emissions for
weekdays and weekends by month and
year for calendar years 1990 and 1999
through 2060.
Vehicles and
Equipment
MOVES covers all highway vehicles,
divided into 13 source use types
(source types): motorcycles,
passenger cars, passenger trucks, light
commercial trucks, other buses,
transit buses, school buses, refuse
trucks, single-unit short-haul trucks,
single-unit long-haul trucks,
motorhomes, short-haul combination
trucks and long-haul combination
trucks.
MOVES covers nonroad equipment in 12
broad economic sectors: construction,
agriculture, industrial, lawn & garden
(commercial and residential), commercial,
logging, railroad support (excluding
locomotives), recreational vehicles,
recreational marine (pleasure craft;
excluding commercial marine vessels),
airport service (excluding aircraft), oil
field, and underground mining.
Regulatory
Classes
MOVES covers all onroad regulatory
classes (groups of vehicles with similar
emission standards) ranging from
motorcycles to heavy heavy-duty
vehicles.
Most nonroad equipment is classified by
horsepower bin and engine type-
compression ignition (CI), 2-stroke spark
ignition (SI) and 4-stroke SI. Small SI
equipment is further classified by engine
use (handheld and non-handheld) and
engine displacement.
Fuels
MOVES models emissions from
onroad vehicles using gasoline,b
diesel, compressed natural gas (CNG),
electricity0 and ethanol (E85). Fuels
are further characterized by fuel
subtype and fuel formulation.1,2
MOVES models emissions from nonroad
equipment using gasoline,d nonroad
diesel, marine diesel, CNG, and liquid
propane gas (LPG). MOVES does not
model nonroad equipment powered by
electricity. Fuels are further characterized
by fuel subtype and fuel formulation.3
Road Type
MOVES models onroad vehicles on
rural and urban restricted access and
unrestricted access roads. MOVES also
models vehicle emissions associated
with non-driving operation as "off-
network."
MOVES assigns nonroad emissions to the
"nonroad"road type.
b Including ethanol/gasoline blends of up to 15% ethanol.
c Electric vehicles modelled in MOVES include those powered by batteries and by fuel cells.
d Including ethanol/gasoline blends of up to 10% ethanol.
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Onroad
Nonroad
Pollutants and
Energy
Outputs6
MOVES models a long list of criteria
pollutants and their precursor
emissions/ air toxics,4 greenhouse
gases, and energy use for onroad
vehicles. These include total
hydrocarbons (THC), volatile organic
compounds (VOC), carbon monoxide
(CO), nitrogen oxides (N0X),
particulate matter (PM25& PMi0),
elemental carbon (EC)g, carbon
dioxide (C02), methane (CH4), nitrous
oxide (N20), sulfur dioxide (S02),
ammonia, benzene, ethanol, 1,3
butadiene, formaldehyde,
acetaldehyde, acrolein, polycyclic
aromatic hydrocarbons, metals,
dioxins and furans. Organic gas
emissions can be output in various
aggregations (e.g., total organic gases
and volatile organic compounds), but
"chemical mechanism species" and
PM species such as elemental carbon
from nonroad equipment must be
generated in post-processing.
MOVES models many criteria pollutants
and precursors, air toxics and greenhouse
gases, as well as energy use for nonroad
equipment. These include fuel
consumption, THC, VOC, CO, N0X, PM2 5,
PMio, C02, CH4, S02, ammonia, benzene,
ethanol, 1,3 butadiene, formaldehyde,
acetaldehyde, acrolein, polycyclic
aromatic hydrocarbons, metals, dioxins
and furans. Organic gas emissions can be
output in various aggregations (e.g., total
organic gases and volatile organic
compounds), but "chemical mechanism
species" and PM species such as
elemental carbon from nonroad
equipment must be generated in post-
processing. Note, MOVES does not model
N20 for nonroad equipment.
Emission
Processes
MOVES calculates emissions for
running, start, extended idle (e.g.,
heavy-duty truck hotelling), brake
wear, tire wear, evaporative
permeation, evaporative fuel vapor
venting, evaporative fuel leaks,
crankcase venting, and refueling vapor
and spillage.h
MOVES calculates emissions from running
exhaust, crankcase venting, refueling
vapor and spillage, evaporative tank
permeation, evaporative hose
permeation, and fuel vapor venting from
diurnal, hot soak and running activity.
e A full list of MOVES pollutants is available in the MOVES "Cheat Sheets" found at
https://github.com/USEPA/EPA MOVES Model/blob/master/docs
f The Clean Air Act identifies six criteria pollutants: ground-level ozone, particulate matter, carbon monoxide, lead,
sulfur dioxide, and nitrogen dioxide.
g While not exactly equivalent, elemental carbon is often used as a surrogate for black carbon in GHG estimates.
h MOVES does not include the capability to estimate emissions of re-entrained road dust. To estimate emissions
from re-entrained road dust, practitioners should continue to use the latest approved methodologies.
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Onroad
Nonroad
Activity
Outputs
MOVES can output distance travelled,
source hours, source hours operating,
source hours parked, vehicle
population, starts, extended idle
hours, hotelling diesel auxiliary hours,
hotelling battery or plug-in hours, and
hours spent hotelling with all engines
off.
MOVES can output equipment source
hours, equipment population, average
horsepower, and load factors.
MOVES is intended to model the impact of regulatory standards on fleet-wide emissions. MOVES4
incorporates the regulations listed in Table 1-2 as well as many earlier regulations as explained in the
MOVES technical reports.
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Table 1-2 Recent Mobile Source Regulations Covered by MOVES
National Onroad Rules:
Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine
All onroad control programs
and Vehicle Standards, January 2023
finalized as of the date of
Revised 2023 and Later Model Year Light-Duty Vehicle Greenhouse
the MOVES4.0.0 release,
Gas Emissions Standards, December 2021
including most recently:
Safer Affordable Fuel Efficient (SAFE) Vehicles Rule: March 2020
Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium-
and Heavy-Duty Engines and Vehicles—Phase 2: October, 2016
Tier-3 Vehicle Emissions and Fuel Standards Program: March, 2014
2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas
Emissions and Corporate Average Fuel Economy Standards: October,
2012
Greenhouse Gas Emissions Standards and Fuel Efficiency Standards
for Medium- and Heavy-Duty Engines and Vehicles: September, 2011
Regulation of Fuels and Fuel Additives: Modifications to Renewable
Fuel Standard Program (RFS2): December, 2010
Light-Duty Vehicle Greenhouse Gas Emission Standards and
Corporate Average Fuel Economy Standards; Final Rule for Model-
Year 2012-2016: May, 2010
Final Mobile Source Air Toxics Rule (MSAT2): February, 2007
National Nonroad Rules:
Emissions Standards for New Nonroad Spark-Ignition Engines,
All nonroad control
Equipment, and Vessels: October, 2008
programs finalized as of the
Growth and control from Locomotives and Marine Compression-
date of the MOVES4.0.0
Ignition Engines Less than 30 Liters per Cylinder: March, 2008
release, including most
Clean Air Nonroad Diesel Final Rule - Tier 4: May, 2004
recently:
Ozone Transport
California Advanced Clean Trucks Rule
Commission (OTC)
California Low Emissions Vehicle (LEV) Program
"National Low Emissions
OTC NLEV Program
Vehicle" (NLEV) Program
California Zero Emission Vehicle (ZEV) Sales Mandate
and California Regulations
Adopted Under Clean Air
Act Section 177
These programs are not
incorporated in MOVES
defaults, but may be
modelled by running MOVES
input tools
State and Local Onroad
Inspection and maintenance programs
Programs:1
Fuel programs (also affect gasoline nonroad equipment)
Stage II refueling control programs
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1.2 MOVES Versions
EPA's official public versions of MOVES are characterized as "major" releases when they include
substantial changes to onroad criteria pollutant emissions. "Minor" releases include no substantial
changes to onroad criteria emissions - for example, they may include updates to user interface, changes
to toxic or GHG emissions or updates to nonroad emission rates.
EPA may also develop internal versions of the model for regulatory and analytic support. These versions
typically lack some features required for a public release, but they are made available in relevant
rulemaking dockets and their updates are generally incorporated into the next official public version.
Table 1-3 summarizes the public release history of MOVES and its predecessors, MOBILE and NONROAD.
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Table 1-3: MOVES Version History
Public Releases
Release Date
Key Features
M0BILE1-
MOBILE6.2
1978-2004
• Predecessor to MOVES
• Estimated g/mi onroad emissions
• Increased scope and complexity over time
NONROAD
1998-2010
• Predecessor to MOVES
• Estimated emissions for nonroad sources
MOVES2010
2010
• New structure for onroad only
• Incorporated vehicle activity
• Designed to model at project, county, and national scales
MOVES2010a
2010
• Modeled 2012+ LD GHG rule
MOVES2010b
2012
• Performance improvements
• Improved vapor venting calculations
MOVES2014
2014
• Modeled Tier 3 and 2017+LD GHG rules
• Updated gasoline fuel effects
• Improved evaporative emissions
• Improved air toxics
• Updated onroad activity, vehicle populations and fuels
• Incorporated NONROAD model
MOVES2014a
2015
• Added nonroad VOC and toxics
• Updated default nonroad fuels
• Added new options for user vehicle miles travelled (VMT) input
MOVES2014b
2018
• Improved emission estimates for nonroad mobile sources
• Updated outputs used in air quality modeling
M0VES3
2020
• Updated onroad exhaust emission rates, including HD GHG
Phase 2 and Safer Affordable Fuel Efficiency (SAFE) rules
• Updated onroad activity, vehicle populations and fuels
• Added gliders and off-network idle
• Revised inputs for hotelling and starts
MOVES3.0.1-
MOVES3.0.4
2021-2022
• Incorporated many small updates as detailed in the MOVES3
Update Log.
M0VES3.1
2022
• Added an l/M benefit for Class 2b and 3 gasoline trucks with a
gross vehicle weight rating between 8,500 and 14,000 pounds.
M0VES4J
2023
• Updates as explained in Section 2
J If updates are made to M0VES4, they will be documented in an update log available as a link from the MOVES4
page, https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves.
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1.3 MOVES Uses
MOVES is used by the U.S. EPA to estimate emission impacts of mobile source regulations and policies,
and to generate mobile sector information for national inventories of air pollutants such as the National
Emissions Inventory and the National Air Toxics Assessment.
U.S. state and local agencies outside of California use MOVES to develop emission inventories for a
variety of regulatory purposes, including the development of state implementation plans (SIPs),
transportation conformity determinations, general conformity determinations, and analyses required
under the National Environmental Policy Act (NEPA), among others.5 EPA provides training6 and
technical guidance on using MOVES for SIP and conformity modeling,7 PM hot-spot analyses,8 and CO
hot-spot analyses,9 including information on how to choose appropriate model inputs. MOVES is also
used for state and local greenhouse gas emission planning.10
Others, including academics and interest groups, may also use MOVES to model the effects of policy
choices and various mobile source scenarios.
When determining if MOVES is appropriate for a given use, modelers should be aware of both EPA
guidance5,710 and the limitations discussed in Section 8 below.
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2. Updates for M0VES4
Updates to MOVES4 are detailed in the MOVES4 technical reports for onroad. The most important
changes between MOVES3.1 and MOVES4 are summarized here. The only change made for nonroad
was a change to fuel properties.1
2.1 New Regulations
Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards
M0VES4 accounts for the Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and
Vehicle Standards, ("HD2027") published in January 2023.11 This rule sets tighter emission standards for
NOxand other pollutants from heavy-duty onroad vehicles starting in model year 2027.
Revised 2023 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions Standards
MOVES4 also accounts for the updated greenhouse gas standards for light-duty passenger cars and
trucks ("LDGHG 2023") published in December 2021.12 These standards set tighter carbon dioxide (C02)
limits for light-duty (LD) vehicles and are expected to lead to more electric vehicles (EVs) in the future
fleet.
Updated modeling of HDGHG2 rule
Due to a 2021 appeals court ruling vacating the portions of the heavy-duty greenhouse gas phase 2
standards (HDGHG2) that apply to trailers/3 we revised MOVES inputs that describe weight,
aerodynamics, rolling resistance and "other efficiency" improvements for combination trucks of model
year 2018 and later to better represent the implemented program. We also now hold constant the
"other efficiency" improvements for Class 2b and 3 vehicles in 2024 and beyond since we expect the
Phase 2 requirements for these vehicles to be met via electrification starting in MY2025. These changes
slightly increase the modeled emissions of C02 and other pollutants from these trucks.
2.2 New Features
Improved EV capabilities and EVfleet predictions
In MOVES4, we have updated the modeling of energy consumption by battery-powered light-duty
vehicles by improving our estimates of the energy used to move the vehicle14 and by explicitly
accounting for charging losses, battery efficiency, and energy use for cabin heating and cooling.15 Our
national average default forecast of future year light-duty BEV population is informed by a detailed
analysis of likely sales under the LDGHG 2023 standards and Inflation Reduction Act incentives.16
We also added the ability to model battery-powered heavy-duty vehicles,17 similarly accounting for
charging losses, battery efficiency, and energy use for cabin heating and cooling.15 Our national average
default forecast of future year heavy-duty BEV vehicle populations is informed by analysis of state
adoption of the California Advanced Clean Trucks rule.16
New ability to model HDfuel cell vehicles
In MOVES4, we have added the ability to model energy consumption and activity from hydrogen fuel
cell powered electric vehicles (FCEVs) for heavy-duty trucks. However, MOVES output combines FCEV
values with the values for BEVs, so generating FCEV-specific output requires either multiple runs or
results post-processing. MOVES does not model light-duty FCEVs. Our national average default forecast
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of future year heavy-duty FCEV population is informed by analysis of state adoption of the California
Advanced Clean Trucks rule.16
THQ NOx, and energy consumption adjusted to account for fleet averaging with EVs
Under the Tier 3 and LDGHG rules, manufacturers meet emission standards as an average across the
fleet and can use credits from electric vehicles to offset higher emissions from vehicles with internal
combustion engines (ICE). Thus, as future EV sales increase nationally, we expect average ICE emissions
and energy consumption will also increase.15 This is seen in higher per-vehicle emission rates for
MOVES4 gasoline and diesel light-duty vehicles.k The fleet averaging algorithm always uses the national
default EV sales fractions, regardless of what scale is selected in the RunSpec, because average, banking,
and trading (ABT) happens at the national level and not at the local level.
Added hotelling for EV and CNG long-haul combination trucks
As detailed in Section 3.3, hotelling activity in MOVES is defined only for long-haul combination trucks.
Previous MOVES versions modeled all long-haul combination trucks as diesel powered. MOVES4 can
also model battery electric, fuel-cell electric, and compressed natural gas (CNG) long-haul combination
trucks and can estimate the emissions and energy use associated with their hotelling. This now includes
energy use associated with shore (grid) powered hotelling operation.
2.3 Updates to Emission Rates
Updated ammonia rates
MOVES3 ammonia (NH3) emission rates were based on studies conducted in 2001 and earlier on a
limited number of vehicles. These lacked current emission aftertreatment technologies such as selective
catalytic reduction (SCR). The new MOVES4 rates are based on real-world measurements from more
than 300,000 light-duty vehicles and hundreds of heavy-duty trucks from model year 1965 -2018.
Compared to MOVES3, they show much higher ammonia emissions from both gasoline and diesel
vehicles.
Updated rates for nitrous oxide, nitrogen oxide, and nitrogen dioxide
The same studies used to update diesel ammonia rates were used to update MOVES estimates of the
greenhouse gas nitrous oxide (N20). This data was also used to update how total NOx Is allocated
between nitrogen oxide (NO) and nitrogen dioxide (N02). As a result, MOVES4 estimates of N20
emissions are much higher than in previous MOVES versions and, for a given quantity of NOx emissions,
MOVES4 estimates more NO and less N02.
For a more complete list of emission rate updates, see Table 2-1.
k Note, the rule also allows fleet averaging with electric vehicles for Regulatory Class 41 vehicles, but this is not
modeled in MOVES4.
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2.4 Updates to Fuel Characteristics, Vehicle Populations and Activity
Gasoline fuel properties have been updated using data from EPA fuel compliance submissions. We also
forecast gasoline parameter changes for Dallas area counties that will soon be required to use
reformulated gasoline (RFG).
Updates to national VMT and vehicle population inputs were based on newer historical data from the
Federal Highway Administration (FHWA) and updated forecasts from the Department of Energy.
Updates to national default fuel, regulatory class, and age distributions were based on newer vehicle
registration data, as well as the EV sales forecasts mentioned in Section 2.2.16
For a more complete list, see Table 2-1.
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Table 2-1: Algorithm and Data Updates for M0VES4 and Emission implications
Area
Description of Change and Emission Implications
Heavy-duty diesel emissions for
MY 2027 and later
Reduced emissions from heavy-duty diesel vehicles due to
HD2027 rule. In particular, there are notable reductions in
running, start and extended idle NOx. There are also reductions
in running PM2.5, THC, and CO and reductions in crankcase
emissions of all pollutants.
Heavy-duty gasoline emissions
for MY 2027 and later.
Slight reductions in NOx, THC, CO and PM25 emission rates for
running processes due to the HD2027 rule.
Heavy-duty energy consumption
for MY 2018 and later
Slight increases in energy consumption due to updated modeling
of HDGHG2 rule.
Light-duty gasoline PM emissions
for MY 2017 and later
Slight decreases in PM due to updated data and projections of
prevalence of gasoline direct injection engines.
Light-duty vehicle energy
consumption and NOx and THC
emissions for internal
combustion engine vehicles of
MY 2017 and later
Adjusted to account for manufacturer "averaging, banking and
trading" with electric vehicles. Compared to MOVES3, this
increases per-vehicle emissions from gasoline, diesel and E-85
light-duty vehicles.
Light heavy-duty diesel emissions
Reduced emission deterioration rates for THC, CO & NOx
emissions from light heavy-duty vehicles based on corrected
warranty period.
Heavy-duty diesel extended idle
elemental carbon (EC) and non-
EC emissions for MY 2007 and
earlier.
Corrected database for speciation of diesel extended idle PM25
emissions, increasing EC fraction of PM emissions and decreasing
non-EC fraction.
Light- and heavy-duty ammonia
emissions for gasoline vehicles of
MY 1981 and later, and diesel
vehicles of MY 1960 and later.
Increased NH3 emissions based on new data.
Heavy-duty diesel vehicle N20 for
MY 2004+
Increased N20 emissions based on new data.
Diesel vehicle N02 and NO for all
model years
Updated N02:NOx and NO:NOx ratios such that NO fraction
increases and N02 fraction decreases.
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Area
Description of Change and Emission Implications
Crankcase emissions for HD
diesel vehicles
Updated algorithm that calculates crankcase emissions by
regulatory class. Net emission impacts are small and vary by
pollutant.
Speciation for air quality
modeling
Removed chemical mechanisms and updated rocspeciation and
nrrocspeciation tables. No impact on total emissions of
hydrocarbons, NonHAPTOG, or any PM species.
Refueling vapor emissions from
gasoline and E-85 vehicles
New data and improved algorithm generally increase refueling
vapor emissions. HD gasoline vehicle refueling emissions decrease
in later years because of HD2027 rule requirements. We also
updated default information on the location of Stage II vapor
recovery programs.
l/M Coverage
Updated the default list of counties with l/M programs to account
for corrections, program changes, and program terminations.
Updated NOx humidity
adjustments
NOx emissions are slightly more sensitive to ambient humidity
due to improved algorithms for all fuel types.
Default national VMT, default
national vehicle populations, and
default vehicle age distributions
Updated historical data and forecasts.
Default vehicle fuel type and
regulatory class mix
Updated historical mix and forecasts. Moved engine-certified
Class 3 trucks from regulatory class 41 to 42 to better match
emissions. Reduced population of heavy-duty "glider" trucks.
Unlike MOVES3, MOVES4 includes non-zero EV fractions.
Relative Mileage Accumulation
Updated LD mileage accumulation based on DOT analysis of
odometer data from a random national sample of one million
light-duty vehicles. The new analysis shows that cars and light
trucks/SUVs are driven more similarly. It also shifts the
distribution of VMT from newer to older vehicles
U.S. Counties
Accounted for split in Alaska county equivalent by removing one
county and adding two more.
Gasoline properties
Updated gasoline properties for calendar years 2018 and later.
Fuel energy and carbon content
Updated fuel density, energy density, and carbon content for
diesel and gasoline fuels. Declines in energy density and
increased carbon content led to very small increases in C02 and
S02 emissions. We also updated the fuel densities used in
nonroad calculations.
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2.5 Updates to User Interface and User Inputs
The structure of MOVES4 is fundamentally the same as MOVES3, with some minor changes, including
changes in the MOVES graphical user interface (GUI), run specifications, input and output databases.
Since we have updated the source type and fuel type combinations available in MOVES4, RunSpecs
created with MOVES3 will be missing these combinations. If a fuel type is missing from a particular
source type, vehicle activity apportioned to that fuel type will not be accounted for in the emissions
estimates. Therefore, to prevent accidental "missing VMT", MOVES4 will automatically add all missing
fuel types associated with each selected source type in the RunSpec and provide a warning message.
Additionally, because we changed how MOVES models speciated emissions in MOVES3.0.4, RunSpecs
created with versions prior to MOVES3.0.4 that included chemical mechanisms will not work with
MOVES4. If you intend to use MOVES to generate speciated emissions for air quality modeling, you will
need to recreate your RunSpecs with MOVES4.
Changes to input databases mean that user input databases created for MOVES3 cannot be used with
MOVES4. MOVES4 includes a converter tool to assist this process. However, all existing CDBs and PDBs
will need to be manually updated to import the new default fuels data.
Additional information is also included in the MOVES4 technical guidance7 and the MOVES4 code
documentation at https://github.com/USEPA/EPA MOVES Model.
For nonroad runs, the only inputs that have changed since MOVES3.0.3 are related to speciation of
chemical mechanisms. Nonroad RunSpecs developed for M0VES3 should generally work with M0VES4
unless chemical mechanisms were selected for output.
The most important interface and user input changes are summarized in Table 2-2.
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Table 2-2: Changes in MOVES interface from M0VES3 to M0VES4
Description
Notes
RunSpec Selections
Added vehicle/fuel combinations
MOVES4 adds electricity as a fuel type for all heavy-duty
source types, as well as CNG for long-haul combination
trucks
Changed pollutant/process
combinations
MOVES4 does not model chemical mechanism species, but
adds NonHAPTOGMechanism as a selectable pollutant,
intended to be used with the Speciation Profile Scripts tool
Added option to skip domain
database validation
If selected, MOVES will skip the domain database validation
step, allowing the model to be run without getting a green
check on the Create Input Database Panel in the GUI. This
may be useful in advanced situations where domain
databases are split into separate databases. However, its use
is not recommended for most analyses as it can easily lead
to invalid results
User Input Tables
HotellingActivityDistribution
Added fuelTypelD column and changed the definition of
some of the hotelling operating modes
ZoneMonthHour
Added molWaterFraction column, removed temperatureCV
and relativeHumidityCV columns, and changed columns
temperature, relHumidity, heatlndex, and specificHumidity
to type DOUBLE
AVFT
MOVES4 Alternative Vehicle Fuels and Technologies (AVFT)
table includes more fuel types (see "Added vehicle/fuel
combinations" above.)
Changed Definitions
Regulatory Class 41 and 42
Engine-certified Class 3 trucks moved from regulatory class
41 to 42
Long-haul Combination Trucks
No longer required to be diesel only
Hotelling operating modes
opModelD 203 corresponds to hotelling shore power (plug
in) and opModelD 204 corresponds to hotelling battery or all
engines/accessories off
New Output
New rows and SCCs
There are new SCCs for heavy-duty electric vehicles and for
CNG long-haul combination trucks.
Translation tables
To aid in decoding MOVES output, MOVES4 output
databases include sixteen new tables that "translate"
MOVES numeric codes. These table names all start with
"translate." As such, the former "activitytype" is now named
"translate_activitytype".
18
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Description
Notes
Changes in GUl
Added information to Help menu
Changed process column name
With the addition of shore power as a hotelling operating
mode, the "Auxiliary Power Exhaust" process column on the
Pollutants and Processes Panel has been renamed "Other
Hotelling Exhaust". Note that this change does not have a
corresponding change in the RunSpec; MOVES will
automatically calculate shore power energy demand if
Auxiliary Power Exhaust is selected in the RunSpec
Added options to the Tools menu
MOVES4 contains tools to convert MOVES3 databases to
MOVES4, the AVFTTool, and Speciation Profile Scripts
Software Changes
Version updates
MOVES4 is distributed with updated versions of MariaDB,
Go, and Java
Command Line Changes
"MOVESMaster.bat" changed to
"MOVESMain.bat"
Important if you have automated your process for running
MOVES
Improved input database
validation
MOVES4 will execute all the input database validation steps
when running on the command line as it would when
running through the GUI, preventing a run that does not
have "all green checks" from starting.
Default Database Schema
Added new tables
• ActivityType
• EVEfficiency
• EvPoplCEAdjustLD
• NOxHumidityAdjust
• NRROCSpeciation
• RefuelingControlTechnology
• ROCSpeciation
Removed tables
• ExtendedldleHours
• LumpedSpeciesName
• TemperatureFactorExpression
• TOGSpeciation
• TOGSpeciationProfile
19
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Description
Notes
Changed schema for existing
tables
• atratio: fuelFormulationID is now type INT(ll)
• basefuel: fuelFormulationID is now type INT(ll)
• crankcaseemissionratio: added column regClassID
• criteriaratio: fuelFormulationID is now type INT(ll)
• emissionratebyagelev: polProcessID is now type
int(ll)
• emissionratebyagenlev: polProcessID is now type
int(ll)
• fueladjustment: fuelFormulationID is now type INT(ll)
• fuelformulation: fuelFormulationID is now type
INT(ll)
• fuelsupply: fuelFormulationID is now type INT(ll)
• fueltype: removed the humidityCorrectionCoeff and
humidityCorrectionCoeffCV columns
• generalfuelratio: fuelFormulationID is now type
INT(ll)
• hotellingactivitydistribution: added column fuelTypelD
• hotellinghours: added column fuelTypelD
• nrfuelsupply: fuelFormulationID is now type INT(ll)
• nrfueltype: removed the humidityCorrectionCoeff and
humidityCorrectionCoeffCV columns
• zonemonthhour: added molWaterFraction column,
removed temperatureCV and relativeHumidityCV
columns, and changed columns temperature,
relHumidity, heatlndex, and specificHumidity to type
DOUBLE
No Longer Available
Chemical mechanisms
• Like MOVES3.0.4 and MOVES3.1, MOVES4 does
not quantify chemical mechanism species for air
quality modeling. Instead, MOVES4 can estimate
emissions of aggregate residual organic gases and
particulate matter and provides a speciation table
that modelers can use to generate the
corresponding SPECATE profile during post-
processing.
20
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3. MOVES On road Algorithms
The way MOVES calculates emissions varies depending on the processes and pollutants being modeled,
and the vehicle or equipment type. This section provides a brief general overview of the algorithms used
to model emissions from cars, trucks and other onroad sources. The MOVES onroad technical reports,
available at https://www.epa.gov/moves/moves-onroad-technical-reports. provide detailed information
on algorithms and default inputs for all onroad source types and pollutant process combinations.
For all onroad processes, the emissions of detailed organic gas and PM species are calculated by
applying appropriate speciation factors.18
For electric vehicles, the only relevant processes in MOVES are brake wear and tire wear, as well as
running and hotelling (for energy consumption).
3.1 Running Exhaust and Energy
Running emissions are the archetypal mobile source emissions—exhaust emissions from a running
vehicle. "Running emissions" also covers energy consumption while running. Running operation is
defined as operation of internal-combustion engines after the engine and emission control systems have
stabilized at operating temperature, i.e., "hot-stabilized" operation.19
The general flow of information to calculate running emissions for onroad sources is summarized in
Figure 3-1, below. The model uses vehicle population information to sort the vehicle population into
source bins defined by vehicle source type, fuel type (gas, diesel, etc.), regulatory class, model year and
age. Regulatory classes define vehicles with similar emission standards, such as heavy heavy-duty
regulatory classes, which may occur in vehicles classified in several different source types, such as long-
haul combination, short-haul single-unit and refuse trucks.16
For each source bin, the model uses vehicle characteristics and activity data (vehicle miles traveled
(VMT), speed, idle fractions and driving cycles) to estimate the source hours in each running operating
mode. The running operating modes are defined by the vehicle's instantaneous vehicle speed,
acceleration and estimated vehicle power.201719
Each source bin and operating mode is associated with an emission rate, and these are multiplied by
source hours, adjusted as needed, and summed to estimate the total running emissions. Depending on
the pollutant and vehicle characteristics, MOVES may adjust the running emissions to account for local
fuel parameters,2 heating and air conditioning effects, ambient temperature, humidity, electrical
charging losses, fleet averaging, LD inspection and maintenance programs15 and fuel economy
adjustments.14
21
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Vehicle
Miles
Traveled
Average
¦
Driving
Speed
¦
Cycle
Source Hours
Operating
\
Emissions Test Data
Vehicle Activity
Vehicle Characteristics
Results
Operating Mode
Distribution
Emission Rates (g/hr)
Emissions
Adjustments:
Fuel Parameters
Temperature
Humidity
Air Conditioning
Etc.
Adjusted Emissions
Repeat & sum over
vehicles by model year,
regulatory class & fuel
type
Figure 3-1: Calculating Running Emissions for Onroad Vehicles
3.2 Start Exhaust
Onroad "start" emissions are the instantaneous exhaust emissions occur at the engine start (e.g., due to
the fuel rich conditions in the cylinder to initiate combustion) as well as the additional running exhaust
emissions that occur because the engine and emission control systems have not yet stabilized at the
running operating temperature. Operationally, start emissions are defined as the difference in emissions
between an exhaust emissions test with an ambient temperature start and the same test with the
engine and emission control systems already at operating temperature. As such, the units for start
emission rates are instantaneous grams/start.
The model uses vehicle population information to sort the vehicle population into source bins defined
by vehicle source type, fuel type (gas, diesel, etc.), regulatory class, model year and age. The model uses
default data from instrumented vehicles (or user-provided values) to estimate the number of starts for
each source bin and to allocate them among eight operating mode bins defined by the amount of time
parked ("soak time") prior to the start. Thus, the model accounts for different amounts of cooling of the
engine and emission control systems. Each source bin and operating mode has an associated g/start
emission rate. Start emissions are also adjusted to account for fuel characteristics, LD inspection and
maintenance programs, and ambient temperatures.17,19
3.3 Hotelling Emissions (Extended Idle Exhaust and Auxiliary Power Exhaust)
MOVES defines "hotelling" as any long period of time (e.g., > 1 hour) that drivers spend in their long-
haul combination truck vehicles (source type 62) during mandated rest times. Hotelling is differentiated
from off-network idling because the engines are often idling under load while hotelling (e.g., to maintain
cabin climate or run accessories).
22
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The default MOVES hotelling hours are computed as a fixed ratio to the miles these trucks travel on
restricted access roads.16
In MOVES4, the hotelling algorithm was updated to cover CNG and electric vehicles and to revise the
available operating modes. In MOVES4, hotelling activity is allocated among four operating modes:
engine idle ("extended idle"), diesel auxiliary power unit (APU) use, "Shore Power/' i.e., plugged-in, and
"Battery or All Engines and Accessories Off." This allocation varies by model year and fuel type.16
MOVES computes emissions for extended idle and APU use based on the hours and source-bin specific
emission rates. Hotelling NOx emissions are adjusted for ambient humidity. In MOVES output, extended
idle, APU, and shore power are assigned separate emission processes.17
3.4 Crankcase (Running, Start & Extended Idle)
Crankcase emissions include combustion products that pass by the piston rings of a compression ignition
engine as well as oil droplets from the engine components and engine crankcase that are vented to the
atmosphere.21
In MOVES, onroad crankcase emissions are computed as a ratio to the exhaust emissions, with separate
values for running, start and hotelling (extended idle mode only). The crankcase ratio varies by
pollutant, sourcetype, regulatory class, fuel type, model year and exhaust process.17
3.5 Brake Wear
Brake pads lose material during braking. A portion of this lost material becomes airborne particulate
matter. This "brake wear" differs from exhaust PM in its size and chemical composition.
MOVES estimates brake wear from onroad vehicles using weighted average g/hour rates that consider
brake pad composition, number and type of brakes and braking intensity. The emission rates in MOVES
vary by vehicle regulatory class to account for average vehicle weight. They are the same for electric and
conventional vehicles. Braking activity is modeled as a portion of running activity. In MOVES, the running
operating modes for braking, idling and coasting are all modeled as including some amount of braking.
The operating mode "brakewear; stopped" can be used at the project scale to model emissions of an
idling vehicle with no braking.22
3.6 Tire Wear
Contact between tires and the road surface causes tires to wear, and a portion of this material becomes
airborne. This "tire wear" differs from exhaust PM in its size and chemical composition.
MOVES tire wear rates in g/hr are based on analysis of LD tire wear rates as a function of vehicle speed,
extrapolated to other vehicles based on the number and size of tires. The analysis also considers the
fraction of tire wear that becomes airborne. The tire wear operating mode bins differ from those used
for running emissions and brake wear because they account only for speed and not for acceleration.22
3.7 Evaporative Permeation
Permeation is the migration of hydrocarbons through materials in the fuel system. Permeation
emissions are strongly influenced by the materials used for fuel tank walls, hoses, and seals, and by the
temperature, vapor pressure and ethanol content of the fuel.
23
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In MOVES, permeation is estimated only for vehicles using gasoline-based fuels (including E-85).
Permeation is estimated for every hour of the day, regardless of activity. Permeation rates in g/hour
vary by model year to account for the phase-in of tighter standards. Permeation emissions are adjusted
to account for gasoline fuel properties and ambient temperatures.23
3.8 Evaporative Fuel Vapor Venting
When gasoline fuel tank temperatures rise due to vehicle operation or increased ambient temperatures,
hydrocarbon vapors are generated within the fuel tank. The escape of these vapors is called Tank Vapor
Venting (TVV) or Evaporative Fuel Vapor Venting. This vapor venting may be eliminated with a fully
sealed metal fuel tank. More commonly, venting is reduced by using an activated charcoal canister to
adsorb the vapors as they are generated; vapors from the canister are later consumed during vehicle
operation. However, to prevent pressure build-up, canisters are open to the atmosphere, and after
several days without operating, fuel vapors can diffuse through the charcoal or pass freely through a
completely saturated canister. Tampering, mal-maintenance, vapor leaks and system failure can also
result in excess vapor venting.
MOVES calculates vapor venting only for vehicles using gasoline-based fuels (including E-85). The tank
vapor generated depends on the rise in fuel tank temperature, fuel vapor pressure, ethanol content and
altitude. Fuel tank temperature changes are modeled as a function of 24-hour temperature patterns and
default vehicle activity, with different vapor generation rates for vehicles that are operating, "hot
soaking" (parked, but still warm) and "cold soaking" (parked at ambient temperature). MOVES4
evaporative emission calculations have not been updated for off-network idle and thus model this idle
time as hours parked. Vapor venting is modeled as a function of vapor generated, days cold soaking,
model-year specific vehicle fuel system characteristics, and age and model year related vapor leak rates,
inspection and maintenance (l/M) programs can also impact leak prevalence rates.23
3.9 Evaporative Fuel Leaks (Liquid Leaks)
Liquid leaks are fuels escaping the gasoline fuel system in a non-vapor form. In MOVES, they are referred
to as evaporative fuel leaks because they subsequently evaporate into the atmosphere after escaping
the vehicle. These leaks may occur due to failures with fuel system materials, or due to tampering or
mal-maintenance. Liquid spillage during refueling is modeled separately as part of the refueling process.
In MOVES, fuel leak frequency is estimated as a function of vehicle age and vehicle emission standards.
Fuel leak size (g/hour) is a function of age and vehicle operating mode (cold soaking, hot soaking or
operating).23
3.10 Refueling Displacement Vapor and Spillage Loss
Refueling emissions are the displaced fuel vapors when liquid fuel is added to the vehicle tank. Refueling
spillage is the vapor emissions from any liquid fuel that is spilled during refueling and subsequently
evaporates. Diesel vehicles are assumed to have negligible vapor displacement, but MOVES does
compute emissions for onroad diesel fuel spillage.
Refueling vapor and spillage emissions are estimated from the total volume of fuel dispensed (gallons).
This volume is based on previously calculated fuel consumption. In addition, refueling emissions are a
function of gasoline vapor pressure, ambient temperatures, the presence of an on-board refueling vapor
24
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recovery system (ORVR) on the vehicles, and the use of Stage II vapor recovery controls at the refueling
pump. The effectiveness of ORVR systems decline with age.23
25
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4. MOVES Nonroad Algorithms
This section provides a brief general overview of the algorithms used to model emissions from nonroad
equipment types. These calculations vary depending on the processes and pollutants being modeled and
the equipment type. They also depend on whether the equipment uses a spark-ignition (SI) or
compression-ignition (CI) engine, and the engine horsepower (hp) size class. The MOVES nonroad
technical reports at https://www.epa.gov/moves/nonroad-technical-reports provide detailed
information on algorithms and inputs for the nonroad calculations.
The MOVES nonroad module estimates emissions as the product of an adjusted emission factor
multiplied by rated power, load factor, engine population and activity. Starting with base-year
equipment populations by technology type and model year, the model uses growth factors to estimate
the population in the analysis year. Estimates of median life at full load, load factors, activity and age
distributions are then combined to generate estimates of nonroad emissions by equipment type, fuel
type and age. Equipment populations are also allocated to county and season; national equipment
populations are allocated to the county level using surrogate data.
The nonroad module has importers for user information on meteorology and fuels, and a "generic"
importer that can be used to enter data on retrofit programs. We recommend accounting for custom
population and activity using post-processing scripts as explained in the training and technical guidance.
For all nonroad processes, toxics are estimated in the nonroad portion of the model, but detailed TOG
speciation and speciation of PM2.5 must be post-processed.24
4.1 Running Exhaust
For nonroad, "running exhaust" emissions include exhaust emissions both at start and during running
operation.
The MOVES nonroad module calculates an emission factor for THC, CO, N0X, PM and brake-specific fuel
consumption (BSFC) as the product of a steady-state emission factor for new ("zero-hour") engines, a
transient adjustment factor if needed to represent typical operation, and a deterioration factor to
account for wear and aging. Gasoline THC, CO and N0X emissions are adjusted to account for gasoline
oxygenate content. S02 emissions from all nonroad equipment is a function of BSFC and fuel sulfur level.
Diesel PM emissions are adjusted to account for diesel fuel sulfur levels.25 Temperature effects are
applied to THC, CO and N0X exhaust emissions from 4-stroke SI engines.26
4.2 Crankcase Exhaust
Crankcase emissions are those emissions that escape from the combustion chamber past the piston
rings into the crankcase and out to the atmosphere.
The MOVES nonroad module models THC crankcase emissions for four-stroke spark-ignition engines
that have open crankcases27 and for all compression-ignition engines prior to implementation of the Tier
4 NR diesel standard.28
26
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4.3 Refueling Displacement Vapor and Spillage Loss
Refueling emissions are the displaced fuel vapors when liquid fuel is added to the equipment fuel tank.
Refueling spillage is the vapor emissions from any liquid fuel that is spilled during refueling and
subsequently evaporates.29
For both spillage and vapor displacement, the MOVES nonroad module initially calculates an THC
emission factor in terms of grams of emissions per gallon of gasoline fuel consumed. Fuel consumption
is then used to calculate total emissions. The g/gal emission factor varies as a function of fuel tank
volume, gasoline RVP, ambient and dispensed fuel temperatures, and whether the equipment is more
likely fueled using a portable container or at the pump, and the use of Stage II vapor recovery controls at
the refueling pump.
No refueling emissions are reported for diesel, CNG or LPG nonroad equipment.
4.4 Fuel Vapor Venting (Diurnal, HotSoak and Running Loss)
Fuel vapor venting emissions for nonroad equipment are analogous to the evaporative vapor venting
emissions for onroad vehicles. Diurnal emissions are vapors generated due to temperature changes
throughout the day; running emissions are generated by heating caused by engine operation, and hot
soak emissions are generated from residual heat from the equipment just after the engine is shut off.
In general, diurnal emissions are calculated based on equipment standards, percent tank fill, percent
headspace, tank size, vapor pressure of the fuel and the minimum and maximum ambient temperature.
Diurnal emissions for recreational marine emissions are calculated slightly differently. Running loss
emissions are calculated as a function of operating time and are not affected by ambient temperatures.
Hot soak emissions are a function of default equipment starts/hour and gram/start rates.
No fuel vapor venting emissions are reported for diesel, CNG or LPG nonroad equipment.30
4.5 Permeation: Tank, Hose, Neck, Supply/Return and Vent Hose
Permeation is the migration of hydrocarbons through materials in the fuel system. Permeation
emissions are strongly influenced by the materials used for fuel tank walls, hoses and seals—and are
also affected by the temperature, vapor pressure and ethanol content of the fuel.
The MOVES nonroad module calculates various types of permeation. No permeation is calculated for
spark-ignition engines larger than 25 hp because they usually have impermeable metal fuel tanks and
lines.
Fuel tank permeation is calculated as the product of the inside area of the fuel tank, a tank permeation
emission factor that varies with equipment emission standard and a temperature adjustment. The
permeation is also adjusted to account for the market share of ethanol blend gasolines.
Fuel hose permeation is calculated as the product of the surface area of non-metal hoses, a hose
permeation emission factor that varies with equipment size category and emission standard, and a
temperature adjustment. For recreational marine equipment, separate fuel hose emissions are
calculated for the supply/return, fill neck, and vent lines.
No permeation emissions are reported for diesel, CNG or LPG nonroad equipment.30
27
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5. M OVES Softwa re Structu re
MOVES is written in Java (compiled with Microsoft's build of OpenJDK), MariaDB, and the Go
programming language. The Nonroad model component is written in Fortran. The principal user inputs,
outputs and most of the model's internal working storage are held in MariaDB databases. The model
includes a default database with emission rates, adjustment factors, and relevant information for all U.S.
counties that supports model runs for calendar years 1990 and 1999-2060.
The MOVES architecture was originally designed to model only onroad vehicles. In 2014, the existing
NONROAD2008 model was integrated into MOVES as the "MOVES nonroad module". The nonroad
module uses the same interface as the rest of MOVES, but the calculations are handled by a separate
Fortran program.
MOVES uses a main process/worker-process program architecture that enables multiple computers to
work together on a single model run. However, a single computer can be used to execute MOVES runs
by running both the main and worker components on the same computer.
The following diagram illustrates the overall flow of processing in MOVES highlighting the division of
work between the MOVES Main and Worker programs.
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Figure 5-1- Diagram of MOVES information flow
5,1 MOVES Software Components
Looking at this architecture in greater detail, the MOVES software application consists of several
components, introduced briefly in this chapter. More information is available in the documentation at
the MOVES GitHub site, https://github.com/USEPA/EPA MOVES Model/tree/master/docs.
MOVES Graphical User Interface (GUI)
The MOVES GUI is a Java program that may be used to create, save, load, and modify a run specification
or "RunSpec", and to initiate and monitor the status of a model run. The MOVES GUI also includes data
managers that assist users in building the input databases required for county and project scale runs and
includes error-checking code to ensure that the RunSpec and inputs are consistent with MOVES
algorithms and capabilities.
29
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MOVES Main Program
When the run is started, MOVES Main uses information in the RunSpec, the default database, and the
user input domain database to generate the execution database specific to the MOVES run. This is done
using "Generator" modules. The Main program then bundles data and calculation instructions into ToDo
files to be processed by MOVES Workers. The MOVES Main also compiles the results returned from the
MOVES Workers via Done files into the MOVES output database and performs final aggregation steps.
During the MOVES run, both the ToDo and Done files are stored in the SharedWork directory which
must be accessible to both the Main and Worker programs.
Note that only one executing MOVES Main program can be used during a MOVES run.
MOVES Worker Program
The MOVES Worker program processes the ToDo files created by the MOVES Main program and returns
the results as Done files. This processing is done by various "Calculator" modules.
At least one executing copy of this program is needed to complete a MOVES run. Running multiple
MOVES Worker programs during a MOVES run enables ToDo files to be processed in parallel. While this
capability may reduce the duration of a MOVES run, the improvement in performance strongly depends
on the contents of the RunSpec and the computing environment. The MOVES Worker program may be
executed on the same computer as the MOVES Main program, or on other computer(s) having access to
the SharedWork file directory.
MOVES Nonroad Code
The code used to model nonroad emissions in MOVES predates the MOVES model. Beginning with
MOVES2014, the standalone NONROAD model was incorporated into MOVES such that the NONROAD
Fortran program is called by the MOVES Worker program. MOVES supplies the Fortran program with the
appropriate flat file inputs based on values from the MOVES default database and any optional user
input databases. Note that nonroad and onroad share the same default meteorology and fuel inputs.
After the MOVES Worker executes the NONROAD Fortran program, it post-processes the Fortran output
flat files and saves the results in the MOVES output database.
Later minor releases of MOVES2014 improved population growth estimates and diesel emission factors,
in addition to new features including Go-based calculators that compute nonroad fuel subtype splits,
some nonroad THC species, and nonroad air toxics.
5.2 MOVES Databases
The MOVES model stores and accesses data for its calculations in a series of MariaDB databases. This
section introduces the different types of MOVES databases, and how they are used by the program. A
detailed description of each MOVES input and output table is available at MOVES Database Tables.
Default Database
The default database is included in the MOVES Installation Package and is required for MOVES to run.
This database contains the required emission factors, adjustment factors, fuel data, and default vehicle
population and activity data for all U.S. counties to support model runs for calendar years 1990 and
1999-2060.
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User Input Databases
User databases may contain any of the tables that are in the default input database and are used to add
or replace records as input by the user; EPA's MOVES Technical Guidance7 describes which data inputs
must be updated by the user for SIP and conformity purposes. These databases typically contain region-
specific fuels, vehicle populations, age distributions, activity, and where applicable, l/M program
characteristics. These databases are optional for a default run, but user input is required for runs at the
County or Project Scale. The MOVES GUI includes a County Data Manager and a Project Data Manager
that assist the user in creating an input database that contains all of the necessary data for a MOVES
run.
The MOVESExecution Database
This database is created by the MOVES Main program. It is used for temporary working storage during
the MOVES run. Users typically do not interact with this database; however, it may be saved for
troubleshooting purposes.
MOVES Output Databases
These databases are the final outputs of MOVES runs. The output database name is specified by the user
in the RunSpec. Output for Emission Inventory mode runs is contained in the movesOutput table.
Emission Rates mode produces output in multiple tables.
The output databases also include tables that describe each run in the output, activity data, translation
tables for the codes used in the output, information on errors during the run, and other tables used for
diagnostics and troubleshooting.
MOVESWorker Database
This temporary database is used as working storage by the MOVES Worker Program. When running with
multiple MOVES Workers, each Worker program creates its own MOVESWorker database. The user does
not interact directly with this database.
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6. MOVES4.0 Results
Vehicle and equipment emissions vary by location and time. This section shows MOVES4 results for the
United States as a whole, based on national defaults. For brevity, the graphs here show only a few of the
pollutants calculated by MOVES and are aggregated by fuel type and calendar year.
However, for the most accurate results for a given time and location, it is important to run MOVES for
the specific case using accurate local inputs. In contrast, the national results shared in this document are
calculated based on average inputs that do not fully capture the variation in emissions from time to time
and place to place. For selected pollutants, we also show onroad results for two sample urban counties
as modeled at County Scale with county-specific inputs. While the two counties shown here differ in
their traffic mix, fuels, and meteorology, they are not intended to represent the full range of local
trends. To understand mobile source emissions in a particular county, one must model that county.
These caveats are also true for the average emission rates EPA has provided to the Bureau of
Transportation Statistics (https://www.bts.gov/content/estimated-national-average-vehicle-emissions-
rates-vehicle-vehicle-type-using-gasoline-and).
Additional emission summaries for selected past years are available from the National Emissions
Inventory (https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei). The NEI
emissions are calculated with county-level inputs; NEI mobile source inventories through 2020 were
generated with previous versions of MOVES and thus lack M0VES4 updates.
6.1 Onroad
The following plots summarize key results for onroad vehicles from running M0VES4 at the national,
annual level using default inputs as compared to runs using the previous model, M0VES3.11. Because
results for specific times and locations will vary, for some pollutants, we also show results for two
sample urban counties with county-specific fleet, fuel, and meteorological conditions.
Note that, compared to M0VES3, M0VES4 generally predicts higher national emissions in 2017. This
reflects a shift in the default vehicle mix for historic years, including an older vehicle population. The
impact of this shift varies by pollutant.
Figure 6-1 shows a shift to electric vehicles in M0VES4 and a very slight decrease in projections of total
vehicle miles travelled.
1 M0VES3.1 emissions are very similar to those in previous versions of M0VES3. See Table 1-2.
32
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~
Gasoline H Diesel | Electricity
w
_0)
E 4
4—
o
»3-
o
12
Si-
>
5 0
o
H
Figure 6-1—National onroad vehicle miles travelled (VMT) in M0VES4 as compared to M0VES3.1. Percentage values indicate
change between M0VES3.1 and M0VES4.
For county level runs, modelers must enter county-specific VMT and fuel mix. Figure 6-2 illustrates VMT
for two example counties. County A includes future year electric vehicle population fractions that are
proportional to the county's historic share of national EVs. In contrast, County B includes future year
electric vehicle population fractions that reflect adoption of California's Advanced Clean Car (2012) and
Advanced Clean Trucks (2020) rules requiring electric vehicle sales for light- and heavy-duty vehicles. In
these county runs, the MOVES3 and MOVES4 inputs are the same for light-duty vehicles, but the
MOVES4 inputs also include HD EVs. The values shown here are used as inputs in the sample county
illustrations below.
2017
2035
2050
-1 %
-1.9 %
0 %
MOVES3.1
MOVES4
MOVES3.1
MOVES4
MOVES3.1
MOVES4
33
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County Scale Input VMT by Fuel Type
County A
County Scale Input VMT by Fuel Type
County B
Figure 6-2—Sample county-specific onroad vehicle miles travelled (VMT) in MOVES3 and MOVES4. Percentage values indicate
change compared to calendar year 2021. The values shown here are used in the sample county illustrations below.
Greenhouse Gases
While VMT is quite similar in both models, for exhaust C02 (Figure 6-3), M0VES4 projects greater
decreases over time than M0VES3. This reflects both changes in fleet mix and activity, and the phase-in
of the Revised Light Duty GHG Standards for 2023 and Later.
34
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2017
1.9 %
2035
-9.1 %
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MOVES3.1
MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
Figure 6-3—National onroad carbon dioxide in MOVES4 as compared to MOVES3.1. Percentage values indicate change between
MOVES3.1 and MOVES4.
As shown in Figure 6-4, MOVES4 predicts declining methane emissions from onroad vehicles. The
change between model versions reflects a shift in the default vehicle population from CNG vehicles,
which have high methane emissions, to electric vehicles, which have none.
~ Gasoline ~ Diesel O CNG
tO
c
~ 150
0
to
100
re
to
1 50
¦4—»
5 o
2017
7.5 %
2035
CO
1
2 %
2050
-40.2 %
MOVES3.1
MOVES4
MOVES3.1
MOVES4
MOVES3.1
MOVES4
Figure 6-4—National onroad methane in MOVES4 as compared to MOVES3.1. Percentage values indicate change between
MOVES3.1 and MOVES4.
As shown in Figure 6-5, MOVES4 nitrous oxide emissions are significantly higher than MOVES3. This
reflects the incorporation of new real-world data for diesel vehicles.
35
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n Gasoline ~ Diesel ¦ CNG
w
c
o
75
(A
c 50
ro
w
125
O
™ 0
2017
116.4 %
2035
331.9 %
2050
316 %
MOVES3.1 MOVES4
MOVES3.1
MOVES4
MOVES3.1
MOVES4
Figure 6-5—National onroad N2Oin MOVES4 as compared to MOVES3. Percentage values indicate change between MOVES3.1
and MOVES4.
The net C02 equivalent emissions based on the emissions of C02, CH4 and N20 as weighted by their
global warming potentials are shown in Figure 6-6. The MOVES4 increase in N20 is outweighed by
decreases in C02 and CH4.
~ Gasoline ~ Diesel
(a
c
o
c 2.0
15
w 1 ^
I1.0H
d-0.5
O)
CN
°0.0
2017
2.5 %
2035
-8 %
2050
-16.9 %
MOVES3.1
MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
Figure 6-6—National onroad C02 equivalent in MOVES4 as compared to MOVES3. Percentage values indicate change between
MOVES3.1 and MOVES4.
Criteria Pollutants and Precursors
Figure 6-7 shows national NOx emissions decline overtime with the phase-in of light-duty and heavy-
duty rules in MOVES3 and MOVES4. MOVES4 shows additional declines primarily due to significantly
reduced heavy-duty diesel emissions with the phase-in of the Heavy-Duty NOx Rule for 2027 and Later,
36
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as well as the growing share of electric vehicles. As noted above, the higher emissions for 2017 are due
to a change in the default fleet mix.
«4
c
o
£3"
to
I2"
Ii-
X
O
20-
Figure 6-7—National onroad NOx in MOVES4 as compared to MOVES3. Percentage values indicate change between MOVES3.1
and MOVES4.
Figure 6-8 illustrates NOx for two example counties with the VMT shown in Figure 6-2 County A includes
future year electric vehicle population fractions that are proportional to the county's historic share of
national EVs. In contrast, County B includes future year electric vehicle population fractions that reflect
adoption of California's Advanced Clean Car (2012) and Advanced Clean Truck (2020) rules requiring
electric vehicle sales for light- and heavy-duty vehicles. In these county runs, the MOVES3 and MOVES4
inputs are the same for light-duty vehicles, but the MOVES4 inputs also include HD EVs. The declining
gasoline emissions in MOVES3 reflect the Tier 3 standards for gasoline vehicles and a shift from gasoline
to electric vehicles. The additional diesel reductions in MOVES4 demonstrate the effect of the Heavy-
Duty NOx Rule for 2027 and Later, a reduction in the number of gliders, and a shift of the heavy-duty
vehicle population from diesel to battery and fuel cell electric vehicles.
~ Gasoline ~ Diesel
2017
12.4 %
2035
-40.
0s
00
2050
cci
Lfi
l
9 %
MOVES3.1 MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
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NOx by Fuel Type
County A
10,000-
(/)
D
5,000 -
Fuel Type
| Gas
| Diesel
| CNG
E-85
EV
NOx by Fuel Type
County B
2021
4,000-
(/>
=>
-56.9%
-56.9%
> UJ
o >
s o
> ID
o >
s o
Fuel Type
| Gas
| Diesel
| CNG
J E-85
EV
Figure 6-8—Onroad NOxfrom two sample urban counties in MOVES4 as compared to MOVES3.1. Percentage values indicate
change compared to 2021.
Figure 6-9 shows national PM2.5 inventory declining with the phase-in of light-duty and heavy-duty PM
regulations. Compared to MOVES3, MOVES4 results in less PM exhaust primarily due to a reduction in
the number of glider vehicles and shifts to electric vehicles.
The graph also shows that brake and tire wear emissions are similar in MOVES3 and MOVES4. MOVES
uses the same brake and tire wear rates for all fuel types, and in both versions of MOVES brake and tire
wear form an increasing fraction of total onroad direct PM2.5 emissions.
38
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¦
Gasoline
¦
Diesel
~
Brakewear
~
Tirewear
c/>
= 125
S 100
75
50
25
0
w
¦D
C
re
w
in
c\i
2017
12.1 %
2035
-16.3 %
2050
-22.
6 %
MOVES3.1
MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
Figure 6-9—National PM2.sin MOVES4 as compared to MOVES3.1. Percentage values indicate change between MOVES3.1 and
MOVES4.
The PM trend observed in select urban counties in Figure 6-10 depicts total PM2.5 emissions by fuel type.
The gasoline and diesel emissions include exhaust, brake and tire wear. The electric emissions are from
brake and tire wear only. The results are similar to the national PM trend and illustrate both the
reduced emissions from diesel vehicles and the growing importance of brake and tire emissions.
39
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Total PM2.5 by Fuel Type
County A
Figure 6-lO—Onroad PM from two sample urban counties in MOVES4 as compared to MOVES3.1. The graph includes exhaust
PM as well as brake and tire wear. Percentage values indicate change compared to calendar year 2021.
Onroad VOC emissions are dominated by emissions from gasoline vehicles, which decline with the
phase-in of Tier 3 standards in both MOVES3 and MOVES4, and the increased fraction of electric
vehicles in the MOVES4 national results (Figure 6-11). As illustrated in Figure 6-12, evaporative
emissions are a growing fraction of future onroad VOC, especially emissions from vapor venting and
liquid fuel leaks.
40
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The VOC trend observed in select urban counties as shown in Figure 6-13 highlight near-term increases
in VOC. Figure 6-14 illustrates that these county-scale increases are primarily due to MOVES4 changes in
refueling emissions.
] Gasoline ~ Diesel
c
o
c 1.5
£ 1.0
o
w
c
0
1 0.5
o
o
>0.0
2017
10.6 %
2035
-0.5 %
2050
-12.
1 %
MOVES3.1
MOVES4
MOVES3.1
MOVES4
MOVES3.1 MOVES4
Figure 6-11—National onroad VOC in MOVES4 as compared to MOVES3.1. Percentage values indicate change between
MOVES3.1 and MOVES4.
D Vapor Venting O Fuel Leaks ~ Other H Running
D Permeation ~ Refueling ~ Starts
c/)
c
o
4-
o
(/>
c
o
1.0
2017
2035
I0'5
o
§ 0.0
MOVES3.1 MOVES4 MOVES3.1 MOVES4 MOVES3.1 MOVES4
Figure 6-12—National onroad VOC from gasoline vehicles by emission process in MOVES4 as compared to MOVES3.1.
2050
41
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VOC by Fuel Type
County A
4,000-
co
=)
Fuel
Type
¦
Gas
Diesel
¦
CNG
E-85
VOC by Fuel Type
County B
Figure 6-13—Onroad VOC by fuel type from two sample urban counties in MOVES4 as compared to MOVES3.1. Percentage
values indicate change compared to calendar year 2021.
42
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VOC by Process
County A
H
co
=)
-26.2%
-25.7%
¦
¦
-40.3%
-41.1%
u
¦
n
-50.1%-52.6
¦¦
-53.4%_57i5o/o
-54.5%
-59.9%
Process
Running Exhaust
Crankcase Running Exhaust
Start Exhaust
| Crankcase Start Exhaust
Evap Permeation
Evap Fuel Vapor Venting
| Evap Fuel Leaks
Refueling Displacement Vapor Loss
| Refueling Spillage Loss
Extended Idle Exhaust
Crankcase Extended Idle Exhaust
I Auxiliary Power Exhaust
VOC by Process
County B
2,000-
(/)
=)
-50.8%
-52.0%
1
_
-56.0%
-58.4%
¦
¦
-59.1%
-62.3%
¦
¦
Process
Running Exhaust
Crankcase Running Exhaust
Start Exhaust
Crankcase Start Exhaust
Evap Permeation
Evap Fuel Vapor Venting
Evap Fuel Leaks
Refueling Displacement Vapor Loss
Refueling Spillage Loss
Extended Idle Exhaust
Crankcase Extended Idle Exhaust
Auxiliary Power Exhaust
Figure 6-14—Onroad VOC by process from two sample urban counties in MOVES4 as compared to MOVES3.1. Percentage values
indicate change compared to calendar year 2021.
Like VOC, onroad CO emissions are heavily dominated by emissions from gasoline vehicles. The CO
emissions decline over time with the phase-in of Tier 3 standards and improved technology. MOVES4
changes compared to MOVES3 in Figure 6-15 are primarily due to changes in the vehicle fleet mix, as
well as declines in diesel CO with the HD2027 regulations. Figure 6-16 shows similar trends in sample
urban counties.
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n Gasoline ¦ Diesel
2035
-10 %
2050
-28.6 %
MOVES3.1
MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
Figure 6-15—National onroad CO in MOVES4 as compared to MOVES3.1. Percentage values indicate change between
MOVES3.1 and MOVES4.
44
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CO by Fuel Type
County A
Figure 6-16—Onroad CO from two sample urban counties in MOVES4 as compared to MOVES3.1. Percentage values indicate
change compared to calendar year 2021.
Figure 6-17 and Figure 6-18 show notable increases to the onroad ammonia inventory at the national
and county level. The change reflects the updated ammonia emission rates for gasoline and diesel
vehicles in MOVES4 to incorporate new data.
45
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~ Gasoline ¦ Diesel
2017
120.4 %
2035
33.7 %
2050
0°
%
MOVES3.1 MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
Figure 6-17—National onroad NH3in MOVES4 as compared to MOVES3.1. Percentage values indicate change between
MOVES3.1 and MOVES4.
46
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NH3 by Fuel Type
County A
H
co
=)
NH3 by Fuel Type
County B
c/)
Z)
Fuel Type
Figure 6-18—Onrood NH3from two sample urban counties in MOVES4 as compared to MOVES3.1. Percentage values indicate
change compared to calendar year 2021.
As illustrated in Figure 6-19 arid Figure 6-20, for future years, MOVES4 estimates lower S02 emissions as
compared to MOVES3. This reflects MOVES4 updates to gasoline sulfur content as well as lower
estimated gasoline consumption.
47
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~
Gasoline
¦
Diesel
2017
2.2 %
MOVES3.1
MOVES4
2035
-25.
4 %
MOVES3.1 MOVES4
2050
-32.2 %
MOVES3.1 MOVES4
Figure 6-19—National onroad S02 in MOVES4 as compared to MOVES3.1. Percentage values indicate change between
MOVES3.1 and MOVES4.
48
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S02 by Fuel Type
County A
S02 by Fuel Type
County B
Fuel
Type
¦
Gas
Diesel
¦
CNG
E-85
Figure 6-20—Onroad S02from two sample urban counties in MOVES4 as compared to MOVES3.1. Percentage values indicate
change compared to calendar year 2021.
6.2 Nonroad
The only nonroad input that was changed for MOVE4 was the sulfur level of nonroad gasoline fuel,
resulting in decreases in S02 as show in Figure 6-21.
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Gasoline
Nonroad Diesel
CNG
LPG
Marine Diesel
MOVES3.1 MOVES4
MOVES3.1 MOVES4
MOVES3.1 MOVES4
Figure 6-21 NonroadS02in MOVES4 as compared to MOVES3.1. Percentage values indicate change between MOVES3.1 and
MOVES4.
Emissions of other nonroad pollutants are the same in MOVES4 as in MOVES3. Figure 6-22 summarizes
annual nonroad emissions for key pollutants from running MOVES4 at the national level using default
inputs. Because nonroad activity varies substantially with season and geography, results for specific
times and locations will differ from these national results. As noted previously, MOVES does not cover
aircraft, locomotives, and commercial marine vessels.
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Gasoline Nonroad Diesel 1 CNG fl LPG Marine Diesel
3e+08
2e+08
1e+08
0e+00
-^-1000000
c
o
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7. MOVES Testing and Evaluation
To ensure that the MOVES model contains the state-of-the-science when estimating emissions from
mobile sources, and is usable by a variety of modelers, MOVES is subject to review and evaluation in
several different ways. Because the MOVES model is developed incrementally, review and evaluation of
earlier versions of MOVES is often relevant even for later versions.
7.1 Peer Review
Since MOVES2014b, we have conducted four rounds of peer review for the updates to MOVES3 and
MOVES4 data and algorithms, following EPA's peer review policies and procedures.31 Reviewer
comments and EPA's responses are documented online at https://cfpub.epa.gov/si/index.cfm with the
Record IDs listed below.
• In 2017, we conducted peer review of updates to onroad vehicle population and activity, heavy-
duty exhaust emission rates, fuel supply defaults, speciation and toxic emissions from on-road
vehicles, and particulate matter emissions from light-duty gasoline vehicles. (Record IDs 328810
and 328830)
• In 2019, we conducted a peer review of additional updates to the modeling of heavy-duty
vehicles, including updates to heavy-duty exhaust emission rates, incorporation of glider trucks
to MOVES, and updated start, hotelling and idling activity data from instrumented vehicle
studies. (Record IDs 347135 and 347136)
• In 2020, we conducted peer review of updates to the light-duty exhaust emission rates, updates
to heavy-duty crankcase emission rates, and updated fuel supply and fuel wizard factors.
(Record ID 347138)
• In 2022 and 2023, we conducted peer review of updates to the modeling of electric vehicles and
updates to refueling and ammonia emissions. (Record IDs 356887 and 356914)
Peer review documents for previous versions of MOVES are also available at this location.
7.2 MOVES Review Work Group
To provide expert feedback and advice on development of the first three versions of MOVES, the Mobile
Sources Technical Review Subcommittee (MSTRS) chartered a series of MOVES Review Work Groups
focused on sharing technical expertise. Members of the work group represent a variety of stakeholders,
including vehicle and engine manufacturers, fuel producers, state and local emission modelers,
academic researchers, environmental advocates, and affected federal agencies. The first work group
was chartered in April 2007 and met through April 2010 to provide feedback on MOVES initial
development, culminating with the release of MOVES2010 in December 2009. A second work group met
from July 2012 through July 2013 during the development of MOVES2014, released in October 2014. A
third work group met from September 2016 through September 2021 to provide feedback on the
development of MOVES3, released in November 2020.32
Each work group was charged with reviewing information about MOVES development and providing
recommendations to the MSTRS. In turn, the MSTRS evaluated the work group recommendations and
decided how these issues should be reported to the Clean Air Act Advisory Committee (CAAAC), which,
under the Federal Advisory Committee Act (FACA), may formally give EPA collective advice. Notes and
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presentations from the MOVES3 workgroup meetings are available at
https://www.epa.gov/moves/moves-model-review-work-group.
7.3 Internal Testing
The MOVES development team performs rigorous testing throughout the model development life cycle.
This includes unit testing to ensure that every change to MOVES affects emissions and activity as
expected, and systematic integrated testing to ensure changes do not have unintended side effects. We
also test to ensure that Rates Mode and Inventory Mode generate the same output if used with
consistent inputs.
7.4 Beta Testing and Shared "Release Candidate"
Beginning in November 2022, a draft version of M0VES4 was tested by a small group of experienced
MOVES users who identified potential errors in the code and provided comments on the new features
and documentation, including the updated interface and database converter.
Furthermore, prior to the final release of M0VES4, we also posted a draft version of M0VES4 (referred
to as a "release candidate") to the MOVES GitHub site
(https://github.com/USEPA/EPA MOVES Model/releases/tag/MOVES4-RC2). This posting allowed
additional user testing and helped modelers to become familiar with functional changes between
M0VES3 and M0VES4 before MOVES4.0 was released.
7.5 Accessibility Testing
The M0VES3 graphical user interface was reviewed for accessibility under the Voluntary Product
Accessibility Template (VPAT).33 The interface partially supports the accessibility requirements.
Interface changes for M0VES4 were minimal and the M0VES3 VPAT is still applicable. We plan to
improve MOVES accessibility in future versions.
7.6 MOVES Sensitivity Analysis
A number of studies have been conducted to identify the input factors that are most important in
influencing MOVES results.34'35'36,37 In general, model year-and thus calendar year and age distribution-
- is important because it captures the decline in emissions as emission standards become more stringent
over time. Other factors such as vehicle speed and driving pattern, fuel parameters, humidity and
ambient temperature may also be important for specific vehicle categories, emission processes, and
pollutants. However, changes to MOVES emission factors, emission adjustments, and the relative
activity and vehicle population across MOVES versions can affect sensitivity greatly. This means that
one should not assume that sensitivity determinations developed for one version of MOVES are
accurate for other versions.
7.7 Evaluation by Industry-Funded Research Group
The MOVES2014 model was reviewed by the Coordinating Research Council, a non-profit corporation
supported by the energy and mobility industries. The review (CRC project E-101) included three distinct
task elements: (1) a critical evaluation of modeling methods, (2) inventory analyses applied to three
locations, and (3) a validation of the fuel methodology using independent data sources.38 The report
provided detailed recommendations in 10 areas. EPA used these recommendations to help prioritize
efforts for M0VES3 and published a detailed response.39
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An additional review (CRC project E-116) investigated MOVES2014 evaporative inputs.40 While the
feedback was valuable, most of the issues pointed out in this CRC report are expected to have very little
impact on the magnitude of the evaporative emissions computed by MOVES.
7.8 Comparisons to Independent Data
Evaluating the performance of the MOVES model in comparison to other measures is useful for
assessing the model's performance in accurately estimating current emission inventories and
forecasting emission trends. It also helps to identify areas in need of improvement, and guide future
work and research. However, it is not appropriate to evaluate MOVES by comparing against
measurements based only on a few vehicles, or without sufficiently customizing MOVES inputs to
account for the measurement conditions (e.g., fleet composition, vehicle activity, meteorology).
In our efforts to evaluate MOVES, we have prioritized comparisons for the major sources of emissions
(e.g., light-duty gasoline, heavy-duty diesel) and areas where significant independent data is available. In
assessing our results, we consider systematic bias observed across multiple data sources as indicative of
model underperformance. On the other hand, if the model predictions are generally within the
variability of independent measurements, it gives confidence that the model is predicting real-world
emissions reasonably well.
Evaluating vehicle emissions is complex. Lyu and coauthors summarized potential evaluation methods in
a 2021 review study and concluded that "selecting different measurements will significantly impact the
assessment of the vehicle emission results and the applicable scope of the measurements. Considering
the different influencing factors of the operating vehicle emissions will have an impact on the model
application of the vehicle emission evaluation."41 In addition, some aspects of emissions, such as start
and evaporative emissions, are particularly challenging to measure in the real world, and, thus, to
evaluate.
Evaluating MOVES emission rates may include comparisons to data from sources such as dynamometer
tests, remote sensing devices (RSD) and portable emission monitoring systems (PEMS). To capture rare
(but influential) high emitters, it is important that the data samples are large and diverse, and it is useful
when the comparison data represent known operating conditions (e.g., a pre-conditioned IM240 drive
cycle). Such comparisons are particularly valuable because the emission rates from the study can be
compared with MOVES emission rates using the same activity and fleet variables such as vehicle mix,
vehicle age, and vehicle operating mode. For example, a broad-based study was used to evaluate
MOVES2014b and subsequently to update high-power emission rates in MOVES3.42
A more recent study compared light-duty gasoline vehicle emissions measured with remote sensing to
emission rates from MOVES3. The study was intended to evaluate a new RSD methodology rather than
to judge the accuracy of MOVES and the authors noted differences in the time scale of measured
emissions and the resulting complication in determining emissions by VSP bin. However, they found that
their measured emission rates were in the same range as MOVES3 input rates for C02, CO, and NO.
Hydrocarbon emission rates were high compared to MOVES values. They suspect an error or noise in
their THC measurements. The relative effects of vehicle age were similar between the observed values
and those incorporated into MOVES3.43
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Other studies compare "localized composite" emissions, using composite emission measurements from
many vehicles by tunnel44 or roadside emission monitors45 where vehicle emissions are predominant
and vehicle activity and fleet mix can be accounted for to some degree. A strength of tunnel and
roadside measurements is that they can capture the large sample sizes of vehicles operating in real-
world conditions needed to measure 'fleet-average' emission rates. However, such comparisons may
not include all pollutants, and they only assess the operating conditions represented at the specific
location. And, as Simon, et al. demonstrated, the inferred emissions depend on the observation method
and the distance from the roadway.46 The heavy-duty exhaust technical report includes comparisons of
MOVES heavy-duty emission rates to tunnel and roadside measurements and examples of using such
data to update ammonia and N20 emissions.17 A near-road study that suggests increases in heavy-duty
diesel emissions with decreasing ambient temperature47 is discussed in more detail in the MOVES
adjustment report.15
While tunnel studies and remote sensing can measure real-world emissions from many vehicles in a few
locations, portable emission monitors can measure emissions from a smaller number of vehicles
throughout a real-world driving route. Frey and coauthors instrumented light-duty gasoline vehicles
driven on prescribed routes and compared their emissions to MOVES model projections, concluding that
the MOVES operating mode approach has good accuracy and moderate-to-high precision, explaining a
wide range of variability in emission rates,48 and that MOVES is highly accurate in locating measured
emission "hotspots," that is, segments of a driving route with emissions in the 80th and 90th
percentiles.49
At a more general level, some MOVES evaluations compare regional air quality model results from
models such as the Community Multiscale Air Quality Modeling System (CMAQ) with air quality monitor
and deposition data and satellite data. These "top-down studies" are useful to assess the overall
emissions contribution from all relevant emission sources to air quality measurements. Discrepancies
between air quality modeling predictions and measurements can point to deficiencies in the emissions
inventory but may be confounded with deficiencies in the air quality model (e.g., modeling transport,
boundary layer, deposition, transformation, and other physical and chemical processes). In addition,
top-down studies on their own cannot identify the individual sources in the emissions inventory that are
responsible for the modeling discrepancy.50,51
Like air quality studies, "macro-scale" fuel consumption studies are also useful, comparing "bottom-up"
fuel consumption as estimated by MOVES to "top-down" fuel tax data. These studies can help assess
MOVES large-scale vehicle activity estimates and fuel economy values.
55
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o
Regional Onroad
Emissions
W *
VMT, population,
activity estimates
Localized Composite
Emissions
operating mode & fleet
mix estimates
AIR QUALITY MONITOR
DATA
W ®
Y |CMAQ|
Other Sector Emissions
TUNNEL, ROADSIDE
MONITOR DATA
Emission
Rates
DYNO, RSD, PEMS DATA
Figure 7-1-MOVES evaluation opportunities at rising levels of generalization and uncertainty.
Fuel Consumption Comparisons
For MOVES3, we conducted a detailed comparison of the gasoline and diesel fuel consumption
estimated by MOVES and estimated by FHWA based on fuel tax data. The study noted a number of
caveats, such as uncertainties in the MOVES activity inputs, potential inaccuracies in the state-provided
fuel tax data, and difficulties in matching the vehicle categories covered by the two estimates-including
accounting for public vehicles excluded from the FHWA analysis and uncertainties in the methodology
used by FHWA to allocate between highway and off-road fuel use. For the calendar years in the
comparison, MOVES gasoline consumption was overestimated, but within 10 percent of FHWA
estimates, with better comparisons for more recent years. MOVES diesel consumption was also
overestimated but within 20 percent for all years except 2009 and within 10 percent for calendar years
2016 and later.52
For MOVES4, we repeated this comparison using the same methodology. The MOVES4 gasoline
consumption estimates were higher, reflecting an update to MOVES default fuel energy content for E10
gasoline (see the MOVES4 GHG and Energy report for details14) and a change in the age distribution with
more older cars and fewer vehicles covered by more stringent standards; thus, as illustrated in the
figures below, MOVES4 gasoline consumption compared less well to FHWA estimates, especially in past
years. Note that for performance purposes, certain inputs to MOVES do not capture changes over time,
such as relative mileage accumulation rates and fuel energy consumption. In these cases, given the
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importance of MOVES in forecasting future emissions, we have chosen updates such that MOVES better
represents current and future conditions rather than past.
FHWA
MOVES4
2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Calendar Year
Figure 7-2—National gasoline consumption (in billion gallons) by calendar year estimated by MOVES4 and FHWA.
The MOVES4 diesel comparisons were similar to MOVES3, with a close match in the most recent years.
50
I 40
5 30
i
E
3
Ifl
§ 20
O
re 10
o
B
FHWA
MOVES4
2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Calendar Year
Figure 7-3—National diesel consumption (in billion gallons) by calendar year estimated by MOVES4 and FHWA.
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N0X Evaluation Work
Several studies using emissions generated with versions of MOVES2014 have shown differences
between air quality model estimates and monitored values for nitrogen oxides. Researchers suggested
that air quality models appear to overestimate NOx ambient values due to an overestimate in NOx
emissions53,54,55 particularly from LD gasoline vehicles.56
In response, as part of MOVES3 development efforts, we evaluated the MOVES2014 light-duty emission
rates against in-use measurements and, based on the comparisons,4242, we updated the emission rates in
MOVES3, generally decreasing light-duty NOx emissions in MOVES3.
We also formed a cross-EPA workgroup to coordinate efforts to evaluate NOx emissions and modeling.
This effort concluded that:
Model over-predictions were likely due to multiple compounding factors that each contributed to a
portion of the bias. Based on our review of the evidence, the most important contributing factor to
the summer NOx bias was:
• Planetary boundary layer (PBL) and vertical mixing algorithms in the Community Multiscale Air
Quality (CMAQ) model (version 5.0.2 and earlier) led to too little vertical mixing at certain times
and in some locations. These algorithms have been improved in CMAQv5.1 and later versions of
CMAQ. These changes substantially reduced the NOx bias, as well as the NOx diurnal bias
pattern in simulations run with more recent CMAQ versions.
We also demonstrated that there is important uncertainty in the model bias caused by NOxand NOy
measurement uncertainty, as well as chemical mechanism used. Caution should be taken in using
modeled NOx bias to constrain NOx emissions or processes incorporated into air quality modeling.
Through this effort, we identified aspects of the mobile source NOx emissions that were
overestimated in the evaluated air quality platforms, but based on our analysis so far, mobile source
NOx only had a modest impact on the magnitude and pattern of the bias in modeled NOx
concentrations.57
The workgroup is no longer formally active, but EPA offices continue to work together to understand
and improve our emission and air quality models.
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8. Considerations When Using MOVES
The task of keeping MOVES current with manufacturers' ever-changing vehicle and equipment products,
activity data that reflect how these vehicles and equipment are used, and the evolving scientific
understanding of emissions can be daunting. We must prioritize our efforts on updates that will affect
emissions results the most, are of the most value for our users and have the largest impact on the
overall accuracy of the model.
So, while the functional scope of MOVES is large, the model is not designed to answer every possible
question about mobile source emissions. While there are areas of the model that rely on assumptions
or limited data, in many cases, these areas either have a small contribution to the total emissions
inventory or represent cases where no data was available (e.g., emission deterioration of MY 2010+
light-duty gasoline emissions).
When deciding whether to use MOVES for a given purpose, it is important to note the following features
of the MOVES design:
• MOVES is designed to model fleet-average emissions rather than the emissions of any specific
vehicle or piece of equipment.
• MOVES models the emissions from vehicles and equipment designed to meet emission standards in
the United States. There are considerable challenges to adapting the MOVES framework to other
nations, primarily related to the need for specific information about the emission performance and
activity of vehicles.58,59
• While MOVES models onroad and nonroad emissions in California, the MOVES defaults do not
capture all the details of California emission standards and control programs. Instead, California uses
California-specific models for modeling mobile sources.60
• MOVES allows users to "pre-aggregate" location and time-specific input data when modeling
emissions at the national and state level and overtime periods longer than one hour. Pre-
aggregating inputs to these larger scales is faster but reduces the model accuracy and precision
compared to modeling at a more detailed level and aggregating the results at the end.
• MOVES defaults generally characterize fleet characteristics and activity at the national level. To
accurately model emissions in a specific location, accurate local inputs must be used. For example,
MOVES national default information on vehicle fleet mix, including the fraction of electric vehicles,
does not capture the substantial variation by location.
• MOVES allows user input of many parameters, and therefore, the quality of model output will
depend on the quality of these inputs, as well as the appropriateness of the model defaults relied
on.
• MOVES algorithms calculate emissions based on physical and chemical principles, statistical
relationships, and use of good engineering judgement. We develop MOVES algorithms based on the
best available knowledge at the time, and emission relationships inferred from present emission
databases. MOVES algorithms have and will continue to be updated in future MOVES versions as our
knowledge of emission processes is updated.
• MOVES does not separately model hybrids or plug-in hybrids with a conventional gas or diesel
engine. Onroad hybrid vehicles meet the same emissions standards as conventional gasoline or
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diesel vehicles and are incorporated into the fleet average criteria pollutant, energy and C02
emissions for each model year in MOVES.
• MOVES uses the same estimates of vehicle activity regardless of fuel type, i.e., activity for vehicles
fueled by electricity and compressed natural gas are the same for vehicles fueled by gasoline and
diesel.
• MOVES includes default tampering and mal-maintenance rates that are used to derive heavy-duty
diesel emission rates, which cannot be updated by users. These rates were last updated for
MOVES2014 with many of the data and assumptions from studies conducted between 1988 and
2007.17 MOVES does not explicitly account for tampering and mal-maintenance of light-duty onroad
vehicles or nonroad equipment.
• MOVES is not designed to model the impact of grade at national or county levels. MOVES does allow
grade to be included at the project scale. The project scale allows modeling of a wide variety of
onroad drive cycles and grades; users should assess whether the modeled drive cycle is realistic at a
given grade for the project-scale analysis.
In addition, it is useful to understand the sources and process used to update the MOVES default data.
The MOVES4 updates were limited in scope as described in Section 2.3, above, so most emission rates
have not been updated since MOVES3. While the MOVES3 updates were based on millions of emission
test results, coverage varies depending on data availability. MOVES forecasts emissions up to calendar
year 2060; these estimates are necessarily based on forecasts and extrapolation from data available at
the time of analysis, generally 2021 or earlier. Consistent with MOVES purpose and design, MOVES relies
on multiple datasets and analysis methods to estimate emissions across model years, fuel types, vehicle
and engine types, and emission processes. Thus, fleet-average emission estimates and overall trends are
generally more robust than emission rates from individual vehicle types, model years, fuel types and
emission processes that may be based on a single data set or analysis.
Furthermore, due to MOVES priorities and data availability, some onroad inputs have not been updated
recently or have other notable limitations. For example, due to the small number of light-duty diesel
vehicles in the U.S. fleet, MOVES uses the same exhaust emission rates for light-duty diesel vehicles as
for light-duty gasoline vehicles.19 MOVES motorcycle emissions rates were last analyzed in 2010.61 Light-
duty gasoline running emission rates were updated for MOVES3 based on millions of test results, but
differences between "with l/M" and "non l/M" rates for THC, CO and NOx emission rates are based on
previous analysis, and LD gasoline start deterioration with age is derived from information on running
emissions.19 Evaporative emissions other than refueling also were not updated for MOVES3 or MOVES4,
and the refueling updates are based on a limited range of ambient temperatures, gasoline RVPs and
model years. Also, while MOVES3 updated the vehicle activity patterns used to estimate start and ONI
exhaust emissions, MOVES evaporative emission calculations rely on older, more limited, trip pattern
data.16
MOVES3 emission rate updates included updates to HD diesel running emissions rates based on analysis
of a substantial database of running emissions data from well-maintained heavy-duty diesel trucks, but
the values used to estimate heavy-duty emission deterioration with age were last updated for
MOVES2014. We also have fewer data on start and crankcase emissions. Forecasts of HD diesel start
emission rates for MY 2027 and later are based on tests of a single prototype engine. MOVES4 crankcase
changes are due to an updated algorithm but continue to use MOVES3 data. In addition, while we also
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updated rates for heavy-duty gasoline and heavy-duty CNG vehicles, data are sparse for these vehicles.
In particular, peer reviewers have suggested that we may be underestimating crankcase emissions from
CNG vehicles.17
MOVES4 brake and tire wear emission rates are based primarily on a literature review from 2006 and
2007.22 Some MOVES adjustment factors are based on testing of older vehicle technologies.215
Nonroad emissions estimates are generally based on more limited data than onroad emissions for both
emission factors and population and activity. Many of the onroad emissions factors are applied to the
nonroad emission factors due to a lack of nonroad data; therefore, several of the previously mentioned
limitations for onroad also apply to nonroad, with the added uncertainty of applying onroad factors to
nonroad engines. Since many of the source data and algorithms used to model nonroad equipment date
from the first release of EPA's NONROAD model in 1998, some recent industry trends, such as the
increased adoption of electric- or battery-powered equipment (e.g., lawn and garden equipment) and
transition from 2-stroke to 4-stroke engines, are not reflected in the model. We are currently working on
acquiring nonroad emissions and activity data to improve the emissions characterization of the nonroad
sector.
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9. M0VES4 Documentation
There is extensive documentation for MOVES, including guidance documents to help explain regulatory
requirements, user instructions, training materials, and technical reports.
MOVES documentation is available on the web at https://www.epa.gov/moves. In addition, user help is
built into the MOVES GUI. Information on installing and using M0VES4 is available at
https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves.
The MOVES source code is available at https://github.com/USEPA/EPA MOVES Model and
documentation relating to the code and the computer technology aspects of using MOVES are at
https://github.com/USEPA/EPA MOVES Model/tree/master/docs.
To cite MOVES4.0.0 in general:
USEPA (2023) Motor Vehicle Emission Simulator: MOVES4.0.0. Office of Transportation and Air Quality.
US Environmental Protection Agency. Ann Arbor, Ml. August 2023. https://www.epa.gov/moves
Table 9-1 lists the various documentation currently available for M0VES3 and provides information on
accessing each document.
Table 3-1 MOVES Documentation
jGeneral:
EPA Releases M0VES4
Mobile Source Emissions
Model: Questions and
Answers
Highlights the difference between
M0VES3 and earlier versions of
MOVES and explains EPA policy
on using M0VES3 in state
implementation plans and
transportation conformity
analyses
https://www.epa.gov/moves/latest-
version-motor-vehicle-emission-
simulator-moves#background
Frequently Asked
Questions
Answers to frequently asked
questions on MOVES installation,
use, terminology and output
https://www.epa.gov/moves/freque
nt-questions-about-moves-and-
related-models
MOVES Introduction and
Overview Webinars
Webinars describing MOVES
versions and their use
https://www.epa.gov/moves/moves-
training
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Using MOVES for Regulatory and Other Purposes:
Federal Register Notice
I of Availability
Announces the official release of
MOVES4 for use in SIP
development and transportation
conformity purposes in states
other than California.
https://www.epa.gov/state-and- (
local-transportation/policv-and- 1
technical-guidance-state-and-local- 1
transportation#emission 1
MOVES4 Technical
Guidance: Using MOVES
to Prepare Emission
Inventories for State
Implementation Plans
and Transportation
Conformity
Guidance on appropriate input
assumptions and sources of data
for the use of MOVES4 in SIP
submissions and regional
emissions analyses for
transportation conformity
purposes.
https://www.epa.gov/state-and- I
local-transportation/policv-and- I
technical-guidance-state-and-local- (
transportation#emission (
j MOVES4 Policy
Guidance: Use of MOVES
for State Implementation
Plan Development,
Transportation
Conformity, General
Conformity, and Other
Purposes
How and when to use the
MOVES4 for SIP development,
transportation conformity,
general conformity, and other
purposes.
https://www.epa.gov/state-and- !
local-transportation/policv-and- (
technical-guidance-state-and-local- (
transportation#emission 1
J j Additional Guidance
Other guidance covers MOVES at
the Project Scale (used for hot-
spot analyses), using MOVES to
model specific control programs
(e.g., replacing or retrofitting
older diesel vehicles and
equipment with cleaner
technologies), using MOVES to
conduct l/M performance
standard modeling analyses for
l/M SIPs, using MOVES to develop
port-related emissions
inventories, and using MOVES to
estimate GHGs
Until updated, existing guidance is
generally applicable to M0VES4
See https://www.epa.gov/state-and- I
local-transportation I
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Training & Cheat Sheets:
Onroad Cheat Sheet
Summarizes common tables and
https://github.com/USEPA/EPA MO
n/alues used to create onroad
VES Model/blob/master/docs/MOV
MOVES runs and interpret their
ES4CheatsheetOnroad.pdf
outputs.
Also available in the MOVES GUI
Help menu.
Nonroad Cheat Sheet
Summarizes common tables and
https://github.com/USEPA/EPA MO
k/alues used to create nonroad
VES Model/blob/master/docs/MOV
MOVES runs and interpret their
ES4CheatsheetNonroad.pdf
outputs.
Also available in the MOVES GUI
Help menu.
MOVES Hands-on
1
IA detailed hands-on course for
Will be posted at
Training
state and local agency staff who
https://www.epa.gov/moves/moves-
¦will use MOVES for developing
training#hands-on-training
emissions inventories for SIP and
conformity analyses. The course
is designed to be self-taught in
periods where no classes are
scheduled, or constraints prevent
attending an in-person course.
Users can work through the
modules and hands-on exercises
at their convenience.
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Project-Level Training for
Quantitative PM Hot-
Spot Analyses
EPA's training course on
implementing EPA's PM Hot-Spot
Guidance is a technical, hands-on
course geared toward state and
local agency staff. The course
focuses on using EPA's emission
model MOVES and EPA's
dispersion model AERMODto
complete quantitative PM hot-
spot analyses. The course can be
self-reviewed when training
sessions are not available.
The course is based on
MOVES2014b and still largely
applicable to MOVES4.
https://www.epa.gov/moves/moves-
training-sessions#hotspot
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Installation and Computer-Related Aspects of Using MOVES
Installation Suite Executable program to install
MOVES4 and all required
software. Instructions are
embedded in the installer
https://www.epa.gov/moves/latest-
version-motor-vehicle-emission-
simulator-moves#download
MOVES Installation How to resolve common
Troubleshooting installation issues
https://github.com/USEPA/EPA MO
VES Model/blob/master/docs/lnstall
ationTroubleshooting.pdf
Quick Start Guide to Hints on how to access data in
Accessing MariaDB Data new MariaDB installation
https://github.com/USEPA/EPA MO
VES Model/blob/master/docs/Quick
StartGuideToAccessingMariaDBData.
pdf
MOVES4 Database Explains use of tool to convert
Conversion Tool Help MOVES3 databases for use with
MOVES4
https://github.com/USEPA/EPA MO
VES Model/blob/master/database/C
onversionScripts/lnputDatabaseConv
ersionHelp.pdf
Speciation Profile Scripts Instructions for how to speciate
Tool Help MOVES output for air quality
modeling as a post-processing
step
https://github.com/USEPA/EPA MO
VES Model/blob/master/database/P
rofileWeightScripts/profileScriptHelp
.pdf
AVFT Tool Help Instructions on how to use the
pVFT Tool for building the AVFT
input table
https://github.com/USEPA/EPA MO
VES Model/blob/master/database/A
VFTTool/AVFTTool Help, pdf
Building LEV and NLEV Instructions on how to use the
Input Databases Help LEV/NLEV Tool in the MOVES GUI
https://github.com/USEPA/EPA MO
VES Model/blob/master/database/L
EV NLEVScripts/lnstructionsForLEV
NLEV Tool.pdf
ONI Tool Help Instructions on how to use the
ONI Tool when running MOVES in
rates mode with default off-
network idling activity
https://github.com/USEPA/EPA MO
VES Model/blob/master/database/
ON ITool/lnstructionsForON ITool.pdf
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Anatomy of a RunSpec
An overview of all of the fields
https://github.com/USEPA/EPA MO
contained in a MOVES RunSpec
VES Model/blob/master/docs/Anato
mvOfARunspec.md
Command Line MOVES
A brief guide on how to run
https://github.com/USEPA/EPA MO
MOVES and MOVES tools from
VES Model/blob/master/docs/Com
the command line
mandLineMOVES.md
Debugging MOVES
Tips for troubleshooting and
https://github.com/USEPA/EPA MO
debugging unexpected behavior
in MOVES runs
VES Model/blob/master/docs/Debu
ggingMOVES.md
MOVES Code: Folder by
Descriptions of the contents
https://github.com/USEPA/EPA MO
| Folder
within the folders in the MOVES
source code directory
VES Model/blob/master/docs/Folde
rBvFolder.md
1 MOVES Input/Output
Description of the schema
https://github.com/USEPA/EPA MO
| Database Changes
changes to MOVES County Scale IVES Model/blob/master/docs/lnput
and Project Scale input databases! OutputDBchanges.md
1 MOVES Database
Glossary of the column names
https://github.com/USEPA/EPA MO
| Glossary
used in the MOVES default
database
VES Model/blob/master/docs/MOV
ESGIossarv.md
i MOVES Database Tables
Schema descriptions for each
https://github.com/USEPA/EPA MO
|
table in the MOVES default
database
VES Model/blob/master/docs/MOV
ESDatabaseTables.md
i Tips for faster MOVES
Suggestions for how to structure
https://github.com/USEPA/EPA MO
! runs
MOVES runs to be as efficient as
VES Model/blob/master/docs/TipsF
|
possible
orFasterMOVESRuns.md
| MOVES4 Update Log
Chronological listing of updates
to MOVES3
https://www.epa.gov/moves/moves
4-update-log
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MOVES Algorithms and Default Inputs
Onroad Technical
Reports
Nonroad Technical
Reports
1 .ink to MOVES technical reports
lescribing the default inputs and
ilgorithms for the onroad
unctions of MOVES4 and earlier
*/IOVES versions
iink to MOVES technical reports
escribing the default inputs and
Igorithms for the nonroad
jnctions of MOVES4 and earlier
ersions Although the stand-
lone NONROAD model is now
icorporated into MOVES, many
fthe NONROAD technical
eports still apply to the nonroad
iputs and algorithms used in
/IOVES.
https://www.epa.gov/moves/moves-
onroad-technical-reports
https://www.epa.gov/moves/nonroa
d-technical-reports
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10.Acronyms
Acronym Meaning
AVFT Alternative vehicle fuels and technologies
BSFC Brake-specific fuel consumption
CH4 Methane
CI Compression ignition
CMAQ Community Multiscale Air Quality Modeling System
CO Carbon monoxide
C02 Carbon dioxide
EPA Environmental Protection Agency
EV Electric vehicle
FHWA Federal Highway Administration
HD Heavy duty
HD2027 Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine
and Vehicle Standards
HDGHG2 Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium-
and Heavy-Duty Engines and Vehicles—Phase 2
l/M Inspection and maintenance
LD Light duty
LHD Light Heavy-Duty
MOVES Motor Vehicle Emission Simulator
NMHC Non-methane hydrocarbons
NMOG Non-methane organic gases
NonHAPTOG Residual total organic gases
NOx Oxides of nitrogen
NREL National Renewable Energy Laboratory
PEMS Portable emission measurement systems
PM10 Particulate matter <= 10 pim
PM2.5 Particulate matter <= 2.5 pim
SAFE Safer Affordable Fuel Efficient Vehicles standard
SI Spark ignition
THC Total hydrocarbons
TOG Total organic gases
VMT Vehicle miles travelled
VOC Volatile organic compounds
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11. References
1 USEPA (2023). Fuel Supply Defaults: Regional Fuels and the Fuel Wizard in MOVES4. EPA-420-R-23-025 Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023
https://www.epa.gov/moves/moves-onroad-technical-reports
2 USEPA (2020). Fuel Effects on Exhaust Emissions from Onroad Vehicles in MOVES3. EPA-420-R-20-016. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. November 2020.
https://www.epa.gov/moves/moves-technical-reports.
3 USEPA (2005). Exhaust Emission Effects of Fuel Sulfur and Oxygen on Gasoline Nonroad Engines. NR-003c EPA-
420-R-05-016. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml.
December, 2005. https://www.epa.gov/moves/nonroad-technical-reports.
4 USEPA (2020). Air Toxic Emissions from Onroad Vehicles in MOVES3. EPA-420-R-20-022. Office of Transportation
and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. November 2020.
https://www.epa.gov/moves/moves-technical-reports.
5 USEPA (2023). MOVES4 Policy Guidance: Use of MOVES for State Implementation Plan Development,
Transportation Conformity, General Conformity, and Other Purposes. EPA-420-B-23-009. Office of Transportation
and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023. https://www.epa.gov/state-
and-local-transportation/policv-and-technical-guidance-state-and-local-transportation
6 https://www.epa.gov/moves/moves-training
7 USEPA (2023). MOVES4 Technical Guidance: Using MOVES to Prepare Emission Inventories for State
Implementation Plans and Transportation Conformity. EPA-420-B-23-001. Office of Transportation and Air Quality.
US Environmental Protection Agency. Ann Arbor, Ml. August 2023. https://www.epa.gov/state-and-local-
transportation/policv-and-technical-guidance-state-and-local-transportation
8 USEPA (2021). PM Hot-Spot Guidance: Transportation Conformity Guidance for Quantitative Hot-spot Analyses in
PM2.5 and PM10 Nonattainment and Maintenance Areas. EPA-420-B-21-037. Office of Transportation and Air
Quality. US Environmental Protection Agency. Ann Arbor, Ml. October 2021. https://www.epa.gov/state-and-local-
transportation/proiect-level-conformitv-and-hot-spot-analvses
9 USEPA (2021). Using MOVES3 in Project-Level Carbon Monoxide Analyses. EPA-420-B-21-047. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. December 2021.
https://www.epa.gov/state-and-local-transportation/proiect-level-conformitv-and-hot-spot-analvses
10 USEPA (2016) Using MOVES for Estimating State and Local Inventories of Onroad Greenhouse Gas Emissions and
Energy Consumption. EPA-420-B-16-059. Office of Transportation and Air Quality. US Environmental Protection
Agency. Ann Arbor, Ml. June 2016. https://www.epa.gov/state-and-local-transportation/estimating-greenhouse-
gas-emissions
11 88 FR 4296, January 24, 2023.
12 86 FR, December 30, 2021.
13 Truck Trailer Manufacturers Association, Inc. v. Environmental Protection Agency, No. 16-1430 (D.C. Cir. 2021)
14 USEPA (2023). Greenhouse Gas and Energy Consumption Rates for Onroad Vehicles in MOVES4. EPA-420-R-23-
026. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023.
https://www.epa.gov/moves/moves-onroad-technical-reports
15 USEPA (2023). Emission Adjustments for Onroad Vehicles in MOVES4. EPA-420-R-23-021 Office of Transportation
and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023
https://www.epa.gov/moves/moves-onroad-technical-reports
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16 USEPA (2023). Population and Activity ofOnroad Vehicles in MOVES4. EPA-420-R-23-005 Office of Transportation
and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023
https://www.epa.gov/moves/moves-onroad-technical-reports
"USEPA (2023). Exhaust Emission Rates of Heavy-Duty Onroad Vehicles in MOVE4. EPA-420-R-23-027. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023.
https://www.epa.gov/moves/moves-onroad-technical-reports
18 USEPA (2023). S peciation of Total Organic Gas and Particulate Matter Emissions from Onroad Vehicles in
MOVES4. EPA-420-R-23-006. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann
Arbor, Ml. August 2023. https://www.epa.gov/moves/moves-onroad-technical-reports
19 USEPA (2023). Exhaust Emission Rates for Light-Duty Onroad Vehicles in MOVES4. EPA-420-R-23-028. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023.
https://www.epa.gov/moves/moves-onroad-technical-reports
20 USEPA (2002). EPA's Onboard Analysis Shootout: Overview and Results. EPA-420-R-02-026. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. October 2002.
https://nepis.epa.gov/Exe/ZvPU RL.cgi?Dockev=P10005PG.TXT
21 Jaaskelainen, H. Crankcase Ventilation. DieselNet Technology Guide. www.DieselNet.com. Copyright © Ecopoint
Inc. Revision 2012.12.
22 USEPA (2020). Brake and Tire Wear Emissions from Onroad Vehicles in MOVES3. EPA-420-R-20-014. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. November 2020.
https://www.epa.gov/moves/moves-technical-reports.
23 USEPA (2023). Evaporative Emissions from Onroad Vehicles in MOVES4. EPA-420-R-23-023. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. August 2023.
https://www.epa.gov/moves/moves-onroad-technical-reports
24 USEPA (2018). Speciation Profiles and Toxic Emission Factors for Nonroad Engines in MOVES2014b. EPA-420-R-
18-011. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. July 2018.
https://www.epa.gov/moves/nonroad-technical-reports
25 USEPA (2005). Exhaust Emission Effects of Fuel Sulfur and Oxygen on Gasoline Nonroad Engines. NR-003c
EPA420-R-05-016, Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml
December 2005. https://www.epa.gov/moves/nonroad-technical-reports
26 USEPA (2005). Temperature Corrections for Nonroad Exhaust Emissions. NR-OOlc EPA-420-R-05-014. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. December, 2005.
https://www.epa.gov/moves/nonroad-technical-reports
27 USEPA (2010). Exhaust Emission Factors for Nonroad Engine Modeling - Spark-Ignition. NR-OlOf. EPA-420-R-10-
019. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. July 2010.
https://www.epa.gov/moves/nonroad-technical-reports
28 USEPA (2018). Exhaust and Crankcase Emission Factors for Nonroad Compression-Ignition Engines in
MOVES2014b. EPA-420-R-18-009. Office of Transportation and Air Quality. US Environmental Protection Agency.
Ann Arbor, Ml. July 2018. https://www.epa.gov/moves/moves-technical-reports
29 USEPA (2004). Refueling Emissions for Nonroad Engine Modeling. NR-013b EPA-420-P-04-013. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. April, 2004.
https://www.epa.gov/moves/nonroad-technical-reports
30 USEPA (2010). Nonroad Evaporative Emission Rates. NR-012d EPA-420-R-10-021. Office of Transportation and
Air Quality. US Environmental Protection Agency. Ann Arbor, Ml. July, 2010.
https://www.epa.gov/moves/nonroad-technical-reports
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31 USEPA (2015). Peer Review Handbook. 4th Edition. EPA/100/B-15/001. Science and Technology Council, US
Environmental Protection Agency. Washington, DC. October 2015.
https://www.epa.gov/sites/production/files/2020-08/documents/epa peer review handbook 4th edition.pdf
32 MRWG (2021) MOVES Review Work Group 2016-2021 Report to Mobile Sources Technical Review
Subcommittee, October 2021. https://www.epa.gov/svstem/files/documents/2022-01/mstrs-10-14-2Q21-meeting-
moves-review-workgroup-report.pdf
33 Schroeder, Walter (2020). EPA's Motor Vehicle Emission Simulator (MOVES) Accessibility Conformance Report,
Revised Section 508 Edition, Prepared for EPA Assessment and Standards Division, Office of Transportation and Air
Quality by Wild Goose Enterprises, Inc. Task Order 68HERD20F0154, August 14, 2020.
34 Choi, D (2010). MOVES Sensitivity Analysis: The Impacts of Temperature and Humidity on Emissions.
International Emission Inventory Conference, San Antonio, TX, September 2010
https://www3.epa.gov/ttn/chief/conference/eil9/session6/choi.pdf
35 Noel, George J. and Wayson, Roger L (2012). MOVES2010a regional level sensitivity analysis.DOT-VNTSC-FHWA-
12-05. https://rosap.ntl.bts.gov/view/dot/9706
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