EPA Releases "Draft MOVES2009" for
Comment: Questions and Answers
Q1. Why is EPA releasing Draft MOVES2009?
Al. Under the Clean Air Act (CAA), EPA is required to regularly update its
mobile source emissions model. EPA is continuously collecting data and con-
ducting emission studies to make sure the Agency has the best possible basis
for its assessment. This assessment, in turn, informs the development of EPAs
mobile source emissions models. MOBILE6.2 is currently the only model
approved to do State Implementation Plan (SIP) and conformity analyses
outside of California1. Draft MOVES2009 is the draft version of EPAs new
mobile source emissions model which, when finalized, will represent the
Agency's most up-tO'date assessment of mobile source emissions. It will also
incorporate changes based upon recommendations made to the Agency by
the National Academies of Science,
Q2. When will MOVES2009 be available for SIP and conformity analyses?
A2. When the final MOVES2009 is released later this year, it will replace MO-
BILE6.2 as the model states and local areas will use to develop emission
inventories for SIPs and conformity determinations. It will also be used to es-
timate the emission reduction benefits from a range of mobile source control
strategies. In conjunction with the official release of MOVES2009, EPA will
release several guidance documents, including guidance on when the official
MOVES2009 model will be required for SIP use and establishing what the
grace period will be before the final model will be required for new conformity
analyses.
For California, the approved model for these analyses is currently the EMFAC2007 model.
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA-420-F-09-019
April 2009
-------
Q3. Why has EPA changed the name of its mobile source model from "MOBILE"
to "MOVES"?
A3. The name "MOVES" is an acronym for "Motor Vehicle Emission Simulator." The name
change signals the new approach to projecting mobile source emissions being taken in
the new model. Specifically, the MOVES model is designed to improve upon the MO-
BILE6.2 model in two key respects. First, the MOVES model is based on a review of
the vast amount of in-use vehicle data collected and analyzed since the release of MO-
BILE6.2, including millions of emissions measurements from light-duty vehicles. Analy-
sis of this in-use data has enhanced EPA's understanding of how mobile sources contrib-
ute to emission inventories and it has also improved the Agency's understanding of the
relative effectiveness of various in-use control strategies. Second, the MOVES model
is designed to allow users much greater flexibility with input and output options. This
added flexibility allows EPA to easily update emissions data incorporated in MOVES and
will allow users to incorporate a much wider array of activity data to improve estimation
of local emissions,
Q4. What is the schedule for the release of a final MOVES2009?
A4. EPA plans to release a final, official version of MOVES2009 at the end of 2009. The
final version of MOVES2009 will replace MOBILE6.2 as the official approved emissions
model for SIPs and conformity analyses.
Between the release of draft and final versions of MOVES2009, EPA and the Federal
Highway Administration (FHWA) will be providing MOVES2009 training to state and
local users (training sessions will be posted and updated at http://www.epa.gov/otaq/mod-
els/moves/index.htm as they are scheduled).
During this time, EPA will also be accepting comments from users, and making any
necessary changes to the final model. EPA requests comments by July 2009 in order to
give the Agency sufficient time to review comments and make necessary changes in time
for the end-of-year release deadline. All comments should be submitted via e-mail to:
mobile@epa.gov.
In addition to training and on-going model development work, EPA will also produce
guidance documents during the draft review period. A technical guidance document will
address issues related to development of local input information for MOVES2009. A
second guidance document will describe how to use MOVES2009 and air quality models
to do project-level hotspot analyses. A third guidance document will address when final
MOVES2009 will be required for SIP use and will specify a grace period before the final
version of MOVES2009 is required for new conformity analyses. EPA plans to release all
of these documents in draft form for comment later in 2009. Final guidance documents
will be released along with the final version of MOVES2009. EPA will announce the re-
lease of the final model and the beginning of the conformity grace period in the Federal
J Register,
-------
Q5. How does Draft MOVES2009 compare to EPA's previous mobile source emis-
sion factor models?
A5. Unlike the EPA's previous mobile source emission models, Draft MOVES2009 has been
designed around a graphical user interface (GUI) using the open source database man-
agement software known as MySQL. Using this database approach to modeling allows
EPA to easily incorporate large amounts of in-use data from a wide variety of sources,
such as data from vehicle inspection and maintenance (I/M) programs, remote sensing
device (RSD) testing, certification testing, portable emission measurement systems, etc.
This approach also provides users much greater flexibility with regard to output choices.
Unlike earlier models which provided emission factors in grams-per-mile in fixed out-
put formats, Draft MOVES2009 output can be expressed as total mass (in tons, pounds,
kilograms, or grams) or as emission factors (grams-per-mile and in some cases grams-per-
hour). Output can be easily aggregated or disaggregated to look at emissions in a range
of scales, from national emissions impacts down to the emissions impacts of individual
transportation projects,
Q6. How does the current Draft MOVES2009 compare to previously released
drafts of MOVES?
A6. The first draft release of MOVES - MOVES2004 - was a proof-of-concept model that
only looked at two aspects of mobile source activity: well-to-wheel energy consumption
and greenhouse gas (GHG) impacts. MOVES2004 was then followed by the MOVES
Demo model, which was released in May 2007. MOVES Demo allowed potential users
to gain familiarity with what would be the basic structure for subsequent iterations of
the model but did not include the ability to model emissions of criteria pollutants. The
reason for the release of MOVES Demo was to get comments from likely users on the
user interface and other model functions. With Draft MOVES2009, EPA is releasing a
more refined version of the model for likely users to "test drive" and comment upon so
that EPA can resolve any issues and implement any improvements suggested in time for
the official release at the end of 2009,
Unlike MOVES Demo, Draft MOVES2009 does include the ability to model criteria
pollutant emissions and also includes additional features to simplify regional and project-
level analyses for SIP and conformity determinations. It should be noted, however, that
Draft MOVES2009 is not approved for use in either official SIP submissions to EPA or
for making conformity determinations due to reasons discussed in further detail below.
In addition, Draft MOVES2009 is not approved for quantitative particulate matter (PM)
2.5 or PM10 hot-spot analyses for project-level conformity determinations, nor is it to be
used for required emissions analyses needed to meet the National Environmental Policy
Act (NEPA).
Q7. What can Draft MOVES2009 be used for?
J A7. Draft MOVES2009 is a work-in-progress that is being released now to solicit user com-
ments that can be used to improve the official, final version of MOVES2009 scheduled
-------
vi
»H
-------
Cfl
these increases are based on data developed as part of EPA's Kansas City study, which
showed much higher PM2.5 emissions at low ambient temperatures than previously
known. For heavy -duty trucks, Draft MOVES2009 incorporates new data from a large
study of trucks conducted by the Coordinating Research Council (known as the CRC
E'55 study) which includes deterioration effects on in-use emissions. Draft MOVES2009
also models the impact of vehicle speed and load on PM emissions, showing very large
rates of PM generation in stop-and-go traffic conditions,
Q9. How are the changes in emission rates in Draft MOVES2009 anticipated to
affect attainment demonstrations?
A9. When considering how the change to MOVES2009 may affect attainment demonstra'
tions, the relative reduction in emissions between a base year and an attainment year
is often more important than absolute increases or decreases in emissions. Preliminary
modeling by EPA indicates larger relative reductions in PM2.5 and volatile organic com'
pound ( VOC) emissions over time in Draft MOVES2009 compared to MOBILE6.2, but
smaller NOx reductions. Once again, these results will vary based on local inputs in a
given nonattainment area, with local variations in fleet age distribution and composition
having a significant influence on the final results,
Q10. How are the changes in Draft MOVES2009 anticipated to affect I/M program
credit?
c/:
ft\
J
A10. The shift to the MOVES emissions model will also have an impact on the
sion reductions credited to I/M programs. Because of the updated data included in
MOVES2009, on average, such programs can expect to see roughly 20-70% less credit
than previously claimed, depending upon the criteria pollutant and evaluation year be-
ing considered. The reasons for this reduced credit are two-fold,
First, in the area of in-use deterioration, Draft MOVES2009 - like MOBILE6.2 before it
- continues the "good news" trend of in-use, light-duty vehicles staying cleaner, longer,
One side-effect of this trend is that I/M programs (which reduce emissions by identifying
cars in need of repair and getting them fixed) will achieve less SIP credit than previously
projected because there are fewer vehicles in need of repair than originally believed,
Second, Draft MOVES2009 reflects updated information regarding the public's response
rate to an illuminated "Check Engine" light for areas without I/M to create the incen-
tive for fixing a vehicle in need of emissions repairs. Previously, it was assumed that the
public response rate dropped off sharply as soon as the vehicle was outside its warranty
period. Data collected more recently by the Coordinating Research Council (CRC) sug-
gests, however, that the response rate is actually relatively high, even without I/M and/or
warranty coverage to act as an incentive. As a result, Draft MOVES2009 attributes
significantly less credit to OBD-based I/M than previously projected,
Taken together, these two aspects of Draft MOVES2009 result in I/M programs receiv-
ing roughly 20-70% less SIP credit than previously projected because data shows that
-------
I/M is not as important for enforcing OBD-triggered repairs as previously believed. The
emission reductions resulting from the public's voluntary response to OBD will now be
accounted for in the baseline emissions inventory as opposed to being credited to the
effects of I/M. As suggested above, this result is good news for the environment because
it means that in-use light-duty vehicles are continuing to stay cleaner, longer, and that
motorists are getting the message that the "Check Engine" light is not something to be
ignored
Qll. Why is EPA changing its estimates of vehicle emissions?
Al 1. Over the last ten years, EPA's in-use data about technologies such as Tier 2, OBD II and
enhanced evaporative emission control systems has dramatically improved. For MOVES,
EPA has been able to carefully study these newer technologies, examining millions of
results for light-duty vehicles. A detailed analysis of 70,000 vehicles in Arizona's I/M
program provided information on how vehicles from the late-1990's and early 2000's age,
Information on even newer vehicles was captured in nearly 2,000 manufacturer compli-
ance tests. Other I/M and remote sensing data and special purpose studies helped EPA to
better understand trends in HC, carbon monoxide (CO) and NOx emissions for light-
duty cars and trucks. EPA found little change in HC and CO from our original MO-
BILE6 projections, but a noticeable increase in NOx emissions.
Also in support of MOVES development, the Agency conducted a landmark study of
PM emissions, testing nearly 500 gasoline-fueled light-duty cars and trucks in Kansas
City, Missouri. Because PM emissions are technically difficult to measure, the Kansas
City study - a collaborative effort including EPA, the Department of Transportation
(DOT), the Department of Energy (DOE), and the automotive and petroleum industries
- represents the largest such study ever conducted. The Kansas City study confirmed that
PM emissions from light-duty gasoline-fueled vehicles are higher than earlier predicted,
and clearly showed that cold ambient temperatures can dramatically increase PM start
emissions. The MOVES model includes these dramatic increases in PM start emissions
at low temperatures,
EPA's understanding of emissions from heavy-duty vehicles has continued to improve
since our last model was issued. Most earlier heavy-duty emission rates were based on
certification tests of then-new, mid-1990's engines. For MOVES, EPA has been able to
analyze data on more than 400 in-use trucks, some in the laboratory and some with on-
road measurement equipment. This allowed the Agency to understand how real trucks
^^ pollute at a range of speeds and driving conditions. EPA also has been able to better
^^ incorporate emissions from heavy duty diesel crankcase ventilation and from extended
idling (also known as "hotelling") - two emission processes that were relatively unstud-
ied at the time MOBILE6.2 was developed. The incorporation of this additional data
(1 ^ accounts for the increases in heavy duty NOx and PM emissions reflected in MOVES,
Emission differences in MOVES are especially large for heavy duty PM emissions because
they reflect updated data on the effects of both speed and vehicle deterioration not pre-
J viously available.
rf
-------
OJ
J
It must be stressed that, despite the discussion above, Draft MOVES2009 is a draft model
and there will likely be some changes between the draft and final version with regard to
emission rates. Furthermore, emission rates in the official MOVES will eventually need
to be updated and improved as a result of future research. Future emission rate changes
will be easier, however, due to the improved structure of MOVES, which stores emission
rates in an easily updated database. EPA expects that future model updates will be more
frequent, resulting in a model that better reflects how changing vehicle technology and
control strategies affect the emissions inventory,
Q12. Why is EPA releasing a draft version of the MOVES model at this time?
A12. EPA is releasing Draft MOVES2009 now to give users the opportunity to gain practical
experience with MOVES2009's new user inputs and output formats, and to solicit user
comments in time to make additional improvements to the model prior to its official
release. User review of the draft model is essential because EPA staff cannot foresee and
test all the scenarios in which the MOVES model will be used. Identifying user concerns
quickly will allow EPA staff to address many concerns prior to December 2009. Meeting
the December 2009 release deadline is important so that states will be able to make use
of MOVES2009 for the next round of SIP submissions, which are expected to be due in
2012.
Q13. What should users know prior to using the Draft MOVES2009 model?
A13. As mentioned above, EPA is anticipating changes to Draft MOVES2009 based on its
own testing of the model. A list of these anticipated changes will be posted and updated
regularly at the MOVES website at http://www.epa.gov/otaq/models/moves/index.htm,
Users who believe they may have identified an issue with Draft MOVES2009 or need
technical support are asked to contact EPA at mobile@epa.gov with a description of the
issue. Please be sure to include electronic copies of both the input and output files that
illustrate the issue in question,
EPA also strongly recommends that potential users of Draft MOVES2009 take advantage
of training that will be offered jointly by EPA and FHWA so they can gain practical ex-
perience with running the model prior to its official release in December 2009 (training
opportunities will be posted at http://www.epa.gov/otaq/models/moves/index.htm as they
are scheduled). Concerning other recommended training, knowing MySQL is not neces-
sary for simple runs, but some basic knowledge of the MySQL database management soft-
ware package will give users greater flexibility to customize MOVES2009 outputs to meet
their needs. For more advanced analyses such as official SIP and/or conformity submis'
sions, it is highly recommended that states develop in-house expertise in using MySQL
prior to the official release of MOVES2009 in December,
Lastly, with regard to the computer system requirements needed to run the Draft
MOVES2009 model, EPA recommends the following minimum system specifications:
processor - dual-core; memory - 1 GB RAM; storage - 40 GB; operating system: Win-
dows XP or 32-bit Vista. As is often the case when running computer-based applications,
-------
a faster processor, more memory, and greater storage capacity will improve the speed at
which the model performs user runs,
Q14. Given that EPA anticipates changes to Draft MOVES2009, should state and
local modelers wait to try MOVES2009 until EPA releases the official version
in December 2009?
A14. EPA recommends that state and local modelers get trained and begin using Draft
MOVES2009 as soon as possible. Although every effort has been made to make
MOVES2009 as user-friendly as possible, it is a new model with different input require-
ments and different output formats. Users will need to think about how to collect and
process local input information in different ways, and they will need to develop new
methods for post-processing model output. Users should start making the shift now by
getting trained (visit http://www.epa.gov/otaq/models/moves/index.htm for information
on training opportunities) and by performing trial runs with Draft MOVES2009. EPAs
future SIP and conformity policy guidance will address the timing of using MOVES2009
for these official purposes.
------- |