Control of Emissions of Air Pollution From 2004 and Later Model Year Heavy-Duty Highway Engines and Vehicles; Revision of Light-Duty Truck Definition
Federal RegisterOct 29, 1999
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SUMMARY: We are proposing to take several actions relating to emission
standards and test procedures for heavy-duty engines and vehicles
intended for operation on roads and highways. The proposed provisions
are for the 2004 and later model years. First, we are proposing new
more stringent emissions standards and related provisions for all
heavy-duty Otto-cycle (e.g., gasoline-fueled) engines and vehicles.
Vehicles in this category include large full size pick-up trucks, full
size cargo and passenger vans, and the largest sport utility vehicles.
For heavy-duty Otto-cycle engines and vehicles, today's proposal would
reduce the standards for oxides of nitrogen and hydrocarbons by
approximately 75 percent from current standards. Second, we propose to
reaffirm that the NMHC+NOX standard promulgated in October,
1997 for diesel heavy-duty engines is both necessary and feasible. This
standard represents about a 50 percent reduction in emissions of
nitrogen oxides, as well as reductions in hydrocarbons, from diesel
trucks and buses. Third, we are proposing to require on-board
diagnostics systems for all heavy-duty vehicles and engines at or below
14,000 lbs gross vehicle weight rating (GVWR), and to revise the on-
board diagnostics requirements for diesel light-duty vehicles and
trucks. These systems will identify the failure of components of the
emissions control system. Fourth, we are proposing the addition of new
test procedures and associated standards for heavy-duty diesel engines
and vehicles. Fifth, we are proposing to include heavy models of
gasoline and diesel-fueled sport-utility vehicles and similar heavy-
duty vehicles used primarily for personal transportation in the Tier 2
program that EPA proposed earlier this year. Today's proposal would
result in lower emissions of oxides of nitrogen and hydrocarbons, as
well as lower particulate matter due to reductions in secondary
particulate formation (secondary particulate matter is not emitted
directly from the engine, but is formed when emissions of oxides of
nitrogen react with ammonia in the atmosphere to produce ammonium
nitrate particulates), and would assist states and regions facing ozone
air quality problems that are causing a range of adverse health
effects, particularly respiratory impairment and related illnesses.
DATES: We must receive your comments on this NPRM by December 2, 1999.
A public hearing will be held on November 2, 1999 (EPA has published
notice of this hearing on October 22, 1999 (64 FR 56985).). EPA
requests that parties who want to testify notify the contact person
listed in the ADDRESSES section of this document one week before the
date of the hearing. More information about commenting on this action
and on the public hearing may be found in section XI What are the
Opportunities for Public Participation?
ADDRESSES: Written comments should be submitted (in duplicate, if
possible) to: EPA Air and Radiation Docket, Attn: Docket No. A-98-32,
Room M-1500 (Mail Code 6102), 401 M Street SW, Washington, DC 20460.
EPA requests that a copy of the comments also be sent to the contact
person listed below. Materials relevant to this proposal have been
placed in Docket Nos. A-98-32 and A-95-27 and may be viewed in Room M-
1500 between 8:00 a.m. and 5:30 p.m., Monday through Friday. The
telephone number is (202) 260-7548 and the facsimile number is (202)
260-4400. A reasonable fee may be charged by EPA for copying docket
materials.
The public hearing will be held at Top of the Tower, 1717 Arch
Street, 51st Floor, Philadelphia, PA 19103, telephone: 215-567-8787,
fax: 215-557-5171.
FOR FURTHER INFORMATION CONTACT: Margaret Borushko, U.S. Environmental
Protection Agency, Engine Programs and Compliance Division, 2000
Traverwood Drive, Ann Arbor, MI 48105-2498. Telephone (734) 214-4334;
Fax (734) 214-4816; e-mail [email protected].
SUPPLEMENTARY INFORMATION:
Regulated Entities
Entities potentially regulated by this action are those that
manufacture and sell new heavy-duty motor vehicles, new heavy-duty
engines, and new diesel light-duty motor vehicles in the United States.
Regulated categories and entities include:
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Category Examples of regulated entities
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Industry............................... Manufacturers of new heavy-duty
motor vehicles and engines.
Manufacturers of new diesel
light-duty motor vehicles and
engines.
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This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in the table could also be regulated. To determine whether
your activities are regulated by this action, you should carefully
examine the applicability criteria in Secs. 86.001-1 and 86.1801-01. If
you have questions regarding the applicability of this action to a
particular entity, consult the person listed in the preceding FOR
FURTHER INFORMATION CONTACT section.
Obtaining Rulemaking Documents Through the Internet
The preamble, regulatory language, regulatory impact analysis, and
other related documents are also available electronically from the EPA
Internet Web site. This service is free of charge, except for any cost
you already incur for Internet connectivity. The electronic version is
made available on the day of publication on the primary Web site listed
below. The EPA Office of Mobile Sources also publishes Federal Register
notices and related documents on the secondary Web site listed below.
1. http://www.epa.gov/docs/fedrgstr/EPA-AIR/ (either select desired
date or use Search feature)
2. http://www.epa.gov/OMSWWW/ (Look in What's New or under the specific
rulemaking topic)
Please note that due to differences between the software used to
develop the document and the software into which the document may be
downloaded, changes in format, page length, etc. may occur.
Table of Acronyms and Abbreviations
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ABT Averaging, Banking, and Trading
AECD Auxiliary Emission Control Device
ALVW Adjusted Loaded Vehicle Weight
ANPRM Advance Notice of Proposed Rulemaking
BSFC Brake-Specific Fuel Consumption
CAA Clean Air Act
CAP 2000 Compliance Assurance Program for the 2000 and
later model years
CARB California Air Resources Board
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CASAC Clean Air Scientific Advisory Committee
CFF Clean Fuel Fleet
CO Carbon Monoxide
DF Deterioration Factor
DOC Diesel Oxidation Catalyst
DRI Desert Research Institute
EGR Exhaust Gas Recirculation
EMA Engine Manufacturers Association
EPA Environmental Protection Agency
FEL Family Emission Limit
g/bhp-hr grams per brake-horsepower hour
g/mi grams per mile
GVWR Gross Vehicle Weight Rating
HC Hydrocarbons
HD Heavy-Duty
HDDE Heavy-Duty Diesel Engine
HDE Heavy-Duty Engine
HDEWG Heavy-Duty Engine Working Group
HDV Heavy-Duty Vehicle
HEUI Hydraulically Actuated Electronic Unit
Injection
HLDT Heavy Light-Duty Truck
LDT Light-Duty Truck
LDV Light-Duty Vehicle
LEV Low Emission Vehicle
LLDT Light Light-Duty Truck
LRT Load Response Test
MDV Medium-Duty Vehicle
MEUI Mechanically Actuated Electronic Unit Injection
MIL Malfunction Indicator Light
MY Model Year
NAAQS National Ambient Air Quality Standards
NCP Non-Conformance Penalty
NMHC Non-Methane Hydrocarbon
NMOG Non-Methane Organic Gas
NOX Nitrogen Oxides
NPRM Notice of Proposed Rulemaking
OBD On-Board Diagnostics
OEM Original Equipment Manufacturer
ORVR Onboard Refueling Vapor Recovery
PM Particulate Matter
PM10 Particulate Matter of 10 microns or less in
diameter
PM2.5 Particulate Matter of 2.5 microns or less in
diameter
RIA Regulatory Impact Analysis
SIP State Implementation Plan
SOP Statement of Principles
TW Test Weight
UDDS Urban Dynamometer Driving Schedule
ULEV Ultra Low Emission Vehicle
VGT Variable Geometry Turbocharger
VMT Vehicle Miles Traveled
VNT Variable Nozzle Turbocharger
VOC Volatile Organic Compound
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Table of Contents
I. What is EPA Proposing to Do?
A. Changes to the Engine-Based Program
B. Expanding the Otto-cycle Vehicle-based Program to Certain Heavy-
duty Vehicles
C. Additional Changes Affecting Heavy-duty Vehicle and Heavy-duty
Engine Programs
D. Heavy-duty Lead Time Issues and Voluntary Federal Standards
II. What is the Environmental Need for this Proposal?
A. Need for Additional NOX and NMHC Reductions
1. Health and Welfare Effects from NMHC and NOX
2. Current Compliance with the Ozone NAAQS
3. Future Compliance with the Ozone NAAQS
4. Contribution of HD Diesel and Gasoline Engines to Total VOC
and NOX Inventories
B. Need for Additional PM Reductions
1. Health and Welfare Effects from PM
2. Current and Future Compliance with the PM10 NAAQS
3. Contribution of HD Diesel and Gasoline Vehicles to PM
Inventories
a. Contribution to National PM10 Inventories
b. Source-apportionment Studies for Diesel PM
C. Air Toxics from HD Engines and Vehicles
III. What is the Important Background Information for this Proposal?
A. Statement of Principles and Rulemaking History
B. 1999 Review of Heavy-duty Diesel Engine NMHC+NOX
Standards
C. Proposal for Heavy-duty Gasoline Engine Standards
1. Summary of Comments on 1996 NPRM
2. Analysis Leading to Decision to not Finalize Otto-cycle
Standards
D. Consent Decrees with Heavy-duty Diesel Engine Manufacturers
IV. What are the Details of this Proposal?
A. Reaffirmation of 2004 NMHC + NOX Standard for Heavy-
duty Diesel Engines
B. Are Changes in Diesel Fuel Quality Necessary to Meet the 2004
Standards?
C. Otto-cycle Engine-based Program
1. Engine Exhaust Emissions Standards
2. Averaging, Banking, and Trading for Otto-Cycle Engines
D. Supplemental Exhaust Emission Standards and Test Procedures for
HD Diesel Engines
1. Introduction/Background
2. Proposed Supplemental Test Procedures and Standards
a. Supplemental Steady-State Test
b. Not-To-Exceed Limits
c. Diesel Supplemental Load Response Test
d. Ambient Conditions, Temperature and Humidity, Laboratory and
In-use Testing
3. Access to On-board Computer Information
E. Otto-cycle Vehicle-based Program
1. Moving to a Vehicle-based Test Procedure and Standards
2. Vehicle Exhaust Emissions Standards
3. Heavy-duty Vehicle Averaging, Banking and Trading
a. Background
b. Proposal
c. Credit exchanges between the engine and chassis-based
programs
4. Evaporative standards/onboard refueling vapor recovery
a. Enhanced evaporative emissions
b. Onboard refueling vapor recovery
5. Compliance Assurance Program
a. CAP 2000 for HDVs
b. Proposed Modifications to the CAP 2000 Program For Chassis-
Based HDVs
6. Useful Life
7. Aftermarket Alternative Fuels Conversions
F. Proposal to Revise the Definition of Light-duty Truck
1. Background
2. Proposal
3. Integration into Proposed Tier 2 Program
a. Tier 2 Standards for New HLDTs
b. Interim Standards for New HLDTs
c. Technological Feasibility of Tier 2 Standards for New HLDTs
G. On-Board Diagnostics
1. Background on OBD
2. CARB OBDII Requirements
3. Proposed Federal OBD Requirements
4. Federal OBD Malfunction Thresholds and Monitoring
Requirements
5. Proposed Standardization Requirements
6. Deficiency Provisions
7. Applicability and Waivers
8. Certification Provisions
H. Durability Procedures
I. Non-Conformance Penalties
V. Additional Heavy-Duty Engine Provisions Under Consideration
A. Revision to the Definition of Rated Speed
B. A Manufacturer-based In-use Testing Program for Heavy-duty
Engines
C. On-board Diagnostics for Heavy-duty Engines and Vehicles Above
14,000 Pounds GVWR
D. Applying the Not-to-Exceed Approach and Emission Limits to Heavy-
duty Otto-cycle Engines
VI. Are the Proposed Requirements Technologically Feasible?
A. 2004 Emission Standards for Heavy-duty Diesel Engines
1. Probable Emission Control Strategies
2. Feasibility of 2004 HD Diesel Standards
B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and
Engines
1. Current Technologies
2. Chassis-based standards
3. Engine-based standards
4. Onboard Refueling Vapor Recovery
C. On-Board Diagnostics
VII. What are the Environmental Benefits of this Proposal?
A. 2004 Emission Standards for Heavy-Duty Diesel Engines
B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and
Engines
C. Benefits of the Supplemental Standards and In-Use Control
Measures of Today's Proposal
VIII. What are the Economic Impacts of the Proposal?
A. 2004 Emission Standards for Heavy-duty Diesel Engines
1. Expected Technologies
2. Per Engine Costs
3. Aggregate Costs to Society
B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and
Engines
1. Expected Technologies
2. Per Vehicle Costs
3. Aggregate Cost to Society
[[Page 58474]]
IX. What is the Cost-Effectiveness of the Proposal?
A. 2004 Emission Standards for Heavy-duty Diesel Engines
B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and
Engines
X. Are Future Reductions in HD Emissions Possible?
A. Potential Future Standards for Heavy-duty Diesel Vehicles and
Engines
1. Potential Future Reductions in Heavy-duty Diesel
NOX and NMHC
2. Potential Future Reductions in Heavy-duty Diesel Engine PM
3. Potential Structure of Future Diesel Emission Standards
B. Potential Future Standards for Heavy-duty Otto-cycle Vehicles
1. Exhaust Emission Standards
2. Evaporative standards
XI. What are the Opportunities for Public Participation?
A. Comments and the Public Docket
B. Public Hearing
XII. What Administrative Requirements Apply to this Proposal?
A. Compliance with Executive Order 12866
B. Impact on Small Entities
C. Unfunded Mandates Reform Act
D. Reporting and Recordkeeping Requirements
E. Compliance with Executive Order 13045
F. Enhancing Intergovernmental Partnerships
G. Consultation and Coordination with Indian Tribal Governments
H. National Technology Transfer and Advancement Act
I. Compliance with Executive Order on Federalism
XIII. What is EPA's Statutory Authority for this Proposal?
I. What Is EPA Proposing To Do?
EPA (or, ``the Agency'') is proposing to take several actions
relating to emission standards and test procedures for heavy-duty
engines (HDEs) and heavy-duty vehicles (HDVs) intended for highway
operation.\1\ The proposed provisions would become effective starting
with the 2004 model year (MY). These actions supplement a June 1996
proposed rule (61 FR 33421, June 27, 1996), in which we proposed new
emission standards for heavy-duty diesel engines (HDDE) and heavy-duty
Otto-cycle engines and vehicles, and a subsequent October 1997 final
rule (62 FR 54694, October 21, 1997), in which we finalized new
emission standards for heavy-duty diesel engines.\2\
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\1\ Light-duty vehicles and light-duty trucks are defined as
vehicles with a gross vehicle weight rating (GVWR) below 8,500
pounds. Heavy-duty vehicles are vehicles with a GVWR greater than or
equal to 8,500 pounds. Heavy-duty engines are engines used in heavy-
duty vehicles.
\2\ The terms ``diesel'' and ``Otto-cycle'' generally refer to
the type of combustion cycle employed by an engine. In a diesel-
cycle engine combustion is brought about by the compression of the
fuel mixture (compression ignition), whereas in an Otto-cycle engine
combustion is achieved by providing a spark to the fuel mixture
(spark ignition). Although a generalization for which there are
exceptions, diesel-cycle vehicles are generally fueled with diesel
fuel and Otto-cycle vehicles are generally fueled with standard
gasoline.
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Currently, EPA has a chassis-based regulatory program for light-
duty vehicles (LDVs) and light-duty trucks (LDTs), meaning that the
vehicle itself is subject to emission standards and testing. For all
heavy-duty vehicles the engine alone is tested and must currently meet
engine-based standards.\3\ Engine testing currently applies to all
diesel-cycle and Otto-cycle heavy-duty vehicles. One of the key
elements of today's action is a proposal to begin regulating a subset
of heavy-duty vehicles using chassis-based requirements. The heavy-duty
vehicles that are proposed to be subject to chassis-based requirements
are complete Otto-cycle heavy-duty vehicles with a gross vehicle weight
rating (GVWR) below 14,000 pounds.4,5 In addition, some
complete gasoline and diesel-fueled heavy-duty vehicles between 8,500
and 10,000 pounds GVWR are proposed to be incorporated into the Tier 2
program proposed by EPA earlier this year (64 FR 26004, May 13, 1999).
Today's proposal can generally be separated into those elements
relating to the new chassis-based requirements and those elements that
affect the engine-based requirements. The proposals listed below are
explained in greater detail in the remainder of this document.
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\3\ Engine-based standards are expressed in terms of emissions
per unit of work, whereas chassis-based (or vehicle-based) standards
are expressed in terms of amount of emissions per mile driven by the
vehicle.
\4\ ``Complete'' vehicles are those that are manufactured with
their primary cargo carrying container or device attached, whereas
``incomplete'' vehicles are those that are manufactured without the
primary cargo carrying container or device attached. Incomplete
vehicles (basically the engine plus a chassis) are then manufactured
into a variety of vehicles, such as recreational vehicles, panel
trucks, dump trucks, fire trucks, and tow trucks.
\5\ Gross Vehicle Weight Rating (GVWR) is defined by federal
regulation in 40 CFR 86.082-2 as ``The value specified by the
manufacturer as the maximum design loaded weight of a single
vehicle.'' In other words, it is the weight of the vehicle
completely loaded with the maximum load that the manufacturer states
the vehicle is capable of carrying.
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Some of these proposals would harmonize EPA's regulatory programs
with California's current medium-duty vehicle (MDV) program (e.g.,
vehicle-based standards for complete Otto-cycle heavy-duty vehicles
below 14,000 pounds GVWR), while others may differ from California's
current requirements. These similarities and differences are outlined
in the detailed discussion that follows. We request comments on the
proposals described below, and encourage commenters to supply relevant
data that would help us further assess the proposals.6
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\6\ The current federal standards for Clean Fuel Vehicles are
less stringent than the proposed Otto-cycle standards and the
existing diesel standards for the 2004 and later model years. See 40
CFR 88.105-94. The 2004 and later model year standards proposed
today would supercede the current Clean Fuel Vehicle standards, and,
if EPA adopts the Otto-cycle standards proposed today and maintains
the diesel standards for the 2004 and later model years, the Agency
intends to undertake a rulemaking to revise the Clean Fuel Vehicle
standards accordingly.
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A. Changes to the Engine-Based Program
The first sections of this proposal describe the proposed revisions
to the engine-based program. Some of these proposals would apply to
both diesel and Otto-cycle engines, and others would apply uniquely to
either diesel or Otto-cycle engines. Proposed requirements that affect
the engine-based program include:
Reaffirmation of the existing 2004 and later model year
NMHC+NOx standard for heavy-duty diesel engines.
New more stringent emission standards for 2004 and later
model year Otto-cycle heavy-duty engines.
A revised averaging, banking, and trading (ABT) program
for Otto-cycle heavy-duty engines.
Revised deterioration factor (DF) requirements for heavy-
duty engines.
New emission standards for heavy-duty diesel engines to
improve the assurance that vehicles are emitting low levels of
pollutants over a wide range of operation experienced in actual use.
New supplemental test procedures for heavy-duty diesel
engines associated with the proposed new emission
standards.7
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\7\ We believe that our compliance program is fundamentally
incomplete until a similar form of additional assurance that Otto-
cycle engines will meet applicable emission standards in-use can be
added to the compliance requirements, but such provisions are not
specifically proposed today. Section V of today's proposal describes
several important compliance program elements that are not included
in today's proposal, but that we intend to finalize such that they
can take effect in conjunction with those elements in today's
proposal. See section V for more information.
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B. Expanding the Otto-Cycle Vehicle-Based Program to Certain Heavy-Duty
Vehicles
Additional sections of this proposal describe the proposed chassis-
based (or vehicle-based) program for certain heavy-duty vehicles. Many
of these proposals result in harmonization with the California Air
Resources Board (CARB) Medium-duty Vehicle (MDV)
[[Page 58475]]
Program. For the vehicle-based program, we are proposing the following
elements:
New standards for 2004 and later model year complete Otto-
cycle heavy-duty vehicles with a GVWR below 14,000 pounds.
The incorporation of certain complete Otto-cycle and
diesel vehicles between 8,500 and 10,000 pounds GVWR into the Tier 2
light-duty program. These provisions would be limited to those vehicles
designed primarily for personal transportation.
Vehicle-based testing of all complete heavy-duty Otto-
cycle vehicles below 14,000 pounds GVWR for these new standards.
An averaging, banking, and trading program.
On-board refueling vapor recovery (ORVR) requirements.
CAP 2000 provisions.8
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\8\ The new compliance assurance program for light-duty vehicles
and light-duty trucks, known as CAP 2000 (since manufacturers may
opt-in for model year 2000), streamlines the existing vehicle
certification program, enabling manufacturers to save significant
time and money. In addition, it requires manufacturers to test
customer-owned in-use vehicles for model year 2001 and beyond. The
CAP 2000 program was proposed on July 23, 1998 (63 FR 36954), and
finalized on May 4, 1999 (64 FR 23906).
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Revised useful life requirements.
C. Additional Changes Affecting Heavy-Duty Vehicle and Heavy-Duty
Engine Programs
Additional sections describe provisions or issues that apply to
both heavy-duty vehicle and engine programs. These proposals include:
On-board Diagnostics (OBD) requirements for heavy-duty
diesel and Otto-cycle vehicles and engines up to 14,000 pounds GVWR.
Non-Conformance Penalties (NCPs).
D. Heavy-Duty Lead Time Issues and Voluntary Federal Standards
One of the important concepts contained in the rulemaking record,
is the need for harmonized, 50-state emission standards for the heavy-
duty industry. Consistent national standards provide the states with
the emission reductions they need, while providing manufacturers with
the knowledge they can design and market one engine design regardless
of what state the engine is sold to. Our proposal today would implement
nationwide standards which would harmonize with California for the
majority HD engines and vehicle in 2004 ( the exception being
incomplete HD Otto-cycle engines.)
Since the finalization of the 1997 rule for 2004 HD diesels, state
and local air quality agencies have been counting on the emission
reductions from the 2004 standards in order to meet their long-term air
quality needs. In addition, as discussed previously in this proposal,
the 2004 standards for HD Otto-cycle engines and vehicles will also
provide state and local air quality agencies additional needed emission
reductions. However, Section 202 of the Clean Air Act requires EPA to
provide manufacturers of heavy-duty engines and vehicles four years of
lead time between standards. This would require EPA to issue a final
rule by the end of 1999 in order to implement new standards in 2004. We
are concerned due to the short amount of time between today's proposal
and the end of the calendar year that the final rule for today's
proposal may not be final until after December 31, 1999, which may
prevent a model year 2004 implementation of the standards proposed
today. This concern does not apply for the 2004 model year heavy-duty
diesel engine standards which were promulgated in 1997 and meet the
lead time requirements.
This four year lead time issue for the 2004 standards contained in
today's proposal reflects a statutory requirement, not a technological
feasibility issue. As demonstrated elsewhere in this proposal,
technology is clearly available which will allow manufacturers to meet
the proposed HD diesel and HD gasoline standards by 2004.
The lack of more stringent federal 49-state HD standards in 2004
may lead some states with incentive to exercise their rights under
Section 177 of the Clean Air Act to adopt the California HD diesel and
Otto-cycle standards in order to realize the emission reductions
associated with covering vehicles produced in 2004. This could result
in a patchwork of emission standards across the country and could
present the manufacturers with significant difficulties.
In the event the Agency is unable to finalize the new standards
contained in today's proposal by the end of calendar year 1999, we
request comment on the appropriateness of EPA's efforts to manage the
implementation of these standards and in particular, of establishing a
program for those manufacturers willing to cooperate in meeting the
requirements in today's proposal. We would expect that manufacturers
participating in this program would merely certify their 2004 model
year engines to meet all of the emission standards and requirements
included in today's proposal. If the proposed standards are not
finalized by the end of 1999, mandatory federal standards would apply
in model year 2005, with the goal of putting in place all requirements
contained in today's proposal. We request comment on whether
manufacturers would need to opt-in to such a program, and how such opt-
in would take place. In addition, EPA requests comment on incentives to
encourage manufacturers to opt into the voluntary program.
II. What Is the Environmental Need for This Proposal?
This section presents information on the negative health and
environmental impacts from air pollution from heavy-duty (HD) engines
and vehicles, as well as EPA's assessment of the need for additional
emission reductions from HD engines and vehicles in order to meet the
air quality needs of the U.S. A detailed analysis and explanation of
the health impacts and air quality needs was presented in the advanced
notice of proposed rulemaking, as well as the preamble and the
Regulatory Impact Analysis (RIA) for the proposal and final rule of the
1997 rulemaking for the 2004 standards.9 The reader should
refer to those documents for additional information on this topic.
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\9\ See ``Control of Air Pollution for Heavy-Duty Engines,
Advanced Notice of Proposed Rulemaking'', Available in EPA Air
Docket A-95-27, Docket Item # AMS-FRL, and ``Draft Regulatory Impact
Analysis: Control of Emissions of Air Pollution from Highway Heavy-
Duty Engines'', available in EPA Air Docket A-95-27, Docket Item #
III-B-01, and ``Control of Emissions of Air Pollution from Highway
Heavy-Duty Engines; Notice of Proposed Rulemaking'' available in EPA
Air Docket A-95-27, Docket Item # III-A-01, and ``Final Regulatory
Impact Analysis: Control of Emissions of Air Pollution from Highway
Heavy-Duty Engines'', available in EPA Air Docket A-95-27, Docket
Item # V-B-01, and ``Control of Emissions of Air Pollution from
Highway Heavy-Duty Engines; Final Rule,'' available in EPA Air
Docket A-95-27, Docket Item # V-A-01.
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A. Need for Additional NOx and NMHC Reductions
1. Health and Welfare Effects From NMHC and NOx
Oxides of Nitrogen (NOx) and volatile organic compounds
(VOC) are precursors in the photochemical reaction which forms
tropospheric ozone. VOC emissions from mobile sources consist mostly of
nonmethane hydrocarbons (NMHC). There is a large body of evidence
showing that ozone can cause harmful respiratory effects including
chest pain, coughing, and shortness of breath, affecting people with
compromised respiratory systems and children most severely. In
addition, NOx itself can directly harm human health. Beyond
their human health effects, other negative environmental effects are
also associated with ozone
[[Page 58476]]
and NOx. Ozone has been shown to injure plants and
materials; NOx contributes to the secondary formation of
particulate matter (PM) (nitrates), acid deposition, and the overgrowth
of algae in coastal estuaries. These environmental effects, as well as
the health effects noted above, are described in the Regulatory Impact
Analysis, and additional information may be found in EPA's ``staff
papers'' and ``air quality criteria'' documents for ozone and nitrogen
oxides.10, 11, 12, 13
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\10\ U.S. EPA, 1996, Review of National Ambient Air Quality
Standards for Ozone, Assessment of Scientific and Technical
Information, OAQPS Staff Paper, EPA-452/R-96-007.
\11\ U.S.EPA, 1996, Air Quality Criteria for Ozone and Related
Photochemical Oxidants, EPA/600/P-93/004aF.
\12\ U.S. EPA, 1995, Review of National Ambient Air Quality
Standards for Nitrogen Dioxide, Assessment of Scientific and
Technical Information, OAQPS Staff Paper, EPA-452/R-95-005.
\13\ U.S.EPA, 1993, Air Quality Criteria for Oxides of Nitrogen,
EPA/600/8-91/049aF.
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2. Current Compliance With the Ozone NAAQS
Today, many states are finding it difficult to show how they can
meet or maintain compliance with the current National Ambient Air
Quality Standard (NAAQS) for ozone by the deadlines established in the
Clean Air Act (CAA, or ``the Act'').14 As of August, 1998,
72 million people outside of California lived in 36 metropolitan areas
and two counties designated nonattainment under the 1-hour ozone NAAQS.
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\14\ See 42 U.S.C. 7401 et seq.
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In July 1997, EPA established a new 8-hour ozone NAAQS to better
protect against longer exposure periods at lower concentrations than
the current 1-hour standard. Under the July 1997 rule, the 1-hour NAAQS
would still be applicable in certain areas during the transition to the
8-hour standard (62 FR 38856; July 17, 1997). EPA reviewed ambient
ozone monitoring data for the period 1993 through 1995 to determine
which counties violated either the 1-hour or 8-hour NAAQS for ozone
during this time period.15, 16 Eighty-four counties violated
the 1-hour NAAQS during this 3-year period, while 248 counties violated
the 8-hour NAAQS. The 84 counties had a 1990 population of 47 million,
while the 248 counties had a 1990 population of 83 million. EPA is
reviewing more recent air quality data for 1996 and 1997. A preliminary
assessment of 1994 through 1996 ozone monitoring data reveals only
marginal changes in the number of counties experiencing a nonattainment
problem with the 8-hour NAAQS, and essentially no change in the
population levels impacted by nonattainment.
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\15\ This use of the term ``nonattainment'' in reference to a
specific area is not meant as an official designation or future
determination as to the attainment status of the area.
\16\ See 63 FR 57356, October 27, 1998, ``Finding of Significant
Contribution and Rulemaking for Certain States in the Ozone
Transport Assessment Group Region for Purposes of Reducing Regional
Transport of Ozone.''
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On May 14, 1999, a panel of the U.S. Court of Appeals for the
District of Columbia Circuit found, by a 2-1 vote, that Clean Air Act
sections 108 and 109, as interpreted by EPA in establishing the 8-hour
ozone NAAQS (as well as the new NAAQS for PM2.5 and
PM10), effect an unconstitutional delegation of
Congressional power. American Trucking Ass'ns, Inc., et al., v.
Environmental Protection Agency, Nos. 97-1440, 1441 (D.C. Cir. May 14,
1999). The Court remanded the record to EPA. One judge dissented,
finding that the majority's opinion ``ignores the last half-century of
Supreme Court nondelegation jurisprudence.'' Id., slip op. at 31. The
Court also ruled, regarding the 8-hour ozone NAAQS, that the statute
permits EPA to promulgate a revised ozone NAAQS and to designate the
attainment status of areas. However, the Court curtailed EPA's ability
to require states to comply with the revised ozone NAAQS. Further the
Court directed the Agency to determine whether tropospheric ozone has a
beneficent effect, and if so, assess ozone's net adverse health effect.
In general, the Court did not find fault with the scientific basis for
EPA's determinations regarding adverse health effects from ozone. On
June 28, 1999, EPA filed a petition for rehearing and petition for
rehearing en banc seeking review of the panel's decision.
The Court's decision does not address the provisions of section
202(a), and does not change EPA's belief that the standards in today's
proposal are lawful and appropriate under these criteria. We believe
that the information provided in this proposal and the draft Regulatory
Impact Analysis, as well as the information that EPA relied on in
setting the NAAQS for ozone, support a conclusion that ozone can be
reasonably anticipated to endanger the public health or welfare. EPA's
belief that it is appropriate to seek reductions of NOX and
NMHCs from heavy duty vehicles and engines to protect public health or
welfare is not changed by the decision of the court.
3. Future Compliance With the Ozone NAAQS
Local, state and federal organizations charged with delivering
cleaner air have mounted significant efforts in recent years to reduce
air quality problems associated with ground-level ozone, and there are
signs of partial success. NOX and VOCs appear to have been
reduced, and average levels of ozone seem to have begun gradually
decreasing. However, this progress is in jeopardy. EPA projects that
reductions in ozone precursors that will result from the full
implementation of current emission control programs will fall far short
of what would be needed to offset the normal emission increases that
accompany economic expansion. By the middle of the next decade, the
Agency expects that the downward trends will have reversed, primarily
due to increasing numbers of emission sources. By around 2020, EPA
expects that NOX levels will have returned to current levels
in the absence of significant new reductions.17 To the
extent that some areas are seeing a gradual decrease in ozone levels in
recent years, EPA believes that the expected increase in NOX
will likely result in an increase in ozone problems in the future.
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\17\ See Chapter 2 of the draft Regulatory Impact Analysis for
this proposal.
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The Agency has recently finalized a rulemaking requiring 22 States
and the District of Columbia to submit State Implementation Plan (SIP)
revisions to reduce specified amounts of emissions of NOX
for the purpose of reducing NOX and ozone transport across
State boundaries in the eastern half of the United States.18
The specified NOX reduction for each State varies. In making
this decision EPA relied upon, among other items, ozone modeling
studies for the eastern U.S. In the baseline scenario for these
modeling runs EPA included the emission reductions expected from the
2004 HDDE standards. These modeling runs concluded that significant
additional NOX reductions beyond the baseline case were
necessary from 22 eastern States in order to meet the ozone NAAQS
standards. The NOX emission reductions from the 2004 HDDE
standards are assumed by these models to be part of the reductions that
will be needed to meet the ozone NAAQS in these areas. The Agency did
not analyze the specified reductions that would be required by the rule
if the baseline did not include the 2004 HDDE standards.
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\18\ See 63 FR 57356, October 27, 1998, ``Finding of Significant
Contribution and Rulemaking for Certain States in the Ozone
Transport Assessment Group Region for Purposes of Reducing Regional
Transport of Ozone.''
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The deadline for submission of SIPs was recently stayed by a panel
of the Court of Appeals for the D.C. Circuit pending further review.
EPA believes that the October 27, 1998 rule is fully consistent with
the Clean Air Act and
[[Page 58477]]
should be upheld. However, it should be noted that if the emission
reductions sought by the SIP call are not achieved, it would be more
difficult to attain the NAAQS for ozone.
In addition, many states (including western states) have also
included the emission reductions projected from the 2004 HDDE standards
in their State Implementation Plans. This demonstrates that these
states are relying on these emission reductions to meet the ozone
NAAQS.
4. Contribution of HD Diesel and Gasoline Engines to Total VOC and
NOX Inventories
HD engines and vehicles are important contributors to the national
inventories of NOX emissions, and they contribute moderately
to national VOC pollution. The draft RIA for this proposal describes in
detail recent emission inventory modeling completed by EPA for this
proposal. Table 1 summarizes EPA's current estimates for national
NOX and VOC contributions from major source categories.
Table 1.--2000 National NOX and VOC Emissions
[thousand short tons per year]
----------------------------------------------------------------------------------------------------------------
Emission source NOX NOX % VOC VOC %
----------------------------------------------------------------------------------------------------------------
Light-Duty Vehicles......................................... 4,420 19 4,098 25
Heavy-Duty Diesel Vehicles.................................. 2,274 10 246 1
Heavy-Duty Gasoline Vehicles................................ 318 1 198 1
Nonroad Engines and Vehicles................................ 5,343 23 2,485 15
Other (Stationary Point and Area Sources)................... 10,656 47 9,567 58
---------------------------------------------------
Total Nationwide Emissions.......................... 22,831 ........... 16,594 ...........
----------------------------------------------------------------------------------------------------------------
It should be noted that Table 1 does not include estimated
NOX emission impacts associated with the previously produced
HD diesel engines at issue in the recent enforcement action involving
the government and several HD diesel engine manufacturers. The
relationship of these consent decrees to today's proposed rule is
described in section III.D. The excess NOX emissions from
these engines are substantial, and would significantly increase the
estimated contribution from HD diesel vehicles presented in Table 1.
However, as discussed in section VI.A of this preamble, we did not
update our emission inventory model to include the impact on these
previously produced engines for this proposal.
Notwithstanding these excess emissions, Table 1 indicates that HD
gasoline and diesel vehicles will represent approximately 11 percent of
national NOX emissions and two percent of national VOC
emissions in the year 2000. The Regulatory Impact Analysis document for
this proposal contains updated emission inventory modeling for HD
vehicles. The results show that without additional HD NOX
control beyond the 1998 standards, national NOX emissions
from HD vehicles would decline between 2000 and 2005, but this trend
would stop in 2005. After 2005, NOX emissions from the HD
vehicle fleet would increase as a result of future growth in the HD
vehicle market without additional emission controls. A similar trend is
seen for national NMHC emissions from HD vehicles; however, NMHC
emissions are projected to decrease until approximately 2010, after
which changes in the make-up of the fleet result in an increase in the
NMHC emissions from HD vehicles (see Chapter 5 of the draft RIA).
We estimate that the HD diesel and gasoline standards contained in
this proposal will result in a combined reduction by the year 2020 of
1,629,000 tons of NOX per year and 54,000 tons of
hydrocarbons (HC) per year. Section VI of this preamble (``What are the
Environmental Benefits of this Proposal?'') as well as the draft RIA
for this proposal contain more detailed information on the Agency's
projected benefits from today's proposal.
B. Need for Additional PM Reductions
1. Health and Welfare Effects From PM
Particulate matter is the general term for the mixture of solid
particles and liquid droplets found in the air. Particulate matter
includes dust, dirt, soot, smoke, and liquid droplets that are directly
emitted into the air from natural and manmade sources, such as
windblown dust, motor vehicles, construction sites, factories, and
fires. Particles are also formed in the atmosphere by condensation or
the transformation of emitted gases such as sulfur dioxide, nitrogen
oxides, and volatile organic compounds. Particulate matter, like ozone,
has been linked to a range of serious respiratory health problems.
Scientific studies suggest a likely causal role of ambient particulate
matter in contributing to a series of health effects. The key health
effects categories associated with particulate matter include premature
mortality, aggravation of respiratory and cardiovascular disease (as
indicated by increased hospital admissions and emergency room visits,
school absences, work loss days, and restricted activity days), changes
in lung function and increased respiratory symptoms, changes to lung
tissues and structure, and altered respiratory defense mechanisms. PM
also causes damage to materials and soiling. It is a major cause of
substantial visibility impairment in many parts of the U.S.
Motor vehicle particle emissions and the particles formed by the
transformation of motor vehicle gaseous emissions (secondary
particulates) tend to be in the fine particle range. Fine particles
(those less than 2.5 micrometers in diameter) are a health concern
because they easily reach the deepest recesses of the lungs. Scientific
studies have linked fine particles (alone or in combination with other
air pollutants), with a series of significant health problems,
including premature death; respiratory related hospital admissions and
emergency room visits; aggravated asthma; acute respiratory symptoms,
including aggravated coughing and difficult or painful breathing;
chronic bronchitis; and decreased lung function that can be experienced
as shortness of breath.
These effects are discussed further in the RIA for this proposal,
as well as the RIA for the 1997 final rule for the 2004 standards, and
additional information may be found in EPA's ``staff paper'' and ``air
quality criteria document'' for particulate matter.19
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\19\ U.S. EPA, 1996, Air Quality Criteria for Particulate
Matter, EPA/600/P-95/001aF.
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2. Current and Future Compliance With the PM10 NAAQS
The first NAAQS for particulate matter regulated total suspended
[[Page 58478]]
particulate in the atmosphere. In 1987, EPA replaced that standard with
one for inhalable PM (PM10--particles less than ten microns
in size), because the smaller particles, due to their ability to reach
the lower regions of the respiratory tract, are more likely responsible
for the adverse health effects. The major source of PM10 is
fugitive emissions from agricultural tilling, construction, fires, and
unpaved roads. Some revisions to the PM10 standards were
made in 1997. EPA has also recently added new fine particle standards
for particles less than 2.5 microns in size (PM2.5). Most of
the particulate due to motor vehicles falls in the fine particle
category. These standards have both an annual and a daily component.
The annual component is set to protect against long-term exposures,
while the daily component protects against more extreme short-term
events.
As noted above, on May 14, 1999, a panel of the U.S. Court of
Appeals for the District of Columbia Circuit found, by a 2-1 vote, that
Clean Air Act sections 108 and 109, as interpreted by EPA in
establishing the new NAAQS for PM2.5 and PM10,
effect an unconstitutional delegation of Congressional power. American
Trucking Ass'ns, Inc., et al., v. Environmental Protection Agency, Nos.
97-1440, 1441 (D.C. Cir. May 14, 1999). The Court remanded the record
to EPA. The court vacated the new PM10 standard, but has not
vacated the PM2.5 standard. See American Trucking Ass'ns,
Inc., et al., v. Environmental Protection Agency, No. 97-1440 (D.C.
Cir. June 18, 1999).
Compliance with the current PM10 standard continues to
be a problem. According to the 1996 EPA Air Quality and Emissions
Trends report, there were 7 million people living in 15 counties across
the U.S. which exceeded the PM10 NAAQS in 1996.20
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\20\ U.S. EPA, January 1998, ``National Air Quality and
Emissions Trends Report, 1996'', EPA 454/R-97-0013.
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EPA recently projected ambient PM10 levels and the
number of U.S. counties expected to be in violation of the revised
PM10 NAAQS in 2010.21 Based on the 1990 census,
about 10 million people live in the 11 counties projected to be in
nonattainment of the revised PM10 NAAQS.
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\21\ Regulatory Impact Analyses for the Particulate Matter and
Ozone National Ambient Air Quality Standards and Proposed Regional
Haze Rule, Innovative Strategies and Economics Group, Office of Air
Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, N.C., July 16, 1997.
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3. Contribution of HD Diesel and Gasoline Vehicles to PM Inventories
a. Contribution to National PM10 Inventories
The national inventory of PM10 is dominated by natural
sources (wind erosion) and so-called miscellaneous sources, which
include paved and unpaved road dust, agricultural crops, fugitive dust,
and dust from construction activities. Together natural and
miscellaneous sources represented approximately 90 percent of national
PM10 emissions in 1996. Since these sources are not readily
amenable to regulatory standards and controls, it is appropriate to
focus on more traditional ``controllable'' portions of the particulate
pollution problem when considering the need for PM controls. Excluding
natural and miscellaneous sources, HD vehicles (gasoline and diesel)
represent approximately five percent of the remaining man-made sources
of PM10 in 1996, virtually all (95 percent) of which is from
diesel vehicles.22
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\22\ U.S. EPA, December 1997, ``National Air Pollutant Emission
Trends, 1900-1996'', EPA-454/R-97-011.
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In the proposal for the 1997 final rule for the 2004 standards, EPA
presented data on future projections of mobile and stationary source
PM10 national emission inventories out to the year 2010, as
well as a break-down of mobile sources into on-highway light-duty, on-
highway heavy-duty, and nonroad categories (see 61 FR 33432-33440, June
27, 1996). These projections showed that without additional future
controls on PM or NOX emissions, annual PM emissions (tons/
year) for all mobile sources would begin to rise after the year 2000.
The Regulatory Impact Analysis document for this proposal presents the
results of updated emission modeling specifically for HD vehicles.
These results show that the annual national PM10 emissions
from HD vehicles (tons/year) are expected to decline between now and
approximately the year 2010, after which increases in the size of the
fleet will result in a steady increase into the future (see Chapter 5
of the draft RIA).
b. Source-apportionment Studies for Diesel PM
Discussion of PM inventories from HD vehicles, and in particular HD
diesel vehicles which represent the vast majority of the HD PM
emissions, can be discussed in terms other than just contributions to
national yearly emission inventories. In recent years several research
groups have been looking at the contribution of diesel PM in selected
urban and rural areas. In several cases these studies indicate that the
contribution from diesels in certain urban areas to PM emissions is
much larger than is indicated by national PM inventories. Several
studies have been performed in the past several years which have
attempted to apportion particulate matter collected at specific sites
to individual source categories, i.e., source apportionment studies.
These studies collect particulate matter samples in the ambient air
which are subsequently analyzed using various chemical techniques in
order to estimate what sources contributed to the sample.
There have been a number of source apportionment studies for mobile
source particulate emissions. Among the most recent and thorough are
studies by the state of Colorado (the Northern Front Range Air Quality
Study [NFRAQS]) for the Denver area and the California Institute of
Technology for the Los Angeles area. These studies emphasize
particulate smaller than 2.5 microns. Also, EPA has a cooperative
agreement with the Desert Research Institute (DRI); under this
agreement, DRI is completing a detailed report on mobile source
particulates; a major portion of this report summarizes source
apportionment studies for particulates that include those from mobile
sources.23
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\23\ Draft report for EPA from the Desert Research Institute,
June 30, 1998, Available in EPA Air Docket A-98-32, Item #
--01.
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Source apportionment work involves collecting and analyzing a
number of ambient particulate samples from a number of specific sources
such as gasoline and diesel vehicles. Some samples of high molecular
weight hydrocarbons are frequently also collected and analyzed, these
hydrocarbons can be transformed to particulates in the ambient air;
such compounds include polycyclic organic matter. These samples are
analyzed in detail to determine what specific compounds are present
including those in trace amounts that are more common from one source
type than from others, these traces are called source signatures. From
these analyses, a number of source signatures are developed including
those for gasoline and diesel vehicles. Source apportionment work also
involves collecting and analyzing a larger number of ambient
particulate and, frequently, high molecular weight hydrocarbon. The
compounds found in these samples can be compared to the source
signatures to determine what and how much individual sources contribute
to the ambient particulate.
[[Page 58479]]
Source apportionment work is subject to complications and uncertainty.
Thus, no single study should be considered definitive. Additional
information on source apportionment techniques, and the uncertainties
associated with the techniques, can be found in Chapter 2 of the RIA
for this proposal.
The NFRAQS study analyzed ambient particulate samples in the
Colorado area including Denver using data it collected on the chemical
speciation from specific source types to determine how much various
mobile and stationary source types contribute to PM2.5.
Authorized by Colorado state legislation, the total study was funded by
37 government, industry, and trade association groups. The many outputs
and conclusions from the NFRAQS will not be discussed here, only source
apportionment results for diesel engines are summarized. Complete
copies of the NFRAQS are available from the following World Wide Web
site, http://charon.cira.colostate.edu/. The NFRAQS included several
time periods and several locations in and around Denver. Two locations,
Brighton and Welby, during the winter of 1997 included the most
detailed sampling and analysis, which allowed the researchers to
estimate very detailed source specific contributions, including the
contributions to PM2.5 from diesel exhaust (all diesel,
nonroad and on-highway sources were not differentiated). Based on this
work, it was estimated that diesel exhaust sources contributed 10
percent of the total mass of PM2.5 in the areas of Brighton
and Welby in the winter of 1997.
Similar work has been done for the Los Angeles area by a group of
researchers at the California Institute of Technology. This work
concluded that direct emissions from diesel exhaust represented
approximately 30 percent of fine PM mass on an annual basis in downtown
Los Angeles in 1982.24 In follow-on work looking at the city
of Claremont, California in 1987, direct diesel exhaust was found to
represent approximately 13 percent of PM2.5 mass, and 9
percent of PM10 mass.25
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\24\ ``Source Apportionment of Airborne Particulate Matter Using
Organic Compounds as Tracers'', J.J. Schauer, W.F. Rogge, L.M.
Hildemann, M.A. Mazurek, and G.R. Cass, Atmospheric Environment,
Vol. 30, No. 22, 1996.
\25\ ``Source Contributions to the Size and Composition
Distribution of Urban Particulate Air Pollution'', M.J. Kleeman and
G.R. Cass, Atmospheric Environment, Vol. 32, No. 16, 1998.
---------------------------------------------------------------------------
The California Institute of Technology has also collected ambient
particulate in the Boston, MA and Rochester, NY areas. These samples,
especially those for Boston, show that carbonaceous particulate is the
largest single constituent in PM2.5 for these areas. Mobile
source particulate, including diesels, is an important contributor to
carbonaceous particulate. The Boston and Rochester samples have not yet
been used for source apportionment work.
Other ambient samples collected in the eastern U.S. such as
Washington, DC show carbonaceous particulate to be an important
constituent of PM2.5, although sulfates is a somewhat larger
constituent and nitrates a much smaller constituent. Particulate
samples collected in the western U.S. such as in Spokane, WA, Phoenix,
AZ and the San Joaquin Valley of California show that carbonaceous
particulate is the major constituent with sulfates/nitrates being
lesser constituents although nitrates are more important in southern
California than elsewhere in the United States. This work is summarized
in the EPA report ``National Air Pollutant Emission Trends, 1900-
1996.'' 26
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\26\ ``National Air Pollutant Emission Trends, 1900-1996'', EPA
Report 454/R-97-011, December 1997.
---------------------------------------------------------------------------
The reports on source apportionment summarized in this section
indicate that the contribution of diesel engines to PM inventories in
several local areas around the U.S. are much higher than what would be
assumed from looking only at the estimates presented in national PM
emission inventories. One possible explanation for this is the
concentrated use of diesel engines in certain local or regional areas
which is not well represented by the national, yearly average presented
in national PM emission inventories.
C. Air Toxics From HD Engines and Vehicles
In addition to contributing to the health and welfare problems
associated with exceedances of the National Ambient Air Quality
Standards for ozone and PM10, emissions from HD diesel and
Otto-cycle vehicles include a number of air pollutants that increase
the risk of cancer or have other negative health effects. These air
pollutants include benzene, formaldehyde, acetaldehyde, 1,3-butadiene,
and diesel particulate matter. For several of these pollutants, motor
vehicle emissions are believed to account for a significant proportion
of total nation-wide emissions. All of these compounds are products of
combustion; benzene is also found in nonexhaust emissions from
gasoline-fueled vehicles. These reductions in hydrocarbon emissions
from HD vehicles resulting from today's proposal will further reduce
the potential cancer risk and other health risks from these air toxics
(other than diesel PM) because many of these pollutants are themselves
VOCs. Diesel engine particulate matter is also a potential concern
because of its possible carcinogenic and mutagenic effects on people.
Diesel PM is made of hundreds of chemical species, including many
organic and metallic compounds. Researchers have been investigating the
potential health hazards associated with exposure to diesel PM for many
years.27 EPA's Office of Research and Development is
currently updating the EPA's diesel emission health assessment
document. However, the document has only been released as a preliminary
draft, and is currently undergoing review by the Clean Air Scientific
Advisory Committee. A final version is not expected to be available
until late 1999.28
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\27\ ``Diesel Exhaust: A Critical Analysis of Emissions,
Exposure, and Health Effects'', Health Effects Institute, April,
1995.
\28\ ``Preliminary Draft--Health Assessment Document for Diesel
Emissions'', U.S. EPA, February 1998, EPA 600/8-90/057C.
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The California Air Resources Board and the California Office of
Environmental Health Hazard Assessment (COEHHA) have undertaken an
assessment of the cancer and non-cancer effects from exposure to diesel
exhaust, including the particulate matter component of diesel exhaust,
to determine whether diesel exhaust should be classified as a Toxic Air
Contaminant (TAC) under California law. The evaluation of diesel
exhaust by CARB and COEHHA began in 1989, in June of 1998 a Staff
Report was published which recommended that diesel exhaust be
classified as a TAC.29 In a CARB Board hearing held in
August, the Board decided to identify diesel exhaust particulate matter
as a TAC.30
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\29\ California Air Resources Board--Staff Report--``Proposed
Identification of Diesel Exhaust as a Toxic Air Contaminant'', June
1998.
\30\ California Air Resources Board, Resolution 98-35, August
27, 1998.
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EPA will be addressing the issues raised by air toxics from motor
vehicles and their fuels in a separate rulemaking that EPA is
initiating in the near future under section 202(l)(2) of the Act. That
rulemaking will address the emissions of hazardous air pollutants from
motor vehicles and fuels, and the appropriate level of control of
hazardous air pollutants from these sources.
III. What Is the Important Background Information for This
Proposal?
Under EPA's classification system, heavy-duty vehicles are those
with a
[[Page 58480]]
GVWR of 8,500 pounds or more.\31\ The State of California classifies
the lighter end of this class--up to 14,000 pounds GVWR--as ``medium-
duty vehicles.'' Heavy-duty engines are engines used in heavy-duty
vehicles. Heavy-duty engines and vehicles are used in a wide range of
applications, from large full size pick-up trucks to the largest
commercial trucks. Because one type of heavy-duty engine may be used in
many different applications, EPA emission standards for the heavy-duty
class of vehicles have historically been based on the emissions
performance of the engine (and any associated aftertreatment devices)
as tested separately from the vehicle chassis.
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\31\ The Clean Air Act defines heavy-duty vehicles as those with
a GVWR of 6,000 pounds. However, EPA has classified vehicles between
6,000 and 8,500 pounds GVWR as light-duty vehicles, while treating
them as heavy-duty for statutory purposes. Vehicles weighing between
6,000 and 8,500 pounds GVWR are not addressed generally in this
proposed rulemaking.
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Highway HDEs are categorized into diesel-cycle (compression-
ignited) and Otto-cycle (spark-ignited) engines. Most diesel-cycle
engines are fueled by diesel fuel, but heavy-duty diesel-cycle engines
can also be fueled by methanol or natural gas. The heavy-duty diesel
engine class is further subdivided by EPA into three subclassifications
or ``primary intended service classes''; light, medium, and heavy HDDEs
(see 40 CFR 86.090-2). HDDEs are categorized into one of the three
subclasses depending on the GVWR of the vehicles for which they are
intended, the usage of the vehicles, the engine horsepower rating, and
other factors. The subclassifications allow EPA to more effectively set
requirements that are appropriate for the wide range of sizes and uses
of HDDEs.
Most highway heavy-duty Otto-cycle vehicles and engines are
gasoline-fueled, but may also be fueled with alternative fuels
including methanol and gaseous fuels such as natural gas. Heavy-duty
Otto-cycle vehicles and engines include large full size pick-up trucks,
full size cargo and passenger vans, and the largest sport utility
vehicles. Approximately 75 percent of heavy-duty Otto-cycle vehicles
are in the 8,500-10,000 pound GVWR range, and the vast majority of
these are sold as ``complete'' vehicles. The majority of heavy-duty
Otto-cycle vehicles above 10,000 pounds GVWR are sold as ``incomplete''
vehicles, meaning that they are manufactured without their primary
cargo carrying container or device attached. These incomplete vehicles
(basically the engine plus a chassis) are then manufactured into a
variety of vehicles, including recreational vehicles, panel trucks, tow
trucks, and dump trucks.
EPA's NOX standard for 1998 and later model year diesel
and Otto-cycle heavy-duty engines is 4.0 grams per brake horsepower-
hour (g/bhp-hr). The hydrocarbon standards for 1998 and later model
year Otto-cycle engines are 1.1 g/bhp-hr for engines used in lighter
vehicles (8500 to 14,000 pounds GVWR) and 1.9 g/bhp-hr for engines used
in heavier vehicles (greater than 14,000 pounds GVWR), and the 1998 and
later model year hydrocarbon standard for HDDEs is 1.3 g/bhp-hr. EPA
currently requires testing of the engine (with emissions control
systems in place) rather than the entire vehicle. Thus, the standards
are in units of g/bhp-hr (i.e., grams of emissions per unit of work the
engine performs over the test cycle), rather than the grams-per-mile
unit currently used for testing passenger cars and light-duty trucks.
This proposed rulemaking is the continuation of a rulemaking
process for heavy-duty engines which began in 1995 with an Advanced
Notice of Proposed Rulemaking (ANPRM) (60 FR 45580, August 31, 1995).
As discussed below, a 1996 Notice of Proposed Rulemaking proposed the
same NMHC+NOX standards for both Otto-cycle and diesel
engines (61 FR 33421, June 27, 1996). However, EPA did not finalize the
proposed NMHC+NOX standard for Otto-cycle engines in the
final rule published in October 1997 (62 FR 54694, October 21, 1997).
EPA did finalize a new NMHC+NOX emission standard for HDDEs,
starting with the 2004 model year, but committed to review the
appropriateness of this standard in 1999. This NPRM thus addresses two
broad issues that remain from earlier rulemaking efforts--a review of
the NMHC+NOX standard for diesel engines and a supplemental
proposal addressing new NMHC+NOX standards for heavy-duty
Otto-cycle engines and vehicles. The previous rulemaking documents, and
the documents referenced therein (see EPA Air Docket No. A-95-27),
contain extensive background on the engines and vehicles, the affected
industry, and the need for lower emissions standards.
A. Statement of Principles and Rulemaking History
In July of 1995, EPA, the California Air Resources Board, and
heavy-duty engine manufacturers representing over 90 percent of annual
nationwide engine sales signed a Statement of Principles (SOP) that
established a framework for a proposed rulemaking to address concerns
regarding the growing contribution of heavy-duty engines to air
pollution problems. The SOP contained levels for a new proposed
standard for NMHC+NOX that would become effective in model
year 2004. The SOP also contained several key provisions in addition to
the standards. The SOP discusses the need to review in 1999 the
technological feasibility of the NMHC+NOX standard and its
appropriateness under the Clean Air Act. Also, the SOP outlines a plan
for developing technology with the goal of reducing NOX
emissions to 1.0 g/bhp-hr and particulate matter to 0.05 g/bhp-hr while
maintaining performance, reliability, and efficiency of the engines.
EPA sought early comment on the general regulatory framework laid out
in the SOP in an ANPRM on August 31, 1995 (60 FR 45580), then
subsequently issued an NPRM on June 27, 1996 (61 FR 33421).
On October 21, 1997, EPA issued a final rule (62 FR 54694). The
centerpiece of the final rule was the new NOX + NMHC
standard of 2.4 g/bhp-hr (or 2.5 g/bhp-hr with a 0.5 g/bhp-hr NMHC cap)
for 2004 and later model year heavy-duty diesel-cycle engines. The rule
also adopted other related compliance provisions for diesel-cycle
heavy-duty engines beginning with the 2004 model year, as well as
revisions to the useful life for the heavy heavy-duty diesel engine
service class. As explained in the following section, no new standards
were finalized for on-highway heavy-duty Otto-cycle engines.
The final rule also contained modified ABT provisions for heavy-
duty diesel engines, allowing EPA to finalize a more stringent engine
standard than might otherwise be appropriate under the CAA, since ABT
reduces the cost and improves the technological feasibility of
achieving the NMHC+NOX standard. The changes to the ABT
program provide the manufacturers with additional product planning
flexibility and the opportunity for a more cost-effective introduction
of product lines meeting the new standard. We also believe that the ABT
program can create an incentive for the early introduction of new
emission control technology. EPA did not finalize new ABT provisions
for Otto-cycle engines because EPA did not take action at that time on
new standards for those engines. In summary, engine manufacturers will
be able to generate credits under the new program beginning with the
1998 model year for use only in 2004 and later model years. The credits
in the modified program will have unlimited life, as opposed to the
three year credit life contained in the current HD program. Also,
engines
[[Page 58481]]
with certification levels at or below a certain cut point are able to
generate undiscounted credits. Credits generated by engine families
certified above the specified cut point are discounted by 10 percent
for purposes of banking and trading. The pre-existing ABT program was
retained for engine families using credits before 2004, and for Otto-
cycle engines which cannot earn credits in the modified program, as
noted above. In 2004, the certification level cut-point is adjusted to
reflect the implementation of the new standard.
EPA also finalized several provisions to help ensure in-use
durability. First, EPA increased the useful life period for heavy
heavy-duty diesel engines to 435,000 miles. This new useful life
represents a 50 percent increase and is more representative of the
durability of current and future heavy heavy-duty diesel engines. In
addition, longer allowable maintenance intervals were finalized for
some critical emission-control components, including exhaust gas
recirculation (EGR) systems, catalysts, and other add-on emissions
control components. Generally, the maintenance intervals for the
components are set at 100,000 miles for light heavy-duty diesel engines
and 150,000 miles for medium and heavy heavy-duty diesel engines.
Warranty regulations were also revised to better reflect current
industry practices.
Other provisions of the October, 1997 final rule address the period
after the manufacturer's responsibility for emission control ends,
including engine rebuilding. One of those provisions requires engine
manufacturers to establish a section in the owner's manual for add-on
components that includes recommendations for maintenance and diagnosing
malfunction. In addition, all on-board monitoring used to satisfy the
engine's allowable maintenance must not be designed to turn off after
the end of the useful life. Finally, EPA established provisions to
address engine rebuilding which specify what actions are needed to
ensure proper operation of emissions control components and ensure that
rebuilding does not result in loss of emissions control. Removal or
disabling of emissions related components, resulting in a higher
emitting vehicle, are considered tampering.
B. 1999 Review of Heavy-Duty Diesel Engine NMHC+NOX
Standards
In addition to the elements of the final rule described above, EPA
finalized a regulatory provision providing for a 1999 review of the new
NMHC+NOX emission standard for HDDEs. EPA committed to
``reassess the appropriateness of the standards under the Clean Air
Act, including the need for and technical and economic feasibility of
the standards based on information available in 1999'' (See 62 FR
54699, October 21, 1997). This provision was put in place because the
technologies required to meet the 2004 NMHC+NOX standard for
HDDEs were, at the time the standard was finalized, not yet fully
developed and proven. This commitment was spelled out in regulatory
language in the final rule in 40 CFR 86.004-11, paragraph (a)(1)(i)(E),
which reads:
No later than December 31, 1999, the Administrator shall review
the emissions standards set forth in paragraph (a)(1)(i) of this
section and determine whether these standards continue to be
appropriate under the Act.
In the preamble to the 1997 final rule EPA outlined the three
potential outcomes of the 1999 review: further tightening of the
NMHC+NOX standard, no change to the standard, or a
relaxation of the standard. The preamble noted that if EPA determined
through the 1999 review process that a tighter standard was feasible
and appropriate under the Clean Air Act, such tighter standard would be
proposed. Conversely, if EPA's 1999 review process concluded that the
2004 NMHC+NOX standard was not technologically feasible, the
1997 preamble outlined alternative less stringent sets of standards
that EPA would propose. These alternative less stringent standards
would depend on EPA's conclusions regarding the necessity for diesel
fuel changes and, if changes were found to be needed, whether or not
EPA took action to require such changes. Specifically, the preamble
stated that if EPA finds through the 1999 review process that the
existing 2004 NMHC+NOX standard is not feasible, a standard
no higher than 2.9 g/bhp-hr NMHC+NOX (or 3.0 g/bhp-hr
NMHC+NOX with a limit of 0.6 g/bhp-hr NMHC) would be
proposed. If EPA were to find that changes to diesel fuel would be
necessary to meet the 2004 NMHC+NOX standards, and if EPA
did not engage in a rulemaking to make such changes, then standards no
higher than 3.4 g/bhp-hr NMHC+NOX (or 3.5 g/bhp-hr
NMHC+NOX with a limit of 0.6 g/bhp-hr NMHC) would be
proposed.
While the specific regulatory provision is limited to the
NMHC+NOX standard for review in 1999, in the preamble to the
final rule EPA committed to investigating or seeking comment on several
other issues in the context of the 1999 review. These additional issues
include:
An evaluation of whether the appropriateness and technical
feasibility of the 2004 standards depend upon changes to diesel fuel.
A reassessment of the appropriateness of the 2004
NMHC+NOX standard in the context of the current PM standard.
Non-conformance penalty provisions for the 2004 HDDE
standards.
C. Proposal for Heavy-Duty Gasoline Engine Standards
1. Summary of Comments on 1996 NPRM
As was noted above, EPA proposed the same NMHC+NOX
standard for diesel and Otto-cycle heavy-duty engines in the 1996 NPRM.
In the comment period following the NPRM, several commenters urged the
Agency to reconsider its proposal for Otto-cycle engines. The
commenters argued that the proposal ignored the true low emissions
capability of gasoline-powered vehicles equipped with advanced three
way catalysts. Environmental groups provided comments highlighting
manufacturers' certification data for the 1996 model year, which
included some engine families with emission levels considerably below
the standards proposed for the 2004 model year. One commenter
recommended that the proposed standard be phased in earlier than 2004
for Otto-cycle engines since the emissions control technology capable
of meeting the NMHC+NOX standard was more advanced for Otto-
cycle engines than for diesel engines.
Manufacturers commented that the proposed standard was appropriate
for Otto-cycle engines and that EPA should not use certification data
as a basis for determining the feasibility of a lower standard.
Manufacturers noted that due to the potential for in-use deterioration
of catalysts and oxygen sensors, they must design to emissions targets
and certification levels well below the standards. Catalysts experience
wide variations in exhaust temperature due to the wide and varied usage
of vehicles in the field. Some vehicles may experience more severe in-
use operation than is represented by the durability testing conducted
for engine certification. Manufacturers argued that this variation in
in-use operation has an impact on emission system durability not
represented by engine certification data and deterioration factors.
They argued that it is necessary to certify engines to levels well
below the standards to ensure in-use compliance of all engines. One
manufacturer presented light-duty
[[Page 58482]]
vehicle and light-duty truck data to demonstrate that certification
levels were about half the standard while some vehicles' in-use
emissions levels were higher although not above the standard.\32\
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\32\ Comments from Kelly Brown, Ford Motor Company, to Margo
Oge, Director OMS, U.S. EPA, September 9, 1996, Docket A-95-27, IV-
D-26.
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2. Analysis Leading to Decision To Not Finalize Otto-Cycle Standards
EPA, in deciding whether to finalize the NMHC+NOX
standard as originally proposed, had to determine if the proposed
standards met the requirements of section 202(a)(3)(A) of the Clean Air
Act.\33\ For Otto-cycle engines, EPA examined 1997 model year
certification data and found some engines certified to very low
emissions levels. The certification data for 1997 showed a large number
of engine families emitting at or below the 2004 levels as they were
proposed, with some engines certified at emission levels only ten to
twenty percent of the proposed 2004 emission standards. Examples of
these engines are listed in Table 2.\34\
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\33\ Section 202(a)(3)(A) of the Clean Air Act specifies that
regulations ``shall contain standards which reflect the greatest
degree of emission reduction achievable through the application of
technology which the Administrator determines will be available for
the model year to which such standards apply, giving appropriate
consideration to cost, energy, and safety factors associated with
the application of such technology.''
\34\ Note that the text here is a brief assessment of the
information EPA had available at the time a decision was made to
refrain from finalizing heavy-duty Otto-cycle standards. However,
today's proposal, and the accompanying analysis of feasibility in
the RIA, uses more recent data.
Table 2.--1997 MY Heavy-Duty Otto-Cycle Engine Certification Data
----------------------------------------------------------------------------------------------------------------
NOX HC certification
Engine size (liter) certification level (g/bhp- NOX + HC (g/bhp-
level (g/bhp-hr) hr) hr)
----------------------------------------------------------------------------------------------------------------
4.3....................................................... 1.2 0.3 1.5
5.4....................................................... 0.2 0.1 0.4
5.7....................................................... 1.4 0.1 1.5
6.8....................................................... 0.1 0.1 0.2
7.4....................................................... 1.2 0.4 1.6
8.0....................................................... 2.2 0.1 2.3
Emission Standards........................................ 5.0 *1.3 N/A
----------------------------------------------------------------------------------------------------------------
*(1.9 above 14,000 pounds GVWR)
EPA also examined certification data for California vehicles.
California's MDV program requires all complete heavy-duty vehicles
(i.e., all vehicles that exit the manufacturer's assembly line with
their cargo carrying device or container attached) up to 14,000 pounds
GVWR to be certified on the chassis-based (vehicle) federal test
procedure (EPA currently requires engine-based testing of vehicles in
this class). Table 3 lists examples of model year 1997 California
vehicle certification results for vehicles above 8,500 pounds GVWR.\35\
These vehicles were required to meet the California Tier 1 standards
which are listed on the table. Starting with the 1998 MY, California is
requiring manufacturers to begin phase-in of vehicles meeting more
stringent Low Emission Vehicle (LEV) standards which are also listed in
Table 3 for these vehicles.
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\35\ All of the vehicles and standards listed are categorized
MDV3 in the medium duty vehicle program which includes vehicles with
test weights between 5,751-8,500. Test weight is the average of the
curb weight and gross vehicle weight.
Table 3.--1997 MY California Medium-Duty Vehicle Certification Data
[120,000 mile]
----------------------------------------------------------------------------------------------------------------
NOX level (g/ HC level (g/ NOX+HC (g/
Engine size (liter) mile) mile) mile)
----------------------------------------------------------------------------------------------------------------
5.4............................................................. 0.20 0.220 0.42
5.7............................................................. 0.88 0.160 1.04
6.8............................................................. 0.42 0.300 0.72
7.4............................................................. 0.48 0.210 0.69
7.5............................................................. 0.24 0.190 0.43
8.0............................................................. 0.51 0.234 0.74
Tier 1 standards................................................ 1.53 0.560 N/A
LEV standards................................................... 0.90 0.280 N/A
----------------------------------------------------------------------------------------------------------------
EPA understands that manufacturers have established certification
levels which represent typical vehicle usage and that manufacturers
have given themselves a significant margin between the certification
levels and the standards to account for variability including more
severe usage and deterioration. However, EPA found that some 1997 model
year engines were certified to very low levels even taking the need for
a compliance margin into consideration. At the time, however, EPA did
not believe it was appropriate, given the lack of a full opportunity
for notice and comment, and the need for more thorough data and
analyses, to proceed directly to finalizing standards tighter than
those originally proposed for heavy-duty Otto-cycle engines. For these
reasons, EPA did not finalize the proposed standards for Otto-cycle
engines and asserted that more stringent standards might be reasonably
achievable in the 2004 model year time frame. With the lead time
available for the 2004 time frame and in the context of EPA's emission
control program at the time, EPA concluded in 1997 that final action
establishing an appropriate standard for Otto-cycle heavy-duty engines
should be the subject of a future action that more thoroughly assessed
[[Page 58483]]
whether a more stringent standard might be achievable and appropriate
for some or all categories of Otto-cycle heavy-duty engines.
D. Consent Decrees With Heavy-Duty Diesel Engine Manufacturers
The Department of Justice and EPA recently filed proposed consent
decrees with seven of the largest heavy-duty diesel engine
manufacturers in the U.S. in order to resolve the problems uncovered
from current and past heavy-duty diesel engines which the government
does not believe meet existing standards and defeat device rules. (See
63 FR 59330-59334; November 3, 1998). In these consent decrees with the
Federal Government these manufacturers have agreed, among other things,
to meet a 2.5g/bhp-hr limit on NMHC+NOX no later than
October 1, 2002. The majority of these engine manufacturers have also
agreed to produce engines by October 1, 2002 which meet a 1.25 not-to-
exceed limit, a 1.0 Euro III limit (on which the Agency's proposed
supplemental steady-state cycle is based), and to test engines over and
eventually comply with a load response test and limit. \36\ The fact
that these engine manufacturers have agreed to meet the 2004 standards
in 2002 gives the Agency additional confidence that the
NMHC+NOX standard being reaffirmed in today's proposal is
appropriate for the 2004 model year. Other elements of these consent
decrees that are carried over to today's proposed rule include the
addition of a new steady state certification test and a new ``not-to-
exceed'' (NTE) approach to in-use testing. In addition, under the
consent decrees the manufacturers are required to invest considerable
resources to evaluate instrumentation and methodologies for on-road
testing, providing an additional basis for EPA's expectations regarding
the advancement of technology in this area.
---------------------------------------------------------------------------
\36\ The Consent Decrees establish target limits for a load
response test of 1.3 times the federal test procedure (FTP) standard
for NMHC+NOX and 1.7 times the FTP standard for PM. These
limits would take effect for affected manufacturers after October 1,
2002. However, the Consent Decrees establish a process to determine
whether these limits should be modified to ensure that they are the
lowest achievable given the technology available at the time. Under
this process, manufacturers would submit load response test data
with their certification applications starting with the 1999 model
year, and by October 1, 2000, the parties to the Consent Decrees
would review these data to determine appropriate emission limits.
---------------------------------------------------------------------------
The Agency believes these consent decrees will partially address
the emission problems from these previously produced engines. However,
we do not believe that relying on the current compliance program and
the use of enforcement actions in the future is the most appropriate
method to assure in-use compliance of heavy-duty engines under all
operating conditions. We estimate that the more than 1,000,000 engines
at issue in these consent decrees produced since 1988 will have
resulted in excess NOX emissions of more than 15 million
tons over the lifetime of the engines, with an estimated 1.3 million
excess tons of NOX being emitted in 1998 alone. This level
of NOX emissions is enormous. To put this in perspective,
the Agency's National Air Pollutant Emission Trends report for 1900-
1996 estimates the total U.S. emission inventory for annual
NOX emissions was 23.3 million tons. These estimates do not
include the previously unknown excess NOX emissions from on-
highway heavy-duty diesels. Assuming the total 1998 national
NOX emissions are similar to 1996, the 1.3 million tons
excess NOX emissions from heavy-duty diesels in 1998
represent approximately five percent of the national total. We believe
the new compliance requirements proposed in this NPRM must be put in
place in order to assure that the public's health and welfare are
protected from these types of excess emissions in the future.
IV. What Are the Details of This Proposal?
A. Reaffirmation of 2004 NMHC + NOX Standard for Heavy-Duty
Diesel Engines
In today's proposal, the Agency is reaffirming the technological
feasibility, cost-effectiveness, and appropriateness under the Clean
Air Act of the 2004 NMHC+NOX standard for HDDEs, including
the appropriateness of the current 0.1g/bhp-hr PM standard. In 1997,
the Agency finalized on-highway heavy-duty diesel standards for model
year 2004 of:
2.4 g/bhp-hr NMHC + NOX
or
2.5 g/bhp NMHC + NOX with a limit of 0.5 g/bhp-hr on NMHC
For today's proposal, the Agency has conducted a thorough analysis
of information and data which has become available since the
finalization of these standards in October of 1997. As discussed
elsewhere in this preamble and in the RIA for this proposal,
manufacturers have made significant progress toward meeting the 2004
standards, and in fact, the Agency believes a large number of
manufacturers will be meeting the 2004 model year standards by the end
of 2002. Manufacturers have made significant progress in several key
technologies for HD diesels which will allow them to meet the 2004
NMHC+NOX standards. These areas included advanced fuel
injection systems, EGR, advanced turbocharger systems, and advanced
electronic controls. In the relatively short time frame since the
finalization of the 1997 rule, manufacturers have either announced or
begun to introduce second generation electronically controlled fuel
injection systems, such as the Cummins Accumulator Pump system (CAPS),
and the Navistar/Caterpillar second generation hydraulicly actuated
electronic unit injections (HEUI) and mechanically actuated electronic
unit injection (MEUI) systems.\37\ \38\ \39\ \40\ \41\ These newer
systems provide manufacturers with enormous capabilities to tailor-fit
engine injection pressures, injection rate shaping, and pilot injection
(or multiple pilot injections) to lower NOX emissions while
still complying with the current PM standard, and maintaining or
improving upon the fuel efficiency, performance, and durability
expected by HDDE users. These advanced fuel systems will be coupled
with new, sophisticated EGR systems. As discussed in the RIA,
considerable research has been done in the last few years on the
application of EGR to heavy-duty diesels in order to meet the 2004
standards. Based on this relatively recent information, it now appears
manufacturers will use a combination of hot and cooled EGR, sometimes
at relatively high EGR flow rates, on the order of 40-50 percent under
certain operating conditions, to achieve the 2004 NMHC+NOX
standards. The Agency believes EGR is perhaps the single most
significant advance in emission control technology for HD diesels which
will enable the approximately 50 percent reduction in NOX
emissions required by the 2004 standards. As discussed in the draft
RIA, cooled EGR is very effective at reducing NOX emissions.
Laboratory studies have shown that EGR can reduce NOX
emissions by up to 90 percent at
[[Page 58484]]
light load and up to 60 percent at full load near rated
speed.42 Other studies have shown similar reductions at
other speeds and loads.43 In addition to fuel system changes
and EGR, turbocharger manufacturers and engine manufacturers are in the
process of developing new variable nozzle turbochargers (VNT, sometimes
referred to as variable geometry turbochargers), as well as more
advanced, electronically controlled wastegated turbochargers, for both
performance and emission reasons. The new VNT systems will allow
manufacturers more flexibility in how they design their EGR systems,
and provide improved performance for engine users. Finally, engine
manufacturers continue to develop and introduce highly sophisticated
electronic control management systems based on the latest
microprocessor technology available.\44\ These next generation control
systems integrate the complete engine/powertrain system, including the
injection system, EGR, and turbocharger, which allows the manufacturer
to maximize the engine performance as well as emission control system.
The RIA for this proposal provides additional detail on these
technologies, as well as the Agency's cost analysis for the combination
of technologies which EPA expects will be used to meet the 2004
NMHC+NOX standards. Based on the most recent information
available, the Agency is confident that engine manufacturers are making
sufficient progress in the development of technologies which will allow
them to meet the 2004 NMHC+NOX standards. As discussed
below, the Agency does not believe changes in diesel fuel quality are
needed for engines to meet these standards.
---------------------------------------------------------------------------
\37\ SAE paper 973182, ``Advanced Technology Fuel System for
Heavy-duty Diesel Engines''.
\38\ Diesel Progress, August 1998, ``CAT Gears Up Next
Generation Fuel Systems'', available in EPA Air Docket A-98-32,
Docket Item #II-D-03.
\39\ Diesel Progress, August 1998, ``Next Generation MEUI-B to
Debut in 2001'', available in EPA Air Docket A-98-32, Docket Item
#II-D-03.
\40\ Diesel Progress, October 1998, ``No Mistaking New Cummins
ISL Engine'', available in EPA Air Docket A-98-32, Docket Item #II-
D-04.
\41\ ``Cummins New Midrange Fuel System'', presented by John
Youngblood, Cummins Engine Company, at the SAE Diesel Technology
TOPTEC, April 22, 1998, available in EPA Air Docket A-98-32, Docket
Item #II-D-01.
\42\ Dickey D.W., T.W. Ryan III, A.C. Matheaus: ``NOX
Control in Heavy-Duty Engines-What is the Limit?'', SAE paper
980174, 1998. Dickey; and, Zelenka P., H. Aufinger, W. Reczek, W.
Cartellieri: ``Cooled EGR-A Key Technology for Future Efficient HD
Diesels,'' SAE paper 980190, 1998.
\43\ Kohketsu S., K. Mori, K. Sakai, T. Hakozaki: EGR
Technologies for a Turbocharged and Intercooled Heavy-Duty Diesel
Engine,'' SAE paper 970340, 1997; Baert R., D.E. Beckman, A.W.M.J.
Veen: ``EGR Technology for Lowest Emissions,'' SAE paper 964112,
1996; and, Heavy-duty Engine Working Group, Mobile Source Technical
Advisory Subcommittee of the Clean Air Act Advisory Committee,
``Phase 2 of the EPA HDEWG Program--Summary Document'', available in
EPA Air Docket A-98-32.
\44\ See for example SAE paper 981035, ``The Cummins Signature
600 Heavy-Duty Diesel Engine'' T.R. Stover, D.H. Reichenbach, and
E.K. Lifferth, Cummins Engine Co., Inc., Feb., 1998.
---------------------------------------------------------------------------
In addition, as noted in section III.D, the fact that several
heavy-duty diesel engine manufacturers have agreed to meet the 2004
standards in 2002 gives the Agency additional confidence that the
NMHC+NOX standard being reaffirmed in today's proposal is
appropriate for the 2004 model year.
As discussed in section IX, and in the draft RIA, EPA does not
believe more stringent standards for the 2004 model year are
technologically feasible, giving appropriate consideration to cost,
energy, and safety factors. Technologies which could reduce emissions
significantly below the 2004 standards, such as NOX absorber
catalysts, are still in the research and development stage, and do not
appear to be ready for the 2004 model year. The Agency has also
examined technologies to reduce PM from HD diesel engines, including
diesel oxidation catalysts and particulate traps. As discussed in the
draft RIA, we believe the current PM standard of 0.1 g/bhp-hr (0.05 for
urban buses) continues to be the appropriate standard for the 2004 time
frame. However, in section X of today's proposal we discuss the
possible feasibility of more stringent standards in later model years,
although no specific proposals are made today.
B. Are Changes in Diesel Fuel Quality Necessary To Meet the 2004
Standards?
The purpose of this section is to assess the current understanding
of the role diesel fuel quality plays in the ability of diesel engines
to meet the 2004 NMHC+NOX emission standards and to
determine whether these standards can be met using currently available
fuel. It has long been realized that diesel engine technology alone is
not the only mechanism to lower NOX emissions. Diesel fuel
quality also plays an important role in emission formation, as well as
engine performance. In addition, diesel fuel quality can play a role in
the effectiveness of certain emission control technologies, and in some
cases can be considered a technology enabler, i.e., some emission
control devices may not function because of certain diesel fuel
properties, such as sulfur content. In EPA's 1997 final rulemaking for
the 2004 standards, we stated that we believed the 2004 standards were
appropriate and technologically feasible through diesel engine
technology modifications alone, without changes to diesel fuel quality
(see 62 FR 54700, Oct. 21, 1997). However, we also stated that this
issue would be revisited in the 1999 technology review rulemaking.
``EPA will evaluate in light of any new information whether diesel fuel
improvements are needed for the standards to be appropriate for 2004.''
(See 62 FR 54700, Oct. 21, 1997).
Section V.A. of this preamble (``2004 Emission Standards for Heavy-
duty Diesel Engines'') and Chapter 3 of the draft RIA for this proposal
(``Technological Feasibility of HD Diesel and Otto-cycle Standards'')
discuss in detail the technologies we believe will enable HD diesel
engines to meet the 2004 standards, on existing U.S. HD diesel fuel.
These technologies include cooled EGR, advanced fuel injection systems
with rate-shaping ability, advanced turbocharger designs (such as
variable nozzle turbochargers), and electronic engine management. These
technologies have been demonstrated to produce significant emission
reduction, independent of changes in current U.S. diesel fuel quality.
Based on the information discussed in section V.A. of this preamble and
Chapter 3 of the draft RIA, and based on the fact that these emission
control technologies can produce substantial emission reductions using
current diesel fuel, we conclude no change in diesel fuel quality is
necessary to meet the 2004 NMHC+NOX standard. We request
comment on this conclusion, and encourage commenters to supply any data
and information that may support their comments.
Engine manufacturers have recently raised concerns to EPA regarding
the potential negative effects of current diesel fuel sulfur levels on
engine durability for 2004 technology engines for the full useful life
of the engines. As discussed in Chapter 3 of the draft RIA for this
rule, the use of cooled EGR systems to meet the 2004 standards can give
rise to potentially significant concentrations of sulfuric acid
formation in the recirculated exhaust if the EGR system cools the
exhaust below the water vapor dew point. In addition, some HD diesel
engine manufacturers have expressed specific concern regarding the
extended useful life for the heavy-heavy duty diesel service class
which goes into effect in 2004. In the 1997 final rulemaking for on-
highway heavy-duty diesel engines, EPA revised and extended the useful
life for the heavy-heavy service class from 290,000 miles to 435,000
miles (see 62 FR 54700, October 21, 1997). Several manufacturers have
suggested EPA should reconsider this useful life extension due to their
concerns with engine durability, diesel fuel sulfur, and cooled EGR
systems. These manufacturers have suggested EPA implement the extended
useful life contingent upon federal diesel fuel standards meeting some
threshold maximum fuel sulfur content. However, the Agency believes
manufacturers will design cooled EGR systems to limit sulfuric acid
formation and to prevent in-use durability problems. As
[[Page 58485]]
discussed in the RIA (section 3.II.B), EPA expects engine manufacturers
to maintain EGR cooler systems slightly above the water vapor dew
point, particularly at high load. In addition, EPA expects
manufacturers to utilize EGR systems made of sulfuric acid corrosive
resistant materials (such as specially treated stainless steel) to
prevent deterioration of the EGR system. We request additional
information and supporting data on the manufacturers' concerns
regarding durability issues associated with the 2004 standards. We
request specific comment and supporting data on the manufacturers'
concerns, including any in-use or laboratory durability data, and any
data which would support or refute the manufacturers' contentions
regarding the need for a shorter useful life for the heavy-heavy
service class.
In the remainder of this section, we review the new information
which has become available since the 1997 rulemaking through a study
performed by the Heavy-duty Engine Working Group.
In anticipation of the need for new information regarding the
influence of diesel fuel quality on future emission technologies and
achievable levels, in December of 1995 a new Working Group called the
Heavy-duty Engine Working Group (HDEWG) was formed under the Mobile
Source Technical Advisory Subcommittee of the Clean Air Act Advisory
Committee. The HDEWG consists of approximately 30 members, including
representatives from EPA, heavy-duty engine original equipment
manufacturers (OEMs), the oil industry, state air quality agencies,
private consultants and members of academic institutions. The HDEWG
formed a steering committee which consisted of representatives from
EPA, Cummins, Caterpillar, Navistar, Ford, British Petroleum, Equilon,
Mobil Oil, Phillips, the Engine Manufacturers Association, the American
Petroleum Institute, and the National Petroleum Refinery Association.
The HDEWG set as their research objective to contribute to EPA's 1999
technology review of the NMHC+NOX emission standards for
model year 2004 heavy-duty diesel engines by assessing relative merits
of achieving 2.5 g/bhp-hr NMHC+NOX level either through
engine system modifications alone, or a combination of engine system
and fuel modifications.
The HDEWG established a three phase process in order to meet their
objective. In Phase 1, the goal was to determine whether the combined
effects of diesel fuel properties on exhaust emissions of ``black
box'',45 advanced prototype engines being developed by
engine manufacturers were large enough to warrant a Phase 2. However,
the details of each black box engine would not be shared with the
HDEWG. In addition, the HDEWG agreed to use one ``transparent'' engine
at an independent test facility, Southwest Research Institute (SwRI).
During Phase 1, testing was to be performed on the transparent engine
at SwRI, as well as the black box engines at manufacturers' own testing
facilities, to determine if the transparent engine was representative
of the black box engines with respect to diesel fuel effects on
NOX emissions. Phase 2 of the program, which would occur
upon successful completion of Phase 1, would be used to test a range of
relevant fuel properties on the transparent engine at SwRI, in order to
determine the effects of various fuel properties on emissions. Finally,
Phase 3 of the test program would determine whether or not the results
seen during Phase 2 on the transparent engine was in fact
representative of black box engines, i.e., advanced prototype engines
being developed by engine manufacturers to meet the 2004 standards.
Phase 3 would be performed at engine manufacturers' laboratories using
a subset of the fuel matrix from Phase 2.
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\45\ ``Black box'' engines are advanced engines being designed
by engine manufacturers to meet the 2004 standards.
---------------------------------------------------------------------------
At the time of the publication of this proposal, Phase 1 and Phase
2 of the program have been completed. Phase 3 is expected to be
completed by the end of 1999. The RIA for this proposal contains a
detailed discussion of the Phase 1 and Phase 2 portions of the HDEWG
test program. The reader should see Chapter 3 of the draft RIA for this
proposal for a detailed description.
The HDEWG's primary focus was on the effects of diesel fuel
properties on HC and NOX emissions, not on PM emissions, and
therefore fuel sulfur level was not investigated. A significant amount
of data exists on the effects of diesel fuel sulfur on engine
emissions, and in fact this data was summarized recently in a paper
published by members of the HDEWG.46 Existing data on recent
model year HD engines indicates diesel fuel sulfur level does have a
statistically significant effect on PM emissions, but no statistically
significant effect on HC, carbon monoxide (CO), or NOX
emissions for engines with no exhaust aftertreatment. For this reason,
and because of the focus on NMHC and NOX emissions, as well
as the limitations of the prototype SwRI transparent engine, the HDEWG
did not include fuel sulfur level as a variable in Phase 1, 2 or 3 of
their test program, nor were PM emissions measured during Phase 1 or 2.
The Phase 3 test program, done at individual engine manufacturers'
facilities, will include PM measurement.
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\46\ See Lee, R., Pedley, J., and Hobbs, C., ``Fuel Quality
Impact On Heavy-Duty Diesel Emissions:--A Literature Review'',
Society of Automotive Engineers paper number 982649, 1998.
---------------------------------------------------------------------------
The HDEWG concluded two points based on the results of the Phase 1
testing. First, initial testing on a limited set of diesel fuel
formulations (fuel batches with high cetane number and low aromatics)
on advanced prototype engines by the engine manufacturers showed a
change in NOX emissions which warranted additional testing
under Phase 2. Second, the ``transparent'' engine at SwRI performed in
a way that was representative of engine manufacturers' advanced
prototypes, and was therefore an adequate test engine for Phase 2.
The purpose of the Phase 2 component of the test program was to
test a range of relevant fuel properties on the transparent engine at
SwRI in order to determine the effects of various fuel properties on
emissions. All testing during Phase 2 of the test program was done at
SwRI on the transparent engine. Based on the results of the Phase 1
testing, as well as the literature review performed under Phase 1, the
HDEWG selected four fuel properties for investigation under Phase 2:
density, cetane (natural and ``boosted'' 47), monoaromatic
content and polyaromatic content. As mentioned previously, fuel sulfur
level was not investigated. A test matrix was designed to decouple
these fuel properties from each other. The design matrix included two
levels of density, monoaromatic hydrocarbons, polyaromatic
hydrocarbons, and three levels of cetane, with duplicate test points
for both natural and ``boosted'' cetane. The final matrix included
eighteen test fuels, with density varying from 830 to 860 kg/m\3\,
cetane numbers from 42 to 48 to 53, monoaromatic content from 10 to 25
percent, and polyaromatic content from 2.5 to 10 percent. The test
cycle used by SwRI was the AVL 8-mode test. This steady-state test
cycle, with associated weighting factors, has been shown in the past to
correlate very well with NOX emissions measured over the
U.S. heavy-duty federal test procedure (FTP). All emission tests were
performed at least in duplicate. The transparent engine used a SwRI is
a modern, heavy-heavy duty diesel engine with
[[Page 58486]]
electronically controlled unit injectors capable of meeting the U.S.
1998 model year emission standards. This engine was modified by SwRI
with the addition of a prototype, low-pressure loop, cooled EGR system
with manual control of EGR flow rates. For the Phase 2 test program,
SwRI selected EGR rates necessary to approach an AVL 8-mode composite
NOX level of 2.5g/hp-hr.
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\47\ Boosted cetane is achieved by the addition of a fuel
additive, in this case ethylhexyl nitrate.
---------------------------------------------------------------------------
The large quantity of test data generated by the test program was
evaluated using statistical techniques in order to develop exhaust
emission and fuel consumption prediction models based on the four fuel
properties. All properties were evaluated using a significance level of
five percent. The data generated during Phase 2 indicates that for
engines utilizing advanced fuel injection and a cooled EGR system
operating at emissions levels near the 2004 standards the effects of
large changes in individual fuel properties on HC+NOX
emissions are rather small, and for cetane number not statistically
significant. A large decrease in fuel density, from 860 to 830 kg/
m3, or in monoaromatic content, from 25 to 10 percent, is
predicted to result in a 4.3 percent decrease in HC+NOX
emissions. A large decrease in polyaromatics content, from 10 to 2.5
percent, is predicted to result in a 2.3 percent decrease in
HC+NOX emissions.
The Phase 2 data was also analyzed to predict the combined effects
from diesel fuel changes on emissions, not just single property
changes. The Phase 2 model was used to predict the effect of fuel
modifications from current, average U.S. on-highway diesel fuel to a
``cleaner'', reformulated diesel fuel, one with low density (830 kg/
m3), high cetane (52), low monoaromatics (10 percent), and
low polyaromatics (2.5 percent). The Phase 2 model predicts this
significant change in U.S. diesel fuel formulation would result in a
8.4 percent decrease in HC+NOX emissions.
The Phase 3 results are currently not available. However, based on
what has been seen in the Phase 1 and Phase 2 portions of this test
program, we do not believe a change in diesel fuel formulation is
required to make the 2004 model year NMHC+NOX standards
technologically feasible and appropriate under the CAA. The data from
the Phase 1 and 2 portions of the HDEWG does indicate that a change in
diesel fuel formulation could provide for a small reduction in
HC+NOX emissions from HD diesels, on the order of an 8
percent reduction. An assessment of the appropriateness of such a
diesel fuel reformulation, beyond the 2004 standards with existing HD
diesel fuel, is outside the scope of this rulemaking.
C. Otto-Cycle Engine-Based Program
We are proposing an NMHC+NOX standard for Otto-cycle
engines for 2004 and later model years, but are limiting the
applicability of this new standard to engines used in vehicles over
14,000 pounds GVWR and in incomplete vehicles. 48 (We are
also proposing new vehicle standards for the remaining engines, as
discussed in later sections.) We are not proposing to apply the vehicle
standards to these engines at this time. Engines used in incomplete
vehicles are manufactured for use in many different kinds of heavy-duty
vehicles by many different manufacturers. Vehicles in the weight
categories above 14,000 pounds GVWR tend to be quite large and varied
compared to pick-up trucks and full-size vans, and most dynamometer
test facilities are currently not equipped to accommodate vehicles in
this size range. Additionally, this approach is consistent with
California which allows engine-based testing for these vehicles in its
Medium-duty Vehicle program.
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\48\ Incomplete vehicles less than 14,000 lbs GVWR could
optionally certify to the proposed new vehicle standards, as
discussed in a later section.
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1. Engine Exhaust Emissions Standards
We propose a NMHC+NOX standard of 1.0 g/bhp-hr for MY
2004 and later for those Otto-cycle engines in the engine-based
program. The proposed standard represents a reduction in the
NOX and HC standards of over 75 percent. EPA believes that
this standard represents the most stringent standard reasonably
achievable for these engines, in keeping with the requirements of the
CAA. EPA's analysis of the technological feasibility of a 1.0 g/bhp-hr
NMHC+NOX standard is contained in Technological Feasibility
section below. We also believe that the ABT program proposed for
engines provides manufacturers with the needed flexibility to meet the
new standard as their product lines become subject to the new engine
standards. The ABT provisions are also described below. In their
assessment of the feasibility of new engine-based standards, engine
manufacturers recommended a standard of 2.0 g/bhp-hr
NMHC+NOX. The Technological Feasibility section also
contains a discussion of the manufacturer's recommendations. EPA
requests specific comment on a range of possible standards, from the
proposed standard of 1.0 g/bhp-hr to 1.5 g/bhp-hr, and on the standard
of 2.0 g/bhp-hr proposed by engine manufacturers.
2. Averaging, Banking, and Trading for Otto-Cycle Engines
As part of proposing more stringent engine-based standards, EPA is
proposing a modified ABT program for these engines. The program is
similar in design to the program adopted for diesel engines. EPA is
proposing ABT modifications to allow more flexibility within the ABT
framework to help meet the more stringent standards. ABT credits can
help manufacturers with engine configurations that are more difficult
to modify, where more time would help reduce costs. Credits can also
allow manufacturers to continue with product plans that might call for
the retirement of an engine family at some point shortly after 2004. By
banking credits manufacturers can also reduce their uncertainty or risk
associated with the new standards. In the Summary and Analysis of
Comments for the Diesel Final Rule, EPA explained why the modified ABT
program adopted in that rulemaking will not decrease emissions
reductions associated with the new standards. 49 Similarly,
EPA believes that the modified ABT program proposed in this rulemaking
also will not decrease emissions reductions associated with the new
standards.
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\49\ See EPA Air Docket No. A-95-27.
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The ABT program has been used for only one Otto-cycle engine family
to meet the current 4.0 g/bhp-hr NOX standard which went
into effect in the 1998 model year. In other cases, advances in
catalyst technology and engine/fuel system improvements have allowed
manufacturers to meet the standard across their product line. Most
engine families have certification levels of less than half the
standard. However, with the proposed standard for 2004, EPA expects ABT
to become a more important tool for Otto-cycle engine manufacturers.
An ABT program allows the Agency to propose and finalize a more
stringent engine standard than might otherwise be appropriate under the
CAA, since ABT reduces the cost and improves the technological
feasibility of achieving the standard. EPA is proposing changes to the
ABT program with the intent that the changes would enhance the
technological feasibility and cost-effectiveness of the new standard,
and thereby help to ensure the new standard would be attainable earlier
than would otherwise be possible. The changes would provide
manufacturers with additional product planning flexibility and the
opportunity for a more cost effective introduction of product lines
[[Page 58487]]
meeting the new standard. Also, EPA believes that ABT creates an
incentive for early introduction of new technology which allows certain
engine families to act as trail blazers for new technology. This can
help provide valuable information to manufacturers on the technology
prior to manufacturers needing to apply the technology throughout their
product line. This further improves the feasibility of achieving the
standard. This early introduction can also provide valuable information
for use in other regulatory programs that may benefit from similar
technologies (e.g., nonroad programs). EPA views the effect of the ABT
program itself as environmentally neutral because the use of credits by
some engines is offset by the generation of credits by other engines.
However, when coupled with the new standards, the ABT program would be
environmentally beneficial because it would allow the new standards to
be implemented earlier than would otherwise be appropriate under the
Act.
EPA proposes the following provisions for the modified ABT program
for Otto-cycle engines:
Manufacturers could bank NOX credits beginning
in MY 2000 for MYs 2004 and later.
Credits would be earned up to a NOX level of
2.0 g/bhp-hr.
Credits would be discounted by 10 percent for engine
families with FELs above the 1.0 g/bhp-hr NMHC+NOX level
(i.e., the proposed standard) and undiscounted for engine families with
FELs at or below the 1.0 g cut point.
For model year 2004 and later, engine families with FELs
above 0.5
g/bhp-hr NMHC+NOX (i.e., one-half of the proposed standard)
would be discounted by 10 percent. Engine families with FELs at or
below 0.5
g/bhp-hr would earn undiscounted credits.
As with the diesel program, NOX credits banked
prior to 2004 would be used to meet the combined NMHC+NOX
standard in 2004 and later.
Credits banked under the modified program would have
unlimited credit life.
Engine families using credits after MY 2004 may not exceed
the previous NOX standard of 4.0 g/bhp-hr.
Engine families generating credits prior to 2004 must meet
the revised requirements for deterioration factors noted above.
Prior to 2004, manufacturers could continue to use the current ABT
program. EPA proposes that the current program would end in 2004 and
the modified program would remain. Only credits banked under the
modified program could be used in 2004 and later. EPA is proposing to
end the current program with the 2003 model year because of concern
that manufacturers could generate enough credits under the current
program to significantly delay the 2004 standards. The current program
allows manufacturers to earn credits up to the current NOX
standard of 4.0 g/bhp-hr. With most engines currently certified with
NOX levels below 2.0 g/bhp-hr, there is potential for
substantial credit generation without the application of improved
technology under the current ABT program. If manufacturers were to bank
these credits, they could potentially use them to delay the
introduction of engines meeting the 2004 standards for a large majority
of their sales for up to three years. The proposed 2.0 g/bhp-hr ceiling
for credit generation in the modified program provides opportunity for
manufacturers to earn credits through the use of emissions controls
that are superior to the average controls currently being used. EPA
believes this approach is consistent with the goals of ABT. EPA
requests comment on the proposed 2.0 g/bhp-hr ceiling and on other
alternatives for transitioning from the current 4.0 g/bhp-hr
NOX standard to the 1.0 g/bhp-hr NOX standard
proposed for 2004. One such alternative could be a phase down of the
credit generation trigger value during the model years prior to 2004,
rather than a single trigger point of 2.0 g/bhp-hr.
The changes to credit life and discounting being proposed for Otto-
cycle engines are conceptually consistent with the modifications
finalized for diesel engines. EPA is proposing to discount credits by
10 percent if the engine has an FEL above a certain value or cut-point.
EPA adopted cut points in the diesel program in order to identify the
introduction of new technology as opposed to recalibrating or enhancing
existing technology. EPA believes that adoption of cutpoints in the HD
Otto-cycle engine program will provide similar technology forcing
incentives. EPA selected cut-point levels which represent a clear step
in emissions control rather than a marginal emissions reduction. The 10
percent discount selected for the HD Otto-cycle engine ABT program is
consistent with the program finalized for diesel engines. In that final
rule, EPA noted that a 10 percent discount strikes a balance between
zero (which significantly reduces the incentive to develop and
implement significantly cleaner technology) and 20 percent (which
manufacturers indicated in comments was far too large and would create
a disincentive for the introduction of cleaner technology). (See 62 FR
54708, October 21, 1997.) EPA requests comment on the selected levels
of the cut-points and discount adjustment, including comments on
whether a phased-in approach with a decreasing cut-point would be
appropriate for this category of engines.
For diesels, EPA removed the three year credit life limit which
allows manufacturers to earn credits to be used in 2004 and later as
early as the 1998 model year. For Otto-cycle engines, MY 2000 will be
the earliest model year in which the rule would be effective due to the
timing of the rulemaking. Removing the credit life limit will provide
an additional year of potential credit banking and allows manufacturers
to retain credits after 2004 rather than having them expire after a
certain year. We believe that having credits expire would simply
encourage manufacturers to use the credits rather than save them; thus,
removing the credit life limit should provide a net environmental
benefit.50
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\50\ EPA presented a detailed analysis of its ABT program in the
Summary and Analysis of Comments for the Diesel Final Rule, Docket
A-95-27, document No. V-C-01.
---------------------------------------------------------------------------
We believe that our proposals detailed above for a modified ABT
program will encourage the early use of cleaner technologies and
provide manufacturers with valuable flexibility in transitioning to
more stringent standards. EPA is proposing the modification to the ABT
program in conjunction with the 1.0
g/bhp-hr NMHC+NOX engine-based standards to provide the
flexibility necessary to enable manufacturers to meet the standard
across their product line. This flexibility may not be necessary in the
context of a less stringent standard, in which case the proposed
modifications to the ABT program might not be supportable. EPA requests
comments on all aspects of the proposed ABT program.
D. Supplemental Exhaust Emission Standards and Test Procedures for HD
Diesel Engines
1. Introduction/Background
EPA's goal is to ensure real-world emissions control over the broad
range of in-use speed and load combinations that can occur, rather than
just controlling emissions under certain laboratory conditions. EPA's
1997 HD diesel rule was based on the expectation that this would be the
case. The 1997 rule's projected emissions benefit, expected control
technology, cost, and cost-effectiveness were derived with the
[[Page 58488]]
belief that the engines would be meeting the standards in-use under
typical operating conditions. The supplemental provisions we are
proposing today for HD diesel engines are intended to help ensure this
is the case. Today's proposal includes a new set of supplemental
emission standards and associated test procedures to more closely
represent the range of real world driving conditions.
EPA believes that an important tool for achieving an effective
compliance program is an in-use program with an objective standard and
easily implemented test procedure. Today's action does not include a
proposal for a manufacturer in-use testing program for HD diesels and
HD Otto-cycle engines. However, as discussed in section V, EPA believes
a manufacturer in-use testing program is a critical component of a
comprehensive compliance program, and EPA intends to work with
interested parties towards the development of a proposal for an in-use
testing program in the near future. We believe that the combination of
supplemental standards and an effective in-use testing program will
ensure that the environmental benefits resulting from the emission
standards for model year 2004 and beyond will be achieved in-use.
Historically, EPA's approach to emission standard setting has been
to set a numerical emission standard on a specified test procedure and
rely on the prohibition of defeat devices to ensure in-use control over
the range of operation not included in the test procedure. No single
test procedure can cover all real world operation or conditions,
particularly where certification is an engine-based test procedure
rather than a vehicle-based procedure (i.e., heavy-duty diesel engines,
heavy-duty Otto-cycle engines used in incomplete vehicles, and heavy-
duty Otto-cycle engines used in vehicles with a GVWR greater than
14,000 pounds). For example, the same engine used in both a 9,000 pound
and a 15,000 pound vehicle would likely see much higher speeds and
loads, on average, in the 15,000 pound vehicle. The defeat device
prohibition is designed to ensure that emissions controls are employed
during real world operation and not just under laboratory or test
procedure conditions. However, the defeat device prohibition is not a
quantified numerical standard and does not have an associated test
procedure. As a result, the current focus on a standardized test
procedure makes it harder to ensure that engines will operate with the
same level of control in the real world as in the test cell. To ensure
that emission standards are providing the intended benefits in use, the
Agency must have a reasonable expectation that emissions under real
world conditions reflect those measured on the test procedure. The
supplemental exhaust emission standards and test procedures for HD
diesel engines are designed to supplement the current FTP standards and
defeat device prohibition, and help ensure that the standards are
providing the intended benefits in actual use.
The Agency also believes a supplemental standard and test procedure
or an alternative mechanism is needed for HD Otto-cycle engines used in
incomplete vehicles, and heavy-duty Otto-cycle engines used in vehicles
with a GVWR greater than 14,000 pounds, in order to assure in-use
compliance over a broad range of operating conditions. Today's proposal
does not include supplemental standards for test procedures for this
class of engines because more information is needed to allow
determination of appropriate emission levels and resolution of other
specific technical issues. As discussed in section V, the Agency
intends to gather further information related to the appropriate levels
and scope of such standards over the next several months and to release
a subsequent proposal within the next year which would include
supplemental standards and test procedures for HD Otto-cycle engines.
In the Statement of Principles,51 signed by EPA, the
California Air Resources Board and engine manufacturers, the
signatories agreed to develop appropriate measures which ensure that
emission controls are maintained throughout the engine's life. During
the public comment period for the proposed 2004 standards for diesel
heavy duty engines, several state and environmental organizations
advocated establishing an in-use compliance program. (See 62 FR 54707-
54708; October 21, 1997). Commenters urged EPA to develop an effective
in-use compliance program to ensure that heavy-duty engines comply with
emission standards over their useful lives. We also received comment
that the current federal test procedure (FTP) does not reflect
realistic driving conditions (for example, high speeds and loads), and
that a more representative test cycle is needed. We acknowledged that
it was essential to further understand in-use emissions and establish a
comprehensive in-use compliance presence.
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\51\ For more background on the Statement of Principles, see
section III.A. of this preamble.
---------------------------------------------------------------------------
In the October 1997 final rule, EPA adopted a number of measures
designed to improve in-use compliance for heavy-duty diesel engines.
(See 62 FR 54700-54702; October 21, 1997). In summary, these measures
included: (1) Extending the engines' useful life; (2) increasing the
maintenance intervals for emissions-related components; (3)
strengthening the warranty provisions for emissions defects and
emission performance; (4) requiring that manufacturers provide owners
with guidance on maintenance for emissions-related components and on
responding to emission-related codes from on-board diagnostic systems;
and (5) strengthening ``anti-tampering'' requirements for engine
rebuilding. We also committed to further review and revise the
compliance programs if needed to ensure that the emission reductions
from more stringent standards are realized in-use. Since then, we have
learned that many heavy-duty engines currently are not meeting emission
standards in-use. EPA recently issued enforcement policy guidance to
partially address this problem.52
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\52\ Available in the public docket for review.
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2. Proposed Supplemental Test Procedures and Standards
We propose to add two supplemental sets of standards and test
requirements for HD diesel engines: (1) A supplemental steady-state
test and accompanying standards; and (2) Not-To-Exceed Limits. Like
current standards, these new standards would apply to certification,
production line testing, and vehicles in actual use. All existing
provisions regarding standards (e.g., warranty, certification, recall)
would be applicable to these new standards as well. The steady-state
test is proposed because it represents a significant portion of in-use
operation of heavy-duty diesel engines that is not adequately
represented by the FTP. In addition, we are proposing a third
supplemental test procedure for heavy-duty diesel engines--a Load
Response Test--as a data submittal requirement only; we do not propose
emission limits for this test procedure at this time. The proposed Load
Response Test also represents operation not adequately represented by
the current FTP (harder accelerations), and could eventually be used to
ensure effective control of NOX and PM during this type of
operation. The combination of these supplemental test requirements and
emission standards would provide assurance that engine emissions are
designed to achieve the expected level of in-use emissions control over
all expected operating regimes in-use. These test procedures and
emission limits are
[[Page 58489]]
described in greater detail in the following sections.
We believe that to ensure that emission standards actually achieve
their intended environmental benefits, the emissions measured during
engine test procedures must be indicative of emissions released during
real world operation. Recent advances in engine technology have created
the opportunity for a broader gap to exist between typical real world
operating conditions and those conditions represented by the current
EPA test cycle. The inconsistencies between lab and real world
emissions reduce the certainty that emission standards will achieve
their intended benefits. One approach to address this is enforcing
compliance with the current regulations, including the defeat device
prohibition, on a case-by-case basis. However, as discussed previously,
given the potential magnitude of the emission impact, we believe it is
more appropriate to address this concern through expanding the test
procedures and related emission standards.
As discussed in more detail in the following sections, each of
these supplemental proposed emission standards is expressed as a
multiple of the existing FTP emission standards, or Family Emission
Limit (FEL) if the engine is certified under the ABT program, whichever
is applicable. For example, the diesel engine NTE limit for
NOX + NMHC is 1.25 times the current FTP emission standard,
or 1.25 times the applicable FEL. When certifying engines under the ABT
program, manufacturers must ensure that the FEL is set sufficiently
high so that all of the new proposed emission standards will be met in-
use. For example, there may be cases where the FTP and supplemental
steady-state emission result is well below the standard, but setting
the FEL is constrained by the Not-To-Exceed emission result.
For purposes of certification, actual test data for the steady
state test and the Load Response Test would have to be submitted as
part of the certification application (although only the steady state
test data would require comparison to proposed emission limits). The
Not-to-Exceed test limits would require only a statement of compliance
at certification (with supporting details). The compliance statement
would need to state explicitly that the engine will comply with the
applicable NTE limits when operated under all conditions which may
reasonably be expected to be encountered in normal vehicle operation
and use. However, this statement must be founded upon emission test
data, additional technical information, and good engineering judgement.
The manufacturer's basis for making the compliance statement would be
explained within the certificate application documentation, and the
supporting information would be available for review by the Agency.
a. Supplemental Steady-State Test
We propose to add a steady-state test cycle to the current Federal
test procedures for HD diesel engines. The proposed steady-state test
cycle is consistent with the test cycle found in the European's ``EURO
III ESC Test''; however not all aspects of the proposed supplemental
steady-state test are identical to the EURO III ESC Test.53
Manufacturers would be required to meet the standards under this test
cycle as well as continuing to meet the standards using the current
test procedure (including the current transient test cycle) in 40 CFR
part 86, subpart N.54 The proposed supplemental steady-state
test cycle is needed so that the FTP reflects a greater range of
driving conditions experienced on the road. The current FTP does not
fully represent the driving patterns of today's heavy-duty diesel
vehicles, nor does it fully take into account the increased use of
electronic engine management systems. These electronic systems have the
ability to optimize fuel economy during real-world driving, but often
at the expense of emissions. The proposed steady-state test cycle
represents an important type of modern engine operation, in power and
speed ranges that are typically used in practice. The mid-speeds and
mid-to-high loads represented by the proposed steady-state test are the
speeds and loads that these engines are designed to operate at for
maximum efficiency and durability. Specifically, highway cruise speeds
and loads fall into the operation represented by the proposed steady-
state test.
---------------------------------------------------------------------------
\53\ ``Draft Proposal for a Directive of the European Parliament
and the Council Amending Directive 88/77/EEC of 3 December 1987 on
the Approximation of the Laws of the Member States Relating to the
Measures to be Taken Against the Emission of Gaseous and Particulate
Pollutants from Diesel Engines for Use in Vehicles'', a proposal
adopted by the Commission of the European Union on 3 December 1997,
for presentation to the European Council and Parliament.
\54\ These requirements are consistent with those in the Consent
Decrees recently signed with several heavy-duty diesel engine
manufacturers. (See 63 FR 59330-59334; November 3, 1998).
---------------------------------------------------------------------------
The proposed supplemental steady-state test cycle consists of 13
modes of speed and power, covering the typical operating range of
heavy-duty diesel engines. The cycle concentrates on the engine speed
range bounded by 50 percent and 70 percent of rated power, which is the
range most utilized by heavy-duty diesel engines. This speed range is
then divided into bands (engine speeds A, B and C, as defined in
proposed Sec. 86.1360-2004(c)). The ``control area'' is defined by the
area between engine speeds A and C, and between 25 to 100 percent load.
During the test cycle, the engine is initially run at idle speed, then
through a defined sequence of 12 modes at various speeds and engine
loads of 25, 50, 75 and 100 percent. Each mode (except idle) is run for
two minutes. During each mode of operation, the concentration of the
gaseous pollutants is measured and weighted (according to the weighting
factors in proposed Sec. 86.1360-2004(b)(1)). The weighted average
emissions for each pollutant, as calculated according to this steady-
state test procedure, must not be greater than 1.0 times the applicable
2004 emission standards. (See proposed Sec. 86.004-11(a)(3).)
Manufacturers would perform the supplemental steady-state test in
the laboratory following all applicable test procedures in 40 CFR part
86, subpart N (e.g., procedures for engine warm-up and exhaust
emissions measurement). The test must be conducted with all emission-
related engine control variables in the maximum NOX
producing condition which could be encountered for a 30 second or
longer averaging period at the given test point.
In addition to the 13 modes of the test cycle, EPA would have the
opportunity to select an additional three test points as a check to
ensure the effectiveness of the engine's emission controls within the
control area (e.g., ensuring that emissions do not ``peak'' outside of
the 13-mode test points). This requirement would ensure that an engine
achieves emissions control throughout the typical operating range. EPA
would notify the manufacturer of these three additional test points
prior to the test. During the test, the regulated pollutants would be
measured at each of these EPA-selected test points. The manufacturer
also would determine an interpolated value of pollutant emissions at
each EPA-selected test point, using the measured emissions of the
closest four adjacent test points. See the illustration in Figure 2 of
proposed Sec. 86.1360-2004(g). EPA proposes a four-point linear
interpolation procedure that is consistent with that of the European's
``EURO III'', referenced above. (See proposed Sec. 86.1360-2004(g)(2).)
The measured emissions value would then be compared to the interpolated
emissions value. The measured pollutant value must not exceed the
[[Page 58490]]
interpolated pollutant value by more than five percent. We request
comment on the proposed interpolation methodology and on whether five
percent is the appropriate value to use for comparison of interpolated
values and measured emissions.
The emission levels at the 12 non-idle test points and the
calculated emissions values from the four-point interpolation procedure
for intermediate test points would establish an emissions ``surface''
of Maximum Allowable Emission Limits (MAELs), as illustrated in Figure
1 of proposed Sec. 86.1360-2004(f). This surface would limit emissions
levels during all normal operations, including transient operation,
that occur within the control area defined above. Each point on this
surface will have a MAEL associated with it for all engines in that
engine family.55 The MAEL for each point is calculated using
the same four-point linear interpolation procedure used to determine
the emission value for the EPA test points discussed above. For
certification, production line and in-use engines, emissions generated
within the control area may not exceed the MAEL for the corresponding
speed and load point over a thirty second averaging period.
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\55\ The emissions surface would include all points in the
Supplemental Steady-State control area, as defined above.
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At certification, manufacturers would be responsible for testing
the MAELs by performing the ``check'' described above for the three
EPA-selected test points. Under its authorities in the Act, EPA could
determine compliance with the MAELs under any conditions that may
reasonably be expected to be encountered in normal vehicle operation
and use, either in the laboratory or in actual use (``on-road''), under
steady-state or transient conditions, and under varying ambient
conditions. (See section IV.D.3 for a discussion of on-road testing).
To determine compliance, test results from operation within the control
area must comply with the MAEL established for that engine family at
the same engine speed and load.
b. Not-To-Exceed Limits
To help ensure that heavy-duty engine emissions are controlled over
the full range of speed and load combinations commonly experienced in-
use, EPA is proposing to apply Not-To-Exceed (NTE) limits to HDDEs. The
NTE approach establishes an area (the ``NTE zone'') under the torque
curve of an engine where emissions must not exceed a specified value
for any of the regulated pollutants.56 The NTE standard
would apply under any conditions that could reasonably be expected to
be seen by that engine in normal vehicle operation and use. In
addition, we propose that the whole range of real ambient conditions be
included in NTE testing. The proposed NTE zones, limits, and ambient
conditions and test procedures for HDDEs and HDGEs are described below.
These requirements would take effect starting in the 2004 model year
and would apply to new engines as well as in use throughout the useful
life of the engine. We request comment on expanding the range of
ambient conditions in this manner and on whether this expanded range is
appropriate to begin with the 2004 model year, or whether a phased in
approach is more appropriate.
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\56\ Torque is a measure of rotational force. The torque curve
for an engine is determined by an engine ``mapping'' procedure
specified in the Code of Federal Regulations. The intent of the
mapping procedure is to determine the maximum available torque at
all engine speeds. The torque curve is merely a graphical
representation of the maximum torque across all engine speeds.
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In addition to helping to ensure emission benefits over the full
range of in-use operating conditions, the NTE requirements are also
expected to be an effective element of an in-use testing program. At
the time of certification manufacturers would have to submit a
statement that its engines will comply with these requirements under
all conditions which may reasonably be expected to occur in normal
vehicle operation and use. The manufacturer must provide a detailed
description of all testing, engineering analysis, and other information
that forms the basis for the statement. This certification statement
must be based on testing and/or research reasonably necessary to
support such a statement and on good engineering judgement. This
supporting information would have to be submitted to EPA at
certification upon request; manufacturers would not necessarily be
required to submit NTE test data for compliance during certification.
EPA believes that there are significant advantages to taking this
sort of approach for heavy-duty engines. The test procedure is very
flexible so it can represent most in-use operation and ambient
conditions. Therefore, the NTE approach takes all of the benefits of a
numerical standard and test procedure and expands it to cover a broad
range of conditions. Also, with the NTE approach, in-use testing and
compliance become much easier since emissions may be sampled during
normal vehicle use. A standard that relies on laboratory testing over a
very specific driving schedule makes it harder to perform in-use
testing, especially for engines, since the engines would have to be
removed from the vehicle. Testing during normal vehicle use, using an
objective numerical standard, makes enforcement easier and provides
more certainty of what is occurring in use versus a fixed laboratory
procedure.
Even with NTE requirements, EPA believes that it is still important
to retain standards based on the current heavy-duty engine test
procedure. This is the standard that EPA expects the certified engines
to meet on average in use. The NTE testing is more focused on maximum
limits on emissions for segments of operation or engines used in
certain applications or geographic regions and should not require
additional technology beyond what is used to meet the applicable FTP
standards. EPA believes that basing the emissions standards on a
distinct cycle and using the NTE zone to help ensure in-use control
creates a comprehensive program. The existing duty cycle includes low
speed and low torque operation that are not included in the NTE zone.
In addition, the standardized test cycle gives a basis for calculating
credits for use in the averaging, banking, and trading program.
The NTE requirements for heavy-duty diesel engines are proposed to
include other provisions including ambient temperature and humidity
ranges and corrections (discussed below). Start up conditions are
excluded from NTE testing because start-up is sufficiently covered by
the cold start in the FTP and would be expected to be significantly
higher than the proposed NTE limits for a short period of time.
The NTE test procedure could be run in a vehicle on the road or in
an emissions testing laboratory using an appropriate
dynamometer.57 The test itself does not involve a specific
driving cycle of any specific length (mileage or time), rather it
involves driving of any type that could occur within the bounds of the
NTE control area. The vehicle (or engine) would be operated under
conditions that may reasonably be expected to be encountered in normal
vehicle operation and use, including operation under steady-state or
transient conditions and under varying ambient conditions. Emissions
would be averaged over a minimum time of thirty seconds and then
compared to the applicable NTE emission limits. The
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applicable ambient conditions and the methodology for correcting
emissions results for temperature and/or humidity are described in the
following section. The proposed test procedure can be found in
Sec. 86.1370-2004 of the proposed regulations. We request comment on
this test procedure and its applicability to HD diesel engines,
particularly with respect to whether 30 seconds is an appropriate time
over which to average emissions for comparison to the emission limits
for HD diesel engines.
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\57\ Likewise, testing to determine compliance with the Maximum
Allowable Emission Limits could be conducted in the laboratory or in
a vehicle on the road.
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The definition of defeat device is being modified slightly to
account for the NTE limits. Under the previous definition of defeat
device, an auxiliary emission control device would not be considered a
defeat device if it reduced the effectiveness of the emission control
system under conditions that are substantially included in the federal
test procedure.
This definition is less appropriate for the NTE requirements. The
potential testing surface for the NTE encompasses much of the operating
range of the vehicle. Therefore, a definition of defeat device that
would exclude this testing surface would leave little area in which a
defeat device could be found. This, however, is not the intent of the
NTE. The NTE is not intended to be the primary emission limit on an
engine, but is intended instead as a ``no worse than this'' requirement
that puts an absolute high limit on emissions under most operating
conditions. It is not supposed to supplant the continuing obligation of
manufacturers to design their engines without defeat devices. Nor is it
supposed to provide a cushion for manufacturers to meet a less
stringent standard off the testing cycles. Therefore, EPA has revised
the definition of defeat device such that substantial inclusion in the
federal test procedure does not extend to the NTE zone.
The proposed NTE zone is illustrated in Figures 1 and 2. With the
exception of two limited regions under the torque curve (described
below), the NTE zone for diesels includes all engine operation at or
above 30 percent of the maximum torque value of the engine and all
engine operation at or above a specific engine speed calculated based
on the maximum power of the engine.58 This zone covers the
areas of operation that are of most concern to the Agency from an
environmental perspective. Because engines do not operate frequently at
speeds that occur below the maximum torque peak (heavy-duty diesel
engines generally operate at speeds near or above their maximum
torque), the emissions generated from operation at lower speeds are
relatively insignificant. The same is generally true of operation at
below 30 percent of maximum torque--heavy-duty diesel engines do not
spend much time in this region and the emissions generated in this
region of operation tend to be less of a concern for the Agency.
Manufacturers are still forbidden from using defeat devices both inside
and outside the NTE zone, however.
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\58\ The maximum torque value and maximum power of the engine
are derived as part of the engine mapping procedures specified in 40
CFR 86.1332.
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For the reasons described below, two small regions are excluded (or
``carved out'') from the NTE zone defined above. First, we propose to
exclude from the NTE zone the area under the torque curve that falls
below the curve representing 30 percent of the maximum power value of
the engine (as distinguished from maximum torque). This excluded region
contains low engine speed and torque operation for which we believe
current heavy-duty engines spend an insignificant portion of their
operating lives. In addition, at low loads and low-to-mid speeds (low
total power), the measurement of grams per brake-horsepower emissions
tends to balloon, even while emissions go down. This region is proposed
to be carved out for all pollutants.
Second, a PM-specific region is ``carved out'' of the NTE control
area. The PM-specific area of exclusion is generally in the area under
the torque curve where engine speeds are high and engine torque is low,
and can vary in shape depending upon several speed-related criteria and
calculations detailed in the regulations. Controlling PM in this range
of operation presents fundamental technical challenges which we believe
cannot be overcome in the 2004 time frame. Specifically, the cylinder
pressures created under these high speed and low load conditions are
often insufficient to prevent lube oil from being ingested into the
combustion chamber. High levels of PM emissions are the result.
Furthermore, we do not believe that these engines spend a significant
portion of their operating time in this limited speed and torque range.
The definition of the proposed NTE zone and the carve-out areas
strives to place an effective cap on emissions over a broad area of in-
use operation that includes the types of operation that are of the
greatest environmental concern. The definition of the control area, the
carve-outs, and the emissions limit must all be balanced to achieve the
Agency's goals. We believe that the combination of the proposed zone
and the proposed emission limits within the zone effectively accomplish
the Agency's goals of ensuring that emissions are controlled over a
wide range of in-use operation. We request comment on the proposed zone
and emission limits.
Examples of the NTE zone, including the areas excluded from the
zone, are shown below in Figures 1 and 2. The A, B, and C engine speeds
are the same as those defined for the advanced steady state test and
described above and in the proposed regulations. Note that there are
two possible constructions of the PM ``carve-out'' detailed in the
draft regulatory language. The example in Figure 1 shows the PM carve-
out as it would look if the C speed is below 2400 revolutions per
minute (rpm), while Figure 2 shows the construct of the PM carve-out if
the C speed is above 2400 rpm.
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Within the NTE zone, EPA proposes that emissions of each of the
regulated pollutants (NMHC+NOX, CO, PM), when averaged over
a minimum time of 30 seconds, must not exceed 1.25 times the applicable
FTP standards (or FEL if ABT is used). A minimum 30 second average is
proposed to ensure that a short transient does not produce high
results. This 30 second sampling period should be long enough to allow
an emissions spike to be averaged out while still retaining a short
enough period to look at a specific type of operation. In addition, EPA
proposes that within the NTE zone smoke and opacity must not exceed
either a filter smoke limit of 1.0 (on the Bosch smoke number scale) or
a thirty second average smoke opacity of four percent for a five inch
path for transient testing and a ten second average smoke opacity of
four percent for a five inch path for steady state testing.
c. Diesel Supplemental Load Response Test
Today we are also proposing a Supplemental Load Response Test (LRT)
for heavy-duty diesel engines. This supplemental test is intended to
represent a specific type of engine operation--rapid transient
acceleration--that is not adequately represented in the current
transient test procedure. Although the current transient test cycle
does contain numerous transient operations, these transients are
limited to the engine operating range exercised during the current FTP,
not the broader range of operation which is covered by the Supplemental
Load Response Test. Specifically, the Supplemental Load Response Test
is intended to address diesel engine emissions performance during rapid
transient accelerations from any speed within the NTE zone. As
proposed, the test focuses on quantifying PM and NOX
emissions during the portion of a truck's operation where it
accelerates rapidly and where certain engine emission controls can be
inadequate. In addition, this type of operation can often produce
visible smoke, which is frequently noticed by the public and can
influence their opinions about the cleanliness of diesel engines.
We are not proposing specific emission limits for this test
procedure at this time. Rather, we are proposing that manufacturers of
heavy-duty diesel engines submit test results as part of their
application for EPA certification. The test results to be submitted at
certification would include testing, at a minimum, at a several engine
speeds specified in the proposed regulations. As noted in section
III.D, the Consent Decrees with most of the heavy-duty diesel engine
manufacturers establish target limits for the Load Response Test of 1.3
times the FTP standard for NMHC+NOX and 1.7 times the FTP
standard for PM. We believe that these limits may be appropriate and
technologically feasible, but we also recognize that under the Consent
Decrees there is a process of data collection and evaluation that could
result in modifications to these limits sometime in the latter half of
the year 2000. The data submittal requirements proposed today are
consistent with the requirements in the Consent Decrees.
We believe that establishing a future Load Response Test with
appropriate emission limits may be a valuable addition to EPA's
compliance program, particularly for in-use on-road testing using the
equipment specified in a later section of this document, and when the
process of evaluating the available data is complete we intend to
evaluate the addition of specific Load Response Test emission limits to
EPA's compliance program in a future supplemental proposal. The
proposed data submittal requirement would enable a better understanding
of the emissions that occur under this type of operation and would
ensure that EPA establishes robust standards in a future action. Such a
future action would consider including a requirement that manufacturers
submit a statement of compliance at certification (similar to the
approach proposed today for the NTE emission limits). We request
comment on the proposed approach to a Load Response Test, as well as on
the possibility of adding appropriate emission limits and certification
requirements with a later action.
The test procedure as proposed is relatively straightforward. The
engine fuel control is moved rapidly to the full fuel position and held
at that point for a minimum of two seconds. As proposed, this sequence
would be carried out in a laboratory environment at a constant speed
setting, but in the future testing could be conducted using on-road
equipment specified in a following section, in which case the vehicle
speed would depend upon the characteristics and response of the vehicle
being tested. The proposed regulations specify six different speeds,
ranging from t
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