Policy Guidance on the Use of
MOVES3 for State Implementation
Plan Development, Transportation
Conformity, General Conformity,
and Other Purposes
£% United States
Environmental Protect
Agency
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Policy Guidance on the Use of
MOVES3 for State Implementation
Plan Development, Transportation
Conformity, General Conformity,
and Other Purposes
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
^1 Agency
EPA-420-B-20-044
November 2020
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Table of Contents
Introduction 2
1. What is the purpose of this guidance? 2
2. Why is this model called MOVES3? 3
3. What is MOVES3 and how does it compare to MOVES2014? 4
4. What resources are available to assist in implementing MOVES3? 6
5. Does this guidance create new requirements? 7
Using MOVE S3 in SIPs 7
6. How does the release of MOVES3 affect SIPs that are currently under
development? 7
7. How does the release of MOVES3 affect SIPs that have already been submitted or
approved? 8
8. When existing SIPs and budgets are revised with MOVES3, what do states need
to submit to show that a SIP continues to meet applicable requirements? 8
9. How will MOVES3 affect the need for emissions reductions in the development
of future attainment or maintenance SIPs? 11
10. What role will MOVES3 play in EPA's National Emissions Inventory? 12
Using MOVES3 in Transportation Conformity 12
11. When will the use of MOVES3 be required for regional emissions analyses in
transportation plan and TIP conformity determinations? 12
12. Under what circumstances will the MOVES3 grace period for regional emissions
analyses be shorter than two years? 13
13. How will the MOVES3 conformity grace period be implemented for regional
emissions analyses? 14
14. When will the use of MOVES3 be required for hot-spot analyses in project-level
conformity determinations? 15
15. How will the MOVES3 grace period be implemented for CO, PMio and PM2.5
hot-spot analyses? 16
16. How will MOVES3 affect FHWA's CO categorical hot-spot finding? 17
17. How will MOVES3 affect CO hot-spot protocols that were previously approved
into the SIP? 17
Using MOVES3 for General Conformity 17
18. When will the use of MOVES3 be required under the General Conformity Rule?
17
Using MOVES3 for Other Purposes 18
19. Can MOVES3 be used to estimate greenhouse gas emissions? 18
20. Can MOVES3 be used to estimate mobile source air toxics? 19
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Introduction
L. What is the purpose of this guidance?
This guidance describes how and when to use the latest version of the MOtor Vehicle
Emission Simulator (MOVES) emissions model for state implementation plan (SIP)
development, transportation conformity determinations, general conformity
determinations, and other purposes.1
MOVES3 is the U.S. Environmental Protection Agency's (EPA's) latest motor vehicle
emissions model for state and local agencies to estimate nitrogen oxides (NOx),
particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), carbon
monoxide (CO), and other pollutants/precursors from cars, trucks, buses, and motorcycles
for SIP purposes and conformity determinations outside of California.2
EPA will be publishing a Federal Register notice to announce the availability of
MOVES3 for official purposes. All states other than California should use MOVES3 for
future SIPs to take full advantage of the improvements incorporated in this version.
However, state and local agencies that have already completed significant work on a SIP
with MOVES20143 may continue to use it for that SIP. See Questions 6-10 for further
information on using MOVES3 in SIP development.
EPA intends to include in the Federal Register notice a two-year grace period for using
MOVES3 for regional transportation conformity purposes and a two-year grace period
for project-level conformity purposes.4 EPA coordinated with the U.S. Department of
Transportation (DOT) on the length of the grace period. MOVES3 will need to be used
for new regional emissions analyses for transportation conformity determinations begun
after the two-year grace period. MOVES3 will also need to be used for new PM and CO
hot-spot analyses for project-level conformity determinations begun after the two-year
project-level grace period. See Questions 11-17 for further information on using
MOVES3 in transportation conformity determinations. In addition, see Question 18 for
information on using MOVES3 in general conformity determinations.
EPA has also included information regarding the use of MOVES for estimating mobile
source air toxic (MSAT) and greenhouse gas (GHG) emissions. Although there are no
SIP or conformity requirements for these pollutants, MOVES3 is EPA's best tool for
estimating air toxics and greenhouse gas emissions from onroad mobile sources, for
regulatory purposes. See Questions 19 and 20 for further information.
1 This guidance, along with the other EPA guidance referenced in this document, is listed in the EPA
guidance portal at www.epa.gov/guidance/guidance-documents-managed-office-air-and-radiation.
2 In California, a different onroad emissions model, EMFAC, is used for regulatory purposes instead of
MOVES. MOVES can also model emissions in the District of Columbia, Puerto Rico, and the U.S. Virgin
Islands.
3 References to "MOVES2014" in this guidance relate to the previously released versions of MOVES2014,
MOVES2014a, andMOVES2014b.
4 See 40 C.F.R. 93.111(b).
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This guidance applies to the current version of MOVES3, as well as any future MOVES3
minor revisions.5 This guidance supersedes the previous July 2014 version of the
MOVES2014 guidance (EPA-420-B-14-008).
The following EPA contacts are available regarding this guidance:
• for general questions about the MOVES model, email mobile@epa.gov;
• for SIP questions, contact Rudy Kapichak or kapichak.rudolph@epa.gov;
• for transportation conformity questions, contact Astrid Terry or
terry.astrid@epa.gov;
• for general conformity questions, contact Virginia Raps or
raps.virginia@epa.gov. and
• for questions about the National Emissions Inventory, contact Janice Godfrey
or godfrev.ianice@epa.gov.
Questions about the application of this guidance to specific SIPs or transportation
conformity analyses should be addressed to the EPA Regional Office SIP or
transportation conformity contact. Regional contacts for transportation conformity can
be found at www.epa.gov/state-and-local-transportation/epa-regional-contacts-regarding-
state-and-1 ocal -transportati on.
A copy of this policy guidance can be found at the following website:
www.epa.gov/state-and-local-transportation/policv-and-technical-guidance-state-and-
local-transportation#emission.
Z Why is this model called M0VES3?
M0VES3 is a major revision to the previous versions of MOVES2014. EPA has
changed the naming system for MOVES with this revision. Under the new naming
convention, this model is M0VES3, as it is the third major MOVES release - the first
two were MOVES2010 and MOVES2014. As shown in Table 1, under this new naming
system, future minor revisions would be designated by increments of the number after a
decimal point (e.g., M0VES3.1, compared to using a new letter in the previous version,
e.g., MOVES2014a). EPA may also use an additional decimal point to designate minor
patches (e.g., MOVES3.0.1). This guidance should apply to all versions of M0VES3
until it is replaced with a new major revision.
5 Details on MOVES can be found at www.epa.gov/moves.
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Table 1: New MOVES Naming Convention
Type of Release
Naming Convention
Examples
Major release
"MOVES" followed by a new number
in sequence
MOVES3,
MOVES4
Minor revision
Addition of a decimal followed by a
new number in sequence
MOVES3.1,
MOVES3.2
Minor patch, e.g.,
new user features
Addition of a second decimal followed
by a new number in sequence
MOVES3.0.1,
MOVES3.0.2
The first model in the MOVES series, called MOVES2010, was released in December of
2009. MOVES2010 was followed by two minor updates, MOVES2010a and
MOVES2010b. Both of these minor MOVES2010 revisions enhanced model
performance and did not significantly affect the criteria pollutant emissions results from
MOVES2010. MOVES2014 was released in July 2014 and was a major revision to the
MOVES2010 versions of MOVES with new data, emissions standards, and functional
improvements and features. It incorporated substantial new data for emissions, fleet, and
activity developed since the release of MOVES2010. MOVES2014 was followed by two
minor updates, MOVES2014a and MOVES2014b. Both minor MOVES2014 revisions
enhanced model performance and did not significantly affect the onroad criteria pollutant
emissions results from MOVES2014.
References to "MOVES3" in this guidance relate to "MOVES3" and any future minor
revisions to MOVES3. References to "MOVES2014" in this guidance relate to all
versions of MOVES2014.
3^ What is MOVES3 and how does it compare to MOVES2Q14?
MOVES is EPA's state-of-the-art model for estimating emissions from onroad mobile
sources. MOVES3 also models most nonroad emissions sources.
MOVES3 is the newest MOVES model. It is a major update to previous versions of
MOVES. The model is based on analyses of millions of emission test results and
considerable advances in EPA's understanding of vehicle emissions. MOVES3
incorporates new regulations, features and significant new data, as detailed in the
MOVES3 technical reports. Notably, MOVES3 incorporates:
• Improvements to heavy-duty (HD) diesel running emission rates based on
manufacturer in-use testing data from hundreds of HD trucks;
• Updated emission rates for HD gasoline and compressed natural gas (CNG)
trucks;
• Updated light-duty (LD) vehicle emission rates for hydrocarbons (HC), CO and
NOx-based on in-use testing data;
• Updated LD PM rates for Model Year (MY) 2004 and later, incorporating data on
gasoline direct injection engines;
• New fuel characteristic data from EPA fuel compliance submissions;
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• Updated fuel effect calculations to better characterize the base fuel used to
develop LD base emission rates;
• The effects of the HD Phase 2 GHG rule;6
• The effects of the Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule on light-
duty fuel economy;7
• "Off-network idle" emissions beyond the idling that is already considered in the
MOVES drive cycles; and
• Several improvements to the MOVES interface, user inputs and outputs.
MOVES3 also includes a variety of activity updates, most notably:
• Vehicle start and idling activity patterns are based on real-world instrumented
vehicle data collected by a telecommunications company for LD vehicles and the
Department of Energy's (DOE) National Renewable Energy Lab (NREL) for HD
vehicles;
• Default hotelling activity has been substantially reduced from what was included
in MOVES2014 based on the NREL instrumented truck data;
• National vehicle miles travelled (VMT) and vehicle population inputs have been
updated with newer historical data from Federal Highway Administration
(FHWA) and more recent forecasts from DOE; and
• National onroad vehicle default fuel, regulatory class, and age distributions are
based on newer vehicle registration data.
MOVES3 includes the capability to estimate vehicle exhaust and evaporative emissions
as well as brake wear and tire wear emissions for criteria pollutants and precursors.
However, MOVES3 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.8
The structure of MOVES3 is fundamentally the same as MOVES2014, although there are
new format options for some inputs, and the model run time may differ depending on the
type of run and user inputs and computer configuration. As for emissions, EPA
performed a comparison of MOVES3 to MOVES2014b using default information in
MOVES3 at the national level, and for two sample urban counties with different local
travel patterns and ambient conditions. In general, compared to MOVES2014b,
MOVES3 national emission estimates are slightly lower for most criteria pollutants in
future years. However, in the two sample urban counties, NOx emissions estimates were
higher in future years. This is due to higher running emissions from heavy-duty trucks
outweighing declines from heavy-duty hotelling. Note that results will vary based on the
pollutant selected and that area's local inputs. Based on our testing, MOVES run time at
the Default and County Scale should be about the same or faster than runs with
6 81 FR 7348. October 25. 2016.
7 85 FR 24174. April 30. 2020.
8 See EPA's notice of availability, "Official Release of the January 2011 AP-42 Method for Estimating Re-
Entrained Road Dust from Paved Roads," published in the Federal Register on February 4, 2011 (76 FR
6328).
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MOVES2014b. In addition, as noted later in this document, MOVES3 run time at the
Project Scale may be notably longer compared to MOVES2014 depending on the type of
run, user inputs and computer configuration.
4 What resources are available to assist in implementing MOVES3?
In addition to this guidance document, EPA has developed technical guidance to assist in
implementing MOVES3:
• MOVES3 Technical Guidance: Using MOVES to Prepare Emission Inventories
in State Implementation Plans and Transportation Conformity (available at
www.epa.gov/state-and-local-transportation/policv-and-technical-guidance-state-
and-1 ocal-transportation#emission) provides guidance on how to set up a MOVES
run and add local data using the County Data Manager for SIPs and regional
transportation conformity analyses.
There are several existing MOVES2014 guidance documents that are still generally
applicable to using M0VES3 as well:
• Transportation Conformity Guidance for Quantitative Hot-spot Analyses in PM2.5
and PM10 Nonattainment and Maintenance Areas (available at
www.epa.gov/state-and-local-transportation/proiect-level-conformitv-and-hot-
spot-analyses) explains how to use MOVES to complete hot-spot analyses
required for projects of local air quality concern in PM2.5 and PM10 nonattainment
and maintenance areas.
• UsingMOVES2014 in Project-Level Carbon Monoxide Analyses (available at
www.epa.gov/state-and-local-transportation/proiect-level-conformity-and-hot-
spot-analyses) describes how to use the MOVES emissions model to estimate CO
emissions from transportation projects.
• Using MOVES for Estimating State and Local Inventories of On-Road
Greenhouse Gas Emissions and Energy Consumption - Final (available at
www.epa.gov/state-and-local-transportation/estimating-greenhouse-gas-
emissions) describes how to use MOVES to estimate greenhouse gas emissions
and/or energy consumption from onroad vehicles in a state or metropolitan area.
EPA will be updating these guidance documents following the release of M0VES3.
Where users are modeling with MOVES2014, please continue to refer to the
MOVES2014-based guidance.
Additional training materials, examples, and MOVES technical information are available
at the MOVES website: www.epa.gov/moves and at the Transportation Conformity
Training and Presentations website: www.epa.gov/state-and-local-
transportation/transportation-conformity-training-and-presentations.
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MOVES users are urged to check the MOVES website regularly and subscribe to EPA's
mobile source emissions model listserv to receive EPA email announcements related to
MOVES. Subscription information is found on the EPA's MOVES website at
www.epa.gov/moves/forms/epa-mobilenews-listserv.
5^ Does this guidance create new requirements?
No. The discussion in this document is intended solely as guidance. The statutory
provisions and EPA regulations discussed in this document contain legally binding
requirements. This document is not a regulation itself, nor does it change or substitute for
statutory provisions and regulations. Thus, it does not impose legally binding
requirements on EPA, the DOT, states, or the regulated community. EPA retains the
discretion to consider and adopt approaches on a case-by-case basis that may differ from
this guidance, but still comply with the statute and regulations. Any decisions regarding
a particular SIP or conformity determination will be made based on the statute and
regulations. This guidance may be revised periodically without an opportunity for public
comment.
Using MOVE S3 in SIPs
fr. How does the release of M0VES3 affect SIPs that are currently under
development?
M0VES3 should be used in ozone, CO, PM, and NO2 SIP development as expeditiously
as possible, as there is no grace period for the use of M0VES3 in SIPs. The Clean Air
Act (CAA) and implementation rules for the NAAQS require that SIP inventories and
control measures be based on the most current information and applicable models that are
available when a SIP is developed.9 However, EPA recognizes the time and level of
effort involved in SIP development. States should consult with their EPA Regional
Office if they have questions about how M0VES3 affects SIPs under development in
specific nonattainment or maintenance areas. Early consultation can facilitate EPA's
adequacy finding for transportation conformity purposes or for the SIP approval process.
States should use the latest version of MOVES that is available at the time that a SIP is
developed. All states other than California should use M0VES3 for SIPs that will be
submitted in the future so that they are based on the most accurate estimates of emissions
possible. However, state and local agencies that have already completed significant work
9 See Clean Air Act section 172(c)(3). Also see the discussion of emissions inventory requirements in the
"Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan
Requirements" rule (81 FR 58029, August 24, 2016) and in the "Implementation of the 2015 National
Ambient Air Quality Standards for Ozone: Nonattainment Area State Implementation Plan Requirements"
rule (83 FR 63022, December 6, 2018).
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on a SIP with MOVES2014 (e.g., attainment modeling has already been completed with
MOVES2014) may continue to rely on the earlier version of MOVES.
New regional emissions analyses that support transportation plan and transportation
improvement program (TIP) conformity determinations and are started after the end of
the conformity grace period must be based on the latest emissions model available. (40
CFR 93.111). Therefore, incorporating MOVES3 into the SIP now could assist areas in
mitigating possible transportation conformity difficulties in the future after the MOVES3
conformity grace period ends. See Question 11 for more information on using MOVES3
for regional emissions analyses and transportation plan and TIP conformity.
7. How does the release of MOVES3 affect SIPs that have already been submitted or
approved?
The CAA does not require states to revise submitted SIPs or SIPs that have already been
approved simply because a new motor vehicle emissions model is now available.10
States can choose to update these SIPs with MOVES3, for example, if it is determined
that it is appropriate to update motor vehicle emissions budgets ("budgets") with the
model for future conformity determinations.
However, as stated above, states should use MOVES3 where SIP development is in its
initial stages or has not progressed far enough along that switching from a previous
model version would create a significant adverse impact on state resources.
8. When existing SIPs and budgets are revised with MOVES3. what do states need to
submit to show that a SIP continues to meet applicable requirements?
As stated in Question 7, a SIP revision would not be required solely due to the release of
MOVES3 for SIPs that have been approved, submitted, or where significant development
has already occurred. However, there may be cases where an existing SIP that is based
on an older emissions model (e.g., MOVES2014 or MOVES2010) is revised with
MOVES3. As discussed below, in addressing these cases, EPA is applying the same
principles it has in the past when budgets have been revised using a new emissions
model. States should consult with their EPA Regional Office prior to submitting
MOVES3 SIP revisions. Early consultation can facilitate EPA's adequacy finding or SIP
approval process.
EPA cannot approve revisions to existing SIPs and budgets unless the revised SIP and
budget meets applicable CAA requirements (e.g., for reasonable further progress (RFP),
attainment, maintenance). If a state revises an existing SIP with MOVES3, it must show
10 Sierra Club v. EPA. 356 F.3d. 296, 308 (D.C. Cir. 2004) ("To require states to revise completed plans
every time a new model is announced would lead to significant costs and potentially endless delays in the
approval processes ")
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that the SIP continues to meet applicable requirements with the new level of motor
vehicle emissions calculated by the new model.
In addition, the transportation conformity rule (40 CFR 93.118(e)(4)(iv)) requires that
"the motor vehicle emissions budget(s), when considered together with all other
emissions sources, is consistent with applicable requirements for reasonable further
progress, attainment, or maintenance (whichever is relevant to the given implementation
plan submission)." This and other regulatory requirements must be satisfied before EPA
can find submitted budgets adequate or approve them for use in the conformity process.
The following describes how to meet applicable requirements for existing SIPs that are
revised with MOVES3, including ideas for how to streamline these revisions whenever
possible.
Use of latest planning assumptions: When SIPs are revised with MOVES3, the motor
vehicle emissions inventories for base year, milestone year and attainment/maintenance
year will need to be recalculated with the latest available planning assumptions. This
should include, at a minimum, the latest information for VMT, speeds, fleet mix, and SIP
control measures.11 Base year and historical year inventories should use the latest data
available for those years. Future year projection inventories should also be based on the
latest data available.12 If planning assumptions have not changed since the original SIP
was submitted, the state should document this in its new SIP submission.
In addition, states will need to consider and evaluate whether growth and control strategy
assumptions for non-motor vehicle sources (i.e., stationary, area, and nonroad mobile
sources) are still accurate at the time that the MOVES3 SIP revision is developed to
ensure the revised emissions inventories are consistent with the relevant applicable
requirement (e.g., RFP, attainment, or maintenance). Such assumptions include
population and economic assumptions and any allowable emissions relied upon for
stationary or other sources. If these assumptions have not changed, the state can explain
this and re-submit the original SIP with the revised motor vehicle emissions inventories
and budgets to meet the remaining requirements as discussed below. The state may also
in these cases provide summary emissions information for categories of sources and
references to the applicable portions of the original SIP, as long as those portions
continue to apply after the SIP revision with the MOVES3 budget is approved.
Otherwise, the emissions categories in the SIP that have changed should be brought up to
11 See EPA and DOT's joint "Guidance for the Use of Latest Planning Assumptions in Transportation
Conformity Determinations." EPA420-B-08-901, December 2008. This guidance also addresses
requirements for using the latest planning assumptions in SIP development. Also see the discussion of
emissions inventory requirements in the "Fine Particulate Matter National Ambient Air Quality Standards:
State Implementation Plan Requirements" rule (81 FR 58029, August 24, 2016) and in the "Implementation
of the 2015 National Ambient Air Quality Standards for Ozone: Nonattainment Area State Implementation
Plan Requirements" rule (83 FR 63022, December 6, 2018).
12 See the discussion of emissions inventory requirements in the "Fine Particulate Matter National Ambient
Air Quality Standards: State Implementation Plan Requirements" rule (81 FR 58029, August 24, 2016) and
in the "Implementation of the 2015 National Ambient Air Quality Standards for Ozone: Nonattainment
Area State Implementation Plan Requirements" rule (83 FR 63022, December 6, 2018).
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date to ensure that the emissions inventory is accurate, current, and consistent with the
relevant statutory requirements.13 States should consult with their EPA Regional Office
to determine what should be included in the SIP revision.
Milestone, attainment, or maintenance demonstration: As discussed above, SIP revisions
must continue to show that the SIP still meets applicable CAA requirements (e.g.,
attainment, maintenance, or interim milestones) when previous motor vehicle emissions
inventories are replaced with MOVES3 inventories. The level of analysis and support
needed for this demonstration can vary depending upon how MOVES3 affects the level
of motor vehicle emissions and whether non-motor vehicle inventories require updating.
The modeling and post-processing choices made in the original demonstration could also
be a factor.
Areas may be able to revise their motor vehicle emissions inventories and budgets using
MOVES3 without revising the entire SIP or completing additional modeling. This could
be the case if:
(1) the SIP meets applicable requirements when the previous motor vehicle
emissions inventories are replaced with MOVES3 base year and milestone,
attainment, or maintenance year inventories; and
(2) the state can document that the growth and control strategy assumptions for
non-motor vehicle sources continue to be valid and any minor updates do not
change the overall conclusions of the SIP.14
For example, if an ozone SIP relied on changes in emissions from the base year to an
attainment or maintenance year inventory to demonstrate attainment or maintenance, that
requirement would be satisfied by demonstrating that the relative emissions reductions
between the base year and the attainment or maintenance year are the same or greater
using MOVES3 than they were under the model previously used. Similarly, if an ozone
attainment SIP relied on absolute model predictions to demonstrate attainment for the
future attainment year, that requirement would be satisfied by demonstrating that the
MOVES3 estimates are equal to or lower than the previous estimates for the future
attainment year. Or, if a CO maintenance plan relied on either a relative or absolute
demonstration of maintenance, that requirement could be satisfied by documenting that
the relative emissions reductions between the base year and the maintenance year are the
same or greater using MOVES3.
If both 1 and 2 above are met, the state may be able to submit summary emissions
information for categories of sources and references to the applicable portions of the
original SIP as the needed SIP revision. States should consult with their EPA Regional
13 Id.
14 See the discussion of emissions inventory requirements in the "Fine Particulate Matter National Ambient
Air Quality Standards: State Implementation Plan Requirements" rule (81 FR 58029, August 24, 2016) and
in the "Implementation of the 2015 National Ambient Air Quality Standards for Ozone: Nonattainment
Area State Implementation Plan Requirements" rule (83 FR 63022, December 6, 2018).
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Office to determine what should be included in the SIP revision. However, if emissions
from other source categories in the SIP have changed, those inventories should be
brought up to date in order to demonstrate that the SIP submission complies with the
applicable statutory requirement for attainment, maintenance, or interim milestones. Any
changes in control strategies, including regulations that apply to stationary or area
sources and affect those portions of the inventories, will need to be factored in to both
base and future year inventories to determine whether the SIP still meets the applicable
statutory requirement. However, a state may not need to revise emissions for a non-
motor vehicle emissions inventory category, if a regulatory change resulted in a reduction
in emissions in the attainment or maintenance year relative to the existing SIP. In that
circumstance, the SIP could be assumed to continue to demonstrate attainment or
maintenance.
Regardless of the technique used, a more rigorous assessment of the SIP's attainment or
maintenance demonstration may be necessary if a state decides to reallocate the original
SIP's excess emissions reductions to the motor vehicle emissions budget as a safety
margin.15 In other words, the state will need to assess how its original demonstration is
affected by using MOVES3 and confirm whether excess emissions reductions exist prior
to allocating them to the budget. The assessment of the SIP's attainment or maintenance
demonstration, after onroad emissions are calculated using MOVES3, would need to be
sufficiently detailed to allow the state to determine the magnitude of the available safety
margin, if any, and to decide how much of the available safety margin to allocate to the
motor vehicle emissions budgets. This assessment is critical to ensure that SIP budgets in
the context of all other emissions sources continue to protect public health and meet the
conformity rule's adequacy criteria (40 CFR 93.118(e)(4)).
9. How will MOVES3 affect the need for emissions reductions in the development of
future attainment or maintenance SIPs?
The answer depends upon the unique circumstances of each nonattainment or
maintenance area. The emissions comparisons depend on the pollutants of concern, the
dates of concern, and on existing local regulations, travel activity patterns, fleet age, and
mix of cars and trucks. In some cases, a change from MOVES2014 to MOVES3 may
result in increased emissions estimates, while in other cases it may result in decreased
emissions estimates for the relevant time periods.
Moreover, because of the complex chemistry and meteorology of air pollution, the
implications of changes in onroad vehicle emissions may not be clear until multiple years
are examined, and the new emissions levels are applied in an air quality model. Relative
differences in emissions over time from MOVES2014 to MOVES3 may be as important
as, or more important than, differences between the models in any one year. Therefore,
15 A "safety margin" is the amount by which the total projected emissions from all sources of a given
pollutant are less than the total emissions that would satisfy the applicable requirement for reasonable
further progress, attainment, or maintenance (40 CFR 93.101). See also 40 CFR 93.124(a) for its
application.
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M0VES3 users should not immediately assume that increases or decreases in emissions
in any single year imply the need for more or fewer SIP control measures until those
changes in emissions have been applied in the complete SIP context.
An increase in emissions due to the use of MOVES3 may affect an area's ability to
demonstrate conformity for its transportation plan and/or TIP. Areas are encouraged to
consider, through interagency consultation, if and how MOVES3 will impact their future
conformity determinations and discuss any concerns with the appropriate EPA Regional
Office.
10. What role will MOVES3 play in EPA's National Emissions Inventory?
EPA will use MOVES3 for the 2020 National Emissions Inventory (NEI). The NEI is
updated with state, local, and tribal submissions once every three years. The most recent
NEI is the 2017 NEI and is available at www.epa.gov/air-emissions-inventories/2Q17-
national-emissions-inventory-nei-data.16 Mobile source emissions for the 2017 NEI were
generated with MOVES2014b with a mix of EPA and state-provided inputs.
Using MOVE S3 in Transportation Conformity
11. When will the use of MOVES3 be required for regional emissions analyses in
transportation plan and TIP conformity determinations?
EPA will be publishing a Federal Register notice to announce the availability of
MOVES3 for official purposes (outside of California). EPA, in consultation with DOT,
intends to establish a two-year grace period before MOVES3 needs to be used for
regional emissions analyses in transportation conformity determinations of transportation
plans and TIPs. Section 176(c)(1) of the CAA requires conformity determinations to be
based on "the most recent estimates of emissions." Additionally, the transportation
conformity rule (40 CFR 93.111) requires conformity analyses to be based on "the latest
emissions estimation model available," and further states that this requirement is satisfied
if the most current version of EPA's motor vehicle emissions model is used. When EPA
announces a new emissions model, such as MOVES3, we establish a grace period before
the model is considered the latest version of EPA's motor vehicle emissions model for
transportation conformity purposes (40 CFR 93.111(b)). In consultation with DOT, EPA
must consider several factors when establishing a grace period for conformity
determinations, including the degree of change in the emissions model and the effects of
the new model on the transportation planning process (40 CFR 93.111(b)(2)).
Transportation conformity is a CAA requirement to ensure that federally supported
highway and transit activities are consistent with ("conform to") the SIP. Conformity to
a SIP means that a transportation activity will not cause or contribute to new air quality
violations; worsen existing violations; or delay timely attainment of the national ambient
air quality standards or an interim milestone.
16 NEI on-road emissions for California are based on California's EMFAC model.
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EPA encourages state and local agencies to use the latest version of the MOVES model
available at the time that any conformity modeling begins, so that users can take
advantage of the latest information and improvements included in the model.
12. Under what circumstances will the MOVES3 grace period for regional emissions
analyses be shorter than two years?
The conformity grace period for regional emissions analyses will end two years after we
publish the Federal Register notice announcing MOVES3, unless new MOVES3-based
SIP budgets become applicable sooner, in which case the grace period will end for
specific areas and a specific pollutant once these new MOVES3-based approved or
adequate budgets become effective. In this case, the new regional emissions analysis for
that pollutant must use MOVES3 if the conformity determination is demonstrating
consistency with a MOVES3-based budget per 40 CFR 93.118. The interagency
consultation process must be used to develop any SIP revision based on MOVES3 (40
CFR 93.105(c)(l)(i)).
It is possible that areas that are designated nonattainment or maintenance for multiple
pollutants may rely on both MOVES3 and MOVES2014 to determine conformity for
different pollutants during the grace period. For example, if an area revises a previously
submitted (but not approved) MOVES2014-based PMio SIP with MOVES3 and EPA
finds these revised MOVES3 budgets adequate for conformity, such budgets would apply
for conformity on the effective date of the Federal Register notice announcing EPA's
adequacy finding. In this example, if an area was in nonattainment for PMio and ozone,
the MOVES3 grace period would end for PMio once EPA found the new MOVES3-
based SIP budgets adequate. However, MOVES2014 could continue to be used for
ozone conformity determinations until the end of the MOVES3 grace period for regional
emissions analyses.17
In addition, in most cases, if the state revises previously approved budgets based on an
earlier EPA emissions model SIP budget with MOVES3, the revised MOVES3 budgets
could not be used for conformity purposes until EPA approves them, i.e., approves the
SIP revision. In general, submitted SIPs cannot supersede approved budgets until the
submitted SIP is approved. See 40 CFR 93.118(e)(1).
However, 40 CFR 93.118(e)(1) allows an approved budget to be replaced by an
adequate budget if EPA's approval of the initial budgets specifies that the budgets being
approved may be replaced in the future by new adequate budgets. This flexibility has
been used in limited situations in the past. In such cases, the MOVES3-based budgets
would be used for conformity purposes once they have been found adequate, if
17 In this example, such an area would use MOVES3 to develop a regional emissions analysis for
comparison to the revised MOVES3-based budgets (e.g., PMio budgets). The regional emissions analysis
for ozone could be based on MOVES2014 for the VOC and NOx budgets in the ozone SIP for the
remainder of the conformity grace period.
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requested by the state in its SIP submission and if specified in EPA's SIP approval.
States should consult with their EPA Regional Office to determine if this flexibility
could be applied to their situation.
13. How will the MOVES3 conformity grace period be implemented for regional
emissions analyses?
During this two-year grace period, areas should use interagency consultation to examine
how MOVES3 will impact their regional emissions analyses and future transportation
plan and TIP conformity determinations. Isolated rural areas should also consider how
future regional emissions analyses will be affected when MOVES3 is required, if such an
analysis is anticipated. Areas should carefully consider whether the SIP and budget(s)
should be revised with MOVES3 or if transportation plans and TIPs should be revised
before the end of the conformity grace period, since doing so may be necessary to ensure
conformity in the future.
The conformity rule provides flexibility for analyses that are started during the grace
period. Regional emissions analyses that are started during the grace period can use
either MOVES2014 or MOVES3 (40 CFR 93.111(c)). Interagency consultation should
be used if it is unclear if a MOVES2014-based analysis was begun before the end of the
grace period.
When the grace period ends, MOVES3 will replace MOVES2014 as the current EPA
motor vehicle emissions model for transportation conformity purposes in states outside
California. In general, this means that all new regional emissions analyses started after
the end of the grace period will be based on MOVES3, even if the SIP is based on a
previous EPA emissions model. As discussed above, the grace period for new regional
emissions analyses would be shorter for a given pollutant if an area revised its SIP and
budgets with MOVES3 and such budgets were approved or found adequate for
conformity purposes prior to the end of the grace period. Also, when the grace period
ends, conformity determinations cannot rely on a previous emissions analysis that was
prepared using MOVES2014.
As discussed in more detail in the MOVES Technical Guidance, MOVES allows for
multiple approaches in developing a regional emissions analysis, which may result in
small differences in results.18 EPA recommends that the same approach be used in any
analysis that compares two or more cases (e.g., the SIP budget and the regional emissions
analysis for transportation conformity). Per 40 CFR 93.105(c)(l)(i), interagency
consultation must be used to evaluate and choose model or models and associated
methods and assumptions for conformity determinations. If different approaches are used
for the SIP budget and the regional emissions analysis for practical reasons, interagency
consultation should be used to determine how to address (and minimize) any differences
18 See the most current version of the MOVES Technical Guidance, available at www.epa.gov/state-and-
local-transportation/policv-and-technical-guidance-state-and-local-transportation#emission.
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in results. The methods used to develop inventories should be fully documented in the
SIP and conformity determination.
14. When will the use of MOVES3 be required for hot-spot analyses in project-level
conformity determinations?
EPA, in consultation with DOT, intends to establish a two-year grace period before
MOVES3 needs to be used for conformity hot-spot analyses outside of California, i.e.,
the same period of time as the grace period that will apply for conformity regional
emissions analyses. The Federal Register notice that announces the availability of
MOVES3 for official purposes will establish the grace period for both regional emissions
analyses and hot-spot analyses. The structure of MOVES3, including at the Project
Scale, is fundamentally the same as MOVES2014, although there are new format options
for some inputs, and the model run time may be notably longer compared to
MOVES2014 depending on the type of run, user inputs and computer configuration.
Hot-spot analyses are required to be included in conformity determinations for all non-
exempt FHWA/FTA projects in CO areas, and for "projects of air quality concern" in
PM2.5 and PM10 nonattainment and maintenance areas.19
Section 176(c)(1) of the CAA requires conformity determinations to be based on "the
most recent estimates of emissions." Additionally, the transportation conformity rule (40
CFR 93.111) requires conformity analyses to be based on "the latest emissions estimation
model available," and further states that this requirement is satisfied if the most current
version of EPA's motor vehicle emissions model is used. When EPA announces a new
emissions model, such as MOVES3, we establish a grace period before the model is
considered the latest version of EPA's motor vehicle emissions model for transportation
conformity purposes (40 CFR 93.111(b)). In consultation with DOT, EPA must consider
the degree of change in the emissions model and the effects of the new model on the
transportation planning process (40 CFR 93.111(b)(2)).
Once EPA announces the availability of MOVES3 in the Federal Register, MOVES3
will be the latest EPA motor vehicle emissions model for new conformity hot-spot
analyses outside of California and will need to be used in new analyses that begin after
the two-year grace period ends. The MOVES3 grace period for conformity hot-spot
analyses applies to the use of MOVES3 and any future minor revisions that occur during
the grace period.
EPA encourages state and local agencies to use the latest version of the MOVES model
available at the time that any conformity modeling begins, so that users can take
advantage of the latest information and improvements included in the model.
19 See 40 CFR 93.116 and 93.123 for more information.
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15. How will the MOVES3 grace period be implemented for CO. PMio and PM2.5 hot-
spot analyses?
EPA intends to establish a two-year conformity grace period for the use of MOVES3 for
CO, PM10 and PM2.5 hot-spot analyses, as stated above. See Question 11 for more
general information about the conformity grace period.
Sections 93.116 and 93.123 of the conformity regulations contains the requirements for
when a hot-spot analysis is required for project-level conformity determinations.20 In
addition, the conformity regulation provides flexibility for analyses that are started before
the end of the grace period. A conformity determination for a transportation project may
be based on a previous model if the analysis was begun before or during the grace period,
and if the final environmental document for the project is issued no more than three years
after the issuance of the draft environmental document (40 CFR 93.111(c)). Interagency
consultation should be used if it is unclear if a previous analysis was begun before the
end of the grace period.
For CO, PM10 and PM2.5 hot-spot analyses that start during the grace period, project
sponsors can choose to use MOVES2014 or MOVES3 as the current EPA motor vehicle
emissions model, since both are available during the grace period. The consultation
process must be used to determine which option may be most appropriate for a given
situation, per 40 CFR 93.105(c)(l)(i). Any new CO, PM10 or PM2.5 hot-spot analyses for
conformity purposes begun after the two-year grace period must be based on MOVES3.
EPA guidance on how to use MOVES for CO and PM hot-spot analyses is available (see
Question 4). Until EPA updates guidance to reflect the new model, the existing guidance
is still largely applicable to MOVES3. See EPA's Project-level Conformity website for
latest information and guidance documents on how to conduct CO, PM10 and PM2.5 hot-
spot modeling for transportation conformity purposes.
The length of the grace period for hot-spot analyses would not be affected by an early
submission of MOVES3-based SIP budgets. Using the same example as described in
Question 12, the two-year grace period would apply for PM10 hot-spot analyses even if
approved or adequate MOVES3-based budgets for PM10 are available before it ends.
Please consult with your EPA Regional Office (or Offices, where appropriate) if there are
questions about which model should be used in a project-level conformity determination.
20 In CO nonattainment and maintenance areas, a hot-spot analysis is required for all non-exempt projects,
with quantitative hot-spot analyses being required for larger, congested intersections and other projects (40
CFR 93.123(a)(1)). In addition, the conformity rule requires that a quantitative PM10 or PM2 5 hot-spot
analysis be completed for certain projects of local air quality concern (40 CFR 93.123(b)(1)).
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16. How will MOVES3 affect FHWA's CO categorical hot-spot finding?
FHWA released the updated CO categorical hot-spot finding for intersection projects on
July 17, 2017 that was based on MOVES2014a.21 During the MOVES3 grace period, a
project sponsor may continue to rely on the categorical finding for applicable projects
that are determined through interagency consultation to be covered by the finding's
parameters. Any new CO hot-spot analyses for conformity purposes begun after the end
of the MOVES3 grace period may no longer rely on the July 2017 CO categorical hot-
spot finding because the finding was based on MOVES2014.
17. How will MOVES3 affect CO hot-spot protocols that were previously approved into
the SIP?
Section 40 CFR 93.123(a)(1) of the transportation conformity regulation allows areas to
develop alternate procedures for determining localized CO hot-spot analyses, when
developed through interagency consultation and approved by the EPA Regional
Administrator. Some states have chosen in the past to develop such procedures based on
previously approved EPA emissions models.
During the MOVES3 grace period, areas with previously approved CO hot-spot protocols
based on MOVES2014 may continue to rely on these protocols. Once the MOVES3 two-
year grace period ends, new CO hot-spot analyses for conformity purposes will need to
be based on MOVES3 and thus may no longer rely on a CO hot-spot protocols based on
MOVES2014.
Using MOVE S3 for General Conformity
18. When will the use of MOVES3 be required under the General Conformity Rule?
CAA section 176(c)(4)(A) directs EPA to establish general conformity regulations for
federal actions not otherwise defined as a transportation action. General conformity is
implemented under 40 CFR part 93, subpart B and requires federal agencies to work with
state, tribal and local governments22 to ensure that emissions caused by a federal action
proposed to occur within a nonattainment or maintenance area do not interfere with (i.e.,
conforms to) the air quality plans established in the applicable implementation plan.23
The general conformity regulations in 40 CFR 93.159(b)(1) require a federal agency to
include in its applicability analysis24 an estimate of the action's motor vehicle emissions
using the most current version of the motor vehicle emissions model specified by EPA,
21 See www.epa.gov/state-and-local-transportation/proiect-level-conformitv-and-hot-spot-
analvses#cohotspot.
22 See 40 CFR 93.155 and 93.156 for General Conformity reporting and public participation requirements.
23 See 40 CFR 93.153 definition of Applicable implementation plan.
24 See 40 CFR 93.153 definition of Applicability analysis.
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unless the appropriate EPA Regional Administrator approves a modification or
substitution. When EPA updates its motor vehicle emissions model, a grace period of
three months shall apply during which a Federal agency may use the model previously
specified by EPA as the most current version, unless EPA announces a longer grace
period in the Federal Register 25 Since EPA intends to specify in the Federal Register a
two-year grace period before MOVES3 must be used, that grace period will apply for
general conformity analyses.26
The general conformity regulations provide flexibility if a Federal agency begins its
applicability analysis during the grace period announced in the Federal Register,
allowing the Federal agency to use either MOVES2014 or MOVES3.27 When the two-
year grace period ends, MOVES3 must be used for the general conformity applicability
analysis. If the Federal agency begins its applicability analysis within the three months
prior to the beginning of the grace period, the Federal agency may continue to use the
previous version of the model for its analysis.
If the motor vehicle emissions model specified by EPA is inappropriate for the action, a
Federal agency may, under 40 CFR 93.159(b), obtain written approval from the
appropriate EPA Regional Administrator for a modification or substitution of other
emission estimation techniques on a case-by-case basis, or on a generic basis for a
specific federal agency program.
Using MOVE S3 for Other Purposes
19. Can MOVES3 be used to estimate greenhouse gas emissions?
Yes, MOVES3 is currently the best tool EPA has for estimating GHG emissions from the
transportation sector for regulatory purposes and is a significant improvement over
MOVES2014. As described in Question 3, MOVES3 incorporates new emissions
standards not included in MOVES2014, as well as improved methane emission
algorithms and updated vehicle activity and population inputs. EPA notes that there are
no SIP and transportation conformity requirements for GHG emissions. State and local
agencies estimating GHG emissions in the transportation planning process should
consider using the latest version of MOVES in the future.
EPA has developed technical guidance28 that describes how to use MOVES to estimate
GHG emissions and/or energy consumption from onroad vehicles in a state or
metropolitan area. Until EPA updates this guidance to reflect the new model, the existing
MOVES2014 guidance is still largely applicable to MOVES3.
25 See 40 CFR 93.159(b)(l)(ii).
26 See 40 CFR 93.111(b)(1).
27 See 40 CFR 93.111(c).
28 The latest version of Using MOVES for Estimating State and Local Inventories of On-Road Greenhouse
Gas Emissions and Energy Consumption is available on EPA's website at www.epa. gov/state-and-local-
transportation/estimating-greenhouse-gas-emissions.
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20. Can MOVES3 be used to estimate mobile source air toxics?
Yes, MOVES3 estimates emissions for MSATs such as benzene, 1,3-butadiene,
formaldehyde, acetaldehyde, acrolein, naphthalene, and ethylbenzene.29 MOVES3 is
EPA's best available tool for quantifying emissions of these MSATs. State and local
agencies, academic institutions, and other interested parties who are interested in
analyzing MS AT emissions from transportation projects should consider using the latest
version of MOVES.
EPA notes that there are no SIP and transportation conformity requirements for air toxics.
Regarding the analysis of MS AT emissions in the National Environmental Policy Act
(NEPA) process, DOT has responsibility for implementing NEPA for federally funded or
approved transportation projects.
29 More information, including a list of the mobile source air toxics in MOVES, can be found in EPA's
report, Air Toxic Emissions from Onroad Vehicles in MOVES3, EPA-420-R-20-022, available at
www.epa.gov/moves/moves-onroad-technical-reports.
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