Office of Transportation EPA420-F-06-059
and Air Quality August 2006
United States
Environmental Protection ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^—^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^—
Agency
Regulatory
Announcement
Highway Heavy-Duty Diesel Engine
Regulatory Amendments
The U. S. Environmental Protection Agency (EPA) is publishing a Direct
Final Rule to incorporate some technical amendments to regulations
related to highway heavy-duty diesel engines.
Background
EPA initiated this rulemaking change to improve the technical approach
in the current regulations and to add a provision to allow highway diesel
engine manufacturers the ability to use an additive deterioration fac-
tor as default for heavy-duty highway diesel engines. This change to
the rule would harmonize our approach for highway heavy duty with
the approach we took for nonroad diesel for the same technologies in
1039.240(c)(l). It is only an option that requires use of good engineering
judgment and manufacturers are not required to use an additive DF.
Additive Deterioration Factor Option for Heavy-Duty
Diesels
This Direct Final Rule establishes deterioration factor provisions appli-
cable to a highway heavy-duty engine identical to the options available
to nonroad certified heavy-duty diesel engines certified under 40 CFR
1039.240. Additive deterioration factors are already allowed for chas-
sis-certified heavy-duty engines between 8,500 and 14,000 pounds gross
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vehicle weight rating (GVWR). The new
provision:
• Adds additive deterioration factors for
heavy-duty diesel engines equipped
with aftertreatment.
• Requires the use of multiplicative
deterioration factors if, based on good
engineering judgment, they are more
appropriate for a particular engine fam-
ily.
• Streamlines and harmonizes the calcu-
lation method for deterioration factor
determination.
There is no environmental impact asso-
ciated with this regulatory action. This
rulemaking does not change the heavy-duty
highway diesel engine emission standards
that manufacturers have to meet or the
requirement that these standards be met
throughout the useful life of the engines.
Rather, this action provides an option for
manufacturers regarding how they can
calculate the projected deterioration of the
engines emissions. In addition, EPA does
not expect that these minor revisions will
have any adverse cost impact to the manu-
facturers, and there are no new testing costs
associated with these revisions.
Public Participation
Opportunities
This rule is being released as a direct final
rule because we view it as a non-controver-
sial action and anticipate no adverse com-
ment. However, comments can be submit-
ted under a parallel Notice of Proposed
Rulemaking. For instructions on submitting
written comments, please see the Federal
Register notice, which is available from the
Web site below or from the EPA Air and
Radiation Docket (202-566-1742; please
refer to Docket No. EPA-HQ-OAR-2005-
0474). You can access the rule and related
documents on EPA's Office of Transporta-
tion and Air Quality (OTAQ) Web site at:
www. epa. gov/otaq/highway-diesel/
index.htm
For More Information
For more information on this direct final
rule, please contact the Assessment and
Standards Division at:
U.S. Environmental Protection Agency
OTAQ
2000 Traverwood Drive
Ann Arbor, MI 48105
Voice-mail: (734) 214-4636
E-mail: asdinfo@epa.gov
Additional Provisions
This rule also includes changes to EPA's
regulations which:
• codify existing Agency policy
• update certification fee
regulations
• update OBD regulation
references
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