```

[Federal Register Volume 89, Number 238 (Wednesday, December 11, 2024)]
[Notices]
[Pages 99862-99866]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-29073]

-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

[FRL-12127-01-OAR]

Official Release of the MOVES5 Motor Vehicle Emissions Model for 
SIPs and Transportation Conformity

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA) is announcing the 
availability of the latest major release of the MOtor Vehicle Emission 
Simulator (MOVES) model, MOVES5, for official purposes outside of 
California. MOVES5 is the latest version of EPA's state-of-the science 
modeling tool for estimating emissions from cars, trucks, buses, and 
motorcycles based on the latest data and regulations. MOVES5 is 
available for use in state implementation plans (SIPs) and 
transportation conformity analyses outside of California. This notice 
starts a two-year grace period before MOVES5 will need to be used as 
the latest EPA emissions model for transportation conformity 
determinations outside of California, both in new regional emissions 
analyses and in new hot-spot analyses.

DATES: EPA's announcement of the MOVES5 emissions model for SIPs and 
transportation conformity determinations in states other than 
California is effective December 11, 2024. This announcement starts a 
two-year transportation conformity grace period that ends on December 
11, 2026. After this date, MOVES5 will need to be used as the latest 
EPA emissions model for new transportation conformity analyses outside 
of California in both regional emissions analyses and in hot-spot 
analysis.

FOR FURTHER INFORMATION CONTACT: For technical model questions 
regarding the official release or use of MOVES5, please email EPA at 
[email protected]. For questions about SIPs, contact Kaitlyn Leffert at 
[email protected]. For transportation conformity questions, 
contact Aaron Letterly at [email protected].

SUPPLEMENTARY INFORMATION: 
    The contents of this notice are as follows:

I. General Information

[[Page 99863]]

II. What is MOVES5?
III. SIPs and MOVES5
IV. Transportation Conformity and MOVES5

I. General Information

A. Does this action apply to me?

    Entities potentially impacted by the approval of MOVES5 are those 
that adopt, approve, or fund transportation plans, transportation 
improvement programs (TIPs), or transportation projects as defined in 
40 CFR 93.101 and those that develop and submit SIPs to EPA. Regulated 
categories and entities potentially affected by today's action include:

------------------------------------------------------------------------
                                                Examples of regulated
                 Category                             entities
------------------------------------------------------------------------
Local government..........................  Local air quality and
                                             transportation agencies,
                                             including metropolitan
                                             planning organizations
                                             (MPOs).
State government..........................  State air quality and
                                             transportation agencies.
Federal government........................  Department of Transportation
                                             (Federal Highway
                                             Administration (FHWA) and
                                             Federal Transit
                                             Administration (FTA)).
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by the 
release of MOVES. Other entities not listed in the table could also be 
affected. To determine whether your organization is affected by this 
action, you should carefully examine the transportation conformity 
applicability requirements in 40 CFR 93.102. If you have questions 
regarding the applicability of this action to a particular entity, 
consult the persons listed in the preceding FOR FURTHER INFORMATION 
CONTACT section.

B. How can I get copies of MOVES5 and other related information?

    The official version of the MOVES5 model and supporting 
documentation are available on EPA's MOVES website: https://www.epa.gov/moves. Individuals who want to receive EPA announcements 
related to the MOVES5 model can subscribe to the EPA-MOBILENEWS email 
listserv, which can be done at EPA's website at: https://www.epa.gov/moves/forms/epa-mobilenews-listserv.
    Available guidance on how to apply MOVES5 for SIPs and 
transportation conformity purposes can be found on EPA's transportation 
conformity website, https://www.epa.gov/state-and-local-transportation/policy-and-technical-guidance-state-and-local-transportation,\1\ 
including the ``MOVES5 Policy Guidance: Use of MOVES for State 
Implementation Plan Development, Transportation Conformity, General 
Conformity, and Other Purposes.'' (EPA-420-B-24-038, November 2024).
---------------------------------------------------------------------------

    \1\ Interested parties can find these documents under the 
``Emission Models and Conformity'' and ``Project-Level Conformity'' 
topics on this website.
---------------------------------------------------------------------------

    EPA will continue to update these websites as other MOVES support 
materials and guidance are developed or updated.

II. What is MOVES5?

    MOVES5 is EPA's latest official motor vehicle emissions model for 
state and local agencies to estimate volatile organic compounds (VOCs), 
nitrogen oxides (NOX), particulate matter (PM2.5 and 
PM10), carbon monoxide (CO), and other pollutants and 
precursors from cars, trucks, buses, and motorcycles for SIP purposes 
and transportation conformity determinations outside of California.\2\ 
The model is based on analyses of millions of emission test results and 
considerable advances in the Agency's understanding of vehicle 
emissions. MOVES5 is a major revision to the MOVES series of models. 
This model is the fifth major MOVES release.\3\
---------------------------------------------------------------------------

    \2\ MOVES can also model emissions in the District of Columbia, 
Puerto Rico, and the U.S. Virgin Islands. Nonattainment and 
maintenance areas located in California use the latest approved 
version of the Emission FACtor (EMFAC) model.
    \3\ For more information, see EPA's MOVES Versions in Limited 
Current Use website at https://www.epa.gov/moves/moves-versions-limited-current-use.
---------------------------------------------------------------------------

    MOVES5 includes new regulations, features, and significant new 
data, as detailed in the MOVES5 technical reports. Notably, MOVES5 
incorporates several important updates, including:
     Accounting for EPA's Light- and Medium-Duty Multi-
Pollutant Rule with higher projected electric vehicle (EV) fractions 
and more stringent standards for carbon dioxide (CO2), PM, 
non-methane organic gases (NMOG) and NOX.\4\
---------------------------------------------------------------------------

    \4\ See EPA's final rule, ``Multi-Pollutant Emissions Standards 
for Model Years 2027 and Later Light-Duty and Medium-Duty 
Vehicles,'' published in the Federal Register on April 18, 2024 (89 
FR 27842).
---------------------------------------------------------------------------

     Accounting for EPA's Heavy-Duty Greenhouse Gas Emissions-
Phase 3 Rule with higher projected EV fractions and updated energy 
consumption estimates for heavy-duty EVs.\5\
---------------------------------------------------------------------------

    \5\ See EPA's final rule, ``Greenhouse Gas Emissions Standards 
for Heavy-Duty Vehicles--Phase 3,'' published in the Federal 
Register on April 22, 2024 (89 FR 29440).
---------------------------------------------------------------------------

     Incorporating new data on light-duty (LD) and heavy-duty 
(HD) brake wear emissions.
     Expanding detailed calculations to vehicles up to 40 years 
old, instead of 30.
     Updating onroad and nonroad fuel properties for calendar 
year 2021 and later.
     Updated historical and forecast default vehicle miles 
travelled (VMT), vehicle populations, age distributions, and fuel 
distributions.
    For additional information on the updates included in MOVES5, 
please refer to the ``Overview of EPA's MOtor Vehicle Emissions 
Simulator (MOVES5),'' found at EPA's MOVES website. Specific 
information about MOVES5 inputs and algorithms can be found on EPA's 
websites for MOVES Onroad Technical Reports and MOVES Nonroad Technical 
Reports.\6\
---------------------------------------------------------------------------

    \6\ For more information, see EPA's MOVES website: https://www.epa.gov/moves.
---------------------------------------------------------------------------

    Like its predecessors, MOVES5 can estimate vehicle exhaust and 
evaporative emissions as well as brake wear and tire wear emissions for 
criteria pollutants and precursors. Also, like previous versions, 
MOVES5 does not estimate emissions of re-entrained road dust. To 
estimate emissions from re-entrained road dust, practitioners should 
continue to use the latest approved methodologies.\7\
---------------------------------------------------------------------------

    \7\ 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).
---------------------------------------------------------------------------

    The structure of MOVES5 is fundamentally the same as MOVES4, 
although there are some minor differences, e.g., in the user interface. 
However, inputs developed by model users for previous versions of MOVES 
will need to be updated to work with MOVES5. 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 onroad 
emissions from MOVES5 to emissions from MOVES4 using default 
information in MOVES5 at the national level, and for three sample urban 
counties with different local travel patterns and ambient conditions. 
In general, compared to MOVES4, MOVES5 emissions of NOX, 
PM2.5, VOC, and CO tend to be higher in the 2020s and 2030s. 
In the longer term, emissions of these pollutants in MOVES5 are lower 
due to the emissions reductions of new EPA regulations. Note that 
results will vary based on the pollutant selected and that area's local 
inputs.

III. SIPs and MOVES5

    EPA has articulated its policy regarding the use of MOVES5 in SIP 
development in its ``MOVES5 Policy

[[Page 99864]]

Guidance: Use of MOVES for State Implementation Plan Development, 
Transportation Conformity, General Conformity, and Other Purposes'' 
(EPA-420-B-24-038, November 2024). Today's notice highlights certain 
aspects of the guidance, but state and local governments should refer 
to the guidance for more detailed information on how and when to use 
MOVES5 in reasonable further progress SIPs, attainment demonstrations, 
maintenance plans, inventory updates, and other SIP submissions.
    MOVES5 should be used in ozone, CO, PM, and nitrogen dioxide 
(NO2) SIP development as expeditiously as possible, as there 
is no grace period for the use of MOVES5 in SIPs. The Clean Air Act 
requires that SIP inventories and control measures be based on the most 
current information and applicable models that are available when a SIP 
is developed.\8\ States other than California should use the latest 
version of MOVES that is available at the time that a SIP is developed, 
which is now MOVES5. Using MOVES5 for SIPs that will be submitted in 
the future ensures that they are based on the most accurate estimates 
of emissions possible.
---------------------------------------------------------------------------

    \8\ 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).
---------------------------------------------------------------------------

    However, EPA recognizes the time and level of effort involved in 
SIP development, so in cases where state and local agencies have 
already completed significant work on a SIP with MOVES4 (e.g., 
attainment modeling has already been completed with MOVES4), they may 
continue to rely on this earlier version. In addition, due to the fact 
that EPA is releasing multiple versions of MOVES in a short timeframe, 
MOVES3 may have already been used in SIP development. In areas where 
state and local agencies have already completed significant work on a 
SIP with MOVES3, MOVES3 may continue to be used in SIP development. EPA 
believes this would be only a limited number of cases. States should 
consult with their EPA Regional Office if they have questions about how 
MOVES5 affects SIPs under development in specific nonattainment or 
maintenance areas. Early consultation can facilitate EPA's adequacy 
finding for SIP motor vehicle emissions budgets for transportation 
conformity purposes or for the SIP approval process.
    The Clean Air Act 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.\9\ States can choose to 
update these SIPs with MOVES5, 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 MOVES5 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.
---------------------------------------------------------------------------

    \9\ 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.'')
---------------------------------------------------------------------------

    Incorporating MOVES5 into the SIP now could assist areas in 
mitigating possible transportation conformity difficulties in the 
future after the MOVES5 conformity grace period ends. New regional 
emissions analyses using EPA's emissions model that are started after 
the grace period is over must be based on MOVES5 (40 CFR 93.111), so 
having MOVES5-based SIP budgets in place at that time could provide 
more consistency with transportation conformity determinations. For 
complete explanations of how MOVES5 is to be implemented for SIP 
purposes, refer to the ``MOVES5 Policy Guidance: Use of MOVES for State 
Implementation Plan Development, Transportation Conformity, General 
Conformity, and Other Purposes.'' (EPA-420-B-24-038).

IV. Transportation Conformity and MOVES5

    Transportation conformity is required under CAA section 176(c) (42 
U.S.C. 7506(c)) to ensure that federally funded or approved highway and 
transit activities are consistent with (``conform to'') the purpose of 
the SIP. Conformity to the purpose of the SIP means that transportation 
activities will not cause or contribute to new air quality violations, 
worsen existing violations, or delay timely attainment of the relevant 
national ambient air quality standards (NAAQS) or any interim 
milestones. EPA's transportation conformity rule (40 CFR parts 51 and 
93) establishes the criteria and procedures for determining whether 
metropolitan transportation plans, TIPs, and federally supported 
highway and transit projects conform to the SIP. Transportation 
conformity applies to designated nonattainment and maintenance areas 
\10\ for transportation-related criteria pollutants: ozone, 
PM2.5, PM10, CO, and NO2.
---------------------------------------------------------------------------

    \10\ ``Maintenance areas'' are those areas that were initially 
designated nonattainment for a criteria pollutant and subsequently 
redesignated to attainment after 1990. Maintenance areas have SIPs 
developed under CAA section 175A. (40 CFR 93.101).
---------------------------------------------------------------------------

    In this notice, EPA is announcing the availability of MOVES5 for 
use in transportation conformity determinations outside of California. 
EPA is also establishing a two-year grace period before MOVES5 will 
need to be used in regional emissions analyses for transportation 
conformity determinations of transportation plans and transportation 
improvement programs (TIPs) \11\ and in hot-spot analyses for project-
level transportation conformity determinations which use EPA's 
emissions model. The MOVES5 grace period for regional emissions and 
hot-spot analyses applies to the use of MOVES5 and any future minor 
revisions that occur during the grace period.
---------------------------------------------------------------------------

    \11\ The grace period also applies in the case that a regional 
emissions analysis is done for a project not from a conforming 
transportation plan and TIP (i.e., a project in an isolated rural 
area). See the transportation conformity rule at 40 CFR 93.101 for 
the definition of an isolated rural area and 40 CFR 93.109(g) for 
how conformity is done in an isolated rural area.
---------------------------------------------------------------------------

    This MOVES5 grace period is separate and distinct from the two-year 
grace period established with the release of the previous version of 
the model, MOVES4. The two-year grace period established by EPA's 
September 2023 MOVES4 Notice of Availability in the Federal Register is 
unchanged by the release of MOVES5 and continues to be in effect until 
September 12, 2025.\12\ For more information, see the MOVES4 Notice of 
Availability in the Federal Register and the ``MOVES5 Policy Guidance: 
Use of MOVES for State Implementation Plan Development, Transportation 
Conformity, General Conformity, and Other Purposes'' (EPA-420-B-24-038, 
November 2024).
---------------------------------------------------------------------------

    \12\ See EPA's Notice of Availability, ``Official Release of the 
MOVES4 Motor Vehicle Emissions Model for SIPs and Transportation 
Conformity,'' published in the Federal Register on September 12, 
2023 (88 FR 62567).
---------------------------------------------------------------------------

    The remainder of this section describes how the transportation 
conformity grace period was determined and summarizes how it will be 
implemented, including those circumstances when the MOVES5 grace period 
could be shorter than two years for regional emissions analyses. 
However, for complete explanations of how MOVES5 is to be implemented 
for transportation conformity, including details about using MOVES5 
during the grace period, refer to the ``MOVES5 Policy Guidance: Use of 
MOVES for

[[Page 99865]]

State Implementation Plan Development, Transportation Conformity, 
General Conformity, and Other Purposes.'' (EPA-420-B-24-038).

A. Why is EPA establishing a two-year conformity grace period?

    Section 176(c)(1) of the Clean Air Act states that ``. . . [t]he 
determination of conformity shall be based on the most recent estimates 
of emissions, and such estimates shall be determined from the most 
recent population, employment, travel, and congestion estimates . . 
.''. Additionally, the transportation conformity rule (40 CFR 93.111) 
requires conformity determinations to be based on ``the latest emission 
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 in the conformity analysis. When EPA announces 
a new emissions model, such as MOVES5, we establish a grace period 
before the model needs to be used 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)). The transportation conformity rule provides that EPA 
will establish a grace period for new emissions models of between three 
and 24 months (40 CFR 93.111(b)(1)).
    EPA articulated its intentions for establishing the length of a 
conformity grace period in the preamble to the 1993 transportation 
conformity rule (November 24, 1993; 58 FR 62211):
    ``EPA and DOT [the Department of Transportation] will consider 
extending the grace period if the effects of the new emissions model 
are so significant that previous SIP demonstrations of what emission 
levels are consistent with attainment would be substantially affected. 
In such cases, States should have an opportunity to revise their SIPs 
before MPOs must use the model's new emissions factors.''
    In consultation with DOT, EPA considered the degree of change in 
MOVES5 and the effects of the new model on the transportation planning 
process (40 CFR 93.111(b)(2)). EPA considered the time it will take 
state and local transportation and air quality agencies to conduct and 
provide technical support for analyses. State and local agencies will 
need to become familiar with the MOVES5 emissions model and will need 
to convert existing data for use in MOVES5. Since 1993, the fundamental 
purpose of section 93.111(b) of the transportation conformity rule has 
been to provide a sufficient amount of time for MPOs and other state 
and local agencies to learn and employ new emissions models. The 
transition to a new emissions model for conformity involves more than 
learning to use the new model and preparing input data and model 
output. After model start-up is complete, state and local agencies also 
need to consider how the model affects regional emissions analysis 
results and whether SIP and/or transportation plan/TIP changes are 
necessary to assure future conformity determinations.
    The two-year conformity grace period also provides sufficient time 
for state and local agencies to learn and apply new technical guidance 
and training that reflect MOVES5. EPA provides guidance on how to run 
the latest MOVES version for SIP and transportation conformity purposes 
with the release of the model \13\ and is working to update other 
guidance documents and training materials as quickly as possible. 
Generally, existing guidance and training applies to MOVES5 as noted on 
EPA's website, and EPA will notify MOVES5 users when updates to these 
materials are available. Training materials will continue to address 
different levels of state and local expertise.
---------------------------------------------------------------------------

    \13\ Refer to EPA's ``MOVES5 Technical Guidance: Using MOVES to 
Prepare Emission Inventories for State Implementation Plans and 
Transportation Conformity,'' EPA-420-B-24-043, November 2024, 
available on EPA's website at: https://www.epa.gov/state-and-local-transportation/policy-and-technical-guidance-state-and-local-transportation.
---------------------------------------------------------------------------

    In addition, many agencies will be implementing the transition to 
MOVES5 for PM and CO hot-spot analyses for applicable projects in those 
nonattainment and maintenance areas, with each analysis potentially 
involving multiple state and local agencies. States with CO hot-spot 
protocols that were previously approved into the SIP (40 CFR 
93.123(a)(1)) that are based on a previous version of MOVES will need 
time to revise them. Finally, EPA considered the general time and 
monetary resource constraints in which state and local agencies 
currently operate. Upon considerations of all these factors, EPA is 
establishing a two-year grace period, which begins today and ends on 
December 11, 2026, before MOVES5 needs to be used for new 
transportation conformity analyses outside of California.

B. Circumstances When the MOVES5 Grace Period Will Be Shorter Than Two 
Years

    The MOVES5 grace period for regional emissions analyses will be 
shorter than two years for a given pollutant if an area revises its SIP 
and motor vehicle emissions budgets with MOVES5 and such budgets have 
been found adequate or approved into the SIP prior to the end of the 
two-year grace period. In this case, the new regional emissions 
analysis must use MOVES5 if the conformity determination is based on a 
MOVES5-based budget (40 CFR 93.111).
    Areas that are designated nonattainment or maintenance for more 
than one pollutant may rely on both MOVES5 and MOVES4 to determine 
conformity for different pollutants during the MOVES5 grace period. For 
example, if an area revises a previously submitted (but not approved) 
PM10 SIP with MOVES5 and EPA finds these revised MOVES5 
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 the area is 
nonattainment for PM10 and ozone, the MOVES5 grace period 
would end for PM10 regional emissions analyses once EPA 
found the new MOVES5-based SIP budgets adequate. However, MOVES4 could 
continue to be used for ozone-related regional emissions analyses begun 
before the end of the MOVES5 grace period.\14\ Refer to the MOVES5 
Policy Guidance for additional details.
---------------------------------------------------------------------------

    \14\ In this example, such an area would use MOVES5 to develop a 
regional emissions analysis for PM10 for comparison to 
the revised MOVES5-based budgets (e.g., PM10 budgets). 
The regional emissions analysis for ozone could be based on MOVES4 
for the VOC and NOX budgets in the ozone SIP for the remainder of 
the conformity grace period.
---------------------------------------------------------------------------

    In addition, the length of the MOVES5 grace period for hot-spot 
analyses would not be affected by an early submission of MOVES5-based 
budgets. In the above example, the two-year grace period for 
PM10 hot-spot analyses would continue to apply even if the 
grace period is shortened for regional PM10 conformity 
analyses. EPA Regional Offices should be consulted for questions 
regarding such situations in multi-pollutant areas.
    In addition, in most cases, if the state revises previously 
approved budgets based on an earlier EPA emissions model, the revised 
MOVES5 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

[[Page 99866]]

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 MOVES5-based budgets would be used for conformity 
purposes once they have been found adequate, if requested by the state 
in its SIP submission and specified in EPA's SIP approval. States 
should consult with their EPA Regional Office to determine if this 
flexibility applies to their situation.

C. Use of MOVES5 for Regional Emissions Analyses During the Grace 
Period

    During the conformity grace period, areas should use interagency 
consultation to examine how MOVES5 will impact their future 
transportation plan and TIP conformity determinations, including 
regional emissions analyses. Isolated rural areas should also consider 
how future regional emissions analyses will be affected when the MOVES5 
grace period ends. Areas should carefully consider whether the SIP and 
budgets should be revised with MOVES5 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.
    Finally, the transportation conformity rule provides flexibility 
for completing conformity determinations based on regional emissions 
analyses that use MOVES4 that are started before the end of the grace 
period. Regional emissions analyses that are started during the MOVES5 
grace period can use either MOVES5 or MOVES4. The interagency 
consultation process should be used if it is unclear if a MOVES4-based 
analysis was begun before the end of the grace period. If there are 
questions about which model should be used in a conformity 
determination, the EPA Regional Office can be consulted.
    When the grace period ends on December 11, 2026, MOVES5 will become 
the only EPA motor vehicle emissions model for regional emissions 
analyses for transportation conformity in states other than California. 
In general, this means that all new transportation plan and TIP 
conformity determinations started after the end of the grace period 
must be based on MOVES5, even if the SIP is based on MOVES4 or an older 
version of the MOVES model.

D. Use of MOVES5 for Project-Level Hot-Spot Analyses During the 
Conformity Grace Period

    The MOVES5 grace period also applies to the use of MOVES5 for CO, 
PM10 and PM2.5 hot-spot analyses. Sections 93.116 
and 93.123 of the transportation conformity regulation contain the 
requirements for when a hot-spot analysis is required for project-level 
conformity determinations.\15\ The transportation conformity rule 
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 MOVES5 grace period, project sponsors can choose to use 
MOVES5 or MOVES4. Any new CO, PM10 or PM2.5 hot-
spot analyses for conformity purposes begun after the end of the MOVES5 
grace period must be based on MOVES5.
---------------------------------------------------------------------------

    \15\ 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, in 
PM2.5 and PM10 nonattainment and maintenance 
areas, the transportation conformity regulation requires that a 
quantitative hot-spot analysis be completed for certain projects 
(see 40 CFR 93.123(b)(1)).
---------------------------------------------------------------------------

    Interagency consultation must be used to evaluate and choose 
model(s) and associated methods and assumptions to be used in hot-spot 
analyses and regional emissions analyses (40 CFR 93.105(c)(1)(i)). This 
includes which MOVES version to use for a hot-spot analysis. EPA 
encourages project sponsors to use the consultation process to 
determine which option may be most appropriate for a given situation. 
For questions about how the MOVES grace periods apply in a project-
level conformity determination, contact your EPA Regional Office.
    EPA has guidance on how to conduct quantitative PM2.5 
and PM10 hot-spot modeling for transportation conformity 
purposes, and on how to use MOVES for a CO hot-spot analysis. See EPA's 
``Project-level Conformity'' website, https://www.epa.gov/state-and-local-transportation/project-level-conformity-and-hot-spot-analyses, 
for the latest information and guidance documents on how to conduct CO, 
PM10 and PM2.5 hot-spot modeling for 
transportation conformity purposes.

E. FHWA's CO Categorical Hot-Spot Finding

    FHWA released the most recent CO categorical hot-spot finding for 
intersection projects on January 31, 2023, that was based on 
MOVES3.\16\ Until September 12, 2025, a project sponsor outside of 
California 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. However, any 
new CO hot-spot analyses for conformity purposes begun after September 
12, 2025, would not be able to rely on the MOVES3-based January 2023 CO 
categorical hot-spot finding.
---------------------------------------------------------------------------

    \16\ See https://www.epa.gov/state-and-local-transportation/project-level-conformity-and-hot-spot-analyses#cohotspot.
---------------------------------------------------------------------------

F. CO Hot-spot Protocols that Were Previously Approved into the SIP

    Section 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 previous EPA emissions 
models.
    During the MOVES5 grace period, areas with previously approved CO 
hot-spot protocols based on MOVES4 may continue to rely on these 
protocols. Once the MOVES5 two-year grace period ends, new CO hot-spot 
analyses for conformity purposes will need to be based onMOVES5 and 
thus may no longer rely on CO hot-spot protocols based on MOVES4 or 
earlier versions.

William Charmley,
Director, Assessment and Standards Division, Office of Transportation 
and Air Quality.
[FR Doc. 2024-29073 Filed 12-10-24; 8:45 am]
BILLING CODE 6560-50-P
```