EPA Releases "SmartWay SIP and
Transportation Conformity Guidance:
Accounting for NOx Reductions from
Trailer Aerodynamic Kits and Low-Rolling
Resistance Tires"
The U.S. Environmental Protection Agency (EPA) developed the
SmartWay Transport Partnership to reduce greenhouse-gas
emissions and air pollution from the ground freight-transport industry,
including long-haul diesel trucks. EPA has developed a guidance document
that describes how to quantify and use reductions in nitrogen oxides
(NOx) that result when trucks are outfitted with two specific SmartWay
fuel-efficient technologies: trailer aerodynamic kits and low-rolling
resistance tires.
EPA wants to encourage the adoption of SmartWay projects as a cost-effective
way to achieve NOx emission reductions needed for state air-quality plans (i.e.,
state implementation plans known as "SIPs") and transportation conformity
determinations.
How can SmartWay projects help in air-quality planning?
Because SmartWay aerodynamic kits and low-rolling resistance tires reduce
air pollution from trucks, these reductions can be quantified and used to help
demonstrate achievement of air-quality goals in a SIP or in a transportation
conformity determination. Therefore, this guidance is of interest primarily to ozone
and particulate matter (PM2.5 and PM10) nonattainment and maintenance areas
who are considering additional ways to reduce NOx for reasonable further progress
SIPs, attainment demonstrations, maintenance plans, or in transportation conformity
determinations.
A SmartWay project under this guidance may be part of a larger effort to provide
incentives for private and public agencies or truck owners to apply "SmartWay
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA420-F-07-045
June 2007
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Upgrade Kits" to a truck or fleet of trucks. The document released today provides the remaining
guidance needed for agencies to quantify and use the NOx reductions from SmartWay Upgrade
Kits in SIPs and conformity. Additional general information about the SmartWay Transport
Partnership, including the upgrade kits, can be found at: www.epa.gov/smartway/swresources.htm.
How are SmartWay trailer aerodynamic kits and low-rolling resistance tires
quantified for SIPs and transportation conformity determinations?
For states other than California, EPA recommends the use of the National Mobile Inventory
Model to estimate emission reductions from SmartWay aerodynamic kits and low-rolling
resistance tires for SIPs and for transportation conformity analyses. The model estimates the
impact of these technologies for the particular years to which they apply under local conditions.
Due to the nature of the aerodynamic kits and low-rolling resistance tires, emission reductions
from them will vary based on the average speed of the vehicles. See Chapter 2 of the guidance
for more information.
State and local agencies developing SIPs and conformity analyses for California should consult
with EPA Region 9 for information on the current version of the emissions factor model
approved for use in California and for information on how to apply Chapter 2 of this guidance
with California's model.
What are the basic requirements for using NOx reductions from aerodynamic kits
and low-rolling resistance tires in SIPs?
Chapter 3 of the guidance explains the basic requirements that all control measures must
meet to be included in a SIP. Emission reductions must be quantifiable, surplus, enforceable,
permanent, and adequately supported. These requirements can be met with aerodynamic trailer
kits and low-rolling resistance tires.
Can these SmartWay technologies be included in a SIP under the Voluntary
Measures policy guidance?
Yes. If emission reductions from these technologies are approved into the SIP under EPA's
Voluntary Measures policy guidance, the state is responsible for assuring that the reductions
credited in the SIP occur. The state would need to make an enforceable SIP commitment to
monitor, assess, and report on the emission reductions resulting from the voluntary measure, and
to remedy any shortfalls from forecasted emission reductions in a timely manner. See Chapter 3
of the guidance for more information.
How can NOx reductions from aerodynamic kits and low-rolling resistance tires be
included in transportation conformity?
Chapter 4 of the guidance covers this question in detail. Retrofits of highway vehicles (such as
buses and trucks) can be included in transportation conformity determinations without a SIP
revision by meeting the requirements in the conformity regulation at 40 CFR 93.122(a).
EPA Releases SmartWay SIP and Transportation Conformity Guidance
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For More Information:
• You can access the guidance at www.epa.gov/otaq/stateresources/transconf/policy.htm
• For more information about the SmartWay Transport program, visit: www.epa.gov/smartway
or contact Cheryl Bynum of EPA's Office of Transportation and Air Quality at
734-214-4844 or bynum.cheryl@epa.gov.
• For technical questions regarding the use of the National Mobile Inventory Model for
calculating emission reductions from aerodynamic kits and low-rolling resistance tires,
please e-mail mobile@epa.gov.
• For general questions concerning the use of NOx reductions from aerodynamic kits
and low-rolling resistance tires in SIPs or in transportation conformity, please contact
Laura Berry of EPA's Office of Transportation and Air Quality at 734-214-4858 or
berry.laura@epa.gov or Gary Dolce (also of OTAQ) at 734-214-4414 or
dolce.gary@epa.gov.
EPA Releases SmartWay SIP and Transportation Conformity Guidance
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