[Federal Register Volume 67, Number 19 (Tuesday, January 29, 2002)]
[Notices]
[Pages 4254-4257]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-2125]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-7135-1]
Official Release of the MOBILE6 Motor Vehicle Emissions Factor
Model
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of availability.
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SUMMARY: EPA is approving and announcing the availability of the
MOBILE6 motor vehicle emissions factor model for official use outside
of California. MOBILE6 is the latest update to the MOBILE model for use
by state and local governments to meet Clean Air Act requirements.
Today's notice also starts time periods before MOBILE6 is required to
be used in certain state implementation plan (SIP) revisions and all
new transportation conformity analyses.
MOBILE6 is a major revision of the MOBILE model which calculates
air pollution emission factors from passenger cars and trucks. The new
model is based on new and improved data and a new understanding of
vehicle emission processes. MOBILE6 is also a more user-friendly
version of the model which allows users to better tailor their motor
vehicle emissions estimates to local conditions.
EPA strongly encourages areas to use the interagency consultation
process to examine how MOBILE6 will affect future transportation
conformity determinations, so, if necessary, SIPs and motor vehicle
emissions budgets can be revised with MOBILE6 or transportation plans
and programs can be revised as appropriate prior to the end of the
MOBILE6 conformity grace period.
DATES: EPA's approval of the MOBILE6 emissions factor model is
effective January 29, 2002. See below for further information regarding
how today's approval starts time periods after which MOBILE6 is
required in new transportation conformity analyses and certain SIP and
motor vehicle emissions budget revisions.
FOR FURTHER INFORMATION CONTACT: If you have questions on this notice,
please send an e-mail to EPA at [email protected] or contact EPA at (734)
214-4636 for technical model questions.
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SUPPLEMENTARY INFORMATION:
Availability of MOBILE6 and Support Materials
Copies of the official version of the MOBILE6 model are available
on EPA's MOBILE Web site, http://www.epa.gov/otaq/m6.htm. The MOBILE
Web site also contains the following support materials for implementing
the new model: a detailed MOBILE6 User's Guide; MOBILE6 training
materials; EPA's ``Policy Guidance on the Use of MOBILE6 for SIP
Development and Transportation Conformity'; EPA's ``Technical Guidance
on the Use of MOBILE6 for Emission Inventory Preparation'; and a list
of Frequently Asked Questions about MOBILE6. EPA will continue to
update this website in the future as other MOBILE6 support materials
are developed.
Individuals who wish to receive EPA announcements related to the
MOBILE model should subscribe to the EPA-MOBILENEWS e-mail listserver.
To subscribe to the EPA-MOBILENEWS listserver, write the following in
the body of the e-mail message: subscribe EPA-MOBILENEWS FIRSTNAME
LASTNAME where FIRSTNAME and LASTNAME is your name (for example: John
Smith) and send the e-mail to the EPA Listserver at
[email protected].
Your e-mail address will then be added to the list of subscribers
and a confirmation message will be sent to your e-mail address.
Whenever a message is posted to the EPA-MOBILENEWS listserver by the
listserver owner (the Assessment and Standards Division of the EPA
Office of Transportation and Air Quality), a copy of that message will
be sent to every person who has subscribed.
You can remove yourself from the list by sending another message to
the listserver address. This message must be sent from the same e-mail
address that you used to subscribe, and should contain the message:
unsubscribe EPA-MOBILENEWS
Availability of Related SIP Policies
In November 1999, EPA issued two memoranda articulating the policy
for use of interim MOBILE5-based Tier 2 estimates and subsequent
MOBILE6 SIP revisions. These memoranda are discussed in question 3 of
EPA's ``Policy Guidance on the Use of MOBILE6 for SIP Development and
Transportation Conformity.'' Copies of the memoranda are available at
EPA's transportation conformity Web site, http://www.epa.gov/otaq/transp/traqconf.htm.
I. What Is MOBILE6?
MOBILE is an EPA emissions factor model for estimating pollution
from on-road motor vehicles in states outside of California. MOBILE
calculates emissions of volatile organic compounds (VOCs), nitrogen
oxides (NOX) and carbon monoxide (CO) from passenger cars,
motorcycles, buses, and light-duty and heavy-duty trucks. The model
accounts for the emission impacts of factors such as changes in vehicle
emission standards, changes in vehicle populations and activity, and
variation in local conditions such as temperature, humidity, fuel
quality, and air quality programs.
MOBILE is used to calculate current and future inventories of motor
vehicle emissions at the national and local level. These inventories
are used to make decisions about air pollution policies and programs at
the local, state and national level. Inventories based on MOBILE are
also used to meet the federal Clean Air Act's state implementation plan
(SIP) and transportation conformity requirements.
MOBILE6 is the first major update of the MOBILE model since 1993.
The MOBILE model was first developed in 1978. It has been updated many
times to reflect changes in the vehicle fleet and fuels, to incorporate
EPA's growing understanding of vehicle emissions, and to cover new
emissions regulations and modeling needs. Although some minor updates
were made in 1996 with the release of MOBILE5b, MOBILE6 is the first
major revision to MOBILE since MOBILE5a was released in 1993.
EPA produced 48 technical reports explaining the data and analysis
behind the MOBILE6 estimates and the methods in the model. State and
local governments, industry, academia, and the general public were
previously offered an opportunity to comment on MOBILE6 technical
reports, which are currently posted on EPA's MOBILE6 Web site http://www.epa.gov/otaq/m6.htm.
MOBILE6 provides many more options for users to incorporate local
inputs than were possible in MOBILE5a or MOBILE5b. These new options
are provided for implementers to use if desired, and MOBILE6 defaults
are appropriate when local information is not available for MOBILE6
purposes. Users now have the option to adapt MOBILE to local conditions
and model special situations that are not reflected in the model's
defaults. MOBILE6 also has an updated structure that allows users to
create result files with emissions by hour of the day, and to segregate
start and running emissions. The new output uses standard database
formats to allow users to easily post-process their results. These
features will be useful for entering the emissions data into air
quality models and other tools that make use of motor vehicle emission
inventories. For further information regarding operating MOBILE6,
please refer to the MOBILE6 User's Guide and EPA's ``Technical Guidance
on the Use of MOBILE6 for Emission Inventory Preparation.'' Please see
Availability of MOBILE6 and Support Materials for how to obtain these
documents.
II. SIP Policy for MOBILE6
EPA has articulated its policy regarding the use of MOBILE6 in SIP
development in its ``Policy Guidance on the Use of MOBILE6 for SIP
Development and Transportation Conformity.'' 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 MOBILE6 in attainment and maintenance SIPs, inventory updates, and
other SIP submission requirements. See Availability of Related SIP
Policies to obtain the MOBILE6 policy guidance.
Although MOBILE6 should be used in SIP development as expeditiously
as possible, EPA also recognizes the time and level of effort that
States have already undertaken in SIP development with MOBILE5. States
that have already submitted SIPs or will submit SIPs shortly after
EPA's approval of MOBILE6 are not required to revise these SIPs simply
because a new motor vehicle emissions model is now available. States
can choose to use MOBILE6 in these SIPs, for example, if it is
determined that future conformity determinations would be ensured
through such a SIP revision. However, EPA does not believe that a
State's use of MOBILE5 should be an obstacle to EPA approval for SIPs
that have been or will soon be submitted, assuming that such SIPs are
otherwise approvable and significant SIP work has already occurred
(e.g., attainment modeling for an attainment SIP has already been
completed with MOBILE5). It would be unreasonable to require States to
revise these SIPs with MOBILE6 since significant work has already
occurred, and EPA intends to act on these SIPs in a timely manner.
States should use MOBILE6 where SIP development is in its initial
stages or hasn't progressed far enough along that switching to MOBILE6
would create a significantly adverse impact on State resources. For
example, SIPs that will be submitted later in 2002 should be based on
MOBILE6 since there is
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adequate time to incorporate the new model's results. MOBILE6 should be
incorporated into these SIPs since MOBILE6's emissions estimates are
based on the best information currently available, as required by Clean
Air Act section 172(c)(3) and 40 CFR 51.112(a)(1).
In addition, SIPs that EPA has already approved are not required to
be revised in most areas now that EPA has approved MOBILE6. As
discussed below, there are exceptions for certain nonattainment and
maintenance areas that have included interim MOBILE5-based estimates of
the federal Tier 2 vehicle and fuel standards (65 FR 6698).
In November of 1999, EPA issued two memoranda \1\ to articulate its
policy regarding States that incorporated MOBILE5-based interim Tier 2
standard benefits into their SIPs and motor vehicle emissions budgets
(``budgets''). Although these memoranda primarily targeted certain
serious and severe ozone nonattainment areas, EPA has implemented this
policy in all other areas that have made use of federal Tier 2 benefits
in air quality plans from EPA's April 2000 MOBILE5 guidance, ``MOBILE5
Information Sheet #8: Tier 2 Benefits Using MOBILE5.''
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\1\ November 3, 1999 EPA memorandum entitled, ``Guidance on
Motor Vehicle Emissions Budgets in One-Hour Ozone Attainment
Demonstrations,'' and November 8, 1999 EPA memorandum entitled, ``1-
Hour Ozone Attainment Demonstrations and Tier 2/Sulfur Rulemaking.''
Please see Availability of Related SIP Policies for how to obtain
these memoranda.
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All States whose attainment demonstrations or maintenance plans
include interim estimates of the Tier 2 standards have committed to
revise and resubmit their budgets within either 1 or 2 years of the
final release of MOBILE6 in order to gain SIP approval. States that
committed to revise their budgets within 2 years after MOBILE6 is
released also committed that conformity will not be determined during
the second year unless there are adequate SIP budgets in place that
were developed using MOBILE6. The effective date of today's Federal
Register notice will constitute the start of the 1 or 2-year time
periods for these SIP revisions. SIP revisions are due by January 29,
2003, for States that committed to revise budgets within one year of
MOBILE6's release. SIP revisions are due by January 29, 2004, for
States that committed to revise budgets within two years of MOBILE6's
release.
III. Transportation Conformity Policy for MOBILE6
Transportation conformity is a Clean Air Act 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
pollution violations; worsen existing violations; or delay timely
attainment of federal air quality standards.
The transportation conformity rule (40 CFR part 93) requires that
conformity analyses be based on the latest motor vehicle emissions
model approved by EPA. 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. . . .'' When we approve a new emissions model
such as MOBILE6, a grace period is established before the model is
required for conformity analyses. The conformity rule provides for a
grace period for new emissions models of between 3-24 months.
EPA articulated its intentions for establishing the length of a
conformity grace period in the preamble to the 1993 transportation
conformity rule (58 FR 62211):
EPA and [the Department of Transportation (DOT)] 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 the DOT, EPA considers many factors in
establishing the length of the grace period, including the degree of
change in emissions models and the effects of the new model on the
transportation planning process (40 CFR 93.111).
Upon consideration of all of these factors, EPA is establishing a
2-year grace period, which begins today and ends on January 29, 2004,
before MOBILE6 is required for new conformity analyses in most cases.
During this grace period, areas should use the interagency consultation
process to examine how MOBILE6 will impact their future conformity
determinations.
However, the grace period will be shorter than 2 years for a given
pollutant if an area revises its SIP and budgets with MOBILE6 and such
budgets become applicable for conformity purposes prior to the end of
the 2-year grace period. For example, if an area revises a previously
submitted (but not approved) MOBILE5-based ozone SIP with MOBILE6 and
EPA finds the revised MOBILE6 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 ozone and CO, the MOBILE6 grace period
would end for ozone once EPA found the new MOBILE6-based ozone SIP
budgets adequate, but MOBILE5 could continue to be used for CO
conformity determinations until the end of the general MOBILE6 grace
period.
During the grace period, areas can use an approved version of
MOBILE5 \2\ for conformity determinations or choose to use MOBILE6 on a
faster time frame. When the grace period ends on January 29, 2004,
MOBILE6 will become the only approved motor vehicle emissions model for
new transportation conformity analyses outside of California. In
general, this means that all new VOC, NOX, and CO conformity
analyses started after the end of the 2-year grace period must be based
on MOBILE6, even if the SIP is based on an earlier version of the
MOBILE model. As discussed above, the grace period for new conformity
analyses would be shorter for a given pollutant if an area revised its
SIP and budgets with MOBILE6 for such pollutant and such budgets became
applicable for conformity purposes prior to the end of the 2-year grace
period. EPA strongly encourages areas to use the consultation process
to examine how MOBILE6 will affect future conformity determinations,
so, if necessary, SIPs and budgets can be revised with MOBILE6 or
transportation plans and programs can be revised as appropriate prior
to the end of the grace period.
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\2\ Please refer to EPA's Office of Transportation and Air
Quality's August 11, 1997 memorandum entitled, ``Summary of Comments
on and Guidance for Use of MOBILE5b,'' which describes our policy on
when MOBILE5a or 5b can be used in conformity determinations.
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For consistency purposes, EPA encourages areas that have
incorporated interim MOBILE5-based Tier 2 estimates into their SIPs to
continue to use MOBILE5 (instead of MOBILE6) for conformity analyses
until new MOBILE6 budgets are submitted and found adequate (unless the
grace period ends before this occurs). These areas have committed to
submit SIP revisions within 1-2 years of MOBILE6's release, therefore
conformity budgets based on MOBILE6 should be in place by the end of
the grace period.
Finally, the conformity rule provides some flexibility for analyses
that are started before or during the grace period. Regional conformity
analyses
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that began before the end of the grace period may continue to rely on
an approved version of MOBILE5. Conformity determinations for
transportation projects may also be based on an approved version of
MOBILE5 if the regional analysis was begun before the end of 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 (see 40 CFR 93.111(c)). The interagency
consultation process should be used if it is unclear whether a MOBILE5-
based analysis was begun before the end of the grace period.
Dated: January 23, 2002.
Margo Tsirigotis Oge,
Director, Office of Transportation and Air Quality, United States
Environmental Protection Agency.
[FR Doc. 02-2125 Filed 1-28-02; 8:45 am]
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