CALIFORNIA ENVIRONMENTAL PROTECTION AGENCY

AIR RESOURCES BOARD

STAFF REPORT: INITIAL STATEMENT OF REASONS

PROPOSED MODIFICATIONS TO THE PUBLIC TRANSIT BUS FLEET RULE

AND INTERIM CERTIFICATION PROCEDURES FOR HYBRID-ELECTRIC

URBAN TRANSIT BUSES

This report has been reviewed by the staff of the California Air Resources Board

and approved for publication. Approval does not signify that the contents

necessarily reflect the views and policies of the Air Resources Board, nor does

the mention of trade names or commercial products constitute endorsement or

recommendation for use.

Date of Release: September 6, 2002

Scheduled for Consideration: October 24, 2002
i

TABLE OF CONTENTS

EXECUTIVE SUMMARY................................................................................................1

I. INTRODUCTION......................................................................................................7

II. BACKGROUND .......................................................................................................9

A. URBAN BUSES AND EMISSION STANDARDS ...........................................................9

B. FEBRUARY 2000 URBAN TRANSIT BUS REGULATIONS .......................................11

C. IMPLEMENTATION OF THE URBAN TRANSIT BUS REGULATIONS ..........................13

D. THE ROLE OF HEBS IN CALIFORNIA ....................................................................15

E. NEED FOR MODIFICATIONS ...................................................................................19

III. SUMMARY OF PROPOSED REGULATIONS.................................................23

A. APPLICABILITY .......................................................................................................23

B. AMENDMENTS TO THE FLEET RULE, 1956.2 .......................................................24

C. HEB INTERIM CERTIFICATION...............................................................................30

IV. TECHNOLOGICAL FEASIBILITY......................................................................40

A. PM EMISSION REDUCTION TECHNOLOGY............................................................40

B. AVAILABILITY OF ULTRA LOW SULFUR DIESEL FUEL...........................................41

C. HEBS AND INTERIM CERTIFICATION.....................................................................43

V. ISSUES....................................................................................................................45

A. BUSES THAT SHOULD BE INCLUDED IN THE TOTAL DIESEL PM EMISSIONS

CALCULATION................................................................................................................45

B. BASELINE EMISSION YEAR THAT SHOULD BE USED............................................46

C. REQUEST FOR ALLOWING CREDIT FOR BUSES REBUILT/RETROFITTED USING A

CERTIFIED KIT UNDER THE U.S. EPA MANDATED PROGRAM....................................46

D. ALLOW ALL TRANSIT AGENCIES THE OPTION OF SWITCHING TO THE

ALTERNATIVE FUEL PATH .............................................................................................47

E. PROPOSED USEFUL LIFE, DURABILITY, AND EMISSIONS WARRANTY ARE TOO

STRINGENT TO ALLOW THE HEB TECHNOLOGY INTO THE MARKET PLACE ...............48

F. HEBS SHOULD BE VERIFIED FOLLOWING RETROFIT PROCEDURES..................48

G. CHASSIS TESTING MAY BE TOO COSTLY FOR MEASURING EXHAUST EMISSION

STANDARDS FROM HEBS.............................................................................................49

VI. REGULATORY ALTERNATIVES.......................................................................50

A. CHANGE PM RETROFIT SCHEDULE .....................................................................50

B. DECLINING PM FLEET AVERAGE .........................................................................50

C. INTERIM CERTIFICATION FOR HEBS FOLLOWING CHASSIS TEST PROCEDURE

WITHOUT EMISSION FACTOR RATIO.............................................................................51

D. CONTINUE ALLOWING 25 PERCENT EMISSION REDUCTION CLAIM WITHOUT

INTERIM CERTIFICATION................................................................................................52

VII. ECONOMIC IMPACTS .........................................................................................53

A. LEGAL REQUIREMENT...........................................................................................53

B. AFFECTED BUSINESSES .......................................................................................53
ii

C. POTENTIAL IMPACT ON BUSINESSES....................................................................53

D. POTENTIAL IMPACT ON BUSINESS COMPETITIVENESS ........................................54

E. POTENTIAL IMPACT ON EMPLOYMENT..................................................................55

F. POTENTIAL IMPACT ON BUSINESS CREATION, ELIMINATION, OR EXPANSION.....55

G. POTENTIAL COST TO LOCAL AND STATE AGENCIES............................................55

VIII. ENVIRONMENTAL IMPACTS, ENVIRONMENTAL JUSTICE, AND COSTEFFECTIVENESS .........................................................................................................56

A. AIR QUALITY BENEFITS.........................................................................................56

B. ENVIRONMENTAL JUSTICE ....................................................................................59

C. COST-EFFECTIVENESS .........................................................................................59

IX. SUMMARY AND STAFF RECOMMENDATION..............................................62

A. SUMMARY OF STAFF’S PROPOSAL.......................................................................62

B. STAFF RECOMMENDATION....................................................................................62

X. REFERENCES .......................................................................................................63

APPENDIX A: PROPOSED REGULATION ORDER

APPENDIX B: CALIFORNIA INTERIM CERTIFICATION PROCEDURES

FOR 2004 AND SUBSEQUENT MODEL HYBRIDELECTRIC VEHICLES, IN THE URBAN BUS AND HEAVYDUTY VEHICLE CLASSES

APPENDIX C: ORANGE COUNTY BUS CYCLE

APPENDIX D: REVIEW OF PM EMISSION REDUCTION TECHNOLOGY

APPENDIX E: URBAN DIESEL TRANSIT BUS EMISSIONS INVENTORY

APPENDIX F: STAFF ANALYSIS OF PM EMISSION REDUCTIONS AND

COST-EFFECTIVENESS
iii

TABLES AND FIGURES

Table 1 California and Federal NOx Emission Standards for

Urban Bus Engines .....................................................................................10

Table 2 California and Federal PM Emission Standards for

Urban Bus Engines .....................................................................................10

Table 3 Existing California Required and Optional, ReducedEmission Standards for Urban Bus Engines...........................................11

Table 4 PM Retrofit Requirements By Fuel Path..................................................12

Table 5 Proposed Compliance Schedule for Total Diesel PM

Emission.......................................................................................................25

Table 6 Transit Agencies in the SCAQMD on the Diesel Fuel Path..................27

Table 7 Transit Agencies Eligible for Fuel Delay..................................................42

Table 8 Statewide Transit Bus PM Inventory Scenarios .....................................58

Table 9 Average Cost-Effectiveness ......................................................................60

Figure 1 NOx Emission Results from HEBs ...........................................................17

Figure 2 PM Emission Results from HEBs .............................................................18

Figure 3 Example of Emission Factor Ratio Calculations.....................................33

Figure 4 Comparison of PM Emission Scenario ....................................................58
1

STAFF REPORT: INITIAL STATEMENT OF REASONS

PROPOSED MODIFICATIONS TO THE PUBLIC TRANSIT BUS FLEET RULE

AND INTERIM CERTIFICATION PROCEDURES FOR HYBRID-ELECTRIC

URBAN BUSES

EXECUTIVE SUMMARY

A major goal of the Air Resources Board (ARB or “the Board”) is to provide clean,

healthful air to all the citizens of California. California’s commitment to providing

clean public transportation is an important part of achieving this goal. Public

transportation provides important societal benefits. It provides access to work

and education, reduces congestion, and meets the mobility needs of the public,

including the elderly and physically challenged. However, urban transit buses,

one of California’s modes of public transportation, are also a source of oxides of

nitrogen (NOx) and diesel particulate matter (PM). NOx contributes to the

atmospheric formation of ozone and fine particles. Diesel PM has been identified

as a toxic air contaminant – a cancer-causing pollutant. These emissions often

occur within California’s most populated urban areas. It is vital to all Californians

that the ARB continue its efforts to reduce NOx and PM emissions from all

sources, specifically transit vehicles which transport California citizens every day.

In February 2000 the Board confirmed its continued commitment toward

improving emissions from public transportation by approving the “Public Transit

Bus Fleet Rule and Emission Standards for New Urban Buses.” The multifaceted transit bus regulations set fleet requirements applicable to transit

agencies, and set more stringent mid- and long-term emission standards for new

urban bus engines, applicable to manufacturers. Transit agencies were required

to choose between diesel or alternative fuel compliance paths. The fuel path

selected would determine the compliance schedule and reporting requirements.

The fleet rule was designed to provide transit agencies with flexibility in meeting

the NOx standard while achieving near-term PM reductions and promoting

advancement of PM control technology. The PM standard required transit

agencies to retrofit progressively newer model-year buses in their fleets with

devices capable of reducing PM emissions by 85 percent.

Recognizing the progressive nature of the fleet rule and emission standards, the

Board required staff to report back on the progress made by transit agencies

toward implementing the regulatory requirements. Since adoption of the rule,

staff has worked closely with transit agencies, urban transit bus and engine

manufacturers, and control technology manufacturers. Staff conducted three

workshops and several stakeholder’s meetings, attended industry meetings, and

issued written memoranda and advisories to the transit agencies. Staff gave

progress reports to the Board on September 20, 2001, and March 21, 2002.

Working together we have ensured that the vast majority of transit agencies will

be in compliance with the NOx fleet average requirements. Staff reported,
2

however, that PM retrofit technology capable of reducing PM emissions by the

mandated 85 percent or more would not be available for the 1993 model-year

and older engines in time to meet the first implementation deadlines.

Understanding the importance of maintaining the PM emission reductions

anticipated in the February 2000 public transit bus rulemaking and recognizing

the lack of PM retrofit technology for older buses, the Board directed staff

through Resolution 02-16, to consider another approach for requiring PM

retrofits. The Board’s objective was to provide transit agencies with additional

flexibility while obtaining as close to the same reductions in diesel PM as would

have been achieved had the existing regulations been fully implemented. This

report describes staff’s proposed amendments to the February 2000 public

transit bus rule to implement the Board’s directive, along with the environmental

and cost impacts associated with the proposed modifications.

Staff also reported that a testing and certification protocol needed to be

developed and adopted to accurately assess the emissions from hybrid-electric

urban transit buses (HEBs). HEBs are a relatively new but promising technology

for urban transit buses that would provide transit agencies with another option for

reducing both NOx and PM emissions. Current heavy-duty certification and test

procedures are based on engine testing and do not accurately reflect, without

modifications, the vehicle emissions of a hybrid-electric drive system. This report

presents staff’s proposed interim certification procedures for HEBs.

Summary of the Amendments

PM Emission Reduction Proposal

As directed by the Board in March 2002, staff reviewed the technology available

to achieve the current PM retrofit requirements. Staff concluded that PM retrofit

technology capable of reducing PM emissions by 85 percent or more is not

currently available for 1993 model-year and older engines. The 85 percent

requirement was to go into effect during 2002 with 100 percent of pre-1991 urban

bus engines retrofitted by January 1, 2003. In order to provide transit agencies

with maximum flexibility in reducing PM emissions, yet still aggressively reduce

in-use PM emissions, staff proposes to amend the current rule which requires

transit agencies to retrofit a percent of its overall fleet for each model year. The

proposed amendments would require transit agencies to reduce PM by a

specified percentage based on total diesel PM emissions. The proposed

schedule to achieve a required percent of PM emission reductions is based on

the implementation dates of the original regulation’s implementation schedule

and on the fuel path selected.

The proposed amendments would require that a transit agency on the diesel path

reduce its overall diesel fleet PM emissions by 40 percent of its January 1, 2002

total diesel PM emissions baseline by January 1, 2004, with increasing
3

reductions through 2007. Transit agencies that selected the alternative fuel path

would also be required to reduce PM emissions from diesel-fueled buses

remaining in their fleets. Those agencies would be required to reduce PM

emissions by 20 percent by 2004, with increasing reductions through 2009. This

new proposal provides transit agencies with the flexibility to choose the control

methodology for achieving the required percentage reduction, rather than the use

of retrofit control technology. A transit agency may choose to reduce in-use PM

emissions by replacing buses with new buses, repowering buses with new

engines, purchasing alternative-fueled engines that are not required under

current requirements, or installing ARB-verified PM emission reduction

technology.

Fuel Path Change

The proposed amendments include a one-time allowance for a transit agency to

change its fuel path selection from diesel to alternative fuel, in response to the

Board’s request that staff consider allowing this change. After surveying transit

agencies and examining potential impacts of the proposed modification, staff

determined that minimal impact would result from allowing transit agencies on

the diesel path located in the South Coast Air Quality Management District

(SCAQMD) to make the change to the alternative fuel path. Some of these

transit agencies chose the diesel path, although SCAQMD Rule 1192 requires

them to purchase alternative fuel buses. Because these transit agencies are

already required to purchase alternative-fueled buses, allowing any of them to

change fuel path would not have an impact on the emission reductions

anticipated from the current regulation. Staff’s proposal is to limit the scope of

the fuel path change only to transit agencies in the SCAQMD. Based on the

transit agencies’ response to staff’s solicitation to declare a fuel path change

from diesel to alternative fuel, only transit agencies in the SCAQMD replied and

expressed interest in the change. A transit agency that wishes to change fuel

path must make a declaration of its intention by January 31, 2004, at the same

time as it makes its regular annual report.

Alternative Fuel Bus Purchase Provision for Diesel Path Transit Agencies

The certified emission level of an engine that a transit agency wishes to purchase

during 2004 through 2006 is dependent on the agency’s selected fuel path. The

current regulations require engines sold to transit agencies on the diesel path to

meet a 0.5 g/bhp-hr NOx standard. This standard applies whether the engine is

a diesel-fueled, dual-fueled, bi-fueled, or alternative-fueled engine. Staff does

not expect any full-sized alternative-fueled or diesel-fueled urban bus engines

certified to 0.5 g/bhp-hr NOx emissions to be available through 2006. Transit

agencies on the alternative fuel path are currently allowed to purchase

alternative-fueled engines meeting a 2.5 g/bhp-hr NMHC + NOx standard

through 2006.
4

To encourage and facilitate transit agencies on the diesel path to purchase

alternative-fueled engines, and to ensure that transit buses are available to be

purchased in the 2004 through 2006 time period, some flexibility is needed for

transit agencies on the diesel path. Staff proposes to have consistent emission

standards for all alternative-fueled buses in the 2004 through 2006 model years,

regardless of the fuel path chosen by the transit agency. Thus, all transit

agencies may purchase any certified alternative-fueled engines from 2004

through 2006.

Transit Agency Request for Delay

On occasion, transit agencies have requested delays to allow them to deviate

from the schedule because of financial hardship. Small transit agencies may

face unique situations and lack the ability to utilize some of the flexibility within

the regulations. In order to provide a mechanism whereby the Executive Officer

can hear exceptional requests and decide on the merits whether an

implementation delay is warranted, staff proposes adding a general provision that

would allow a transit agency with fewer than 20 buses to request an

implementation delay based on demonstrated financial hardship.

Modifications to Definitions

To clarify and update the transit bus regulation in response to stakeholder

inquiries, staff proposes to modify the definitions of “active fleet” and “alternative

fuel”, and to add definitions for “emergency contingency vehicle” and “spare bus”.

The most significant modification pertains to alternative-fueled engines.

Previously the definition precluded any use of diesel fuel. The proposed revision

will allow the use of a small quantity of diesel as a pilot ignition source only.

Repeal Certification Procedures for PM Retrofit Devices

The proposed amendments require that any device installed on urban buses to

meet the diesel PM reduction requirement be verified under the procedures

adopted therein. Currently, there are two procedures available to manufacturers

of diesel emission control strategies to certify technology. To ensure that all

manufacturers follow the same procedures and have the same warranty and inuse compliance requirements, it is necessary to repeal “California Certification

Procedures for PM Retrofit Devices for On-Road Heavy-Duty Diesel Vehicles”,

adopted November 22, 2000 and incorporated by reference in CCR title 13,

section 1956.2 (f) (7). These procedures would be replaced with those adopted

by the Board in May 2002: "Diesel Emission Control Strategy Verification

Procedure, Warranty and In-Use Compliance Requirements for On-Road, OffRoad, and Stationary Diesel-Fueled Vehicles and Equipment.” This modification

would have no impact on transit agencies or businesses because no

manufacturer has followed the certification procedures that were adopted

November 22, 2000.
5

Hybrid-Electric Bus (HEB) Certification Procedure

Hybrid-electric drive systems are emerging in the marketplace, offering lower

energy use and lower emissions. Part of the challenge in developing a

certification procedure for buses that use hybrid electric drive systems is

designing a method that quantifies the emission benefits of the drive system in

various HEB platforms.

Currently, manufacturers have one option for certifying an HEB – apply for

certification to ARB on a case-by-case basis. Current procedures are enginebased and an HEB would be certified at a level that does not represent actual

emission benefits of the HEB. Current engine-based certification test procedures

do not have a method of quantifying the amount of power provided by the electric

drive system incorporated into the HEB. Although recent ARB tests of HEBs

being demonstrated in California indicate substantial emission reductions, these

conclusions have been based on a few results and are not representative of all of

the types of HEB platforms that are available for commercialization. Hence, staff

believes it is appropriate to propose an interim certification procedure that better

represents HEB emissions, to be effective for three years. This would allow ARB

to work closely with manufacturers to determine whether modifications or more

appropriate requirements are warranted in future years.

The proposed interim certification procedure for determining compliance with the

urban transit bus emission standards, applicable to 2004 and subsequent modelyear hybrid-electric buses, is based on a modified version of the Society of

Automotive Engineers (SAE) Recommended Practice SAE J2711. This protocol

was developed to test the emissions of heavy-duty hybrid-electric vehicles using

a chassis dynamometer. The HEB’s certification value is determined through

calculations using chassis dynamometer test results and engine certification

values for both the HEB and a conventional drivetrain urban transit bus. ARB’s

procedures include a provision for chassis dynamometer testing of conventional

drivetrain urban transit buses to determine baseline emissions.

Environmental Impacts and Cost-Effectiveness

The proposed amendments achieve close to the same emissions reductions,

beginning in 2005, as the original regulations. Prior to 2005, the benefits will be

less than the original regulations. Two factors account for the rule relaxation in

the early years: the lack of technology to retrofit older engines now and the need

to provide transit agencies additional time to obtain funding to replace older

engines.

If approved, the proposed amendments will reduce PM emissions statewide in

2010 by approximately 180 lbs/day (33.4 tons per year). Estimated costs to

transportation planning agencies, commissions, and transit agencies would
6

remain similar (about $2.5 million) to the estimate in the February 2000

rulemaking. The cost-effectiveness during 2003 to 2009 would range from

$10.91 to $44.51 per pound of PM, with an average expected cost effectiveness

of $25.23 per pound reduced. The original regulation cost-effectiveness was

reported as $17.90 per pound of PM reduced, which is within the range

calculated for the proposed amendments.

The proposed amendments seek to balance the need to reduce diesel PM

emissions to the extent technologically feasible with the need of the regulated

entities for flexibility in achieving those reductions. The calculated benefits do

not include the value of health benefits associated with a reduction in exposure

the diesel PM, a toxic air contaminant.

Recommendations

The ARB staff recommends that the Board adopt the proposed amendments and

incorporated test procedures. The new amended provisions will continue to

require that PM emissions from urban transit buses be reduced, while providing

transit agencies with additional flexibility. This proposal continues California’s

commitment to provide reductions of NOx and PM emissions from urban transit

buses.
7

I. INTRODUCTION

California’s air quality has improved significantly over the last thirty years, yet

there is a need to continue establishing and implementing regulatory and

incentive programs that are designed to achieve future air quality goals and

provide healthful air to all Californians. Over 90 percent of Californians still

breathe air that violates one or more health-based air quality standards.

Mobile source control and incentive programs have been innovative and

progressive and are vital to the attainment of air quality standards. Mobile

sources account for about 60 percent of ozone precursors and about 40 percent

of combustion particulate matter (PM) emissions, statewide. Mobile source

diesel engines account for 30 percent of the particulate emissions. ARB

identified diesel PM as a toxic air contaminant in 1998. Hence, the control of PM

for diesel-fueled engines is critical.

With this in mind, in February 2000 ARB adopted new regulations establishing a

public transit bus fleet rule and emission standards for new urban buses. These

regulations promote advanced technology for urban buses that will result in

significant reductions in NOx and PM emissions. The requirements were

designed to reduce NOx, an ozone precursor, and PM by encouraging transit

agencies to voluntarily purchase cleaner alternative fuel buses and to incorporate

ARB-certified PM retrofit traps on urban bus engines.

Recognizing the progressive nature of these regulations, the Board required staff

to report back regularly on the progress for implementing the regulatory

requirements and to consider developing a test procedure to certify hybridelectric urban transit buses (HEBs) – an evolving propulsion system for urban

transit buses. As such, staff worked closely with transit agencies to encourage

compliance with the requirements and reported back to the Board at its

September 20, 2001 and March 21, 2002 meetings. Based on staff’s reports, the

vast majority of the transit agencies will meet the NOx fleet average

requirements. However, PM retrofit technology for early model-year urban transit

buses would not be available for transit agencies to comply with the PM

requirements.

Understanding the importance of reducing PM, the Board directed staff through

Resolution 02-16 to consider another approach for reducing diesel PM while still

obtaining similar PM benefits as achieved in the current adopted urban transit

bus regulations. The Board also directed staff to consider an approach for

allowing transit agencies that selected the diesel fuel path to change to the

alternative fuel path, thus encouraging more PM reductions. The Board directed

staff to present the proposed modifications to the urban transit bus fleet rule
8

requirements in the fall of 2002, while also presenting proposed

recommendations for certifying HEBs.

This proposal contains ARB’s proposed amendments to the Public Transit Bus

Fleet Rule and Emission Standards for Urban Buses. The proposed

amendments are designed to provide transit agencies with greater flexibility to

comply with the required emission standards while recapturing the PM emission

reductions lost because of the lack of verified technology to meet the mandated

85 percent reduction. The most significant modifications include proposed

amendments that require transit agencies to reduce overall diesel PM emissions

through use of a variety of mechanisms, rather than through the use of one

method, a retrofit with a diesel particulate filter. Other proposed amendments

include: a method for allowing transit agencies in the South Coast Air Basin to

change from the “diesel” path to the “alternative fuel” path; a mechanism for a

transit agency to request a delay with compliance due to financial hardship; and

modifications to definitions for clarification of current regulations. This proposal

also includes proposed procedures for interim certification of HEBs.
9

II. BACKGROUND

This chapter provides a brief overview of California’s current regulations

designed to reduce emissions from urban transit bus engines. The chapter also

presents a brief overview of implementation and the need to modify current

regulations to ensure PM reductions, as anticipated from adoption of the

February 2000 Public Transit Bus Fleet Rule, are achieved.

A. Urban Buses and Emission Standards

In general, urban buses are owned or leased by public transit agencies that

receive federal, state, and local funds to subsidize new bus purchases and to

operate and maintain their bus fleets and facilities. Urban buses usually operate

in heavily populated areas, with a typical route consisting of stops and starts as

passengers are routinely picked up and delivered to their destinations.

Commuter bus operation within metropolitan areas (such as the YoloSacramento metropolitan area) that consists of more than a few pick-up and

drop-off stops is considered to fall within the definition of urban bus operation.

Urban buses are generally 35 to 40 feet long, are normally powered by a heavy

heavy-duty diesel engine; and fall within the heavy heavy-duty vehicle

classification of greater than 33,000 pounds gross vehicle weight (GVW). The

ARB staff estimates that there are about 9,100 full-size transit buses operating in

California in 2002. Of these, approximately 80 percent are operated by the 18

largest transit fleets with more than 100 buses in their fleet. The remaining

buses are spread among 50 other transit agencies that operate urban buses

throughout California.

Urban buses have relatively high emissions (on a per vehicle basis) of NOx and

PM. Based on ARB’s most current emission inventory model, urban buses will

emit 8 tons per day of NOx and a half ton per day of PM in 2005. NOx is critical

because it is one of the major components of ozone formation. Diesel particulate

matter has been identified as a toxic air contaminant because it increases the

risk of lung cancer, increases the onset and severity of respiratory and cardiac

diseases, and increases mortality. Diesel engines emit relatively low levels of

other pollutants, such as hydrocarbons (HC), and carbon monoxide (CO).

Tables 1 and 2 below list both California and federal NOx and PM emission

standards for urban bus engines.
10

Table 1

California and Federal NOx Emission Standards for Urban Bus Engines

(g/bhp-hr)

Model Year California Federal

1988 6.0 10.7

1990 6.0 6.0

1991 5.0 5.0

1996 4.0 5.0

1998 4.0 4.0

October 2002 2.0(1)(2) 2.0(1)(2)

2004 0.5(3) --

2007 0.2 0.2

1. Nominal NOx level based on U.S. EPA and ARB emission standards of 2.4 g/bhp-hr NOx plus non-methane

hydrocarbons (NMHC) or 2.5 g/bhp-hr NOx plus NMHC with 0.5 g/bhp-hr NMHC cap to take effect in October 2002.

2. For those engines subject to the Settlement Agreements between the heavy-duty engine manufacturers, the U.S.

Environmental Protection Agency, and ARB. As part of the Settlement Agreements, the federal and state heavy-duty

engine emission standards adopted for 2004 are to take effect in October 2002.

3. Standard applies to urban buses for fleets that have selected the diesel path, whether equipped with diesel-fuel, dual

fuel, bi-fuel, or alternative fuel engines.

Table 2

California and Federal PM Emission Standards for Urban Bus Engines

(g/bhp-hr)

Model Year California Federal

1988 0.6 0.6

1991 0.1 0.25

1993 0.1 0.1

1994 0.07 0.07

1996 0.05(1) 0.05(1)

October 2002 0.01 0.05

2007 0.01 0.01

(1) In-use standard of 0.07 g/bhp-hr.
11

In addition to the mandatory emission standards listed above, the ARB also has

optional, reduced-emission standards, which were integrated into the

February 2000 urban transit bus fleet rule. The optional reduced-emission

standards for NOx are listed in Table 3, below.

Table 3

Existing California Required and

Optional, Reduced-Emission Standards for Urban Buses

(g/bhp-hr)

Model Year Primary Standard Optional

Standards

Increment

2000 - 10/2002 4.0 (NOx) 2.5 – 0.5 0.5

10/2002 – 2003 2.4 NOx+NMHC

or

2.5 NOx+NMHC with

0.5 NMHC cap

1.8-0.3 0.3

2004 – 2006a2.4 NOx+NMHC

or

2.5 NOx+NMHC with

0.5 NMHC cap

1.8-0.3 0.3

Notes: a. Emission standards apply to alternative fueled engines on the alternative fuel path.

B. February 2000 Urban Transit Bus Regulations

Urban Transit Bus regulations were approved by the Board in February 2000.

This regulation contains two elements to reduce emissions from urban buses:

1) a multi-component transit bus fleet rule applicable to transit agencies that

ultimately requires zero-emission bus (ZEB) purchases beginning in 2008; and

2) more stringent emission standards for engines used in urban buses,

applicable to engine manufacturers.

The fleet rule was designed to provide transit agencies with flexibility in meeting

the NOx standard while also achieving very near-term PM benefits and

progressively promoting advanced PM control technology for California’s urban

transit buses. The engine standards were designed to achieve long-term

emission benefits resulting from new bus engines. In order to provide agencies

with flexibility in complying with the standards, transit agencies were required to

choose between two fleet rule compliance paths -- the “diesel” path or the

“alternative fuel” path.
12

1. Requirements for PM

Based on the need for PM emission reductions, California set technology-forcing

PM emission standards for new engines. Beginning with engines produced after

October 1, 2002, new engines used in urban transit buses must meet a 0.01

g/bhp-hr PM standard. In order to comply with these standards by the end of

2002, however, staff was aware that advanced fuel and control technology, such

as ultra low sulfur (<15 ppm) fuel, and diesel particulate filters (DPFs) would be

necessary.

Staff’s approach was to include requirements that reduce in-use PM emissions

from older diesel engines used in urban transit buses. In order to enable the use

of PM-reducing technology and also obtain some reductions in diesel PM

immediately, transit agencies on both paths were required to use ultra low-sulfur

fuel as of July 1, 2002. Use of ultra low-sulfur fuel would facilitate use of DPFs, a

technology likely needed to meet future PM standards. In addition, by

January 1, 2003, and through 2009, transit agencies must retrofit their in-use

diesel fuel, dual fuel, bi-fuel and diesel HEB engines produced through October

1, 2002, with ARB-verfied devices that reduce PM by 85 percent or more. The

only current technology that can achieve this level of control is the DPF. The

compliance path selected would determine the model years affected, percent of

the fleet retrofitted, and the date for compliance. Table 4 lists the compliance

schedule for PM retrofits that is in the original rule.

Table 4

PM Retrofit Requirements By Fuel Path

Diesel Path Alternative Fuel Path

Tier 1 (pre 1991)

100% by January 1, 2003

Tier 1 (pre 1991)

100% by January 1, 2003

Tier 2 (1991 - 1995)

50% by 1/1/03

100% by 1/1/04

Tier 2 (1991-1995)

20% by 1/1/03

75% by 1/1/04

100% by 1/1/05

Tier 3 (1996 - pre-Oct. 2002)

20% by 1/1/05

75% by 1/1/06

100% by 1/107

Tier 3 (1996 – pre-Oct. 2002)

20% by 1/1/07

75% by 1/1/08

100% by 1/1/09
13

2. Anticipated Emission Reductions

Staff estimated that the new low-emission standard and ZEB requirements would

result in about 5.4 tons per day (tpd) NOx and 0.04 tpd (50 lbs/day) PM

emissions reductions in 2010. The PM retrofit component of the February 2000

fleet rule would provide California with a PM emissions benefit of about

300 lbs/day in 2005, and 100 lbs/day in 2010. Requiring PM retrofits for older

model-year engines is important in order to achieve significant and much needed

PM emission reductions early.

C. Implementation of the Urban Transit Bus Regulations

Staff has reported back to the Board on a regular basis on implementation

progress by transit agencies. The Board asked staff to report: (1) on the transit

agency program; (2) on implementation of NOx emission reduction strategies as

an alternative to compliance with the 2004 standards along with an analysis of

the first exemption application and a recommendation; (3) on the status of the

advanced aftertreatment systems; and (4) on progress and development of a test

procedure for HEBs. ARB staff has presented the Board with its first and second

updates on September 20, 2001, and March 21, 2002. Staff has also worked

with industry to develop the appropriate test procedure for certification of a

hybrid-electric urban transit bus. This section provides a brief overview of the

status on implementation and compliance with the February 2000 rulemaking for

urban transit buses.

1. PM Retrofit Requirements

The approach for reducing PM relied heavily on the availability of DPFs for the

older model-year urban transit bus engines beginning in 2003. At the time the

public transit bus fleet rule was adopted, experience with DPFs was limited but

promising. Demonstration programs using DPFs on a variety of engines showed

promise for incorporation of this technology on all vehicles -- including older

vehicles. Hence the 2000 Urban Transit Bus Fleet Rule required that 100

percent of pre-1991 diesel engines used in urban transit buses be retrofitted with

ARB certified PM retrofits by January 1, 2003. Furthermore, the PM retrofit must

reduce PM emissions by a minimum of 85 percent. Staff focused the original

regulations on retrofitting the oldest engines first, even though they were more

technologically challenging, because these were the engines with the highest PM

emissions.

After the rules were adopted, staff worked closely with transit agencies and

manufacturers to determine compliance with the approved PM retrofit

requirements. Staff analyzed the status of PM retrofit technology and, by
14

March 2002, concluded that it was unlikely that retrofit technology for the oldest

engines would be made available by manufacturers within the next year, or even

in the near future. The only technology that will reduce PM emissions by 85

percent or more, as required, is the DPF. ARB staff had verified two DPF

systems for use in 1994 and newer engines, but the DPF manufacturers had

indicated that they would not be verifying technology in the near future for pre1994 and any two-stroke engines.

The major issues preventing the use of this technology include very high in-use

PM emissions from the older transit bus engines, which clogs diesel particulate

filters rapidly, and low exhaust emission temperatures from two-stroke engines,

which inhibit regeneration of DPFs. Another major issue that may prevent

development of a new technology for these older engines is the small and

declining number of older, two-stroke engines remaining in the transit bus fleet,

which makes it less likely that manufacturers will invest in research and

development to bring feasible technology to market. Indeed, the major

manufacturers have shown little interest in developing technology for the oldest

engines.

Based on these findings, staff reported to the Board on March 21, 2002, that

currently there are no ARB-verified PM retrofits available for pre-1994 engines

that would reduce PM by 85 percent. Hence, transit agencies would not be able

to comply with current requirements by January 2003. The Board responded by

directing staff, in Resolution 02-16 (March 21, 2002), to make the necessary

changes to the diesel PM retrofit implementation schedule to recapture the diesel

PM emission reductions lost because of the unavailability of technology. The

ultimate goal for a new proposal would be to achieve as close to the same

reductions in diesel PM as feasible, when compared to the PM reductions that

would have been achieved had the existing regulation been fully implemented.

2. Selecting a Fuel Path

Under the current Public Transit Bus Fleet Rule, transit agencies were also

required to declare an irrevocable fuel path – alternative fuel or diesel fuel – by

January 31, 2001. The fuel path selected would determine the fraction of new

bus purchases required to be alternative-fueled, and the compliance dates for

incorporating PM retrofits and purchasing ZEBs. For example, for a transit

agency on the alternative fuel path 85 percent of all new purchases must be

alternative fuel buses. However, under this path transit agencies are provided

with two years additional time to meet the PM retrofit, and ZEB purchase

requirements.

During the March 2002 update to the Board, witnesses testified in favor of

allowing transit agencies to change their fuel path selection from diesel to

alternative fuel. Recognizing the benefits of alternative fuel technology, the
15

Board directed staff to evaluate the impact of allowing a transit agency to change

its fuel path selection and make a recommendation.

3. HEB Test Procedures

Staff has also been working with industry to develop an interim certification

procedure for hybrid-electric buses. Without a certification procedure in place,

transit agencies planning to purchase HEBs as part of their fleet would not have

a method for determining full emission benefits from the hybrid-electric

technology. To allow transit agencies to receive emission reduction credit from

the use of hybrid-electric buses, prior to the adoption of a certification procedure,

ARB’s Executive Officer established that HEBs would receive emission

certification values 25 percent below the urban bus engine certification standard.

A brief description of the proposed interim certification procedures for hybridelectric urban buses is presented in Chapter III. The detailed interim certification

procedure is provided in Appendix B of this document.

D. The Role of HEBs in California

Hybrid-electric propulsion systems combine two motive power sources: an

energy storage system such as a battery pack, and an internal combustion

engine, turbine or fuel cell functioning as an auxiliary power unit (APU). An

electric motor provides partial or complete power to the wheels. In addition,

energy otherwise lost as heat during braking is captured through regenerative

braking to charge the energy storage system. Since the engine/turbine/fuel cell

is not the sole power source in hybrid-electric drivetrains, a smaller engine can

be used and is operated at high efficiency and low emissions. Transit buses and

delivery trucks with frequent stop-and-go drive cycles are ideal for hybrid-electric

applications. The energy storage system is used during periods of initial

acceleration which are usually high emission episodes, and regenerative braking

during frequent stops will charge the energy storage system.

Current requirements under the Public Transit Bus Fleet Rule and future urban

bus emission standards in California have been designed to encourage

advanced technology in buses. Hybrid-electric drive systems provide another

viable option to reduce NOx and PM emissions from urban transit buses and

heavy-duty vehicles operating in California. Emissions testing results from HEBs

(presented in section 3) indicate that these buses can potentially meet the future

more stringent urban bus standards. If certified to full emission benefits, HEBs

may be purchased to meet upcoming regulatory requirements, and potentially

future more stringent requirements.
16

1. HEB Available Technology

Hybrid-electric drive systems for urban transit buses have been available

commercially for five years. Within this time, a number of engine and turbine

configurations have been developed. HEBs are available with internal

combustion engines fueled with diesel, CNG, propane, or gasoline. Turbines

fueled with diesel, CNG or liquefied petroleum gas (LPG) are also used in urban

buses equipped with hybrid-electric drive systems. Fuel cell HEBs will be

available in the near future.

Current hybrid-electric drive systems for urban transit buses use battery packs

for energy storage. Energy storage systems using ultracapacitors or flywheels

are under development. It is anticipated that hybrid-electric drive system

technology will continue to advance at a rapid rate.

2. HEB Demonstration Programs

New York City Transit was the first North American transit agency to demonstrate

full-size HEBs in revenue service. The program started in 1998 with four diesel

HEBs; an additional six diesel HEBs were added in 2000. The favorable results

from this initial study resulted in plans for delivery of an additional 375 diesel

HEBs over the next four years.

A number of transit agencies are conducting small HEB demonstration projects in

California. HEBs are in operation in Fresno, Los Angeles, Orange County,

San Bernadino, San Francisco, and Torrance. Additional transit agencies in

California have indicated an interest in purchasing HEBs for their fleets in the

future.

3. Development of Heavy-Duty Hybrid-Electric Vehicle Test Procedures

Heavy-duty vehicles are currently certified using an engine test procedure, which

cannot reflect the emission benefits provided by a hybrid-electric drive system. A

new testing method for exhaust emissions from heavy-duty hybrid-electric

vehicles needed to be developed. ARB staff participated with members from

industry, academia, and government in the Northeast Advanced Vehicle

Consortium (NAVC) Heavy-Duty Hybrid Certification Work Group to establish

draft heavy-duty hybrid-electric vehicle test procedures. SAE, collaborating with

the Heavy-Duty Hybrid Certification Work Group, developed a heavy-duty hybridelectric chassis testing protocol, SAE J2711, based on the light-duty hybridelectric chassis testing protocol J1711. This proposed recommended practice

has received final approval by SAE through a balloting process in April 2002.
17

4. Emissions Testing of HEBs

The proposed (now approved by SAE as a recommended practice) chassis test

procedure has been used for emission testing of a limited number of HEBs and

conventional drivetrain buses. The test results illustrated in Figures 1 and 2, on

the following page, were compiled from studies conducted in four testing facilities

over the past three years. The model year of each bus is listed with

manufacturer and fuel for each HEB, model years are indicated for the

conventional drivetrain buses. All buses are 40-foot platforms except for the

E-bus turbine LPG hybrid. Currently, the only data available for buses that utilize

turbines pertains to a 22-foot platform and is included in these figures. Examples

of older and newer diesel hybrid technology are provided for two manufacturers,

Allison Electric Drives and BAE SYSTEMS. The diesel HEBs all utilize diesel

particulate filters; the gasoline HEB has a catalytic converter.

Figure 1: NOx Emission Results from HEBs

0

5

10

15

20

25

30

35

typical 1999

Diesel

typical 1999

CNG

Allison ED

1999 diesel

hybrid

Allison ED

2000 diesel

hybrid

BAE

SYSTEMS

1998 diesel

hybrid

BAE

SYSTEMS

2001 diesel

hybrid

E-bus 2000

turbine LPG

hybrid

ISE Research

2001 gasoline

hybrid

g/mile

Diesel Bus

CNG Bus

HEBs
18

Figure 2: PM Emission Results from HEBs

It is important to understand that chassis testing provides results in units of

grams per mile instead of g/bhp-hr used for engine certification. However, NOx

emissions results for the diesel HEBs indicate about a 50 percent reduction over

emissions from the conventional diesel bus. Furthermore, the turbine LPG hybrid

and gasoline hybrid indicate a potential for much lower NOx emissions over the

diesel hybrids.

While limited test data is available to make statistical significant evaluations,

HEBs are considered a viable technology for reducing emissions from urban

transit buses. However, HEBs are rapidly changing, there are many

configurations and designs, and the available test data does not represent every

type of HEB available. For these reasons, staff is proposing an interim

certification procedure. The interim certification procedure would follow a

modified SAE J2711 in conjunction with a supplemental formula that would

calculate an emission factor ratio to determine a certification value in units of

g/bhp-hr. An interim test procedure would provide a method for testing HEBs

through which ARB staff would perform complete and comparable evaluations.

0

0.05

0.1

0.15

0.2

0.25

0.3

typical 1999

Diesel

typical 1999

CNG

Allison ED

1999 diesel

hybrid

Allison ED

2000 diesel

hybrid

BAE SYSTEMS

1998 diesel

hybrid

BAE SYSTEMS

2001 diesel

hybrid

E-bus 2000

turbine LPG

hybrid

ISE Research

2001 gasoline

hybrid

g/mile

Diesel Bus

CNG Bus

HEBs
19

E. Need for Modifications

1. PM Retrofit

During the March 2002 status update on the public transit bus rule making, staff

informed the Board that there were no DPFs verified for 1993 and older modelyear urban transit bus engines that would reduce PM emissions by 85 percent or

more. This is a problem because the rule requires transit agencies to retrofit

100 percent of their pre-1991 model-year engines by January 1, 2003, and

differing percentages of their 1991-1995 model-year engines, based on fuel path,

also by January 1, 2003, using devices that reduce diesel PM by 85 percent or

more.

The regulation allows ARB’s Executive Officer to grant one-year delays for

retrofitting because of unavailability of a retrofit device. After evaluating the

status of technology development, however, staff determined that technology to

reduce diesel PM by 85 percent or more from pre-1994 and two-stroke engines is

unlikely to be available even after one year, by January 1, 2004. Transit

agencies, therefore would be unable to comply with the PM retrofit requirements.

The Board directed staff to revise the current PM retrofit requirements and

consider another approach that would achieve as close to the same reductions in

diesel PM as feasible, when compared to PM reductions anticipated from full

implementation of the 2000 urban transit bus rule making.

2. Fuel Path Change from Diesel Path to Alternative Fuel Path

At its March 21, 2002 meeting, the Board heard testimony regarding the fuel path

selection by transit agencies. Under the regulation, transit agencies elected a

fuel path as of January 31, 2001, which may not be changed for the life of the

rule. Some transit agencies located in the SCAQMD have asked staff in the past

if they could change their fuel path, but the rule does not allow any change.

Witnesses at the March 21, 2002, meeting asked the Board to allow transit

agencies on the diesel path the option of changing to the alternative fuel path,

and the Board directed staff to analyze the impact of and need for such a

change.

3. Alternative Fuel Bus Purchase Provision for Diesel Path Transit

Agencies

The certified emission level of an engine that a transit agency wishes to

purchase, during 2004 through 2006, is dependent on the agency’s selected fuel

path. The current regulations require engines sold to transit agencies on the

diesel path to meet a 0.5 g/bhp-hr NOx standard, unless the transit agency has

an approved alternative NOx strategy exemption. This standard applies whether

the engine is a diesel-fueled, dual-fueled, bi-fueled, or alternative-fueled engine.
20

Staff does not expect, however, any full-sized alternative-fueled or diesel-fueled

urban bus engines certified to 0.5 g/bhp-hr NOx emissions to be available

through 2006. Transit agencies on the alternative fuel path are currently allowed

to purchase alternative-fueled engines meeting a 2.5 g/bhp-hr NOx+NMHC

standard through 2006.

To encourage and facilitate transit agencies on the diesel path to purchase

alternative-fueled engines, and to ensure transit buses are available to be

purchased in the 2004 through 2006 time period, some flexibility is needed. Staff

proposes to have consistent emission standards for all alternative fuel buses in

the 2004 through 2006 model years, regardless of transit agency fuel path.

4. Transit Agency Request for Delay

Staff has been asked periodically by transit agencies to allow them to deviate

from the schedule and delay implementation because of financial hardship.

Specifically, a small number of transit agencies, two or three, have requested a

compliance delay in meeting the July 1, 2002 ultra low sulfur (<15 ppm) fuel

requirement. One transit agency, for example, has two transit buses operating

on diesel fuel, which it plans to replace with natural gas buses in two years. This

transit agency does not have ultra low sulfur fuel available locally and would have

to build infrastructure (storage tanks), which it would use for only two years while

it is converting all of its fleet to alternative fuels. They have requested, therefore,

a two-year delay in complying with the ultra low sulfur diesel fuel mandate, after

which they will no longer have any buses operating on diesel fuel.

In some cases, staff has viewed the request for a delay favorably, yet is unable

to consider these requests because of the lack of any provision in the regulation

for dealing with variations from implementation. Staff has therefore proposed

adding a general provision that would allow a transit agency to request an

implementation delay because of financial hardship, and a mechanism by which

the Executive Officer could grant or deny the request.

5. Amended Definitions

Staff has determined that two modifications and two additions are needed to the

list of definitions. Staff proposes to modify the definition of “active fleet” and

define terms that are used in that definition. The modification is necessary to

improve clarity and to assure that terms agree more closely to the Federal

Transit Administration (FTA 2001) definitions. The two terms that must be

defined are “emergency contingency vehicles” and “spare buses.” Defining

these two terms is important because the term “active fleet” is used several times

in the rule to determine how many buses must be included when calculating, for

example, the NOx fleet average and which buses must be retrofitted to reduce

PM emissions.
21

In addition, staff has determined that the definition of “alternative fuel” needs to

be modified to clarify the classification of a new-technology engine which uses a

very small amount of diesel fuel for pilot ignition, but otherwise uses alternative

fuel for operation.

6. Repeal California Certification Procedures for PM Retrofit Devices

In the February 2000 rulemaking, the Board adopted "California Certification

Procedures for PM Retrofit Devices for On-Road Heavy-Duty Diesel Vehicles.”

These procedures were adopted to enable this technology to enter into

California’s market and transit agencies would have technology available to

comply with the PM retrofit requirements. In May 2002 the Board adopted the

"Diesel Emission Control Strategy Verification Procedure, Warranty and In-Use

Compliance Requirements for On-Road, Off-Road, and Stationary Diesel-Fueled

Vehicles and Equipment.” The proposed amendments require that any device

installed on urban buses to meet the diesel PM reduction requirement be verified

under the procedures adopted therein. Currently, there are two procedures

available to manufacturers of diesel emission control strategies to certify

technology. To ensure that all manufacturers follow the same procedures and

have the same warranty and in-use compliance requirements, it is necessary to

repeal “California Certification Procedures for PM Retrofit Devices for On-Road

Heavy-Duty Diesel Vehicles”, adopted November 22, 2000 and incorporated by

reference in CCR title 13, section 1956.2 (f) (7). This modification would have no

impact on transit agencies or businesses because no manufacturer has followed

the certification procedures that were adopted November 22, 2000.

7. Hybrid-Electric Bus Test Procedures

For heavy-duty engines, the U.S. EPA and ARB ensure maximum emission

reductions by adopting engine test procedures that measure emissions occurring

during typical in-use driving conditions. In order to sell an engine in California,

manufacturers must follow the federal/ARB regulatory test procedure and certify

engines to the appropriate regulatory standard or optional standard. Typically,

owners of heavy-duty vehicles powered by engines certified to the optional

standards are also eligible to receive either incentive funds or emission reduction

credits for operating vehicles that are cleaner than required.

Standards implemented beginning this month require NOx emissions from

heavy-duty vehicles and urban transit buses to be nearly 50 percent lower than

previous standards. Hybrid-electric drive systems have the potential to allow

urban transit buses to meet the already adopted urban transit bus standards and

future more stringent standards. This technology can also be used in other

heavy-duty vehicles to meet the future 2007 standards. However, test

procedures are needed to certify these systems in heavy-duty vehicles for sale in

California. At this time, there is not an approved certification procedure available

to certify full emission benefits of hybrid-electric drive systems. Current heavy-
22

duty vehicle certification is conducted using engine-based test procedures. As

hybrid-electric vehicles utilize both an electric motor and an internal combustion

engine, engine testing alone will not reflect the contribution of the electric motor,

or the emission benefits associated with it. Hence, there is need to develop a

methodology for determining the actual emission benefits provided by heavy-duty

hybrid-electric drive systems, specifically urban transit buses.
23

III. SUMMARY OF PROPOSED REGULATIONS

Staff recommends that the Board adopt proposed amendments to sections

1956.1, 1956.2, 1956.4, 1956.8, and 2112, title 13, California Code of

Regulations, and the incorporated “California Interim Certification Procedures for

2004 and Subsequent Model Hybrid-Electric Vehicles, in the Urban Bus and

Heavy-duty Vehicle Classes”, as set forth in Appendix A. All the provisions in the

proposed amendments and new test procedures apply to engines and vehicles

produced for sale in California. There are two components to this proposal 1) to

the urban transit fleet rule and 2) incorporation of the exhaust emission test

procedures for HEBs. The proposed amendments to the urban transit fleet rule

would provide transit agencies with additional flexibility in meeting the PM retrofit

requirement. The proposed amendments also include a one-time allowance for a

transit agency in the SCAQMD to change its fuel path selection from diesel to

alternative fuel and a method for ARB’s Executive Officer to grant transit

agencies a delay in compliance with the Public Transit Bus Fleet Rule. Finally,

staff is proposing modifications to clarify the definitions of an “active fleet” and

“alternative fuel bus”; and adding two new definitions -- “emergency contingency

vehicle”, and “spare bus.”

With this proposal, staff is proposing to incorporate exhaust emission test

procedures to certify HEBs for an interim period of three years. Since the

technology for HEBs is fairly new and rapidly evolving, staff will use the interim

period to determine the appropriateness of the proposed test procedures. Staff

proposes to present modifications to the Board after two years, if necessary.

A. Applicability

The current urban bus definition, as specified in Section 86.094-2 of Subpart N,

Part 86, title 40, CFR, is a passenger-carrying vehicle (+33,000 pound GVW)

powered by a heavy heavy-duty diesel-powered engine with a load capacity of

fifteen or more passengers and intended primarily for intra-city operation, or

operation within a metropolitan area. Equipment on urban buses usually

includes quick-opening exit and entrance doors and fare collection equipment.

Urban buses are of various lengths, and include articulated buses, but are

usually at least 25 feet long.

The proposed amendments to the fleet rule apply to those public transit fleets

operated by government agencies or operated by private entities under contract

to government agencies. The proposed amendments to the fleet rule only apply

to urban transit buses. The proposed amendments would not apply to buses

used in shuttle services, airport shuttle services, paratransit services, and school
24

transportation services. Buses used to provide long-distance charter service,

that are generally equipped with luggage compartments, rest rooms, and

overhead storage, are not included.

The proposed interim certification procedures for heavy-duty hybrid-electric

vehicles apply to urban transit buses as incorporated during a 3-year interim

period. All other heavy-duty hybrid-electric vehicles would follow incorporated

procedures on a case-by-case basis as approved by ARB’s Executive Officer.

B. Amendments to the Fleet Rule, 1956.2

1. PM Emission Reduction Proposal

Staff analyzed several alternatives to the current PM retrofit implementation

schedule that could achieve as close to the same reductions in diesel PM as

feasible. This section describes staff’s proposal for PM emission reductions.

The alternatives to this proposal are presented in Chapter IV.

In order to provide transit agencies with maximum flexibility in reducing PM

emissions, yet still aggressively reduce in-use PM emissions, staff proposes to

amend the rule and replace the PM retrofit program with a program that requires

that transit agencies reduce their total diesel PM emissions through 2009. The

proposed schedule is based on the implementation dates set in the original

regulation’s implementation schedule based on the fuel path selected by the

transit agency. The proposed new schedule is provided in Table 5, below.

As listed in the table, beginning in 2004 each transit agency would be required to

achieve a percent reduction of their January 1, 2002, total diesel PM emissions

baseline. For example, in 2004 transit agencies that selected the diesel fuel path

would be required to reduce their January 1, 2002, total diesel PM emissions

baseline by 40 percent. Transit agencies that selected the alternative fuel path,

however, would be required to reduce their January 1, 2002, total diesel PM

emissions baseline by 20 percent. By 2007, transit agencies on the diesel path

would be required to achieve an 85 percent emission reduction of their PM

emissions baseline. This is two years earlier than transit agencies that have

selected the alternative fuel path.
25

Table 5

Proposed Compliance Schedule for Total Diesel PM Emission

Compliance Year

(as of January 1st)

Diesel Fuel Path

Percent Reduction

Alternative Fuel

Path

Percent Reduction

2004 40 20

2005 60 40

2007 85 60

2009 85 85

The diesel PM emission reduction proposal applies only to diesel-fueled, dualfueled, bi-fueled, and diesel HEBs, in other words, any engine that uses diesel

fuel and has diesel PM emissions. A transit agency with only alternative-fueled

buses does not have to reduce its total diesel PM emissions, because

alternative-fueled buses emit zero diesel PM emissions. However, a transit

agency with mostly alternative-fueled buses and some diesel-fueled buses would

be required to reduce PM emissions from its diesel buses only. In this case a

PM emissions baseline would only be calculated for the transit agency’s diesel

buses. This proposal is designed to ensure that every diesel fleet will have its inuse PM emissions significantly reduced by 2007 or 2009, depending on fuel path.

Staff is proposing additional modifications to the rule to allow transit agencies to

apply for delays under special circumstances. In the first case, a transit agency

that cannot comply with the percentage reductions because technology is not

available may apply for an implementation delay of up to one year for each of the

compliance deadlines. The transit agency must justify its request by providing

the Executive Officer with information on why technology is unavailable, for

example, either the technology is not being sold yet or it is being sold but all units

have already been purchased by others. Additional required information includes

why the transit agency cannot comply by retiring older buses, a plan for

compliance, and when the transit agency can comply. In the case where

technology is on the market but sold out, the transit agency should supply

correspondence with the manufacturer that states when the units would be

available.

In the second case, a transit agency that operates fewer than 20 buses and is

located in a federal one hour ozone attainment area may delay complying with
26

the intermediate deadlines of January 1, 2004, 2005, and 20071 so long as the

transit agency complies with the 85 percent reduction requirement by either

January 1, 2007 (diesel path) or January 1, 2009 (alternative fuel path). In this

case, the transit agency does not need to make an application for delay, but

should include information regarding its intent in its annual reports.

Two other new sections describe how transit agencies are to reduce diesel PM

emissions through the use of aftertreatment or other add-on devices. In the first

section, staff proposes that transit agencies be required to use only diesel

emission control strategies that are verified by the ARB under

section 2700 et seq., title 13, CCR, or an urban bus retrofit kit certified and

exempted from Vehicle Code section 27156 as an engine rebuild kit. The engine

rebuild kits that are currently certified for use in California may be applied to

engines of model 6V92 TA DDEC for various specified model years and reduce

diesel PM emissions to 0.1 g/bhp-hr.

Additionally, staff provides guidance to transit agencies as to the allowable

percentage reductions when using a diesel emission control strategy. The

verification procedure categorizes a strategy into Level 1, which is a minimum of

25 percent reduction, Level 2, which is a minimum of 50 percent reduction, or

Level 3, which is a minimum of 85 percent reduction. It is these values that staff

proposes be used by transit agencies when calculating their diesel PM emission

reductions.

Finally, section 1956.2 (f)(6) (formerly 1956.2 (f)(5)), which requires that transit

agencies use only diesel fuel with a sulfur content of less than 15 parts per

million by weight as of July 1, 2002, in their diesel buses, has been modified to

allow the use of a fuel that is verified by the Executive Officer as a diesel

emission control strategy (i.e. emulsified fuels). This is necessary because a

verified fuel may be something other than a ultra low sulfur diesel fuel, and yet be

verified to reduce diesel PM emissions.

2. Fuel Path Change

Staff has analyzed the impact of allowing a transit agency to change its fuel path

three years into the implementation of what is a fifteen year rule. In establishing

the fleet rule, the implementation dates for transit agencies on each fuel path

were determined in order to ensure that emission reductions were essentially

equivalent over the life of the rule. A transit agency on the alternative fuel path

has been required to make 85 percent of its annual purchases or leases of

alternative fuel buses since the January 31, 2001, fuel path selection date.

Transit agencies that selected the diesel path have been purchasing only dieselfueled buses, which are less expensive than alternative-fueled buses. Thus, a

transit agency that changes now from the diesel path to the alternative fuel path

 

1

 The 2007 delay only applies to a transit agency on the alternative fuel path. A transit agency on

the diesel path would be required to comply in 2007 as this is the full compliance deadline.
27

would have a higher proportion of diesel buses and lower proportion of

alternative fuel buses over the life of the rule (through 2015).

As stated in the Staff Report for the regulation, the alternative fuel path was

designed to achieve equivalent NOx and greater PM reductions than the diesel

path. The rule also includes incentives for transit agencies on the alternative fuel

path in terms of timing of the PM retrofit schedule, ZEB demonstration program,

and timing of ZEB purchases (ARB 1999). An argument for not allowing transit

agencies to switch paths, some three years into the regulation, is that such a

change could affect the overall emission reductions achieved and the ZEB

program.

The transit agencies located in the SCAQMD, however, are subject to Rule 1192,

Clean On-Road Transit Buses, which was adopted June 16, 2000. The rule

specifies that all purchases or leases of heavy-duty vehicles must be alternativefueled, as of the date of adoption for transit agencies with 100 or more urban

buses and as of July 1, 2001, for transit agencies with 15 or more urban buses.

Seven transit agencies in the SCAQMD elected the diesel fuel path under the

ARB’s rule (Table 6). All but one of these transit agencies2 must follow the

SCAQMD rule where it is more stringent, i.e., they must purchase alternative fuel

buses.

Table 6

Transit Agencies in the SCAQMD on the Diesel Fuel Path

Transit Agency Size of Fleet

Commerce Municipal Bus Line312

Gardena Municipal Bus Line 35

Long Beach Transit 190

Montebello Bus Line 78

Norwalk Transit 24

Santa Clarita Transit 60

Torrance Transit 33

None of the transit agencies in the SCAQMD are mandated to participate in the

ZEB demonstration project, which only applies to transit agencies on the diesel

path with more than 200 urban buses in their fleet as of January 31, 2001. The

schedule for ZEB purchases is dependent both on fleet size and fuel path, but is

 

2

 Commerce is not subject to Rule 1192 because it has fewer than 15 buses.

3

 With only 12 urban buses in its fleet, Commerce is not subject to Rule 1192 and may purchase

diesel buses.
28

determined based on fleet size as of either January 1, 2007, for diesel path

agencies or January 1, 2009, for alternative fuel path agencies.

In order to determine which, if any, transit agencies would consider making a fuel

path change, staff notified transit agencies and asked for comment on the

proposal at workshops in Sacramento on May 3 and El Monte on May 9. Staff

then sent electronic mail (e-mail) to the California Transit Association, again

requesting comments from members, and finally sent e-mails to the transit

agencies on the diesel path in the SCAQMD. In response, staff received one

positive response (would change), one negative response (would not change),

and one response that the transit agency would consider making the switch if the

regulation was changed. The only transit agencies that responded to the request

for comment were in the SCAQMD.

Staff concludes, therefore, that there is little interest in transit agencies making a

fuel path change, and that the only transit agencies that would likely change are

located in the SCAQMD. Allowing any transit agencies in the SCAQMD to

change fuel path would have little or no impact on the benefits expected from the

current regulation. Transit agencies in the SCAQMD have already been

purchasing alternative fuel buses, because of the requirements set forth in South

Coast’s Rule 1196 pertaining to large heavy-duty fleets operating in the

SCAQMD. Staff therefore proposes to limit the scope of the fuel path change

only to transit agencies in the SCAQMD, and to require that any transit agency

that wishes to change fuel path make a declaration of its intention by

January 31, 2004. This date would allow transit agencies sufficient time to bring

the question before their management or Board, and would allow them to

combine reporting with the annual report due each January 31st.

3. Alternative Fuel Bus Purchase Provision for Diesel Path Transit

Agencies

Staff proposes to delete the language “alternative-fueled” from

section 1956.2 (d)(4) to remove the restriction on transit agencies on the diesel

path from purchasing model year 2004 to 2006 alternative-fueled urban bus

engines with NOx exhaust emission standards in excess of 0.5 bhp-hr. The

intended effect of this change is to encourage transit agencies on the both paths

to purchase alternative-fueled bus engines during this time period when staff

expects there to be no complying diesel-fueled engines available.

4. Transit Agency Request for Delay

Staff is proposing that a new section be added to the existing regulation allowing

transit agencies with fewer than 20 buses to request an implementation delay

based on financial hardship. Current regulations have significant flexibility

incorporated for the larger transit agencies (> 20 buses) to comply with the
29

requirements. For very small transit agencies, financial hardship is a valid

reason to consider in granting a delay for compliance.

The new provision is designed to provide a mechanism whereby ARB’s

Executive Officer can hear and decide on the merits of exceptional requests for

an implementation delay. The transit agency would be required to provide

evidence of financial hardship. Evidence must include an analysis of the cost of

compliance, the source of funds available for complying with the regulation, the

shortfall between funds available and the cost of compliance, and the data by

which the transit agency would achieve compliance. The Executive Officer would

then consider the transit agency’s request along with the emission reductions

forgone by delayed compliance before issuing a decision.

The new section allows a transit agency to apply for the delay within 30 days of

the implementation deadline. Until a decision is made, a transit agency would be

responsible for compliance. As the Executive Officer may take up to 90 days to

render a decision, however, the transit agency should apply earlier to avoid the

assessment of noncompliance penalties.

5. Amended Definitions

Staff proposes to modify the definition of “active fleet” to the following: “Active

fleet means the total number of urban buses operated by a transit agency or

under contract to a transit agency, including spare buses, but not emergency

contingency vehicles or non-revenue producing vehicles.”

Staff proposes to add two definitions, for “emergency contingency vehicle” and

“spare bus,” which are used in the definition of “active fleet.” The proposed

definitions are modeled on those published by the Federal Transit Administration

National Transit Database (http://www.ntdprogram.com, 2001).

“Emergency contingency vehicle” would be defined as an urban bus placed in an

inactive contingency fleet for energy or other local emergencies, after the urban

bus has reached the end of its normal minimum useful life.

“Spare bus” would be defined as an urban bus that is used to accommodate

routine maintenance and repair operations, and to replace a bus in scheduled

service that breaks down or is involved in an accident.

There should be no impact from these changes, as staff has referred transit

agencies to these already-existing definitions for “emergency contingency

vehicle” and “spare bus” when a transit agency is determining the composition of

its active fleet.
30

Staff proposes to modify the definition of “alternative fuel” as follows:

“Alternative fuel” means natural gas, propane, ethanol, methanol, electricity, fuel

cells, or advanced technologies that do not rely on diesel fuel except as a pilot

ignition source at an average ratio of less than 1 part diesel fuel to 10 parts total

fuel on an energy equivalent basis. Alternative fuel also means any of these

fuels used in combination with each other or in combination with other non-diesel

fuels. Urban bus engines operating on alternative fuel may not have the

capability to idle or operate solely on diesel fuel at any time.

The definition of alternative fuel is changed to include an engine that uses diesel

fuel only as a pilot ignition source at less than 10 percent of the total fuel usage.

The energy equivalent basis is in terms of Btus per gallon. In this case, natural

gas is the primary fuel and the use of diesel fuel is limited to the small pilot

quantity required to initiate combustion, precluding engine operation or idling

solely on diesel fuel. Because natural gas is the primary fuel, allowing this small

usage of diesel fuel in a system otherwise alternative-fueled is appropriate.

Prohibiting such an engine from operating or idling solely on diesel fuel ensures

that an engine with multiple operating modes, which may include operation on

diesel fuel, does not come under this definition.

6. Repeal California Certification Procedures for PM Retrofit Devices

Staff proposes to repeal the "California Certification Procedures for PM Retrofit

Devices for On-Road Heavy-Duty Diesel Vehicles,” adopted November 22, 2000,

that are incorporated by reference in 1956.2 (f)(7). In its place, the Board

adopted in May 2002, the "Diesel Emission Control Strategy Verification

Procedure, Warranty and In-Use Compliance Requirements for On-Road, OffRoad, and Stationary Diesel-Fueled Vehicles and Equipment," new sections

2700-2710, chapter 14, title 13, CCR. The proposed amendments require that

any device installed on urban buses to meet the diesel PM reduction requirement

be verified under the procedures adopted therein.

This change is necessary so manufacturers of all diesel emission control

strategies follow the same procedures and have the same warranty and in-use

compliance requirements for verification. As no manufacturer has followed the

certification procedures that staff proposes to repeal, this change has no impact

on transit agencies or businesses. This change will have a beneficial impact on

transit agencies because the newly adopted verification procedures provide

greater assurance of efficacy and reliability of the device.

C. HEB Interim Certification

Based on preliminary results from HEBs tested following a chassis-based

procedure, staff considers HEBs to be a viable technology for reducing emissions

from urban transit buses. Full market penetration of the hybrid-electric drive
31

systems in urban buses, and eventually heavy-duty vehicles, will continue to be a

challenge until a niche market is realized. The technology is rapidly changing

with improvements in diesel HEBs to an expanded market for gasoline, natural

gas, and fuel cell HEBs. In order for these systems to enter into the market

smoothly and provide California with substantial emission reductions, recognition

of full emission benefits is necessary. Staff proposes manufacturers to certify

buses following a chassis-based test procedure and a calculation of emission

reductions from the hybrid-electric drive system. Exhaust emissions would be

verified following the HEB test procedures briefly described in section 9, below,

(full detailed description in Appendix B). In lieu of testing, manufacturers would

also have the choice to claim a 25 percent reduction from the engine’s NOx

certification value. Manufacturers may also continue to follow existing engine

test procedures. Other types of heavy-duty hybrid-electric vehicles would also be

eligible for certification on a case-by-case basis through the approval of ARB’s

Executive Officer.

Initially, flexibility is needed so manufacturers could sustain a market in the urban

bus arena allowing the technology ample time to flourish from the urban bus into

the heavy-duty vehicle market. To facilitate the introduction of this promising

new technology in California, and to provide staff with a period of further

evaluation of the technology, staff proposes interim certification procedures for a

period of three years. To allow for additional flexibility staff proposes an

approach that allows engine manufacturers to remain responsible for emissions

from the engine during the interim period, while the hybrid-electric drive system

manufacturer would be responsible for the emission reductions it provides for the

HEB (“dual party” or “single party certification”). This approach would provide

hybrid-electric drive system and engine manufacturers a period to develop a

working relationship, collaborate efforts, and determine who would remain

responsible for emissions beyond the interim period. Recognizing the merits and

the age of the technology staff is also proposing relaxed useful life requirements

during the interim period. In addition, proposed durability and emission testing

requirements during the interim period would be based on the quantity of HEBs

sold for a particular HEB family.

1. Definitions

Staff is defining various terms related to HEBs that are equivalent to those

defined in the approved SAE J2711. These definitions are provided in

Appendix B. The interim certification procedure includes using an emissions

ratio factor to calculate a certification standard for the HEB. The ratio is

determined by comparing emissions from a baseline certified heavy-duty engine

and a baseline urban transit bus with emissions resulting from a chassis tested

HEB.

ARB’s Executive Officer would select the “baseline engine” that best represents

the engine used in a family of HEBs as part of the hybrid-electric drive system.
32

Certified emissions for the selected engine would be used in calculating an

emission factor for a particular hybrid-electric drive system. The “baseline urban

transit bus” would also be selected by the Executive Officer to represent a

conventional drivetrain (non-hybrid-electric) urban transit bus. Exhaust

emissions for the “baseline urban transit bus”, as determined by the chassis

dynamometer test procedure, would be used with the certified emissions for the

engine incorporated into that urban transit bus to calculate a non-HEB emission

factor. The ratio of the hybrid emission factor to the non-HEB emission factor will

then be used to calculate the appropriate emission reduction for a hybrid-electric

drive system.

2. Test Procedures

The procedures for determining compliance with the urban transit bus emission

standards applicable for 2004 and subsequent hybrid-electric urban buses are

based on a chassis dynamometer test procedure and calculation of emissions

attributed to the hybrid-electric drive system. The chassis dynamometer test

procedure is a modified version of a SAE Recommended Practice, SAE J2711,

developed for heavy-duty hybrid-electric vehicles. An emissions factor is

calculated from the chassis dynamometer test results and the engine certification

value for both an HEB and baseline urban transit bus. The ratio of the two

emissions factors is then applied to the engine certification value of the engine

used in the HEB, resulting in a hybrid-electric drive system certification value.

Staff proposes that the Board adopt the modified chassis dynamometer test

procedure with the emission factor ratio calculation and application as the

method for determining exhaust emissions from hybrid-electric drive systems

during the interim period.

SAE J2711, “Recommended Practice for Measuring Fuel Economy and

Emissions of Hybrid-Electric and Conventional Heavy-Duty Vehicles”, was

formally approved in April 2002, and is considered a starting point for

standardizing heavy-duty hybrid-electric vehicle testing. Staff has modified this

comprehensive document for use as a chassis dynamometer test procedure for

HEBs. SAE J2711 recommends the use of three driving cycles for exhaust

emissions testing. Staff’s proposed test procedure requires two heavy-duty

vehicle driving cycles, the Orange County Bus Cycle and the Urban

Dynamometer Driving Schedule (d) cycle, as well as the option of substituting a

different driving cycle upon approval of ARB’s Executive Officer. The SAE

procedure includes a method for correcting the state of charge (SOC) for a series

of test runs, resulting in emissions or fuel economy determination at zero net

energy change (NEC). The test procedure proposed by staff does not use a

SOC correction but instead requires each test run have a NEC variance of less

than two percent. In addition, staff’s proposed test procedure includes a

provision for chassis dynamometer testing of conventional drivetrain urban transit

buses, which is necessary for calculating the emission factor ratio.
33

Chassis level certification standards do not exist for heavy-duty vehicles and

current engine certification methods do not reflect any emission reductions

attributable to a hybrid-electric drive system. Staff proposes using an emission

factor ratio for calculating a hybrid-electric drive system certification value from

an engine certification value. An emissions factor is calculated by dividing the

chassis test procedure result by the engine certification value. Emissions factors

are calculated for both a hybrid-electric drive system and a baseline

(conventional) urban transit bus. An emission factor ratio is then determined by

dividing the emissions factor for the hybrid-electric drive system by the emissions

factor for the baseline urban transit bus. The emission factor ratio is a number

less than one and is indicative of the emission reduction benefit of the hybridelectric drive system. The engine certification value is multiplied by the emission

factor ratio to determine a certification value for the hybrid-electric drive system.

Emission factors can be calculated for any mass emission or particulate emission

species. Staff proposes to use the emission factor method for calculating NOx

certification values for hybrid-electric drive systems. An example of applying an

emission factor ratio for hybrid-electric drive system certification is provided in

Figure 3.

Figure 3: Example of Emission Factor Ratio Calculations

Hybrid-electric Bus NOx = 8 g/mi

Engine (Hybrid-electric Bus) NOx = 2.5 g/bhp-hr

EFhybrid = 8 g/mi = 3.2 bhp-hr/mi

2.5 g/bhp-hr

Baseline Bus NOx = 15 g/mi

Engine (Baseline Bus) NOx = 2.5 g/bhp-hr

EFbaseline = 15 g/mi = 6.0 bhp-hr/mi

2.5 g/bhp-hr

EFR = 3.2 bhp-hr/mi = 0.53

6.0 bhp-hr/mi

Hybrid-electric Buscert NOx = 2.5 g/bhp-hr x 0.53 = 1.3 g/bhp-hr

Where,

g/mi = grams per mile

g/bhp-hr = grams per brake horsepower-hour

EF = emissions factor

EFR = emission factor ratio

Hybrid-electric Buscert = certification value for hybrid-electric drive system
34

In the example provided above, NOx emission values for a hybrid-electric drive

system and a baseline urban transit bus were obtained by chassis dynamometer

testing. The NOx emission value for the engine used in either the hybrid-electric

drive system or baseline urban transit bus was provided by engine certification.

In this example, an emission factor ratio of 0.53 is calculated. The certification

value of 1.3 g/bhp-hr for the hybrid-electric drive system reflects a 47 percent

emission reduction attributed to the hybrid electric drive system.

If a single party assumed sole responsibility of emissions for the HEB in the

above example, the certification value on the Executive Order would be as low as

1.3 g/bhp-hr, where as the certification standard would be the optional standard

of 1.5 g/bhp-hr. If two parties (i.e. the engine manufacturer and the HEB system

manufacturer) assumed responsibility for emissions, two Executive Orders would

be granted. The engine manufacturer would be responsible for the emissions

from the engine that is incorporated into the hybrid-electric drive system,

2.5 g/bhp-hr. The Hybrid-electric Bus manufacturer would be responsible for the

hybrid-electric system that reduces emissions to the optional emission standard

of 1.5 g/bhp-hr.

3. Certification

Staff is proposing an approach for interim certification that provides

manufacturers with flexibility in introducing this viable technology into California’s

market, while still providing staff with ample time to evaluate technology for

proper enforcement. With new technology, the conventional approach would be

to allow the technology to be demonstrated through experimental permit. Under

that approach, however, once the permit expires the technology would be

removed from operation until certified. Under staff’s proposal, during the interim

period dual party or a single party certification would be granted through the

2006 model year. This approach provides manufacturers with an extended

window of opportunity to develop technology to meet the more stringent

enforcement requirements of a fully certified engine.

Under dual party certification two Executive Orders would be granted. One

Executive Order would be for the baseline engine/turbine/fuel cell that is used as

a source of motive energy (auxiliary power unit). The Executive Order for the

baseline engine/turbine/fuel cell must contain certification levels that meet

California’s most current emission standards for heavy-duty on-road or urban

transit bus engines. For PM, the engines must be certified to meet the PM

emission standards for urban bus engines. Exhaust emission standards would

be tested following “California Exhaust Emissions Standards and Test

Procedures for 1985 and subsequent Heavy-Duty Diesel Engines and Vehicles,”

or “California Exhaust Emission Standards and Test Procedures for 2004 and

Subsequent Model Year heavy Duty Otto-Cycle Engines.” Optional test

procedures for the turbine or fuel cell would be used at the approval of ARB’s

Executive Officer.
35

The second Executive Order would be for the electric drive components listing

overall emission standard for the hybrid-electric drive system. Overall emissions

would be determined by multiplying the engine certification by an emission factor

ratio determined for the hybrid electric drive components. The end result would

be a certification value in units of g/bhp-hr. The HEB must meet California’s

most current emission standards for Urban Transit Buses following “California

Interim Certification Procedures for 2004 and Subsequent Model Hybrid-Electric

Vehicles, In the Urban Bus and Heavy-Duty Vehicle Classes.”

Beginning with the 2007 model year, one party would be granted an Executive

Order. The Executive Order must contain certification levels that meet

California’s most current emission or optional emission standards for urban

transit bus engines. Exhaust emission standards would be tested following

“California Interim Certification Procedures for 2004 and Subsequent Model

Hybrid-Electric Vehicles, In the Urban Bus and Heavy-Duty Vehicle Classes.”

On a case-by-case basis, a heavy-duty hybrid-electric vehicle may be certified

with the approval of ARB’s Executive Officer.

4. 25 Percent Reduction Claim

During the interim period, hybrid-electric drive system manufacturers have the

option of claiming a 25 percent reduction from the certification standard of any

on-road certified heavy-duty engine incorporated as part of the hybrid-electric

drive system. During this period, ARB’s Executive Officer also has the authority

to chassis test any HEB that incorporates a hybrid-electric drive system selecting

this option. If the resulting emission reduction is smaller, the entire HEB family

incorporating the system in its platform would be required to claim the smaller

percent emission reduction.

After the interim period, this option is not available. Hybrid-electric drive system

manufacturers must follow the proposed “California Interim Certification

Procedures for 2004 and Subsequent Model Hybrid-Electric Vehicles, In the

Urban Bus and Heavy-Duty Vehicle Classes,” for testing and emission standards

certification.

5. Useful Life, Warranties, Testing, and Emissions Related Maintenance

In order to provide flexibility and allow HEBs to enter into the market place more

quickly, staff is proposing that for the interim period (model years 2004 through

2006) the useful life of the hybrid electric drive system would be 5 years or

150,000 miles, which ever occurs first. After the interim period the useful life

requirement would remain consistent with already adopted urban transit bus

regulations, 10 years, 435,000 miles or 22,000 hours, which ever occurs first.

The emissions defect and performance warranties would be five years,
36

100,000 miles, or 3,000 hours of operation, whichever occurs first. An alternative

useful life would be acceptable as approved by ARB’s Executive Officer.

For 2004 and subsequent model years the HEB and its engine (diesel or ottocycle), turbine, or fuel cell, and the electric drive components, by model year,

would meet the requirements as listed in title 13, CCR sections 2035 and 2036:

“Defects Warranty Requirements for 1979 through 1989 Model Passenger Cars,

Light-Duty Trucks, and Medium-Duty Vehicles; 1979 and Subsequent Model

Motorcycles and Heavy-Duty Vehicles; and Motor Vehicle Engines Used in Such

Vehicles.”

During the interim period, staff proposes durability and emission testing

requirements for an HEB family similar to what is already approved for urban

transit buses. While durability and emissions testing would remain the same,

during the interim period testing would be conducted only when a certain quantity

of HEBs are sold per HEB family. Staff proposes that HEB families with less

than 50 HEBs sold for the 2004 through 2006 model years be exempt from

durability-data vehicle and emission-data vehicle testing. An HEB family in

California with 50 or more HEBs sold, and any HEB families (regardless of the

quantity of HEBs sold) 2007 and later would meet the durability-data vehicle and

emission-data vehicle testing as required in title 13, CCR, sections 2111, 2112,

and Appendix A as adopted and last amended.

Staff proposes that emission related maintenance intervals for the HEBs

emission related components would be the same as already approved for heavyduty urban bus engines.

6. Labeling Requirements

The applicant shall label each hybrid-electric drive system with a permanent,

non-destructible label or stamp identifying the manufacturer, the model number,

the month and year of manufacture, and the Executive Order number issued by

the ARB. Labeling must conform with title 13, CCR, section 1965. Specific

details on labeling are listed in Appendix B, “California Test Procedures for 2004

and Subsequent Model Hybrid-Electric Vehicles, in the Urban Bus and Heavyduty Vehicle Classes.” The label or stamp shall be easily visible after installation

of the system according to the applicant’s written instructions for proper

maintenance and use. Each applicant shall submit a sample of its label or stamp

to the ARB for review and approval, prior to selling the hybrid-electric drive

system. Staff will propose modifications to the current labeling requirements for

all heavy-duty vehicles in a regulatory item next month. Those modifications may

also apply to HEBs.
37

7. Engine Service Manuals

Staff proposes that the Board adopt the same manufacturer requirements for

service manuals as already approved for urban transit buses. The

manufacturers of HEBs would provide owners with manuals specifying

maintenance needed to ensure proper hybrid-electric drive system operation.

The manual would also identify maintenance that may be needed for emissionsrelated components after the end of the regulatory useful life of any components,

including mileage/hour intervals, and procedures for determining whether

maintenance or repair is needed. Manufacturers are not required to incorporate

additional on-board systems beyond what they already have. However, the

maintenance manual must include instructions for access and responding to any

emissions-related diagnostic codes that may be stored in any existing on-board

monitoring systems.

The recommended maintenance practices may be based on engineering

analysis or other sound technical rationale. In the event that an emission-related

component is designed not to need maintenance during the full life of the engine

or electric drive system, the manual would need to contain, at a minimum, a

description of the component, noting its purpose, and a statement that the

component is expected to last the life of the engine and electric drive system

without maintenance or repair. In addition, the manual would include the rebuild

provisions described in item 9 below, to ensure that owners and rebuilders are

aware of the requirements.

8. Equipment Maintenance Signals

According to Health and Safety Code section 43009 manufacturers must ensure

that critical emissions-related scheduled maintenance has a reasonable

likelihood of being performed in-use. Manufacturers may chose a form of onboard driver notification that would be triggered based either on mileage intervals

or component failure. Staff proposes that regulatory requirements already

approved for equipment maintenance signals used in heavy-duty vehicles also

be set for HEBs. Specifically, manufacturers of 2004 and subsequent modelyear hybrid-electric drive systems must use equipment maintenance signals

designed to function at or beyond the end of the regulatory useful life of the HEB.

Recall liability is limited to failures during the regulatory useful life.

9. Rebuild Provisions and Record Keeping Requirements

Section 27156 of the California Vehicle code prohibits tampering, when

rebuilding engines or at any other times. Currently, for 2004 and subsequent

model-year heavy-duty diesel and Otto-cycle engines no one may remove or

render inoperative any device or element of design installed on or in a heavyduty vehicle or engine in compliance with current regulations. Furthermore, a
38

remanufactured engine must be rebuilt equivalently from an emissions

standpoint, to the original certified engines. Staff proposes the Board adopt

rebuild requirements for HEBs and hybrid-electric drive systems incorporated into

HEBs. The proposed rebuild requirements would be the same as those already

approved for heavy-duty vehicles and engines and would apply to the hybridelectric drive system at the time of rebuild.

Staff also proposes that the Board adopt record keeping requirements for HEB

rebuilds that are consistent with those already adopted for heavy-duty vehicles

and engines. These requirements include the following

• Mileage and/or hours at the time of hybrid-electric drive system rebuild;

• A list of the work performed on the hybrid-electric drive system

(engine/turbine/fuel cell and electric drive components);

• Any repair of emission control systems, including a list of replacement

parts used, hybrid-electric drive system parameter adjustments, and

design element changers;

• Emissions-related codes and equipment monitoring signals that are

responded to and reset; and

• Responses to such signals and codes, and work performed.

Staff proposes records be kept for two years after the hybrid-electric drive system

is rebuilt. For single party responsibility, maintaining records for HEB families

rather than specific engines is allowed. However, under dual party responsibility,

records would be maintained for the engine/turbine/fuel cell family separate from

those for the electric drive components.

10. Information Requirements

When applying for certification, the application except as noted below, must

follow Part I (40 CFR §86.1843-01(c)):

• Identification and description of the vehicle(s) covered by the application.

• Identification of the heavy-duty vehicle weight category to which the

vehicle is certifying: light heavy-duty, medium heavy-duty, heavy-heavy

duty, urban transit bus, and the curb weight and gross vehicle weight

rating of the vehicle.

• Identification and description of the propulsion system for the vehicle.

• Identification and description of the climate control system used on the

vehicle.

• Projected number of vehicles produced and delivered for sale in

California, and projected California sales.
39

• All information necessary for proper and safe operation of the vehicle,

including information on the safe handling of the battery system,

emergency procedures to follow in the event of battery leakage or other

malfunctions that may affect the safety of the vehicle operator or

laboratory personnel.

• Method for determining battery state-of-charge, and any other relevant

information as determined by the Executive Officer.
40

IV. TECHNOLOGICAL FEASIBILITY

There have been major advances in heavy-duty diesel engine technology over

the last several years to meet current and future PM and NOx standards for

heavy-duty and urban bus engines. Retrofit manufacturers continue to improve

PM retrofit technology that could be used in urban transit buses to meet future

PM standards. Part of the challenge in meeting current PM requirements for

urban buses will be having retrofit technology available for older buses.

Hybrid-electric drive system manufacturers have developed innovative

technology to provide urban transit agencies with another method for meeting the

current and future standards. Although considered a viable solution, entering

into the production stage in California is a challenge for HEB manufacturers.

Staff’s proposal for PM retrofits and hybrid-electric buses was designed

considering the progress of PM retrofits and the fairly young and rapid

development of hybrid-electric drive technology. This chapter discusses the

feasibility of staff’s proposal for PM retrofits and HEB certification.

A. PM Emission Reduction Technology

Transit agencies may use a variety of methods to reduce their diesel PM

emissions to comply with the proposed diesel PM emission reduction

requirement, including bus retirement, engine repower, purchase of new lowemission buses, and installation of a verified diesel emission control strategy.

Transit agencies may retire older buses or repower engines certified to higher

emissions levels and replace them with newer diesel, dual-fuel, bi-fuel, or diesel

hybrid-electric buses certified to 0.01 g/bhp-hr, or with alternative fuel buses.

Replacement of a diesel bus with an alternative fuel bus also reduces the total

diesel PM emissions.

A transit agency may comply with this proposal by installing a diesel emission

control strategy that has been verified by ARB’s Executive Officer to reduce

diesel PM. There are several different options verified at Level 3, which is a

verified 85 percent or greater reduction, and one option verified at Level 1, which

is a verified 25 percent or greater reduction. Staff expects that additional

technologies at all Levels will be verified for urban bus engines as a result of this

proposal. Removal of the requirement to use only 85 percent reduction

technologies will open the market to more innovative technologies for urban

buses. Thus, a transit agency can use a variety of technologies and strategies to

comply with this proposal.
41

Staff has reviewed retrofit technology for diesel PM reduction in the

September 2001 and March 2002 status reports for the transit bus fleet rule

(ARB 2001, ARB 2002). Staff’s review of these technologies is provided in

Appendix D. Other possible strategies that have been discussed with staff

include alternative diesel fuels, such as a fuel-water emulsion; fuel additives,

used with or without a diesel particulate filter; a fuel delivery optimization

mechanism; a diesel oxidation catalyst used alone or in combination with a diesel

fuel-water emulsion; cam modifications; and catalytic coatings inside the cylinder.

Some of these strategies are newly developed, while others have been in use for

years, especially in Europe or in other industries such as mining. Verification by

ARB proves to the consumer and to the State that the diesel emission control

strategy is effective and durable, and provides a standard warranty that provides

the user with some protection. Thus, any technology that has been verified is

both feasible and effective.

B. Availability of Ultra Low Sulfur Diesel Fuel

Beginning July 1, 2002, public transit agencies were required to operate their

diesel buses on diesel fuel with a sulfur content of 15 parts per million by weight.

To ensure availability of ultra low sulfur diesel fuel, staff surveyed each transit

agency to determine availability in and around their area for heavy-duty buses in

their fleets. Eight of the transit agencies operate fleets of only alternative fuel

urban buses and, therefore, were excluded from the survey.

The regulation allows a transit agency that has fewer than 20 buses and

operates in a one-hour ozone attainment area to delay implementation of the

ultra low sulfur fuel requirement to July 1, 2006. Nine transit agencies are

located in a one-hour ozone attainment area and have fewer than 20 buses

(Table 7), and can therefore delay implementation of the requirement. Of these

nine, two transit agencies – Monterey-Salinas Transit and Santa Cruz

Metropolitan Transit – began using the fuel by July 1, 2002:
42

Table 7

Transit Agencies Eligible for Fuel Delay

Transit Agency Implement

by 07/01/02

Delay to

07/01/06

Arcata & Mad River Transit X

Eureka Transit Service X

Humboldt Transit Authority X

Mendocino Transit Authority X

Monterey - Salinas Transit X

Redding Area Bus Authority X

San Luis Obispo X

San Luis Obispo Regional

Transit Authority

X

Santa Cruz Metropolitan

Transit District

X

Siskiyou County STAGE X

South County Area Transit X

The majority of the remaining 50 transit agencies have the fuel readily available

to them with a cost differential ranging from $0.05 to $0.12 per gallon relative to

regular diesel fuel. Approximately 62 percent of these transit agencies contract

to purchase the ultra low sulfur diesel fuel and the remaining 38 percent

purchase fuel weekly on the open commercial market.

Four transit agencies with fewer than 20 buses, but that operate in one-hour

ozone non-attainment areas have requested relief from the rule because of cost

impacts: Stanislaus Regional Transit in San Joaquin Valley Unified (4 buses),

Santa Maria Area Transit in Santa Barbara County (7 buses), El Dorado County

Transit Authority in the El Dorado County (12 buses), and Chico Transit in Butte

County (10 buses). All of these very small transit agencies have discussed with

staff their claims of financial hardship because they would have to install

infrastructure (storage tanks) that would be used for only four years, or in the

case of Stanislaus, only two years. Two of the transit agencies are in air districts

that either have not been formally designated attainment (Butte) or have been

redesignated (Santa Barbara). In each case, the transit agency is claiming that

the local commercial facilities are unwilling to carry the ultra low sulfur diesel fuel

because there is not enough demand in advance of the national standard

deadline of July 1, 2006. In the absence of any delay in the rule, staff is unable

to evaluate the claims of financial hardship by transit agencies.
43

Thus, although ultra low sulfur diesel fuel is available in most areas of the state,

the high cost of installing infrastructure to bring in a fuel prior to its mandated

availability throughout the nation may render this requirement financially

infeasible for a small number of transit agencies. Section 1956.2 (g) is proposed

for addition to the regulation to allow the Executive Officer to consider

applications for delay based on financial hardship, which would allow staff to

evaluate the claims by these transit agencies. Allowing these transit agencies to

delay adopting ultra low sulfur fuel should have little or no effect on their ability to

reduce diesel PM emissions as these transit agencies could meet the

requirements by retiring buses or installing diesel emission reduction technology

that does not require ultra low sulfur fuel. In addition, staff expects the availability

of ultra low sulfur fuel to grow throughout the state. Already, ARCO stations that

carry diesel fuel now carry ultra low sulfur diesel.

C. HEBs and Interim Certification

Bus manufacturers and transit agencies have expressed interest in diesel hybridelectric technology because of their familiarity with diesel technology and its

compatibility with current fueling infrastructure. Diesel hybrid-electric technology

utilizes electric traction drive motors, batteries, and a diesel engine/generator set

combination, rather than the conventional engine/transmission combination. The

batteries, typically lead acid (PbA) or nickel metal hydride (NiMH), can be

charged by the engine/generator set and through regenerative braking. On site

“plug-in” charging may also be used to recharge batteries in some cases.

HEBs have been developed within the last decade and have been

commercialized in the last 5 years. Over this period, hybrid-electric drive

systems for urban transit buses most commonly included series or parallel

platforms. Hybrid-electric drive systems are designed in many different

configurations, incorporating compressed natural gas, liquid natural gas,

gasoline, or propane engines, as well as turbines and fuel cells into the overall

HEB platform. HEB platforms are designed so that the system achieves

maximum fuel economy and emission benefits. This is done by typically

incorporating smaller, medium-heavy duty engines (Cummins ISB 5.9 liter,

Detroit Diesel Series 30, etc.) into the hybrid-electric drive system assisted by the

power generated from the batteries. In general a HEB can achieve top speed,

range, and acceleration equal to or better than a conventional diesel bus.

Several demonstration projects with hybrid-electric buses are underway with

promising results. Preliminary reports indicate that the higher efficiencies

associated with hybrid-electric technology, compared to conventional diesel

technology, can reduce fuel consumption by 25 percent, and reduce emissions of

NOx by about 50 percent. In addition, an engine operating in a hybrid-electric

vehicle generally operates in a limited operating range. Therefore, without the

severe transient parameters that typically accompany urban bus operation,
44

exhaust aftertreatment could be designed far more efficiently. Significant

emphasis is being placed on cost reductions for future hybrid-electric buses.

Hybrid-electric drive systems are rapidly changing to improve energy

management -- storage, regeneration and fuel economy, which will translate to

greater emission reductions. Part of the challenge in developing a certification

procedure is designing a method that quantifies full emission benefits of the

technology that are comparable with the various HEB platforms and are fully

enforceable, while considering rapid modifications and improvements in the

technology. Currently, manufacturers have one option for certifying an HEB –

apply for certification to ARB on a case-by-case basis. Current procedures are

engine-based and an HEB would be certified at a level that does not represent

actual emission benefits of the HEB. Although recent ARB tests of HEBs being

demonstrated in California indicate substantial emission reductions, these

conclusions have been based on a few results and do not include all types of

HEB platforms available for commercialization. Hence, staff believes it is

appropriate to propose an interim certification procedure for three years. This

would allow ARB to work closely with manufacturers to determine whether

modifications or more appropriate requirements are warranted.
45

V. ISSUES

Staff held three public workshops to discuss proposals for amending the Public

Transit Bus Fleet Rule and one workshop with two stakeholders meetings to

discuss the proposed interim certification procedures for HEBs. This chapter

describes the issues that remain after consideration of public comments.

A. Buses that Should be Included in the Total Diesel PM Emissions

Calculation

The original regulation included a provision that exempted transit agencies from

retrofitting buses within one year (alternative fuel path) or two years (diesel path)

of retirement. This provision has been removed from the proposed amendments,

because the total diesel PM emission reduction approach allows maximum

flexibility in choosing how to comply. Some transit agencies have argued that

buses within one year of retirement should not be included in the calculations of

diesel PM. In addition, some transit agencies have argued that new buses, on

order but not yet in operation, should be figured in the diesel PM calculation,

instead of the old buses those will replace. Finally, others have argued that PM

emissions from alternative fuel buses should be included in the calculations.

Staff has considered these requests and does not feel that they are necessary or

wise. Allowing a transit agency to remove certain buses from its calculations of

total diesel PM emissions, based on an anticipated bus retirement date, would be

contrary to the goal of reducing diesel PM emissions from each transit agency’s

fleet, as the transit agency would be able to continue to operate certain buses,

without counting them in its total diesel PM emissions, for up to one year. In

addition, allowing a transit agency to include a bus that has not yet been

received, but not count a bus that is being operated in anticipation that it will be

replaced, would not make sense. Bus delivery schedules change, and thus a

bus anticipated to be delivered by one date may not arrive for several months,

and may not be fully operational for several more months.

Finally, alternative fuel buses do not emit diesel PM, thus it is not appropriate to

include their PM emissions in the calculation of diesel PM emissions. Staff has

considered including alternative fuel buses in the calculation of total diesel PM

emissions with “zero” diesel PM emissions, to provide an additional incentive to

transit agencies to purchase alternative fuel buses. This approach, however,

could encourage transit agencies with alternative fuel buses to keep the oldest,

highest emitting diesel buses in their fleets because those emissions would be

offset by the “zero” emissions from alternative fuel buses. A regulation that

allows transit agencies to offset high-emitting diesel buses with alternative fuel
46

buses would have the negative effect of allowing people who ride on those diesel

buses to continue to be exposed to the health impacts of breathing higher levels

of diesel PM. Staff is already providing a different implementation schedule for

transit agencies on the alternative fuel path, thus retaining the incentive to those

agencies provided in the original rule.

B. Baseline Emission Year that Should be Used

Staff proposed that the baseline year, against which reductions are measured, be

January 1, 2002. Staff chose this year because it was prior to the mandated

retrofit date of January 1, 2003, for all Tier 1 and some Tier 2 buses. Staff

requested comments from transit agencies if another year, such as

January 1, 2001, would be better for calculating a baseline. Staff specifically

requested that transit agencies “do the calculations” and tell us if one date would

be more advantageous than another for their agency.

Staff received two comments that an earlier year, before January 1, 2002, might

be a better date for determining a total PM emissions baseline for transit

agencies. However, no analysis was provided to ARB to back up this assertion.

Furthermore, no specific examples of any transit agency for which a different

baseline year might be better were provided. Out of the eight comment letters

received, no transit agency provided evidence that a more appropriate date was

better for its agency or any other transit agency.

Staff, however, did analyze the impact of a baseline date of January 1, 2001, on

the emissions benefits. Based on the analysis conducted, staff determined that

there would be a small negative impact on the ultimate diesel PM reductions if

we use this date as a baseline instead of January 1, 2002. Staff, therefore,

concluded that the January 1, 2002, baseline date for total PM emissions is the

most appropriate date, was acceptable to transit agencies, and provides a small

additional benefit over the January 1, 2001 baseline.

C. Request for Allowing Credit for Buses Rebuilt/Retrofitted Using a

Certified Kit Under the U.S. EPA Mandated Program

In a related comment, some transit agencies requested that ARB allow credit for

bus engines that have had their PM reduced through installation of a

rebuild/retrofit kit, perhaps by removing these buses from the total diesel PM

calculation. These kits were mandated by the U. S. EPA urban bus

retrofit/rebuild program, which in California applies to 19904 and earlier model-

 

4

 The U.S. EPA requires retrofit kits for 1994 and earlier model year urban bus engines whose

engines are rebuilt or replaced after January 1, 1995.
47

year urban bus engines. In California urban bus engines are required to meet a

0.10 g/hb-hr standard in 1991, two years earlier than the federally-adopted

0.10 g/bhp-hr standard went into effect. Many transit agencies have already

complied with this program by installing retrofit/rebuild kits on their bus engines.

The original regulation included a provision that such a bus, which had its PM

emissions reduced to 0.10 g/bhp-hr from 0.60 g/bhp-hr, did not need to be further

retrofitted.

Staff does not believe it is wise to allow what would be retroactive credit for these

buses for several reasons. First, the U. S. EPA rule applies in California to 1993

and earlier model-year bus engines. Over the life of this program, from 2004

through 2009, these buses will reach the end of their useful lifetimes and should

be removed from transit bus fleets or the engines should be repowered. The

second reason pertains to which baseline year and buses should be included in

the calculations. Since the goal is to reduce diesel PM from transit bus fleets,

staff believes that these buses should remain in the calculation of diesel PM

emissions. Furthermore, if necessary to achieve the overall program goals,

transit agencies may have to retire the buses or repower the engines to reduce

the overall total diesel PM emissions from their fleets.

D. Allow All Transit Agencies the Option of Switching to the Alternative

Fuel Path

Several comments requested that all transit agencies be given the option of

changing fuel paths. The option should remain the same as currently required.

Staff has examined all available options (including the option in the proposed

amendments), and concluded that providing only the SCAQMD with the option of

changing from the diesel fuel path to the alternative fuel path would have the

least negative impact on the anticipated benefits of the current regulation.

The current regulation has a schedule that requires the purchase and

demonstration of ZEBs in transit fleets depending on the fuel path selected.

Allowing all transit agencies the option of changing to the alternative fuel path

could have the negative effect of slowing the ZEB demonstration by reducing the

number of transit agencies required to participate and delaying purchase

requirements. Providing the six transit agencies in the SCQMD the option to

switch to the alternative fuel path would have no effect on the ZEB demonstration

and purchase provisions, with little effect on the reduction of diesel PM

emissions.

Furthermore, transit agencies in the SCAQMD requested that they be allowed to

change their fuel path because of the timing of adoption of SCAQMD Rule 1192

and ARB’s Public Transit Bus Fleet Rule. Rule 1192 was adopted

June 16, 2000, six months before transit agencies had to choose their fuel path

under ARB’s Public Transit Bus Fleet Rule. Thus, some of those transit agencies
48

believe there was insufficient time to consider the dual impacts of Rule 1192 and

ARB’s rule. In addition, the six SCAQMD transit agencies that chose the diesel

path and are subject to Rule 1192 have been required to purchase alternative

fuel buses – Long Beach Transit since June 16, 2000, and the other five transit

agencies since July 1, 2001. Thus, these transit agencies are already making

current and future purchase decisions in line with the alternative fuel path

requirements.

E. Proposed Useful Life, Durability, and Emissions Warranty Are Too

Stringent to Allow the HEB Technology Into the Market Place

The conventional approach for certification would be to require manufacturers to

certify with full useful life, durability and emission warranty requirements. Staff

worked closely with manufacturers and determined that a different approach was

necessary in order to introduce this viable technology into California’s market.

Staff understands that reliability is critical to transit agencies and that market

flexibility is critical to manufacturers. As such, staff’s proposal is designed to

provide manufacturers with flexibility, while providing urban transit agencies with

reliability. In the first 3 years (the interim period), staff’s proposal allows

manufacturers to meet a shorter useful life (when compared to conventional

useful life requirements for an urban bus): 150,000 miles or 5 years.

Recognizing that HEBs are new, limited in quantity, and have not been in

operation long enough to determine durability, staff’s proposal allows

manufacturers with less than 50 HEBs sold in California during the interim period

to be exempt from durability requirements. After the interim period,

manufacturers are expected to meet the full certification requirements already

adopted for urban bus engines.

F. HEBs Should Be Verified Following Retrofit Procedures

One manufacturer requested that ARB allow HEBs to be certified following the

Regulation for the Verification Procedure for In-Use Strategies to Control

Emissions from Diesel Engines approved by the Board May 16, 2002. The,

verification procedures were designed with the intent to certify both PM and NOx

retrofit devices. While the hybrid-electric drive system may be both a PM and a

NOx reduction device, issues associated with hybrid systems can be significantly

different than those related with aftermarket retrofits, such as DPFs. The current

verification procedures may not be the appropriate avenue for verifying

emissions from HEBs. Staff, is willing to work with manufacturers to determine a

more appropriate method, outside of this proposal and within the context of

another protocol.
49

G. Chassis Testing May Be too Costly for Measuring Exhaust Emission

Standards from HEBs

Since typically, heavy-duty and urban bus engines are certified following an

engine dynamometer test procedure resulting in engine-based standards

(measured in g/bhp-hr), and have not been correlated to chassis dynamometer

tests, some manufacturers believe that it may be too costly to follow chassisbased test procedures. Although chassis test results have not been correlated to

engine-based test standards, HEBs incorporate a technology by which actual

emission benefits could not be measured following engine-based procedures.

Several options are available to manufacturers, however. Currently,

manufacturers have the option of certifying HEBs following already adopted

engine-based procedure, as long as the engine is certified to meet the urban

transit bus regulations. Furthermore, a technology that may not fall in the

category of an engine, i.e. a fuel cell or a turbine, may also certify to the urban

bus standards on a case-by-case basis, as approved by ARB’s Executive Officer.

While less costly, testing the engine used in an HEB solely following an enginebased test procedure would result in values that may not account for full

emission benefits provided by the hybrid-electric drive system. An engine

certification may not account for the power provided by the electric drive

components, which offsets some of the load on the engine, thus reducing

emissions. Recognizing the emission reduction potential of hybrid-electric drive

system technology, ARB has provided manufacturers with the option of claiming

a 25 percent emission reduction from the engine certification standard for a

certified engine used in the HEB. To provide manufacturers with additional

flexibility, staff has proposed to extend the 25 percent reduction claim through the

interim period (3 years). This would relieve some of the costs associated with

conducting a chassis-based test during the interim.

It has been a challenge to design a chassis-based test procedure that could be

correlated to engine-based certification standards, considering the costs. Staff

worked closely with manufacturers to develop a protocol that would balance

economics, yet best represent actual benefits of the technology. One

manufacturer recommended the use of an emission factor ratio in conjunction

with the engine certification and chassis test results as a method for determining

actual emissions. Recognizing the lack of data available to correlate chassisbased emission results with engine-based emission standards for HEBs, and the

rapid change in technology, staff’s proposal incorporates the manufacturer’s

recommendation with the goal of achieving enough data to develop a correlation.

These data are necessary for staff to make a determination on the

appropriateness of the certification procedure and the need for future

modifications. It is important to recognize that this proposal is considered

voluntary, since manufacturers currently have other options available to certify

the technology on a case-by-case basis.
50

VI. REGULATORY ALTERNATIVES

A. Change PM Retrofit Schedule

Staff initially considered modifying the existing PM retrofit schedule to match its

best predictions on when technology would be available for the older, pre-1994,

engines. At this time, no PM retrofit device that reduces diesel PM by 85 percent

or more is available and verified for engines older than 1994 or for any two-stroke

engines. In addition, no technology is verified at any level, although that may

change, for engines older than 1994. Staff rejected this alternative because it

does not address the problem of reducing emissions from the oldest, dirtiest

engines, and it relies completely on retrofit technology. This alternative would

not be as effective, therefore, as the proposal.

B. Declining PM Fleet Average

Staff also considered and rejected a declining PM fleet average based on setting

a PM fleet average that every transit agency must meet or a percentage

reduction from baseline. This alternative was rejected because neither approach

obtained as much reductions in diesel PM as the preferred alternative.

For example, setting the first maximum fleet average of 0.2 g/bhp-hr to be met in

2004 would require only 10 transit agencies to reduce their PM fleet average,

some of which currently have a PM fleet average of 0.6 g/bhp-hr or more. Since

those fleets with a fleet average of 0.6 g/bhp-hr or more are made up of the

oldest engines, the only option available to the transit agency would be purchase

of new engines or complete buses. Thus, the ten dirtiest transit agencies would

have to reduce their diesel PM but no other transit agency would have to take

any action, and the cost of reducing emissions, using the methods open to those

transit agencies, would be very high.

Setting a maximum fleet average of 0.1 g/bhp-hr to be met, for example in 2006

(with a declining PM fleet average over time), would require an additional 13

transit agencies to take action. Again, the options open to these transit agencies

would be limited to replacement of the oldest engines with new engines, a very

costly proposal.

Thus, the effect of this type of a declining PM fleet average is that a transit

agency that already has relatively low average PM emissions would not have to

take any action for several years. Following the same schedule, the next cutpoint would be set at 0.05 g/bhp-hr, which would require 24 transit agencies to

reduce emissions. Within this group, large numbers of engines can be retrofitted
51

with verified diesel particulate filters, allowing these transit agencies to utilize

verified diesel emission control technologies.

Another approach, the declining PM fleet average based on percentage

reductions, was rejected because some transit agencies would be unable to

comply with the intermediate compliance deadlines. These transit agencies

made the decision to purchase alternative fuel buses some years ago but

maintain a small number (relative to the size of the fleet) of older diesel buses.

Because most or all of these buses are in the same age class, the diesel PM

fleet average does not change until all of the buses are gone from the fleet.

Therefore, to meet even the first requirement would mean the transit agency

would have to retire and replace every one of these buses. This approach is

therefore infeasible.

In conclusion, staff did not select this approach because it would be very costly

for many transit agencies. It would also allow most transit agencies to delay

action for many years, placing the burden of reducing emissions mainly on the

smaller transit agencies with the oldest engines. Finally, communities and

individuals would be impacted unequally.

C. Interim Certification for HEBs Following Chassis Test Procedure

Without Emission Factor Ratio

Staff considered allowing interim certification for HEBs following a chassis-based

test procedure, without using the proposed emission factor ratio. Following this

approach would yield test results in grams/mile. Currently emission standards for

urban transit buses are engine-based standards and measured in units of

g/bhp-hr. With emission standards changing and technology evolving rapidly,

insufficient data is available that accurately correlates engine-based standards

with chassis-based test results.

To provide leniency, staff has provided manufacturers with an option of claiming

a 25 percent reduction in lieu of testing during a 3-year interim period. In order to

allow manufacturers to claim a larger emission reduction, however, ARB must

validate emissions to ensure emission benefits are real and enforceable. Hence,

staff selected an approach that incorporates an emission factor ratio. The

emission factor ratio is designed to use both an engine dynamometer test and a

chassis dynamometer test. The engine factor ratio correlates the overall chassis

dynamometer results to certification levels in units of g/bhp-hr (engine

certification result). Staff believes that the proposed interim certification

procedure would provide data to correlate both types of emissions tests.

Furthermore, in the interim the procedure would allow staff to gather more data to

determine whether the correlation is appropriate or modification is necessary.
52

D. Continue Allowing 25 Percent Emission Reduction Claim Without

Interim Certification

Staff also considered allowing manufacturers to claim the 25 percent reduction,

as granted by the Executive Officer, instead of interim certification. While this

approach would cost less, and seems simple compared with staff’s proposal, it

would not account for the true benefit of the HEB. Preliminary test data indicates

that many HEBs could reduce NOx emissions from diesel engines by about

50 percent.

Secondly, HEBs typically incorporate medium-duty diesel engines as part of the

hybrid-electric drive system. These engines are not certified to the urban transit

bus standard. Allowing a 25 percent emission reduction would not be enough for

HEBs to meet future more stringent standards. Although a 25 percent emission

reduction claim in the interim may be sufficient to encourage sale of HEBs, in the

long term enforceability would be a challenge. Solely allowing a percent

emission reduction claim does not include durability, useful life, in-use testing,

and warranty requirements as those typically written into an interim certification

procedure.
53

VII. ECONOMIC IMPACTS

The proposed amendments to the Public Transit Fleet Rule and Emission

Standards For New Urban Buses regulation will provide transit agencies with

greater flexibility to comply with the required emission standards. Staff believes

that the proposed amendments would cause no noticeable adverse impacts in

California employment, business status, competitiveness or increase costs above

those estimated for the Public Transit Bus Fleet Rule and Emission Standards for

Urban Buses regulations adopted February 2000.

A. Legal Requirement

Sections 11346.3 and 11346.54 of the Government Code requires state agencies

proposing to adopt or amend any administrative regulation to assess the

potential for adverse economic impact on California business enterprises and

individuals. The assessment shall include consideration of the impact of the

proposed regulatory amendments on California jobs; business expansion,

elimination, or creation; and, the ability of California businesses to compete in

other states.

State agencies are also required to estimate the cost or savings to any state or

local agency and school district in accordance with instructions adopted by the

Department of Finance. This estimate is to include nondiscretionary costs or

savings to local agencies and the costs or savings in federal funding to the state.

B. Affected Businesses

Businesses that may be affected as a results of the proposed regulatory

amendments include manufacturers of heavy-duty diesel or alternative fuel bus

engines, urban buses, hybrid-electric buses, micro turbines, fuel cells, electric

drives, engine retrofit kits, and exhaust aftertreatment devices. Most

manufacturers of urban bus engines, hybrid-electric urban transit buses, and

aftertreatment devices are located outside of California. There are only three

hybrid-electric bus manufacturers and one urban bus manufacturer located in

California.

C. Potential Impact on Businesses

The proposed amendments include a modification to allow some transit agencies

to change from the “diesel” path to the “alternative fuel” path, establish a new PM
54

emission reduction requirement, and include an interim certification procedure for

hybrid-electric urban transit buses. Since the proposed amendments provide

transit agencies with greater flexibility to comply with the required emission

standards they are not expected to impose costs above those already estimated

for the Public Transit Bus Fleet Rule and Emission Standards for Urban Buses

regulations approved February 2000. The proposed amendments could provide

cost savings in some cases. (The February 2000 estimated cost per bus ranged

from $3,000 to $10,000.) Most impacts to business, both positive and negative,

will likely occur in other states.

Testing of hybrid-electric buses could increase the cost of purchasing a hybridelectric bus. Manufacturer costs for testing a family of hybrid-electric buses,

according to the proposed interim procedure, would range from $70,000 to

$120,000 per certification. However, the proposed interim certification procedure

would provide manufacturers with a method for demonstrating the full emission

benefits achieved by using a hybrid-electric drive system. Manufacturers could

opt to certify their hybrid system using current engine-based certification

procedures, depending on approval on a case-by-case basis by ARB’s Executive

Officer.

Since it is not certain how many hybrid-electric buses will be purchased the

proportional increased cost of a hybrid bus cannot be determined. A transit

agency does not typically cover the total cost of purchasing a new bus. Federal

funds are available to cover 80 percent of the total cost of a new diesel urban bus

and 83 percent of a new low emission alternative fuel bus. The remaining cost

would have to be covered by other funding sources such as state or local

incentive programs, transportation planning agencies, transit agencies, and air

quality and energy funds. Since transit agencies can make the choice among

emission control options, based on their individual transportation planning and

operational needs, the increased cost of purchasing a hybrid bus is not

considered a significant cost impact.

D. Potential Impact on Business Competitiveness

The proposed amendments are not expected to impact the ability of California

businesses to compete with businesses in other states. As indicated above,

most businesses that produce products needed to meet the proposed

amendments are located in other states. By providing additional options to

transit agencies, this proposal may actually provide new opportunities for

California business engaged in manufacturing HEBs, hybrid-electric drive

systems and respective components, and exhaust aftertreatment devices.
55

E. Potential Impact on Employment

Manufacturers of HEBs, hybrid-electric drive systems and respective

components, and exhaust after treatment devices located in California may

increase their production and thus result in the creation of new jobs.

F. Potential Impact on Business Creation, Elimination, or Expansion

The proposed amendments could impact any companies involved in the

manufacture and production of heavy-duty alternative fuel urban bus engines,

urban buses, HEBs, fuel cells, micro turbines, hybrid-electric drive systems and

respective components, and exhaust aftertreatment devices that sell in

California. Most manufacturers that could benefit from the potential increase in

business created by requiring cleaner engines and buses are located outside of

California. There are only three HEB manufacturers and one urban bus

manufacturer located in California. To the extent that those business choose to

locate in California, or in state business increase production, the amendments

could lead to the creation or expansion of businesses in California.

G. Potential Cost to Local and State Agencies

The proposed amendments are not expected to impose additional fiscal impacts

on transportation planning agencies, commissions, transit agencies, or the ARB,

above those estimated for the implementation or enforcement of the February

2000, Public Transit Bus Fleet Rule and Emission Standards for Urban Buses

regulations.
56

VIII. ENVIRONMENTAL IMPACTS, ENVIRONMENTAL JUSTICE, AND

COST-EFFECTIVENESS

This chapter presents the air quality benefits and cost-effectiveness resulting

from the implementation of the proposed amendments to the Public Transit Bus

Fleet Rule and the interim-certification procedures – “California Exhaust

Emission Standards and Test Procedures for 2004 and Subsequent Model

Hybrid-Electric Vehicles, in the Urban Bus and Heavy-duty Vehicle Classes.”

Adoption of the proposed amendments would continue to provide PM emission

reductions close to those anticipated in the original rule, while providing

additional flexibility in meeting the requirements. There are no direct air quality

benefits resulting from approval of the proposed interim-certification procedure

for HEBs. Instead there is a benefit to transit agencies that another control

option would be available to comply or potentially go beyond the already

approved urban transit bus standards.

A. Air Quality Benefits

1. PM Emission Reduction Proposal

The proposed modifications provide close to the same air quality benefits as

anticipated in the original regulation adopted in February 2000. The

amendments will reduce the public’s exposure to toxic diesel particulate

emissions and benefit California’s environment. Since February 2000, staff has

gained more information about California’s transit bus fleet, and ARB’s mobile

source inventory and modeling capabilities have been further refined. The air

quality benefits presented here have been modeled based on the January 31,

2001 and 2002 reports from transit agencies regarding composition of their fleets

and the updated mobile source inventory, EMFAC 2001, which has been

adopted by the Board.

The original transit bus rule was written to achieve maximum PM and NOx

emissions benefits with available technology, while minimizing the economic

impact on affected businesses and transit agencies. The proposed amendments

were written to maintain that same goal. Each transit agency has the flexibility

under the proposed amendments to reduce their total diesel PM emissions by

retrofitting, retiring, or replacing the bus engines. Staff assumes that transit

agencies will retrofit newer engines, retire older buses, and repower older buses

with new engines under this proposal.

In the original rule, retrofit devices that reduce diesel PM by 85 percent or more

were to be installed on engines beginning in 2002. By January 1, 2003, all pre-
57

1991 MY engines (Tier 1) were to be retrofitted. Tier 2 engines, comprising 1991

to 1995 MYs, were to be retrofitted in phases (Chapter II, Table 4), with the first

phase implemented as of January 1, 2003. The rule allowed for a one year delay

in retrofitting if no technology was available within six months of the applicable

compliance dates.

When no technology achieving an 85 percent PM reduction was verified by ARB

staff by January 1, 2002 for any pre-1994 MY or two-stroke engine, staff

concluded that the benefits of the rule would be less than expected. Staff

evaluated the status of the technology and, at the March 21, 2002 meeting of the

Board, staff reported that it did not expect to see any 85 percent diesel PM

reduction technology verified for these older engines in 2002, and possibly not in

the near future. The Board directed staff to revise the rule to recapture the diesel

PM reductions that were not going to be achieved because of the lack of verified

PM reduction technology for older bus engines.

The proposed amendments achieve slightly more emissions reductions after

2005, compared to the original regulations. Prior to 2005, the benefits will be

less than the original regulation. Two factors account for the smaller emission

reductions prior to 2005: the lack of technology to retrofit older engines now, and

the need to provide transit agencies additional time to obtain funding to replace

older engines.

The proposed amendments seek to balance the need to reduce diesel PM

emissions as much as technologically feasible with the need for flexibility in

achieving those reductions. A mandatory progressive reduction in total diesel

PM emissions will require transit agencies to use a variety of approaches to

strike a balance between retiring the oldest buses, repowering buses that have

remaining useful life, and retrofitting the newer buses (1994 MY and newer

engines) for which there are verified diesel emission reduction devices. Although

the minimum useful life for a transit bus is twelve years, transit agencies report

that many of the oldest buses are kept much longer. Providing for a flexible

implementation schedule will allow transit agencies the time necessary to replace

these older buses, or repower them.

The ARB staff estimates that the proposed amendments will reduce PM

emissions statewide in 2010 by approximately 180 lbs/day (33.4 tons per year).

Staff recalculated the baseline emissions from transit buses using an improved

model and better data. New information received from transit agencies in 2001

and 2002 showed that the transit bus population was significantly lower than

assumed for the original staff report. In addition, emission factors and annual

mileage have changed, based on research into emissions and reports from

transit agencies. Finally, EMFAC 2001 has been approved thus staff took this

opportunity to recalculate an improved baseline inventory on which to base the

analysis for these proposed amendments (see Appendix E).
58

With no PM retrofit and only emission reductions from new transit bus engine

standards, the total statewide PM emissions would be 300 lbs/day in 2005 and

239 lbs/day in 2010 (Baseline, Figure 4, Table 8). With full implementation of the

original rule, the statewide PM emissions would drop to 125 lbs/day in 2005 and

68 lb/day in 2010 (Current, Figure 4). With the proposed amendments, PM

emissions are 15 lbs/day higher in 2005 than was expected with the current rule,

and 12 lbs/day lower by 2010 (Proposed, Figure 4). In devising the scenario for

this comparison, staff assumed a ten percent allowance for delays and

exemptions from rule implementation.

Figure 4: Comparison of PM Emissions Scenarios

Table 8

Statewide Transit Bus PM Inventory Scenarios

(pounds per day)

Calendar

Year

Baseline

Inventory,

 No Retrofit

Current Regulation,

Fully Implemented

Proposed

Amendment

2005 300 125 140

2010 239 68 56

0

50

100

150

200

250

300

350

400

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Calendar Year

PM (lbs./day)

Baseline

Current

Proposed
59

The original rule included further emission reductions through the demonstration

and implementation of zero-emission bus programs beginning in 2003.

Combining the zero-emission bus requirement with more stringent NOx and PM

emission standards over the next several years, the original transit bus fleet rule

was expected to ensure a long-term solution to continued reduction in toxic air

contaminants. The proposed modifications will not change the long-term

requirements of the original rule or the benefits from the zero-emission bus

program. The zero-emission bus requirements will remain the same as adopted

in 2000.

2. HEB Interim Certification Procedure

HEBs are one technology that is available for transit agencies to purchase to

comply with the Public Transit Bus Fleet Rule. The procedure that certifies HEBs

does not itself produce emission benefits. Instead, certification is the method for

determining compliance with emission standards. Hence, no air quality benefits

have been calculated or considered to be associated with approval of staff’s

proposed interim certification procedure for HEBs.

B. Environmental Justice

The proposed amendments provide urban transit agencies with greater flexibility

to meet current regulations and were designed to achieve PM emission

reductions similar to those anticipated in the February 2000 rulemaking. The

proposed amendments regulate all transit agencies throughout the state to

ensure that emission benefits are achieved for all Californians. In addition, urban

transit buses transport people every day to destinations in various communities

throughout California; hence, environmental impacts resulting from the proposed

amendments would affect all communities where urban transit buses travel.

C. Cost-Effectiveness

1. PM Emission Reduction Proposal

The goal of the proposed amendments is to achieve benefits that are as close as

possible to those anticipated in the February 2000 rulemaking. The estimated

costs to transportation planning agencies, commissions, and transit agencies

would be about $2.5 million per year to comply with the requirements in the

February 2000 rulemaking. Total estimated costs per bus ranges from about

$3,000 to $10,000 dollars. Furthermore, the cost-effectiveness for the PM retrofit

requirements average about $17.90 per pound of PM reduced annually from

2003 to 2009.
60

Staff has determined that while costs per bus would remain within the same

range for implementation of the proposed amendments, the cost per pound of

PM reduced (cost-effectiveness) may increase. The cost-effectiveness each

year from 2003 to 2009, based on the median cost option (Appendix F), would

range from $13.67 to 32.77 per pound of PM reduced, with an average costeffectiveness of $25.23 per pound (Table 9). Staff also calculated a low cost

scenario, which resulted in an average cost-effectiveness of $10.91 per pound,

and a high cost scenario, which resulted in an average cost-effectiveness of

$44.51 per pound of PM reduced.

Table 9

Average Cost-Effectiveness

2003 - 2009

Low Cost Median Cost High Cost

Cost per Pound $10.91 $25.23 $44.51

The original cost-effectiveness of $17.90 per pound is within the range of the

recalculated cost-effectiveness range for these amendments. The slightly higher

estimated cost-effectiveness for these amendments is caused by a combination

of revised assumptions regarding emission benefits and costs (for example the

lifetime of the DPF, the number of buses that would be retrofitted each year, and

the cost of maintenance of the DPF). In determining the revised costeffectiveness, staff used the updated EMFAC 2001 model and the updated

transit bus inventory, which are based on reports from transit agencies.

Staff assumed that the current cost of a DPF is $5,500 and the future cost could

be as low as $1,100. A median cost of $3,000 was used as an average of

current and future costs to calculate the median average cost-effectiveness over

the life of the rule. Staff also assumed that only model year 1994 through 2002

engines would be retrofitted, as these are the only engines from which verified

technology is available. Staff has determined that it is unlikely that a DPF would

be available for older buses. While older buses could be retrofitted with oxidation

catalysts, most older transit buses have already been retrofitted under the U.S.

EPA Urban Bus Retrofit/Rebuild Program. Those that have not yet been

retrofitted with an oxidation catalyst represent a small portion of the urban buses.

Newer buses would also not be retrofitted. Bus engines produced after

October 1, 2002, are required to meet an engine standard for PM of

0.01 g/bhp-hr which requires use of a particulate filter.

Transit agencies may also retire their oldest buses, and replace engines in buses

with remaining useful life with newer engines (repower). An engine repower may

also extend the useful life of a bus if additional improvements are made at the
61

same time as the engine repower. Staff did not count the cost of bus retirement

in this cost-effectiveness calculation as staff anticipates that those buses retired

will have already exceeded their useful Federal minimum lifetime. Transit

agencies have access to Federal funds for 80 to 83 percent of the cost of new

buses, with State and local funding making up the balance of the cost. Likewise,

a repower can qualify for Federal, State, and local funds, with 50 to 100 percent

of the cost being covered (Appendix F, Table 1). In either bus retirement or

engine repower the transit agency realizes significant savings in fuel economy

and maintenance. Over the life of the engine, these savings often pay for the

portion of the cost that is not covered by Federal funding. Consequently, staff did

not include the cost of bus retirement or engine repower in calculating costeffectiveness.

As with the original regulation, the cost-effectiveness of the proposed

modifications does not include the value of health benefits associated with a

reduction in exposure to a toxic air contaminant. While assessing the health

benefits of PM control continues to be an important part of the ARB’s risk

management process, the benefits of the proposed transit rule modifications are

not part of this cost-effectiveness determination.

2. HEB Interim Certification Procedure

When staff proposes rules that set new technology enforcing standards, costs

associated with compliance of the standards are typically calculated. In

February 2000, when staff proposed the rules setting future more stringent

standards for urban transit buses and the fleet rule for public transit agencies,

HEBs were considered a future control technology available for transit agencies

to achieve the standards. However, no certification procedures were available to

certify HEBs at the time the rule was approved.

The proposed interim certification for HEBs is voluntary. Staff’s proposal

provides manufacturers with an approach for certifying full emission benefits of

HEBs. Furthermore, certified HEBs provide transit agencies with another control

option for complying with the already approved Public Transit Bus Fleet Rule.

Because the interim certification procedure is not setting new emission standards

and thus no direct emissions benefits are associated with the proposal, no

traditional cost-effectiveness can be calculated. Since staff’s proposal for

certifying HEBs is considered voluntary, there will be no economic impacts

associated with reasonable compliance with interim certification of HEBs.
62

IX. SUMMARY AND STAFF RECOMMENDATION

A. Summary of Staff’s Proposal

As presented in the previous chapters, ARB staff’s proposed modifications to the

Public Transit Fleet Rule are designed to reduce PM emissions to a level as

close as possible as those anticipated from the already approved February 2000

Public Transit Fleet Rule. Furthermore, they are designed to provide transit

agencies with additional flexibility in meeting PM retrofit requirements by allowing

transit districts to achieve a PM emission reduction from its January 1, 2002, total

PM emission baseline. The proposed amendments allow transit agencies in the

South Coast the opportunity to switch from the diesel path to the alternative fuel

path. Lastly, the proposed modifications introduce new definitions for clarification

of already adopted fleet rule, and an interim certification procedure for HEBs.

B. Staff Recommendation

The ARB staff recommends that the Board adopt modifications to 1956.1,

1956.2, 1956.4, 1956.8, and 2112, title 13, California Code of Regulations, and

the new incorporated “California Interim Certification Procedures for 2004 and

Subsequent Model Hybrid-Electric Vehicles, in the Urban and Heavy-duty

Vehicle Classes.” The modifications to the regulations are set forth in the

proposed regulation Order in Appendix A. The proposed incorporated test

procedures for HEBs are set forth in Appendix B.
63

X. REFERENCES

ARB 1999. Proposed regulation for a public transit bus fleet rule and emission

standards for new urban buses. Staff Report: Initial Statement of Reasons.

December 10, 1999.

ARB 2000. Risk Reduction Plan to Reduce Particulate Matter Emissions from

Diesel-Fueled Engines and Vehicles. Final. October 2000.

ARB 2001. The public transit bus fleet rule status report. September 20, 2001.

ARB 2002. Status report: public transit bus fleet rule. March 2002.

Federal Transit Administration. 2001. National Transit Database: Glossary of

transit terminology as defined for NTD reporting – 2001. (Internet 11/19/2001).

SAE. J2711, Recommended Practice for Measuring Fuel Economy And

Emissions Of Hybrid-Electric And Conventional Heavy-Duty Vehicles, April 2002.