TECHNICAL SUPPORT DOCUMENT: 

PROPOSED REGULATION FOR IN-USE ON-ROAD DIESEL VEHICLES 

Mobile Source Control Division 

Heavy-Duty Diesel In-Use Strategies Branch 

October 2008 

State of California 

AIR RESOURCES BOARD 

TECHNICAL SUPPORT DOCUMENT: 

REGULATION FOR IN-USE ON-ROAD DIESEL VEHICLES 

Public Hearing to Consider 

ADOPTION OF THE PROPOSED REGULATION FOR 

IN-USE ON-ROAD DIESEL VEHICLES 

To be considered by the Air Resources Board at a two-day meeting of the Board that 

will commence December 11, 2008, and may continue to December 12, 2008, at 

California Environmental Protection Agency 

Air Resources Board 

Byron Sher Auditorium 

1001 I Street 

Sacramento, CA 95814 

Mobile Source Control Division: 

Robert Cross, Chief 

Heavy-Duty Diesel In-Use Strategies Branch: 

Erik White, Chief 

In-Use Control Measures Section: 

Tony Brasil, Manager 

This report has been prepared by the staff of the Air Resources Board. Publication 

does not signify that the contents reflect the views and policies of the Air Resources 

Board, nor does mention of trade names or commercial products constitute 

endorsement or recommendation for use. 

State of California 

AIR RESOURCES BOARD 

PROPOSED REGULATION FOR IN-USE ON-ROAD VEHICLES 

Contributing Authors 

 Gloria Lindner Jessica Dean 

 Sherrie Sala-Moore Boons Baythavong 

 John Hironaka Nesamani Kalandiyrer 

 Barry Ho Mohan Krishnamurthy 

 Adam Gerber Joseph Gormley 

 Ron Nunes John Gruszecki 

 Jacqueline Johnson Mike Sutherland 

 Brandon Rose Pingkuan Di 

 Richelle Bishop Nicole Dolney 

 Todd Sax Reza Mahdavi 

 Jon Taylor Hien Tran 

 Kathy Jaw Seungju Yoon 

 Matthew Malchow Krista Fregoso 

 Earl Landberg Ben Ly 

 Peter Christensen David Kennedy 

 Corey Bock Alvaro Alvarado 

 Cherie Rainforth Lisa Williams 

 

Legal Counsel 

Michael Terris, Office of Legal Affairs 

Supporting Divisions 

Planning and Technical Support Division 

Research Division 

Stationary Source Division 

Acknowledgements 

This report was prepared with the assistance and support from the other divisions and 

offices of the Air Resources Board. In addition, we would like to acknowledge the 

assistance and cooperation that we have received from many individuals and 

organizations. 

i 

TABLE OF CONTENTS 

I. Overview and Recommendation ....................................................................... 1

A. INTRODUCTION ....................................................................................................... 1

B. OVERVIEW.............................................................................................................. 2

C. RECOMMENDATION ................................................................................................. 7

D. REFERENCES.......................................................................................................... 7

II. Regulatory Authority.......................................................................................... 9

III. Public Outreach and Environmental Justice.................................................. 13

A. ENVIRONMENTAL JUSTICE...................................................................................... 13

B. OUTREACH EFFORTS ............................................................................................ 13

C. FUTURE EFFORTS ................................................................................................. 16

D. REFERENCES........................................................................................................ 17

IV. Need for Emission Reductions........................................................................ 19

A. OZONE AND ITS PRECURSORS................................................................................ 19

B. PARTICULATE MATTER .......................................................................................... 22

C. TOXIC AIR CONTAMINANTS .................................................................................... 25

D. HEALTH IMPACTS OF EXPOSURE TO DIESEL EXHAUST AND DIESEL PM ..................... 26

E. DIESEL PM RISK REDUCTION................................................................................. 32

F. STATE IMPLEMENTATION PLAN COMMITMENTS ........................................................ 33

G. REFERENCES........................................................................................................ 34

V. Vehicle Descriptions and Manufacturers ....................................................... 39

A. OVERVIEW............................................................................................................ 39

B. VEHICLE CLASSES ................................................................................................ 39

C. ENGINE AND VEHICLE MANUFACTURERS................................................................. 40

D. VEHICLE TYPES .................................................................................................... 42

E. REFERENCES........................................................................................................ 54

VI. Estimated Emissions from On-Road Diesel Trucks and Buses ................... 57

A. METHODOLOGY .................................................................................................... 57

B. POPULATION AND ACTIVITY.................................................................................... 58

C. EMISSIONS RATES ................................................................................................ 68

D. STATEWIDE BASELINE EMISSIONS ESTIMATES ......................................................... 69

E. UPDATING EMFAC WITH THIS NEW ANALYSIS......................................................... 73

F. REFERENCES........................................................................................................ 74

VII. On-Road Diesel Retrofit Technology .............................................................. 75

A. DIESEL EMISSION CONTROL STRATEGIES ............................................................... 75
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B. VERIFICATION OF DIESEL EMISSION CONTROL STRATEGIES...................................... 83

C. LIST OF ARB VERIFIED TECHNOLOGIES .................................................................. 86

D. SUMMARY OF ON-ROAD INSTALLATIONS OF EXHAUST RETROFITS............................. 88

E. ANTICIPATED AVAILABILITY OF RETROFITS .............................................................. 92

F. REFERENCES........................................................................................................ 93

VIII. Current and Future Engine Technology ......................................................... 95

A. NEW ON-ROAD DIESEL ENGINE STANDARDS........................................................... 95

B. NEW DIESEL ENGINES........................................................................................... 99

C. AVAILABILITY OF VEHICLES WITH CLEANER ENGINES.............................................. 102

D. REPOWERS ........................................................................................................ 102

E. HYBRID VEHICLES............................................................................................... 103

F. ALTERNATIVE FUELED VEHICLES.......................................................................... 105

G. ALL ELECTRIC HEAVY-DUTY VEHICLES ................................................................. 106

H. REFERENCES...................................................................................................... 106

IX. Existing Diesel Emission Reduction Regulations ....................................... 109

A. IN-USE ON-ROAD DIESEL VEHICLE REGULATIONS ................................................. 109

B. IN-USE OFF-ROAD DIESEL VEHICLES AND EQUIPMENT .......................................... 112

C. PORTABLE ENGINES AND EQUIPMENT................................................................... 115

D. DIESEL FUEL STANDARDS.................................................................................... 116

E. OFF-ROAD ENGINE STANDARDS .......................................................................... 117

F. REFERENCES...................................................................................................... 119

X. Proposed Regulation for In-Use On-Road Diesel Vehicles......................... 121

A. PROPOSED REGULATION OVERVIEW..................................................................... 121

B. PURPOSE ........................................................................................................... 122

C. APPLICABILITY .................................................................................................... 122

D. DEFINITIONS....................................................................................................... 124

E. PERFORMANCE REQUIREMENTS........................................................................... 126

F. OTHER REQUIREMENTS....................................................................................... 131

G. SPECIAL PROVISIONS AND COMPLIANCE EXTENSIONS............................................ 134

H. REPORTING ........................................................................................................ 140

I. ELECTRONIC TRACKING SYSTEM .......................................................................... 141

J. RECORDKEEPING, RETENTION AND AUDITS ........................................................... 142

K. RIGHT OF ENTRY ................................................................................................ 142

L. DISCLOSURE OF REGULATION APPLICABILITY ........................................................ 143

M. PENALTIES ......................................................................................................... 143

XI. Proposed Changes to Other Diesel Emissions Control Regulations ........ 145

A. PROPOSED MODIFICATIONS FOR CRANES AND SWEEPERS ..................................... 145
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B. PROPOSED AMENDMENTS TO EXISTING REGULATIONS........................................... 147

C. CHANGES TO IDLING REQUIREMENTS FOR CERTAIN ON-ROAD VEHICLES ................ 152

XII. Environmental Impact .................................................................................... 153

A. LEGAL REQUIREMENTS........................................................................................ 153

B. REASONABLY FORESEEABLE ENVIRONMENTAL IMPACTS ........................................ 154

C. HEALTH BENEFITS ANALYSIS ............................................................................... 162

D. CLIMATE CHANGE IMPACTS.................................................................................. 165

E. WELFARE IMPACTS ............................................................................................. 168

F. REASONABLY FORESEEABLE MITIGATION MEASURES ............................................ 168

G. ALTERNATIVE MEANS OF COMPLIANCE WITH THE PROPOSED REGULATION .............. 168

H. REFERENCES...................................................................................................... 168

XIII. Cost Summary and Methodology.................................................................. 171

A. LEGAL REQUIREMENTS........................................................................................ 171

B. METHODOLOGY FOR ESTIMATING COSTS .............................................................. 171

C. REPORTING COST............................................................................................... 189

D. TOTAL STATEWIDE COSTS................................................................................... 190

E. COST EFFECTIVENESS OF THE PROPOSED REGULATION ........................................ 191

F. COST MODEL METHODOLOGY FOR INDUSTRY SECTORS......................................... 192

G. SENSITIVITIES IN ESTIMATING STATEWIDE COSTS.................................................. 194

H. REFERENCES...................................................................................................... 196

XIV. Economic Impacts.......................................................................................... 197

A. BACKGROUND..................................................................................................... 197

B. ECONOMIC IMPACTS ON THE CALIFORNIA ECONOMY .............................................. 198

C. ECONOMIC IMPACT ON INDIVIDUAL BUSINESS SECTORS ......................................... 200

D. ECONOMIC IMPACT ON CALIFORNIA CONSUMERS................................................... 226

E. REFERENCES...................................................................................................... 227

XV. Availability of Incentive Funding................................................................... 229

A. STATE SOURCES OF FUNDING.............................................................................. 229

B. HOW AN INTEGRATED GRANT AND LOAN PROGRAM COULD ASSIST FLEETS............. 240

C. FEDERAL FUNDING SOURCES .............................................................................. 241

D. LOCAL AGENCY PROGRAMS................................................................................. 242

XVI. Rationale for Regulatory Provisions and Changes to Other Regulations. 245

A. LOW USE EXEMPTION ......................................................................................... 245

B. FLEET AVERAGE AND BACT PERCENT LIMITS ....................................................... 245

C. DELAYS TO THE NOX PERFORMANCE REQUIREMENTS ........................................... 246

D. CAB OVER ENGINE TRACTORS WITH 57 FOOT TRAILERS ........................................ 253
iv 

E. SMALL FLEET PROVISIONS................................................................................... 253

F. CREDIT FOR HYBRID AND ALTERNATIVE FUEL VEHICLES ........................................ 254

G. ENFORCEABILITY PROVISIONS.............................................................................. 255

H. EXCLUSION OF PERSONAL USE MOTOR HOMES .................................................... 256

I. SAFETY CONSIDERATIONS ................................................................................... 256

J. SCHOOL BUSES .................................................................................................. 257

K. DRAYAGE (PORT) TRUCKS................................................................................... 259

L. TWO-ENGINE CRANES......................................................................................... 260

M. PRIVATELY-OWNED TWO-ENGINE STREET SWEEPERS........................................... 262

N. PRIVATELY-OWNED UTILITIES ALTERNATIVE PROPOSAL......................................... 263

O. WORKOVER RIGS................................................................................................ 264

P. OTHER CHANGES................................................................................................ 264

Q. REFERENCES...................................................................................................... 266

XVII. Enforcement.................................................................................................... 267

A. OVERVIEW.......................................................................................................... 267

B. PLANNED ENFORCEMENT ACTIVITIES FOR PROPOSED REGULATION ........................ 267

C. NEED FOR ADDITIONAL RESOURCES..................................................................... 269

XVIII. Alternative Considered .................................................................................. 271

A. RETROFIT ONLY REGULATION .............................................................................. 271

B. AUGUST 2007 ARB STAFF PROPOSAL ................................................................. 272

C. JANUARY 2008 ARB STAFF PROPOSAL ................................................................ 273

D. STREET SWEEPER INDUSTRY PROPOSAL .............................................................. 277

E. DRIVING TOWARD A CLEANER CALIFORNIA PROPOSAL........................................... 279
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LIST OF TABLES 

Table III-1: Public Workshop Dates and Locations.............................................. 14

Table III-2: Companies, Associations, and other Organizations Contacted......... 15

Table IV-1: State and National Ozone Ambient Air Quality Standards ................ 20

Table IV-2: State and National PM Ambient Air Quality Standards (μg/m3

)......... 23

Table IV-3: Substances in Diesel Exhaust Listed by California as Toxic Air 

Contaminants .................................................................................... 25

Table IV-4: Statewide Health Impacts Associated with In-Use On-Road Diesel 

Vehicles (Baseline Year 2008) .......................................................... 30

Table IV-5: Non-Cancer Health Impacts Associated with In-Use On-Road Diesel 

Vehicles Operating in the Southern California Study Area (2003 

Emissions)......................................................................................... 31

Table V-1: Weight Classification Defined by U.S. DOT....................................... 40

Table V-2: Common Manufacturer of On-Road Engines .................................... 40

Table V-3: Common Manufacturers of Trucks and Tractors ............................... 42

Table V-4: Common Manufacturers of Buses and Shuttle Buses....................... 42

Table VI-1: Data Sources Used to Develop Population and Activity Estimates ... 59

Table VI-2: 2008 Population, VMT, and VMT-Weighted Average Age by Inventory 

Category, Fleet Size, and Mileage Thresholds.................................. 60

Table VI-3: Percentage of Population and VMT by Vehicle Type ........................ 63

Table VI-4: Distribution of Population and VMT by Mileage Threshold (2008)..... 64

Table VI-5: Fraction of Miles Traveled in California for Out-of-State Categories . 65

Table VI-6: Statewide Emissions by Truck and Bus Inventory Category (2008).. 70

Table VI-7: Baseline Emissions by Fleet Size and Mileage Threshold (2008)..... 71

Table VI-8: Statewide PM and NOx Baseline Emissions ..................................... 71

Table VII-1: Passive DPF...................................................................................... 77

Table VII-2: Wall Flow Filter.................................................................................. 78

Table VII-3: Active DPF ........................................................................................ 79

Table VII-4: Fuel-Water Emulsion......................................................................... 80

Table VII-5: Diesel Emission Control Strategy Warranty Period ........................... 84

Table VII-6: Diesel Emission Control Strategy Verification Levels (as adopted by 

the Board in January 2008) ............................................................... 85

Table VII-7: Verified Level 3 DECS (as of October 2008)..................................... 87

Table VII-8: Verified Level 2 DECS (as of October 2008)..................................... 87
vi 

Table VII-9 Summary of Carl Moyer Projects....................................................... 89

Table VIII-1: U.S. EPA Heavy-Duty Diesel Engine Emission Standards................ 96

Table VIII-2: Exhaust Emission Standards and Phase-In Schedule for 2007 and 

Later Model Year Heavy-Duty Diesel On-Road Engines................... 97

Table IX-1: Regulations Requiring Retrofits of On-Road Diesel Vehicles.......... 110

Table IX-2: Implementation Schedule for Most Municipal and Utility Fleets 

Vehicles........................................................................................... 112

Table IX-3: Regulations for In-Use Off-Road Diesel Vehicles............................ 113

Table IX-4: TRU In-Use Performance Standards............................................... 115

Table IX-5: ARB and U.S. EPA Off-Road Compression-Ignition (Diesel) Standards 

(NMHC+NOx/CO/PM in g/bhp-hr where applicable) ....................... 118

Table X-1: Best Available Control Technology Compliance Schedule.............. 126

Table X-2: Percent of Fleet That Must Comply with PM and NOx BACT Standard128

Table X-3: PM Emissions Factors by Engine Model Year (g/mile).................... 129

Table X-4: NOx Emissions Factors by Engine Model Year (g/mile).................. 129

Table X-5: Fleet Targets for PM and NOx (g/mile)............................................ 130

Table X-6: PM and NOx Equivalency Standards .............................................. 131

Table X-7: Proposed PM BACT Schedule for School Buses ............................ 132

Table X-8: Agricultural Vehicle Mileage Threshold ........................................... 135

Table XII-1: Emission Benefits from Implementation of the Proposed Regulation155

Table XII-2: Statewide PM Emissions Benefits from the Proposed Regulation... 156

Table XII-3: Statewide NOx Emissions Reductions from the Proposed Regulation157

Table XII-4: South Coast SIP Emission Reduction Targets for Trucks ............... 159

Table XII-5: San Joaquin SIP Emission Reduction Targets for Trucks ............... 159

Table XII-6: Total Health Benefits Associated with Reductions in Emissions from 

the Implementation of the On-Road Truck and Bus Regulation (2010-

2025)*.............................................................................................. 163

Table XIII-1: PM Filter Costs................................................................................ 175

Table XIII-2: Average Vehicle Replacement Age by Average Fleet Age Group... 176

Table XIII-3: Statewide Weighted Average Vehicle Replacement Age ................ 177

Table XIII-4: In-state Heavy-Heavy Duty Vehicles by Fleet Age for Fleets with more 

than 3 vehicles (excluding fleets qualifying for special provisions).. 182

Table XIII-5: Vehicles by Fleet Average Age ....................................................... 183

Table XIII-6: Summary of Average Increased Capital Costs................................ 184
vii 

Table XIII-7: Cumulative Increased Retrofit Maintenance Costs ($2008) ............ 187

Table XIII-8: Initial Reporting Costs (2010).......................................................... 189

Table XIII-9: Total Annual Reporting Costs.......................................................... 190

Table XIII-10: Total Reporting Costs...................................................................... 190

Table XIII-11: Summary of Average Increased by Statewide Fleet Groups........... 191

Table XIII-12: Comparison of the Average Cost-Effectiveness of the Proposed 

Regulation to Average Cost Effectiveness of Recently Adopted Air 

Toxic Control Measures................................................................... 192

Table XIII-13: Increased Costs by Business Sector............................................... 194

Table XIII-14: Cost Sensitivity Analysis for Use of NOx Retrofits........................... 195

Table XIII-15: Cost Sensitivity Analysis for Increased Retrofit Costs ..................... 195

Table XIV-1: Estimates of Total Capital Costs of Proposed Regulation by Affected 

Industries in 2013 (Millions of 2008 Dollars).................................... 199

Table XIV-2: Impact on the California Economy of Proposed Regulation in the Year 

2013 (Billions of 2006 Dollars)......................................................... 200

Table XIV-3: 2008 Land Line Reader Survey Results on Gross Income per Mile 206

Table XIV-4: Percentage of Transportation Fleets Reporting Equipment HP Subject 

to Other Rules ................................................................................. 210

Table XIV-5: Total Off-Road Vehicle Fleet Characteristics................................... 216

Table XIV-6: Percent of Vehicles in Construction by Category ............................ 216

Table XV-1: Proposed Carl Moyer Program Guidelines Changes....................... 235

Table XV-2: Future Carl Moyer Program On-Road Funding Options .................. 236

Table XV-3: Credit Risk....................................................................................... 238

Table XVI-1: Emissions Comparison of Low Mileage Vehicle and Typical Fleet 

in 2014............................................................................................. 247

Table XVI-2: Alternatives Emission Loss Compared to Staff Proposal (tpd) ........ 248

Table XVI-3: Specialty Agricultural Vehicle Population Estimates........................ 251

Table XVI-4: Distances from the Facility Boundary wherein the Risk is 10 in a 

Million for Different Agricultural Vehicle Volumes............................ 252

Table XVIII-1: August 2007 ARB Staff Proposed BACT Schedule......................... 272

Table XVIII-2: January 2008 ARB Staff Proposed BACT Schedule ....................... 274

Table XVIII-3: January 2008 ARB Staff Proposed Compliance Schedule for Small 

Fleets............................................................................................... 275

Table XVIII-4: NAPSA July 2008 Proposal for Street Sweepers ............................ 278

Table XVIII-5: DTCC Proposal for Mileage Exemptions......................................... 280
viii 

Table XVIII-6: DTCC Proposed BACT Schedule.................................................... 281

Table XVIII-7: DTCC Proposed BACT Percent Limits............................................ 282
ix 

LIST OF FIGURES 

Figure IV-1: Federal and State Area Designations for Ozone............................... 21

Figure IV-2: Federal and State Area Designations for PM2.5 ............................... 24

Figure IV-3: State Average Potential Cancer Risk from Outdoor Ambient Levels of 

Toxic Pollutants for the Year 2000,,

................................................... 28

Figure V-1: Market Shares of Diesel Engine Manufacturers ................................ 41

Figure VI-1: The Historic and Projected Relationship between VMT and GDP on a 

Nationwide Level............................................................................... 66

Figure VI-2: Estimated Future New Vehicle Sales by Calendar Year ................... 67

Figure VI-3: California Statewide NOx Emissions from Trucks, Baseline 2008-202372

Figure VI-4: California Statewide PM2.5 Emissions from Trucks, Baseline 2008-

2023 .................................................................................................. 72

Figure VI-5: California Statewide CO2 Emissions from Trucks, Baseline 2008-202373

Figure VII-1: Wall Flow Filter.................................................................................. 76

Figure VII-2: Flow Through Filter ........................................................................... 79

Figure VII-3: Cleaire Longview Lean-NOx Catalyst System................................... 82

Figure VII-4: Johnson Matthey SCRT System ....................................................... 83

Figure VII-5: Under Chassis Horizontal DPF Muffler Installation............................ 89

Figure VII-6: Horizontal DPF Installation for Vertical Exhaust................................ 90

Figure VII-7: Donaldson Horizontal DPF Installation on School Bus...................... 90

Figure VII-8: Vertical DECS Installations on Tanker and Tractor ........................... 91

Figure VII-9: Vertical SCRT® System on Tractor – 50 to 90 percent NOx reduction92

Figure VIII-1: Vehicle with Oversized Fuel Tank to Accommodate the Lower Energy 

Density of Alternative Fuels............................................................. 106

Figure X-1: NOx Exempt Areas of California...................................................... 137

Figure XII-1: Projected PM Emissions With and Without the Regulation ............. 156

Figure XII-2: Projected NOx Emissions With and Without the Regulation............ 157

Figure XII-3: Statewide CO2 Baseline and With Regulation Emissions................ 166

Figure XIII-1: In-state Heavy-Heavy Duty Vehicle Age Distribution....................... 173

Figure XIII-2: Example Vehicle Prices (in thousands of dollars)............................ 174

Figure XIII-3: Annual Compliance Flowchart......................................................... 179

Figure XIII-4: Average Increased Cost for In-state Heavy-Heavy Duty Vehicles in 

Fleets with 4 or more Vehicles (excluding special provisions)......... 180
x 

Figure XIII-5: Average Increased Cost for In-state Medium-Heavy Duty Vehicles in 

Fleets with 4 or more Vehicles (excluding special provisions)......... 181

Figure XIII-6: Average Increased Cost for In-state Heavy-Heavy Duty Low Use NOx 

Exempt Vehicles (<7500 Miles)....................................................... 181

Figure XIII-7: Number of DPFs in Statewide Fleet Resulting from Proposed 

Regulation ....................................................................................... 186

Figure XIII-8: Estimated Fuel Economy of Diesel Vehicles by Vehicle Model Year188

Figure XIII-9: Percentage of Vehicle Population by Business Sector from National 

2002 VIUS Data .............................................................................. 193

Figure XIV-1: Vehicles from Non-Neighboring States ........................................... 203

Figure XIV-2: California IRP .................................................................................. 204

Figure XIV-3: California In-state Registered Tractors............................................ 205

Figure XIV-4: California Interstate Registered Owner Operators........................... 206

Figure XIV-5: In-state Registered Owner Operator Tractors (Excluding Low Mileage 

Vehicles).......................................................................................... 207

Figure XIV-6: California Gross Domestic Product: Truck Transportation.............. 208

Figure XIV-7: California Employment: Transportation and Warehousing ............. 209

Figure XIV-8: California Gross Domestic Product: Agriculture ............................. 213

Figure XIV-9: California Employment: Agriculture ................................................ 213

Figure XIV-10: California Gross Domestic Product: Construction .......................... 217

Figure XIV-11: California Employment: Construction ............................................. 218

Figure XIV-12: California Construction Total Valuation Dollars (in billions) ............. 219

Figure XIV-13: California Gross Domestic Product: Manufacturing........................ 222

Figure XIV-14: California Employment: Manufacturing........................................... 222

Figure XIV-15: California Gross Domestic Product: Retail and Wholesale Trade .. 224

Figure XIV-16: California Employment: Retail and Wholesale Trade ..................... 224

Figure XV-1: Proposition 1B Fiscal Year 2007/2008 Allocation............................ 231

Figure XVI-1: Number of Vehicles by Fleet Size (California Department of Motor 

Vehicles, 2006)................................................................................ 254

Figure XVI-2: California K-12 Students Transported at Public Expense................ 259

Figure XVI-3: NOx Emissions Benefits of Staff Proposal....................................... 261

Figure XVI-4: PM Emissions Benefits of Staff Proposal ........................................ 262

Figure XVI-5: NOx Emissions with Staff Proposal ................................................. 263

Figure XVIII-1: August 2007 ARB Staff Proposed Fleet Average PM and NOx 

Emission Targets............................................................................. 273
xi 

Figure XVIII-2: January 2008 ARB Staff Proposed Fleet Average Emission Targets275

Figure XVIII-3: ARB January Proposal (NOx Emissions) ........................................ 276

Figure XVIII-4: ARB January Proposal (PM Emissions) .......................................... 277

Figure XVIII-5: DTCC Stakeholder Proposal (NOx Emissions) ............................... 283

Figure XVIII-6: DTCC Stakeholder Proposal (PM Emissions) ................................. 283
xii 
xiii 

APPENDICES 

 A. Proposed Regulation for In-Use On-Road Vehicles

 A1. Outline of Proposed In-Use On-Road Diesel Vehicle Regulation 

 B. Proposed Amendments to Existing Diesel Regulation 

 C. Public Outreach 

 D. Health Impacts from Off-Road Diesel Vehicles 

 E. Health Risk Assessment Methodology 

 F. Tactical Support Vehicle Letter 

 G. Emissions Inventory – Methodology and Results 

 H. Exhaust Retrofit Technologies 

 I. School Bus Regulatory Requirements 

 J. Cost and Economic Analysis Methodology 

 K. School Bus Cost Methodology 

 L. Requirements of Two-Engine Cranes 

 M. Street Sweeper Vehicles 

 N. Regulatory Alternatives 

 O. List of Acronyms 
xiv 
-1- 

I. OVERVIEW AND RECOMMENDATION

A. Introduction 

The California Air Resources Board's (ARB or Board) mission is to protect public health, 

welfare, and ecological resources through the effective and efficient reduction of air 

pollutants, while recognizing and considering the effects on the economy of the State 

(ARB, 2002). ARB’s vision is that all individuals in California, especially children and 

the elderly, can live, work, and play in a healthful environment – free from harmful 

exposure to air pollution. To achieve this, ARB has adopted numerous regulations to 

control emissions from many different sources, including diesel engines. Reducing 

health risk from diesel particulate emissions is one of the Board's highest priorities. 

Diesel engine exhaust is a health concern because it is a source of unhealthful air 

pollutants including gaseous and particulate-phase toxic air contaminants (TAC), 

particulate matter (PM), oxides of nitrogen (NOx), carbon monoxide, and hydrocarbons. 

Reducing health risk from diesel particulate emissions is one of the Board's highest 

priorities. 

Staff is proposing a regulation to reduce emissions from in-use on-road diesel vehicles. 

Such vehicles include various types and sizes of trucks that haul products throughout 

the state, vehicles used in agricultural operations, and drayage trucks used at 

California’s ports and intermodal rail facilities. 

Staff is also proposing a number of changes to existing in-use diesel vehicle and engine 

regulations to reduce overlapping requirements for the same vehicles, to clarify a 

number of issues with the existing regulations, to provide additional compliance 

flexibility, and to generally improve enforceability of the existing regulations. 

This technical support document is an addendum to the Initial Statement of Reasons 

and includes the following chapters: 

• Background information, the purpose of the regulation (Chapter I) 

• ARB’s legal authority to adopt the regulation (Chapter II); 

• Summary of outreach to inform the public and solicit public participation in the 

development of the proposed regulation (Chapter III); 

• Discussion of the need for control of diesel PM and NOx from in-use on-road diesel 

vehicles (Chapter IV); 

• Discussion of the various types of vehicles subject to the proposed regulation and 

their manufacturers (Chapter V); 

• Describes the emissions inventory that was developed for the proposed regulation 

(Chapter VI); 

• Discussion of retrofit strategies available for reducing diesel emissions from in-use 

on-road vehicles (Chapter VII); 

• Discussion current and future engine technologies that will be available to meet the 

NOx and PM performance standards (Chapter VIII); 
-2- 

• Summaries of the requirements of ARB’s regulations that reduce the emissions and 

risk from new and existing on-road and off-road diesel engines as well as portable 

engines and equipment (Chapter IX); 

• Summary and discussion of the proposed regulation (Chapter X); 

• Discussion of modifications proposed for a number of existing ARB diesel 

regulations (Chapter XI); 

• Environmental impact of the proposed regulation (Chapter XII); 

• Discussion of the statewide cost of the proposed regulation and on affected 

business sectors (Chapter XIII); 

• Discussion of the economic impact of the proposed regulation on the economy of the 

state and on certain affected business sector (Chapter XIV); 

• Discussion of availability of incentive funding (Chapter XV); 

• Discussion of the rationale for proposing special provisions, such as the 

requirements for small fleets and the less stringent requirements for low mileage 

thresholds (Chapter XVI); 

• Discussion of preliminary plans for enforcement (Chapter XVII); 

• Alternatives considered and the reasons they were not chosen over the proposed 

regulation (Chapter XVIII); and 

• Proposed text of the regulation and other supplementary information (Appendices). 

B. Overview 

Staff of the Air Resources Board (ARB or Board) is proposing a regulation that would 

reduce emissions of diesel particulate matter (PM) and oxides of nitrogen (NOx) from 

over 400,000 diesel vehicles registered in the State, and another half a million out-ofstate vehicles that visit California each year. The regulation would achieve these 

emission reductions by requiring fleet owners to modernize their fleets and install 

exhaust retrofits. The regulation is projected to achieve significant emission reductions, 

but at a significant cost to affected fleets. 

The scope of the proposed regulation is broad. It would affect about 170,000 California 

businesses (including over 150,000 small businesses) in most sectors of the State’s 

economy, and almost a million vehicles. Some common industry sectors that operate 

trucks and buses subject to the regulation include: for-hire transportation, construction, 

manufacturing, retail and wholesale trade, vehicle leasing and rental, bus lines, and 

agriculture. Within each of these broad sector categories, there is a wide variety of 

vehicle types. The potential impact of this regulation on various business sectors 

depends on the number, type and age of the affected vehicles operated by each sector. 

A copy of the regulation is provided in Appendix A, and a simplified summary is 

provided in Appendix A1. 

The proposed new regulation would apply to any person, business, or federal 

government agency that owns or operates affected vehicles in California. Affected 
-3- 

vehicles include heavy-duty diesel-fueled vehicles with a gross vehicle weight rating 

(GVWR) greater than 14,000 pounds, yard trucks with off-road certified engines and 

certain diesel-fueled shuttle vehicles regardless of weight. The proposed regulation 

would be applicable regardless of where the vehicle is registered. However, the 

proposed regulation would not apply to military tactical support vehicles, authorized 

emergency vehicles, or private motor homes not used for commercial purposes. 

In general, the regulation would require owners to reduce PM and NOx emissions from 

their fleets by upgrading the vehicles to meet specific performance standards for these 

pollutants (defined as best available control technology, or BACT). The BACT standard 

for PM is generally an engine equipped with a diesel particulate filter, and the BACT 

standard for NOx is an engine newly manufactured in 2010 or later. A fleet may meet 

these performance requirements by retrofitting a vehicle with a verified diesel emission 

control strategy (DECS)1

 that will achieve PM or NOx reductions or both as required, 

replacing an engine with a newer cleaner one, or replacing a vehicle with one having a 

cleaner engine. This replacement vehicle can be either new or used. 

The proposed regulation begins in 2010, and requires the installation of verified PM 

DECS on certain vehicles depending on their model year. Then, beginning in 2012, 

fleets would need to begin replacing their vehicles with newer used or new vehicles that 

meet the most stringent 2010 model year engine emission standards. Through this, by 

the beginning of 2014, nearly all on-road diesel engines operating in California will 

either have a verified DECS installed, or will be engines that came with a diesel 

particulate filter (DPF) from the engine manufacturer. Then, between 2012 and 2022, 

the remaining older vehicles would be need be replaced such that by 2023, all on-road 

diesel vehicles operating in California would have the cleanest engines available - that 

is, they would meet the 2010 model year emission standards. 

Each year, the proposed regulation provides three options for complying with the 

performance requirements. First, a fleet could retrofit and replace vehicles in its fleet, 

according to a prescriptive schedule, based on each vehicle’s engine model year. 

Second, a fleet could meet a limit that sets an annual cap on the number of retrofits to 

be installed and the minimum number of engines replaced required to meet the 2010 

engine requirements each year. Third, a fleet could meet a fleet average option, with 

targets that decline over time. Each fleet has the flexibility to meet any one of these 

options each year, and is not required to meet the same option for both pollutants. That 

is, a fleet could met the BACT schedule for PM, but meet the fleet average for NOx, and 

be fully compliant with the proposed regulation. 

The proposed regulation also contains special provisions to address the unique issues 

facing small fleets. Under staff’s proposal, small fleets, those with one to three vehicles, 

are exempt from any clean up requirements until 2012. Then, in 2013, small fleets 

would need to show they cleaned up one vehicle to a lesser requirement. That vehicle 

 

1

 A retrofit device that has been verified under ARB’s Verification Procedure, which ensures 

the effectiveness and durability of diesel engine retrofits. 
-4- 

would then not need to meet the 2010 engine requirement until 2018. In fleets of two or 

three, additional time is then provided for the second or third vehicle to meet the PM 

and NOx performance requirements. 

Because of the wide variety of fleets and vehicles subject to the proposed regulation, 

certain special provisions have been included. First, the proposed regulation would 

exempt certain lower use vehicles from some or all of the clean up requirements. The 

proposed regulation would establish requirements to clean up diesel PM emissions from 

school buses, although it would not require the replacement of any school buses newer 

than 1977. Also, special provisions would be provided for unique vehicles and certain 

types of agricultural vehicles. The regulation would provide credits for actions which 

reduce emissions from these vehicles earlier than required, as well as for the early 

adoption of hybrid vehicle technology and for the use of alternative fuels. Staff is also 

proposing to address a number of regulatory issues with two-engine cranes and twoengine street sweepers which are subject to a number of different ARB regulations. 

To aid in its enforcement, the proposed regulation would impose certain reporting and 

recordkeeping requirements. The proposed regulation would also establish 

requirements for any in-state or out-of-state motor carrier, California based broker, or 

any California resident who hires or dispatches vehicles subject to the regulation. Also, 

California sellers of vehicles are subject to the proposed regulation and would have to 

disclose the regulation’s potential applicability to buyers of the vehicles. 

The proposed regulation would provide significant diesel PM and NOx emissions 

reductions that would have a substantial positive air quality impact throughout 

California. By reducing emissions of pollutants that contribute to elevated ambient 

levels of particulate matter and ozone, the regulation would help achieve attainment of 

the federal and state clean air standards for PM and ozone. In 2020, the regulation is 

expected to reduce diesel PM2.5 emissions by 5.2 tons per day and NOx emissions by 

about 79 tons per day statewide, which represents a 43 percent reduction in diesel PM 

and a 23 percent reduction in NOx from emission levels that would be anticipated in the 

absence of the regulation. In addition, the proposed regulation would provide a slightly 

positive change in emissions of greenhouse gases, and would reduce emissions of 

black carbon – a component of diesel PM and a likely contributor to global warming. 

In addition, the proposed regulation is the critical piece in California’s efforts to meet 

federal clean air standards. In 2007, the State approved its blueprint to attain the 

federal clean air standard for fine particulate (PM2.5) and ozone. This document, 

known as the State Implementation Plan or SIP, committed to significant emission 

reductions from vehicles operating throughout the state, in particular in the South Coast 

and San Joaquin Valley air basins. The proposed regulation would meet or exceed the 

combined NOx and PM2.5 SIP fleet rule targets in both the South Coast and San 

Joaquin Valley air basins for all years. In 2014, in the South Coast Air Basin, the SIP 

target would be met by achieving slightly more PM2.5 reductions and slightly less NOx 

than expected. The proposed regulation would also help achieve the SIP reduction 
-5- 

goals in 2020 for attainment in regions downwind of the South Coast and the San 

Joaquin Valley air basins. 

Also, significant additional health benefits would also be obtained with the reductions of 

ambient levels of diesel PM. The emission reductions from the regulation are expected 

to prevent approximately 9,400 premature deaths over the course of the regulation 

(2,800 to 17,000, 95 percent confidence interval), and would result in about 150,000 

fewer asthma-related cases and 950,000 fewer lost work days. The economic valuation 

of these health benefits is estimated to range from $48 to $68 billion. 

However, while the proposed regulation would not quite achieve the overall goal set 

forth in the 2000 Diesel Risk Reduction Plan (RRP) of reducing diesel PM by 

85 percent, from 2000 baseline levels, staff projects that the proposed regulation would 

reduce in-use on-road vehicle diesel PM emissions from the 2000 baseline by 

80 percent in 2020. These reductions represent the maximum achievable reductions of 

diesel PM emissions from in-use on-road diesel vehicles. 

While the benefits of the proposed regulation are significant, so are the costs. Staff 

estimates that the total cost of the proposed regulation is about $5.5 billion, in 2008 

expenditure equivalent dollars (2008 dollars). Of this, about $4.5 billion will be incurred 

by California based fleets, and $1 billion will be borne by out-of-state fleet operators. 

These costs will be spread out over 16 years, from 2010 through 2025, with costs 

varying between years; in its highest year, 2013, the capital costs of the proposed 

regulation are expected to be about $566 million. Overall, about 40 percent of the cost 

of the proposed regulation is expected to be incurred directly by the transportation and 

warehousing industry, more than 20 percent by the construction industry, and about 10 

percent by the wholesale and retail trade industry. The remaining costs are spread 

among various other affected industries. 

Costs to individual fleets would vary depending on the size of each fleet, vehicle types, 

vehicle ages, and its normal purchasing practices. Costs also would vary depending on 

the compliance strategy chosen by each fleet (retrofit, repower, buy new, and/or buy 

used). For newer fleets, the costs will be minimal, while for older fleets that need to 

upgrade a significant number of vehicles, the cost will be significantly more substantial. 

The same holds true for small fleets, where some would experience no increased costs 

while others would experience higher costs. The total estimated cost over the lifetime of 

the regulation for small fleets is approximately $1.7 billion (2008 dollars). 

Staff expects many, if not most, affected businesses to pass through the proposed 

regulation’s costs to their customers. This could be achieved, for example, through 

higher shipping rates, or higher costs for manufactured goods, resulting in higher 

revenue (but not necessarily higher profits) for affected fleets. However, the ability to 

pass on costs will vary by business sector. While the overall impact on most business 

sectors covered by the proposed regulation is small, generally averaging less than one 

tenth of one percent of their overall gross domestic product, some companies may not 

be able to pass through these costs, and will have to absorb them out of their gross 
-6- 

revenues. While the extent of the ability for fleets to absorb the costs of the proposed 

regulation is unclear, this may likely impact the profitability of companies that cannot 

pass through their compliance costs. 

Despite affected fleets passing through these costs, consumers can expect to pay a 

negligible additional amount for common consumer goods such as food, produce, 

consumables and other commodities as a result of the proposed regulation. 

In considering the ability of fleets to handle the compliance requirements associated 

with the proposed regulation and other ARB regulations, staff believes this issue is 

addressed in that ARB’s various regulations have different compliance dates, regulatory 

requirements, and flexibility, which staggers the compliance dates and requirements for 

various regulations such that any overlap is typically minimal. Also, while many fleets 

subject to the proposed regulation are also subject to other ARB regulations, staff does 

not believe the cumulative cost impacts of these various regulations will impact affected 

fleets’ ability to comply overall. For example, for construction fleets subject to the 

proposed regulation, the cumulative impact of the proposed regulation and the In-Use 

Off-Road Diesel Vehicle Regulation is an additional 6 percent over the anticipated costs 

of the off-road regulation. 

While the cost of the proposed regulation is significant, there are also significant 

amounts of incentive money available for fleets to assist in cleaning up and modernizing 

their vehicles. In November 2006, California voters approved Proposition 1B, which 

included $1 billion to reduce emissions from the movement of goods throughout the 

state. ARB has earmarked over $300 million towards vehicles covered by the proposed 

regulation, and in particular vehicles operated by small fleets. California’s Carl Moyer 

Program provides $140 million per year to help reduce emissions from existing diesel 

engines, and has historically funded a significant number of projects targeting on-road 

vehicles. Finally, with the approval of Assembly Bill (AB) 118, ARB has been allocated 

up to $50 million per year to achieve emission reductions from vehicles and equipment, 

as well as research for on the air quality impacts of alternative fuels and advanced 

technology vehicles. In fiscal year 2008/2009, $48 million has been allocated for the 

establishment of a heavy-duty vehicle air quality loan program. While these programs, 

and the dollars they provide, are significant, they are not enough to cover the 

anticipated costs of the regulation. However, for those that take advantage of them, the 

combined assistance these programs could provide will be significant. For example, a 

truck owner/operator could obtain a 2010 model year engine truck, which would comply 

with all of the requirements of the proposed regulation, for about $500 to $800 per 

month in loan payments. 

Staff has made an enormous effort to notify affected fleets and interested parties about 

the proposed regulation, and to solicit their input on the regulation. Staff held 54 public 

workshops and workgroup meetings throughout the state, dozens of site visits and 

private meetings with fleet owners, vehicle dealers, and industry groups, and sent a 

mailing to nearly 300,000 owners of registered diesel vehicles in California notifying 
-7- 

them of the proposed regulation, how to participate in an online survey, and how to 

obtain additional information about staff’s proposal. 

C. Recommendation 

Staff recommends the Board adopt a new section 2025 in title 13, California Code of 

Regulations. In addition, staff recommends that the Board approve the proposed 

amendments to the existing regulations identified Chapter XI of this technical support 

document. The proposed regulation and the accompanying amendments to other 

existing regulations, are set forth in the proposed regulation order in Appendix A. 

D. References 

ARB, 2002. California Air Resources Board. California Air Resources Board Strategic 

Plan. January 2002. http://www.arb.ca.gov/planning/plan01/plan01.htm
-8- 
-9- 

II. REGULATORY AUTHORITY

ARB has been granted both general and specific authority under the Health and Safety 

Code (HSC) to adopt the proposed regulation. HSC sections 39600 (General Powers) 

and 39601 (Standards, Definitions, Rules and Measures) confer on ARB, the general 

authority and obligation to adopt rules and measures necessary to execute the Board’s 

powers and duties imposed by State law. HSC sections 43013 and 43018(a) provide 

broad authority to achieve the maximum feasible and cost-effective emission reductions 

from all mobile source categories, including both on-road and off-road diesel engines. 

Regarding in-use motor vehicles, HSC sections 43600 and 43701(b) respectively grant 

ARB authority to adopt emission standards and emission control equipment 

requirements. ARB is proposing amendments to the Portable Equipment Registration 

Program (PERP) pursuant to authority granted in HSC sections 41750-41755. 

Additionally, California's Air Toxics Program, established under California law by AB 

1807 (stats. 1983, ch. 1047, the Tanner Act) and set forth in the HSC sections 39650 

through 39675, mandates that ARB identify and control air toxics emissions in 

California. The identification phase of the Air Toxics Program requires ARB, with 

participation of other state agencies such as the Office of Environmental Health Hazard 

Assessment (OEHHA), to evaluate the health impacts of, and exposure to, substances 

and to identify those substances that pose the greatest health threat as toxic air 

contaminants (TACs). ARB's evaluation is then made available to the public and is 

formally reviewed by the Scientific Review Panel (SRP) established under HSC 

section 39670. Following the ARB's evaluation and the SRP's review, the Board may 

formally identify a TAC at a public hearing. Following the identification of a substance 

as a TAC, HSC section 39665 requires ARB, with the participation of the local air 

pollution control and air quality management districts (districts), and in consultation with 

affected sources and interested parties, to prepare a report on the need and appropriate 

degree of regulation for that substance. Based upon the findings of the report, ARB is 

vested with authority under sections 39666 and 39667 to adopt and enforce airborne 

toxic control measures (ATCM) that will respectively achieve emission reductions using 

best available control technology (BACT) for nonvehicular and vehicular sources, the 

latter of which includes in-use on-road heavy-duty vehicles. 

1. Preemption under the Clean Air Act 

The proposed regulatory actions would not be preempted by the federal Clean Air Act 

(CAA) section 209. Section 209(a) preempts states from adopting emission standards 

relating to the control of emissions from new motor vehicles or new motor vehicle 

engines. Section 209(b) provides that the Administrator of the United States 

Environmental Protection Agency (U.S. EPA) shall grant California a waiver of 

preemption, unless those challenging the waiver can show that certain specified criteria 

for denying the waiver have been met. Section 209(e)(1) preempts all states from 

adopting emission standards for new nonroad engines under 175 horsepower used in 

farm and construction equipment and vehicles and new locomotives and locomotive 
-10- 

engines.2 Section 209(e)(2) impliedly preempts all states other than California from 

adopting new and in-use emission standards and other requirements relating to the 

control of emissions of all nonroad not otherwise expressly preempted under section 

209(e)(1). California can adopt and enforce regulations for these other nonroad 

engines upon receiving authorization from the Administrator of U.S. EPA. As with a 

section 209(b) waiver, the Administrator must grant authorization unless those 

challenging the authorization can demonstrate that certain specified criteria for denying 

the authorization have been satisfied. 

The proposed in-use on-road diesel vehicle regulation would not be preempted under 

CAA section 209(a). The proposed regulation would not establish emission standards 

for new motor vehicles or engines; rather the proposed regulation would establish inuse performance requirements that must be met by in-use on-road vehicles. To the 

extent that fleets elect to meet those performance standards by replacing in-use 

vehicles and engines with new vehicles and engines, those emission standards have 

previously been adopted and granted waivers under section 209(b). 

The proposed amendments to ARB’s previously adopted heavy-duty vehicle idling 

requirements are also not preempted by section 209. The idling requirements are inuse operational control measures that are specifically permitted under section 209(d), 

which provides that states have the right “to control, regulate, or restrict the use, 

operation, or movement of registered or licensed motor vehicles.” The right to adopt inuse operational controls has been extended to nonroad engines. See Engine 

Manufacturers Association v. EPA, (D.C. Cir. 1996) 88 F.3d 1075. 

The proposed amendments to California’s off-road regulations are not preempted under 

section 209(e)(1) in that they do not apply to new off-road engines under 175 hp used in 

farm and construction vehicles or to new locomotives and locomotive engines. To the 

extent that ARB is proposing amendments to its in-use off-road programs, ARB has 

pending authorization requests before U.S. EPA for its previously adopted off-road 

regulations. Upon adoption of the proposed amendments, ARB intends to file a request 

with U.S. EPA that it confirm that the amendments fall within the scope of the previously 

submitted authorization requests. 

2. Interstate Commerce Clause 

The Commerce Clause of the United States Constitution (U.S. Const., Art. I, §8, cl. 3) 

grants Congress the power “[t]o regulate Commerce with foreign Nations, and among 

the several States. . . .” In addition to granting Congress an affirmative grant of 

authority, courts have found that the clause creates an implied restraint on state 

authority to enact legislation that imposes significant burdens on interstate commerce. 

(See United Haulers Ass'n, Inc. v. Oneida-Herkimer Solid Waste Management Authority 

(2007) 127 S.Ct. 1786; Healy v. The Beer Institute (1989) 491 U.S. 324, 326, fn.1.) 

The proposed regulation of in-use on-road diesel vehicles would not be in violation of 

 

2

 The federal term “nonroad” and California term “off-road” refer to the same types of engines 

and are used interchangeably. 
-11- 

this so-called Dormant Commerce Clause. The proposed regulation would not be per 

se unlawful in that it would not expressly discriminate against out-of-state heavy-duty 

vehicle fleets, have the practical effect or purpose of protecting California economic 

interests at the expense of out-of-state interests, or have an impermissible 

extraterritorial effect on other states. 

When a state statute or regulation is neutral on its face, has only indirect or incidental 

effects on interstate commerce, and regulates evenhandedly, the courts have applied a 

balancing test that weighs the state’s legitimate interests in adopting the regulation 

against the burden that the regulation may have on interstate commerce. (Pike v. Bruce 

Church, Inc. (1970) 397 U.S. 137.). Here, the proposed regulation, which achieves 

significant reductions in diesel PM, an identified TAC, and NOx, with concomitant 

reductions in health risks to the public (i.e., resulting in fewer fatalities, hospitalization, 

lost school and work days), would provide great health and welfare benefits to the 

public. The benefits of the regulation, which would be adopted under the police powers 

granted to the State, clearly outweigh any burdens that the regulation would impose on 

interstate commerce. 

3. Regulatory Takings 

Some stakeholders have commented during the course of this regulation’s development 

that the proposed regulation would result in a regulatory taking. Specifically, they argue 

that the proposed regulation forces the replacement of older, dirtier vehicles, and would 

significantly devalue the resale market for these vehicles. ARB staff does not agree that 

the regulation would result in an unconstitutional taking. The “Takings Clause” of the 

Fifth Amendment to the United States Constitution provides that the federal government 

shall not take private property for public use, without just compensation.3

 The 

prohibition was extended to the states by the Fourteenth Amendment.4 

Generally, in real property regulatory takings claims, courts have found a compensable 

taking if a regulation does not substantially advance legitimate state interests or has 

permanently deprived an owner of “all economically beneficial or productive use” of the 

land (Lucas v. South Carolina Coastal Council (1992) 505 U.S. 1003, 1015; TahoeSierra Preservation Council, Inc. v. Tahoe Regional Planning Agency (2002) 535 U.S. 

302). In determining whether a state may avoid compensation when it has used its 

police powers for public health and welfare purposes, and the action has resulted in 

 

3

 The Fifth Amendment provides in full: 

No person shall be held to answer for a capital, or otherwise infamous crime, unless on a 

presentment or indictment of a Grand Jury, except in cases arising in the land or naval 

forces, or in the Militia, when in actual service in time of War or public danger; nor shall any 

person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be 

compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, 

or property, without due process of law; nor shall private property be taken for public use, 

without just compensation. 

4

 The Fourteenth Amendment provides in relevant part that “[no State shall] deprive any person of life,

liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal 

protection of the laws.”
-12- 

depriving an owner of all beneficial or productive use of his land, the courts have looked 

to see if the proscriptions of the regulation were, in fact, covered by preexisting implied 

limitations on the property owner’s title. (Lucas v. South Carolina Coastal Council, 

supra, 505 U.S. at 1027.) In Lucas, the Court acknowledged that where such implied 

limitations exist, “the property owner necessarily expects the uses of his property to be 

restricted, from time to time, by various measures newly enacted by the State in 

legitimate exercise of its police powers.” (Id.) 

Of significance to the instant proposed regulation, the Court went on to clarify that 

implied limitations on ownership rights almost always exist with regard to the 

commercial value of personal property. The Court stated: 

[I]n the case of personal property, by reason of the State's traditionally high degree 

of control over commercial dealings, [the personal property owner] ought to be 

aware of the possibility that new regulation might even render his property 

economically worthless. (Id., at 1027-1028.) 

In line with the Supreme Court’s decisions with regulatory takings, the proposed 

regulation cannot be considered as unconstitutional. First, the regulation will not 

deprive the stakeholder of all beneficial value of the regulated engines and vehicles. 

Even those engines and vehicles that must be retired under the proposed regulation will 

continue to retain fair market value in domestic and international markets outside of 

California. Second, consistent with Lucas, even in the unlikely event the regulated 

engines and vehicles lost all of their beneficial value, ARB is exercising its vested police 

power authority to regulate in-use on-road fleets. Over the past 40 years, ARB has 

adopted a panoply of air quality regulations affecting nearly every vehicular source 

category. Given the extreme air quality problems confronting most areas of the state, 

owners of in-use on-road vehicles should be well aware that regulation of their fleets 

was likely to occur, especially given the high level of emissions associated with the 

operation of such vehicles. 
-13- 

III. PUBLIC OUTREACH AND ENVIRONMENTAL JUSTICE

ARB is committed to ensuring that all California communities have clean, healthful air by 

addressing not only the air quality issues confronting our cities by also the localized air 

quality impacts that are generated within our communities. ARB works to ensure that all 

individuals in California, especially the children and elderly, can live, work, and play in a 

healthful environment that is free from harmful exposure to air pollution. The proposed 

regulation's relationship to environmental justice is described in Section A below. 

Staff conducted various outreach efforts to notify affected stakeholders of the proposed 

regulation and to give them opportunities to participate in the regulatory development 

process. These efforts are described further below in Section B. 

A. Environmental Justice 

As a matter of policy, ARB is committed to integrating environmental justice in all of its 

activities. On December 13, 2001, the Board approved Environmental Justice Policies 

and Actions, which formally established a framework for incorporating environmental 

justice into the ARB's programs, consistent with the directives of State law. 

Environmental justice is defined as the fair treatment of people of all races, cultures, 

and incomes with respect to the development, adoption, implementation, and 

enforcement of environmental laws, regulations, and policies (ARB, 2001). These 

policies apply to all communities in California, but recognize that environmental justice 

issues have been raised more in the context of low-income and minority communities. 

As the proposed regulation would require cleaner fleets of in-use on-road diesel 

vehicles to be used throughout the state, it would reduce emissions in all communities 

in California, including those with environmental justice concerns. Staff are currently 

working to inform those in environmental justice communities of the proposed regulation 

and how final implementation would reduce exposure to diesel PM and protect public 

health in their communities. 

B. Outreach Efforts 

As part of the public process, staff conducted various outreach efforts to notify 

interested and affected stakeholders of the proposed regulation and to give them 

opportunities to participate in the regulatory development process. Staff held numerous 

public workshops at various locations throughout the state. Staff also met with 

individual stakeholders and contacted various industries, associations, individual 

businesses, and other organizations to inform them of the proposed regulation. A 

mailing to all owners of registered diesel vehicles in the State notifying them of staff’s 

proposal was conducted. Fact sheets were developed in English, Spanish and Punjabi 

to inform affected stakeholders of the proposed regulation, health impacts, and contact 

information. Additional information can be found in Appendix C. 

1. Public Workshops 

Since April 2006, staff held 9 sets of workshops, for a total of 54 public workshops, to 

discuss development of the proposed regulation. In August 2007, workshops were held 
-14- 

to specifically discuss updates to the emission inventory. In July 2008, workshops were 

specifically held to discuss methodologies for estimating costs and emissions attributed 

to the proposed regulation. The workshops were held in various locations throughout 

the State to allow stakeholders to participate in person. The workshops held in 

Sacramento were also webcast to provide even greater opportunity for stakeholder 

involvement. In many instances, staff held both day and evening workshops to allow 

stakeholders to attend at their convenience. 

Table III-1 shows the dates and locations of the workshops. The dates, locations, and 

times of the workshops are listed in Appendix C. 

Table III-1: Public Workshop Dates and Locations 

Dates Locations 

April 2006 Sacramento, El Monte, Fresno 

April 2007 Sacramento, El Monte 

July 2007 Sacramento, El Monte 

August 2007 Sacramento, El Monte, Fresno 

October 2007 Redding, San Diego, Sacramento, Fresno, El 

Monte, Oakland 

January - February 

2008 

Sacramento, Fresno, El Monte, Riverside, San 

Diego, El Centro, Redding, Berkeley 

May – June 2008 El Monte, San Diego, El Centro, Riverside, 

San Jose, Redding, Sacramento, Fresno 

July 2008 Fresno, El Monte, Sacramento 

July – August 2008 San Diego, El Centro, El Monte, Redding, San 

Jose, Sacramento, Riverside, Fresno, Arvin 

2. Other Outreach Efforts 

Due to the wide variety of industries that use on-road diesel-fueled vehicles and would 

be impacted by the proposed regulation, staff performed outreach to many different 

industries and associations. Table III-2 lists companies, associations, and organizations 

that were contacted by staff, notifying them of the proposed regulation. In addition, staff 

sent a mailing to nearly 300,000 owners of registered diesel vehicles in California 

notifying them of the proposed regulation, how to participate in an online survey, and 

how to obtain additional information about staff’s proposal (See Appendix C). 
-15- 

Table III-2: Companies, Associations, and other Organizations Contacted 

Allied Weed Control 

American Car and Bus Rental 

Association 

American Rental Association 

American Bus Association 

American Trucking Association 

The Better World Group 

Blackmun Equipment and Vehicle 

Leasing 

Blagg Food Services 

Boyd Commodities 

British Petroleum 

Bud Line Trucking 

California Bus Association 

California Cotton Ginners and Growers 

Association 

California Dump Truck Owners 

Association 

California Farm Bureau 

California Forestry Association 

California Highway Patrol 

California Independent Oil Marketers 

Association 

California School Transportation 

Association 

California Trucking Association 

California Tow Truck Association 

Calstart 

Cattlemen’s Association 

CCEEB 

Central Valley Air Quality Coalition 

Citrus Growers Association 

Coca Cola 

Construction Industry Air Quality 

Coalition 

Engine Manufacturers Association 

Environmental Defense Fund 

Federal Express 

Ganduglia Trucking 

Granite Construction 

Gibbs Truck Centers 

Holt 

International Logistics and Warehousing 

Foundation 

Interstate Truck Center 

ITEC 

Jim Seal Consulting Services 

Kajai Trucking 

Lawson Drayage 

Local Air Pollution Control Districts 

Mid-Pacific Industries 

Mountain Valley Express 

National Association of Fleet Managers 

Nisei Farmers League 

Northern American Power Sweepers 

Association 

Northern Refrigerated Transportation 

Owner-Operator Independent Drivers 

Association 

PACCAR 

Pacific Coast Companies 

Pacific Gas and Electric 

Pape’ Machinery 

Pat Cramer Insurance Agency 

Pepsi 

Port of Stockton 

Ritchie Brothers Auctioneers 

Roadrunner Manufacturing 

Save Mart 

SelectTrucks 

Sempra 

Sierra Research 

Storer Transportation 

Szeremi Sweeping Service 

Teamsters Union 

Union of Concerned Scientists 

United Motorcoach Association 

United Postal Service 

West Coast Collaborative 

Westar Transport 

Western Firefighters Association 

Western Propane Gas Association 

Western Trucking School 

Western United Dairymen Association 

Yellow Roadway Corporation 
-16- 

Staff also sent letters to diesel vehicle business owners in California (including truck 

stops and repair facilities throughout the Western United States) notifying them of the 

proposed regulation, and included a fact sheet so that they could notify their customers 

of the proposed regulation. Staff also provided ARB contact information (See Appendix 

C) so that additional information could be obtained. An existing toll free phone number, 

866-6DIESEL, was expanded to assist affected stakeholders in obtaining information 

about the proposed regulation and the survey by enabling them to directly contact staff 

working on the proposed regulation. 

Over the last two and a half years, staff held over 100 meetings with individual 

companies and organizations to discuss the proposed regulation. The meeting 

attendees ranged from just one company representative to over 100 attendees. This 

included over 50 meetings with individual companies to discuss how the proposed 

regulation will impact their businesses and to gather additional information about their 

business operations. The meetings also provided staff with additional information on 

how the proposed regulation will affect different types of companies that operate heavyduty diesel vehicles. Staff met at various locations throughout the state and also 

traveled to locations in other states, such as Florida, Arizona, Michigan, and Texas, to 

discuss the proposed regulation to fleet owners that travel through California. 

Staff also made presentations at several trucking, motorcoach, and heavy equipment 

shows. Listed in Appendix C are presentation appearances, the dates, names of 

companies or organizations, and locations where staff met with or made presentations 

about the proposed in-use on-road diesel vehicle regulation. 

C. Future Efforts 

If the proposed regulation is adopted, staff plans to continue and expand its outreach 

efforts to associations and other affected stakeholders. Staff would also look to 

expanding its existing toll free phone number, 866-6DIESEL, to assist stakeholders in 

obtaining information on how to comply with the regulation. During implementation, 

staff would work with affected stakeholders to educate them on complying with the 

requirements of the regulation in the least costly manner. This effort would include 

holding public workshops, seminars, and individual meetings throughout the State. 

Staff would also look to strengthen enforcement and compliance to ensure there is a 

level playing field in California. Also, staff plans to create a reporting system and tools 

to assist fleets in determining what compliance options are available and to develop 

their own compliance plans. Staff also plans to continue to work with industry 

representatives and associations on additional ways to educate different stakeholders. 

Staff would also build on the efforts already made to educate affected stakeholders 

about the in-use off-road regulation and would look to coordinate those efforts to ensure 

that owners of off-road and on-road equipment receive the information they would need 

about both regulations at the same time. Staff also plans to track the implementation of 

the In-Use Off-Road Diesel Vehicle Regulation and use that effort as a model for this 

regulation. This includes conducting training sessions throughout the state and 

developing guidance material and fact sheets for affected fleets. Staff also will 
-17- 

consider forming an advisory group representing fleets of all sizes and types, retrofit 

manufacturers and installers, consultants, engine manufacturers, and other affected 

industry groups. The overall mission of the advisory group would be to enhance 

outreach efforts, training and implementation materials for the regulation, and assist 

staff in being aware of needs of affected stakeholders and address specific issues. 

D. References 

ARB, 2001. California Air Resources Board, Policies and Actions for Environmental 

Justice Staff Report. December 13, 2001. 
-18- 
-19- 

IV. NEED FOR EMISSION REDUCTIONS

California’s mobile source emissions control programs have provided significant 

statewide reductions in emissions of carbon monoxide (CO), PM, sulfur oxides (SOx), 

and ozone precursors – NOx and volatile organic compounds (VOCs, also called 

reactive organic gases or ROG). However, even with the success of existing programs, 

over 90 percent of Californians still experience unhealthy levels of air pollution. Many 

areas in the State still exceed state and federal ambient air quality standards (AAQS); 

that is, they are non-attainment areas. Substantial new reductions in mobile source 

emissions are essential if the state is to attain and maintain the state and national 

AAQS. In addition, reducing diesel PM emissions from mobile sources is critical to 

reducing overall public exposure to ambient air toxic contaminants. 

A. Ozone and its Precursors 

Ground level ozone is the primary constituent of smog. Ozone is formed in the 

atmosphere as a result of reactions involving sunlight and two classes of precursors. 

One class of precursors includes nitric oxide and nitrogen dioxide, collectively referred 

to as NOx, and the other precursors or ROG. The highest levels of ozone are produced 

when both NOx and ROG emissions are present in significant quantities on clear 

summer days. Control measures that reduce the emissions of ozone precursors will 

also reduce the ambient concentration of ozone. 

1. Ambient Air Quality Standards for Ozone 

State and federal AAQS have been established for ozone, as shown in Table IV-1. 

Currently, there are two State standards for ozone: a one hour standard which has been 

in effect since 1987, and a new 8 hour standard that became effective May 17, 2006. 

This new 8 hour standard was based on the results of an evaluation of the adequacy of 

the 1987 standard, as required by the Children’s Environmental Health Protection Act 

(Senate Bill 25, Escutia, 1999). Senate Bill 25 (SB 25) directed the ARB, in consultation 

with the Office of Environmental Health Hazard Assessment (OEHHA), to “review all 

existing health-based ambient air quality standards to determine whether these 

standards protect public health, including infants and children, with an adequate margin 

of safety. 

In July 1997, U.S. EPA promulgated a new 8 hour ozone national standard (replacing 

the previous federal one hour standard) effective September 1997, and in 2004 issued 

new area designation maps for the new standard. The new standard was set at a lower 

level to address the cumulative impact of ozone exposure at lower levels for a longer 

period of time and is more protective of human health. The national one hour ozone 

standard was revoked effective June 15, 2005, for all areas except the 8 hour ozone 

non-attainment Early Action Compact areas that have deferred effective dates for their 

designations under the 8 hour ozone standard. 
-20- 

Table IV-1: State and National Ozone Ambient Air Quality Standards5

Averaging Time California Standard National Standard 

1 hour 0.09 ppm (180 μg/m3) --6

8 hour 0.070 ppm (137 μg/m3) 0.08 ppm (157 μg/m3) 

Because the new 8 hour State standard is more health protective than the one hour 

standard, it tends to determine the ozone area designations. As a result, a large 

number of areas that were formerly designated as attainment, unclassified, or 

transitional-attainment for ozone based on the one hour standard are now classified as 

nonattainment based on the 8 hour standard (ARB, 2006a). 

In November 2006, the Board approved needed changes to the State area designations 

based on the new 8 hour ozone standard. As shown in Figure IV-1, most of California 

does not meet the State’s AAQS for ozone. The Lake County Air Basin and in the North 

Coast Air Basin: Del Norte, Humboldt, Trinity, and Mendocino counties continue to be in 

attainment, but Sonoma County has changed from attainment to nonattainment. 

Figure IV-1 also shows that many areas in the state violate the federal 8 hour ozone 

standard. U.S. EPA has designated 15 areas in California as nonattainment for the 

federal 8 hour ozone standard. These areas include San Joaquin Valley, South Coast 

Air Basin, Sacramento region, San Diego, Ventura, the San Francisco Bay Area, and a 

number of air districts downwind of urban areas. Federal law mandates development of 

SIPs documenting the actions the state will take to attain the standard. 

Substantial new ozone precursor emission reductions are needed not only to achieve 

attainment for the 8 hour state and federal ozone standards, but also to meet progress 

requirements for the ozone standard required under California law. The greatest 

emissions reductions are needed in the South Coast and San Joaquin Valley Air 

Basins. Both the South Coast and San Joaquin Valley air districts have requested 

reclassification to “extreme” nonattainment for ozone, with an attainment date in 2024. 

 

5

 ppm= parts per million, μg/m3=micrograms per cubic meter 

6

 The U.S. EPA revoked the national 1 hour ozone standard (0.120 ppm) effective 

June 15, 2005. 
-21- 

Figure IV-1: Federal and State Area Designations for Ozone 

2. Ambient Air Quality Standards for Nitrogen Dioxide (NO2) 

The primary sources of nitrogen dioxide (NO2) are internal combustion engines, both 

gasoline and diesel powered, and point sources such as power plants. NO2 is also 

formed indirectly from emissions of nitric oxide (NO) that are converted photochemically 

to NO2. Both NO and NO2 are involved in a series of chemical reactions in the ambient 

air to produce additional pollutants such as ozone, nitric acid, nitrate aerosols, and other 

nitrogen containing compounds that are toxic. Of the nitrogen oxide compounds (NOx) 

in the atmosphere, NO2 represents the greatest risk to human health (Frampton, 2000). 

The U.S. EPA has established a national AAQS for NO2 of 0.053 parts per million (ppm) 

averaged over one year. The ARB established a short term (one hour) standard for 

NO2 of 0.25 ppm, averaged over one hour. As required by SB 25, staff of ARB and 

OEHHA reviewed the scientific basis for California’s ambient standard for NO2 to 

determine its adequacy to protect public health, including the health of infants and 

children. Staff found that health effects may occur at levels near the existing standard 

of 0.25 ppm, and recommended that the level of the California ambient air quality 

standard for NO2 be lowered to 0.18 ppm, averaged over one hour. OEHHA staff also 

recommended the addition of an annual average standard of 0.03 ppm (ARB, OEHHA, 

2007). 

Though the state and federal NO2 standards are not exceeded, NO2 is still a concern 

because it is a precursor to both ozone and particulate matter. Secondary ammonium 

nitrate is formed from the oxidation NOx to nitric acid followed by the reaction of nitric 

acid with gaseous ammonia. The oxidation of NOx to nitric acid can occur during the 

daytime through reactions involving the hydroxyl (-OH) radical and during the nighttime 
-22- 

through reactions with ozone and water. Secondary ammonium nitrate is a significant 

component of particulate emissions in the South Coast. Therefore, reducing ammonium 

nitrate through controls on NOx sources is a critical part of the State’s PM strategy. 

3. Health Effects of Ozone 

Ozone is a powerful oxidant that can have substantial health impacts even at very low 

levels. Scientific studies show that exposure to ozone can result in reduced lung 

function, increased respiratory symptoms, increased airway hyperreactivity, and 

increased airway inflammation. Exposure to ozone is also associated with premature 

death, hospitalization for cardiopulmonary causes, emergency room visits for asthma, 

and restrictions in activity (ARB, 2005a). 

Short term exposure to high ambient ozone concentrations have been linked to 

increased hospital admissions and emergency visits for respiratory problems (U.S. EPA, 

2000). Repeated exposure to ozone can make people more susceptible to respiratory 

infection and lung inflammation and can aggravate pre-existing respiratory diseases, 

such as asthma. Prolonged (6 to 8 hours), repeated exposure to ozone can cause 

inflammation of the lung, impairment of lung defense mechanisms, and possibly 

irreversible changes in lung structure, which over time could lead to premature aging of 

the lungs and/or chronic respiratory illnesses such as emphysema and chronic 

bronchitis. 

Those most susceptible to ozone health effects include individuals exercising outdoors, 

children and people with pre-existing lung disease such as asthma, and chronic 

pulmonary lung disease. Children are more at risk from ozone exposure because they 

typically are active outside during the summer when ozone levels are highest. Also, 

children are more at risk than adults because their respiratory systems are still 

developing. Adults who are outdoors and moderately active during the summer months, 

such as construction workers and other outdoor workers, also are among those most at 

risk. These individuals, as well as people with respiratory illnesses such as asthma, 

especially asthmatic children, can experience reduced lung function and increased 

respiratory symptoms, such as chest pain and cough, when exposed to relatively low 

ozone levels during prolonged periods of moderate exertion. 

Reducing emissions of ozone precursors would reduce the prevalence of the types of 

respiratory problems associated with ozone exposure and would reduce hospital 

admissions and emergency visits for respiratory problems. 

B. Particulate Matter 

Ambient PM is a complex mixture of very small particles and liquid droplets in the air. 

Ambient PM is comprised of directly emitted PM such as dust and soot, known as 

primary PM, as well as secondary PM formed in the atmosphere from the reactions of 

precursor gases, such as NOx, SOx, VOCs, and ammonia (ARB, 2005b). NOx, SOx, 

and ammonia combine to form secondary ammonium nitrate and sulfate. Volatile 

organic compounds (VOCs) can form secondary organic aerosols as well as participate 
-23- 

in the production of secondary ammonium nitrate. Particles with diameter less than or 

equal to 10 microns are referred to as PM10 and particles up to 2.5 microns in diameter 

are referred to as PM2.5. Those particles with diameter between 2.5 and 10 microns 

are referred to as coarse particles while PM2.5 are described as fine particles. PM2.5 is 

therefore a subset of PM10. In general, combustion processes form fine particles, while 

emissions from dust sources tend to be predominantly coarse particles. 

The health and environmental effects of PM are related to the size of the particles. Fine 

particles can remain in the atmosphere for days to weeks and travel through the 

atmosphere for hundreds to thousands of kilometers, while coarse particles deposit to 

the earth within minutes to hours and within 10 kilometers from the emission source. 

Particles in the PM2.5 size range can penetrate into the deepest regions of the lungs. 

1. Ambient Air Quality Standards for PM 

ARB and the U.S. EPA have adopted health based ambient air quality standards for 

PM10 and PM2.5. In September 2006, the U.S. EPA lowered the short term ambient air 

quality standard for PM2.5 from 65 μg/m3

to 35 μg/m3 and revoked the annual standard 

for PM10. The annual average state standard for PM10 was lowered in 2002 from 

30 ug/m3

 to the current standard of 20 ug/m3 after an evaluation by ARB and OEHHA 

staff of the literature on health effects associated with PM at or below 30 ug/m3

. 

Table IV-2 shows the current federal and state standards. California’s ambient air 

quality standards for PM are more stringent than the national standards and, like the 

ozone standards, are intended to provide protection for the most sensitive groups of 

citizens, including infants and children, the elderly, and persons with heart or lung 

disease. 

Table IV-2: State and National PM Ambient Air Quality Standards (μg/m3) 

Standard California National 

Annual Arithmetic Mean 20 --7 

PM10 24 Hour Average 50 150 

Annual Arithmetic Mean 12 15 PM2.5 24 Hour Average --8

 35 

Most of California is designated as non-attainment for the State PM10 standard. 

Currently, the only areas that attain the State PM10 standard are the Lake County Air 

Basin and Siskiyou County in the Northeast Plateau Air Basin. The portion of Sonoma 

County in the North Coast Air Basin has been recommended for redesignation as 

attainment for PM10 (ARB, 2006a). With respect to the national 24 hour PM10 

standard, the San Joaquin Valley, the South Coast and several desert air basins are in 

non-attainment. As shown in Figure IV-2, most urban areas and several isolated sub-

 

7 The U.S. EPA recently rescinded the annual PM10 standard of 50 μg/m3. 

8 No separate State standard. 
-24- 

areas are in nonattainment for the State PM2.5 standard. However, the only federal 

nonattainment areas for the national annual average PM2.5 standard are the San 

Joaquin Valley and the South Coast. 

Figure IV-2: Federal and State Area Designations for PM2.5 

Because of the State’s nonattainment status, PM emissions reduction remains one of 

California’s highest public health priorities. The nonattainment areas with serious 

problems will require substantial reductions of directly emitted PM2.5 pollutants and 

PM2.5 precursors. Based on atmospheric modeling performed by ARB staff, control of 

the emissions of ozone precursors (and in particular NOx) may provide significant 

benefit due to the reduction in ambient concentrations of nitrate – an important 

component of ambient PM2.5. 

2. Health Effects of Particulate Matter 

There are strong and consistent associations between daily exposure to PM (measured 

as PM10, PM10-PM2.5, or PM2.5) and a range of adverse health outcomes. These 

include premature mortality, aggravation of respiratory and cardiovascular disease (as 

indicated by increased hospital admissions and emergency room visits, school 

absences, work loss days, and restricted activity days), asthma exacerbation, chronic 

and acute bronchitis, and reductions in lung function. The more severe outcomes are 

experienced primarily by the elderly and people with pre-existing chronic heart and lung 

disease. Children under age five may also experience serious adverse outcomes from 

exposure to PM10, including premature mortality and hospitalization for respiratory 

conditions (ARB, OEHHA 2002). 

Almost all of diesel PM is in the PM2.5 fraction. Because of its significance also as a 

toxic air contaminant, diesel PM is discussed separately later in this chapter. 
-25- 

C. Toxic Air Contaminants 

1. Components of Diesel Exhaust 

Diesel engines emit a complex mixture of inorganic and organic compounds that exist in 

gaseous, liquid, and solid phases. The composition of this mixture will vary depending 

on engine type, engine age and horsepower, operating conditions, fuel, lubricating oil, 

and whether or not an emission control system is present. The primary gas or vapor 

phase components of diesel exhaust include typical combustion gases and vapors such 

as CO, carbon dioxide, sulfur dioxide, NOx, ROG, water, and excess air (nitrogen and 

oxygen). 

Diesel exhaust contains over 40 substances (shown in Table IV-3) that have been listed 

as TACs by the state of California and as hazardous air pollutants by U.S. EPA. Fifteen 

of these substances are listed by the International Agency for Research on Cancer 

(IARC) as carcinogenic to humans, or as a probable or possible human carcinogen 

(ARB, 1998). U.S. EPA also classified diesel exhaust as likely to be carcinogenic to 

humans by inhalation at environmental exposures (U.S. EPA, 2002). 

Table IV-3: Substances in Diesel Exhaust Listed by California as Toxic Air 

Contaminants 

Acetaldehyde Formaldehyde 

Acrolein Inorganic lead 

Aniline Manganese compounds 

Antimony compounds Mercury compounds 

Arsenic Methanol 

Benzene Methyl Ethyl Ketone 

Beryllium compounds Naphthalene 

Biphenyl Nickel 

Bis[2-ethylhexyl]phthalate 4-Nitrobiphenyl 

1,3-Butadiene Phenol 

Cadmium Phosphorus 

Chlorine Polycyclic organic matter, including polycyclic 

aromatic hydrocarbons (PAHs) and their derivatives 

Chlorobenzene Propionaldehyde 

Chromium compounds Selenium compounds 

Cobalt compounds Styrene 

Creosol isomers Toluene 

Cyanide compounds Xylene isomers and mixtures 

Dibutylphthalate o-Xylenes 

Dioxins and dibenzofurans m-Xylenes 

Ethyl benzene p-Xylenes 

2. Diesel Particulate Matter 

Diesel PM is either directly emitted from diesel powered engines (primary particulate 

matter) or is formed from the gaseous compounds emitted by a diesel engine 

(secondary particulate matter). Diesel PM consists of both solid and liquid material and 
-26- 

can be divided into three primary constituents: the elemental carbon fraction (ECF); the 

soluble organic fraction (SOF), and the sulfate fraction. 

Many of the diesel particles exist in the atmosphere as a carbon core with a coating of 

organic carbon compounds, or as sulfuric acid and ash, sulfuric acid aerosols, or sulfate 

particles associated with organic carbon (Kittelson et al., 1999). Diesel PM can be 

distinguished from noncombustion sources of PM2.5 by the high content of elemental 

carbon and the high number of ultrafine particles (organic carbon and sulfate). 

The SOF consists of unburned organic compounds which condense into liquid droplets 

or are adsorbed onto the surfaces of the elemental carbon particles. Several 

components of the SOF have been identified as individual TACs. The organic fraction 

of the diesel particle contains compounds such as aldehydes, alkanes and alkenes, and 

high-molecular weight polycyclic aromatic hydrocarbons (PAH) and PAH-derivatives. 

Many of these PAHs and PAH derivatives, especially nitro-PAHs, have been found to 

be potent mutagens and carcinogens. Nitro-PAH compounds can also be formed 

during transport through the atmosphere by reactions of adsorbed PAH with nitric acid 

and by gas phase radical initiated reactions in the presence of NOx. Atmospheric 

reactions of these gas phase PAH and nitro-PAH derivatives may lead to the formation 

of several mutagenic nitro-PAH, and nitro-PAH compounds, including 

nitrodibenzopyranones, 2 nitroflouranthene and 2 nitropyrene (Arey et al., 1988). 

Almost all of the diesel particle mass is in the PM10 fraction, and approximately 

94 percent of the mass of these particles is less than 2.5 microns in diameter (PM2.5). 

The particles have a very large surface area per unit mass which makes them excellent 

carriers for many of the organic compounds and metals found in diesel exhaust. 

Because of their small size, the particles are readily respirable and can effectively reach 

the lowest airways of the lung along with the adsorbed compounds, many of which are 

known or suspected mutagens and carcinogens (ARB, 1998). 

Diesel PM was identified by the Board as a TAC in 1998 after an extensive review and 

evaluation of the scientific literature by OEHHA and subsequent review by the Scientific 

Research Panel (SRP). In 2001, the U.S. EPA identified diesel PM and diesel exhaust 

organic gases as a Mobile Source Air Toxic (MSAT) (U.S. EPA, 2001). 

D. Health Impacts of Exposure to Diesel Exhaust and Diesel PM 

Diesel PM, with the associated organic compounds, plays a key role in the 

carcinogenicity and chronic noncancer effects of exposure to diesel exhaust. The 

findings from more than 30 human epidemiological studies indicate that on average, 

long term occupational exposures to diesel exhaust were associated with a 40 percent 

increase in the relative risk of lung cancer (OEHHA, 1998). However, there is limited 

specific information that addresses the variable susceptibilities to the carcinogenicity of 

diesel exhaust within the general human population and vulnerable subgroups, such as 

infants and children and people with pre-existing health conditions. The carcinogenic 

potential of diesel exhaust was also demonstrated in numerous genotoxic and 
-27- 

mutagenic studies on some of the organic compounds typically detected in diesel 

exhaust (OEHHA, 1998). 

Health impacts from exposure to the PM2.5 component of diesel exhaust have been 

calculated for California, using concentration-response equations from several 

epidemiologic studies. Both mortality and morbidity effects could be associated with 

exposure to either direct diesel PM2.5 or indirect diesel PM2.5, the latter of which arises 

from the conversion of diesel NOx emissions to PM2.5 nitrates. It was estimated that 

2000 and 900 premature deaths resulted from long term exposure to either 1.8 μg/m3

 of 

direct PM2.5 or 0.81 μg/m3 of indirect PM2.5, respectively, for the year 2000 (Lloyd and 

Cackette, 2001). The mortality estimates are likely to exclude cancer cases, but may 

include some premature deaths due to cancer, because the epidemiologic studies did 

not identify the cause of death. Exposure to fine particulate matter, including diesel 

PM2.5, can also be linked to a number of heart and lung diseases. Another highly 

significant health effect of diesel exhaust exposure is its apparent ability to act as an 

adjuvant in allergic responses and possibly asthma (Diaz-Sanchez et al., 1996, 1999, 

Takano et al., 1998). However, additional research is needed at diesel exhaust 

concentrations that more closely approximate current ambient levels before the role of 

diesel exhaust exposure in the increasing allergy and asthma rates is established. 

Diesel PM is a major contributor to potential ambient risk levels. Using the cancer unit 

risk factor developed by OEHHA for the TAC program, it was estimated that for the year 

2000, exposure to ambient concentrations of diesel (1.8 μg/m3) could be associated 

with a health risk of 540 potential cancer cases per million people exposed over a 

70 year lifetime. This diesel PM cancer risk accounted for approximately 70 percent of 

the total risk associated with all known ambient air toxics as shown in Figure IV-3. 
-28- 

Figure IV-3: State Average Potential Cancer Risk from Outdoor Ambient Levels of 

Toxic Pollutants for the Year 20009,10,11

The South Coast Air Quality Management District (SCAQMD) Multiple Air Toxics 

Exposure Study II (MATES II) estimated that the average potential cancer risk in the 

South Coast Air Basin from diesel PM was about 1,000 excess cancers per million 

people, or 71 percent of the average cancer risk from all air toxics in the South Coast 

Air Basin. For localized or near source exposures to diesel exhaust, such as might 

occur near busy roads and intersections, the potential risks will be much higher. 

The Multiple Air Toxics Exposure Study III (MATES III) has been completed and is a 

follow up to previous air toxics studies in the Basin. The scope of the monitoring was 

from April 2004 to March 2006. The SCAQMD held a public consultation meeting on 

August 26, 2008, to discuss the revised draft of the MATES III report. The final report 

has not been posted, but the Draft Final Report (July, 2008) is available at: 

http://www.aqmd.gov/prdas/matesIII/MATESIIDraftFinalReportJuly2008.html. 

1. Health Impacts of Exposure to Diesel PM from On-Road Diesel Vehicles 

A substantial number of epidemiologic studies have found a strong association between 

exposure to ambient PM and adverse health effects (ARB, OEHHA, 2002). Staff 

quantified seven non-cancer health impacts associated with diesel PM emissions from 

 

9 ARB, 2000.

10 Diesel exhaust PM10 potential cancer risk based on 2000 emission inventory estimates. All 

other potential cancer risks based on air toxics network data. Used 1997 data for paradichlorobenzene. Used 1998 monitoring data for all others. Assumes measured 

concentrations are equivalent to annual average concentrations and duration of exposure is 

70 years, inhalation pathway only.

11

 Includes carbon tetrachloride (4 percent), formaldehyde (2.5 percent), hexavalent chromium 

(2.2 percent), para-dichlorobenzene (1.2 percent), acetaldehyde (0.7 percent), 

perchloroethylene (0.7 percent), and methylene chloride (0.3 percent).

Diesel Exhaust PM10

71%

1,3-Butadiene

10%

Benzene

8%

Other Toxics

11%
-29- 

on-road diesel engines in California in 2008. The non-cancer health effects include 

premature death, asthma attacks, acute bronchitis, hospital admissions, work loss days, 

and minor restricted activity days. Staff also quantified the non-cancer health impacts 

associated with exposures to diesel PM resulting from on-road diesel vehicle activities 

in an urban study area in Southern California. 

a) Statewide Non-Cancer Health Impacts 

The health outcomes take into account a number of factors including the relationship 

between air pollutant concentrations and the effect found in health studies, the relative 

contribution of emission sources to the pollutant in a region, and the population in a 

region. The regional impacts, by air basin, were added together to provide a statewide 

total. Appendix D provides a description of the methodology used to quantify the health 

impacts reported in this section. 

Staff estimates that in the year 2008, approximately 4,500 premature deaths can be 

associated with the estimated baseline emissions from in-use on-road diesel vehicles 

subject to the proposed regulation. Table IV-4 shows the range of cases statewide in 

2008 for each health impact evaluated by staff. As shown, staff estimates that there 

would be about 1,210 hospital admissions due to respiratory and cardiovascular 

causes; 71,000 cases of asthma-related and other lower respiratory symptoms; 

450,000 days of work loss; and 2,600,000 minor restricted activity days. The analysis 

included health impacts of direct diesel PM and indirect diesel PM – nitrates formed 

from precursor NOx emitted by on-road diesel engines. The impacts of direct and 

indirect sources of PM are listed separately in Table IV-4. The health impacts of NOx 

as a precursor to ozone are not included in the estimates. Because only a subset of 

health outcomes was considered, the estimates in Table IV-4 should be considered an 

underestimate of the total public health impact of diesel PM exposure. Appendix D 

provides a description of the methodology used to generate these estimates. 

The statewide health impacts from in-use on-road diesel vehicles are significant. To put 

the magnitude of the impact of on-road diesel vehicles covered by the proposed 

regulation in context, the number of premature deaths estimated for 2008 is similar to 

the number of deaths due to environmental tobacco smoke (secondhand smoke) and to 

the number of deaths due to motor vehicle accidents. Secondhand smoke is estimated 

to cause about 4,000 premature deaths per year in California (ARB, 2006b), while motor 

vehicle accidents killed 4,236 people in California in 2006 (NCSA, 2007). 
-30- 

Table IV-4: Statewide Health Impacts Associated with In-Use On-Road Diesel 

Vehicles (Baseline Year 2008) 

Endpoint Pollutant Number of Cases 

(Mean) Range (95% C.I.) 

PM 1,100 330 – 2,000 

Premature Mortality NOx 3,400 1,000 – 6,000 

Total 4,500 1,400 – 8,000 

PM 21 8 – 35 

NOx 560 320 – 830 Hospital admissions 

(Respiratory) Total 590 330 – 865 

PM 90 47 – 130 

NOx 530 330 – 780 Hospital admissions 

(Cardiovascular) Total 620 380 – 910 

PM 18,000 6,900 – 28,000 

NOx 53,000 21,000 – 83,000 Asthma & Lower 

Respiratory Symptoms Total 71,000 28,000 – 111,000 

PM 1,500 0 – 3,200 

Acute Bronchitis NOx 4,200 0 – 8,700 

Total 5,700 0 – 12,000 

PM 110,000 93,000 – 130,000 

Work Loss Days NOx 340,000 290,000 – 390,000 

Total 450,000 380,000 – 520,000 

PM 640,000 520,000 – 760,000 

NOx 2,000,000 1,600,000 – 2,300,000 Minor Restricted 

Activity Days Total 2,600,000 2,100,000 – 3,100,000 

b) Localize Non-Cancer Health Impacts from In-Use On-Road Diesel 

Vehicles 

To evaluate the health impacts from in-use on-road heavy-duty diesel vehicles at a local 

level, staff performed a localized urban study in and around the city of Commerce 

(Commerce Study). This study area was a 10 mile by 10 mile region with Commerce as 

its center. 

This study area was selected due to the large number of freeways and major arterials in 

the area which historically have had high volumes of on-road diesel vehicle traffic. This 

area contains a broad mix of land uses including industrial; light industrial; commercial; 

and residential and about 1.1 million people reside in the study area. The expected 

concentrations for the vehicle activity are high enough and there is a sufficiently large 

exposed population to allow quantification of the non-cancer health impacts of direct 

diesel PM in the urban study area. 

Vehicle speed, vehicle miles traveled (VMT), and emission factors were used to 

estimate emissions from in-use on-road diesel vehicles. Dispersion modeling was used 
-31- 

to estimate the ambient concentration of diesel PM resulting from in-use on-road diesel 

vehicles travelling on the freeways and local streets within the modeling domain. For 

this study, ARB staff selected the U.S. EPA’s approved air dispersion model AERMOD 

to estimate the impacts associated with diesel PM emissions on major freeways, as well 

as major and minor arterials within the domain. AERMOD has been successfully used 

in many applications including several recent health risk assessments of rail yards 

located in California. A detailed description of the model domain, source 

characterization, and meteorological data used are listed in Appendix E. 

As shown in Table IV-5 below, staff estimates that in 2003, approximately 42 premature 

deaths were associated with exposure to the baseline uncontrolled emissions of directly 

emitted diesel PM from in-use on-road diesel vehicles operating in the study area. 

Table IV-5 shows the range of cases for this area in 2003, for each health impact 

evaluated by staff. As shown, staff estimates that there would be about 32 hospital 

admissions due to respiratory and cardiovascular causes; 1,400 cases of asthmarelated and other lower respiratory symptoms; 7,400 days of work loss; and 

43,000 minor restricted activity days. The health impacts of indirect PM (nitrates formed 

from precursor NOx emissions) and NOx as a precursor to ozone are not included in the 

estimates. Because only a subset of health outcomes was considered, the estimates in 

Table IV-5 should be considered an underestimate of the total public health impact in 

this area from diesel PM exposure. 

Table IV-5: Non-Cancer Health Impacts Associated with In-Use On-Road Diesel 

Vehicles Operating in the Southern California Study Area (2003 Emissions) 

Endpoint 

Number of Cases 

per Year 

(Mean) 

Number of Cases per Year 

(Range: 95% Confidence 

Interval) 

Premature Mortality 42 12 – 72 

Hospital admissions 

(Respiratory and 

Cardiovascular) 

32 13 – 50 

Asthma – Related & 

Lower Respiratory 

Symptoms 

1,400 540 – 2,200 

Acute Bronchitis 120 0 – 260 

Work Loss Days 7,400 6,200 – 8,900 

Minor Restricted 

Activity Days 43,000 36,000 – 50,000 

c) Localize Potential Cancer Risk from Exposure to Diesel PM 

Emissions from On-Road Diesel Vehicles 

As part of the Commerce Study, staff estimated the localized potential cancer risk in 

2003 from exposure in this community to ambient levels of directly emitted diesel PM 

emitted from on-road diesel vehicles that would be subject to the proposed regulation. 

The results from this analysis provide a quantitative estimate for this community, as well 
-32- 

as a qualitative indicator for other similar urban areas. The Commerce study area was 

selected so staff could use transportation data provided from the Southern California 

Association of Government (SCAG). 

The potential cancer risks were estimated using standard risk assessment procedures 

based on the annual average concentration of diesel PM predicted by the model and a 

health risk factor (referred to as a cancer potency factor) that correlates cancer risk to 

the amount of diesel PM in the air. The methodology used to estimate the potential 

cancer risks assumes that an individual is exposed to an annual average concentration 

of a pollutant continuously for 70 years.12 The potential cancer risk is expressed as 

chances per million people. Appendix E provides the details of the scenarios and the 

methodology used to determine the risk. 

A cancer risk of 10 in a million is the most commonly used threshold above which 

facilities are required by the Air Toxics Hot Spots Information and Assessment Act to 

notify all exposed persons (ARB, 2005c). By comparison, an estimated cancer risk of 

500 per million occurs at approximately 500 to 5,000 feet from the edges of the major 

freeways. At about a quarter to several miles from the edges of the major freeways, the 

estimated cancer risks drop to about 200 in a million. 

The overall average potential cancer risk within the study area is about 375 in a million. 

This represents a significant portion of the overall estimated regional potential risk level 

in the South Coast Air Basin, which was estimated to be about 900 to 1000 in a million 

for all diesel PM emissions in 2000 (SCAQMD 2000). 

E. Diesel PM Risk Reduction 

To begin to address the adverse health impacts for diesel PM, in 1998, the Board 

identified diesel PM as a toxic air contaminant and in 2000 adopted the Risk Reduction 

Plan to Reduce Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles 

(Diesel Risk Reduction Plan or RRP) (ARB, 2000). The Plan identified Airborne Toxic 

Control Measures (ATCMs) and regulations that would set more stringent exhaust 

emission standards for new diesel-fueled engines and vehicles, establish retrofit 

requirements to reduce emissions from existing engines, vehicles, and equipment, and 

require the sulfur content of diesel fuel to be reduced to no more than 15 parts per 

million by weight (ppmw). The new sulfur standard was needed to enable the effective 

performance of the emission control technologies. The goal of the RRP was to reduce 

the risk of exposure to diesel PM by 75 percent by 2010, and by 85 percent by 2020, 

from the 2000 baseline. The scope of the RRP was broad, addressing all categories of 

engines, both mobile and stationary, and included control measures for private and 

public fleets of on-road and off-road diesel vehicles. 

 

12According to the OEHHA Guidelines, the relatively health-protective assumptions incorporated 

into the Tier 1 risk assessment make it unlikely that the risks are underestimated for the 

general population. 
-33- 

Since 2000, the Board has adopted a series of regulations to reduce risk from diesel 

particulate matter emissions. The regulations listed below have either been structured 

to require that each engine be equipped with the best available control technology 

(BACT) to reduce diesel PM emissions or require that fleets meet increasingly stringent 

fleet average emission rates. 

• Solid waste collection vehicles (ARB, 2003a); 

• Transit buses (ARB, 2005d); 

• Transit fleet vehicles (ARB, 2005e); 

• On-road public fleets and utility fleets (ARB, 2005f); 

• Cargo handling equipment at ports and intermodal rail yards (ARB, 2005g); 

• Stationary diesel engines (ARB, 2003b); 

• Portable equipment (ARB, 2004); 

• Ship auxiliary engines (ARB, 2005h); 

• Transport refrigeration units (ARB, 2003c); 

• School bus idling (ARB, 2002); 

• Commercial vehicle idling (ARB, 2005i); 

• In-use off-road diesel vehicles (ARB, 2007a); 

• Commercial harborcraft (ARB, 2007b); 

• Drayage trucks (ARB, 2007c); 

Diesel engines have long useful lives with the capability of being rebuilt several times. 

Retrofit programs and the accelerated replacement of older engines with newer cleaner 

engines must play an important role in achieving the ARB’s near term and long term air 

quality goals. The proposed regulation incorporates elements of both approaches to 

cleaning up the in-use on-road diesel fleet. 

F. State Implementation Plan Commitments 

In addition to playing a significant role in contributing to adverse health impacts to 

California’s, diesel engines, and in particular on-road vehicles, are a significant 

contributor to poor air quality throughout the state. Fifteen areas in California are 

designated nonattainment of the federal ozone standard, including South Coast Air 

Basin, San Joaquin Valley, Sacramento region, San Diego, Ventura, and a number of 

air districts downwind of urban areas. In addition, the South Coast Air Basin and the 

San Joaquin Valley are designated nonattainment of the federal PM2.5 standard. 

Federal law mandates the development of SIPs documenting the actions the state will 

take to attain the federal air quality standards in these areas. 

In September 2007, ARB adopted a SIP committing the State to develop measures to 

achieve emission reductions from sources under State regulatory authority. While 

multiple areas across the State exceed federal air quality standards, air quality in the 

South Coast and the San Joaquin Valley poses the greatest challenge and defines the 
-34- 

amount of reductions needed. Reductions are needed by 2014 to meet the PM2.5 

attainment deadline and by 2023 to meet the ozone attainment deadline. An interim 

target date of 2017 was adopted by ARB for the San Joaquin Valley as part of an effort 

to accelerate progress toward ozone attainment before 2023. 

The largest share of new emission reductions in the 2007 SIP is expected from in-use 

on-road diesel vehicles. In 2014, reductions from both NOx and PM2.5 are needed to 

meet the PM2.5 standard. In 2023 and 2017, the focus from an ozone air quality 

standard attainment perspective is NOx. Therefore, ARB adopted 2014 reduction 

commitments for both NOx and PM2.5, and NOx commitments in 2017, 2020 and 2023. 

As part of the overall SIP commitment, ARB staff is also obligated to bring measures to 

the Board for its consideration. Board consideration of this proposed is one of these 

commitments. ARB staff has used the targeted reductions estimated in the SIP as the 

goal for this rulemaking. 

G. References 

ARB, 1998. California Air Resources Board. Report to the Air Resources Board on the 

Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant. Appendix III, 

Part A. Exposure Assessment. As Approved by the Scientific Review Panel on 

April 22, 1998. http://www.arb.ca.gov/toxics/id/summary/diesel_a.pdf

ARB, 2000. California Air Resources Board. Risk Reduction Plan to Reduce Particulate 

Matter Emissions from Diesel-Fueled Engines and Vehicles. October 2000, p. 15 

http://www.arb.ca.gov/diesel/documents/rrpapp.htm

ARB, 2002. California Air Resources Board. Staff Report: Airborne Toxic Control 

Measure to Limit School Bus Idling and Idling at Schools. October 2002. 

ARB, 2003a. California Air Resources Board. Staff Report: Proposed Diesel Particulate 

Matter Control Measure For On-Road Heavy-Duty Residential and Commercial Solid 

Waste Collection Vehicles. June 6, 2003. 

ARB, 2003b. California Air Resources Board. Staff Report: Airborne Toxic Control 

Measure for Stationary Compression-Ignition Engines. September 2003. 

ARB, 2003c. California Air Resources Board. Staff Report: Airborne Toxic Control 

Measure for In-Use Diesel-Fueled Transport Refrigeration Units (TRU) and TRU 

Generator Sets, and Facilities Where TRUs Operate. October, 28 2003. 

ARB, 2004. California Air Resources Board. Staff Report: Airborne Toxic Control 

Measure for Diesel-Fueled Portable Engines. January 2004. 

ARB, 2005a. California Air Resources Board. Review of the California Ambient Air 

Quality Standard for Ozone. Staff Report, Initial Statement of Reasons for Proposed 

Rulemaking. October, 2005 http://www.arb.ca.gov/research/aaqs/ozone-rs/revstaff/rev-staff.htm#Summary
-35- 

ARB, 2005b. California Air Resources Board. Characterization of Ambient PM10 and 

PM2.5 in California. Technical Report. June 2005. 

http://www.arb.ca.gov/pm/pmmeasures/pmch05/stateover05.pdf

ARB, 2005c. California Air Resources Board. "Hot Spots" Public Notification, District 

Prioritization Scores and Risk Threshold Values, Last Updated on August 25, 2005. 

http://www.arb.ca.gov/ab2588/district_levels.htm

ARB, 2005d. California Air Resources Board. Staff Report: Proposed Amendments to 

the Exhaust Emission Standards For 2007-2009 Model-Year Heavy Duty Urban Bus 

Engines. July 29, 2005. 

ARB, 2005e. California Air Resources Board. Staff Report: Proposed Modifications to 

the Fleet Rule for Transit Agencies and New Requirements For Transit Fleet Vehicles. 

January 5, 2005. 

ARB, 2005f. California Air Resources Board. Staff Report: Proposed Diesel Particulate 

Matter Control Measure For On-Road Heavy-Duty Diesel-Fueled Vehicles Owned Or 

Operated By Public Agencies and Utilities. October 25, 2005. 

ARB, 2005g. California Air Resources Board. Staff Report: Regulation for Mobile 

Cargo Handling Equipment at Ports and Intermodal Rail Yards. October 2005. 

ARB, 2005h. California Air Resources Board. Staff Report: Proposed Regulation For 

Auxiliary Diesel Engines and Diesel-Electric Engines Operated on Ocean-Going 

Vessels Within California Waters and 24 Nautical Miles of the California Baseline. 

October 2005. 

ARB, 2005i. California Air Resources Board. Staff Report: Notice of Public Hearing to 

Consider Requirements to Reduce Idling Emissions From New and In-Use Trucks, 

Beginning in 2008. September 1, 2005. 

ARB, 2006a. California Air Resources Board. Area Designations and Maps 2006. 

Staff Report, Initial Statement of Reasons for Proposed Rulemaking, 

September 29, 2006. http://www.arb.ca.gov/regact/area06/adisor.pdf

ARB, 2006b. California Air Resources Board. Environmental Tobacco Smoke: A Toxic 

Air Contaminant. October 18, 2006. ftp://ftp.arb.ca.gov/carbis/regact/ets2006/isor.pdf

ARB, 2007a. California Air Resources Board. Staff Report: Proposed Regulation for 

In-Use Off-Road Diesel Vehicles. April 2007. 

http://www.arb.ca.gov/regact/2007/ordiesl07/ordiesl07.htm
-36- 

ARB, 2007b. California Air Resources Board. Staff Report: Proposed Regulation for 

Commercial Harbor Craft. September 2007. 

http://www.arb.ca.gov/regact/2007/chc07/chc07.htm

ARB, 2007c. California Air Resources Board. Staff Report: Regulation to Reduce 

Emissions from Heavy-Duty On-Road Drayage Trucks in California Port and Intermodal 

Rail Service. October 2007. 

http://www.arb.ca.gov/regact/2007/drayage07/drayage07.htm

ARB, OEHHA, 2002. California Air Resources Board and Office of Environmental 

Health Hazard Assessment. Staff Report: Public Hearing to Consider Amendment to 

the Ambient Air Quality Standards for Particulate Matter and Sulfates. May 3, 2002. 

ftp://ftp.arb.ca.gov/carbis/regact/aaqspm/isor.pdf

ARB, OEHHA, 2007. California Air Resources Board and Office of Environmental 

Health Hazard Assessment. Review of the Ambient Air Quality Standard for Nitrogen 

Dioxide. Staff Report January 5, 2007. http://www.arb.ca.gov/research/aaqs/no2-

rs/no2-doc.htm#TechSuppDoc

Arey J., Zeilinska, B., Atkinson, R. and A.M. Winer, 1988. Formation of Nitroarenes 

During Ambient High-Volume Sampling. Environ. Sci. Technol., 22:457-462. 

Diaz-Sanchez et al., 1999. Diaz-Sanchez, D.; Garcia, M.P.; Wang, M.; Jyrala, M.; 

Saxon, A. Nasal Challenge with Diesel Exhaust Particles Can Induce Sensitization to a 

Neoallergen in the Human Mucosa; J. Allergy Clin. Immunol. 1999, 104: 1183-1188. 

Diaz-Sanchez et al., 1996. Diaz-Sanchez, D.; Tsien, A.; Casillas, A.; Dotson, A.R.; 

Saxon, A. Enhanced Nasal Cytokine Production in Human Beings after in vivo 

Challenge with Diesel Exhaust Particles; J. Allergy Clin. Immunol. 1996, 98, 114-123. 

Frampton, 2000. Frampton, Mark W. Prepared for California Air Resources Board, 

California Office of Environmental Health Hazard Assessment. Nitrogen Dioxide: 

Evaluation of Current California Air Quality Standards with Respect to Protection of 

Children. September 1, 2000. 

Kittelson et al., 1999. Kittelson, D.B., Arnold, M., Watts, W.F. Review of Diesel 

Particulate Matter Sampling Methods. Final Report. University of Minnesota, 1999. 

www.me.umn.edu/centers/cdr/Proj_EPA.html. 

Lloyd, A.C.; Cackette, T.A., 2001. Diesel Engines: Environmental Impact and Control; J 

Air Waste Manage. Assoc. 2001, 51: 809-847 

http://www.arb.ca.gov/research/seminars/lloyd/AWMA2001/JAWMADieselCriticalRevie

w.pdf

NCSA, 2007. National Center for Statistics and Analysis. 2006 Traffic Safety Annual 

Assessment – A Preview. July 2007. http://www-nrd.nhtsa.dot.gov/pubs/810791.pdf
-37- 

OEHHA, 1998. Office of Environmental Health Hazard Assessment. Proposed 

Identification of Diesel Exhaust as a Toxic Air Contaminant: Health Risk Assessment for 

Diesel Exhaust; Appendix III, Part B. Sacramento, CA, 1998 

SCAQMD 2000, Multiple Air Toxics Exposure Study in the South Coast Air Basin 

(MATES-II), Final Report, Chapter 5. March, 2000) 

Takano et al., 1998. Takano, H.; Ichinose, T.; Miyabara, Y.; Shibuya, T.; Lim, H.B.; 

Yoshikawa, T.; Sagai, M., 1998. Inhalation of Diesel Exhaust Enhances Allergen-related 

Eosinophil Recruitment and Airway Hyperresponsiveness in Mice; Toxicol. Appl. 

Pharmacol. 1998, 150, 328-337. 

U.S. EPA, 2000. United States Environmental Protection Agency, Assessment and 

Standards Division, Office of Transportation and Air Quality. Regulatory Impact 

Analysis: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur 

Control Requirements. EPA420-R-00-026, December 2000, Chapter II. 

U.S. EPA, 2001. United States Environmental Protection Agency. Control of Emissions 

of Hazardous air Pollutants from Mobile Sources; Final Rule (66FR 17230 – 17273, 

March 29, 2001. 

U.S. EPA, 2002. United States Environmental Protection Agency. Office of Research 

and Development, Health Assessment Document for Diesel Engine Exhaust. 

EPA600/8-90/057F, May 2002. 
-38- 
-39- 

V. VEHICLE DESCRIPTIONS AND MANUFACTURERS

This chapter describes the diverse array of on-road vehicles typically used by 

businesses operating in California and that would be subject to the proposed regulation. 

It includes tables of engine, truck and bus manufacturers, descriptions, and 

photographs of various vehicle types with a range of body types. 

A. Overview 

Trucks and buses are used to both transport both people and goods and to provide 

services. They are used in almost every industry sector. Trucks and buses are 

configured differently for each application, thereby optimizing operational and fuel 

efficiency. Trucks and tractors (trucks designed specifically for pulling or hauling 

trailers) are configured differently depending on if they are being used to support a 

particular vocation or to primarily transport goods. 

There are two basic truck configurations: tractor-trailer combinations and single unit 

trucks. Within each of these configurations, the vehicles will be designed differently 

depending on how they will be used. For example, tractors used to transport heavy 

equipment will have 500 to 600 horsepower (hp) engines, heavy frame construction, 

heavy front axles, 18 speed transmission, and tandem rear axles. The gross 

combination weights of these vehicles are 80,000 pounds or more. This compares with 

a standard tractor used locally to deliver beverages, which will have a 200 hp engine, a 

light frame configuration, single rear axle, and a 6 speed transmission. 

Single unit vehicles range in weight class from 14,000 to well over 33,000 pounds. In 

addition, single unit trucks are generally sold as a cab and chassis, and can have 

hundreds of different bodies attached to transport dry goods, liquids, or perform a given 

service function such as cleaning out sewers, servicing equipment, or feeding cattle. 

Some single unit vehicles are also configured to carry its load and pull a trailer. 

Similarly, buses range widely in size and configuration generally based on the number 

of passengers that can be carried. Shuttle buses carry a small number of passengers 

and operate locally, whereas motorcoaches are built to carry large number of 

passengers and travel longer distances. 

B. Vehicle Classes 

On-road vehicles are grouped by their gross vehicle weight rating (GVWR), ranging 

from class 1 to class 8. Class 1 to 3 are considered light-duty vehicles and weigh less 

than 14,000 pounds. Class 4 to 8 are vehicles with GVWR over 14,000 pounds and are 

subject to the on-road proposed regulation. In the trucking industry, GVWR is the gross 

vehicle weight (GVW) of a single unit truck plus its cargo weight or the GVW of a tractor 

plus the rated pulling capacity. These classifications are used consistently throughout 

the industry. Table V-1 shows the weight classifications as defined by the U.S. 

Department of Transportation (DOT). 
-40- 

Table V-1: Weight Classification Defined by U.S. DOT 

Weight Class Minimum 

GVWR (lbs) 

Maximum 

GVWR (lbs) 

VIUS* 

Category 

Common 

Category 

Class 1 6,000 Light-duty Light- Duty 

Class 2 6,001 10,000 Light-duty Light-Duty 

Class 3 10,001 14,000 Medium-duty Light-Duty 

Class 4 14,001 16,000 Medium-duty Medium-Duty 

Class 5 16,001 19,500 Medium-duty Medium-Duty 

Class 6 19,501 26,000 Light-heavy Medium-Duty 

Class 7 26,001 33,000 Heavy-heavy Heavy-Duty 

Class 8 33,001 Heavy-heavy Heavy-Duty 

*VIUS 2002 Vehicle Inventory and Use Survey 

C. Engine and Vehicle Manufacturers 

1. On-Road Diesel Engines Manufacturers 

On-road diesel engines are manufactured globally for various duty ratings by different 

manufacturers. Some engine manufacturers produce engines for their own vehicles, 

but most sell them to other vehicle manufacturers. Engine manufacturers certify 

specific engine families to meet California engine emission standards within a specific 

service class or duty rating that is slightly different than the DOT vehicle rating. The 

engine service class used by vehicles rated greater than 14,000 pounds GWVR is the 

heavy-duty service class. The heavy-duty service class has three subclasses. Light 

heavy-duty engines are certified for use in vehicles up to 19,500 pounds GVWR, 

medium heavy-duty engines are certified for use in vehicles up to 33,000 pounds 

GVWR and heavy-heavy duty engines are certified for use in vehicles above 33,000 

pounds. Operation of engines in these weight ranges ensures that the engine 

emissions meet California’s engine exhaust emission standards. Table V-2 shows a list 

of common on-road engine manufacturers. 

Table V-2: Common Manufacturer of On-Road Engines 

Caterpillar Cummins Daimler Benz 

Detroit Diesel GMC Ford 

Hino Hyundai International 

Isuzu Mack Mitsubishi 

Navistar Volvo 

In 2005 (the most recent year for which data is available), Caterpillar, Cummins and 

Detroit Diesel accounted for the majority of the engines produced to power class 8 

vehicles. This is shown below in Figure V-1. 
-41- 

Figure V-1: Market Shares of Diesel Engine Manufacturers 

Cummins

25%

Caterpillar

29%

Mack

& Volvo

26%

Detroit

Diesel

20%

As can be seen in Figure V-1, their respective market shares were 29 percent, 25 

percent, and 20 percent (Diesel Progress, 2005). However, none of these engine 

manufacturers manufacture vehicles. The remaining market share of 26 percent was 

primarily divided between Mack and Volvo trucks who utilize their own engine in the 

vehicles they manufacture. Also small percentage of Daimler Benz diesel engines were 

used in Freightliner and Sterling class 8 trucks. 

For class 4 through 7 vehicles, it is much more common for truck manufacturers to 

produce their own engines. Common class 4 through 7 truck manufacturers that 

produce their own engines include Ford, GMC, Hino, Isuzu, Mitsubishi, and 

International. 

2. On-Road Vehicle Manufacturers 

Presently, nearly 75 percent of vehicle manufacturers purchase engines from engine 

manufacturers, such as Caterpillar and Cummins, to fit their applications (Ward’s, 

2007). Truck and bus manufacturers design and manufacture their vehicles by 

integrating the engines into the frame of a complete vehicle or into a cab and chassis 

configuration with no bed or body attached. 

All vehicle manufacturers produce different body types for a variety of applications. 

Most new tractors are sold with a wide range of special order options for the buyer to 

optimize the tractor for its intended application. In contrast, single unit trucks are 

primarily manufactured in somewhat more standardized cab and chassis configurations 

where the buyers select the configuration that most closely meets their needs, and add 

on the aftermarket bed and other equipment for vocational applications. 

Many vehicle manufacturers tend to specialize in a particular weight class range or body 

style. For example, Ford, GMC and Mitsubishi produce light- to medium-duty trucks, 
-42- 

while Freightliner and Peterbilt primarily offer heavy-duty (class 8) tractors. Table V-3 

list the common manufacturers of trucks and tractors. 

Table V-3: Common Manufacturers of Trucks and Tractors 

Amertek Autocar Brockway Capacity 

Champion Chevrolet Diamond Reo Dodge 

Eagle Ford Freightliner GMC 

Hino Hyundai International Isuzu 

Kenworth Lodal Mack Magnum 

Marmon Mercedes-Benz Mitsubishi Fuso Nissan 

Oshkosh Ottawa Peterbilt Sterling 

UD Volvo Western Star White 

Similarly, bus manufacturers also service particular market segments. For example, 

Prevost and MCI primarily manufacture motorcoaches, Ford and GMC manufacture 

various shuttle buses, and Bluebird specializes in producing school buses. Table V-4 

list the common manufacturer of buses and shuttle buses. 

Table V-4: Common Manufacturers of Buses and Shuttle Buses 

Bluebird Carpenter Champion 

Collin Eldorado National Federal 

Ford Freightliner Gillig 

Girardin Minibus Glaval Bus GMC 

Gosher Coach Grumman IC 

International Krystal Koach MCI 

Millennium New Flyer North American Bus 

Nova Bus Orion Prevost 

Setra Starcraft Thomas 

TMC Trident Van Hool 

Williams Bus & Specialty World Trans 

D. Vehicle Types 

There are thousands of vehicle types that will be subject to the proposed regulation. 

The following section provides an overview of a limited number of common vehicle 

types affected. Typical prices for new and used vehicles described below are provided 

in Appendix J. 

1. Overview of Conventional Trucks 

a) Over the Road Tractor 

The most common tractors have either single or tandem rear axles. A single drive axle 

tractor is often used to pull shorter trailers or lighter loads and is easier to maneuver. 
-43- 

Day cabs are mostly single axle vehicles, and frequently used for shorter trips that can 

be completed during the course of a day. Tandem axle tractors are commonly used in 

long haul operations and for transporting heavier loads. Tractors with sleeper and 

tandem axles are predominately used for longer trips that require overnight stays. As 

conventional tractors age, they are typically sold into the secondary truck market. Here, 

they may be used locally or modified to become single unit vehicles with an attached 

bed. 

Most conventional tractors are optimized for specific tasks, i.e., meaning that for a 

specific application like long haul, the tractor has a properly sized engine and drive train. 

The performance of a tractor can be altered by changing the engine size, and by 

changing the transmission and rear differential gear ratios. For example, a “heavy 

hauler”, which hauls heavy loads at low speed, may trade speed for load carrying power 

by utilizing a lower gearing transmission and higher differential ratio without modifying 

the engine size. Various engine and drive train combinations allow the conversion of 

tractors from one application to another. 

b) Cab Over 

A cab over is a body style of tractor that has a 

vertical front or “flat face”, with the cab of the truck 

above the engine. The cab over design makes 

the tractor shorter than a conventional design 

where the engine is placed in front of the cab. 

Typically, the cab over is used in certain 

operations because it allows the operator to tow a 

longer trailer or have a longer cargo area while 

providing the same overall length as a 

conventional tractor trailer, thereby satisfying 

California vehicle length law restrictions. 

Compared to a conventional tractor, the cab over 

has the advantage of being more maneuverable. 

However, it also has disadvantages in that the entire cab needs to be tilted forward to 

access the engine, and it is somewhat more difficult to enter and exit. Demand for cab 

Cab Over Tractor

Tandem Axle Tractor with Sleeper Single Axle Day Cab
-44- 

over tractors in the United States has declined to a point where truck manufacturers 

ceased production of cab over tractors in 2006. 

(1) Glider Kit for Cab Over 

A glider kit is a complete assembly of cab, front axle, wheels, and frame, plus all 

standard equipment (less the engine) that can be ordered from the manufacturer. The 

power train components and a new or remanufactured engine will need to be installed 

to make the complete vehicle. In some cases, the manufacturer will install the engine if 

it is purchased at the same time as the glider kit. Since the glider kit is not considered a 

new truck, the kit is exempt from federal excise tax. 

 

c) Cab and Chassis 

The cab and chassis is a single unit truck without a bed or body attached. Cab and 

chassis are available in all weight classes. While nearly all single unit trucks have fairly 

simple bolt-on bodies that are supported by the truck frame, there are literally thousands 

of different body types. In some applications the body will be replaced at least once 

before the end of the truck’s useful life. In other instances, the body may be transferred 

to another truck. 

The truck bed or body may vary from a simple flatbed or dry van (as described later in 

this chapter) with no moving parts to a body attachment with a tilt bed or having other 

Box Van Body Cab and Chassis

Cab and Chassis with Dump Body

Cab and Chassis with Tank Body
-45- 

moving parts such as a live floor or boom for lifting cargo. Power to operate the body is 

typically provided through a power take off (PTO) system (which draws power from the 

vehicles’ main engine), which is a fairly common accessory to the existing transmission 

for most trucks. In only rare instances, such as with cement mixers, is the body welded 

to the frame for added strength. 

Cab and chassis trucks also serve as the foundation for some manufacturers to produce 

complete vehicles (such as where the body is fully integrated with the rest of the truck), 

such as with street sweepers. 

2. Common Vehicle Types 

a) Dump Trucks 

A dump truck (or production truck) is used for transporting loose material such as sand, 

gravel, or dirt for construction activities. There are several configurations of dump 

trucks, including standard dump, superdumps, transfer dumps, end dumps, and bottom 

dumps. 

A standard dump truck is a full truck chassis with 

a dump body mounted to the frame. The dump 

body is raised by a hydraulic ram mounted 

forward of the front bulkhead, between the truck 

cab (traction unit) and the dump body. The 

tailgate can be configured to swing on hinges or 

it can be configured in the “High Lift Tailgate” 

position, wherein pneumatic rams lift the gate up 

and open above the dump body. The short 

wheelbase of a standard dump truck makes it 

more maneuverable than the higher capacity tractortrailer combination of end dumps and bottom dump 

trucks. 

A superdump truck is a standard dump 

truck equipped with an additional liftable, 

load-bearing axle. The additional axle 

increases the gross weight allowing for 

additional payload. When the truck is 

empty, the additional axle toggles up off the 

road surface on two hydraulic arms. A 

typical superdump truck is equipped with a 

hydraulically operated open-box bed hinged 

at the rear, the front of which can be lifted 

up to allow the contents to be deposited on 

the ground behind the truck at the delivery 

site. 

Medium Duty Standard 

Dump Truck

Superdumps
-46- 

A transfer dump is a combination of a standard 

dump truck pulling a separate trailer whose 

rear box is capable of being transferred from 

the trailer frame rails onto the empty dump bed 

on the truck. It is predominantly used to 

transport asphalt, aggregates, or other small 

material. The second container on the trailer 

rides on small wheels and rolls on rails off of 

the trailer frame and into the empty main dump 

box. The rear box locks onto the dump bed on 

the truck allowing it to be dumped as a single unit. 

After the load is dumped the second container is 

rolled out of the truck and back on to the trailer rails. 

The key advantage of this configuration is to maximize payload capacity without 

sacrificing the maneuverability of the standard dump truck. Transfer trucks are uniquely 

configured for operation in California and are not used in other parts of the country. 

End dump and bottom dump trucks 

are both tractor-trailer combinations. 

Both configurations utilize either 

single rear axles or tandem rear 

axles to tow the dump trailers. The 

end dump trailer uses a hydraulic 

hoist on the trailer to dump and is 

powered by the tractor. Its 

advantage is rapid unloading. The 

bottom dump trailer can be a single 

long trailer or a double trailer with a metal 

hopper configuration with angled sides. It pours materials out of the bottom as it moves 

along the road. This is used whenever small amounts of material are needed over a 

large area, such as on a roadway under construction. 

b) Body Load 

The body load truck is a truck with 

equipment integrated directly into the 

frame of the truck. The equipment is 

built on the truck piece by piece 

(above and below the frame rails) as 

opposed to having it installed on a bed 

that is bolted on top of the truck rails. 

These trucks usually have heavy 

frame with two or more axles. The 

integrated equipment can cost more 

than a half million dollars and would 

have to be dismantled piece by piece to be 

Bottom Dump Truck

Body Load Blender

Transfer Dump Truck
-47- 

moved to a different cab and chassis. An example of a body load application is a 

vehicle used for the fracturing operation performing in the oil field to increase well 

production. 

c) Tank Truck 

A tank truck is a vehicle designed to carry 

liquefied loads, dry bulk cargo or gases. Many 

variants exist due to the wide variety of liquids 

that can be transported. The tank on the 

trucks may be insulated or non-insulated, 

pressurized or non-pressurized, and for single 

load or built with internal divisions for multiple 

loads (such as to carry different grades of 

gasoline). A large tank truck typically has a 

capacity of up to 8,000 gallons. A smaller tank 

truck typically has a capacity of less than 3,000 

gallons, but can be increased to as much as 9,000 

gallons through the use of a trailer, commonly referred to as a “pup”. 

A tank truck is distinguished by 

its shape, usually a cylindrical 

tank upon the vehicle lying 

horizontally. Some other less 

visible distinctions among tank 

trucks are their intended use: 

compliance with human food 

regulations, refrigeration 

capability, acid resistance, 

pressurization capability, etc. 

d) Vacuum Truck 

A vacuum truck is a tank truck with a pumping 

system to pump and store fluid for transporting 

from one location to another. The pumping 

system and the accessories are normally 

mounted on the truck and power by a PTO unit. 

The vacuum tank may have internal divisions to 

store both the cleaning fluids to be used at the 

job site, as well as the generated waste. 

e) Box Truck (Dry Van) 

A box truck, also known as a cube truck, cube 

van, bob truck, or box van, is a truck with a cube 

shaped cargo area. These types of truck vary in 

length, and some have tandem axles. They 

Water Trank Truck

Fuel Tank Truck with Pup

Dry Van

Vacuum Truck
-48- 

usually have a garage like rear door that rolls up. On some box trucks, the cargo area is 

accessible from the cabin via a small door. Box trucks are used by companies to haul a 

wide variety of items locally. They are also commonly used as retail rental moving 

trucks. 

f) Refrigerated (Reefer) Truck 

A refrigerated truck is a highly insulated van truck 

designed to carry perishable freight at low 

temperatures. Refrigerated trucks can be icecooled, be equipped with any one of a variety of 

mechanical refrigeration systems, or can utilize 

carbon dioxide (either as dry ice or in liquid form) 

as a cooling agent. 

g) Motorcoach 

Motorcoaches are generally designed and 

operated to transport passengers over long 

distances. To make the trip comfortable, these 

coaches often have reclining upholstered seats, a 

toilet, and air-conditioning. Because they are 

designed for long distance travel (instead of 

having to take on and discharge many passengers 

over very short runs), it is rare for a motorcoach to 

have more than one door (save for a wheelchairlift access) or standing room. As these vehicles 

age, their use tends to change such that they are 

used for shorter trips. 

h) Flatbed Truck 

A flatbed truck is a type of truck that has an 

entirely flat, level body with no sides or roof. 

This allows for quick and easy loading of goods 

using a crane or forklift, and is typically used to

transport heavy loads that are not delicate or 

vulnerable to precipitation. They are also used 

for unusually shaped loads that require more 

space than is available on a closed body. 

i) Concrete (Cement) Truck 

A concrete truck (also known as in-transit 

mixers) is designed to transport concrete from 

a factory/plant to a construction site. Typically,

they are charged with dry materials and water 

at the factory/plant, with the mixing occurring 

Reefer Truck

Motorcoach

Concrete Truck

Flat Bed Truck
-49- 

Lattice Boom Truck Crane Two-Engine All Terrain Crane

Bucket Truck

during transport. The interior of the drum on a concrete truck is fitted with a spiral 

blade. The drum is typically powered by a PTO unit. In one rotational direction, the 

concrete is pushed deeper into the drum while the concrete is being transported to the 

building site. When the drum rotates in the other direction, the screw-type arrangement 

“discharges”, or forces the concrete out of the drum, typically into a chute. 

j) Bucket Truck 

A bucket truck has a working platform, such as like

a bucket at the end of a hydraulic lifting system. 

These vehicles are also known as a boom (or man) 

lift truck. They are used to support work at a high 

elevation above ground. The bucket is designed for

a person to stand in and work from. The controls for 

manipulating the position of the bucket are in or 

near the bucket. Another set of controls are on the 

truck for controlling the lifting system when the 

operator is on the ground. 

 

k) Cranes 

Lattice boom cranes can be both truck mounted or crawler (truck) mounted. With the 

truck mounted version, the crane's upper structure is mounted on a truck style carrier 

and can travel at highway speeds. Major sections of the crane’s boom are usually 

removed and transported separately on some larger units. 

A lattice boom crane is typically the best choice 

when the job requires long, vertical reaches, or 

significantly large lifts. The advantage of a 

lattice boom crane is that the mast is relatively 

light in comparison to a telescope crane, making 

it much stronger in terms of working radius. A 

lattice boom crane typically provides higher lifting 

capacity for less vehicle weight, making a 100 

Two Engine Truck Mounted Crane
-50- 

Single Engine Boom Truck

ton capacity lattice boom crane outperform a 200 ton capacity telescopic crane. 

Two-engine all terrain cranes combine truck crane highway speeds with the off-road 

performance characteristics of rough terrain cranes. Multiple axles (steer, drive and 

tag) distribute the load. Capacity on these machines can reach 1,000 tons. 

Two-engine truck mounted cranes have a long reach, high capacity booms and highway 

speed capabilities. Truck mounted cranes sit on a commercial truck chassis with a 

motive engine or secondary engine to power the crane operation. 

l) Boom Truck 

Single engine boom trucks look similar to twoengine truck mounted cranes. They utilize a 

telescoping boom and perform the same 

functions as all-terrain and truck mounted 

cranes, and have a lift capacity of about 40 tons. 

The boom is powered by the motive engine, 

eliminating the need for a secondary engine. 

Boom trucks come with fixed operator control 

stations or cabs that swing with the cranes. 

m) Street Sweepers 

Sweepers are designed to removed dirt and debris from roadways, and can be 

categorized into two main types: mechanical and air sweepers. Mechanical sweepers 

are equipped with water tanks and sprayers used to loosen particles and reduce dust. 

The brooms gather debris into a main collection area from which it is vacuumed and 

pumped into a collection bin. 

An air street sweeper uses forced air to 

create a swirling knifing effect inside a 

contained sweeping head and then uses 

the negative pressure on the suction side 

to lift the road debris into a containment 

hopper. The debris laden air is then 

filtered and discharged. Sweepers may 

have a single engine with that provides 

power to propel the sweeper and to 

operate the broom or vacuum, or may 

have a second (auxiliary) engine to 

separately operate the broom or vacuum. Two Engine Regenerative Air Sweeper
-51- 

n) Tow Truck 

A tow truck (also called a wrecker) is a 

vehicle used to transport disabled vehicles 

from one location to another (generally a 

repair garage), to recover disabled 

vehicles, and to assist in clearing streets 

and highways of breakdowns and 

collisions. Businesses and government 

agencies with a large fleet of vehicles may 

own one or several tow trucks for the 

purposes of towing their own vehicles. 

They are also used to impound vehicles for 

various reasons such as parking violations. The 

towing and lifting mechanisms on a tow truck are 

powered by a PTO unit. 

o) Drill Rig 

A drill rig is a machine which drills holes 

(usually called boreholes) and/or shafts 

into the ground. Drill rigs are used to 

drill water wells, oil wells, or natural gas 

extraction wells. They are used to 

sample sub-surface mineral deposits, 

test rock, soil and groundwater physical 

properties, and to install sub-surface 

fabrications, such as underground utilities, 

instrumentation or tunnels. Drill rigs can be 

mobile equipment mounted on trucks, tracks or trailers, and can vary significantly in 

size. In some drill rigs, the drilling operations are supported by the drive engines using 

PTO. In other cases, dedicated secondary engines are used to provide the power. 

p) School Buses 

School buses are generally classified in one of four 

categories. Type-A school buses are the smallest 

school buses, and they are typically gasoline-fueled, 

although they can also be diesel-fueled. They, 

typically, tend to be below 14,000 pounds GVWR, and

have a driver side door. Type-B school buses are 

larger, typically greater than 10,000 pounds GVWR, 

and can be gasoline or diesel-fueled. Type-B school 

buses are normally used for special needs student 

transportation. Type-C school buses, also called 

conventional school buses, are typically diesel fueled 

and have the engine in the front of bus. These school 

buses tend to be above 14,000 pounds GVWR. 

Wrecker Truck

Two Engine Drill Rig

School Bus
-52- 

Type-D school buses, also called transit style school buses, are almost always dieselfueled, having a rear-mounted engine. Type-D school buses can be greater than 

33,000 pounds GVWR, and having the ability to transport up to 90 students and 

passengers. 

3. Agricultural Vehicles 

Agricultural vehicles include a wide variety of vehicles used on and off the farm for a 

number of different purposes. 

a) Farm Vehicles 

Farm use vehicles are typically single unit trucks with bodies uniquely designed for 

farming operations such as fertilizing, feeding, spraying, etc. While on farm vehicles 

typically have on-road engines and can travel on city streets, they spend a majority of 

their time operating off-road on the farm. Some have special equipment (SE) plates 

while others are not registered at all. 

When a single unit truck needs replacement, typically the truck bed can be removed 

and transferred to another new or used single unit truck. However, it is not uncommon 

for some on farm vehicles having a new truck body installed on a used single unit truck 

or a used tractor that has been converted to a single unit truck. 

Livestock Feeder Farm Sprayer

Spreader Silage
-53- 

b) Farm to First Processing 

Farm vehicles also include vehicles used to transport commodities to processing 

facilities. For transporting commodities, tractor trailer combinations are typically used. 

This would include the use of tractors and refrigerated trailers to transport lettuce as 

well as transporting cattle in livestock trailers. 

A cotton module truck is either a single unit truck or a tractor-trailer that is used to 

transport the compacted cotton block from the field to the cotton gin for processing. 

Single unit cotton module trucks have a long chassis design to accommodate the length 

of the cotton module. The body or trailer has a built-in mechanism that pulls the vehicle 

underneath the compacted cotton module (bale) while in the field. In California, cotton 

module trucks mostly have SE plates allowing for short distance, on-highway travel. 

Normal commercial plates are needed only if the cotton module is used for long 

distance hauling on a major freeway. 

The wheelbase for a single unit cotton 

module vehicle is over 300 inches, which is 

longer than most other single unit trucks. 

This means that the frame needs to be 

special ordered prior to configuring a new 

cotton module truck. It also requires a 

double frame to strengthen the chassis due 

to its overall length. 

A new truck with a cotton module body 

costs about $190,000. Transferring an 

existing cotton module body to a used single unit truck is possible, but finding an 

existing truck with an appropriate wheelbase and frame is challenging. An existing 

cotton module body can be transferred to a properly configured new truck for about 

$130,000. 

Cotton Module
-54- 

c) Chemical & Fertilizer Delivery Truck 

Chemicals used on the farm include pesticides and fertilizer among others. Both come 

in dry or wet form and are generally transported to the farm with either single unit trucks 

or truck-tractor and trailer combinations. Certain types of fertilizers are considered 

hazardous materials and their transportation is highly regulated and all pesticides and 

other crop protection chemical are considered hazardous materials. Transportation of 

these products requires special vehicles markings in the form of U.S. DOT placards and 

transportation vessels must meet strict safety regulations. 

4. Logging Truck 

The transportation of raw, harvested logs from a 

forest is done via tractor trailer. This combination 

consists of a tractor and a long metal beam 

connecting the trailing two-axle set. This beam is

typically small in diameter, and several feet above

the road surface. The operational requirements of a 

logging truck make it different from a conventional

tractor. 

Although it may be used to transport lumber 

products to a specific location (similar to work done 

by a conventional tractor), the majority of the time it 

is utilized to move harvested logs from a fell site in 

the forest to the saw mill for processing. Log trucks are somewhat unique in that they 

work in the forest and negotiate steep dirt logging roads. To perform this work, they 

have larger frame rails, 18 speed heavy duty transmissions, 46,000 pounds rear 

differential/axle sets, heavy duty rear wheels, severe service cabs, and heavy duty rear 

suspensions. 

E. References 

Diesel Progress, 2005. Diesel Progress North American Edition. Heavy Truck Sales on 

a Roll in ’05. October 2005. 

National 2002 VIUS. U.S. Census Bureau 2002 Economic Census: Vehicle Inventory 

and Use Survey. EC2TV-US. Issued December 2004 

Chemical & Fertilizer Truck

Logging Truck
-55- 

Ward’s, 2007. Ward’s Automotive Group. U.S. Truck Sales by GVW Class and Source, 

2007, Copyright 2008. Subscription Service. http://www.wardsauto.com
-56- 
-57- 

VI. ESTIMATED EMISSIONS FROM ON-ROAD DIESEL TRUCKS AND BUSES

This chapter describes the emissions inventory that was developed for the proposed 

regulation for heavy-duty diesel vehicles operating in California. It summarizes how 

multiple data sources were utilized to develop estimates of both the vehicle population 

and VMT in California; how ARB’s on-road emissions inventory model (EMFAC) was 

used to assess emission rates, and how the emissions estimates were developed. The 

chapter presents statewide emissions estimates in the baseline, without regulation. 

Additional details are provided in Appendix G. 

A. Methodology 

Emissions are calculated as the product of a population of vehicles, the number of miles 

each vehicle travels, and the emission rates per mile. Beneath this simple equation lies 

a series of data and assumptions about the population, miles traveled, and emission 

rates per vehicle model year in a given calendar year, growth and attrition estimates, 

deterioration, and other factors that affect emissions estimates. Staff updated approach 

for estimating commercial in-use on-road heavy-duty diesel vehicle emissions builds on 

the below equation by applying it separately for selected categories of vehicles. These 

categories were selected by evaluating different groups of vehicles that have travel, 

service, size, age or other characteristics in common. Staff’s methodology used the 

following equation: 

 

∑MY, C (POPMY, C X AC MY, C X ER MY, C) = EMSCY, 

where: POPMY, C is the population of vehicles for model year MY within each 

inventory category C for a given calendar year; 

ACMY, C is the accrual rate (miles traveled per year) per vehicle by model year 

MY and inventory category C in a given calendar year; 

ERMY, C is the calculated emission rate, in grams pollutant per mile driven, 

assuming statewide speed travel distributions in EMFAC2007 and fleet 

specific cumulative mileage accrual over the life of the vehicle, by model 

year MY and inventory category C; 

EMSCY is the emissions calculated in tons per day for a given calendar year. 

In this new analysis, staff assessed a population and model year distribution for each 

vehicle category. Staff also estimated accrual rate by model year for the category and 

cumulative mileage accrual (odometer) by model year. Because vehicles can move 

between categories as they age, staff assessed the movement of vehicles between 

categories in order to develop more accurate cumulative mileage accrual estimates. As 

a result, cumulative odometer readings by model year will not necessarily be consistent 

with accrual schedules for each specific category. Criteria pollutant emission rates are 

developed using the 2007 version of EMFAC (EMFAC2007) and statewide speed 

distributions, and emission rates were adjusted for modeled odometer readings, by 

category. Carbon dioxide (CO2) emission rates were developed based on analysis of 

fuel economy trends over time and across engine control technologies. 
-58- 

B. Population and Activity 

For the purposes of this regulation, the truck and bus population was divided into four 

broad inventory categories. Heavy-heavy duty diesel trucks were those trucks that 

exceed 33,000 GVWR. They may be combination trucks (tractor-trailer) or single unit 

trucks. Medium-heavy duty diesel trucks were those trucks with a GVWR between 

14,000 and 33,000 pounds. These trucks are most often single units, although some 

are combination trucks. The third category represented two types of buses: school 

buses and other buses. The ‘other’ bus category included primarily intercity, charter, or 

private buses that are not used to transport school children and are not operated as 

public transit buses. The final category was power take off, which represents the use of 

on-road engines to power auxiliary applications, such as a drill rig or concrete truck. 

1. Base Year Population, Age Distribution, and Mileage Accrual 

Table VI-1 summarizes the data sources that were used to develop estimates of vehicle 

population and activity, including annual average mileage accrual. 
-59- 

Table VI-1: Data Sources Used to Develop Population and Activity Estimates 

Type / 

Category Population Activity 

Heavy-Heavy / 

Out-of-State 

CA Department of Motor Vehicles (DMV) 

International Registration Plan (IRP) reports; 

adjusted to account only for vehicles that enter 

California. Model-year distribution from IRP 

data and UC Davis survey. Category split 

between neighboring states (WA, OR, NV, AZ, 

ID) vs non-neighboring states. 

Vehicle Inventory and Use Survey 

(VIUS) (2002) data analyzed to 

assess accrual for vehicles in any 

state that travel across state lines 

(registered in IRP program). Fraction 

of mileage accrued in California 

estimated using IRP data samples. 

Total activity in out-of-state vehicles 

by state of registration from 

International Fuel Tax Agreement 

Data (IFTA). 

Heavy-Heavy / 

CaliforniaInterstate 

DMV CA IRP reports provide population by 

model year 

VIUS for nationally registered 

vehicles in IRP as above. CA IRP 

reports fraction of mileage accrued in 

CA, and IFTA reports for total 

mileage. 

Heavy-Heavy / 

In-State Tractor 

DMV registration data provides population by 

model year and body type. Adjusted to 

subtract specific fleets such as utility, drayage, 

and others. 

VIUS data for California-registered 

tractors. 

Heavy-Heavy / 

In-State Single 

DMV registration data provides population by 

model year and body type. Adjusted to 

subtract specific fleets such as utility and 

others. 

VIUS data for California-registered 

single unit vehicles. 

Heavy-Heavy / 

Drayage 

Tractors 

Population and age distributions estimated 

using license plate and gate count surveys 

conducted at the Ports of Los Angeles, Long 

Beach, and Oakland. 

Total mileage estimated using tripbased model developed for ARB 

Drayage Truck Regulation. Mileage 

accrual assumed equivalent to the 

total miles traveled by drayage trucks 

divided by the total number of trucks. 

Heavy-Heavy / 

Agricultural 

Vehicles 

Age distribution from survey; population 

extrapolated from survey results; specialty 

vehicles estimated from survey and DMV 

registration data. 

Accrual from in-use on-road diesel 

vehicle survey 

Heavy-Heavy / 

Utility Vehicles 

Population and age of vehicles registered to 

public and private utilities in DMV database. 

Surveys conducted for ARB Public 

Agency & Utility Fleet Rule. 

Medium-Heavy / 

In-State 

Vehicles 

Population and age distribution in DMV 

registration data 

VIUS 2002 data representing 

California registered medium-heavy 

duty diesel vehicles. 

Medium-Heavy / 

Interstate 

Vehicles 

Population estimated from IRP reports 

VIUS 2002 data representing 

California-registered medium-heavy 

duty diesel vehicles. 

Medium-Heavy / 

Agricultural 

Vehicles 

Age distribution from survey; population 

extrapolated from survey results; specialty 

vehicles estimated from survey and 

registration data. 

Accrual from in-use on-road diesel 

vehicle survey 

Medium-Heavy / 

Utility Vehicles 

Population and age of vehicles registered to 

public and private utilities in DMV database. 

Surveys conducted for ARB Public 

Agency & Utility Fleet Rule. 

Buses / School California Highway Patrol data ARB school bus surveys 

Buses / Other EMFAC2007 EMFAC2007 

Other / Power 

Take-Off 

No population estimated. Total fuel usage 

provided by California State Board of 

Equalization; age distribution assumed same 

as in-state single unit vehicles 

Fuel usage converted to equivalent 

mileage assuming EMFAC speed 

distributions and fuel economy. 
-60- 

2. Base Year Population and VMT by Category and Fleet Size 

Most of the inventory categories described in Table VI-1 are further split by fleet size. 

To achieve the fleet size split by inventory category, ARB staff reviewed California 

Department of Motor Vehicles (DMV) registration data by name and address and 

grouped vehicles by fleet. This resulted in an age distribution by fleet size (fleets of one 

vehicle, two or three vehicles, and four or greater) for inventory categories in the DMV 

registration database. Neighboring out-of-state vehicles (those registered in Arizona, 

Nevada, Oregon, and Idaho) were assumed to have the same fleet size distribution as 

California registered IRP vehicles; for non-neighboring out-of-state vehicles, staff 

analyzed sample International Registration Program (IRP) data. Mileage accrual was 

assumed to be the same within each inventory category regardless of fleet size. Table 

VI-2 provides the population, VMT-weighted average age, and total VMT in calendar 

year 2008, by inventory category and fleet size. 

Table VI-2: 2008 Population, VMT, and VMT-Weighted Average Age by Inventory 

Category, Fleet Size, and Mileage Thresholds 

Fleet Source Population VMT/day 

VMT-Weighted 

Average Age 

Heavy-Heavy Non-Neighboring Out-of-State Vehicle 450,658 12,194,654 3.1 

 Owner-operator vehicle above 7500 miles/yr 6,955 192,875 3.1 

 Owner-operator vehicle below 7500 miles/yr 180 188 8.3 

 2 vehicle fleet above 7500 miles/yr 2,125 58,926 3.1 

 2 vehicle fleet below 7500 miles/yr 55 58 8.3 

 3 vehicle fleet above 7500 miles/yr 1,505 41,740 3.1 

 3 vehicle fleet below 7500 miles/yr 39 41 8.3 

 Large fleets above 7500 miles/yr 428,702 11,889,217 3.1 

 Large fleets below 7500 miles/yr 11,097 11,610 8.3 

 

Heavy-Heavy Neighboring State Out-of-State Vehicle 41,682 3,947,672 5.2 

 Owner-operator vehicle above 7500 miles/yr 5,056 501,599 5.1 

 Owner-operator vehicle below 7500 miles/yr 252 1,149 11.1 

 2 vehicle fleet above 7500 miles/yr 1,571 155,808 5.1 

 2 vehicle fleet below 7500 miles/yr 78 357 11.1 

 3 vehicle fleet above 7500 miles/yr 1,147 113,815 5.1 

 3 vehicle fleet below 7500 miles/yr 57 261 11.1 

 Large fleets above 7500 miles/yr 31,928 3,167,429 5.1 

 Large fleets below 7500 miles/yr 1,592 7,253 11.1 

 

Heavy-Heavy California Registered IRP Vehicle 60,263 8,282,725 5.2 

 Owner-operator vehicle above 7500 miles/yr 15,980 2,198,998 6 

 Owner-operator vehicle below 7500 miles/yr 883 5,804 10.8 

 2 vehicle fleet above 7500 miles/yr 5,850 812,823 5.8 

 2 vehicle fleet below 7500 miles/yr 318 2,096 10.9 

 3 vehicle fleet above 7500 miles/yr 3,297 460,037 5.7 

 3 vehicle fleet below 7500 miles/yr 183 1,223 11.4 

 Large fleets above 7500 miles/yr 32,273 4,791,942 4.6 

 Large fleets below 7500 miles/yr 1,479 9,801 11.3 
-61- 

Fleet Source Population VMT/day 

VMT-Weighted 

Average Age 

 

Heavy-Heavy Duty In-State Tractor 63,684 10,413,751 8.0 

 Owner-operator vehicle above 7500 miles/yr 16,792 3,031,868 10.1 

 Owner-operator vehicle below 7500 miles/yr 4,089 44,925 15.2 

 2 vehicle fleet above 7500 miles/yr 4,928 902,069 9.7 

 2 vehicle fleet below 7500 miles/yr 1,189 12,992 15.4 

 3 vehicle fleet above 7500 miles/yr 2,876 529,836 9.5 

 3 vehicle fleet below 7500 miles/yr 673 7,370 15.3 

 Large fleets above 7500 miles/yr 28,859 5,835,899 6.4 

 Large fleets below 7500 miles/yr 4,278 48,792 13.6 

 

Heavy-Heavy Single Unit In-State Vehicles 43,275 3,410,860 8.4 

 Owner-operator vehicle above 7500 miles/yr 7,819 766,081 10.3 

 Owner-operator vehicle below 7500 miles/yr 3,358 37,585 15.6 

 2 vehicle fleet above 7500 miles/yr 2,826 279,769 9.9 

 2 vehicle fleet below 7500 miles/yr 1,171 13,153 15.5 

 3 vehicle fleet above 7500 miles/yr 1,857 185,491 9.2 

 3 vehicle fleet below 7500 miles/yr 703 7,951 14.8 

 Large fleets above 7500 miles/yr 20,001 2,057,340 7.1 

 Large fleets below 7500 miles/yr 5,540 63,491 13.5 

 

Heavy-Heavy Drayage Vehicles 21,650 2,898,907 11.8 

 Serving Non-South Coast and Bay Area Facilities 1,513 236,542 9.1

 Owner-operator vehicle above 7500 miles/yr 813 127,097 9.1 

 2 vehicle fleet above 7500 miles/yr 90 14,122 9.1 

 3 vehicle fleet above 7500 miles/yr 102 15,887 9.1 

 Large fleets above 7500 miles/yr 508 79,436 9.1 

 

 Serving Bay Area Facilities 3,032 391,868 9.7

 Owner-operator vehicle above 7500 miles/yr 1,629 210,556 9.7 

 2 vehicle fleet above 7500 miles/yr 181 23,395 9.7 

 3 vehicle fleet above 7500 miles/yr 204 26,319 9.7 

 Large fleets above 7500 miles/yr 1,018 131,597 9.7 

 

 Serving South Coast Facilities 17,105 2,270,498 12.4

 Owner-operator vehicle above 7500 miles/yr 9,191 1,219,969 12.4 

 2 vehicle fleet above 7500 miles/yr 1,021 135,552 12.4 

 3 vehicle fleet above 7500 miles/yr 1,149 152,496 12.4 

 Large fleets above 7500 miles/yr 5,744 762,481 12.4 

 

Heavy-Heavy Agricultural Vehicle 11,998 878,486 11.4 

 

Non-Specialty Agricultural Vehicle Above 1st mileage 

limit (15-25k miles/yr depending on age) 4,098 645,375 10.5 

 

Non-Specialty Agricultural Vehicle Below 2nd mileage 

limit (10,000 miles/yr) 5,258 82,489 17.1 
-62- 

Fleet Source Population VMT/day 

VMT-Weighted 

Average Age 

 

Agricultural Non-Specialty Vehicle greater than 

10,000 miles/yr, less than 1st threshold 1,442 62,773 12.5 

 Agricultural Specialty Vehicle 1,200 87,849 11.4 

 

Heavy-Heavy Duty Utility Vehicle 1,357 33,801 8.2 

 

Medium-Heavy Out-of-State Vehicles 7,235 42,871 4.6 

 Owner-operator fleet above 5000 miles/yr 824 5,552 4.3 

 Owner-operator fleet below 5000 miles/yr 87 54 8.2 

 2 vehicle fleet above 5000 miles/yr 519 3,450 4.3 

 2 vehicle fleet below 5000 miles/yr 57 35 8.4 

 3 vehicle fleet above 5000 miles/yr 519 3,407 4.5 

 3 vehicle fleet below 5000 miles/yr 63 39 9.2 

 Large fleet above 5000 miles/yr 4,594 29,980 4.7 

 Large fleet below 5000 miles/yr 572 353 9.4 

 

Medium-Heavy California Registered IRP Vehicles 1,661 74,777 4.6 

 Owner-operator fleet above 5000 miles/yr 189 9,684 4.3 

 Owner-operator fleet below 5000 miles/yr 20 95 8.2 

 2 vehicle fleet above 5000 miles/yr 119 6,018 4.3 

 2 vehicle fleet below 5000 miles/yr 13 61 8.4 

 3 vehicle fleet above 5000 miles/yr 119 5,943 4.5 

 3 vehicle fleet below 5000 miles/yr 14 68 9.2 

 Large fleet above 5000 miles/yr 1,054 52,292 4.7 

 Large fleet below 5000 miles/yr 131 616 9.4 

 

Medium-Heavy California Registered In-State Vehicles 198,525 12,731,247 6.4 

 Owner-operator fleet above 5000 miles/yr 51,066 3,786,410 7 

 Owner-operator fleet below 5000 miles/yr 11,592 80,942 13.4 

 2 vehicle fleet above 5000 miles/yr 16,710 1,244,223 6.8 

 2 vehicle fleet below 5000 miles/yr 3,621 25,478 13.1 

 3 vehicle fleet above 5000 miles/yr 9,964 740,914 6.9 

 3 vehicle fleet below 5000 miles/yr 2,143 15,111 13 

 Large fleet above 5000 miles/yr 88,520 6,731,027 5.7 

 Large fleet below 5000 miles/yr 14,908 107,142 11.6 

 

Medium-Heavy Agricultural Vehicles 9,438 342,652 10.5 

 

Non-Specialty Agricultural Vehicle Above 1st mileage 

limit (15-25k miles/yr depending on age) 1,750 183,598 9.2 

 

Non-Specialty Agricultural Vehicle Below 2nd mileage 

limit (10,000 miles/yr) 4,799 46,021 16 

 

Agricultural Non-Specialty Vehicle greater than 

10,000 miles/yr, less than 1st threshold 1,946 78,768 10.3 

 Agricultural Specialty Vehicle 944 34,265 10.5 

 

Medium-Heavy Utility Vehicle 2,798 55,942 6.7 

 

School Bus 16,469 633,823 11.6 
-63- 

Fleet Source Population VMT/day 

VMT-Weighted 

Average Age 

 

Other Bus 9,974 574,946 6.7 

 

Power Take Off -- 492,322 10.2 

 

TOTAL 940,667 57,009,437 6.4 

In 2008, staff estimates that heavy-heavy duty diesel vehicles are responsible for 73.8 

percent of the population and 74.2 percent of the VMT in vehicles covered by this 

inventory. Medium-heavy duty vehicles are responsible for 23.4 percent of the 

population and 23.4 percent of the VMT, while other categories including buses are 

responsible for 2.8 percent of the population and 2.3 percent of the VMT. Within the 

heavy-heavy duty vehicle category, interstate vehicles, which include California 

registered (CA IRP) and out-of-state registered vehicles that operate inside and outside 

of California, are responsible for 59 percent of the population and 43 percent of the 

VMT, while in-state heavy-heavy duty vehicles, those vehicles which travel only within 

California, are responsible for 15 percent of the population and 31 percent of the VMT. 

These results are summarized in Table VI-3. 

Table VI-3: Percentage of Population and VMT by Vehicle Type 

Vehicle Type % of Population % of VMT 

Heavy-heavy duty vehicles (CA 

IRP and out-of-state registered) 59 43 

Heavy-heavy duty vehicles (CA 

registered) 15 31 

Medium-heavy duty vehicles 23.4 23.4 

Buses 2.8 2.3 

The age distribution of vehicles in a given calendar year has a significant impact on 

emissions estimates. For comparison purposes, it is useful to evaluate the VMTweighted average age of vehicles across inventory categories. The VMT-weighted age 

metric accounts for both the age of the vehicles in each category, and the fact that in 

most categories, newer vehicles drive more than older vehicles. The average VMTweighted age of the truck and bus fleet operating in California, including both in-state 

and out-of-state vehicles, is 6.4 years. Inventory categories that contain the highest 

fraction of vehicles in large fleets and in long haul routes, such as out-of-state and 

California registered interstate vehicles, are younger than this average. Inventory 

categories that contain the highest fraction of small fleets and do not travel outside of 

California are older than average. Within given inventory categories, vehicles and fleets 

that accrue more mileage per year tend to be newer, while vehicles accruing less 

mileage per year are older. On average, small fleets are older than large fleets. 
-64- 

3. Mileage Thresholds 

Once VMT was calculated, staff estimated the proportion of total VMT that was above 

and below mileage thresholds relevant to the regulation. To calculate this, ARB staff 

started with data from Vehicle Inventory and Use Survey (VIUS) 2002 and/or other 

surveys used to develop mileage accrual schedules for each category. Staff sorted 

data from lowest to highest mileage by model year and inventory category. Each 

mileage threshold was then assessed; for example to estimate the 7,500 mileage 

threshold in each category the total population of vehicles in the accrual data was 

calculated, as was the population of vehicles reporting miles above and below the 

threshold. At the same time, staff estimated the total accrued mileage for all vehicles in 

the category, as well as for vehicles above and below the 7,500 mile threshold. The 

result was a statistic for each category that indicated the percentage of population and 

VMT in the category that is estimated to represent vehicles in fleets below the assessed 

mileage threshold. 

Table VI-4 provides the percent of population and VMT below the mileage thresholds, 

by inventory category, in 2008. For this analysis, staff assumed the fraction of 

population and mileage below the mileage threshold was not impacted by fleet size. 

Table VI-4: Distribution of Population and VMT by Mileage Threshold (2008) 

Type / Category Mileage 

Threshold 

Percent of VMT 

Below Mileage 

Threshold 

Percent of Population 

Below Mileage 

Threshold 

Heavy-Heavy / Out-of-State 7,500 0.1% 2.7% 

Heavy-Heavy / CaliforniaInterstate 7,500 0.2% 4.8% 

Heavy-Heavy / In-state Tractor 7,500 1.1% 16.1% 

Heavy-Heavy / In-state Single 7,500 3.6% 24.9% 

Heavy-Heavy / Drayage Tractors 7,500 0% 0% 

Heavy-Heavy / Agricultural 15/20/25* 16.5% 55.8%

Vehicles 10,000 9.4% 43.8% 

Medium-Heavy / In-state Vehicles 5,000 1.8% 16.3% 

Medium-Heavy / Interstate 

Vehicles 5,000 1.1% 10.8% 

Medium-Heavy / Agricultural 15/20/25* 36.4% 71.5% 

Vehicles 10,000 13.4% 50.8% 

* 15,000 miles/yr would apply to pre-1996 model year vehicles; 20,000 miles/yr would apply to 1996-2005 model year 

vehicles; and 25,000 miles/yr would apply to 2006 and newer model year vehicles. 

4. Fraction of Mileage Accrual in California 

Out-of-state vehicles operating in California drive only a portion of their miles in 

California. Staff analyzed IRP data from 12 states (Alabama, Arizona, Idaho, Indiana, 

Nebraska, New Jersey, Nevada, Oklahoma, Oregon, Texas, and Wisconsin) to assess 

the fraction of miles traveled in California from out-of-state vehicles. Staff then 

compared this to International Fuel Tax Agreement (IFTA) data which provided 

estimates for the total miles traveled in 2005, 2006, and 2007 for vehicles registered in 

each of the fifty states and eight Canadian jurisdictions that are a party to that program. 
-65- 

Estimates of the fraction of out-of-state vehicle VMT that is accrued in California in 2008 

are shown in Table VI-5. 

Table VI-5: Fraction of Miles Traveled in California for Out-of-State Categories 

Type / Category Fraction of Mileage Accrued in California

Heavy-Heavy / Non-Neighboring Out-of-State 9.9% 

Heavy-Heavy / Neighboring Out-of-State 39.3% 

Heavy-Heavy / CA IRP 57.0% 

Medium-Heavy / Interstate Vehicles 18.7% 

5. Forecasting Population and VMT 

In order to forecast emissions in the future, staff assessed growth in population and 

VMT. Staff started by comparing growth rates embedded in EMFAC2007. Those 

growth rates are composited from individual estimates made by regional transportation 

planning agencies and provide a statewide growth heavy-duty vehicle VMT growth rate 

of approximately 2 percent per year. Staff found this statewide average growth rate to 

be consistent with the historical national growth in transportation related gross domestic 

product through 2006, as shown in Figure VI-1. The growth rates developed by 

transportation agencies are designed to represent average growth over long periods of 

time and are not designed to forecast periods of economic growth or recession. 
-66- 

Figure VI-1: The Historic and Projected Relationship between VMT and GDP on a 

Nationwide Level 

0

50,000

100,000

150,000

200,000

250,000

1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025

VMT (Millions)

Observed truck miles, combination Nationwide projected truck miles

VMT ~ 48,000 + 900*Trucking GDP

where GDP is in $billions

 VMT is in millions

Since the beginning of 2007, the price of diesel fuel has increased dramatically, and the 

state as well as the national economy has slowed. Diesel fuel prices can have a major 

impact on driving patterns, and freight transportation choices between trucks and rail, 

especially for longer haul and non-perishable commodities. Staff does not yet have 

sufficient data to determine what the impact of the current fuel price spike has been on 

statewide vehicle VMT, and staff is continuing to evaluate the issue to determine if 

future growth rate projections should be refined. Until that work is completed, staff is 

continuing to rely on historical growth trends that are consistent with regional growth 

estimates developed by regional transportation planning agencies. 

Typically, mobile source emissions inventory models, including EMFAC, estimate 

attrition (the number of vehicles dropping out of the fleet) as part of applying growth. 

Consistent with EMFAC, this inventory includes vehicles up to age 44 in any given 

calendar year. This means that in 2008, 1964 is the oldest vehicle model year in the 

inventory. Under typical attrition algorithms, the population of vehicles 44 years old 

would be removed from the inventory each year, and that population of older vehicles 

would be replaced by an equivalent number of new vehicle sales. However, through 

our analysis of vehicle populations for this inventory, staff realized that tractors are 

typically sold new to national fleets, operated for several years, and then sold to 

regional fleets. This results in a larger increase in the number of older vehicles in the 

population of in-state tractors than would be predicted by the traditional attrition 

algorithms. To correct this, staff used a simplified approach of holding model year 

distributions constant over time. 
-67- 

In addition to general economic growth, the implementation of new emission standards 

can have a significant impact on new vehicle purchase rates, and therefore penetration 

of different vehicle model years into the statewide vehicle population. To evaluate how 

emissions standards impact vehicle sales, staff developed a model that accounts for the 

relationship between economic growth and national vehicle sales, as well as the 

relationship between vehicle sales and the penetration of new emissions standards. To 

accomplish this task, staff first developed a historical regression model between 

national heavy-heavy duty vehicle sales and economic trends (as measured by national 

trucking industry gross domestic product). The results from this model are shown in 

Figure VI-2 where actual heavy-heavy duty diesel vehicle sales from 1985-2007 (solid 

line) are plotted against the economic regression model (dotted line) over the same 

period. Results show that economic trends explain a substantial amount of the 

historical variability in vehicle sales. 

Figure VI-2: Estimated Future New Vehicle Sales by Calendar Year 

0

50,000

100,000

150,000

200,000

250,000

300,000

1985 1990 1995 2000 2005 2010 2015 2020

Truck Sales

Actual 

truck 

sales

Originally predicted 

truck sales

Predicted truck 

sales after first 

adjustment

Predicted truck 

sales after 

second 

adjustment

Next, staff projected economic growth into the future and applied staff’s regression 

model to estimate future vehicle sales without any impact from emissions standards. 

This is represented as a “first adjustment” on the chart. Staff then extrapolated 2008 

vehicle sales based on sales through June 2008, and found that staff’s model was over 

estimating 2008 sales, likely due to both an over estimate of future economic 

performance and pre-buy trends. Most economic indicators used in this model do not 

reflect the very latest economic conditions. To adjust the regression model for the likely 

short term over estimate of economic performance, as well as pre-buy trends, staff 

assumed the same differential between the 2002-2004 model year results and sales 
-68- 

would also apply to the 2008-2009 model years. When actual sales data for the first 

half of 2008 was obtained by staff, the predicted vehicle sales for the entirety of 2008 

decreased. Because of the projected significant decrease in demand for vehicles in 

calendar years 2007 through 2009, and the expected fuel economy benefit of 2010 

standard compliant vehicles (as described in section D), staff assumed steady growth in 

vehicle sales from 2009 through 2016, at which point sales are assumed to revert to 

historical average trends. This is shown in Table VI-2 as a “second adjustment”. 

C. Emissions Rates 

Estimating emissions requires the use of an emission factor, which relates the number 

of miles traveled by a vehicle to that vehicle’s emissions on a per mile basis. Emission 

rates are a function of engine size, vehicle size, technology, driving conditions, speed, 

load, loaded weight, temperature, relative humidity, and many other factors. Emission 

rates deteriorate, which reflects an increase in emission rates over time as the engine 

and vehicle ages. Deterioration in diesel engines is modeled as a function of tampering, 

malmaintenance, and malfunction of various engine components. 

To develop emission rates used in this inventory, staff used the EMFAC model. 

EMFAC2007 contained a number of significant improvements to heavy-heavy duty 

diesel vehicle emission rates, including updated base emission rates developed from 

recent academic studies (Coordinating Research Council (CRC), 2007) and revisions to 

assumptions behind tampering, malmaintenance, and malfunction of engine 

components. Staff then made a number of significant adjustments to emission rates 

which are described briefly here; more information is available in the emissions 

inventory technical discussion in Appendix G. 

1. Medium-Heavy Duty Diesel Vehicle Emission Rates 

Staff used test results from the CRC E55/59 test program to update medium-heavy duty 

diesel vehicle running emission rates and speed correction factors. Staff used the same 

analysis method as developed for the heavy-heavy duty diesel vehicle update 

integrated into EMFAC2007. The integration of these updated emission rates led to 

slight changes in NOx and PM2.5 emissions which varied by calendar year. 

2. Banking Provisions in Emissions Standards 

Staff evaluated the penetration of diesel particulate filter (DPF) equipped 2007 model 

year vehicles, and the model years in which the new technology was sold. This led to 

negligible changes in emission rates for the 2006-2009 model year engine emission 

factors. Staff also estimated the expected penetration of the cleanest 2010 compliant 

engines in 2010-2012 based on multiple discussions with engine manufacturers and 

review of their public statements. Overall, based on the latest information, staff found 

that because selective catalytic reduction (SCR) technology (used to meet NOx

emission standards in 2010 compliant engines) provides a fuel economy benefit relative 

to previous technologies, the vast majority of 2010 model year engines will be equipped 

with SCR. 
-69- 

3. Carbon Dioxide Emission Rates 

Staff conducted a thorough review of CO2 emission rates based on test data in the CRC 

E55/59 program, U.S. Department of Energy (U.S. DOE) annual fuel economy data, 

IFTA data, and West Virginia University In-Use Consent Decree data. Staff analyzed 

fuel economy data due to the limited CO2 dataset for heavy-duty vehicles and converted 

the results into CO2 emissions rates based on fuel carbon content. Results indicate 

vehicles driving in California have slightly higher average fuel economy (~5.7 miles per 

gallon (mpg)) and therefore lower CO2 emissions relative to what is assumed in 

EMFAC2007 (5.4 mpg). Staff found that fuel economy does vary on average across 

model years, with the highest fuel economy in 2010 standard compliant engines. Staff 

assumed a 3 percent fuel economy penalty associated with 2007 standard vehicles due 

to increased back-pressure on the engine caused by the DPF and use of exhaust gas 

recirculation (EGR) technology. Staff assumes a 2 percent fuel economy penalty 

associated with retrofit diesel particulate filters. Staff assumes a 4 percent fuel 

economy benefit in the 2010 emission standard vehicles due to better engine mapping 

for fuel efficiency coupled, with the SCR. These assumptions regarding fuel economy 

affect the assumption of CO2 emissions. 

D. Statewide Baseline Emissions Estimates 

Staff estimated trucks and buses included in the inventory in 2008 will emit 859 tons of 

NOx on an average annual day, 33 tons per day of PM2.5, and 108,000 tons of CO2 on 

an average annual day, as shown in Table VI-6. About 40 percent of the statewide 

annual average NOx and PM2.5 emissions from on-road vehicles are generated by 

interstate vehicles, while vehicles that operate only within California generate the 

remaining 60 percent of statewide NOx and PM2.5 emissions. 
-70- 

Table VI-6: Statewide Emissions by Truck and Bus Inventory Category (2008) 

CY Inventory 

Category 

Vehicle 

Population

Vehicle CA 

VMT/day 

NOx 

(tons/day) 

PM2.5 

(tons/day) 

CO2

(tons/day) 

2008 HH Out-of-State 492,340 16,142,326 221.9 8.0 32,766 

2008 HH CA IRP 60,263 8,282,725 139.6 5.2 16,783 

2008 HH Tractor 63,684 10,413,751 194.1 7.9 20,897 

2008 HH Single Unit 43,275 3,410,860 57.8 1.9 6,876

2008 HH Drayage 21,650 2,898,907 70.0 3.2 6,006 

2008 HH Agriculture 11,998 878,486 17.3 0.7 1,788 

2008 HH Utility 1,357 33,801 1 0 79 

2008 MH In-state 198,525 12,731,247 125.0 4.6 19,067 

2008 MH Interstate 8,896 117,648 1.0 0.0 176 

2008 MH Agriculture 9,438 342,652 4.0 0.2 521 

2008 MH Utility 2,798 55,942 1 0 85 

2008 Buses 26,443 1,208,769 15.0 0.4 2,036 

2008 PTO 0 492,322 12.2 0.8 1,349 

2008 All 940,667 57,009,437 859.3 33.1 108,429 

Table VI-7 shows statewide truck and buses emissions by fleet size and mileage 

threshold for calendar year 2008. Results show that small fleets (those with three or 

fewer vehicles) are responsible for roughly 36 percent of NOx and PM2.5 emissions, 

while large fleets (four or more vehicles) are responsible for 64 percent of baseline 

emissions in 2008. Results also show that while low mileage vehicles represent roughly 

8 percent of the vehicles, they contribute only 0.9 percent of vehicle miles traveled and 

less than 2 percent of emissions. 
-71- 

Table VI-7: Baseline Emissions by Fleet Size and Mileage Threshold (2008) 

CY Fleet Size Vehicle 

Population 

Vehicle 

CA 

VMT/day 

NOx 

tpd 

PM2.5 

tpd 

CO2 

 tpd 

2008 1 vehicle/above threshold 116,314 12,050,689 209.5 8.26 22,460 

2008 1 vehicle/below threshold 20,462 170,742 3.4 0.17 331 

2008 2 vehicle/above threshold 35,941 3,636,157 59.0 2.30 6,701 

2008 2 vehicle/below threshold 6,502 54,229 1.1 0.05 105 

2008 3 vehicle/above threshold 22,739 2,275,887 37.2 1.46 4,215 

2008 3 vehicle/below threshold 3,876 32,062 0.6 0.03 62 

2008 4+ vehicle/above threshold 643,202 35,528,640 493.5 18.36 68,191 

2008 4+ vehicle/below threshold 39,598 249,058 5.0 0.22 505 

2008 Ag non specialty higher VMT 5,848 828,973 14.5 0.58 1,579 

2008 Ag non specialty lower VMT 10,057 128,510 2.6 0.14 251 

2008 Ag non specialty midrange VMT 3,388 141,541 2.2 0.10 248 

2008 Ag specialty vehicle 2,144 122,114 2.1 0.09 231 

2008 Unspecified 30,597 1,790,835 28.5 1.30 3,549 

2008 All 940,667 57,009,437 859.3 33.07 108,429 

Figure VI-3, Figure VI-4 and Figure VI-5 show baseline emissions forecasted to 2023 for 

NOx, PM2.5, and CO2, respectively. Results show that while CO2 emissions are 

expected to increase over time, NOx and PM2.5 emissions are projected to decrease as 

new vehicles equipped with the latest emission control technologies enter the fleet due 

to natural replacement, and as previously adopted rules are implemented. Even though 

emissions are decreasing, staff estimates suggest that in the absence of the proposed 

regulation it would take several decades for all vehicles operating in California to meet 

the 2010 emissions standard through natural replacement alone. The proposed 

regulation is necessary to reduce emissions to levels that would ensure attainment with 

federal ozone and PM2.5 ambient air quality standards. A summary of PM and NOx 

emissions baseline is shown summarized below in Table VI-8. 

 

Table VI-8: Statewide PM and NOx Baseline Emissions

Calendar Emissions (ton per day) 

Year PM Baseline NOx Baseline 

2010 27.8 749 

2014 19.0 500 

2017 14.4 401 

2020 12.1 346 

2023 10.5 319 
-72- 

Figure VI-3: California Statewide NOx Emissions from Trucks, Baseline 2008-2023 

0

100

200

300

400

500

600

700

800

900

1,000

200720082009201020112012201320142015201620172018201920202021202220232024

NOx emissions (tons/day)

Figure VI-4: California Statewide PM2.5 Emissions from Trucks, Baseline 2008-

2023 

0

5

10

15

20

25

30

35

200720082009201020112012201320142015201620172018201920202021202220232024

PM2.5 emissions (tons/day)
-73- 

Figure VI-5: California Statewide CO2 Emissions from Trucks, Baseline 2008-2023 

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

200720082009201020112012201320142015201620172018201920202021202220232024

CO2 emissions (tons/day)

E. Updating EMFAC with this New Analysis 

It is important to emphasize that any emissions inventory is our best assessment of 

emissions based on what is known today. This assessment necessarily evolves over 

time. The ARB maintains an on-road emissions inventory model, called EMFAC, which 

provides official emissions inventory estimates that are used for planning and SIP 

purposes. The most recent version of this model, EMFAC2007, was released in early 

2007 to support development of the ARB’s statewide and regional air quality attainment 

plans. Since the release of EMFAC2007, staff has developed an expanded approach to 

assess vehicle operations in California that greatly enhances their ability to understand 

operations of different vehicle categories in California. Whereas EMFAC2007 

separated heavy-duty vehicle operations only by weight and fuel, the emissions 

inventory developed for this proposed regulation separates trucks and buses into 

categories based on weight, fuel, body type, registration status, and in some cases 

vocation. This work is the culmination of several years of evaluation as a result of 

regulatory development and research. 

Because EMFAC is ARB’s official on-road emissions inventory model, staff is working 

towards integrating the new inventory developed for this regulation into the model. One 

of the most critical questions that must be answered when integrating this new inventory 

into EMFAC is spatial allocation, which is the distribution of statewide emissions into air 

basins and air districts. The assessment of engine emissions on a regional level is 

important for assessing regional compliance with air quality standards. To develop an 

improved assessment of regional vehicle travel staff is conducting a field study focusing 

on more than 60 locations throughout California. To date, this study has generated 
-74- 

more than 6,000 origin-destination surveys and 120,000 pictures of vehicle license 

plates. Staff is currently in the process of evaluating the data, and while preliminary 

regional emissions estimates were presented in public workshops in July 2008, staff 

believes more work is necessary to develop and evaluate regional activity and 

emissions estimates. Over the next year staff will be working with regional 

transportation and air quality agencies to evaluate regional activity and emissions 

estimates. Staff intends to complete this in 2009 as part of the EMFAC update process, 

and release an updated version of EMFAC in the 2010 timeframe. 

F. References 

Coordinating Research Council, Inc., 2007. Heavy-Duty Vehicle Chassis Dynamometer 

Testing for Emissions Inventory, Air Quality Modeling, Source Apportionment and Air 

Toxics Emissions Inventory. August 2007. Available at: 

http://www.crcao.com/reports/recentstudies2007/E-55-59/E55_59_Final_Report_23AUG2007.pdf 

National 2002 VIUS. U.S. Census Bureau 2002 Economic Census: Vehicle Inventory 

and Use Survey. EC2TV-US. Issued December 2004 
-75- 

VII. ON-ROAD DIESEL RETROFIT TECHNOLOGY

The proposed regulation would require in-use on-road diesel fleets to install verified 

DECS and to accelerate replacement of existing vehicles to those with a engines 

meeting the 2010 MY engine emission standards. This chapter discusses retrofit 

strategies potentially available for reducing diesel emissions from in-use on-road diesel 

vehicles. 

A. Diesel Emission Control Strategies 

Reducing emissions from diesel engines is an area of active research and development. 

While on-road diesel engine manufacturers are optimizing technologies to reduce PM 

and NOx emissions to meet future California and federal new engine exhaust 

standards, the fields of retrofitting with exhaust aftertreatment devices and engine 

repowering are also growing rapidly. This activity is spurred both by the ongoing 

research and development for new engines, and by California’s control measures for inuse diesel fleets. 

1. Exhaust Retrofits 

A variety of retrofit strategies can be used for controlling emissions from in-use diesel 

engines (Diesel Forum, 2006). The main types of technologies discussed here are addon hardware, additives, combinations of hardware and additives, and NOx control. The 

hardware retrofit technologies that are most likely to be employed, i.e., diesel particulate 

filters (DPFs) and flow through filters (FTFs), are retrofitted onto the exhaust pipes 

downstream of the engine. Additive based systems reduce emissions by introducing an 

additive, typically precious metal, into the fuel, air intake, or exhaust system, depending 

on the type of additive employed. Combinations of hardware and additives could 

include a device retrofitted to the exhaust system and an additive introduced into the 

fuel stream. The most common NOx control systems use open channel catalysts 

together with a chemical reductant (usually urea or diesel fuel) that is injected into the 

exhaust stream. These technologies are discussed in more detail below. 

Technical suitability of a particular type of DECS will depend on the engine and vehicle 

to be retrofit. Technical considerations include space constraints inside the engine 

compartment, operator visibility, weight of the DECS, vibration, backpressure, exhaust 

temperatures, and safety. For instance, for very large engines, two devices in parallel 

(dual) may be required to avoid excessive backpressure and allow sufficient exhaust 

flow. 

a) Hardware Diesel Emission Control Strategies 

There are a number of hardware diesel emission control strategies available to reduce 

diesel PM emissions from in-use diesel vehicles, including DPFs and FTFs. Some 

DPFs also reduce CO and HC emissions through catalytic oxidation and filtration. Most 

DPFs sold in the United States use substrates consisting either of a ceramic wall flow 

filter or a silicon carbide substrate. These substrates are either coated with a catalyst 

material, typically a platinum group metal, or a separate catalyst that is installed 
-76- 

upstream of the particulate filter. The filter is positioned in the exhaust stream to trap or 

collect a significant fraction of the particulate emissions while allowing the exhaust 

gases to pass through the system. 

Effective operation of a DPF requires a balance between PM collection and PM 

oxidation, or regeneration. The volume of PM generated by a diesel engine will fill up 

(load) a DPF over time; thus the trapped PM must be burned off or "regenerated" 

periodically. Regeneration is accomplished by either raising the exhaust gas 

temperature or by lowering the PM ignition temperature through the use of a catalyst. In 

contrast, FTFs employ a catalyzed wire mesh substrate that has an intermix of flow 

channels creating turbulent flow conditions. 

(1) Passive Diesel Particulate Filter (Passive DPF)

A passive DPF is one in which a catalytic material, typically a platinum group metal, is 

applied to the filter itself or some other substrate upstream of the filter. The catalyst 

lowers the temperature at which trapped PM will oxidize to levels that are often reached 

in diesel exhaust, generally 250 to 400 degrees Celsius (oC), depending on the vehicle’s 

duty cycle. No additional source of energy is required for regeneration, hence the term 

“passive”. Most verified passive DPFs require exhaust temperatures of at least 225 to 

280 oC for about 25 to 50 percent of the vehicle’s duty cycle. Verified passive DPFs 

have demonstrated reductions of at least 85 percent for PM, and are verified as Level 3 

devices. A passive catalyzed DPF also reduces CO and HC by approximately the same 

amount as the PM reduction. A passive catalyzed DPF (See Figure VII-1) is an 

attractive means of reducing diesel PM emissions on certain engines and duty cycles 

because of the combination of high reductions in PM emissions and minimal operation 

and maintenance requirements. 

Figure VII-1: Wall Flow Filter 

The following passive devices have been verified through ARB’s verification procedure 

and include devices that also meet the 2009 NO2 limits as designed with the “+” symbol. 

All of these devices achieve a least an 85 percent reduction in PM emissions and are 
-77- 

therefore designed as Level 3 devices. Each device is certified to operate on certain 

engine families as listed in the Executive Order. These devices are described below in 

Table VII-1. 

Table VII-1: Passive DPF 

Product Name Technology Type 

P

L

U

S

PM 

Reduction 

NOx 

Reduction Applicability 

Cleaire Longview Wall Flow Lean NOx 

Catalyst and DPF 85% 25% Most 1993-2006 model year on-road engines 

Donaldson DPM Wall Flow DPF 85% N/A. Most 1993-2006 model year 

on-road engines 

Engine Control System 

Purifilter Wall Flow DPF + 85% N/A Most 1993-2006 model year on-road engines 

International Truck and 

Engine Corporation DPX Wall Flow DPF 85% N/A. Most 1994-2003 model year on-road Navistar engines 

Johnson Matthey EGRT Wall Flow EGR/DPF + 85% 40%

Most 1998-2001 model year 

International, Cummins and 

DDC on-road engines 

Johnson Matthey CRT Wall Flow DFF 85% NA Most 1994-2006 model year 

on-road engines 

(2) Active Diesel Particulate Filter (Active DPF) 

Unlike passive DPFs, active DPFs use a source of energy for regeneration beyond the 

heat in the exhaust stream itself. Active DPF systems can be regenerated electrically, 

with fuel burners, or with the aid of additional fuel injection to increase exhaust gas 

temperature. Some active DPFs induce regeneration automatically on-board the 

vehicle when a specified backpressure is reached. Others simply indicate to the 

operator when regeneration is needed, and require the operator to initiate the 

regeneration process. Some active systems collect and store diesel PM over the 

course of a full day or shift and are regenerated at the end of the day with the vehicle or 

equipment shut off. The time between regeneration can range from a single, 8 hour 

shift to several weeks depending on a number of factors. Some systems are designed 

such that the filters can be removed and regenerated externally at a “regeneration 

station”. 

For applications in which the engine-out PM is relatively high, and/or the exhaust 

temperature is relatively cool, actively regenerating systems are more effective than a 

passive DPF. Because active DPFs are not dependent on the heat carried in the 

exhaust for regeneration, they potentially have a broader range of application than 

passive DPFs, and passive DPFs have more flexibility on where, they are installed 

since they are not required to be close to the engine. 

Two active systems have been verified through ARB’s verification procedure. The 

Cleaire Horizon uses electricity, through an integrated heating element, to heat up and 

burn off the collected PM while the vehicle is parked overnight. The HUSS MK-
-78- 

SYSTEM used a small diesel burner to heat up the DPF and burn off the collected PM 

while the engine is off. This process, known as regeneration, can take anywhere from a 

few minutes to over a half and hour. These devices are described below in Table VII-2. 

Table VII-2: Wall Flow Filter 

Product Name Technology Type 

P

L

U

S

PM 

Reduction 

NOx 

Reduction Applicability 

Cleaire Horizon Wall Flow DPF + 85% N/A Most on-road engines 

HUSS 

Umwelttechnik 

FS_MK 

Wall Flow DPF + 85% N/A Most on-road engines 

(3) Catalyzed Wire Mesh Flow Through Filter 

FTF technology is a form of aftertreatment that achieves PM reductions less than that of 

a DPF. There are several different FTF designs, but they tend to share the 

characteristic that they do not trap and accumulate PM like a DPF. Instead, FTF (See 

Figure VII-2) have a medium (such as a wire mesh) that forces the exhaust into a 

complex flow pattern that gives rise to turbulent flow conditions, or in some cases a 

partial trapping of PM. The medium is typically treated with an oxidizing catalyst that is 

able to reduce emissions of PM, HC, and CO. The particles that are not oxidized within 

the FTF flow out with the rest of the exhaust and tend not to accumulate. FTF 

performance can be highly variable and sensitive to exhaust temperature, but is 

normally consistent with a 25-50 percent reduction in PM emissions. 
-79- 

Figure VII-2: Flow Through Filter 

There is only one device that uses the flow through technology that has been verified 

through ARB’s verification process. The Donaldson DPM uses a multi-stage passive 

flow through filter incorporated in a muffler unit to achieve 50 percent reduction of 

particulate matter. This device is shown below in Table VII-3. 

Table VII-3: Active DPF 

Product Name Technology Type 

P

L

U

S

PM 

Reduction 

NOx 

Reduction Applicability 

Donaldson DPM Flow Through Filter + 50% N/A 

Most 1991-2002 model 

year on-road; CARB 

diesel; biodiesel. 

b) Additive Diesel Emission Control Strategies 

Additive DECS utilize a substance, other than diesel fuel, which is added during the 

operation of the vehicle, either pre-combustion or post-combustion, to reduce diesel 

exhaust emissions. Pre-combustion additives include fuel based and intake air based 

additives that utilize the fueling system or air intake systems, respectively, to introduce 

an additive. Post-combustion additives include exhaust based additives that introduce 

an additive directly into the exhaust system to reduce exhaust emissions. Most additive 

systems are designed to work in conjunction with a hardware component and are often 
-80- 

offered as a combined hardware and additive system as discussed in the next 

subsection. 

Additive DECS must undergo an assessment of multimedia toxicity effects by the 

California Environmental Policy Council, as required by HSC section 43830.8 prior to 

ARB verification. 

(1) Fuel-Water Emulsion 

Alternative diesel fuel is a fuel that can be used in a diesel engine without modification 

to the engine and that is not a reformulated diesel fuel. For example, alternative diesel 

fuels may include emulsified fuels, biodiesel fuels, Fischer Tropsch fuels, or a 

combination of these fuels with regular diesel fuel. The emissions effects of these fuels 

can vary widely. 

Fuel-water emulsion, a demonstrated alternative to diesel fuel that reduces both PM 

and NOx emissions is an emulsion of diesel fuel and water. The process blends water 

into diesel fuel, along with an emulsion additive to keep the mixture from separating. 

The water is suspended in droplets within the fuel, creating a cooling effect on the fuel 

that decreases NOx emissions. Also, a fuel-water emulsion creates a leaner fuel 

environment in the engine, thus lowering PM emissions as well (U.S. EPA, 2002). 

PuriNOx, produced by Lubrizol, is a low emission diesel fuel system comprised of 

commercial diesel fuel, water, and additives. It has been verified by ARB to reduce 

NOx emissions by 15 percent and PM emissions up to 50 percent. PuriNOx can be 

used in any older or newer diesel engines without modification to fuel systems or engine 

hardware. It is be blended in the field using portable and automated PuriNOx blending 

units that combines the PuriNOx additive package, water, diesel fuel and, when 

necessary, seasonal components like freeze depressants. This product is described 

below in Table VII-4. 

Table VII-4: Fuel-Water Emulsion 

Product Name Technology Type 

P

L

U

S

PM 

Reduction 

NOx 

Reduction Applicability 

Lubrizol PuriNOx Emulsified Fuel + 50% 15% 1988-2003 on-road

(2) Fuel Additives 

A fuel additive, such as a fuel-borne catalyst, is a substance designed to be added to 

fuel or fuel system so that it is present in cylinder during combustion and its addition 

causes a reduction in exhaust emissions. Additives can reduce the total mass of PM, 

with variable effects on carbon monoxide, NOx, and gaseous hydrocarbon production. 

The range of PM reductions that have been published in studies of fuel additives is from 

15 to 50 percent reduction in mass. Most additives are fairly insensitive to fuel sulfur 

content and will work with a range of sulfur concentrations as well as different fuels and 

other fuel additives (ARB, 2003). No fuel additive is currently verified by ARB. 
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c) Combinations of Hardware and Additive Diesel Emission Controls 

Devices 

While not currently verified in California, systems combining hardware and an additive 

strategy are used in other parts of the world. In order to receive ARB verification, the 

hardware and additive strategy must be approved together as a system. 

(1) Fuel-Borne Catalyst (FBC) 

A fuel-borne catalyst (FBC) is a substance that is added to diesel fuel in order to aid in 

soot oxidation in DPFs by decreasing the ignition temperature of solid carbon. An FBC 

can be used in conjunction with both passive and active filter systems to aid system 

performance, and decrease mass PM emissions. FBC/DPF systems are in widespread 

use in Europe in on-road, mobile and stationary applications, and typically achieve a 

minimum of 85 percent reduction in PM emissions. The ARB has not verified any 

system using an FBC as of October 2008. 

d) NOx Control Strategies 

Although not as mature as PM control strategies in general, significant research into 

NOx control strategies that may be suitable for retrofit use is being conducted and a 

number of NOx control strategies for diesel engines are nearing commercial readiness. 

(1) Exhaust Gas Recirculation (EGR) 

EGR is an effective engine control method for reducing NOx emissions that has been 

used in many new engine applications for the past five years. A valve connected to the 

exhaust system allows a controlled portion of spent combustion gases to circulate back 

into the intake system where it mixes with precombustion air. The exhaust serves as a 

diluent to lower the in cylinder oxygen concentration and also to increase the heat 

capacity of the air/fuel mixture. This reduces peak combustion temperature and the rate 

of combustion, thus reducing NOx emissions. Though much less prevalent than EGR 

systems for new engines, EGR retrofits are in use both in Europe and in the United 

States. One such system which is combined with a passive DPF is currently verified for 

certain on-road engines in California. Typical NOx reductions achieved by EGR retrofits 

are about 40 to 50 percent. 

The Johnson Matthey EGRT emission control system combines their CRT® system with 

EGR technology. Engine exhaust flows through a 2-stage CRT diesel particulate filter to 

reduce CO, PM, and HC. The EGR system re-circulates cooled, particulate-free 

exhaust back into the engine intake – resulting in a significant NOx reduction with no 

efficiency loss in the engine. 

(2) Lean-NOx Catalyst Systems 

Another aftertreatment-based NOx control technology is referred to as a lean-NOx 

catalyst (LNC). Similar in principle to an SCR system, an LNC system relies on 

injection of a reductant, typically diesel fuel, upstream of the catalyst to reduce NOx 
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emissions. The NOx reductions achievable by LNC technology are sensitive to the 

exhaust temperature and type of hydrocarbon used, but is typically in the neighborhood 

of 20 to 30 percent. 

The Cleaire Longview integrates a NOx reduction catalyst and catalyzed wall flow 

silicon carbide DPF to provide simultaneous reduction of NOx, PM, HC, and CO. The 

Longview system monitors various parameters and controls the amount NOx reductant 

injected into the system to achieve a verified 25 percent reduction of NOx emissions 

(See Figure VII-3). 

Figure VII-3: Cleaire Longview Lean-NOx Catalyst System 

(3) Selective Catalytic Reduction (SCR) 

SCR systems are just now emerging as a retrofit option in the United States and are 

expected to be widely used to meet U.S. EPA new on-road engine standards starting in 

2010. SCR systems are a form of aftertreatment technology that uses a reductant, 

typically urea, to convert NOx to nitrogen and oxygen over a catalyst. A precise amount 

of reductant is injected into the exhaust upstream of the catalyst. If the reductant is well 

mixed with the exhaust and the exhaust temperature is adequate, (typically between 

250 and 450oC) an SCR system can achieve NOx reductions on the order of 50 to 90 

percent. SCR technology is already mature in stationary applications, and is beginning 

to emerge as a NOx control solution for in-use mobile sources. One of the challenges 

facing SCR technology is the practical need to ensure that the end-user maintains a 

continuous supply of reductant. Urea, as reductant, is currently is not as commercially 

available as diesel fuel. However, with the anticipated widespread introduction of SCR 

in new 2010 and later diesel engines, staff expects that urea availability will quickly 

expand. Also, if urea is not present in the SCR unit, it will not cause any intrinsic engine 

or vehicle operational problems. 
-83- 

Although not as widely applicable as DPFs, SCR systems may be suitable for certain 

retrofit applications, and a number of demonstration programs in California and across 

the country are underway. A discussion of SCR demonstration programs currently 

underway is provided later in this chapter. 

Despite the potentially significant NOx reductions SCR can provide, exhaust 

temperatures (or duty cycle limitations) will likely dictate the actual suitability of certain 

vehicles to use SCR or other NOx control technologies in exhaust retrofit applications. 

In general, SCR systems need to operate in temperature ranges similar to those 

required for passive DPF systems. No level 2 or 3 systems in conjunction with SCR are 

currently verified. 

Johnson Matthey has developed a 4-Way emission control technology system called 

the SCRT, which reduces NOx by 70-90 percent and PM by over 90 percent (See 

Figure VII-4). It also reduces CO and HC. The urea based SCR technology is 

combined with Johnson Matthey’s 2-stage CRT® particulate filter system where the 

engine exhaust flows through to reduce CO, PM, and HC. A controlled amount of urea 

is then injected into the exhaust before it enters the SCR catalyst bed providing the 

necessary chemical conditions for the SCR catalyst to reduce NOx. 

Figure VII-4: Johnson Matthey SCRT System 

B. Verification of Diesel Emission Control Strategies 

1. ARB’s Diesel Emission Control Strategies Verification Program 

ARB’s verification program evaluates the applicability, durability, and effectiveness of 

PM and NOx control technology. Verification is an approval from ARB which assures 

end users that a verified retrofit device achieves its advertised emission reductions and 

is durable (based on in-use field testing). ARB adopted a procedure to verify DECS in 

2003 (title 13, CCR, sections 2700 et seq.). A DECS is a device that is installed onto an 

in-use engine to reduce emissions for that engine, is not part of the new engine 
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certification program, and is not covered through the new engine or emission warranty 

from the engine manufacturer. The purpose of the verification procedure is to verify 

strategies and systems that reduce diesel PM and/or NOx emissions from in-use 

engines. Under the verification program, the device manufacturer is required to provide 

a warranty against engine damage caused by the DECS. The minimum warranty period 

for on-road devices is listed in Table VII-5. To protect the end user, only ARB verified 

DECS can be used in all of ARB’s mandated and most of its voluntary retrofit programs. 

Table VII-5: Diesel Emission Control Strategy Warranty Period 

Engine Size Minimum Warranty 

Period 

Light-heavy-duty, 70 to 170 hp, GVWR less 

than 19,500 lbs. 5 years or 60,000 miles 

Medium-heavy duty, 170 to 250 hp, GVWR 

from 19,500 lbs. to 33,000 lbs. 5 years or 100,000 miles 

Heavy-heavy duty, exceeds 250 hp, GVWR 

exceeds 33,000 lbs. 5 years or 150,000 miles 

Heavy-heavy duty, exceeds 250 hp, GVWR 

exceeds 33,000 lbs., and the vehicle is: 

1. Typically driven over 100,000 miles per 

year, and 

2. Has less than 300,000 miles on the 

odometer at the time of installation.

2 years, unlimited miles 

ARB’s verification procedure is a multi-level verification program consisting of three 

broad levels used to establish PM reductions, which are defined by a lower bound in 

performance, and optional NOx reduction levels. Currently, reductions in NOx are not 

required for verification, but ARB’s procedure recognizes and verifies NOx reductions 

that are greater than or equal to 15 percent in 5 percent increments. 

To enable more broadly defined verifications, staff proposed amendments to the 

verification program at the Board’s January, 2008, meeting to use a verification ranking 

for NOx reductions similar to that used for PM (See Table VII-6) (ARB, 2007). Staff’s 

proposal is to use five levels, called Marks, defined by lower bounds of NOx reduction 

performance. To be eligible for verification, devices which achieve NOx reductions 

must also achieve PM reductions. Although, systems that achieve NOx reductions 

alone are currently not candidates for verification under the Procedure, staff proposed to 

change this on a limited basis. Under this amendment, staff proposed to allow for the 

verification of NOx only systems that are intended to be used on engines that are 

certified to a 0.01 grams per brake-horsepower (g/bhp-hr) PM standard. The proposed 

amendments where adopted by the Board January 24, 2008, and are expected to take 

effect by the end of 2008. To view more on the proposed changes visit the ARB 

website http://www.arb.ca.gov/regact/2008/verdev2008/verdev2008.htm. 
-85- 

Table VII-6: Diesel Emission Control Strategy Verification Levels (as adopted by 

the Board in January 2008) 

Pollutant Reduction Classification 

< 25% Not verified 

> 25% Level 1 

> 50% Level 2 PM 

> 85%, 

or < 0.01g/bhp-hr Level 3 

< 25% Not verified 

> 25% Mark 1 

> 40% Mark 2

> 55% Mark 3

> 70% Mark 4

NOx 

> 85% Mark 5

Many diesel emission control systems, in particular catalyzed DPFs, increase the 

amount of NO2 in the exhaust in order to burn off soot that has collected in the filter. 

Because NO2 has adverse health impacts arising from direct exposure as well as from 

its role in the formation of ozone and secondary particulate matter, the allowable 

increase of NO2 to total NOx emitted from a DECS to be verified was capped by the 

Board in 2006. Under these provisions, a 20 percent NO2 limit takes effect on 

January 1, 2009. Devices that meet the 20 percent NO2 limit are designated as “Plus” 

systems. Because the NO2 limit will decrease at the end of 2008, manufacturers of a 

number of currently verified devices will have to reformulate their devices and submit an 

application for re-verification, or their devices will no longer be verified. 

The verification program has broadened both the spectrum of control technologies 

available for use in California’s diesel emission control effort and the number and types 

of vehicles and engines that can be controlled. This multi-level approach to verification 

is consistent with the goal of achieving the maximum reductions in diesel PM emissions 

that are economically and technologically feasible. At this time, nearly all the verified 

emissions control strategies are exhaust aftertreatment devices. 

The verification procedure requires considerable data to demonstrate emission 

reductions and durability. Any DECS that uses a fuel additive must demonstrate that it 

is non-toxic in all media by going through a multimedia assessment. 

2. United States Environmental Protection Agency's (U.S. EPA's) Voluntary 

Diesel Retrofit Program 

The U.S. EPA has also established its own Voluntary Diesel Retrofit Program, which 

also verifies DECS using criteria which are similar to the ARB’s verification program. To 

facilitate the exchange of information between programs, ARB and U.S. EPA signed a 

Memorandum of Agreement (MOA) for the Coordination and Reciprocity in Diesel 

Retrofit Device Verification. The MOA establishes reciprocity in verifications of 

hardware or device-based retrofits, and further reinforces U.S. EPA's and ARB's 
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commitment to cooperate on the evaluation of retrofit technologies. Under the MOA, 

U.S. EPA and ARB are committed to work toward accepting PM and NOx verification 

levels assigned by the other's verification programs. Additionally, as retrofit 

manufacturers initiate and conduct in-use testing, U.S. EPA and ARB agreed to 

coordinate this testing so data generated may satisfy the requirements of each program. 

This MOA is intended to expedite the verification and introduction of innovative emission 

reduction technologies. 

3. European Union Exhaust Emission Requirements 

A diesel exhaust emission requirement in the European Unions (EU) has existed since 

the late 1980s for heavy vehicles. The current requirement regulates four groups of 

compounds, NOx, HC, CO, and PM. Heavy vehicles are measured in relations to the 

engine power (g/kWh) and are subject to two test cycles used since 2000, one transient 

and one stationary, consisting of a sequence of constant engine speed and load modes. 

In December 2003, the EU, United States, Japan, and China agreed to draw up a 

common scientific platform to measure and benchmark air pollution from vehicle traffic. 

When the EU adopted the Euro 4 requirement in 2005, DPFs were necessary on most 

larger engines. Today, the EU requirements permit somewhat higher PM and NOx 

emissions than the requirements in the U.S. and Japan (Acid News, 2004). 

C. List of ARB Verified Technologies 

Table VII-7 and Table VII-8 show a summary of DECS verified by ARB as of October 

2008. The proposed regulation would not recognize a Level 1 device as BACT. As 

such Level 1 devices are not shown in the table. 
-87- 

Table VII-7: Verified Level 3 DECS (as of October 2008) 

Product Name Technology 

Type 

P

L

U

S

PM 

Reduction 

NOx 

Reduction Applicability 

Cleaire Horizon DPF + 85% N/A Most on-road engines 

Cleaire Longview Catalyst and 

DPF 85% 25% Most 1993-2006 model year on-road engines 

Donaldson DPM DPF + 85% N/A. Most 1993-2006 model year on-road 

engines 

HUSS FS_MK DPF + 85% N/A Most on-road engines 

International 

Truck DPX DPF 85% N/A. Most 1994-2003 model year on-road Navistar engines 

Johnson Matthey 

CRT DPF 85% N/A. Most 1994 - 2006 model year onroad engines 

Johnson Matthey 

EGRT EGR/DPF + 85% 40% 

Most 1998 – 2001 model year 

International, Cummins and DDC onroad engines 

ECSystem 

Purifilter DPF + 85% N/A Most 1993-2006 model year on-road engines 

Table VII-8: Verified Level 2 DECS (as of October 2008) 

Product Name Technology Type 

P

L

U

S 

PM 

Reduction 

NOx 

Reduction Applicability 

Donaldson DPM Flow Through Filter + 50% N/A Most 1991-2002 model 

year on-road engines 

Lubrizol PuriNOx Emulsified Fuel + 50% 15% Most 1988-2003 model 

year on-road engines 

Environmental 

Solutions Worldwide 

Particulate ReactorTM 

DOC 50% N/A Most 1991-1997 model 

year on-road engines 

Whenever a verification is approved, an Executive Order (EO) is issued describing the 

engine conditions of the verification. To determine if a particular DECS will work with a 

specific engine and vehicle combination, the conditions contained in the EO must be 

followed. The EO lists the engines by engine family and other conditions of verification, 

such as minimum engine exhaust temperature. Additional evaluations may then be 

needed, such as data logging the duty cycle of the vehicles to determine its temperature 

profile, or opacity test to determine the engine out PM loading of the vehicle. 

This list is subject to change as additional systems are verified. The most current list of 

verified DECS, applicable engine families, as well as the EO letters may be found on 

the ARB web site, http://www.arb.ca.gov/diesel/verdev/vt/cvt.htm. 
-88- 

D. Summary of On-Road Installations of Exhaust Retrofits 

Retrofit technology programs have been initiated worldwide including in Sweden, 

Switzerland, United Kingdom, Hong Kong, Japan, Korea, Mexico, and other countries 

throughout the world. 

1. PM Exhaust Retrofits 

The interest in new programs for DPF has significantly grown in the last few years. A 

limited number of DPF installations began in the 1980s. However, today over 200,000 

DPFs have been installed internationally (MECA, 2006a). Presently, under the ARB 

verified technologies, several manufacturers have verified DPFs providing a PM 

reduction of around 85 percent (Level 3). DPFs have been installed in many urban 

buses and sanitation vehicles statewide and across the country. In California alone 

over 720 DPFs have been installed through the Carl Moyer program and because of 

ARB’s fleet rules. Internationally, more than 4,000 buses have been retrofitted in 

Sweden, and heavy-duty vehicles in Europe, Mexico, and Japan also have been 

retrofitted (MECA, 2006b). Additionally, DPFs have been retrofitted on heavy-duty 

vehicles in Great Britain, Germany, Finland, Denmark, Switzerland, Austria, and France. 

California has several projects utilizing DPFs on diesel vehicles currently underway. 

School buses were one of the first vehicle classes to be retrofitted. Generally, school 

bus engines manufactured before 1987 cannot be retrofitted with either a passive or 

active DPF due to the lack of availability of verified devices for 2 stroke diesel engines. 

Depending on the year manufactured, school bus engines manufactured after 1987 are 

good candidates for active and passive DPFs. 

2. Retrofits Funded through California Incentive Programs 

ARB has provided funding for many projects through the Carl Moyer Memorial Air 

Quality Standards Attainment (Carl Moyer) Program. Originally, the primary objective of 

the program focused on NOx emissions reductions, but changes were enacted by the 

Legislature in 2004 to allow consideration of projects designed to reduce exclusively PM 

or HC emissions retrofits of virtually all on-road and off-road diesel engines. A sample 

of Carl Moyer projects in the Sacramento, South Coast and Bay Area Air Quality 

Management Districts is identified in Appendix H for 2004-2005, or Year 7 of the Carl 

Moyer Program, and the devices listed reflect the newest generation of devices 

applicable to recent projects. A summary of 280 retrofits installed on engine model 

years is shown in the Table VII-9 below. 
-89- 

Table VII-9 Summary of Carl Moyer Projects 

Engine Model Year Total 

Pre 1994 17 

1994-2002 237 

2003-2006 26 

Total 280 

Since 2001, through the Lower Emission School Bus Program, ARB has successfully 

dispersed funds to equip about 3,800 diesel buses with verified DECS, of which 2,800 

are verified level 3 devices. In addition, the program partners with school districts and 

local air districts who have equipped an additional 871 verified level 3 devices. 

Additional program funding is available through Proposition 1B, the Highway Safety, 

Traffic Reduction, Air Quality, and Port Security Bond Act of 2006. Through the use of 

Proposition 1B funds, it is estimated that up to an additional 3,500 existing diesel buses 

will be retrofitted with ARB verified pollution control equipment. 

The following photos in Figure VII-5, Figure VII-6, Figure VII-7, and Figure VII-8 

demonstrate the wide variety of applications and installations possible for DPFs. 

Figure VII-5: Under Chassis Horizontal DPF Muffler Installation 
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Figure VII-6: Horizontal DPF Installation for Vertical Exhaust 

Figure VII-7: Donaldson Horizontal DPF Installation on School Bus 
-91- 

Figure VII-8: Vertical DECS Installations on Tanker and Tractor 

3. NOx Retrofits 

DPFs can be combined LNC, EGR, or SCR to achieve significant combined NOx and 

PM reductions. LNC technology is attractive because it does not require core engine 

modifications or additional infrastructure and can be installed on older engines. There 

have been more than 1,000 LNC placed systems in service in the U.S. 

Low pressure EGR retrofits have been installed in more than 1,000 engines in the U.S. 

and over 450 have been installed in engines in Hong Kong and on some existing 

Swedish urban buses (Meca, 2006a). 

SCR technology has been equipped in numerous new vehicles in Europe. The rate has 

increased from 30,000 vehicles in 2006 to 500,000 heavy-duty SCR clean diesel trucks 

in 2008 (Diesel Progress, 2008). The rate is continuing to climb as more companies 

upgrade their fleets. In addition, SCR systems have successfully been installed on 30 

line-haul trucks in Germany. In the United States, most engine manufactures have 

announced that they will add SCR aftertreatment to their heavy-duty and new midrange 

engines products beginning 2010. 

In addition, many SCR retrofit projects are currently underway in the U.S. (CCJ 

Magazine, 2008). In 2008, the Sacramento Metropolitan Air Quality Management 

District and the Sacramento Emergency Clean Air and Transportation program provided 

a $500,000 grant to retrofit a fleet of 16 older class 8 trucks owned by northern 

California grocery store chain Raley's with Johnson Matthey's latest diesel emissions 

technology, the SCRT® system. A picture of one of their installations is provided in 

Figure VII-9. Johnson Matthey is conducting a similar demonstration in southern 

California (in partnership with the South Coast Air Quality Management District) using 
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the same number of trucks, ranging from 4 to 10 years old owned and operated by 

Ralph’s Supermarkets. 

The preliminary findings on this technology after 1,000 hour testing were that the 

SCRT® system reduced engine-out NOx in the Raley's trucks by an average of 84 

percent (compared to pre-retrofit levels). The trucks involved were EGR-equipped 2004 

Cummins, 400-horsepower ISM engines (Johnson Matthey, 2008). 

A summary of on-road vehicle (and equipment) or exhaust retrofit projects completed or 

underway worldwide can be found in Appendix H. The projects are organized by 

geographical location, the sponsor of the project, and project timeframe. A description 

of each project is given (Emissions Advantage, 2005; Environment Canada, 2004; 

Ministry of Environment, 2004; U.S. EPA, 2005; DieselNet, 2002). 

Figure VII-9: Vertical SCRT® System on Tractor – 50 to 90 percent NOx reduction 

E. Anticipated Availability of Retrofits 

During the first few years of the proposed regulation, the projected increase in demand 

for verified PM DECS (typically diesel particulate filters) in California is less than 38,000 
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units per year, which is about 15 percent of the total number of diesel particulate filters 

sold nationally each year (including those sold with new engines). Staff has contacted 

several diesel particulate filter manufacturers inquiring about their manufacturing 

capacities, and they have indicated that their manufacturing facilities are capable of 

producing over a million diesel particulate filters on an annual basis. However, in the 

unlikely event that there is an unanticipated disruption in the manufacturing, distribution 

and supply for diesel particulate filters, the proposed regulation contains a provision to 

allow for manufacturing delays such that fleets are not penalized for such 

circumstances. 

F. References 

Acid News, 2004. Acid News. Emission Standards for Light and Heavy Road Vehicles. 

September 2004. 

http://www.acidrain.org/pages/publications/factsheet/factsheet17.htm

ARB, 2003. California Air Resources Board. Staff Report: Initial Statement of Reasons 

for Proposed Rulemaking, Airborne Toxic Control Measure For In-Use Diesel-Fueled 

Transport Refrigeration Units (TRU) And TRU Generator Sets, And Facilities Where 

TRUs Operate: Appendix B. October 2003. 

http://www.arb.ca.gov/regact/trude03/appb.doc

ARB, 2007. California Air Resources Board. Staff Report: Initial Statement of Reasons 

for Proposed Rulemaking, Proposed Amendments the Verification Procedure, Warranty 

and In-Use Compliance Requirements for In-Use Strategies to Control Emissions from 

Diesel Engines. December 7, 2007. 

http://www.arb.ca.gov/regact/2008/verdev2008/isor.pdf

CCJ Magazine, 2008. Commercial Carrier Journal Magazine. Cummins to use SCR in 

2010. August 2008. 

http://www.etrucker.com/apps/news/article.asp?id=71547

Diesel Forum, 2006. Diesel Forum. Retrofitting America’s Diesel Engines: A Guide To 

Cleaner Air Through Cleaner Diesel. November 2006. 

http://www.dieselforum.org/fileadmin/templates/Resources/RetrofitMaterialsFactSheets/

Retrofitting_America_s_Diesel_Engines_11-2006.pdf

DieselNet, 2002. DieselNet. Sweden: Environmental Zones Program (Trucks and 

Buses). April 2002. 

http://www.dieselnet.com/standards/se/zones.html

Diesel Progress, 2008. Diesel Progress. Power Generations Sets and Systems. 

pages 32 – 36. May 2008. 

Emissions Advantage, 2005. Final Draft: Diesel Retrofit Technology and Program 

Experience. Submitted to U.S. Environmental Protection Agency. Submitted by 

Emissions Advantage, LLC. July 29, 2005. 
-94- 

Environment Canada, 2004. Environment Canada. Low Sulphur Diesel and Transit Bus 

Retrofits Lessons Learned by the Region of Waterloo. October 10, 2004. 

http://www.ec.gc.ca/cleanair-irpur/CAOL/OGEB/ecology/LSF/LowSulphur_diesel_e.cfm

Johnson Matthey, 2008. Press Release: Johnson Matthey Technology Enables 

World's Cleanest Class 8 Diesel Trucks to Hit the Road in Sacramento. March 26, 

2008. http://ect.jmcatalysts.com/applications-trucksandbuses-news.php

MECA, 2006a. Manufacturers of Emission Controls Association. Retrofitting Emission 

Controls on Diesel-Powered Vehicles. April 2006. 

http://www.meca.org/galleries/defaultfile/MECA%20Diesel%20White%20Paper%200406%20(revised).pdf

MECA, 2006b. Manufacturers of Emission Controls Association. Clean Air Facts: 

Emission Control Retrofit of Existing Diesel Engines. February 2006. 

http://www.meca.org/galleries/default-file/dieselretrofact%200106.pdf

Ministry of Environment, 2004. Ministry of Environment of Republic of Korea. MoE 

Launches Pilot Emission Reduction Project on Diesel Vehicles. May 11, 2004. 

http://eng.me.go.kr/docs/news/press_view.html?seq=264

U.S. EPA, 2002. United States Environmental Protection Agency. Impacts of Lubrizol’s 

PuriNOx Water/Diesel Emulsion on Exhaust Emissions from Heavy-Duty Engines. 

December 2002. http://www.epa.gov/OMS/models/p02007.pdf

U.S. EPA, 2005. United States Environmental Protection Agency. Diesel Retrofit 

Project in China. November 10, 2005. 

http://www.epa.gov/OMS/retrofit/china2.htm
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VIII. CURRENT AND FUTURE ENGINE TECHNOLOGY

This chapter discusses new on-road engine standards, and current and future engine 

technologies that will be available to meet the NOx and PM performance standards of 

the proposed regulation. This includes the use of new diesel engines, as well as hybrid 

and alternatively-fueled engines. 

A. New On-Road Diesel Engine Standards 

1. Emission Standards Overview 

Heavy-duty vehicle (HDV) gaseous emissions were first regulated by California in 1969, 

and later by the U.S. EPA in 1974 (ARB, 1998a). Over the years, California had set its 

own diesel emission standards, apart from U.S. EPA, until ARB approved a State 

Implementation Plan (SIP) for ozone in 1994. The SIP contained measures calling for 

new state and national emission standards for highway heavy-duty diesel vehicles 

beginning in 2004. In June 1995, ARB, U.S. EPA, and the manufacturers of heavy-duty 

vehicle engines signed a statement of principles (SOP) agreeing on the harmonization 

of ARB and U.S. EPA heavy-duty vehicle or engine regulations. In October 1997, U.S. 

EPA adopted 2004 emission standards, along with changes to the existing federal 

averaging, banking, and trading program (ABT), for heavy-duty diesel engines sold in 

the other 49 states. ARB then adopted the U.S. EPA 2004 emission standard in 1998 

(ARB, 1998b). Table VIII-1 shows the U.S. EPA heavy duty diesel engine emission 

standard changes over the years (U.S. EPA, 2007). 
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Table VIII-1: U.S. EPA Heavy-Duty Diesel Engine Emission Standards 

Engine 

Model Year 

Hydrocarbon

(HC) 

Carbon 

Monoxide 

(CO) 

Oxides of 

Nitrogen 

(NOx) 

HC+NOx 

Particulate 

Matter 

(PM) 

1974-7813 --- 40 --- 16 --- 

1979-8314 1.5 25 --- 10 --- 

1984-87 1.3 15.5 10.7 --- --- 

1988-89 1.3 15.5 10.7 --- 0.6 

1990 1.3 15.5 6.0 --- 0.6 

1991-93 1.3 15.5 5.0 --- 0.25 

1994-97 1.3 15.5 5.0 --- 0.1 

1998-2003 1.3 15.5 4.0 --- 0.1 

2004-0615, 16 0.5 15.5 2.0 2.4/2.515, 16 0.1 

2007 + 17 0.14 15.5 0.20 --- 0.01 

To meet lower NOx emissions standards in 2004, engine manufacturers primarily used 

exhaust gas recirculation technology along with other design changes. The 2007 

engine standard required additional reductions in NOx emissions and a 90 percent 

reduction in particulate matter emissions. The U.S EPA took a “systems” approach 

when adopting the 2007 or later model year emission standards by also adopting diesel 

fuel standards with very low sulfur content. To meet the new engine standard, engine 

manufacturers further reduced NOx emissions by improving enhanced exhaust gas 

recirculation and by incorporating other design changes. However, to meet the PM 

standard, the widespread introduction of exhaust after treatment technology was 

required. Nearly all heavy-duty diesel engines manufactured in 2007 had exhaust after 

treatment control technology. 

2. Consent Decree 

In the 1990s, 7 large manufacturers of heavy-duty diesel engines (HDDEs) violated 

certification regulations by turning off, or defeating, emission control equipment during 

in-use highway driving. To address this violation, the Department of Justice, the United 

States Environmental Protection Agency and the ARB signed consent decrees with the 

7 engine manufacturers. In the consent decrees, the settling manufacturers were 

 

13 Combined HC+NOx standard of 16 g/bhp-hr. 

14 Combined HC+NOx g/bhp-hr. 

15 Under a consent decree with EPA, many engine manufacturers implemented the 2004 

standards in October 2002. 

16 Emission Standard allows for the options of 2.4 g/bhp-hr non-methane. 

17 Emission standards phased in between 2007 and 2010 for NOx and Nonmethane 

Hydrocarbons. Phase-in compliance is based on a percent-of-sales: 50 percent compliance 

between 2007 and 2009 and 100 percent compliance in 2010. No phase-in schedule applies 

to particulate matter emission standards which must be met starting with the 2007 engine 

model year. 
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required, among other things, to produce HDDEs that comply with prescribed emission 

standards that are lower than those required in they state and federal regulations at that 

time (U.S. DOJ, 1998). Specifically, these engines were required to meet a 2.5 gram 

per brake horsepower-hour (g/bhp-hr) standard for non-methane hydrocarbons (NMHC) 

plus oxides of nitrogen (NOx) emissions no later than October 1, 2002 (about 50 

percent lower than the engines produced at the time). In addition, because it was found 

that the Federal Test Procedure (FTP) was not adequate to ensure that exhaust 

emissions were controlled during all in-use driving, it was agreed that compliance with 

supplemental test procedures would be necessary. Thus, the majority of the settling 

manufacturers agreed to produce engines by October 1, 2002, that would meet 

supplemental test procedures including the Not-To-Exceed test and the EURO III 

European Stationary Cycle (ESC) test. The consent decree states that these 

requirements were to be met for a period of 2 years. Together with the FTP test, the 

supplemental test procedures required control of emissions during the majority of real 

world operating conditions to ensure that in the future defeat devices would no longer 

be employed. 

3. U.S. EPA 2007 and Later MY Emission Standards 

In January of 2001, the U.S. EPA followed the 2004 Final Rule with another rule to 

reduce emission standards for 2007 and subsequent model year heavy-duty engines, in 

light of the advance development of the aftertreatment technologies. When fully 

implemented, these emission standards represent a 90 percent reduction of NOx 

emissions, 72 percent reduction of non-methane hydrocarbon (NMHC) emissions, and 

90 percent reduction of PM emissions compared to the 2004 emission standards (ARB, 

2001). The emission standards are applicable to both natural gas-fueled engines and 

liquefied petroleum gas-fueled engines derived from the diesel cycle engine. 

The standards for NOx and NMHC emissions are phased in from 2007 to 2010, and 

provide engine manufacturers an average banking and trading program to encourage 

the early introduction of cleaner engines. The phase in schedules shown in Table 

VIII-2, which represents the percentage of new engines produced for sale in California 

that are required to meet the more stringent emission standards beginning in 2007. Full 

implementation is required starting with the 2009 model year. 

Table VIII-2: Exhaust Emission Standards and Phase-In Schedule for 2007 and 

Later Model Year Heavy-Duty Diesel On-Road Engines 

Phase in by Model Year (percent of sales) Pollutant Standard 

(g/bhp-hr) 2007 2008 2009 2010 

NOx 0.20 50% 50% 50% 100% 

NMHC 0.14 50% 50% 50% 100% 

PM 0.01 100% 100% 100% 100% 
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a) Ultra-Low Sulfur Diesel Requirement 

The U.S. EPA’s 2007 Final Rule began to phase-in in model year 2007 (full compliance 

not required until 2010) and applied to heavy-duty highway engines and vehicles (CFR, 

2007a). These standards were based on a “systems” approach. It relied on the use of 

low sulfur fuel and the use of high efficiency catalytic exhaust emission control devices 

or comparably effective technologies. ULSD (ultra low sulfur diesel) enables advanced 

pollution control technology for trucks and buses so that engine manufacturers can 

meet the 2007 emission standards. EPA has required the sulfur content to be reduced 

to 15 parts per million. Refiners began producing the cleaner burning diesel fuel, ULSD, 

for use in highway vehicles nationwide beginning June 1, 2006 (U.S. EPA, 2000). 

b) California Adoption of U.S. EPA 2007 and Later MY Emission 

Standards 

The California amendments include nearly identical emission standards, test 

procedures, and other requirements contained in the U.S. EPA’s 2007 Final Rule (ARB, 

2001b). In addition to the emission standards and test procedures, other requirements 

include the elimination of the current exemption that allows turbocharger-equipped 

engines to vent crankcase emissions to the ambient air. The amendments ensure that 

the requirements for 2007 and subsequent model year HDDEs are identical to those 

adopted by the U.S. EPA in January 2001. 

c) Credit for Early Compliance of U.S. EPA 2007 Emission Standards 

The U.S. EPA’s 2007 Final Rule provides incentives for early introduction of lower 

emitting engines (CFR, 2007b). Engines that satisfy the adopted requirements and that 

are introduced into the marketplace before 2007, will receive credits equal to 1.5 times 

the number of diesel-cycle engines that are introduced prior to 2007. For example, two 

early introduction engines will reduce the number of required phased in engines during 

2007-2009 by three. Each early engine must meet all requirements applicable to the 

2007 model year engines. If the engine complies only with the PM requirements, then 

the offsets may be used only for 2007 PM credits. Engines that can meet one half of 

the adopted NOx emission standard (0.10 grams per brake horsepower-hour) earlier 

than the phase in period, in addition to all other requirements applicable to the 2007 

model year engines, will be classified as “Blue Sky Series” engines.18 These engines 

will receive a credit of 2.0 times the number of 2007 model year compliant engines. For 

example, two “Blue Sky Series” engines will reduce the number of required phased in 

engines by 4. 

d) Averaging, Banking, and Trading program 

The U.S. EPA adopted a special provision for the Averaging, Banking, and Trading 

program in the final rule that allows a manufacturer to create a single engine family 

meeting both the phase out and phase in standards during 2007-09 through averaging 

(CFR, 2007b). These provisions allow a manufacturer to split an engine family, 

 

18 Engines with lower emission levels than the mandatory standards (U.S. EPA, 2002). 
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declaring half of the engines in it to be “phase out” engines, generating credits against 

the 2.5 g/bhp-hr NMHC+NOx standard, and half to be “phase in” engines, using these 

credits to demonstrate compliance with the 0.20 NOx standard. A single set of Family 

Emission Limits (FELs) would be declared for both subfamilies, and no banked credits 

or credits from other engine families could be used, or vice-versa. As a result, a 

manufacturer could, if desired, produce only engines meeting approximately a 1.2 g/hphr NOx FEL during the 2007-09 model years.19, 20 This corresponds to a roughly 50 

percent NOx reduction on a 2.5 g/hp-hr NOx+NMHC engine. None of these split family 

provisions affect the separate requirement to demonstrate compliance with the 0.01 

g/bhp-hr PM standard. Some manufacturers have sufficient credit so that they will not 

need to produce engines meeting the 0.2 g/bhp-hr NOx standard until 2011 or 2012. 

The NTE limits require the engines to be certified to a maximum of 0.5 g/bhp-hr. 

B. New Diesel Engines 

As discussed in above, since 2007, both ARB and U.S. EPA have required that the new 

diesel engines meet a more stringent PM and NOx emission standards. 

1. Controls to Meet PM Requirements 

For PM, all engines must meet the same PM standard of 0.01 g/bhp-hr. This has meant 

that since 2007, most medium-heavy and heavy-heavy duty diesel engines produced 

have been equipped with DPFs from the engine manufacturer. Typical DPF designs 

have included systems that are a hybrid of a purely active and passive system, which 

allows for better control of filter regeneration over a much wider set of engine operating 

parameters than either type of system could handle individually. For example, such a 

system would operate in an active mode during prolonged low temperature applications, 

while later operating similar to a passive system under high load, high temperature 

applications. 

2. Controls to Meet NOx Requirements 

While the requirements for PM controls were not phased in, for NOx, the 2007 and later 

standard of 0.2 g/bhp-hr is phased in between 2007 and 2010 (when 100 percent of 

production must meet this standard). Under the standards, only a percentage of each 

model year’s production (50 percent) is required to meet the standard, or as an 

alternative, all production from a particular manufacturer must meet an equivalent 

average. This has meant that most engines produced between 2007 and 2009 have 

actually met a 1.2 g/bhp-hr NOx standard, which is halfway between the 2006 standard 

of 2.5 g/bhp-hr and the 2010 standard of 0.2 g/bhp-hr. This has allowed engine 

 

19 The NOx FEL of the split family could vary somewhat depending on the NMHC emissions 

level, from 1.16 for an engine emitting at the 0.14 g/bhp-hr NMHC standard, to 1.22 for an 

engine emitting no NMHC. 

20 It should be noted too that this level is within the threshold values for application of the in-use 

add-on standards (1.3 g/bhp-hr NOx threshold) and the 1.5x NTE NOx and NMHC multipliers 

(1.5 g/hp-hr NOx threshold) (see 40 CFR 86.007-11(a)(3) and (4)). 
-100- 

manufacturers to phase in the introduction of new NOx control technology, which has 

been a mix of engine and combustion changes. However, to meet the 0.2 g/bhp-hr NOx 

standard, the use of exhaust aftertreatment will most likely be required. 

a) Controls to Meet the 1.2 g/bhp-hr NOx Average 

To reduce engine out NOx emissions to meet a 1.2 g/bhp-hr NOx average, engine 

manufacturers in the recent years utilized a number of different emission control 

strategies, including: 

• turbocharging; 

• cooled exhaust recirculation; 

• high pressure fuel injection; 

• changes to injection timing, and; 

• combustion chamber design optimization. 

Turbocharging is a system that utilizes engine exhaust gases, coupled with an air pump, 

to supply higher pressure intake air to engine, providing a higher air fuel ratio. 

Generally, an intercooler would be also used to reduce the compressed air temperature. 

This would permit more air to enter the combustion chamber producing better engine 

efficiency and performance. 

The use of cooled EGR will lower the peak flame temperature by diverting small 

amounts of exhaust gases to mix with the incoming air/fuel charge. Typically, the recirculated gas would be cooled by an EGR cooler before mixing with the incoming fuel. 

Changes to the combustion process, such as increased fuel injection pressures, 

changes (delays) to engine timing, and optimization of combustion chamber design will 

effectively control the temperature and pressure of the air/fuel mixture and the timing of 

the fuel injection to produce improved combustion characteristics and lower emissions. 

The use of these technologies has had the effect of decreasing cylinder intake air 

temperatures, reducing peak flame temperature, and creating more uniform combustion 

propagation in the cylinder, which reduce overall engine out NOx emissions. In using 

these technologies, it was not necessary for engine manufacturers to use higher level 

NOx control technologies, such as SCR or other exhaust aftertreatment systems. 

b) Controls to Meet the 0.2 g/bhp-hr NOx Average 

Beginning in 2010 when all engines must meet the 0.2 g/bhp-hr NOx standard, it will be 

increasingly more difficult for the engine manufactures to meet the requirements by just 

engine modification alone. Consequently, engine manufacturers have implemented or 

are considering implementing aftertreatment technology to meet these very low NOx 

standards. As will be discussed later in this chapter, this also includes the use of 

alternative fueled and hybrid engines. 
-101- 

EGR has been commonly used in 2004-2009 model year engines for NOx control, and 

one engine manufacturer had indicated that it is able to meet the 2010 NOx emission 

requirement by hardware improvement based on the EGR. Through an enhanced 

cooled EGR, coupled with the high pressure fuel injection systems, it is believed that 

sufficient NOx control can be achieved without the use of aftertreatment control in 

heavy-duty diesel engine applications. 

However, most other engine manufacturers have indicated that they intend to utilize 

SCR to achieve the required reductions in NOx emissions from 2010 and later diesel 

engines. The selection of this technology is based on a number of reasons, including: 

• the high level of NOx control it provides; 

• the maturity of the technology, and; 

• substantial improvements in fuel economy. 

Currently in Europe, there are over 300,000 commercial vehicles equipped with SCR 

systems (VDA, 2008). SCR systems can provide engine out NOx reductions of 85 

percent or greater when properly designed. In addition, heavy-duty vehicles equipped 

with SCR systems have demonstrated fuel economy savings of 5 percent or more. 

Cummins has built and shipped over 45,000 SCR engines to date and Cummins 

Emission Solutions has built and shipped over 200,000 SCR systems (Cummins, 2008). 

Currently, Cummins, Daimler (Detroit Diesel), Paccar, Volvo, and Mack have 

announced their intention to use SCR system in their 2010 model year and later product 

offerings. Staff estimates that this mean that nearly 80 percent of new engine 

production beginning in 2010 will have SCR installed (Ward’s, 2007). 

3. Impact of ABT on 2010 Engine Emissions 

As part of the 2007 on-road engine standards, U.S. EPA adopted a special provision for 

the ABT program in final rule that allows a manufacturer to create a single engine family 

meeting both the phase out and phase in standards through averaging during 2007-

2009 engine model year period. The ABT program permits the engine manufacturers to 

generate emission credits from cleaner engines to offset the emissions from new 

manufactured engines that are dirtier. 

Under this program, some manufacturers have acquired sufficient credit so they will not 

need to produce engines meeting the 0.2 g/bhp-hr NOx standard until 2011 or 2012. In 

other words, there will be engines manufactured beyond 2010 that, while certified to the 

2010 model year emission standard, will actually producing emissions higher than 2010 

emission standards because of the use of emission credits. The ABT program does 

cap the amount of credits that can be used for any given engine family, and no engine 

may be certified to a NOx level above 0.5 g/bhp-hr beginning in 2010. 

Despite the availability of credits with many engine manufacturers, as previously 

discussed, nearly all have are announced that they will use SCR in their 2010 and later 
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product offerings, greatly minimizing the potential for less NOx reductions than 

anticipated from these engines. 

C. Availability of Vehicles with Cleaner Engines 

Between 2010 and 2014, staff estimates that demand for new or near-new vehicles as a 

result of the proposed regulation will increase to about 20,000 each year. Of this, staff 

expects that about 7,000 of these vehicles each year will be purchased new, with 2010 

and later model year engines. The remaining 13,000 vehicles are expected to be nearnew used vehicles, having engines that are 5 years old or newer. 

To evaluate whether there are sufficient vehicles available to meet this demand, staff 

evaluated the availability of both new and used vehicles. In evaluating the availability of 

new vehicles, staff relied on data that shows that while new class 8 truck production 

has, as recently as a few years ago, been as high as over 250,000 per year, recent 

demand has reduced this to about 150,000 annually. Medium-heavy duty vehicle sales 

in 2006 were over 200,000 trucks (Ward’s, 2007). Since the proposed regulation will 

result in an incremental increase of only about 7,000 new vehicles a year, staff believes 

there is sufficient engine and vehicle production capacity to meet this increased 

demand. 

Staff also considered the currently available availability of near-new used vehicles. In 

its evaluation, staff found over 100,000 used trucks for sale on just two popular used 

vehicle websites (Truckpaper.com, 2008) (Commercialtrucktrader.com, 2008), with 

about 60 percent of the listings being vehicles that were 8 years old or newer. Based 

on the rate of new vehicle listings that are posted each month, staff estimates that over 

the course of year, over 150,000 used vehicle listings for near-new used vehicles would 

be made on just these two websites alone. Since staff estimates that the proposed 

regulation will necessitate the purchase of an additional 13,000 near-new used vehicles 

each year, and considering that California represents about 10 percent of the vehicle 

market, staff believes that there will be sufficient used vehicles to meet the demands of 

fleets to comply with the regulation. When one considers that this assessment did not 

include vehicles that are available for sale each day at thousands of dealerships across 

the country, this assessment is highly conservative. 

Beyond 2014, staff expects the incremental demand for replacement vehicles to 

decrease, reducing pressure on the used and new vehicle market to supply additional 

vehicles to California. 

D. Repowers 

Repowering is often an attractive strategy for owners of vehicles whose engines have 

reached the end of their useful life before the other vehicle components need 

retirement. Repowering is most cost effective when a new or newer vehicle 

replacement costs are much higher than the costs of repowering. 
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While repowering is sometimes an attractive compliance option for using newer, cleaner 

engines, it is not always a viable option for all vehicle types and configurations due to 

space limitations and other requirements associated with newer, more advanced model 

year engines. In many cases, the existing engine compartment may be too small to 

physically fit the new engine, or does not allow for proper air circulation within the 

allowable space. In addition, repowers may often require significant changes or 

modifications to the cooling system, wiring harness, engine control module, exhaust 

system, and transmission. While some vehicles repowered to 2004 to 2006 model year 

engines have been funded through the Carl Moyer Program, the feasibility of 

repowering with vehicles to 2007-2010 model year engines is unclear, and may be 

limited due to higher costs and limited space. 

E. Hybrid Vehicles 

Hybrid technology utilizes a combination of an engine and onboard energy storage 

system that provides motive power for starting and accelerating a vehicle, and 

recapturing energy when the vehicle is decelerated. Hybrid vehicles not only can 

provide reductions in diesel PM and NOx, typically through reduced fuel consumption, 

but can also reduce greenhouse gas emissions. In the future, hybrid vehicles may 

become even more effective platforms for additional improvements in fuel efficiency and 

air quality. This would arise from the use of electrification, more efficient components, 

the use of down-sized, optimized engines and combustion schemes, and through 

enhanced energy storage systems. 

1. Status of Industry and Availability 

Hybrid truck technology has made significant strides in the last several years and is now 

commercially available for certain vehicle types. However, unlike passenger cars where 

hybrid technology has been in production for nearly a decade, the first hybrid production 

trucks are only now just starting operation in the medium- and heavy-duty vehicle 

sector. Integrating hybrid technology into truck platforms presents very different 

challenges than for passenger cars, and requires different strategies and solutions 

involving packaging and weight concerns, system designs, and component sizing. 

So far, unlike the automotive industry, the leaders in medium- and heavy-duty hybrids 

are U.S. based manufacturers (WestStart-CALSTAR, 2008). Many truck and system 

manufacturers are now developing heavy hybrid prototypes or pre-production units; but 

this effort has not yet achieved critical mass. One of the key early barriers to success is 

that production volumes are low, so (incremental) prices remain high. Currently, truck 

and bus manufacturers produce a limited quantity of medium-duty hybrid vehicles for 

sale in North America. Kenworth’s class 6 T270 and class 7 T370 hybrids, 

International’s medium duty DuraStar hybrid, Freightliner Business class M2e hybrid, 

and Peterbilt’s class 7 Model 335 are just few of the hybrid vehicles available in the 

market today. The costs of hybrid vehicles are expected to decrease as production 

volumes increase. 
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2. Hybrid Application 

Diesel engines are predominant in the heavy-duty vehicle sector because of the power, 

efficiency, durability, and reliability they provide. In certain applications, a diesel-electric 

hybrid system can increase several of these important advantages, in that it can add 

more power at low engine speeds and improve diesel’s already high efficiency. Since 

hybrids create some of their efficiency gains through regenerative braking and poweron-demand, the applications that benefit most from diesel-electric hybrid technology are 

those that are driven in stop and go conditions, such as transit buses and urban delivery 

vehicles, or applications where diesel engines would otherwise idle to perform work 

while stationary, such as in utility boom trucks. Moreover, such fleets are often subject 

to public policy initiatives that require or encourage actions to reduce heavy-duty vehicle 

emissions, and diesel-electric hybrid technology is proving to be an effective means to 

meet those goals. 

Studies have shown that in an urban test cycle, a hybrid vehicle can produce fewer 

emissions (Barker and Hitchcock, 2003) and consumes less fuel (Electric Mobility 

Canada, 2007) than a comparable conventional diesel vehicle. Since hybrid vehicles 

use stored energy to assist or perform work, there is less energy demand on the 

engines. As a result, engine size can be reduced relative to a conventional vehicle 

performing a similar function. Furthermore, regenerative braking can recover otherwise 

lost kinetic energy for use later, instead of releasing it to the environment as heat. A 

utility truck is a good example of an application where stored energy is used to perform 

on-site work and the activation of the diesel engine during the on-site work is only 

needed to replenish the battery when the state of charge becomes low. In this example, 

laboratory testing has shown an average fuel savings of more than 25 percent (SwRI, 

2007). 

While long-haul, interstate tractor-trailer seldom apply their brakes (relative to more 

urban truck applications), and travel mostly on the open road, the benefit of hybrid 

technologies, which typically recoup energy “wasted” when the brakes are applied, does 

not seem to be advantageous. However, hybrid vehicle manufacturers are making 

efforts to introduce hybrid technology to this market segment by taking advantage of 

changes in terrain a vehicle would see while traveling. Using such an approach, a longhaul truck with hybrid technology could outperform a conventional tractor-trailer in terms 

of fuel savings. A good example would be a tractor-trailer transporting cargo across the 

mountains. In such case, the hybrid system on the vehicle will assist the tractor-trailer 

in climbing uphill, while recovering energy while the vehicle is descending. The first 

class 8 prototype hybrid truck using hybrid technology is expected to be placed into 

service in early 2009 (Buchholz, 2008). 

3. Future of Hybrids 

Staff believes that hybrid technology can and will play an important role in meeting 

AB32’s GHG emission reduction goal and California’s cleaner air needs. There are few 

technologies that can achieve the hybrid’s benefits of increasing efficiency while 

reducing emissions. While the production of hybrid diesel vehicles is low today, as fuel 
-105- 

costs increase and hybrid technology matures, increased use of hybrid vehicles in the 

future is anticipated. 

F. Alternative Fueled Vehicles 

The use of alternative fueled vehicles provides another viable method for fleet operators 

to reduce emissions from their fleet. Typically, alternative fuels burn cleaner than diesel 

fuel leading to reduced emission. Alternative fuels include natural gas, both liquefied 

and compressed, as well as propane, amongst the most common diesel fuel 

replacement (See Figure VIII-1). As of 2006, over 634,500 alternative fueled vehicles 

were in use in the United States, and over 105,000 of them were in California (U.S. 

DOE, 2008a). 

Natural gas, both compressed and liquid form, is the most widely used alternative fuel in 

medium- and heavy-duty vehicle applications. Natural gas is primarily produced in 

North America and costs less per equivalent gallon of diesel. While the commercial 

refueling network is relatively well developed within California, many stations remain 

open for private use only (CEC, 2008a). Several types of vehicles commonly operate on 

natural gas, including buses, street sweepers, various tractors, step vans, yard trucks, 

and solid waste collection vehicles. Currently, California has over 30,000 alternative 

fueled buses using compressed and liquid natural gas in transit fleet service. These 

types of buses typically have an incremental cost (relative to a comparable diesel 

vehicle) of around $30,000 to $40,000, but this cost can typically be recovered through 

lower per mile operating costs (UCS, 2008). 

Major vehicle manufacturers have offered natural gas buses in their product lines for 

many years. In 2007, 15 vehicle manufacturers produced heavy-duty trucks and buses 

utilizing alternative fuels (U.S. DOE, 2008b). Over the next several years, staff 

anticipates an increase in the number of alternative fueled vehicle engines available that 

are certified to the 0.2 g/bhp-hr NOx standard. For example the Cummins Westport ISL 

G engine, certified in 2008, was the first engine to meet the 0.2 g/bhp-hr NOx standard 

(Cummins Westport, 2008). In addition, certain air quality management jurisdictions 

require the use of alternative fuel vehicles in certain applications. For example, the 

SCAQMD actively requires many vehicles subject to their fleet regulations to operate on 

alternative fuels. 
-106- 

Figure VIII-1: Vehicle with Oversized Fuel Tank to Accommodate the Lower 

Energy Density of Alternative Fuels 

G. All Electric Heavy-Duty Vehicles 

With continuing improvements in battery technology, the development of heavy-duty allelectric trucks is becoming a reality. All electric vehicles can be ideal for short distance 

and inner city applications. Currently, the Port of Los Angeles, working in conjunction 

with the SCAQMD, is conducting tests on a prototype heavy-duty all electric truck. This 

electric truck is designed to pull up to 60,000 pounds with a top speed of 40 miles per 

hour. The battery on the truck can be recharged in a few hours, and the truck has a 60 

mile range. Funding has been appropriated for technology improvements, 

manufacturing and testing of an additional 20 electric trucks. Testing for the additional 

vehicles is planned to begin in mid-2008. 

H. References 

ARB, 1998a. California Air Resources Board. Staff Report: Initial Statement of Reasons 

for Proposed Amendments to Heavy-Duty Vehicle Regulation: 2004 Emission 

Standards; Averaging, Banking and Trading; Optional Reduced Emission Standards; 

Certification Test Fuel; Labeling; Maintenance Requirements and Warranties; March 6, 

1998. 

ARB, 1998b. California Air Resources Board. Final Statement of Reasons 

for Proposed Amendments to Heavy-Duty Vehicle Regulation: 2004 Emission 

Standards; Averaging, Banking and Trading; Optional Reduced Emission Standards; 

Certification Test Fuel; Labeling; Maintenance Requirements and Warranties; April 23, 

1998. 
-107- 

ARB, 2001. California Air Resources Board. Staff Report. Initial Statement of Reasons 

for Proposed Rulemaking, Public Hearing to Consider Amendments Adopting More 

Stringent Emission Standards for 2007 and Subsequent Model Year New Heavy-Duty 

Diesel Engines; September 7, 2001. 

Barker and Hitchcock, 2003. Barker, W and Hitchcock, D. Houston Advanced Research 

Center. Assessment of Potential Emission Reductions of Prototype Diesel/Electric 

Hybrid Pickup/Delivery Vehicles in the Houston-Galveston Region. November 12, 

2003. 

Buchholz, 2008. Buchholz, K. Automotive Engineering International Online. Hybrid 

Class 8 trucks coming soon from Wal-Mart. June 19, 2008. 

CEC, 2008a. California Energy Commission: Consumer Energy Center. Compressed 

Natural Gas (CNG) as a Transportation Fuel. August 2008. 

http://www.consumerenergycenter.org/transportation/afvs/cng.html

CEC, 2008b. California Energy Commission: Consumer Energy Center. Alternative 

Fueled Vehicles. August 2008. 

http://www.consumerenergycenter.org/transportation/afvs/index.html

CFR, 2007. Code of Federal Regulations. §86.004-40 Heavy-duty engine rebuilding 

practices. July 1, 2007. 

CFR, 2007a. Code of Federal Regulations. Emission Standards and Supplemental 

Requirements for 2007 and Later Model Year Diesel Heavyduty Engines and Vehicles; 

Title 40, Chapter 1, Part 86, Section 86.007-11; July 1, 2007. 

Commercialtrucktrader.com, 2008 

Cummins, 2008. Cummins 2010 Heavy Duty Customer Q & A, October 11, 2008 

Cummins Westport, 2008. Cummins Westport, Inc. Every Alternative: ISL G. August 

2008. 

http://www.cumminswestport.com/products/islg.php

Electric Mobility Canada, 2007. Electric Mobility Canada. Hybrid Vehicles in 

Commercial Fleets in the Greater Toronto Area. March 2007. 

SwRI, 2007. Southwest Research Institute. Emissions and Fuel Economy Testing of 

Three Utility Trucks. SwRI Project No. 03.11602. March 9, 2007. 

Truckpaper.com, 2008 
-108- 

UCS, 2008. Union of Concerned Scientists: Clean Vehicles. FAQ Natural Gas Vehicles. 

August 2008. 

http://www.ucsusa.org/clean_vehicles/big_rig_cleanup/natural-gas-vehicles.html

U.S. DOE, 2008a. United States Department of Energy: Energy Information 

Administration. Alternatives to Traditional Transportation Fuels 2006 (Part II - User and 

Fuel Data). Released May 2008. August 2008. 

http://www.eia.doe.gov/cneaf/alternate/page/atftables/afvtransfuel_II.html

http://www.eia.doe.gov/cneaf/alternate/page/atftables/afvtrans_v14.xls

http://www.eia.doe.gov/cneaf/alternate/page/atftables/afvtrans_v1.xls

http://www.eia.doe.gov/cneaf/alternate/page/atftables/afvtrans_v2.xls

U.S. DOE, 2008b. United States Department of Energy: Alternative Fuels & Advanced 

Vehicles Data Center. Vehicle Make and Model Search. August 2008. 

http://www.eere.energy.gov/afdc/progs/vehicles_search.php

U.S. DOJ, 1998. United States Department of Justice. DOJ, EPA Announce One Billion 

Dollar Settlement with Diesel Engine Industry for Clean Air Violations; October 22, 

1998. 

U.S. EPA, 2000. United States Environmental Protection Agency, Office of 

Transportation and Air Quality. Regulatory Announcement: Heavy-Duty Engine and 

Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements, EPA420-F00-057, U.S. EPA, December 2000. 

U.S. EPA, 2002. United States Environmental Protection Agency, Office of 

Transportation and Air Quality. Program Update: Blue Sky Series Engines, EPA420-F02-036, U.S. EPA, September 2002. 

U.S. EPA, 2007. United States Environmental Protection Agency, Office of 

Transportation and Air Quality. Selecting Buses with the Most Up-to-Date 

Environmental Controls and Safety Measures, 2007. 

http://www.epa.gov/otaq/schoolbus/selecting.htm

VDA, 2008. Verband der Automobilindustrie. Symposium at the 62nd IAA Commercial 

Vehicles. September 15, 2008. 

Ward’s, 2007. Ward’s Automotive Group. U.S. Truck Sales by GVW Class and Source, 

2007, Copyright 2008. Subscription Service. http://www.wardsauto.com

WestStart-CALSTAR, 2008, WestStart CALSTAR. Testimony for the U.S. House 

Committee on Science and Technology Energy and Environment Subcommittee June 

10, 2008. 
-109- 

IX. EXISTING DIESEL EMISSION REDUCTION REGULATIONS

A number of ARB regulations exist to reduce the emissions and risk from new and 

existing mobile diesel vehicles and equipment, and portable equipment powered by 

diesel engines. They include: 

• Public transit agency - urban buses 

• Public transit agency - transit fleet vehicles 

• Solid waste collection vehicles 

• Public agency and utility vehicles 

• Drayage trucks 

• Cargo handling equipment 

• In-use off-road vehicles 

• Transport refrigeration units 

• Portable engines and equipment 

• Diesel fuel standards 

• Off-road engine standards 

A. In-Use On-Road Diesel Vehicle Regulations 

Because diesel engines can be rebuilt to extend their useful life, as a result, diesel 

engines typically have useful lifetimes in excess of 1,000,000 miles. Current regulations 

allow the engine to be rebuilt to standards in effect at the time of manufacture rather 

than at the time of rebuild. This practice of rebuilding older engines does not provide 

the emissions reductions that replacement with a newer cleaner engine (repowering) 

does. To address this issue, the Diesel RRP recommended a large-scale program to 

retrofit diesel particulate filters, and other feasible technologies, on existing diesel 

engines. 

Since 2000, the ARB has adopted five regulations requiring the retrofit of in-use on-road 

diesel vehicles with verified DECS to reduce emissions of PM and other criteria 

pollutants. Five of those regulations apply to on-road diesel vehicles. These 

regulations have been adopted to reduce emissions from urban buses, transit fleet 

vehicles, solid waste collection vehicles, public agency and utility fleets, and drayage 

trucks. Table IX-1 lists the five regulations with their date of adoption, and the number 

of vehicles subject to each regulation. 
-110- 

Table IX-1: Regulations Requiring Retrofits of On-Road Diesel Vehicles 

Regulation Adoption Date Number of Vehicles 

Regulated 

Urban Bus February 2000 9,000 

Transit Fleet Vehicles February 2005 4,000 

Solid Waste Collection Vehicles September 2003 13,000 

Public Agencies and Utility Fleets February 2005 31,000 

Drayage Trucks December 2007 100,000 

1. Transit Urban Bus Fleets 

In February 2000, the ARB adopted the Fleet for Transit Agencies – Urban Bus 

requirements. Under the rule, urban bus operators were required to reduce NOx 

emissions from the urban bus fleet to meet a 4.8 g/bhp-hr NOx fleet average and meet 

fleet wide PM reductions relative to a baseline established in 2002. Urban bus engine 

manufacturers were required to meet a more stringent California urban bus exhaust 

emission standard through the 2006 model year, then starting with the 2007 model year, 

the standard would align with the California heavy-duty engine exhaust emission 

standards. 

Also, transit agency operators were required to choose between a diesel and an 

alternative fuel path. If a transit agency chose a diesel fuel path, then the transit agency 

was required to reduce the diesel PM emissions of its diesel urban bus fleet relative to 

its January 1, 2002, emissions by 40 percent in 2004, 60 percent in 2005, and 

85 percent in 2007. 

The alternative fuel path option has both a purchasing and emissions reduction 

component. For fleets on the alternative fuel path, at least 85 percent of annual urban 

bus purchases must be fueled by alternative fuels, which include CNG, propane (LPG), 

ethanol, methanol, gasoline/electric hybrid, electricity, fuel cells, or advanced 

technologies that do not rely on diesel fuel. For transit agencies on the alternative fuel 

path, the 85 percent exhaust PM emission reductions requirement does not have to be 

met until January 1, 2009. 

2. Transit Fleet Vehicles 

In February 2005, the ARB adopted a regulation for transit fleet vehicles. These are 

vehicles that are not urban buses, that are greater than 8,500 pounds GVWR, powered 

by a heavy-duty engine, fueled by diesel or alternative fuel, and owned and operated by 

a transit agency. Like the urban bus regulation, the transit fleet vehicle regulation has a 

NOx fleet average requirement and a requirement for PM emissions reduction. Each 

transit agency must reduce the fleet average NOx for its transit fleet vehicles to at least 

3.2 g/bhp-hr by December 31, 2007, and further reduce the average to at least 

2.4 g/bhp-hr by December 31, 2010. The regulation also requires each transit agency 

to reduce the total diesel PM emissions for its transit fleet vehicles by 40 percent as of 

December 31, 2007, and by 80 percent as of December 31, 2010, compared to baseline 
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emissions as of January 1, 2005. To allow for growth, a transit agency may also meet a 

fleet PM average of 0.01 g/bhp-hr, in lieu of achieving the final percent reduction 

requirement. Transit agencies may comply with the regulation’s requirements by using 

alternative fuels, retrofitting engines with verified DECS or by replacing with engines or 

vehicles that meet the 2007 heavy-duty engine exhaust emission standards. 

3. Solid Waste Collection Vehicles 

This regulation, adopted in September 2003, reduces diesel PM emissions from dieselfueled commercial and residential solid waste and recycling collection vehicles. It 

applies to owners of heavy-duty diesel-fueled vehicles over 14,000 pounds GVWR, with 

model year engines from 1960 to 2006, that are used to collect residential and 

commercial solid waste for a fee. Each fleet is divided into three groups based on 

engine model year: Group 1 (1988-2002), Group 2 (1960-1987), and Group 3 

(2003-2006). Vehicle owners are required to apply best available control technology 

(BACT) to their vehicles according to a specified implementation schedule that sets 

compliance deadlines and the percentage of each group that must be equipped with 

BACT by each deadline. BACT is defined in this regulation as: 

• an engine certified to the 2007 model year standard of 0.01 g/bhp-hr PM standard; 

• an engine certified to the 0.10 g/bhp-hr PM standard that is then equipped with the 

most effective ARB-verified diesel emission control strategy such as a diesel 

particulate filter; 

• application of the highest level ARB verified DECS to a diesel engine, or 

• an alternative-fuel engine, or any diesel or dual-fuel engine retrofitted with an ARB 

verified DECS that reduces PM by the greatest amount possible for the particular 

engine and application. 

4. Public Agency and Utility Fleets 

In February 2005, ARB adopted a fleet regulation to reduce diesel PM emissions from 

vehicles operated by municipalities and utilities. The regulation applies to any 

municipality or utility that owns, leases, or operates on-road diesel-fueled heavy-duty 

vehicles with a 1960 to 2006 model year medium-heavy duty or heavy-heavy duty 

engine and a manufacturer’s GVWR greater than 14,000 pounds. 

Each fleet is divided into three groups based on engine model year: Group 1 

(1960-1987), Group 2 (1988-2002), and Group 3 (2003-2006). The municipalities and 

utilities are required to apply BACT to their vehicles according to a specified 

implementation schedule that sets compliance deadlines and the percentage of each 

group that must be equipped with BACT by each deadline. BACT can be an alternative 

fuel engine, a diesel engine certified to a 0.01 g/bhp-hr PM standard, or application of 

the highest level ARB verified DECS to a diesel engine. The implementation schedule 

for most fleets covered by the regulation is summarized below in Table IX-2. 
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Table IX-2: Implementation Schedule for Most Municipal and Utility Fleets 

Vehicles 

Group Engine Model 

Years 

Percentage 

of Group to 

use BACT 

Compliance 

Deadline, as of 

December 31st 

 1 1960 –1987 

20% 

60% 

100% 

2007 

2009 

2011 

 2 1988-2002 

20% 

60% 

100% 

2007 

2009 

2011 

 3 

2003-2006 

(Includes dualfuel and bi-fuel 

engines) 

50% 

100% 

2009 

2010 

5. Drayage Trucks 

In December 2007, the ARB adopted a regulation to reduce emissions from dieselfueled drayage trucks – described as trucks that transport containers, bulk, and breakbulk goods to and from ports and intermodal rail yards. The regulation applies to 

owners and operators of diesel-fueled drayage tractors having a GVWR greater than 

33,000 pounds that operate at California ports, intermodal rail yards, or both. There are 

approximately 20,000 of these tractors frequently servicing the ports and intermodal rail 

yards. The requirements of the regulation will be implemented in two phases. In 

Phase 1, by December 31, 2009, all drayage trucks must be equipped with a 1994 to 

2003 model year engine and a level 3 verified DECS for PM emissions or they must be 

equipped with a 2004 mode year or newer engine. In Phase 2, all drayage tractors are 

required to meet the 2007 model year engine standard by December 31, 2013. All 

drayage trucks involved in work at affected ports and rail yards must be registered in a 

drayage truck registry (DTR) by late 2009. 

B. In-Use Off-Road Diesel Vehicles and Equipment 

Since 2005, the ARB has adopted two regulations requiring reductions of emissions of 

PM and other criteria pollutants from in-use off-road diesel vehicles. The types of 

vehicles subject to these regulations include cargo handling equipment at California's 

ports and intermodal rail yards and off-road heavy-duty diesel vehicles, such as those 

used in construction, mining, and industrial operations. The ARB has also adopted a 

regulation for transport refrigeration units (TRU) which are refrigeration systems 

powered by diesel internal combustion engines designed to refrigerate or heat 

perishable products that are transported in various containers, including semi-trailers, 

truck vans, shipping containers, and rail cars. Table IX-3 lists the regulations with the 

adoption date, and the number of engines subject to each regulation. 
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Table IX-3: Regulations for In-Use Off-Road Diesel Vehicles 

Regulation Adoption Date Number of Engines 

Regulated 

Cargo Handling Equipment February 2005 4,000 

In-Use Off-Road Diesel Vehicles July 2007 180,000 

Transport Refrigeration Units February 2004 40,000

1. Mobile Cargo Handling Equipment 

In December 2005, the ARB adopted a regulation to reduce emissions of diesel PM and 

NOx from mobile cargo handling equipment at ports and intermodal rail yards. Mobile 

cargo handling equipment is any motorized vehicle equipped with a diesel-cycle engine 

that is used primarily off-road to handle cargo or to perform scheduled or predictable 

maintenance or repair activities. Equipment types include, but are not limited to, yard 

trucks, top handlers, mobile cranes, sweepers, side handlers, rubber-tired gantry (RTG) 

cranes, forklifts, dozers, and loaders. 

Beginning January 1, 2007, newly purchased, leased, or rented (new) cargo handling 

equipment must meet the following performance standards: 

• new yard trucks that are registered on-road vehicles must meet the certified on-road 

engine standards for the current year; 

• new yard trucks that are not registered on-road vehicles must meet the current 

certified on-road engine standards or the final Tier 4 off-road emission standards for 

the rated horsepower of the engine; and 

• new non-yard truck equipment must ultimately meet the current certified on-road 

diesel engine standards or the Tier 4 off-road diesel engine standards. If the current 

model year off-road engine standard is pre-Tier 4, the off-road engine must be 

equipped with the highest level verified DECS within one year of acquiring the new 

equipment. 

The regulation also establishes in-use performance standards for yard trucks and nonyard truck equipment. In-use yard trucks must meet the 2007 or later current model 

year certified on-road engine standards, the certified final Tier 4 off-road engine 

standards, or apply verified DECS that will result in emissions that are less than or 

equal to the final Tier 4 off-road engine standards. Compliance begins on 

December 31, 2007, for pre-2003 model year engines and is phased in based on the 

size of the fleet. 

In-use non-yard truck equipment must comply through engine replacement and/or by 

retrofitting with the highest level available verified DECS. Replacement engines must 

meet current model year on- or off-road engine standards, and for pre-Tier 4 off-road 

engines, the highest level available verified DECS must be installed within one year. If 

retrofitting in lieu of engine replacement, a second compliance step may be required 

depending on the engine certification and the level of verified DECS installed. 
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Compliance begins on December 31, 2007, for pre-1988 model year engines and is 

phased in based on the size of the fleet. 

2. In-Use Off-Road Diesel Vehicles 

In July 2007, ARB adopted a regulation to reduce diesel PM and NOx emissions from 

in-use off-road heavy-duty diesel-fueled engines with maximum power of 25 

horsepower (hp) or greater. These engines are used to provide motive power in a 

workover rig or to provide motive power in any other motor vehicle that cannot be 

registered and driven safely on-road, and is not an implement of husbandry or 

recreational off-highway vehicle. The proposed regulation only addresses engines that 

drive self-propelled vehicles (i.e., does not apply to stationary equipment or portable 

equipment like generators). Examples include loaders, crawler tractors, skid steers, 

backhoes, forklifts, and airport ground support equipment. 

The regulation establishes increasingly stringent fleet average emission rate targets for 

PM and NOx for all off-road vehicles operating in the state. By the applicable 

compliance each year, the regulation requires each fleet to meet the fleet average 

emission rate targets for PM or apply the highest level verified DECS to 20 percent of its 

horsepower. Each year, the regulation also requires large and medium fleets to meet 

the fleet average emission rate targets for NOx or to turnover a certain percent of their 

horsepower (8 percent in early years, and 10 percent in later years). “Turnover” means 

repowering with a cleaner engine, rebuilding the engine to a more stringent emissions 

configuration, retiring a vehicle, replacing a vehicle with a new or used piece, or 

designating a dirty vehicle as a low use vehicle. If retrofits that reduce NOx emissions 

become available, they may be used in lieu of replacement as long as they achieve the 

same emission benefits. 

Large fleets are subject to the PM and NOx requirements beginning in 2010. Medium 

fleets are subject to the PM and NOx requirements beginning in 2013. Small fleets are 

subject only to the PM requirements beginning in 2015. 

Off-road diesel vehicles that are exempt from the regulation include those operated 100 

hours or less per year, vehicles used in agricultural operations, and vehicles used for 

personal use only. Vehicles that are operated for 100 hours or less have reporting 

requirements but no performance requirements. 

3. Transport Refrigeration Units 

In February 2004, the ARB adopted a regulation to reduce diesel emissions from in-use 

diesel-fueled TRUs and TRU generator set equipment used to power electrically driven 

refrigerated shipping containers and trailers that are operated in California. The 

regulation applies to owners and operators of both California–based and 

non-California-based TRUs. The engines are required to meet the in-use PM 

performance standards shown in Table IX-4 according to a schedule that is phased in 

starting December 31, 2008. The proposed in-use performance standards are aligned 

with the federal interim Tier 4 standards for new nonroad engines. 
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Table IX-4: TRU In-Use Performance Standards 

Engine 

Horsepower (hp) Emission Category Engine Certification (g/hp-hr) 

DECS 

Retrofit 

<25 hp Low Emission TRU 

(LETRU) 0.30 Level 2 

<25 hp Ultra-Low Emission TRU 

(ULETRU) 

NA 

(pick another option) Level 3 

≥25 hp Low Emission TRU 

(LETRU) 0.22 Level 2 

≥25 hp Ultra-Low Emission TRU 

(ULETRU) 0.02 Level 3 

The performance standards may be met by using a certified engine meeting the 

applicable standard, installing the required level of verified DECS, or using an 

alternative technology. The TRU emission requirements apply to in-use engines older 

than seven years. Owners/operators must meet the TRU engine performance 

standards on the following schedule. 

• MY 2001 and earlier engines must meet LETRU standards by December 31 2008, 

and ULETRU standards by December 31, 2015. 

• MY 2002 engines must meet LETRU standards by December 31, 2009, and 

ULETRU standards by December 31, 2016. 

• MY 2003 and later engines must meet ULETRU standards by December 31 of the 

seventh year past the engine’s model year (i.e., MY 2003 engines must meet 

ULETRU standards by December 31, 2010, MY 2004 by December 31, 2011, and 

so on). 

C. Portable Engines and Equipment 

Portable engines and equipment units are used for a variety of applications, such as: 

pumps, ground support equipment at airports, cranes; oil well drilling and workover rigs, 

and dredging equipment. ARB has adopted the two regulations described below that 

apply to portable engines and equipment units. One regulation establishes a uniform, 

voluntary system of statewide registration and regulation of portable equipment, while 

the other is an ATCM to minimize the public’s exposure to diesel PM emitted from 

diesel-fueled portable engines. Once registered in the voluntary program, owners and 

operators of portable engines and equipment units can operate throughout the State 

without having to obtain permits from individual air pollution control and air quality 

management districts (district). If the owner of an engine or equipment unit chooses not 

to register under the Statewide program, the engine or equipment is then subject to 

district permitting requirements. 
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1. Statewide Portable Equipment Registration Program 

Sections 41750 through 41755 of the HSC required the ARB to create and maintain a 

program for the voluntary registration and regulation of portable engines and equipment 

units in California. In March 1997, the Board adopted a regulation establishing the 

PERP which became effective on September 17, 1997. The Board has since approved 

amendments to the PERP Regulation on December 11, 1998, February 26, 2004, 

June 22, 2006, and March 22, 2007. The regulation includes recordkeeping and 

reporting requirements and sets fee schedules for registration and inspection of portable 

engines and equipment registered through the program. Most of the engines 

associated with portable equipment are diesel-fueled, making these engines also 

subject to the requirements of the Portable Engine ATCM. 

2. Portable Engine Air Toxic Control Measure 

In February 2004, the ARB adopted an ATCM that requires a phase in of cleaner 

technology engines that would result in the reduction and eventual elimination of high 

emission engines. The ATCM requires that most portable engines larger than 

50 horsepower (hp) to be certified to Tier 1, 2, or 3 U.S. EPA/ARB off-road engine 

standards by January 1, 2010. Uncertified (Tier 0) diesel engines that are designated 

as emergency use or low use may operate beyond 2010 if they will be replaced with 

Tier 4 engines within 2 years of them becoming available. In addition, starting in 2013, 

all fleets of portable engines would have to meet diesel PM emission averages that 

become progressively more stringent in 2017 and 2020. Options available to satisfy the 

fleet requirements include replacing engines, using add-on control devices, switching to 

alternative fuels, and receiving credit for electrification. 

In March of 2007, the ATCM was amended to allow statewide registration and district 

permitting of Tier 1 and Tier 2 engines that had been operating in California between 

March 1, 2004 and October 1, 2006. These amendments also allowed local air districts 

to permit resident Tier 0 engines at their discretion. In order to be newly registered in 

PERP or permitted by a district after January 1, 2010, the ATCM requires that the 

engines must be certified to the most stringent ARB or U.S. EPA nonroad emission 

standards in effect at the time of application. 

D. Diesel Fuel Standards 

Since 1993, California’s diesel fuel regulations have limited statewide the allowable 

sulfur content of California motor vehicle diesel fuel to 500 parts per million by weight 

(ppmw) and the aromatic hydrocarbon content to 10 percent by volume with a 

20 percent limit for small refiners. These regulations reduce emissions from diesel 

engines and equipment: 7 percent NOx, 25 percent PM, 80 percent sulfur oxides (SO2), 

and several toxic substances, such as benzene and polynuclear aromatic hydrocarbons 

(PAHs). These standards apply to all diesel fuel sold in California, regardless of the 

application into which it is sold. 

The regulation limiting aromatic hydrocarbon content allows refiners to sell proprietary 

formulations with aromatic hydrocarbon content greater than the basic limits, provided 
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these formulations have been certified as meeting ARB emission requirements. Most 

refiners have taken advantage of the regulation’s flexibility to produce alternative diesel 

formulations that provide the required air quality benefits at a lower cost. 

In July 2003, the ARB amended the diesel fuel regulations to reduce the maximum 

sulfur content allowed in diesel fuel from 500 ppmw to 15 ppmw. This low sulfur diesel 

regulation was needed for two primary reasons: to enable the effective use of the 

emissions control technology required by heavy-duty diesel vehicles and engines that 

must meet the U.S. EPA/ARB 2007 PM and NOx emission standards, and to enable the 

use of the exhaust treatment technologies required by new and retrofitted diesel 

engines to meet the diesel PM reduction targets established by the Diesel RRP. As of 

September 1, 2006, all diesel fuel sold at retail locations in California must meet the 

sulfur content of 15 ppmw. Beginning January 1, 2007, the requirement to use low 

sulfur diesel fuel was extended to intrastate locomotives and marine vessels. 

E. Off-Road Engine Standards 

ARB has the authority to regulate engines in new off-road equipment equal to or greater 

than 175 hp and non-preempted off-road equipment less than 175 hp. ARB and U.S. 

EPA have worked closely to harmonize the off-road compression ignition (CI) engine 

standards. ARB is preempted from regulating new farm and construction equipment 

less than 175 hp, as the U.S. EPA has the sole authority to regulate this type of 

equipment. However, ARB is not preempted from regulating in-use equipment 

regardless of engine horsepower. 

Emissions from engines utilized in off-road equipment between 175 and 750 

horsepower were uncontrolled prior to 1996. Estimates of NOx emission rates from 

uncontrolled off-road engines range from 8.2 grams per brake horsepower-hour (g/bhphr) to 14 g/bhp-hr. In January 1992, the Board adopted exhaust emission standards for 

off-road dieselcycle engines 175 hp and greater, effective beginning with 1996 model 

year engines. 

In August 1996, U.S. EPA, ARB, and off-road diesel engine manufacturers signed a 

Statement of Principles which called for harmonization of ARB and U.S. EPA off-road 

diesel engine regulations, as appropriate, in exchange for an accelerated introduction of 

progressively more stringent standards. U.S. EPA adopted emission standards in 1998 

and again in 2004 that provided for new NOx plus non-methane hydrocarbons (NMHC), 

PM and CO emissions standards for engines within different power categories in a four 

tiered approach, commonly referred to as “Tier” standards. In California, these 

standards, which are harmonized with U.S. EPA, are contained in Title 13, California 

Code of Regulations (CCR), sections 2423(b)(1). Table IX-5 summarizes the emission 

standards for these engines. 

The date upon which each tier takes effect depends on the engine horsepower (size). 

As of January 1, 2000, all engine sizes were subject to Tier 1 standards. In 2006, all 

engine sizes were subject to Tier 2, while some Tier 3 standards also took effect 

(engines less than 75 horsepower or greater than 750 horsepower do not have a Tier 3 
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standard). The Tier 4 standards are divided into two stages: interim, which begins 

between 2008 and 2012 for most engines, and final, which is effective for all off-road 

engines by 2015. The final Tier 4 standards will result in diesel engines that will be over 

90 percent cleaner than 1988 vintage engines. The Tier 4 standards require most 

engines to meet a 0.01 g/bhp-hr diesel PM emission rate and a 0.3 to 0.5 g/bhp-hr NOx 

emission rate in the 2011-2015 timeframe. 

Table IX-5: ARB and U.S. EPA Off-Road Compression-Ignition (Diesel) 

Standards (NMHC+NOx/CO/PM in g/bhp-hr where applicable) 
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F. References 

ARB, 1998b. California Air Resources Board. Final Statement of Reasons for 

Rulemaking, Including Summary of Comments and Agency Response: Public Hearing 

to Consider Amendments to Heavy-Duty Vehicle Regulations: 2004 Emission 

Standards; Averaging, Banking and Trading; Optional Reduced-Emission Standards; 

Certification Test Fuel; Labeling; Maintenance Requirements and Warranties; April 23, 

1998. 

ARB, 2001b. California Air Resources Board. Final Statement of Reasons for 

Rulemaking, Including Summary of Comments and Agency Responses: Public Hearing 

to Consider Amendments to Adopt Reduced Emission Standards for 2007 and 

Subsequent Model Year New Heavy-Duty Diesel Engines; October 25, 2001. 

CFR, 2007b. Code of Federal Regulations. NOX and Particulate Averaging, Trading, 

and Banking for Heavy-Duty Engines; Title 40, Chapter 1, Part 86, Section 86.007-15; 

July 1, 2007 

Diesel, 2005. Diesel Technology Forum: Farming, Mining & Construction; 

http://www.dieselforum.org/where-is-diesel/farming-mining-construction; 2005 
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X. PROPOSED REGULATION FOR IN-USE ON-ROAD DIESEL VEHICLES

The chapter provides an overview of the proposed regulation and explains its major 

requirements and provisions. This chapter also describes how the proposed regulation 

applies to owners of vehicles, those who hire or dispatch vehicles, rental fleets, and 

vehicle dealers. 

This chapter is intended to satisfy the requirements of Government Code 

section 11343.2, which requires that a non-controlling “plain English” summary of the 

regulation be made available to the public. 

A. Proposed Regulation Overview 

The proposed regulation would apply to any person, business, or federal government 

agency that owns or operates affected vehicles in California. Affected vehicles include 

on-road heavy-duty diesel fueled vehicles with a manufacturer’s GVWR greater than 

14,000 pounds, on-road and off-road yard trucks over 14,000 pounds GVWR, and 

diesel fueled shuttle vehicles of any GVWR that have a capacity of 10 or more 

passengers and routinely drive an average of 10 trips per day to or from airport 

terminals, marine terminals, and rail based stations. The proposed regulation would 

apply to these vehicles regardless of where the vehicle is registered – that is, it affects 

intrastate, interstate, and international vehicles. Also, any vehicle that is designed to be 

driven on-road would be subject to the regulation even though it might not be registered 

to be driven on-road. The proposed regulation would not apply to military tactical 

support vehicles, authorized emergency vehicles, and private motor homes not used for 

commercial purposes. 

The proposed regulation establishes PM and NOx emissions requirements for the 

vehicles subject to the regulation. These requirements will be discussed in greater 

detail later in this chapter. The regulation is included in Appendix A, and an outline of 

the subsections of the regulation is provided in Appendix A1. 

In general, the regulation would require owners to reduce PM and NOx emissions from 

their fleet by upgrading the vehicles to meet BACT standards for PM and NOx. The 

BACT standard for PM is an engine equipped with the highest level verified DECS for 

PM or an engine originally equipped with a diesel particulate filter (DPF) by the engine 

manufacturer. The BACT standard for NOx is an engine newly manufactured in 2010 or 

later, or a 2010 emissions equivalent engine. A fleet may meet these performance 

requirements by retrofitting a vehicle with a verified DECS that will achieve PM or NOx 

reductions or both as required, replacing an engine with a newer cleaner one, or 

replacing a vehicle with one having a cleaner engine. 

The regulation provides three options for complying with the performance requirements. 

A fleet would be able to comply with a prescribed BACT schedule that would determine, 

based on the vehicle’s engine model year, which engines would be required to have the 

highest level verified DECS and which would be required to be replaced. A fleet could 

also meet a BACT percent limit option. This option specifies the minimum number 
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engines each year that must have applied the highest level verified DECS to meet the 

PM performance requirements regardless of engine model year, and the minimum 

number of engines required to meet the 2010 engine requirements to satisfy the NOx 

performance requirements. Engines originally equipped with a DPF by the 

manufacturer would count towards the number of verified DECS. The third option is the 

fleet average option. The owner would use PM and NOx emission factors established 

by the regulation to calculate the average emissions of the fleet. By the applicable 

compliance date each year, the owner would have to demonstrate that the fleet met the 

PM and NOx fleet average emission rate targets set by the regulation. The targets 

would decline over time, requiring fleets to reduce their emissions further as time goes 

on. 

During the first two years of the regulation, starting January 1, 2011, fleets would be 

required to install PM verified DECS for certain engine model years. The regulation 

would then require owners to reduce both PM and NOx emissions from the fleet by 

accelerating engine or vehicle replacement between January 1, 2013 and the end of 

2022 so that by January 1, 2023, all engines would be the cleanest available – that is, 

manufactured in 2010 or later or be retrofitted to achieve equivalent emission 

reductions. 

The proposed regulation would also establish requirements for any in-state or out-ofstate motor carrier, Californiabased broker, or any California resident who hires or 

dispatches vehicles subject to the regulation. In addition, California sellers of a vehicle 

subject to the proposed regulation would have to notify vehicle buyers that the 

regulation may apply. 

B. Purpose 

As stated in subsection (a) of the proposed regulation, the purpose of the regulation is 

to reduce emissions of diesel PM, NOx, other criteria pollutants, and greenhouse gases 

from in-use on-road diesel-fueled vehicles. While the regulation contains performance 

requirements for PM and NOx emissions reductions, it does not require the reduction of 

greenhouse gas emissions. Reductions of greenhouse gas emissions will be achieved 

through credits to promote the use of hybrid diesel vehicles and alternative fuels, and 

through the replacement of older vehicles with newer, more efficient vehicles. 

C. Applicability 

The proposed new regulation would apply to any person, business, or federal 

government agency that owns or operates affected vehicles in California. Affected 

vehicles include heavy-duty diesel fueled vehicles with a GVWR greater than 14,000 

pounds, on-road and off-road yard trucks over 14,000 pounds GVWR, and diesel fueled 

shuttle vehicles of any GVWR that have a capacity of 10 or more passengers and 

routinely drive an average of 10 trips per day to or from airport terminals, marine 

terminals, and rail based stations. The proposed regulation would be applicable 

regardless of where the vehicle is registered. 
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The proposed regulation would not apply to military tactical support vehicles, authorized 

emergency vehicles, and private motor homes not used for commercial purposes. The 

regulation would also not apply to vehicles subject to the following regulations: 

• Solid waste collection vehicle as defined by title 13, CCR, section 2021(b); 

• Municipality and utility owned vehicles as defined by title 13, CCR, section 2022(a), 

except that vehicles owned or operated by a privately owned utility would become 

subject to the regulation on January 1, 2021; 

• Urban buses as defined by title 13, CCR, 2023(a)(13); 

• Transit fleet vehicles as defined by title 13, CCR, 2023(a)(12); 

• Mobile cargo handling equipment at ports and intermodal rail yards; 

• Off-road vehicles subject to title 13, CCR, sections 2401, 2421, 2411, 2432, and 

2449; 

• Dedicated snow-removal vehicles, as defined in section 2025(d)(12) 

• Two-engine cranes, as defined in title 13, CCR, section 2449(c)(56); and 

• Historic vehicles as defined in section 2025(d)(28). 

1. How Regulation Applies to Sellers and Dealers of Vehicles 

The proposed regulation applies differently to sellers of affected vehicles, such as 

vehicle dealers and auction houses or financing companies who do not operate the 

vehicles, than to other fleet operators. The only part of the regulation that would apply 

to such sellers of vehicles is the disclosure of regulation applicability requirement in 

section 2025(v). That is, sellers must notify buyers that the regulation may apply. 

Vehicles that are temporarily owned by dealerships or are incidentally owned by 

financing companies and are awaiting sale would not be subject to the recordkeeping, 

reporting, or performance requirements of the regulation provided the vehicles are not 

being operated (other than operation for sales demonstration or maintenance). Thus, 

dealers and financing companies that do not operate vehicles and that do not offer them 

for rent would not need to report their vehicles and need not comply with any 

performance requirements of the regulation. Dealers that hold vehicles for sale and also 

rent them out or lease them would be responsible for compliance as described below for 

rental and lease companies. 

2. How Regulation Applies to Rental and Lease Companies 

The regulation would treat rental and lease companies just like any other fleets. Thus, 

the default situation in the regulation is that rental vehicles are the responsibility of the 

rental company rather than the user. 

For vehicles leased for a period of a year or more, if a rental or lease company and the 

lessee agree in the lease agreement that the vehicle will be the responsibility of the 

lessee, it may be excluded from the rental company’s fleet that year and included in the 

fleet of the lessee. If rental and leasing companies are selling vehicles which were 
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formerly part of their rental fleet and the rental vehicle was operated less than 1,000 

miles and 100 hours in the past year, such vehicles may be treated like other vehicles 

being held for sale, as described in the section above. 

Vehicles under a long term lease of period of a year or more that was in place before 

the regulation takes effect would be the responsibility of the lessee rather than the 

leasing company. 

D. Definitions 

The proposed regulation provides definitions of all terms that are not self-explanatory. 

There are approximately 70 definitions to help clarify the regulation’s requirements. The 

definitions listed in subsection (d) of the proposed regulation were either developed by 

staff, with input from the public during workshops and workgroup meetings, or the 

California Code of Regulations, California Vehicle Code (VC) or existing ARB 

regulations or other sources. Please refer to Appendix A, subsection (d) for a list of 

definitions. 

1. Combat and Tactical Support Equipment 

Combat and tactical support equipment means equipment that meets military 

specifications, is owned by the U.S. Department of Defense and/or the U.S. military 

services or its allies, and is used in combat, combat support, combat service support, 

tactical or relief operations or training for such operations. Such equipment would be 

exempt from the proposed diesel regulation for national security reasons. Appendix F 

contains a letter from the Department of the Navy listing the equipment types included 

as combat and tactical support equipment. 

2. Fleet 

A fleet is defined as all of the vehicles under common ownership by a person, business, 

or governmental agency. A fleet may consist of one or more vehicles. This definition in 

the proposed regulation also includes additional clarification for federal fleets, rental and 

lease fleets, fleets owned by school bus operators and school districts, and small fleets. 

a) School Bus and School Bus Sub-Fleets 

A school bus fleet is a fleet of school buses designed, used or maintained for the 

transportation of an pupil to or from school or school activities, which meets the 

definition outlined in the VC, section 545. School bus sub-fleets means the school 

buses in a fleet comprised of school buses and vehicles other than school buses. 

b) Small Fleets 

This definition also includes a definition of a small fleet, which is a fleet of 3 or fewer 

vehicles under common ownership. Common ownership or control means a vehicle 

being owned or managed by the same person or entity or controlled by a single board of 

directors. This would include vehicles being operated by different legal subsidiaries 

under a corporate umbrella. Therefore, a fleet under common ownership or control 
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could not be split into smaller regional fleets around the state to utilize the small fleet 

provisions. 

3. Agricultural Operations 

Agricultural operations are defined in the proposed regulation as the activity of growing 

or harvesting crops for the primary purpose of making a profit or providing a livelihood 

including any horticultural, viticultural, aquacultural, forestry, dairy, livestock, poultry, 

bee or farm product. However, raising plants at nurseries that sell exclusively retail are 

not included in the definition. 

The definition also includes the cutting or removing of both of timber, other solid wood 

products, including Christmas trees, and biomass from forestlands for commercial 

purposes. The services also include all the related work associated such as 

construction and maintenance of roads, fuel breaks, firebreaks, stream crossings, 

landings, skid trails, beds for falling trees, fire hazard abatement, and site preparation 

that involves disturbance of soil or burning of vegetation following forest removal 

activities. Forest operations include the cutting or removal of trees, tops, limbs and or 

brush which is processed into lumber and other wood products, and or for landscaping 

materials, or biomass for electrical power generation. Forest operations do not include 

conversion of forestlands to other land uses such as residential or commercial 

developments. 

4. Agricultural Vehicle 

Agricultural vehicles are those that are used exclusively for agricultural operations. 

These vehicles include dedicated fertilizer and crop protection chemical delivery trucks, 

farmer owned vehicles used to support the farm, vehicles that come to the farm to 

perform specialized farm work, and vehicles that transport harvested crops to first 

processing centers. Vehicles that perform other functions in addition to agricultural 

operations do not fit the definition of an agriculture vehicle. 

Vehicles that are used exclusively for delivering fertilizer or crop protection chemicals to 

farms can be considered agricultural vehicles if the company holds the proper license 

and the vehicles display the required placards. These chemical or fertilizer supply 

trucks are limited to those that are required by the United States DOT to have certain 

placards, and whose owners are licensed to sell pesticides or fertilizers by the California 

Department of Pesticide Regulation or the California Department of Food and 

Agriculture, respectively. Trucks exclusively involved in agricultural operations, 

including flatbed trucks, logging trucks, silage trucks, or water trucks that are owned by 

a farming business, are also considered agricultural vehicles. Additionally, vehicles that 

are not owned by a agricultural business but exclusively perform a agricultural function 

on a farm, such as spreading manure, also fall under the definition of an agricultural 

vehicle. Finally, vehicles used exclusively to transport harvested agricultural products 

from the field or ranch to first point of processing such as packinghouse or a creamery 

are deemed agricultural vehicles. Such vehicles would include tomato trucks, milk 

trucks, grain trucks, trucks hauling grapes and others. 
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E. Performance Requirements 

The proposed regulation provides three options for complying with the NOx and PM 

performance requirements. These three options are described below. Once a fleet 

meets any one of these compliance options for NOx and PM, they have met the 

performance requirements for that year. In addition, the proposed regulation allows 

fleets to meet the NOx and PM performance requirements separately, using different 

compliance options for each pollutant. For example, a fleet may choose to meet the 

fleet average option for NOx, and separately comply with the BACT percent limit for PM. 

1. BACT Schedule 

The proposed regulation provides that a fleet would be able to comply with the 

proposed NOx and PM performance requirements by complying with a prescribed 

BACT schedule that would determine, based on the vehicle’s engine model year, which 

engines would be required to have the highest level verified DECS and which would be 

required to be replaced. The proposed BACT schedule is provided below in Table X-1. 

A fleet may meet these requirements by retrofitting a vehicle with a verified DECS, 

replacing an engine with a newer cleaner one, or replacing a vehicle with one having a 

cleaner engine. 

Table X-1: Best Available Control Technology Compliance Schedule 

Compliance 

Deadline, 

as of January 1 

Engine Model-Years BACT Requirements 

2011 Pre-1994 PM BACT 

2012 2003 – 2004 PM BACT 

2005 – 2006 PM BACT 2013 1994 – 1999 NOx and PM BACT 

2000 – 2002 NOx and PM BACT 2014 All Model Years PM BACT 

2015 Pre-1994 NOx and PM BACT 

2016 2003 - 2004 NOx and PM BACT 

2017 2005 - 2006 NOx and PM BACT 

2018 All pre-2007 No new requirements 

2019 All pre-2007 No new requirements 

2020 All pre-2007 No new requirements 

2021 2007 or equivalent NOx and PM BACT 

2022 2008 NOx and PM BACT 

2023 2009 NOx and PM BACT 

The BACT requirement for PM is an engine equipped with the highest level verified 

DECS for PM or an engine originally equipped with a DPF by the engine manufacturer. 

To install the highest level verified DECS, a fleet owner must install all available Level 3 

verified DECS on their engines first. If no Level 3 DECS is verified for the vehicle’s 
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engine, then the fleet owner must install Level 2 verified DECS to meet the PM BACT 

requirement. No regulatory credits provided for Level 1 DECS. The BACT requirement 

for NOx is an engine newly manufactured in 2010 or later or a 2010 “emissions 

equivalent engine”. A discussion of emission equivalent engines is provided below. 

For fleets using this compliance option, starting January 1, 2011, any vehicle with a 

model year engine older than 1994 would have to meet the PM BACT requirements. 

This requirement would expand to include 2003 and 2004 model year engines in 2012. 

Then, beginning January 1, 2013, the regulation would require owners to reduce both 

PM and NOx emissions from the fleet by accelerating engine or vehicle replacement 

through the end of 2022, such that by 2023, all engines would be the cleanest available 

– that is, manufactured in 2010 or later or be retrofitted to achieve equivalent emission 

reductions. 

2. BACT Percentage Limits 

A fleet may also choose to comply with the proposed NOx and PM performance 

requirements by meeting a BACT percent limit option. This option specifies the 

minimum number of engines each year that, as a percentage of all the vehicles in a 

fleet, must have the highest level verified DECS installed to meet the proposed PM 

BACT requirements, regardless of engine model year. Engines in the fleet that were 

originally equipped with a DPF by the manufacturer would count towards the number of 

verified DECS installed. 

In addition, this option also specifies the minimum number of engines that, also as a 

percentage of all the vehicles in a fleet, are required to meet the proposed BACT 

requirement for NOx. Like in the BACT Schedule option described above, the proposed 

BACT requirement for NOx is an engine newly manufactured in 2010 or later, or a 2010 

emissions equivalent engine (See Table X-2). 
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Table X-2: Percent of Fleet That Must Comply with PM and NOx BACT 

Standard 

Percent of Total Fleet Complying with 

BACT Compliance Deadline

as of January 1 PM BACT NOx BACT 

2011 25% N/A 

2012 50% N/A 

2013 75% 25% 

2014 100% 50% 

2015 100% 50% 

2016 100% 60% 

2017 100% 80% 

2018 100% 80% 

2019 100% 80% 

2020 100% 90% 

2021 100% 90% 

2022 100% 90% 

2023 100% 100% 

The use of this option allows a fleet to select the order of vehicles that will be retrofit and 

replaced, regardless of their age. This will provide additional flexibility to fleets such 

that they may be able to keep older vehicles in their fleet longer than would be allowed 

under the BACT schedule. 

3. Fleet Averaging Option 

The third option to meet the proposed NOx and PM performance requirements is 

through the use of a fleet average. Under this option, the fleet owner would use PM and 

NOx emission factors established by the regulation to calculate the average emissions 

of the fleet. The appropriate NOx and PM emission factors are shown below in Table 

X-3 and Table X-4, respectively. 
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Table X-3: PM Emissions Factors by Engine Model Year (g/mile) 

Engine Certification 

Standard Model Year 

Medium-Heavy Duty 

(MHD) 

Heavy-Heavy Duty 

(HHD) 

Pre-1991 1.65 3.36 

1991-1993 0.84 1.25 

1994-2006 0.43 0.81 

2007-2009 0.06 0.11 

2010 and newer 0.06 0.11 

Table X-4: NOx Emissions Factors by Engine Model Year (g/mile) 

Engine Certification 

Standard Model Year 

Medium-Heavy-Duty 

(MHD) 

Heavy-Heavy Duty 

(HHD) 

2003 and older 14.2 22.0 

2004-2006 6.7 12.0 

2007-2009 4.0 7.0 

2010 and newer 0.8 1.6 

Using these emission factors for each vehicle, a fleet owner would have to demonstrate 

that the fleet met the proposed PM and NOx fleet average emission rate targets set by 

the regulation by the applicable compliance date each year. The targets decline over 

time, requiring fleets to reduce their emissions further as time goes on. The fleet 

average targets for PM and NOx are shown in Table X-5 below. 
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Table X-5: Fleet Targets for PM and NOx (g/mile) 

PM Targets for each 

compliance deadline 

NOx Targets for each 

compliance deadline 

Compliance 

Deadline, 

as of January 1 MHD HHD HHD HHD 

2011 0.38 0.710 - - 

2012 0.29 0.530 - - 

2013 0.17 0.320 8.5 14.4 

2014 0.06 0.110 5.8 9.8 

2015 0.06 0.110 5.8 9.8 

2016 0.06 0.110 4.6 7.8 

2017 0.06 0.110 4.0 6.0 

2018 0.06 0.110 4.0 6.0 

2019 0.06 0.110 4.0 6.0 

2020 0.06 0.110 3.2 4.4 

2021 0.06 0.110 3.2 4.4 

2022 0.06 0.110 1.6 3.0 

2023 0.06 0.110 0.8 1.6 

Similar to the BACT percent limit option discussed above, the use of this option allows a 

fleet to select the order of vehicles that will be retrofit and replaced, considering their 

relative emissions. This will provide additional flexibility to fleets such that they may be 

able to keep older vehicles in their fleet longer than would be allowed under the BACT 

schedule, so long as they have cleaner vehicles (with lower emissions) to offset the 

older vehicles that have higher emissions. 

4. Emission Equivalency for Older Engines 

In meeting the performance requirements of the proposed regulation, staff intends to 

allow for the use of verified DECS to achieve reductions for both PM and NOx 

emissions. To provide clarity to fleets as to how these DECS would compare to certified 

engines, staff’s proposal includes specific standards to establish emission equivalency. 

Staff has proposed emission equivalency standards to 2004, 2007, and 2010 certified 

engines. These equivalency standards are provided in Table X-6 below. 
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Table X-6: PM and NOx Equivalency Standards 

Performance Standard Using DECS Engine Emission 

Performance 

Standard 

(Model Year) 

Actual Engine 

Model Year NOx PM 

2010 and newer Met by definition DPF equipped by 

engine manufacturer 

2007-2009 70% reduction 

Met if equipped with 

DPF by engine 

manufacturer 

2010 and newer 

2004-2006 85% reduction Highest Level DECS1

2007-2006 Met by definition DPF equipped by 

engine manufacturer 

2004-2006 40% reduction Highest Level DECS 2007-2009 1

2003 and prior 70% reduction Highest Level DECS1

2004-2006 Met by definition N/A2

2004-2006 2003 and prior 55% reduction N/A2

1

 As defined by title 13, CCR, section 2025(d)(34).

2 These engines do not meet PM BACT since they were not equipped with a 

DPF from the engine manufacturer. 

As can be seen in Table X-6, to meet a 2010 emission equivalency standard, a 2007 

model year vehicle would need a verified DECS that achieved a 70 percent reduction of 

NOx provided the vehicle was equipped with a DPF by the manufacturer. If no DPF is 

in place then the highest level verified DECS is required. Similarly, to meet a 2007 

emission equivalency standard, a 2004 engine would need a verified DECS that 

achieved a 40 percent reduction of NOx and the highest level verified DECS. To meet a 

2004 emission equivalency standard, a 2003 engine would need to have a verified 

DECS that achieved a 55 percent reduction of NOx. No PM reduction would be 

needed, since these engines were not produced or certified using a DPF. 

F. Other Requirements 

1. School Bus Fleets 

Diesel-fueled school buses as defined in the VC, section 545 with a GVWR above 

14,000 pounds will need to install a verified DECS to meet the requirements of the 

proposed regulation. Unlike all the other vehicle sectors subject to the NOx and PM 

performance requirements of the proposed regulation, school buses would only be 

required to meet the proposed PM requirements, and would be subject to several 

special provisions and timetables specifically designed for this sector. School buses 

manufactured prior to April 1, 1977, before minimum federal safety standards were 

established, will be required to be removed from service by January 1, 2012. All 

remaining diesel-fueled school buses must meet one of the following three proposed 

compliance options: 
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• BACT Compliance Schedule (See Table X-7) 

• BACT Percentage Limits Compliance Option 

• Fleet Average Compliance Option 

School buses would be considered in compliance with the proposed regulation when 

they have installed the highest level verified DECS by the designated compliance date 

under the option selected. Depending on the compliance option chosen and the verified 

DECS that is installed, a school bus fleet may be subject to proposed reporting 

requirements. 

If it is not technologically feasible for the school bus engine to be retrofitted with a 

Level 2 or Level 3 verified DECS by the compliance deadline, then compliance may be 

delayed annually until January 1, 2018 provided no verified DECS becomes available. 

By January 1, 2018, these school buses that cannot be retrofitted would need to have 

their engines replaced with an engine that is equipped with a highest level DECS or the 

school bus would need to be replaced with one meeting the PM BACT criteria. 

Table X-7: Proposed PM BACT Schedule for School Buses 

Compliance Deadline as of January 1 Engine Model Year 

2011 2000 and newer 

2012 1994 – 1999 

2013 1987 – 1993 

2014 Pre – 1997 

Engines equipped with a DPF by the engine manufacturer as original equipment are 

considered in compliance with the requirement. School buses registered as historic 

vehicles or designated as low use vehicles are exempted from performance 

requirements; however, there are reporting requirements for these vehicles. Low use 

school buses are vehicles operated less than 1,000 miles per year. 

As discussed later, Proposition 1B, approved by California voters in 2006, will provide 

$200 million, through the Lower Emission School Bus Program, to replace all remaining 

eligible pre-1977 model year school buses. Additionally, these bond funds will replace 

approximately 1,000 model year 1977 to 1986 school buses, and install DPFs on about 

3,500 buses. All buses replaced or retrofitted through the Lower Emission School Bus 

Program will be in compliance with the proposed regulation. 

2. Drayage Trucks 

Drayage trucks are diesel-fueled, heavy-duty trucks that transport containers, bulk, and 

break-bulk goods to and from ports and intermodal rail yards to other locations. 

Drayage trucks are already subject to requirements of title 13, CCR, section 2027, 

(known as the drayage truck rule) which requires all vehicles entering ports and 

intermodal rail yards to have PM controls by December 31, 2009, except for 2004 to 

2006 model year engines. 
-133- 

The proposed regulation will add a phase one requirement for drayage trucks with 2004 

to 2006 model year engines. The proposed regulation requires that 2004 model year 

engines be equipped with the highest level verified DECS by January 1, 2012, and that 

2005 to 2006 model year engines be equipped with the highest verified DECS by 

January 1, 2013. This requirement would align the drayage truck rule with the proposed 

regulation. In addition, the proposed regulation would require that all drayage trucks 

comply with the PM and NOx performance requirements starting January 1, 2021. 

3. Privately-Owned Utilities 

In addition to other changes that are applicable to municipalities, as described in 

Chapter XI, the proposed regulation would require that all utility vehicles comply with the 

PM and NOx performance requirements starting January 1, 2021. 

4. Verified DECS Installation and Maintenance 

Fleet owners choosing to comply using verified DECS, they would have to meet 

installation requirements for verified DECS. Before installing a verified DECS on a 

vehicle, the fleet owner should be familiar with the Executive Order for the verified 

DECS and would need to: 

• Ensure that the verified DECS is verified for use with the engine and vehicle, as 

described in the Executive Order for the verified DECS; 

• Ensure that use of the vehicle is consistent with the conditions of the Executive 

Order for the verified DECS; 

• Ensure that the diesel emission control strategy is installed in a verified 

configuration; and 

• Ensure that the engine to be retrofit is tuned up so that it meets engine 

manufacturer’s specifications prior to verified DECS installation. 

This requirement also specifies that the owner of a vehicle with a verified DECS would 

have to ensure that the maintenance on the verified DECS and engine is performed as 

specified by each manufacturer. 

5. Labeling 

The proposed regulation would include requirements for the application of labels on 

certain agricultural vehicles and two-engine sweepers. Agricultural vehicles that 

operate below specific mileage thresholds (limited-use and low-use agricultural 

vehicles) would need to be labeled within 30 days of required reporting date. Similarly, 

two-engine sweepers that have Tier 0 auxiliary engines would be limited to operating 

less than 250 hours per year until January 1, 2014 would also need to be labeled within 

30 days of their required reporting date. No other labeling requirements are proposed. 
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6. Requirements for Entities Hiring and Dispatching Vehicles 

The proposed regulation would require in-state and out-of-state motor carriers, 

California-based brokers and California residents that operate or direct the operation of 

any vehicle to retain records documenting that all of the drivers they hire or dispatch are 

in compliance with the proposed regulation. These motor carriers or brokers would 

have an affirmative defense for violations by an operator they dispatched if they can 

demonstrate that they verified the compliance status of the operator at the time they 

were hired or dispatched. 

7. Adding Vehicles 

For fleets not meeting the “BACT Schedule” requirements, fleet owners must report to 

the ARB within 30 days the addition of any vehicle to the fleet; and the fleet may not 

operate that vehicle in California prior to reporting. The fleet owner must also 

demonstrate that the fleet complies with the requirements of the proposed regulation. A 

fleet owner who selects the BACT percentage limits option may not add vehicles that 

cause the percentage calculated for the fleet to fall below the percentage for the 

previous compliance date. Furthermore, a fleet owner who selects the fleet averaging 

option may also not add vehicles that cause the fleet to exceed the fleet average target 

rates for the previous compliance date. 

G. Special Provisions and Compliance Extensions 

The following special provisions and compliance extensions are proposed. Fleets 

utilizing these special provisions and compliance extensions must meet, as appropriate, 

all the record keeping and reporting requirements, as described later in this chapter. 

1. Small Fleets 

Fleets with three or fewer vehicles would be exempt from the proposed 2010 and 2011 

PM exhaust retrofit requirements. By January 1, 2013, a small fleet would need to show 

that it has at least one vehicle equipped with a 2004 model year or newer engine having 

a verified highest level DECS installed. By January 1, 2018, that vehicle would need to 

meet the proposed PM and NOx performance requirements of the regulation. If these 

requirements are met with a vehicle that has a 2010 or equivalent engine, no more 

action is required. If these requirements are met with a vehicle that has a 2007 to 2009 

engine or equivalent, the engine will need to meet 2010 performance standard between 

2021 to 2023. For fleets with two vehicles, the second vehicle would be required to 

meet the PM and NOx performance requirements by January 1, 2014. 

For fleets of three vehicles, two compliance paths are available. After having shown 

that it equipped its first vehicle with a 2004 model year or newer engine with a highest 

level verified DECS, a fleet of three vehicles could comply by: 

• having its two remaining vehicles meet the PM and NOx performance requirements 

by January 1, 2014, or; 
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• electing to have the second vehicle meet the 2010 engine emissions requirements 

by January 1, 2014, and the third vehicle meet the PM and NOx performance 

requirements by January 1, 2016. 

2. Agricultural Vehicle Provisions 

The proposed agricultural vehicle provisions provide additional time for certain 

agricultural vehicles to be upgraded to meet 2010 engine emission performance 

requirements, and allows them to operate without PM exhaust retrofits up to specified 

dates. By January 1, 2023, all agricultural vehicles must meet the 2010 model year 

engine emissions requirements. 

Agricultural vehicles that operate below the mileage thresholds would be exempt from 

the PM and NOx performance requirements for a specified period provided they remain 

below the thresholds shown in Table X-8. These are defined as either Low-Mileage 

Agricultural or Limited-Mileage Agricultural vehicles, based on their annual mileage as 

shown in Table X-8. Vehicles that operate over these thresholds would have to meet 

the same requirements as any other vehicle subject to the proposed regulation. 

Table X-8: Agricultural Vehicle Mileage Threshold 

Type of Exempt 

Vehicle 

Model Year 

Engine 

Mileage Threshold 

(Less Than) 

Expiration Date of 

January 1 

Low-Mileage Ag Any 10,000 2023 

1995 and older 15,000 

Limited-Mileage Ag 1996 to 2005 20,000 

2006 and newer 25,000 

2017 

To qualify, an agricultural fleet operator must report, by January 31, 2010, the number 

of low-mileage and limited-mileage agricultural vehicles that operated in 2009. Once 

reported, the number of each type of these may not increase in any fleet. Until 

January 1, 2017, an agricultural fleet operator may operate no more than this number of 

vehicles below each of their respective mileage thresholds. Then, beginning in 2017, 

the agricultural fleet operator is limited to operating only that number of vehicles 

reported in 2010 as being low-mileage agricultural vehicles. Vehicles that had been 

designated as limited-mileage agricultural vehicles must meet the NOx and PM 

performance standards of the proposed regulation, or replace a retiring low-mileage 

agricultural vehicles that will be retired. For the purposes of this provision, retire means 

that the vehicle is scrapped, rendered inoperable, or sold out of the agricultural fleet. 

Also, vehicles qualifying as specialty agricultural vehicles would be exempt from the PM 

and NOx performance requirements until January 1, 2023. Specialty agricultural 

vehicles include a specific subset of agricultural vehicles, including: 

• nurse rigs; 

• cotton module trucks; 

• feed trucks used by cattle and calf feed lots, and; 
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• water trucks owned and operated by farmers for dust control and irrigation. 

However, under these provisions, the number of specialty agricultural vehicles operating 

in the San Joaquin Valley Air Basin cannot exceed 1,100 trucks, and the total number 

operating statewide cannot exceed 2,200, as reported to the ARB. Once these 

thresholds are reached, a vehicle that would otherwise meet the definition of specialty 

vehicle would not be eligible for consideration as a specialty agricultural vehicle, and 

would have to meet the other provisions of the proposed regulation. 

3. Exemption from the Performance Requirements 

a) Low Use Vehicles 

A vehicle that is operated less than 1,000 miles and 100 hours per year would be 

exempt from all performance requirements. Staff has also proposed to allow an out-ofstate vehicle the option, available only to be used once each year per fleet, to operate a 

single vehicle in California for a 3 day period regardless of miles travelled . 

b) Delay from the NOx Performance Requirements 

Staff proposes to delay the proposed NOx performance requirements for vehicles 

operated more than the low use thresholds (1,000 miles), but below a specified higher 

mileage threshold. However, these vehicles would still remain subject to the proposed 

PM requirements. For truck-tractors and vehicles with a GVWR greater than 33,000 

pounds, the higher mileage threshold would be 7,500 miles per year. In addition, yard 

trucks, as well as vehicles that use power take off to perform work while stationary must 

also demonstrate that they operate less than 250 hours per year. All other vehicles 

would be eligible to delay the proposed NOx performance requirements if operated less 

than 5,000 miles per year. These same vehicles that use power take off to perform 

work while stationary must also operate less than 175 hours per year. This delay in 

meeting the proposed NOx performance requirements would expire on January 1, 2021. 

Vehicles that operate exclusively in less polluted areas of the State would not be 

required to meet the engine replacement requirements until January 1, 2021, but would 

remain subject to the PM requirements. These vehicles would remain subject to the 

reporting requirements, and would require to comply with the electronic tracking system 

requirements described later in section (I). These areas are shown below in Figure X-1. 
-137- 

Figure X-1: NOx Exempt Areas of California 

Also, vehicles that are defined as unique vehicles would not be subject to the 

replacement requirements until January 1, 2021, but would still be included in 

determining the fleet average or the BACT percent limit. However, these unique 

vehicles would remain subject to the proposed PM performance requirements. For a 

vehicle to be eligible for the delay of the NOx performance requirements, the owner 

would need to demonstrate the following: 

• A used vehicle having a 2007 model year or newer engine and, that performs a 

similar function is not available. 

• A suitable cab and chassis upon which the vehicle bed could be mounted is not 

available 

• A verified NOx emissions control device that could reduce the vehicle’s exhaust NOx 

emissions is not available. 

• The vehicle’s engine has been equipped with the highest level verified DECS, if one 

is available and can be safely installed. 
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Staff is also proposing that truck-tractors exclusively pulling 57 foot trailers be eligible to 

delay the NOx performance requirements until January 1, 2018, provided the engine is 

a 2004 model year engine and the highest level verified DECS is installed. All other 

vehicles in a fleet having such tractors would need to meet the proposed NOx and PM 

performance standards on the prescribed schedule. 

4. Requirements for Valid Operator Number 

Fleets that opt to comply with the proposed performance standards of the regulation by 

using the BACT percent limit or the fleet average options, as well as fleets that utilize 

the small fleet provisions, or any other special provisions of section 2025(l), (o)(1), (2), 

(8) or (9) must possess one of the following: 

• a valid California motor carrier of property number, 

• a valid identification number assigned by the United States DOT, or 

• a valid operating authority number issued by the Public Utilities Commission, or 

other applicable valid operating authority number approved by the Executive Officer. 

5. Credit for Hybrid and Alternative Fuel Vehicles 

A fleet would receive credit towards compliance with the proposed fleet average 

requirements for using hybrid vehicles as long as it can be demonstrated that the fuel 

economy of the hybrid vehicle is at least 20 percent better than an equivalent vehicle. 

The credit would expire January 1, 2018. The credit would “double count” the number 

of hybrid vehicles in the fleet that are used to calculate the PM and NOx fleet emissions 

average and the target rates, or for determining compliance with the percent limit 

requirements. 

Also, for fleets using vehicles equipped with alternative fuel or heavy-duty pilot ignition 

engines, credit would be granted for the purpose of calculating the NOx and PM fleet 

average target rates towards compliance with the fleet average. In using this credit, the 

PM emission factor would be zero, and the NOx factor would be based on the emission 

factor corresponding to the engine standard for which the engine is certified. 

6. Special Provisions for Certain Two-Engine Sweepers 

Staff is proposing that the auxiliary engine of a private two-engine sweeper be treated 

the same as the propulsion engine of any other vehicle subject to the proposed 

regulation. In doing so, staff is proposing that the auxiliary engine in these vehicles be 

required to meet the PM performance requirements on the same schedule as the 

propulsion engine. 

However, to provide more time for certain sweepers that are used infrequently, staff is 

proposing that private two-engine sweepers that have Tier 0 auxiliary engine not be 

allowed to operate more than 250 hours per year until January 1, 2014, and thereafter 

be allowed to keep the sweeper and operate it up to 100 hours per year. 
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Additional discussion about provisions applicable to private two-engine sweepers is 

provided in Chapter XI and XVI. 

7. Credit for Early Action 

Vehicles that are retrofit with the highest level DECS before January 1, 2010, would be 

exempt from meeting the NOx BACT replacement requirements until January 1, 2014. 

This provision incentivizes vehicle owners to install verified DECS before the required 

deadlines. 

8. Verified DECS Failure 

If a verified DECS fails or is damaged during the warranty period and it cannot be 

repaired, then it must be replaced with the same level or higher verified DECS. Should 

a DECS fail or be damaged outside of its warranty period and it cannot be repaired, 

then replacement depends on if the fleet still meets applicable targets without the failed 

device. If the fleet does not meet the most recent compliance target without the 

damaged device, then the DECS must be replaced with the highest level verified DECS 

within 90 days. 

 

9. Fuel-Based Strategy for Verified DECS and Use of Experimental 

Strategies 

The proposed regulation contains special provisions that would allow a fleet to use a 

Level 2 fuel based strategy across its whole fleet if the highest level verified DECS for a 

large portion of its fleet would be a Level 2. The rule also contains a special provision 

that would give up to a two year extension for fleets that used a fuel-based strategy but 

find that it had been discontinued. 

Also in the proposed regulation, an owner could apply to the Executive Officer to use an 

experimental, or non-verified, DECS. This compliance method can be used if a verified 

DECS is not available or if the owner can demonstrate that an existing verified DECS is 

not feasible for their vehicle or application, or if use of the non-verified strategy is 

needed to generate data to support verification of the strategy 

10. Vehicles Used for Emergency Operation 

The proposed regulation defines vehicles used for emergency operations, and proposes 

to exempt them from the proposed NOx and PM performance requirement, but they still 

must be reported. For vehicles used both for emergency operations and for other 

purposes, hours of operation and mileage accrued when the vehicle is used for 

emergency operations would not need to be included when determining whether the 

vehicle meets the low use vehicle definition of section (d)(38). Records documenting 

dispatch by a governmental emergency management agency for travel to and from an 

emergency event must be kept. 
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11. Compliance Extension for Manufacturer Delays 

A vehicle owner would not be penalized for equipment manufacturer delays for verified 

DECS or vehicles, as long as the owner placed the order for the required equipment or 

vehicle at least four months prior to the required compliance date or within 60 days of a 

verified DECS failure. The new equipment or vehicles would, however, need to be 

immediately placed into operation upon receipt. 

12. Verified DECS That Impair Safe Vehicle Operation 

The proposed regulation provides for instances where a owner may request the 

Executive Officer to determine if a verified DECS should not be considered the highest 

level available because it cannot be safely installed or operated on a particular vehicle 

or its use would violate occupational safety and health requirements or local air district 

permit conditions. The requesting party would have to provide documentation to support 

its claims that the verified DECS cannot be safely installed or operated. Documentation 

would have to include reports and findings of federal, state or local government 

agencies, independent testing laboratories, engine or equipment manufacturer studies, 

or other equally reliable source. The Executive Officer would review the documentation 

submitted and make his or her determination based upon the totality of the evidence. 

The Executive Officer would send a written determination letter to the requesting party 

within 60 days of the request being submitted. The section also provides details on 

hearing and appeal procedures. 

H. Reporting 

For the proposed fleet average and BACT percent limit compliance options in the 

proposed regulation, accurate and effective enforcement of the proposed regulation will 

depend on ARB getting an accurate depiction of the entire fleet from each fleet owner. 

That is, an inspector will not be able to gauge compliance by looking at any one vehicle. 

Thus, accurate reporting will be essential. To this end, the reporting requirements in 

subsection (q) of the regulation are thorough. 

Owners who choose a compliance option other than the BACT schedule would be 

required to notify the ARB of this selection. These owners would be required to submit 

annual compliance reports that demonstrate compliance with the requirements of the 

proposed regulation. The first annual compliance report would be due 

January 31, 2011 (for the period of January 1, 2010 through December 31, 2010), and 

annually thereafter. Compliance reports must include the following information: 

• Fleet owners name; 

• Name of company or agency; 

• Motor carrier identification number; 

• Corporate parent name (if applicable); 

• Company parent taxpayer identification number (if applicable) 

• Company taxpayer identification number; 
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• Street address and mailing address; 

• Name of responsible person; 

• Title of responsible person; 

• Contact name; 

• Contact telephone number; 

• Contact email address (if available) 

Fleets owners would also need to report a list of each vehicle subject to this regulation, 

along with the following information for each vehicle: 

• Vehicle type; 

• Vehicle identification number; 

• Vehicle manufacturer; 

• Vehicle model; 

• Loaded vehicle weight rating as defined in section 2025(d)(31); 

• Vehicle model year; 

• License plate number; 

• Where the vehicle is registered and type of registration plate; 

• Whether the vehicle will be designated as a low-use vehicle; 

• Whether the vehicle is used for emergency operations; 

• Whether the vehicle is a specialty vehicle as defined in section 2025(m)(2); 

• Whether the vehicle is a hybrid vehicle as defined in section 2025(d)(29); 

• Whether the vehicle is an alternative-fueled vehicle as defined in section 2025(d)(6). 

For each engine, the manufacturer, model, family, serial number, and model year must 

also be reported. For reporting the verified DECS installed, fleet owners must report the 

type, manufacturer, family name, serial number, date installed, and verification level and 

year of verification. 

To ease reporting, staff intends to develop and provide electronic reporting forms via the 

internet for both the initial and annual reporting requirements. Fleets would also be able 

to report via hard-copy if preferred. In addition, staff plans to conduct outreach to fleet 

owners to explain and clarify these reporting requirements. 

I. Electronic Tracking System 

Fleet owners may be required to use an electronic tracking device, such as a global 

positioning system (GPS), to comply with some of the requirements of the proposed 

regulation. The tracking device must acquire date, time, and engine-on data at a 

minimum of 15 minute intervals, with no more than 30 minute data gaps. The tracking 

device must also acquire location data for vehicles claiming to operate exclusively in 

NOx exempt areas and for out-of-state vehicles that must document low-use in 
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California when their total miles of operation exceeds 1,000 miles and total hours of 

operation exceed 100 hours. Tracking records must also be collected by an 

independent entity with no business relationship to the owners of the vehicles being 

tracked, other than to provide the tracking service. 

J. Recordkeeping, Retention and Audits 

Fleet owners would be required to maintain all applicable records for all vehicles subject 

to the proposed regulation. For vehicles meeting the proposed BACT schedule, the 

fleet owner would maintain verified DECS records where these are used to comply with 

the BACT schedule, or records of any verified DECS failure and replacement, or 

records to document a manufacturer delay. In addition to these records, fleet owners 

complying with the BACT percent limits or the fleet averaging option would have to 

maintain copies of the all information previously discussed. 

The proposed regulation requires owners to maintain records to document changes 

they have made since the last reporting. For example, if a vehicle is added to a fleet, 

the owner has 30 days to demonstrate that the fleet is still in compliance with the 

requirements for the previous compliance date. If an inspector views a fleet in the 

interim period before the fleet has submitted the documentation, and finds a vehicle that 

was not included in the last reporting, the owner would have to demonstrate, using bills 

of sale, purchase orders, shipping records, or other documentation, when the vehicle 

entered the fleet. 

The fleet owner or responsible person shall maintain the records for each vehicle 

subject to the reporting and record keeping requirements of the proposed regulation and 

until 3 years after the vehicle is retired or January 1, 2025, whichever is earlier. If the 

ownership of the fleet is transferred, the seller is required to transfer the fleet records to 

the buyer. Dealers must also maintain records of the disclosure of regulation 

applicability for three years after the sale. 

ARB staff can request an audit to verify the accuracy of a fleet owner’s records. The 

proposed regulation describes the responsibility of the fleet owner to make the 

requested records available to ARB. If the records are not made available within 30 

days of the request, the ARB may assess penalties for non-compliance. This includes 

reimbursing the ARB auditor per diem and travel expenses under certain conditions as 

determined by the Executive Officer. 

K. Right of Entry 

The proposed regulation would provide ARB inspectors the right, for the purpose of 

inspection to determine compliance with the regulation, to enter any facility where 

vehicles are located or vehicle records are kept. Inspectors would need to first obtain 

any necessary safety clearances and present proper credentials. 
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L. Disclosure of Regulation Applicability 

The proposed regulation would require vehicle sellers disclosure to vehicle purchasers 

that they are potentially affected by the regulation. Any person residing in California 

selling a vehicle with an engine subject to this regulation must provide the following 

disclosure in writing to the buyer on the bill of sale: 

“An on-road heavy-duty diesel or alternative-diesel vehicle operated in California 

may be subject to the California Air Resources Board Regulation to Reduce 

Particulate Matter and Criteria Pollutant Emissions from In-Use Heavy-Duty 

Diesel Vehicles. It therefore could be subject to exhaust retrofit or accelerated 

replacement requirements to reduce emissions of air pollutants. For more 

information, please visit the California Air Resources Board website at 

http://www.arb.ca.gov/dieseltruck”. 

M. Penalties 

Any person who fails to comply with the regulation or who submits false information will 

be treated under sections 39674, 39675, 42400, 42400.1, 42400.2, 42402.2, and 43016 

of the Health and Safety Code. The Executive Officer, in assessing penalties, will 

consider factors, including but not limited to the willfulness of the violation, the length of 

time and magnitude of noncompliance, and whether the fleet made an attempt to 

comply. 
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XI. PROPOSED CHANGES TO OTHER DIESEL EMISSIONS CONTROL REGULATIONS

This chapter discusses modifications proposed for a number of existing ARB diesel 

regulations. These changes are intended to ensure that these existing regulations and 

the proposed regulation do not create overlapping requirements for the same vehicles, 

as well as to clarify a number of issues with the existing regulations, to provide 

additional compliance flexibility, and to generally improve enforceability of the existing 

regulations. 

The other existing regulations proposed to be amended are: 

• Diesel Particulate Control Measure for Public Agency or Utility On-road Heavy- duty 

Diesel-fueled Vehicles 

• In-Use On-Road Diesel-Fueled Heavy-Duty Drayage Trucks 

• Regulation for In-Use Off-Road Diesel Vehicle Regulation 

• Regulation to Establish a Statewide Portable Equipment Registration Program 

• Regulation for Mobile Cargo Handling Equipment at Ports and Intermodal Rail Yards 

• Airborne Toxic Control Measure to Limit Diesel-Fueled Commercial Motor Vehicle 

Idling 

• Exhaust Emissions Standards and Test Procedures – 1985 and Subsequent Model 

Year Heavy-Duty Engines and Vehicles 

• Airborne Toxic Control Measure for Diesel Particulate Matter from Portable Engines 

Rated at 50 Horsepower and Greater 

A. Proposed Modifications for Cranes and Sweepers 

Cranes with two engines and private sweepers with two engines are subject to multiple 

regulations, with varying compliance dates and different levels of stringency. To better 

regulate these vehicles, and ensure that the clean-up of these vehicles is conducted 

efficiently, staff is proposing a number of changes to other regulations currently 

regulating cranes and sweepers with two engines. This will ensure that achieving 

emissions reductions from both engines on these vehicles does not create unnecessary 

overlapping requirements or add unnecessary costs. Details on the basis for the 

proposed changes are discussed in Chapter XVI. 

1. Cranes 

Two-engine cranes are mobile diesel-powered machines with a hoisting mechanism 

mounted on a specially constructed truck chassis or carrier; one engine is used for 

propulsion, and a secondary engine is used to lift and move materials and objects. 

There are three general categories of two-engine cranes: lattice boom (conventional), 

all terrain, and truck mounted. All terrain and truck mounted cranes are very similar and 

can be both categorized as truck mounted hydraulic cranes. The motive or drive engine 

is typically an on-road engine. The secondary engine is an off-road engine. 
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Without the proposed modifications, two-engine cranes would continue to be required to 

meet varying requirements in the following regulations: 

• Portable Engine and Equipment Regulation 

• Statewide Portable Equipment Registration Program 

• Mobile Cargo Handling Equipment at Ports and Rail Yards Regulation 

• In-Use Off-Road Diesel Vehicle Regulation 

To establish a better regulatory structure that would reduce emissions from these 

vehicles more effectively and at a lower cost, staff is proposing the following changes to 

existing regulations: 

• Add both engines of two-engine cranes to the off-road vehicle regulation (the drive 

engine would be included regardless if it is certified as an on-road engine or as an 

off-road engine) 

• Remove the upper engine of a two-engine crane from the scope of the Portable 

Engine Equipment Regulation and exclude the same engine from most performance 

requirements in the PERP. However, the proposal would not remove the registration 

and inspection requirements of PERP. 

• Remove all cranes (excluding rubber tire gantry cranes) from the scope of the Cargo 

Handling Equipment regulation, thereby placing the control of two-engine and offroad cranes used at ports and intermodal rail yards in the In-Use Off-Road Diesel 

Vehicle Regulation, and single engine cranes in the proposed regulation. No 

changes would be made regarding rubber-tired gantry cranes. 

Excluding single-engine cranes from the Cargo Handling Equipment regulation would 

further support consistency in complying with one regulation, since many owners only 

provide crane service to the ports on a temporary basis but have fleets that would be 

required to comply with other overlapping regulations. 

2. Proposed Modifications for Sweepers 

Private two-engine sweepers have many of the same regulatory issues as two-engine 

cranes. To address this, staff is proposing to control the emissions from the drive 

engines and auxiliary engines on private two-engine sweepers (that is, they are not 

subject to the Fleet Rule for Public Agency and Utilities) somewhat differently, in that 

both engines in two-engine sweepers are proposed to be included in the proposed 

regulation. This change would ensure the requirements of cleaning-up both engines 

would not conflict. 

Under staff’s proposal, the drive (propulsion) engine of a private two-engine sweeper 

would be treated the same as the propulsion engine of any other vehicle subject to the 

proposed regulation. In doing so, staff is proposing that the auxiliary engine in these 

vehicles be required to meet the proposed PM performance requirements on the same 

schedule as the propulsion engine, and that private two-engine sweepers that have an 
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uncertified Tier 0 auxiliary engine not be allowed to operate more than 250 hours per 

year through January 1, 2014, and up to 100 hours per year thereafter. 

Without the proposed changes, privately owned two-engine sweepers are impacted by 

the following regulations: 

• Portable Engine and Equipment Regulation 

• Statewide Portable Equipment Registration Program (PERP) 

• Mobile Cargo Handling Equipment at Ports and Rail Yards Regulation 

• Public Agency and Utility Fleets Regulation 

To establish a better regulatory structure that would reduce emissions from these 

vehicles more effectively and at a lower cost, staff is proposing the following changes to 

existing regulations: 

• Remove the upper engine of a privately owned two-engine sweeper from the 

scope of the Portable Engine and Equipment Regulation and exclude the same 

engine from most performance requirements in PERP. However, the proposal 

would not remove the registration and inspection requirements of PERP. 

• Amend the Public Agency and Utility Fleet regulation to allow municipalities to 

receive retirement credit for the sale of used two-engine sweepers having 2004-

2006 model year propulsion engine to businesses in California. 

• Remove all sweepers from the scope of the Cargo Handling Equipment 

regulation, making them subject to the proposed regulation. 

Removing these vehicles from the Cargo Handling Equipment regulation would provide 

consistency for owners and operators in complying with only one regulation and would 

address other issues such as safety, certification, and compliance flexibility. 

B. Proposed Amendments to Existing Regulations 

1. Purpose and Definitions of Diesel Particulate Matter Control Measures 

Definition 

This regulation (title 13, CCR, section 2020) defines terms that apply generally to 

several regulations that control diesel PM emissions. The proposed amendments would 

modify the definition of the term “municipality”. The current definition includes agencies 

of the United States of America, thereby making federal agencies subject to the 

regulation for Public Agency and Utility Fleets. The proposed amendment would modify 

the definition of municipality to exclude Federal agencies and consequently exclude 

fleets owned by the Federal government from the Public Agency and Utility Fleet 

Regulation. Tribal (Indian) reservations and rancherias are also proposed to be 

excluded in the revised definition of “municipality”. Fleets owned and operated by these 

entities would be subject to the proposed regulation. 
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2. Public Agency and Utility Fleets 

Staff is proposing modifications that would expand the scope of this regulation and 

would add new language to address ambiguities and omissions in the regulation when 

initially adopted. 

a) Scope and Applicability 

Staff’s proposed revision of section 2022(a) would expand the scope and applicability of 

the regulation to include light heavy-duty engines that were inadvertently omitted from 

the original scope of the regulation. Staff is also proposing to expand the scope to 

include 2007 model year and newer engines certified under the ABT provisions at PM 

levels greater than the 2007 model year standard of 0.01 g/bhp-hr. This revision is 

consistent with the original intent of the regulation to require upgrades of all engines that 

did not meet the PM BACT standard of 0.01 g/bhp-hr. This revision would ensure that 

any 2007 MY engines certified under the ABT provisions to a higher PM emissions 

levels would be subject to the BACT requirement. 

b) Compliance Extensions 

In conjunction with the expanded scope and applicability, a new provision section 

(2022.1(d)(7)) would allow municipalities and utilities to apply for a one-year extension 

of the intermediate 2009 compliance deadline for light heavy-duty engines. The 

municipality or utility would have to document that the addition of the light heavy-duty 

engines to the fleet would prevent the fleet from complying with the 2009 compliance 

deadline. 

Staff does not expect many municipalities and utilities to apply for this extension since a 

telephone survey of 38 municipalities and public utilities indicated that most fleets had 

already accounted for all of their heavy-duty vehicles over 14,000 pounds GVWR, 

including those with light heavy-duty engines, in their total fleet for the regulation. 

c) Retirement Credit for Out-Of-State Sales 

A municipality or utility may receive credit toward their BACT requirement by retiring a 

vehicle according to the provisions of the rule. Retirement credit is granted if any of the 

following apply: 

• the engine is dismantled for scrap; 

• the vehicle is sold outside of California; 

• the vehicle is transferred to another person or entity in California after it has been 

brought into compliance with the BACT requirements, or; 

• the vehicle has been converted for use as a low usage or low-population low usage 

vehicle. 

Staff’s proposed amendments provide a means of ensuring that owners receive BACT 

credit for vehicles sold out-of-state, and that vehicles sold out-of-state for retirement 

credit cannot be re-sold in California unless they met the BACT requirements. 
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New language proposed in section 2022.1(f)(1)(k) would establish a process for 

qualifying a vehicle for retirement through out-of-state sales. This process requires the 

municipality or utility to obtain a “VIN Stop” – a Department of Motor Vehicles (DMV) 

registration hold based on a vehicle identification number that prevents a vehicle from 

being re-registered in California after it is retired. A municipality or utility would not be 

granted BACT credit for a retired vehicle re-registered in California if the municipality or 

utility sold the vehicle prior to the VIN Stop being issued. This proposal formalizes an 

informal process that was initiated earlier by staff in cooperation with the DMV. 

Proposed language in section 2022.1(h) establishes contract requirements for out-ofstate sales through a third party vehicle seller. The contract language would ensure 

that the seller informs buyers of the prohibitions against re-registering or operating 

retired vehicles in the state. 

Staff is also proposing to modify the definition of “retirement” in section 2022(b)(8) to 

grant credit for the sale within California of two-engine sweepers with 2004 – 2006 

model year propulsion engines, provided that, in the case of private sector buyers, they 

comply with the proposed regulation. This would make cleaner used sweepers 

available for purchase by private fleets. 

d) Optional Delay of Immediate and Final Compliance Date for Group 2 

and Group 3 Privately Owned Utility Vehicles 

For privately-owned utilities, staff is proposing an optional two-year delay of the 

intermediate and final BACT PM requirement deadlines, accompanied with a 

requirement that by December 31, 2013, 30 percent of their total fleet vehicles meet a 

2010 engine emission performance standard, and that an additional 20 percent of their 

total fleet vehicles meet a 2007 or newer engine emission standard. 

e) Other Changes 

Staff is proposing to add new definitions for “lease”, “operate”, “sold outside of the State 

of California”, “third party vehicle seller”, “dual engine street sweeper”, and “VIN stop” to 

support the changes being proposed. 

 

3. Mobile Cargo Handling Equipment at Ports and Intermodal Rail Yards 

As discussed above, staff is proposing to exclude sweepers and mobile cranes from the 

scope of the Cargo Handling Equipment regulation. No changes would be made 

regarding rubber-tired gantry cranes. 

4. Drayage Trucks 

Staff is proposing modifications to the drayage truck regulation to add a phase one 

requirement for drayage trucks with 2004 – 2006 model year engines, a change in 

liquefied natural gas (LNG) fueled truck applicability, and clarifications on the 

applicability of alternative and dual-fueled diesel trucks. 
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Staff is proposing to require that 2004 model year engines be equipped with the highest 

level verified DECS for PM by January 1, 2012, and that 2005-2006 model year engines 

be equipped with the highest level verified DECS for PM by January 1, 2013. 

Staff is also proposing additional changes to be consistent with the proposed regulation. 

Staff is proposing to define pilot injection LNG fueled trucks consistent with the 

alternative fueled vehicle definition in the proposed regulation. This change would 

exempt pilot injected LNG fueled trucks from the emissions requirements of the drayage 

truck regulation. Staff is also proposing to include ‘alternative diesel-fueled and dualfueled’ trucks in the applicability section (b)(1). 

Finally, staff is proposing to add or modify the following definitions: ‘Dual-Fueled 

Engine’, ‘Alternative Diesel Fuel’, ‘Compression Ignition Engine’, and ‘Diesel-Fueled’. 

All definition additions or changes would not modify the applicability or intent of the 

drayage truck regulation. 

5. In-Use Off-Road Diesel Vehicle Regulation 

Staff is proposing to change the scope of the regulation for in-use off-road diesel 

vehicles to include both the drive engine and the secondary engine of all two-engine 

cranes operated in California. The drive engine would be included regardless of 

whether it is certified as an on-road engine or as an off-road engine. Because of this, 

staff is proposing to add a definition of “two-engine crane,” in title 13, CCR, section 

2449(c)(56) 

Staff is also proposing to modify section 2449.3(b)(2)(c) to exclude the horsepower 

from cranes from a fleet’s maximum horsepower. 

In addition, just as other on-road vehicles are required to have on-road engines when 

sold new and if operated on the road, on-road vehicles subject to the In-Use Off-Road 

Diesel Vehicle Regulation (such as workover rigs and on-road two-engine cranes) must 

have on-road engines in them when sold new. New language is proposed in section 

2449(e)(15) that would clarify the repower requirements for workover rigs and other onroad vehicles subject to the regulation. The proposed amendments would require that 

any replacement engine must be an on-road engine if the workover rig or other on-road 

vehicle is to be registered and driven on public roadways. 

Staff is proposing to modify section 2449 (e)(7) to clarify the exemption provision for 

low-use vehicles. The current regulatory language in the section exempts low-use 

vehicles from all of the performance requirements in section 2449(d). The proposed 

modifications would require low-use vehicles to comply with the requirements for adding 

vehicles to the fleet and with the idling requirement. This is consistent with staff’s 

original intent in proposing the regulation. 
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6. Portable Engine and Equipment 

Staff is proposing amendments to the Portable Engine and Equipment Regulation as it 

applies to two-engine cranes and two-engine sweepers. Under the Portable Equipment 

Regulation, currently these engines must be replaced by December 31, 2010, if they do 

not meet U.S. EPA or ARB emission certification standards. In many cases these 

vehicles have Tier 0 engines and it is not feasible, if not impossible, to repower these 

vehicles with new certified engines. Meaning, the only alternative would be to replace 

the entire vehicle with a new vehicle having a certified engine. To address this, staff is 

proposing to amend the Portable Equipment Regulation to exclude the secondary 

engines on two-engine cranes and privately owned two-engine sweepers from the 

requirements of the Regulation. The Regulation would also be amended to delete the 

diesel PM standards and fleet requirements of title 17, CCR, section 93116.3(b)(4) for 

lattice boom cranes. Lattice boom cranes would be included in the proposed definition 

of two-engine cranes that would be added to the In-Use Off-Road Diesel Vehicle 

Regulation. 

Additionally, staff is proposing that two new sections be added to the Portable 

Equipment Regulation. New section 93116.1(b)(8), would require the auxiliary engine 

on a two-engine crane to comply with the requirements of the regulation for in-use offroad diesel vehicles, and new section 93116.1(b)(9) would require the secondary 

engine on a privately owned two-engine sweeper to comply with the requirements of the 

proposed regulation. 

Staff is also proposing to amend the Portable Equipment Regulation by adding a new 

definition for “crane” which would cross-reference the proposed new definition of twoengine crane in the In-Use Off-Road Diesel Vehicle Regulation. A new definition for 

“street sweeper”, which references the new proposed definition of “dual-engine street 

sweeper” in the regulation for Public Agency and Utility Fleets will also be added. 

7. Statewide Portable Equipment Registration Program (PERP) 

The PERP requirements are proposed to be amended in order to establish new 

performance requirements for registered secondary diesel engines on two-engine 

cranes and privately owned two-engine sweepers. With this change, these secondary 

engines would be exempt from the performance requirements of the PERP regulation, 

except for the limits on opacity of emissions. 

For two-engine cranes, the secondary engine would be required to comply with the 

applicable requirements of the In-Use Off-Road Diesel Vehicles Regulation. In addition, 

the PERP regulation would define “crane” by referencing Section 2449 (c) of the In-Use 

Off-Road Diesel Vehicle Regulation and its definition of a “two-engine crane”. 

For privately owned two-engine sweepers, the PERP regulation would define “street 

sweeper” such that it would cross-reference the definition of “dual engine street 

sweeper” in the Public Agency and Utility Fleets Regulation. The secondary engine of a 
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two-engine sweeper would have to comply with the applicable performance 

requirements of the proposed regulation. 

In addition, currently non-registered Tier 0 secondary engines on cranes and sweepers 

would be allowed to be newly registered under PERP, and would then be subject to the 

inspection requirements and fees listed in the PERP regulation. 

Under the proposed amendments, an owner who chooses to continue to register the 

secondary engine of a crane or street sweeper under PERP would be exempt from its 

recordkeeping and reporting requirements, but would remain subject to the inspection 

and testing fees. In addition, they would, respectively, be required to comply with the 

applicable recordkeeping, reporting and other administrative requirements of the 

regulation for in-use off-road diesel vehicles and of the proposed regulation. 

C. Changes to Idling Requirements for Certain On-Road Vehicles 

Staff is proposing changes to title 13, CCR, section 2485 (ATCM to Limit Diesel-Fueled 

Commercial Motor Vehicle Idling) and section 1956.8 (Exhaust Emissions Standards 

and Test Procedures – 1985 and Subsequent Model Heavy-Duty Engines and Vehicles) 

to exempt armored cars and workover rigs from the vehicle idling limits. 

When an armored car is at a pick-up location, at least one guard must stay inside the 

vehicle. Since the environment inside of an enclosed armored car can become 

extremely uncomfortable, idling of the engine for climate control is essential to the 

health and safety of the onboard guard. For this reason, staff is proposing to add new 

section 2485(d)(2)(M) to exempt armored cars idling while providing services for which 

the vehicle was designed. 

Staff is also proposing that the idling requirements for workover rigs be amended. Staff 

is proposing to add a new provision in section 2485(d)(2)(N) to exempt workover rigs 

from the motor vehicle idling limit while they are performing the work for which the 

vehicle was specially designed. This proposal would allow a workover rig to carry out 

its specialized function when the vehicle is stationary and the engine is working 

Staff is proposing to modify the engine requirements of title 13, CCR, section 1956.8 to 

be consistent with the change proposed to the Commercial Vehicle idling ATCM for 

workover rigs and armored cars. The proposed changes to these engine requirements 

would add armored cars and workover rigs to the list of exempted vehicles in section 

1956.8(a)(6)(B). 
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XII. ENVIRONMENTAL IMPACT

This chapter discusses the potential impacts that the proposed regulation may have on 

public health and the environment, including air, water and soil. Based on our analysis, 

staff expects significant environmental benefits and does not anticipate any significant 

adverse public health or environmental impacts associated with the proposed 

regulation. 

The proposed regulation will provide significant PM and NOx emission benefits by 

accelerating the introduction of newer cleaner engines and the installation of retrofits for 

PM exhaust emissions control on existing engines. While verified DECS can have a 

fuel economy penalty, this is expected to be offset by improvements in fuel economy 

from accelerated introduction of newer engines. 

A. Legal Requirements 

The California Environmental Quality Act (CEQA) and ARB policy require an analysis to 

determine the potential environmental impacts of proposed regulations. Because the 

ARB’s program involving the adoption of regulations has been approved by the 

Secretary of Resources pursuant to Public Resources Code, section 21080.5, the 

CEQA environmental analysis requirements may be included in the Initial Statement of 

Reasons (ISOR or Staff Report) for this rulemaking in lieu of following the CEQA format 

of an Initial Study and an Environmental Impact Report or Negative Declaration. In 

addition, ARB staff will respond, in the Final Statement of Reasons for the regulation, to 

all significant environmental issues raised by the public during the public review period 

or at the Board public hearing. 

Public Resources Code section 21159 requires that the ARB’s environmental impact 

analysis include the following: 

• An analysis of the reasonably foreseeable environmental impacts of the methods of 

compliance; 

• An analysis of reasonably foreseeable mitigation measures; and 

• An analysis of reasonably foreseeable alternative means of compliance with the 

regulation. 

Compliance with the proposed regulation is expected to directly affect air quality and 

potentially affect other environmental media. Our analysis of the reasonable 

foreseeable environmental impacts of the methods of compliance is presented below. 

Regarding mitigation measures, CEQA requires the lead agency to identify and adopt 

feasible mitigation measures that would minimize any significant adverse environmental 

impacts described in the environmental analysis. 

The proposed regulation is designed to primarily reduce emissions of diesel PM – a 

toxic air contaminant – and NOx. The diesel PM reductions are needed to reduce the 

public health impacts from exposure to diesel PM as required by Health and Safety 

Code (HSC) sections 39666 and 39667, and to fulfill the goals of the October 2000 
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Diesel Risk Reduction Plan (ARB, 2000). The NOx emissions reductions are needed to 

provide the ozone and particulate matter precursor emissions reductions necessary to 

achieve attainment in those areas of the State that violate the National and State 

ambient air quality standards for ozone and particulate matter. The regulation is also 

necessary to fulfill ARB’s obligations under HSC 43013 and 43018 to achieve the 

maximum feasible and cost effective emission reductions from all mobile source 

categories, including on-road diesel engines. 

Alternatives to the proposed regulation are discussed in Chapter XVIII of this report. 

ARB staff has concluded that there are no alternative means of compliance that would 

achieve similar diesel PM and NOx emission reductions at a lower cost. 

B. Reasonably Foreseeable Environmental Impacts 

Staff has identified both benefits and potentially adverse environmental impacts of 

compliance with the proposed regulation. 

1. Statewide Air Quality Impacts 

On-road engines are major contributors to PM2.5 and ozone pollution. The proposed 

regulation will provide diesel PM and NOx emissions reductions that will have a 

substantial positive air quality impact throughout California. By reducing ambient levels 

of PM2.5 and ozone, the regulation will help with the progress towards attainment of 

National and State ambient air quality standards for PM2.5 and ozone. Significant 

health benefits will be obtained with the reductions of ambient levels diesel of PM, a 

toxic air contaminant. 

The emissions benefits of the proposed regulation are summarized in Table XII-1 below 

and discussed in more detail later in this chapter. Staff estimates that between 2010 

and 2025, as older engines are replaced with newer engines or retrofitted with diesel 

exhaust control systems, PM emissions will be reduced by an average of 2,160 tons per 

year and NOx by an average of 30,000 tons per year. 

The PM and NOx emissions reductions from the proposed regulation and the resulting 

reduction in ambient levels of these compounds will help with efforts to achieve ambient 

air quality standards for both PM2.5 and ozone in non-attainment areas of the State. 
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Table XII-1: Emission Benefits from Implementation of the Proposed Regulation 

Benefits of Regulation 

(2010 – 2030) PM NOx 

Emissions Removed 

(total tons) 34,600 480,000 

Annual Average Reductions 

(tons per year) 2,160 30,000 

a) Methodology 

The proposed regulation would initially require older vehicles to install DPFs; several 

years later, it would require replacement of that vehicle with a compliant vehicle. 

Applying the proposed compliance schedules amongst fleets requires assessing 

compliance within each inventory category by fleet size, and then assessing the fraction 

of VMT subject to low-mileage provisions. 

To assess potential compliance patterns staff evaluated previous vehicle buying 

patterns by fleets based on survey data collected, as well as the cost model developed 

for this regulation. Using these data, staff assessed the likely model year truck or bus 

that would be purchased in a given calendar year. Based on an analysis of historical 

buying patterns, the largest fleets were most likely to purchase new vehicles, even if the 

regulation does not require it -- while smaller fleets operating older vehicles were likely 

to comply by doing the minimum that the regulation requires. For example, if the 

regulation requires that a fleet purchase a 2010 compliant vehicle to replace a 2007 

non-compliant vehicle in 2021, staff assumed a smaller or older fleet would purchase a 

2010 vehicle, an average in-state fleet would purchase a 3-5 year old vehicle, and an 

out-of-state truck fleet would purchase a new vehicle. Details on these assumptions are 

provided in Appendix G. 

b) Reduction of PM and NOx Emissions 

The projected PM emissions reductions from implementation of the proposed regulation 

are presented in Table XII-2 and Figure XII-1, while the NOx emissions reductions are 

shown in Table XII-3 and Figure XII-2 

As the baseline inventory estimates show, a decline in overall PM and NOx emissions 

from on-road diesel engines is expected as the on-road fleet becomes increasingly 

dominated over time by engines that comply with existing emission regulations. 

However, this decline in emissions is not sufficient to meet ambient air quality 

standards. Without additional emissions reductions from these engines, this downward 

trend in emissions is expected to reverse and emissions are expected to rise in the 

future as the effect of growth in the population of the on-road sector surpasses the 

effect of the existing standards. 

Staff estimates that with implementation of the proposed regulation, diesel PM 

emissions will be reduced by about 13 tons per day (tpd) in 2014 and 3.5 tpd in 2023 
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relative to baseline levels. These reductions represent a 68 percent decrease in PM 

emissions in 2014 and a 33 percent decrease in 2023. Also, the projected PM emission 

rate in 2020 (6.9 tpd) will be 79 percent lower than the 2000 baseline level of 33.1 tpd. 

Therefore, while the proposed regulation comes close, but does not achieve the goal of 

the Diesel RRP of reducing diesel PM by 85 percent by 2020. It does achieve the 

maximum feasible PM emission reductions. 

Table XII-2: Statewide PM Emissions Benefits from the Proposed Regulation 

PM Emissions (tons per day) Projected Reductions Calendar 

Year Baseline With the 

Regulation (tons per day) Percent from Baseline 

2010 27.9 27.9 — — 

2014 19.0 6.1 12.8 68% 

2017 14.4 6.6 7.8 54% 

2020 12.1 6.9 5.2 43% 

2023 10.5 7.1 3.5 33% 

Figure XII-1: Projected PM Emissions With and Without the Regulation 

0

5

10

15

20

25

30

35

2008

2009

2010

2011

2012

2013

2014

2015

201620172018

20192020

2021

2022

2023

PM2.5 Tons per Day

Baseline With Regulation

The projected NOx emissions reductions from the proposed regulation are 124 tpd and 

98 tpd, for 2014 and 2023, respectively. NOx emissions would be 25 percent lower in 
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2014 and 31 percent lower in 2023 than they would be in the absence of the proposed 

regulation. 

Table XII-3: Statewide NOx Emissions Reductions from the Proposed Regulation 

NOx Emissions (tons per day) Projected Reductions Calendar 

Year Baseline With the 

Regulation (tons per day) Percent from Baseline 

2010 749 749 — — 

2014 500 377 124 25% 

2017 401 296 105 26% 

2020 346 266 79 23% 

2023 319 221 98 31% 

Figure XII-2: Projected NOx Emissions With and Without the Regulation 

0

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500

600

700

800

900

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2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

NOx Tons per Day

Baseline With Regulation

Overall, staff estimates that California registered trucks, which account for 57 percent of 

statewide truck and bus VMT, will provide roughly 91 percent of total NOx benefit, 

because those trucks tend to be older than trucks entering California from other states. 

In addition, staff found that small fleets of three trucks or fewer comprise 35 percent of 

VMT but provide nealry 50 percent of NOx benefits achieved through this regulation. 

This is because smaller fleets tend to be older than larger fleets, across all inventory 

categories. 
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2. Impact on the State Implementation Plan 

The 2007 SIP was based on the applicable version of ARB’s on-road motor vehicle 

emissions model, EMFAC2007. Staff, in support of this rulemaking, has undertaken 

comprehensive efforts to update and improve the truck inventory since the SIP was 

adopted. New data not available at the time of SIP development was used in assessing 

the costs and benefits of this statewide rulemaking. However, assessing the proposed 

regulation benefits in terms of meeting the regional SIP targets must be done with the 

SIP inventory, since the SIP inventory is the official inventory for judging SIP 

compliance. 

The 2007 SIP truck measure envisioned modernizing truck fleets operating in California 

to the equivalent of the cleanest adopted new engine (2010) standards. This proposed 

regulation meets that goal on the pace necessary to meet all the SIP target dates. 

While the quantification of benefits with the new inventory is different than with the SIP 

inventory, the difference is in accounting not rule effectiveness. A primary reason for 

the difference is that new data shows there is more travel by newer, cleaner out-of-state 

trucks than previously estimated in EMFAC2007. As a result, fewer benefits can be 

attributed to the proposed regulation for out-of-state trucks because they will already 

employ 2010 compliant engines. The proposed regulation benefits are primarily 

attributed to the modernization of in state fleets that are older and dirtier. In short, the 

proposed regulation accomplishes the modernization of truck fleets as envisioned in the 

SIP. 

Table XII-4 and Table XII-5 show, using the regional SIP inventories, the proposed 

regulation benefits compared to the expected reductions. The SIP targets in these 

tables refer to the fleet modernization portion of the truck SIP measure. The second part 

of the SIP measure for trucks, a program to address excess emissions, will be 

developed separately. The proposed regulation meets or exceeds the combined NOx 

and PM2.5 SIP fleet proposed regulation targets in both the South Coast and San 

Joaquin Valley for all years. In 2014, in the South Coast, the SIP target is met with 

slightly more PM2.5 reductions and slightly less NOx than expected. The PM2.5 

modeling used in the South Coast Air Quality Management District SIP shows that 

direct PM2.5 emission reductions are relatively more effective in reducing ambient 

particulate levels than are NOx reductions. As shown in Table XII-4 the proposed 

regulation achieves 60 tons per day of NOx in 2014 and the equivalent of six tons per 

day of NOx from the extra PM2.5 reductions that exceed the PM2.5 SIP target. The SIP 

also included reductions in 2020 to support attainment in regions downwind of South 

Coast and the San Joaquin Valley. These 2020 goals are met for both regions. 
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Table XII-4: South Coast SIP Emission Reduction Targets for Trucks 

NOx (tpd in SIP inventory) PM2.5 (tpd in SIP inventory) 

Calendar Year SIP Target for 

Rule1 Rule SIP Target for Rule1 Rule 

2014 662 603

 plus 6 

equivalent tons 2.3 3.53

2020 23 27 -- -- 

2023 15 22 -- -- 

1

 The truck measure reductions estimated in the SIP include the benefits of programs to reduce excess 

emissions. The numbers presented here are the SIP goals for the modernization rule only. 

2

 This target represents expected benefits from the enhanced truck measure designed to provide 

additional reductions in 2014 for South Coast PM2.5 attainment and to accelerate ozone attainment in 

the San Joaquin Valley. 

3

 SIP compliance assessment includes agricultural truck compliance option. 

Table XII-5: San Joaquin SIP Emission Reduction Targets for Trucks 

NOx (tpd in SIP inventory) PM2.5 (tpd in SIP inventory) 

Calendar Year SIP Target for 

Rule1 Rule SIP Target for Rule1 Rule 

2014 48 66 2.5 4.3 

2017 492 493 -- -- 

2020 17 29 -- -- 

2023 8 23 -- -- 

1

 The truck measure reductions estimated in the SIP include the benefits of programs to reduce excess 

emissions. The numbers presented here are the SIP goals for the modernization rule only. 

2

 This target represents expected benefits from the enhanced truck measure designed to provide 

additional reductions in 2014 for South Coast PM2.5 attainment and to accelerate ozone attainment in 

the San Joaquin Valley. 

3

 SIP compliance assessment includes agricultural truck compliance option. 

3. Potential Negative Impacts 

Staff has identified two potential negative impacts resulting from the potential use of 

catalyzed DPFs to comply with the proposed regulation. They are: 1) increased NO2

emissions resulting in increased NO2 exposure, and 2) the need to manage the 

hazardous ash that accumulates on the filter. 

a) Increased Nitrogen Dioxide Emissions with Passive Catalyzed Diesel 

Particulate Filters 

Unlike active diesel particulate filters, most catalyzed diesel particulate filters (CDPF) 

form NOx as part of their normal operation. The CDPF works by mechanical filtration of 

PM from the exhaust through a ceramic or metallic filter followed by oxidation of the 

captured PM – mostly elemental carbon particles – to CO2 which is released to the 

atmosphere. The oxidizing agent for this process (filter regeneration) is NO2 which is 
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produced through the catalytic oxidation of the nitric oxide (NO) formed in the engine 

combustion process. 

Typically, more NO2 is created than is actually used during the regeneration process, 

and the excess is emitted. Emissions measurements have shown an increase in the 

NO2 fraction of NOx emissions (NO plus NO2) from heavy-duty diesel vehicles equipped 

with passive catalyzed diesel particulate filters even though total NOx emissions remain 

approximately the same. The NO2 to NOx ratios downstream from a CDPF could range 

from 20 to 70 percent, depending on factors such as the DPF systems, the sulfur level 

in the diesel fuel, and the duty cycle (DaMassa, 2002). On average, for diesel engines 

not equipped with a CDPF, about 7 percent of the emitted NOx is in the form of NO2

(ARB, 2006). 

The ARB’s Verification Procedure sets limits for secondary emissions from verified 

diesel emission control systems. The limit on NO2 emissions is intended to limit 

increases in ambient NO2, secondary nitrate PM, and ozone, and adverse public health 

impacts. The regulation allows a maximum NO2 increase equivalent to 30 percent of 

the total baseline NOx. Beginning January 1, 2009, the maximum increase will be 

reduced to 20 percent. Chapter VII discusses the impact of this new limit on currently 

verified DECS. 

Higher NO2 emissions will result in a very small increase in ambient levels of NO2 and 

ozone – pollutants associated with adverse health effects including respiratory 

symptoms, cardio-respiratory hospital admissions, and reduced lung function 

(ARB, 2007a). Currently, all of California is in compliance with the State 1 hour ambient 

NO2 air quality standard, often by a wide margin. Staff analyzed the impact on microscale exposures such as at schools where school buses idle and on freeways with 

heavy diesel traffic. The analysis showed no violations of the 1 hour standard 

(ARB 2006). The anticipated reductions in NOx, and associated ozone and ambient 

NO2 from the proposed regulation, are expected to more than offset any increases in 

ozone formation from increased NO2 emissions from CDPFs. 

b) Ash Management 

The PM trapped by a DPF includes solid carbonaceous material or soot, semi-volatile 

organic matter (SOF), and inorganic solid particles. During the regeneration of the DPF, 

the captured soot and other combustible organic matter are oxidized to carbon dioxide 

and water, but the inorganic material is not typically combusted. Instead, it accumulates 

in the DPF as an ash. The DPF provides an environmental benefit by filtering metallic 

ash from the exhaust, but for effective operation of the DPF, the accumulated ash, 

which could be classified as a hazardous waste, must be periodically removed from the 

filter. 

The principal sources of ash are fuel additives, engine lubricating oil, salts from 

environmental air, and motor wear. It primarily consists of oxides, sulfates and 

phosphates of iron, calcium, and zinc. Depending on the concentration of zinc, the ash 

may be classified as a hazardous waste. Title 22, CCR, section 66261.24, establishes 
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two limits for zinc in a waste: 250 milligrams per liter for the Soluble Threshold Limit 

Concentration and 5,000 milligrams per kilogram for the Total Threshold Limit 

Concentration. The presence of zinc at or above these levels would cause a sample of 

ash to be characterized as a hazardous waste. 

According to California law, it is the generator’s responsibility to determine whether or 

not their waste is hazardous. This, in general, would require a chemical analysis of the 

collected ash sample to determine the zinc content. Applicable California regulations 

concerning the management and disposal of hazardous waste are contained in title 22 

of the California Code of Regulations and are enforced by the Department of Toxic 

Substances Control (DTSC). Owners planning to dispose of ash from a DPF should 

contact both the manufacturer of the DPF and DTSC for advice on waste management. 

They should also consult with local environmental agencies to determine acceptable 

disposal methods. Diesel fuel ash is not listed as a hazardous waste by EPA in the 

Code of Federal Regulations (40 CFR Part 261). Federal regulations also conditionally 

exempt small quantity generators who generate less than 220 pounds per month of 

solid waste from federal hazardous waste regulations. 

The amount of ash collected from a filter during a typical cleaning procedure is relatively 

small. For example, ARB reports that the amount of material collected from a single 

filter in a single cleaning procedure is in the range of 10-20 grams of ash. ARB 

extrapolated this ash collection amount to 10-20 kg (22-44 pounds) of ash collected per 

year for a fleet of 1,000 transit buses (ARB, 2002). 

Most of the ash is formed from the inorganic materials in engine oil, particularly from 

zinc-containing additives necessary to control acidification of engine oil – due in part to 

sulfuric acid derived from sulfur in diesel fuel. The need for acid neutralizing additives in 

engine oil has decreased as the sulfur content of diesel fuel has decreased. American 

Petroleum Institute (API) CJ-4, which was introduced in October 2006, limits the oil's 

sulfated ash, phosphorus, and the amount of zinc dithiophosphate-containing detergent 

in the diesel engine oil to insure adequate service life of the DPF. It reduces ash 

accumulation rates in DPFs and prevents premature plugging 

4. Environmental Justice and Neighborhood Impacts 

The objectives of ARB’s statewide regulatory programs are better air quality and 

reduced health risk for all residents throughout California. The Board has a policy that 

community health and environmental justice (EJ) concerns be addressed in all of ARB’s 

regulatory programs. Chapter III of this Staff Report gave an overview of ARB’s 

commitment to integrating environmental justice in all its activities. 

With implementation of the proposed regulation, PM and NOx emissions as well as 

associated cancer risks and other health impacts will decrease over time as on-road 

vehicle fleets become cleaner. This is consistent with the ARB’s EJ policy of reducing 

exposure to air pollutants and reducing the adverse impacts from toxic air contaminants 

in all communities, including low-income and minority communities. Although vehicles 
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would be cleaned up on different schedules, staff expects emissions to decline in all 

areas. 

C. Health Benefits Analysis 

The emissions reductions obtained with implementation of this proposed regulation will 

result in lower ambient PM and ozone levels and reductions in public exposure to these 

pollutants. The potential health impacts of PM and NOx emissions from on-road 

engines and the consequent need for emissions reductions were discussed in Chapter 

IV. This section describes the statewide health benefits and the benefits to the targeted 

southern California urban study area of reducing emissions of PM and NOx from 

engines subject to the proposed regulation. It also provides the societal cost savings of 

the proposed regulations. 

1. Reduced PM and NOx Emissions 

a) Statewide Non-Cancer Health Benefits 

The proposed regulation is projected to reduce PM2.5 emissions from heavy-duty diesel 

vehicles statewide by approximately 34,600 tons between 2010 and 2025. The 

projected NOx emission reduction over the same time period is 480,000 tons. The 

effect of reducing these emissions would be a reduction in the prevalence of the 

diseases attributed to diesel PM, reduced incidences of hospitalizations, and prevention 

of premature deaths. 

Staff quantified the statewide cumulative impact of the total emissions removed from 

2010 through 2025 through the implementation of the proposed regulation. The 

analysis used the same non-cancer health endpoints reported in Chapter IV for the 

impact of the 2008 baseline emissions. Appendix E provides a description of the 

methodology used to estimate the health benefits. 

The estimates reported in Table XII-6 demonstrate that the health benefits of 

implementing the proposed regulation are substantial. Staff estimates that the 

cumulative emissions reductions from 2010 to 2025 would result in approximately 

9,400 fewer premature deaths, 1,100 fewer hospital admissions due to respiratory 

causes, 1,200 fewer hospital admissions due to cardiovascular causes, 150,000 fewer 

cases of asthma-related and other lower respiratory symptoms, 12,000 fewer cases of 

acute bronchitis, 950,000 fewer work loss days, and 5,400,000 fewer minor restricted 

activity days. Table XII-6 also shows the range for each estimated benefit. 

The analysis of the impact of the regulation includes the benefits of reductions of direct 

diesel PM and indirect diesel PM – nitrates formed from precursor NOx emitted by 

diesel engines. The impacts of direct and indirect sources of PM are listed separately in 

Table XII-6. The health benefits of reducing NOx as a precursor to ozone are not 

included in the estimates. Because only a subset of health outcomes was considered, 

the estimates are conservative. 
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Table XII-6: Total Health Benefits Associated with Reductions in Emissions from 

the Implementation of the On-Road Truck and Bus Regulation (2010-2025)* 

Endpoint Pollutant Number of Cases 

(Mean) Range (95% C.I.) 

PM 3,300 990 – 6,000 

Premature Mortality NOx 6,100 1,800 – 11,000 

Total 9,400 2,800 – 17,000 

PM 64 23 – 110 

NOx 1,000 580 – 1,500 Hospital admissions 

(Respiratory) Total 1,100 600 – 1,600 

PM 270 140 – 400 

NOx 960 590 -1,400 Hospital admissions 

(Cardiovascular) Total 1,200 730 – 1,800 

PM 53,000 20,000 – 85,000 

NOx 96,000 39,000 – 150,000 Asthma & Lower 

Respiratory Symptoms Total 150,000 59,000 – 240,000 

PM 4,400 0 – 9,600 

Acute Bronchitis NOx 7,600 0 – 16,000 

Total 12,000 0 – 26,000 

PM 330,000 280,000 – 380,000 

Work Loss Days NOx 620,000 520,000 – 710,000 

Total 950,000 800,000 – 1,100,000 

PM 1,900,000 1,600,000 – 2,300,000 

NOx 3,500,000 2,900,000 – 4,200,000 Minor Restricted 

Activity Days Total 5,400,000 4,500,000 – 6,500,000 

* Health effects from primary and secondary PM are labeled PM and NOx, respectively. The sum of PM 

and NOx impacts may not equal the total given due to rounding. Estimates for premature deaths are 

based on an updated relative risk of 10% per 10 μg/m3 change in long term PM2.5 exposure, with a 

confidence interval of 3% - 20% (ARB, 2008). 

b) Local Non-Cancer Health Benefits 

On a local level, as part of the Commerce Study, staff also estimated these same health 

benefits between 2010 through 2020. Such benefits would be a subset of the statewide 

numbers reported above; that is, these benefits are due only to the reduction in 

emissions expected from implementation of the proposed regulation within the 

Commerce study area. Statewide, much greater benefits are expected to be realized as 

reported above. The anticipated benefits in and around the City of Commerce are: 

• 78 avoided premature deaths ( 20 to 130, 95 percent CI) 

• 60 avoided hospital admissions – respiratory and cardiovascular (24 to 90, 95 

percent CI) 

• 2,600 avoided asthma attacks (1,000 to 4,000, 95 percent CI) 
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• 220 avoided acute bronchitis ( 0 to 48, 95 percent CI) 

• 14,700 avoided work loss days (11,500 to 16,500, 95 percent CI) 

• 80,000 avoided minor restricted activity days (70,000 to 93,000, 95 percent CI) 

2. Potential Localize Cancer Risk Reduction 

On a local level, using the results from the Commerce study, staff’s analysis estimates 

that risk levels in and around the city of Commerce will be reduced by over 80 percent, 

to less than 70 in a million, by 2015. However, localized cancer risks will begin to 

increase as growth begins to surpass the reductions realized by the regulations, with 

the predicted remaining cancer risk in the 2020 timeframe rising to about 75 in a million 

in and around the city of Commerce. As vehicle miles traveled in the future continues, 

this increase in cancer risk will continue, albeit at a significantly lower rate of increase 

than would occur in the absence of the proposed regulation. Appendix E provides a 

more detailed description of the methodology and results. 

3. Benefits of Reduced Ambient Ozone Levels 

Emissions of NOx and ROG are precursors to the formation of ozone in the lower 

atmosphere. On-road diesel engines contribute a substantial fraction of ozone 

precursors, particularly NOx, statewide. Therefore, reductions in NOx from on-road 

diesel engines are a considerable contribution to California’s efforts to reduce exposure 

to ambient ozone. Controlling emissions of ozone precursors reduces the prevalence of 

the health effects associated with ozone exposure, such as coughing, chest tightness, 

inflammation and irritation of the respiratory tract, worsening of wheezing and other 

asthma symptoms, and reduced lung function, and would reduce hospital admissions 

and emergency visits for respiratory problems. 

4. Economic Benefit 

The proposed regulation would provide significant economic benefits as well. During 

the 2010 to 2025 period, the estimated statewide cumulative economic benefits from the 

proposed regulation is $69 billion using a 3 percent discount rate or $48 billion using a 

7 percent discount rate. ARB follows U.S. EPA practice in reporting results using both 

3 percent and 7 percent discount rates. A large portion of the monetized benefits 

results from avoiding premature death. The estimated benefits from avoided morbidity 

are approximately $510 million with a 3 percent discount rate and nearly $350 million 

with a 7 percent discount rate. Approximately 68 percent of the benefits are associated 

with reduced PM from NOx emissions, and the remaining 32 percent from direct PM 

emissions. Appendix E discusses the methodology staff used to monetize the value of 

avoiding the adverse health impacts using valuations compiled from ARB and U.S.EPA 

publications, updated to 2007 dollars. 
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D. Climate Change Impacts 

This section provides a general discussion of the impact of the projected emissions 

reductions on climate change and provides an estimate of the impact based on changes 

in CO2 emissions with implementation of this regulation. 

1. Greenhouse Gases 

The most important class of climate forcing agents responsible for global warming are 

greenhouse gases (GHG) which are predominantly comprised of CO2, methane (CH4) 

and nitrous oxide (N2O). Other GHGs include water (H2O), CO and ozone. These 

gases are known as GHGs, due to their transparency to high frequency solar radiation 

and their opacity to low frequency infrared radiation emitted from the Earth’s surface. 

The gases differ in their atmospheric warming potential, and as a result, the contribution 

of each gas is determined as equivalent CO2 emissions using conversion factors 

approved by the Intergovernmental Panel on Climate Change. For example, methane 

has 21 times the warming potential of carbon dioxide and N2O has 310 times the 

warming potential of CO2. 

In evaluating the potential GHG emissions changes and their impacts on climate 

change, it is relevant to examine changes in CO2 emissions associated with fuel 

economy impacts, as well as impacts of particle and aerosol formation and emissions. 

a) Fuel Economy 

A vehicle owner who complies with the regulation by retrofitting the vehicle with a DPF 

could potentially experience a decrease in the vehicle’s fuel economy of about 2 

percent. However, as the fleet is modernized to comply with the regulation, SCR is 

expected to replace EGR as the primary NOx emissions control technology. SCR for 

2010 model year engines permits operation of the engine at more optimal combustion 

temperatures to provide better power and fuel efficiency improvements, as well as lower 

PM generation. 

The expected improvements in fuel economy from the use of SCR, estimated 3 to 5 

percent, would offset the potential climate change impacts of the widespread installation 

of DPFs on the overall fuel economy of the fleet. 

Staff expects fuel economy to improve over time with the introduction of engines 

meeting the 2010 emission standard and as a result, CO2 emissions will increase at a 

slower rate than the predicted increase in VMT. Staff does not anticipate a significant 

reduction of CO2 emissions as a result of the proposed regulation (Figure XII-3). 
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Figure XII-3: Statewide CO2 Baseline and With Regulation Emissions 

0

20000

40000

60000

80000

100000

120000

140000

160000

2008

2009

2010

2011

2012

2013

2014

20152016

2017

2018

2019

2020

2021

20222023

CO2 Tons per Day

Baseline With Regulation

The proposed regulation would also reduce emissions of black carbon – a component of 

diesel PM and a likely contributor to global warming – which would further reduce 

climate change impacts attributed to the overall impact on fuel economy. 

b) Net Effect on Greenhouse Gases 

The overall impact of the regulation on climate change would be negligible. Staff 

expects a negligible decrease in CO2 emissions of less than one percent after taking 

into account the fuel economy benefit of SCR for 2010 and later model year engines, 

and the relatively small CO2 increase associated with the fuel economy penalty for 

DECS installed to comply with the regulation. 

In assessing the climate change impact of the proposed regulation, staff examined only 

the direct emissions from operation of the vehicles. In addition to CO2, on-road diesel 

engines emit significant amounts of at least two pollutants associated with climate 

change – black carbon and ozone-forming NOx. However, it is difficult at this time to 

estimate the impacts of reductions of these pollutants on climate change since there is 

no global warming potential yet assigned to black carbon. 

2. Aerosols 

Particles, especially those with diameters smaller than 1 micron (μm), can affect the 

earth’s temperature and climate by altering the radiative properties of the atmosphere. 
-167- 

“Reflective aerosols” will scatter solar radiation so that a substantial portion of the 

radiation incident to the Earth’s troposphere is returned to space, thereby cooling the 

climate. Examples of these are sulfates, nitrates, and organic carbon particles. 

“Absorbing aerosols” will absorb solar radiation, transfer the energy to the atmosphere, 

and prevent sunlight from reaching the ground. These aerosols warm the atmosphere, 

but cool the surface. Black carbon aerosols, or soot, formed by incomplete combustion 

are absorbing aerosols and cause a positive climate forcing of uncertain magnitude. 

Current investigations indicate that black carbon and associated organic matter play a 

major role in climate change, but this role has not been quantified reliably. Modeled 

estimates for radiative forcing by black-carbon-containing aerosols range widely. It may 

be the second or third largest individual warming agent, following CO2 and perhaps 

methane (Bond and Sun, 2005). 

Since diesel PM is composed largely of black carbon and associated organic matter, the 

diesel PM emissions reduction obtained with the proposed regulation would have a 

positive climate change impact by reducing the black carbon component of global 

warming. Also, because the lifetime in the atmosphere for most black carbon is short 

compared to CO2, the control of black carbon emissions can bring an immediate 

environmental benefit compared to the slower response to CO2 emissions controls. 

3. Ozone Precursors 

It is estimated that tropospheric ozone has had the third largest impact on radiative 

forcing (1750 to present) of all GHGs. Changes in tropospheric ozone are due to 

anthropogenic increases in the emissions of ozone precursors – NOx and VOCs. 

However, the effect of reducing these precursors is still uncertain, as there are no 

agreed-upon methods for estimating the Global Warming Potential of ozone precursors. 

Also, ozone production leads to the formation of particulate nitrate and secondary 

organics which enhance cooling. However, there are no methods for accounting for the 

indirect effects of changes in tropospheric chemistry. Ozone is short lived in the 

troposphere (an average lifetime on the order of weeks) and is typically treated as a 

regional pollutant with direct and indirect climate effects that vary considerably by 

location. 

4. Alternative Fuels 

The proposed regulation gives credit for the use of hybrid electric and alternative fuel 

vehicles and systems to replace diesel vehicles. This provision of the rule could have a 

positive impact on climate change to the extent that it is effective in encouraging owners 

to purchase low-GHG vehicles or use low GHG fuels where they are cost effective 

alternatives to conventional diesel vehicles or fuel. This will result in a clear GHG 

advantage from the need for reduced power generation and fuel production. 

For electric vehicles, there are greenhouse gas implications in battery manufacturing, 

replacement and disposal. However, on a lifecycle basis, electric vehicles have lower 

associated emissions than diesel vehicles (Delucchi, 2005). Over the longer term, 
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expanding the use of electric vehicles would provide the benefit of zero tailpipe 

emissions, and reduced climate change impacts. 

E. Welfare Impacts 

In addition to the public health effects of fine particulate pollution, fine particulates 

including sulfates, nitrates, organics, soot, and soil dust contribute to regional haze that 

impairs visibility. 

In 1999, the U.S. EPA promulgated a regional haze regulation that calls for states to 

establish goals and emission reduction strategies for improving visibility in 156 

mandatory Class I national parks and wilderness areas. California has 29 of these 

national parks and wilderness areas, including Yosemite, Redwood, and Joshua Tree 

National Parks. Reducing diesel PM from diesel-fueled on-road vehicles would help 

improve visibility in these Class I areas. 

F. Reasonably Foreseeable Mitigation Measures 

ARB staff has concluded that no significant adverse environmental impacts should 

occur from adoption of and compliance with the proposed regulation. Therefore, no 

mitigation measures would be necessary. 

G. Alternative Means of Compliance with the Proposed Regulation 

Alternatives to the proposed regulation are discussed in Chapter XVIII of this report. 

ARB staff has concluded that the proposed regulation provides the most effective and 

least burdensome approach to reducing exposure of children and the general public to 

diesel PM and other air pollutants emitted from on-road diesel-fueled engines. 

H. References 

ARB, 2002. Air Resources Board. Initial Statement of Reasons: Proposed Modification 

to the Public Transit Bus Fleet Rule and Interim Certification Procedures for the HybridElectric Urban Transit Buses. Appendix F – Staff Analysis of PM Emission Reductions 

and Cost-Effectiveness. September 6, 2002. 

http://www.arb.ca.gov/regact/bus02/bus02.htm

ARB, 2006. California Air Resources Board. Proposed Regulation for the Verification 

Procedure for In-Use Strategies to Control Emissions from Diesel Engines. Staff 

Report, Initial Statement of Reasons for Proposed Rulemaking. March 29, 2002. 

ARB, 2007a. California Agency, Air Resources Board and Office of Environmental 

Health Hazard Assessment. Review of the Ambient Air Quality Standard for Nitrogen 

Dioxide. Staff Report January 5, 2007. http://www.arb.ca.gov/research/aaqs/no2-

rs/no2-doc.htm#TechSuppDoc
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ARB, 2008. California Air Resources Board. Methodology for Estimating the Premature 

Deaths associated with Long-term Exposure to Fine Airborne Particulate Matter in 

California. http://www.arb.ca.gov/research/health/pm-mort/pm-mort.htm

Bond, T.C., Sun, H. Can Reducing Black Carbon Emissions Counteract Global 

Warming? Environ. Sci. Technol. 2005, 39:5921-5926. 

DaMassa, J. California Air Resources Board. Presentation: Air Quality Effects of TrapRelated Emissions (Updated); February 6, 2002. 

Delucchi, 2005. A Multi-Country Analysis of Lifecycle Emissions from Transportation 

Fuels and Motor Vehicles. Mark A. Delucchi, Institute of Transportation Studies, 

University of California, Davis. UCD-ITS-RR-05-10. 
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XIII. COST SUMMARY AND METHODOLOGY 

This chapter discusses the methodology staff developed to estimate the costs 

associated with the proposed regulation. These costs relate to the installation and 

maintenance of verified DECS and the early replacement of vehicles to newer vehicles 

(beyond what fleets have historically done). To conduct this analysis, staff developed a 

cost model to estimate the capital expenditures of normal vehicle replacement 

compared to the capital expenditures required to comply with the proposed regulation. 

The cost model examines actual individual company fleet actions each year between 

2009 and 2030, with and without the proposed regulation. The results for each fleet 

included in the cost model are then scaled up to reflect the impacts on the statewide 

heavy-duty diesel vehicle population, including out-of-state vehicles operating in 

California. 

A. Legal Requirements 

Sections 11346.3 and 11346.5 of the Government Code require state agencies to 

assess the potential for adverse economic impacts on California business enterprises 

and individuals when proposing to adopt or amend any administrative regulation. The 

assessment shall include a consideration of the impact of the proposed regulation on 

California jobs, business expansion, elimination, or creation, and the ability of California 

businesses to compete. 

State agencies are also required to estimate the cost or savings to any state or local 

agency and school districts in accordance with instruction adopted by the Department of 

Finance. This estimate is to include any nondiscretionary costs or savings to local 

agencies and the costs or savings in federal funding to the state. 

B. Methodology for Estimating Costs 

1. Overview 

The cost and economic impacts of this regulation are based on the anticipated 

compliance paths of the affected statewide fleets. To perform this analysis, staff 

estimated the cost that fleets are already incurring under their normal vehicle 

replacement practices. Staff then estimated the costs that fleets would incur to meet 

the requirements of the proposed regulation. The difference between these two 

numbers is the regulatory costs of staff’s proposal. These costs have been estimated 

for the years between 2010 and 2030. 

Staff developed the ARB On-Road Compliance Model (cost model) to estimate the 

capital expenditures of normal vehicle replacement during the analysis period compared 

to the capital expenditures required to comply with the proposed regulation over the 

same period. Using actual fleet data reported in the ARB fleet survey on over 13,000 

vehicles, the costs to the statewide fleets were calculated by predicting and evaluating 

the compliance paths for real individual fleets using the cost model. 
-172- 

Staff used the cost model to analyze over 6,700 vehicles from 688 actual individual 

company fleets for each calendar year from 2009 to 2030, both with the regulation and 

without the regulation. The fleets evaluated varied by fleet age, vehicle type and weight 

class, and provided a representation of in-state and out-of-state fleets operating in 

California. The analysis determined the costs beyond those of estimated normal vehicle 

replacement; all costs calculated are additional costs fleets would incur by complying 

with the regulation. 

In addition to capital costs, various annual operational and maintenance costs are 

attributable to the regulation. Operational and maintenance costs associated with NOx 

and PM controls would include annual PM filter cleaning expenses, changes in fuel 

economy, urea costs for SCR systems, and costs associated with regeneration of active 

PM systems. Potential cost savings include fuel economy improvements with 

replacement of older vehicles with newer vehicles. In addition, companies would incur 

annual reporting costs when required to report to ARB. These annual costs were 

modeled separately and added to the capital cost estimates to arrive at an overall cost 

estimate. The cost and economic methodology is described in more detail in 

Appendix J. 

a) Fleet Data Collection Approach 

First, the cost estimate of the proposed regulation was developed through the use of a 

number of sources of data. Staff met with several individual companies and obtained 

information about their normal business practices. Staff also conducted a detailed fleet 

information survey with participation by fleet organizations and individual stakeholders. 

An ARB fleet survey collected information from fleets throughout the state regarding 

their company’s business operations, such as the fleet’s primary business use 

categories and number of vehicles in each fleet. The survey data also included vehicle 

specific information for heavy-duty diesel vehicles, including model year, weight ratings, 

and annual mileage data. See Appendix J for summary information obtained by the 

survey regarding reported counts by vehicle body type and by fleet size and age. 

b) Vehicle Replacement 

Heavy-duty diesel engines are extremely durable and can operate 750,000 to 1,000,000 

miles before needing to be rebuilt. Although there are exceptions, few fleets operate 

vehicles significantly above 1,000,000 miles because repairs at this age often exceed 

the value of the vehicle and the loss in reliability adds indirect costs for most 

businesses. 

Normal vehicle replacement practices are dependent on a number of factors, but in 

general are best correlated to annual miles traveled and how a vehicle is used. Fleets 

with vehicles travelling over 100,000 miles per year generally have vehicle replacement 

rates that are much higher than fleets with vehicles averaging less than 20,000 miles 

per year. For example, a long haul trucking operation that averages well over 120,000 

miles per year may replace all of their vehicles with new vehicles in a 3 to 7 year period. 

In contrast, a less than truckload carrier who may average 70,000 miles per year may 
-173- 

normally buy 3 year old vehicles and keep them for 10 years, and a local construction 

fleet may average 20,000 miles per year and purchase a range of new and used 

vehicles and will often keep them for over 20 years. 

Statewide emission inventory data includes vehicle counts by model year for various 

fleet population groups (such as in-state vehicles, out-of-state vehicles, etc.). The age 

distribution of a population group provides an indication of how long vehicles remain in 

those groups, how they might transfer between groups and the ages at which they are 

retired. 

As shown below in Figure XIII-1, very few heavy heavy-duty vehicles remain in the 

statewide fleet after 25 years; only 3.4 percent of the tractors, 2.2 percent of the single 

(non-tractors) and 0.23 percent of the CA IRP vehicles are expected to remain in the 

fleet with an age over 25 years. Staff used the capital cost model to reflect these 

differences in normal purchase practices to better understand the economic impacts on 

a wide range of businesses and industry groups. 

Figure XIII-1: In-state Heavy-Heavy Duty Vehicle Age Distribution 

2. Capital Cost Inputs 

a) Vehicle Prices and Replacement Costs 

New and used vehicle prices were used as inputs to model company fleet operations for 

a range of vehicle types and ages. Staff developed price curves for over 50 vehicle 

body types by using for-sale vehicle price data downloaded from Truckpaper.com and 

other online sources. Some example price curves are shown in Figure XIII-2 below. 

Staff also confirmed this data with data from the National Automobile Dealers 

Association (NADA) that the “for sale” vehicle price information collected compared 

0.00%

2.00%

4.00%

6.00%

8.00%

10.00%

12.00%

-1

1

3

5

7

9

11

13

15

17

19

21

23

252729

Vehicle Age

% of Vehicle Population

CAIRP Vehicles

Single Unit Trucks
-174- 

favorably for a conventional tractor. However, NADA data was not used in staff’s 

analysis because the range of vehicle ages and body type configurations was limited, 

and staff believes the Truckpaper.com data is more appropriate. While heavy heavyduty vehicles regularly cost more than most medium heavy-duty vehicles, prices for all 

vehicle types decline fairly quickly with vehicle age. 

Figure XIII-2: Example Vehicle Prices (in thousands of dollars) 

Staff also assessed whether a vehicle body type could be transferred to a new cab and 

chassis, and what the costs of the body transfer would be. If a body transfer is feasible 

and costs less than a replacement vehicle, the estimated transfer costs for the truck 

body was included, in addition to the cab and chassis price. If it was less costly to 

replace a vehicle instead of transferring the body to a new cab and chassis, the 

replacement vehicle cost was used. The vehicle price data and body transfer costs 

used in the cost model are provided in Appendix J. 

b) PM Filter Capital Costs 

Staff determined PM filter cost inputs for the cost model based on data received from 

internal and external sources, and is shown in Table XIII-1. Research included 

reviewing data developed for other ARB regulatory efforts, evaluating data collected 

through ARB’s Carl Moyer program, and through discussions with local air districts, 

emission control installers and dealers, and various stakeholder groups (such as the 

non-profit organization Cascade Sierra Solutions). The cost model assumes passive 

filters would be used for post-1993 model year vehicles and that active filters would be 

used for pre-1994 model year vehicles. 

Conventional Truck Without Sleeper

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Vehicle Age

Price (thousands of $)

GVRW > 33,000 lbs

Flatbed Truck

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Vehicle Age

Price (thousands of $)

GVRW < 33,001 lbs

Cab & Chassis Truck

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Vehicle Age

Price (thousands of $)

GVRW < 33,001 lbs

Dry Van

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Vehicle Age

Price (thousands of $)

GVRW > 33,000 lbs
-175- 

Table XIII-1: PM Filter Costs 

Type of Vehicle Passive Filter Active Filter 

Medium Heavy-Duty $11,000 $15,000 

Heavy Heavy-Duty $12,000 $15,000 

Although no action would be required if a PM control device were not available for a 

particular vehicle, staff conservatively modeled cost assuming that PM filters would be 

available for all vehicles. Annual operating and maintenance costs associated with the 

use of exhaust after treatment devices were estimated, and are discussed later. 

c) Other Capital Costs 

Staff also estimated a loss in real value for vehicles covered by the proposed regulation. 

This estimate is dependent on a number of factors, such as the need for modifications 

to a vehicle and the need to transport a non-compliant vehicle out-of-state for resale. 

Staff estimates that, on average, this cost would not exceed $5,000 per vehicle for 

heavy heavy-duty vehicles, $2,000 for medium heavy-duty vehicles, and $1,000 for 

interstate vehicles. This estimate is conservative, as costs should be significantly lower 

for most tractors, as no vehicle modifications are required for most of these vehicles to 

be used outside of California. 

In addition, new engines manufactured in 2010 will be considerably cleaner than their 

predecessors and are likely to cost more than those currently being produced. Staff 

estimates that engines manufactured after 2009 will typically have SCR, which may 

increase the price of new and used vehicles by up to $5,000 for heavy heavy-duty 

vehicles and $2,500 for medium heavy-duty vehicles. Though the majority of vehicle 

manufacturers will be using SCR emission control devices for engines manufactured in 

2010, some manufacturers have indicated they do not plan to use SCR. Engine 

manufacturers that plan to include SCR in their 2010 engines have indicated an 

expected 3 to 9 percent fuel economy improvement which would offset any increased 

cost for their vehicles very quickly. 

Annual operating and maintenance costs, including changes in fuel economy, urea 

supply, annual filter cleanings, reporting and other ongoing costs are estimated 

separately from the capital investment costs and are discussed later. Other costs that 

are included in the staff’s analysis include California state sales taxes of 8 percent on 

used and new vehicle purchases, and federal excise taxes of 12 percent on new vehicle 

purchases. 

3. Fleet Cost Model 

The cost model uses Microsoft Access and Visual Basic to model normal vehicle 

replacement, compliance strategies and the resulting costs for fleets subject to the 

proposed regulation. 
-176- 

a) Modeling Normal Vehicle Replacement 

To determine the baseline fleet costs without the regulation, the cost model calculates 

an average normal vehicle replacement rate for each company’s fleet to reflect its 

normal business practice. The normal replacement rate is a function of the fleet age 

and the age of the replacement vehicle, and will vary for different fleets. For example, a 

fleet with an average age of 10 years that purchases new vehicles and keeps them for 

20 years would have an average replacement rate of five percent per year. Whereas a 

fleet with the same average age that normally purchases 5 year old vehicles and keeps 

them for 10 years would have an average replacement rate of 10 percent per year. The 

replacement rate is calculated per Equation XIII-1 below. 

Equation XIII-1: Replacement Rate = 1 / ((2*Fleet Average Age) - Vehicle 

Purchase Age) 

Staff used the fleet survey responses to determine the normal vehicle replacement ages 

for 688 fleets. An average replacement vehicle age was calculated for each average 

fleet age group, by fleet population group, as shown in Table XIII-2 below. 

Table XIII-2: Average Vehicle Replacement Age by Average Fleet Age Group 

Average Vehicle Replacement Age (Year) 

Average Fleet Age 

Group (Years) CA IRP 

In-state 

Tractor HHD 

In-state 

NonTractor HHD 

In-state 

MHD 

0 to 3 N/A (0.92) 0.00 0.00 

>3 to 6 1.05 (0.22) 1.00 0.01 

>6 to 10 1.50 1.88 1.79 1.57 

>10 to 13 2.93 3.33 2.00 1.39 

>13 to 16 5.97 8.02 6.20 5.02 

>16 to 20 N/A 8.19 9.71 8.21 

>20 N/A 14.36 11.94 7.14 

Because new model year vehicles can be purchased in the prior year, a new vehicle 

can have a purchase age of -1 (for example, a 2010 model year vehicle can be 

purchased in 2009). The CA IRP fleets tend to replace vehicles more quickly than the 

other in-state fleets, and in doing so will purchase newer vehicles with lower 

replacement ages. Fleets with an older average vehicle ages tend to purchase older 

used vehicles. 

Data reported in the ARB fleet survey was used regarding the year each vehicle was 

purchased and the year each vehicle would have been replaced, as shown in Table 

XIII-3. The cost model assigns a replacement vehicle age based on the average age of 

the individual fleet. 
-177- 

Table XIII-3: Statewide Weighted Average Vehicle Replacement Age 

Fleet Average Age Replacement 

Vehicle Age

0 to 3 0

>3 to 6 0

>7 to 10 1

>11 to 13 2

>14 to 16 5

>17 to 20 8

>20 10

As the average age of a fleet increases, the average replacement vehicle age 

increases. For example, if an individual company fleet has an average age of 8 years, 

then the cost model would select a 1 year old vehicle as the normal replacement for the 

vehicles in that individual company’s fleet. This, on average, represents the practice of 

buying some new vehicles and some used vehicles. For a company with an average 

vehicle age of 15 years, the replacement vehicle age would be five years old. 

The data collected by staff indicates that certain vehicles are kept longer than others. 

To account for this, the model establishes the likelihood that a particular vehicle would 

be replaced based on the vehicle age characteristics and vehicle category reflected in 

the emissions inventory. For example, a fleet with interstate registered tractors and instate heavy-duty vehicles is more likely to replace their interstate tractors more 

frequently because interstate vehicles generally travel more miles and are newer than 

other types of vehicles. This likelihood is identified as the vehicle’s relative age. A 

vehicle’s relative age takes into account the useful life of the fleet category and 

sequences that vehicle for replacement based on the amount of useful life it has left. 

For example, a CA IRP vehicle that accumulates high annual miles may have a short 

life of 7 years while an in-state tractor that travels moderate miles each year may have a 

longer life of 14 years. A vehicle that is 7 years old would have a higher relative age if it 

is in a CA IRP fleet that would replace vehicles at 7 years of age, than if it was in an instate tractor fleet that would not be replaced until 14 years of age. For each calendar 

year, vehicles in an individual company’s fleet are sequenced for replacement based on 

the vehicle’s “relative age”. The relative age is computed by taking the ratio of the age 

of the vehicle compared to the half-life for the vehicle category most representative from 

the statewide emissions inventory. 

The cost model evaluates one company at a time and each year replaces vehicles at 

the normal historical rate of vehicle replacement as indicated from the fleet survey data. 

The cost model continues this process from 2009 to 2030. Then, as described below, 

the model evaluates the actions taken to comply with the proposed regulation, using the 

same normal replacement rate and replacement vehicle age. 
-178- 

b) Modeling Compliance with the Proposed Regulation

As shown in Figure XIII-3, for each year, the cost model determines if the normal 

actions taken by the fleet would comply with the proposed regulation. If not, the cost 

model will first replace one vehicle at a time until the NOx criteria are met, and then will 

apply PM exhaust retrofits until the PM criteria are met. Staff programmed the model to 

replace the vehicle with the oldest relative age first, while vehicles with the newest 

relative age would be the first to receive verified DECS. This reflects the likelihood that 

fleet owners would install verified DECS on vehicles they intend to keep longer and 

would replace the vehicles that are closest to the end of their useful life. 

The entire procedure is then repeated for each year from 2009 to 2030 for each fleet. 

Due to accelerated replacement from the requirements of the proposed regulation, an 

individual company fleet may be newer than normal and no actions may be needed for 

a number of years. After 2023, the model steps through each year using each 

company’s normal fleet average replacement rate and average vehicle replacement 

age. The cost associated with the “regulation run” is compared with the “baseline run” 

cost to determine any increased cost due to the proposed regulation. This is needed to 

ensure that the baseline costs and costs with the regulation are compared for actions 

taken over the same period. This is also important in evaluating the vehicle age 

distribution and resulting impact on emissions in the years after the regulation period. 

The replacement sequence is not optimized to reduce costs, and vehicles are not 

purchased older than normal to lower the estimated cost of compliance. In actuality, 

many fleets will be required to purchase newer than normal vehicles between 2012 and 

2023 in order to meet the proposed regulatory requirements. Staff also modeled that 

fleets would purchase 2007 model year or newer vehicles through calendar year 2013 

and then starting in 2014 would not buy vehicles older than one with a 2010 model year. 

This assumption only changed the vehicle purchase age if the fleet being modeled 

would normally buy older vehicles in the given year. This conservatively reflects that 

fleet owners would buy newer than normal when a vehicle needed to be replaced even 

before the regulation would require it. Also, most fleet owners indicated they would 

minimize the purchase of aftermarket verified DECS and would rather purchase 

vehicles with OEM equipped filters. 
-179- 

Figure XIII-3: Annual Compliance Flowchart 

Determine normal 

vehicle replacements for 

next compliance date

W ill fleet meet BACT 

requirements?

Yes

 No

Will fleet meet NOx fleet 

average target?

Yes Will fleet meet PM 

fleet average target? Yes

 No No

Will minimum 2010 MY 

requirement be met?

Yes

W ill minimum PM 

retrofit requirement 

be met?

Yes

 No No

Modfiy replacement with 

a newer purchase or 

replace another vehicle

Install another PM 

retrofit

Done for 

Year

4. Model Results 

The costs for each fleet are then determined by comparing the modeled costs for 

normal vehicle replacement with that required under the proposed regulation. The 

increased cost is then divided by the number of vehicles to determine the average 

increased cost per vehicle. This information is then input into the statewide analysis 

where the increased per vehicle costs for each individual company are grouped by fleet 

age and fleet size. These average increased costs reflect that companies with newer 

fleets will have little or no increased costs, while companies with older fleets will have 

more substantial increased costs due to the proposed regulation. As shown in Figure 

XIII-4, Figure XIII-5 and Figure XIII-6, the average increased cost per vehicle associated 

with the proposed regulation varies by the average age of the fleet. 
-180- 

Figure XIII-4: Average Increased Cost for In-state Heavy-Heavy Duty 

Vehicles in Fleets with 4 or more Vehicles (excluding special provisions) 

$0

$10

$20

$30

$40

$50

$60

$70

$80

0 5 10 15 20 25

Average Fleet Age

(Years)

Average Increased Cost (Thousands $/Vehicle)
-181- 

Figure XIII-5: Average Increased Cost for In-state Medium-Heavy Duty 

Vehicles in Fleets with 4 or more Vehicles (excluding special provisions) 

$0

$10

$20

$30

$40

$50

$60

$70

$80

0 5 10 15 20 25

Average Fleet Age

(Years)

Average Increased Cost (Thousands $/Vehicle)

Figure XIII-6: Average Increased Cost for In-state Heavy-Heavy Duty Low 

Use NOx Exempt Vehicles (<7500 Miles) 

$0

$5

$10

$15

$20

$25

$30

0 5 10 15 20 25

Average Fleet Age

(Years)

Average Increased Cost (Thousands $/Vehicle)
-182- 

5. Scaling to Statewide Results 

The following table shows sample results from staff’s modeling of heavy heavy-duty 

vehicles that would not qualify for any of the proposed special provisions of the 

regulation. Registration data from the DMV provides the weighting percentages (based 

on vehicle age) that are applied to the total statewide vehicle population to get the 

number of vehicles in each fleet age group. The DMV weighting percentages in the 

table below do not match the percentages in Table XIII-5, as the vehicle population for 

Table XIII-4 excludes small fleets (less than 4 vehicles). 

Table XIII-4: In-state Heavy-Heavy Duty Vehicles by Fleet Age for Fleets with more 

than 3 vehicles (excluding fleets qualifying for special provisions) 

Fleet Age 

Number of 

Vehicles 

Percentage 

of Vehicle 

Population 

Average Increased 

Cost $/Vehicle 

(Per Model Output) 

Statewide Cost 

(millions of dollar) 

0 to 3 5,772 12.3% $0 $ 0 

>3 to 6 7,933 17.0% $7,688 $61 

>6 to 10 13,567 29.0% $13,981 $190 

>10 to 13 8,765 18.8% $20,274 $178 

>13 to 16 6,126 13.1% $25,668 $157 

>16 to 20 3,003 6.4% $31,961 $96 

>20 1,372 2.9% $40,052 $55 

Unknown 209 0.4% $15,756 $3 

TOTALS 46,750 100.0% $740 

Overall Average Increased $/Vehicle $15,827 

The statewide cost estimate for these vehicles can then be estimated by multiplying the 

number of these vehicles in the state by the increased cost per vehicle ($/vehicle in 

Table XIII-4) for each age group, and then summing the statewide cost (statewide cost 

in Table XIII-4) for each fleet age. In this example, the highest increased costs due to 

the regulation are found in “the over 20 years” (>20) fleet age category, with an average 

cost per vehicle of $40,052. The least cost impact due to the proposed regulation is 

found in the 0 to 3 fleet age category with no average increased costs. Medium heavyduty vehicles and vehicles qualifying for the special provisions, including low use 

vehicles, would have separate population counts and lower costs. 

The cost model output provides the average increased costs per vehicle by fleet age 

and fleet size for individual company fleets (see Appendix J for more information). For 

determining the statewide costs, staff matched vehicle types from real fleets who 

responded to the ARB survey to the emission inventory. Staff used DMV and IRP data 

to determine the distribution of medium duty vehicles, heavy duty vehicles, fleet size, 

and fleet age distributions. The vehicle population counts were derived from statewide 

emissions inventory database and include the following population categories: 
-183- 

• Intrastate 

o Heavy Heavy-Duty Vehicles (HHD) – Tractors 

o Heavy Heavy-Duty Vehicles – Non Tractors 

o Medium Heavy-Duty (MHD) Vehicles 

o Ag vehicles 

• Interstate 

o California International Registration Plan (CA IRP) Vehicles 

o Out-of-state neighboring vehicles (AZ, BC, ID, NV, OR, WA) 

o Out-of-state non-neighboring vehicles 

In addition to the statewide vehicle population groups, there are some additional subgroup vehicle counts needed because the regulatory requirements differ, such as for: 

• Low Mileage (<7500 for HHD & <5000 for MHD) Vehicles 

• Small Fleets (1-3 Vehicles) 

• Exempted Vehicles 

The characteristics of the fleet and vehicle information were used to match each vehicle 

to the emissions inventory categories. For example, a company may have some 

vehicles that are registered in the CA IRP, and also some that are medium and heavy 

heavy-duty vehicles that are registered instate. Based on DMV instate and CA IRP 

data, weighting percentages were developed by fleet age and size group to apply to the 

statewide emissions inventory populations to get the vehicle counts by fleet age and 

size groups. The statewide cost can be calculated for each fleet age group by 

multiplying the increased average cost per vehicle by the population vehicle counts. 

The number of vehicles by average fleet age used in staff’s analysis is shown in Table 

XIII-5. 

Table XIII-5: Vehicles by Fleet Average Age 

Vehicle Counts by Fleet Average Age 

Fleet Age 

In-state* 

pop. HHD 

In-state* 

pop. MHD 

CA IRP* 

pop. HHD 

Neighboring* 

pop. HHD 

Non-Neighboring 

IRP** pop. HHD 

0 to 3 12,263 41,864 9,244 6,394 327,572 

>3 to 6 18,693 42,183 19,368 13,396 31,636 

>6 to 10 38,245 57,594 20,028 13,853 38,844 

>10 to 13 27,054 26,049 4,182 2,892 2,002 

>13 to 16 18,044 19,137 935 647 400 

>16 to 20 13,455 13,593 660 457 - 

>20 10,224 9,625 550 381 - 

Unknown 763 447 55 38 - 

Totals 138,741 210,492 55,022 38,057 400,455 

Sources: *DMV 2006 age distribution 

 **IRP 2006 age distribution based on data from 12 states 

In general, newer fleets that normally replace their vehicles in a short period would incur 

little to no increased costs to comply with the proposed regulation, while older fleets that 

buy older vehicles and keep them longer would incur higher increased costs to comply. 
-184- 

Finally, as shown in Table XIII-6 below, the estimated statewide capital costs for vehicle 

replacements is $2.3 billion for in-state vehicles and $700 million for out-of-state 

vehicles. Similarly, the estimated statewide capital costs for installation of verified 

DECS are $1.4 billion for in-state vehicles and $200 million for out-of-state vehicles. 

The total regulatory capital costs of the proposed regulation are $4.6 billion. 

Table XIII-6: Summary of Average Increased Capital Costs 

Capital Costs Only (billions of dollars) 

Vehicle 

Replacements Verified DECS Totals 

In-state 2.3 1.4 3.7 

Out-of-state 0.7 0.2 0.9 

Totals 3.0 1.6 4.6 

Additional information on the anticipated number of retrofit needed for compliance with 

the proposed regulations is provided in the next section of this chapter. 

6. Annual Costs 

In addition to capital costs of the proposed regulation, various annual operational and 

maintenance costs will also be incurred. In determining the total regulatory costs of 

staff’s proposal, these annual costs are added to the total statewide capital cost 

estimates. Operational and maintenance costs associated with verified DECS include 

annual filter cleaning expenses, fuel economy losses and costs associated with 

regeneration of active systems. Other costs or savings include fuel economy 

improvements with replacement of older vehicles with newer vehicles and urea costs for 

SCR. At this time, staff has not included anticipated cost savings associated with lower 

maintenance and less down time with newer vehicles compared to older vehicles. 

The operating and maintenance costs associated with the use of verified DECS are 

determined using the anticipated population of vehicles equipped with aftermarket PM 

controls, as well as the population of 2007 and newer engines. The number of PM 

controls in each calendar year was estimated by extrapolating the results of the capital 

cost model to the affected vehicle population. 

Operating and maintenance costs attributable to the proposed regulation were broken 

into four main categories: regeneration cost for active DPFs, changes in fuel economy, 

urea usage, and annual maintenance. Regeneration costs for active filters are incurred 

for electricity or fuel usage for a vehicle to regenerate the filters on a regular basis. 

Annual maintenance costs for vehicles with PM control devices are for the cleaning 

servicing of the filters by external parties. Engines manufactured after 2009 with SCR 

would also have annual costs associated with the use of urea. Also, there is likely to be 

a fuel economy improvement and associated cost savings through the use of 2004-

2006 MY engines utilizing EGR. 
-185- 

a) Annual DPF Costs 

When calculating the statewide costs, additional costs due to DPFs were also 

incorporated. These include the costs associated with regeneration of active PM 

exhaust retrofits on pre-1994 vehicles, the expected number regenerations per week, 

and the cost of electricity or fuel used per regeneration. In addition, PM exhaust 

retrofits are expected to decrease fuel economy by 2 percent. The total statewide fuel 

costs associated with DPFs are estimated by the average fuel economy and annual 

miles traveled by vehicles with aftermarket PM controls. Finally, annual maintenance 

includes an estimated average filter cleaning cost of $400. 

i. Estimated Number of Retrofits 

The estimated incremental number of DPFs that will need to be installed because of the 

proposed regulation in the statewide fleet is shown in Figure XIII-7. The filter retrofits 

begin in 2010 and are completed by the end of 2013. Also displayed are the estimated 

number of increased vehicles with OEM installed DPFs as a result of the proposed 

regulation. It is expected that after 2021, the incremental number of vehicles having 

DPFs because of the accelerated vehicle replacement required with the proposed 

regulation will slowly decrease as these vehicles are replaced and the statewide fleet 

goes back to normal vehicle age distribution. 
-186- 

Figure XIII-7: Number of DPFs in Statewide Fleet Resulting from Proposed 

Regulation 

0

50,000

100,000

150,000

200,000

250,000

201020112012201320142015201620172018201920202021202220232024202520262027202820292030

Calendar Year

PM Filter Counts

Vehicle Retrofit

Accelerated Vehicle

Replacement

ii. Regeneration Costs 

Staff expects the majority of vehicles needing to be retrofit will use passive DPFs. 

However, because of temperature requirements with passive DPFs, active fuel-based 

systems, will also be needed. Staff believes that active fuel-based systems may be 

preferable for fleets so that they may avoid the need to plug in electrically regenerated 

DPFs because many vehicles (dump trucks, being a good example) may not have on 

the job access to electricity nor the extended time for a full electricity-based 

regeneration cycle, which can take as long as 8 hours. Electricity-based regeneration 

should remain commonplace in day-use applications where the vehicle returns to the 

same facility each night, such as shuttle bus and local delivery fleets. 

Given the similarity in regeneration costs between the two technologies, staff estimated 

these costs by using fuel-based DPFs exclusively in the analysis. To estimate the 

number of active DPFs expected to be installed as a result of the proposed regulation, 

the retrofit population was scaled by the weighted in-state percentage of pre-1994 

medium heavy-duty and heavy heavy-duty vehicles, which is 15 percent of the 

population. The staff estimates is based on two regenerations per week and 0.2 gallons 

of diesel fuel consumed per regeneration, and one half hour of employee time to plug-in 

or wait for the system to regenerate. A vast majority of the cost is attributed to the down 

time and the total cost is insensitive to fuel price. The total cost to the statewide fleet 

was estimated to be $181.7 million at a diesel fuel price of $3.69 per gallon. At $4.00 

per gallon of diesel, the cost would increase to $182.3 million; and at $5.00 per gallon, 

this cost would further increase to $184.2 million.
-187- 

iii. Maintenance Costs 

Between 2010 through 2013, the proposed regulation would require the retrofit 

installation of DPFs on existing vehicles that do not already have them. After 2013, the 

incremental population of vehicles having retrofit filters will decrease because of the 

replacement of these vehicles with vehicles meeting the NOx and PM performance 

standards of the proposed regulation. The proposed regulation will also accelerate the 

replacement of vehicles to vehicles that have a DPF installed by OEM engine 

manufacturers. This will result in an increased number of vehicles in the statewide fleet 

with their DPFs relative to what would occur without the proposed regulation. The total 

estimated number of retrofits in the statewide fleet, by year, was previously shown 

Figure XIII-7. 

Staff has estimated that each retrofit will result in maintenance costs of about $250 per 

year for pre-installed OEM Devices and about $400 per year for post-installed PM 

retrofits. Using their estimate, the total statewide costs due to retrofit maintenance was 

calculated using Equation XIII-2. 

Equation XIII-2: Total Maintenance Costs = Σ (maintenance cost/year per 

vehicle x # of vehicles in the state retrofitted) 

The total increased in maintenance costs for the statewide fleet from 2010 to 2030 is 

estimated at $430 million (in 2008 equivalent dollars), as shown in Table XIII-7 below. 

Table XIII-7: Cumulative Increased Retrofit Maintenance Costs ($2008) 

Per Filter Costs 

Cumulative Costs 

(millions) 

OEM equipped DPFs $ 190 

Aftermarket DPFs $ 240 

Total $ 430 

iv. Changes in Fuel Economy 

Statewide fleets with vehicles subject to the proposed regulation use over 3 billion 

gallons of diesel fuel per year (for their California miles traveled) at an average cost of 

approximately $4.0021 per gallon (California Energy Commission, September 2008). 

The use of retrofit DPFs can result in a small loss of fuel efficiency (about 2 percent), 

resulting in increased fuel costs. 

As part of the ARB fleet survey, fleets reported vehicle fuel usage and miles traveled. 

Data used in the development of the statewide emission inventory (including vehicle 

miles traveled) was then used to compute the costs associated with fuel economy 

penalty DPFs. Figure XIII-8 shows the estimated fuel economy of medium and heavy 

heavy-duty diesel vehicles without DPFs. The fuel usage for statewide vehicles was 

calculated both with and without the proposed regulation using the estimated fuel 

 

21 Price of California No 2 Diesel in September 2008 (http://energyalmanac.ca.gov/gasoline/). 
-188- 

economy shown in Figure XIII-8. Overall, replacing older vehicles with newer vehicles 

results in a net savings from increased fuel efficiencies. However, most of the fuel 

efficiency savings are offset by a two percent fuel penalty for vehicles with PM filter 

retrofits. 

Figure XIII-8: Estimated Fuel Economy of Diesel Vehicles by Vehicle Model 

Year 

The total statewide fuel economy penalty costs between 2010 and 2030 due from DPF 

retrofits is estimated to be approximately $113 million ($2008). The total statewide cost 

benefit in 2010 to 2030 due to decreased fuel consumption from the accelerated 

introduction of more fuel efficient vehicles is about $126 million (2008 dollars). Thus, 

there is a net reduction in costs of approximately $13 million at a fuel price of $4.00 per 

gallon. At a price of $3.69 per gallon, the net reduction in costs would be about $12 

million and at a price of $5.00 per gallon the net reduction in costs would be about $17 

million. 

b) Selective Catalytic Reduction Costs 

The proposed regulation will also accelerate the replacement of existing vehicles to 

newer vehicles that utilize SCR technology. The result is an increased number of 

vehicles in the statewide fleet that have SCR relative to what would occur without the 

proposed regulation. SCR technology utilizes urea to reduce NOx emissions, so an 

additional cost will be realized. It is expected that after 2023, the increased number of 

vehicles having SCR because of the accelerated vehicle replacement requirement will 

slowly decrease as the statewide fleet returns to normal vehicle replacement cycles. 

Projecting in 2008 equivalent dollars, and considering urea costs of $4.00 per gallon 

and that urea consumption in SCR is expected to be about 3 percent of the diesel fuel 

used, the estimated cost is approximately $240 million. 

0

2

4

6

8

10

1980

1983

1986

1989

19921995

1998

2001

20042007

2010

201320162019

Model Year

Miles per Gallon

HHDDT, MPG

MHDDT, MPG
-189- 

C. Reporting Cost 

For small fleets, staff estimates that the initial reporting will cost between $0 and $100 

(for up to 2 hours needed to compile fleet data). This assumes a cost of $50 per hour 

for either work time lost, or to hire a consultant. For larger fleets, the cost was estimated 

to vary between $200 and $400 (assuming an average of 4 to 8 hours to compile larger 

fleet data). 

For estimating the total statewide costs, the number of fleets present in the state was 

estimated using 2006 DMV and CA IRP data with the number of registered vehicles 

grouped by fleet size bins. The number of fleets was calculated using Equation XIII-3. 

Equation XIII-3: Fleets in State = Σ [Registered Vehicles / Fleet Size] 

Using 2006 DMV data for in-state heavy heavy-duty, medium heavy-duty and CA IRP 

vehicle populations, staff estimates there are approximately 171,500 fleets in California 

subject to the proposed regulation. Approximately 156,000 of these fleets are small 

fleets (having three or fewer vehicles) and approximately 15,500 are larger fleets. To 

estimate the reporting costs, staff used Equation XIII-4. 

Equation XIII-4: Fleet initial reporting costs = # of fleets x 75% x average initial 

reporting costs 

In $2008 dollars, the anticipated statewide cost for fleets to comply with initial reporting 

requirements in 2010 is shown below in Table XIII-8. 

Table XIII-8: Initial Reporting Costs (2010) 

Fleet Type Cost ($2008) 

(millions) 

Small fleet $11 

Larger fleet $ 5 

Total cost for initial reporting $16 

Staff estimated the on-going annual reporting costs for small fleets to be approximately 

$50 per fleet per year, assuming an average of one hour is needed to update the fleet 

information in the ARB reporting system. For a larger fleet, this cost is estimated to be 

$200 per fleet per year, assuming that, on average, 4 hours is needed to update the 

fleet information in the ARB reporting system. The 4 hours for larger fleets is based on 

a weighted average using 1.5 hours for fleets with 4 to 5 vehicles, 2 hours for fleets with 

6 to 10 vehicles, 4 hours for fleets with 11 to 20 vehicles and 20 hours for fleets with 

over 20 vehicles. The total annual cost for small fleet reporting will be 75 percent of the 

estimated number of fleets multiplied by $50, or $5 million per year. For larger fleets, 

the cost per year will be 75 percent of the number of fleets multiplied by $200, or $2 

million per year. 
-190- 

The reporting costs over the life of the regulation were calculated using Equation XIII-5, 

assuming that for all fleets reporting ends in 2022. 

Equation XIII-5: Total annual reporting cost = Σ (Annual reporting cost for every 

year of reporting) 

The total annual reporting cost over the life of the regulation is shown in Table XIII-9. 

Table XIII-9: Total Annual Reporting Costs 

Fleet Type Cost ($2008) 

(millions) 

Small fleet $42 

Larger fleet $19 

Total cost for annual reporting $61 

The total reporting costs for the proposed regulation are the sum of initial and annual 

reporting costs (in 2008 dollars). This is shown below in Table XIII-10. 

Table XIII-10: Total Reporting Costs 

Fleet Type Cost ($2008) 

(millions) 

Small fleet $53 

Larger fleet $24 

Total cost for reporting $77 

D. Total Statewide Costs 

The total increased cost due to the proposed regulation (in 2008 dollars) for fleets 

operating in California is estimated to be $5.5 billion, as shown in Table XIII-11. About 

$4.5 billion of the cost would be incurred by fleets with vehicles based in California and 

$1.0 billion would be incurred by out-of-state fleets. A detailed explanation of the 

methodology and input costs used to make the estimates are discussed in Appendix J. 
-191- 

Table XIII-11: Summary of Average Increased by Statewide Fleet Groups 

Fleet/Population 

Type 

Capital 

Cost 

(millions) 

Annual 

Costs 

(millions) 

Total Cost 

(millions) 

# 

Vehicles

In-state MHD* $1,194 $450 $1,643 219,392 

In-state HHD $1,559 $302 $1,861 147,074 

Interstate CA IRP $498 $118 $616 57,399 

Interstate 

Neighboring/NonNeighboring $858 $81 $939 490,359 

Motorcoach & 

School Buses $348 $54 $402 26,443 

Totals $4,457 $1,005 $5,461 940,667 

*Includes about 9,000 CA IRP and out-of-state vehicles. 

E. Cost Effectiveness of the Proposed Regulation 

Cost-effectiveness is expressed as control costs in dollars per unit of pollutant 

emissions reduced in pounds ($/lb). The cost-effectiveness for the proposed regulation 

is determined by dividing the total capital costs plus the annual costs by the total 

pounds of diesel PM and NOx reduced during the years 2010 to 2030. The expected 

cost effectiveness of this regulation is $1.76/lb for NOx and $46/lb for PM. All costs are 

in $2008. 

In considering the cost effectiveness of the regulation relative to premature mortality 

avoided, a PM cost effectiveness of $46/lb of PM is about 5.5 times lower than the U.S. 

EPA’s benchmark for value of avoided death (which equates to about $248/lb). 

Therefore, proposed regulation is a cost-effective mechanism to reduce premature 

deaths that would otherwise be caused by diesel PM emissions without this regulation 

relative to that benchmark. 

Table XIII-12 below compares the estimated cost-effectiveness of the proposed 

regulation to the estimated cost-effectiveness of other recently adopted diesel 

regulations. For comparison purposes, all cost-effectiveness estimates shown in Table 

XIII-12 attribute part of the total regulation cost to PM reductions and part to NOx 

reductions. Regulations are ranked from lowest $/lb PM cost to highest. 
-192- 

Table XIII-12: Comparison of the Average Cost-Effectiveness of the 

Proposed Regulation to Average Cost Effectiveness of Recently Adopted Air 

Toxic Control Measures 

Regulation $2008 /lb NOx 

Cost-effectiveness

$2008 /lb PM Costeffectiveness Source of 

Estimate 

Stationary 

Compression Ignition 

Engine ATCM 

0.92/lb HC+NOx $7.70/lb PM (ARB, 2003b) 

Portable Engine ATCM <$2/lb NOx $8-10/lb PM (ARB, 2004) 

Cargo Handling ATCM $1/lb NOx $21/lb diesel PM (ARB, 2005a) 

Solid Waste Collection 

Vehicle ATCM 1.79/lb HC+NOx $32/lb PM (ARB, 2003a) 

In-Use Off-Road 

Diesel Vehicle Rule $2.1 - 2.5/lb NOx $37 - 43/lb PM (ARB, 2007) 

Proposed Regulation $1.4 – 1.9/lb NOx $42 – 48/lb PM See Chapter XIII 

Public Fleets Rule $10.9/lb HC+NOx $160/lb PM (ARB, 2005b) 

F. Cost Model Methodology for Industry Sectors 

1. Overview 

Staff used fleet vehicle data reported in the fleet survey to proportion the in-state vehicle 

population by weight class and fleet age group for a number of industry sectors. These 

included transportation, construction, agriculture, retail and wholesale, and other 

services. U.S. Census Bureau 2002 Vehicle Inventory and Use Survey (National 2002 

VIUS) truck data was used to allocate the total number of in-state vehicles to each 

industry group by weight class, as discussed below. Proportions of vehicles by weight 

class and fleet age groups in the National 2002 VIUS truck data were reviewed for 

context; however the cost model relied on the proportions derived from the more current 

California fleet survey to be consistent with the method used for the statewide fleet 

groupings. 

The increased costs per vehicle by weight class were based on prior analyses for 

statewide fleet groupings. The percentage of vehicles in each fleet age group was 

multiplied by the allocated number of in-state vehicles to get the estimated number of 

vehicles for each age group by industry sector. These counts by age group were then 

multiplied by the increased cost per vehicle and summed across all age groups to 

estimate the statewide capital costs for each industry sector. 

The costs for motor coach bus lines, school districts, and utilities were calculated 

separately using emissions inventory vehicle count data and modeling the specific rule 

provisions. ARB staff computed the increased capital costs over the period from 2010-

2030 and also calculated the maximum year costs for each industry. 

More detail on the analysis of the economic impacts on business sectors can be found 

in Appendix J. 
-193- 

2. Vehicles by Business Type 

The impact of the proposed regulation on each business sector will depend on the 

number and types of vehicles that are impacted and the fleet ages for each business 

sector. Figure XIII-9 summarizes the National 2002 VIUS data by the percent of the 

vehicle population to business type for heavy heavy-duty and medium heavy-duty diesel 

vehicles. 

Figure XIII-9: Percentage of Vehicle Population by Business Sector from 

National 2002 VIUS Data 

 Heavy Duty Vehicles Medium-Duty Vehicles

Vehicle 

Leasing or 

Rental

5%

Manufacturing 

& Mining

8%

Agriculture, 

Forestry, 

Fishing, or 

Hunting

16%

Other 

Services

12%

Construction

22%

Retail & 

Wholesale 

Trade

10%

For-Hire 

Transportation 

or 

Warehousing

27%

Vehicle 

Leasing or 

Rental

9%

For-Hire 

Transportation 

or 

Warehousing

19%

Retail & 

Wholesale 

Trade

19%

Construction

18%

Other Services

19%

Agriculture, 

Forestry, 

Fishing, or 

Hunting

10%

Manufacturing 

& Mining

6%

The total in-state heavy heavy-duty and medium heavy-duty inventory vehicle 

population’s were multiplied by the appropriate National 2002 VIUS vehicle percentages 

for each industry sector type to get the total number of vehicles allocated to each 

industry by weight class. The in-state annual operating and reporting costs were 

apportioned to each industry sector based on the annual miles travelled for each 

industry sector, as per the 2002 VIUS national data. The increased costs by sector are 

summarized below in Table XIII-13. 
-194- 

Table XIII-13: Increased Costs by Business Sector 

Business Sector 

Increased 

Capital Costs 

(in millions of 

$2008) 

Annual Costs 

(in millions of 

$2008) 

Total Increased 

Costs (in 

millions of 

$2008) 

Accommodation or Food Services $ 83.5 $ 14.7 $ 98.2 

Agriculture, Forestry, Fishing, or Hunting $ 197.7 $ 68.0 $ 265.7 

Arts, Entertainment or Recreation 

Services $ 14.0 $ 0.9 $ 14.9 

Construction $ 960.1 $ 100.4 $1,060.5 

For-Hire Transportation or Warehousing $1,359.0 $ 486.2 $1,845.2 

Manufacturing $ 124.9 $ 43.3 $ 168.2 

Mining $ 117.1 $ 20.1 $ 137.2 

Other Services $ 84.6 $ 48.5 $ 133.1 

Retail & Wholesale Trade $ 401.3 $ 105.5 $ 506.8 

Utilities $ 3.9 $ 10.2 $ 14.1 

Vehicle Leasing or Rental $ 207.9 $ 71.1 $ 279.0 

TOTALS $3,554.0 $ 968.9 $4,522.9 

This industry sector cost analysis computes the increased capital costs for vehicles 

registered in-state and does not include costs to out-of-state operators. However, staff 

expects the majority of costs to out-of-state fleets to be borne by the transportation and 

warehousing sector. 

G. Sensitivities in Estimating Statewide Costs 

The total economic costs imposed by this regulation on the statewide fleet would 

depend on the compliance path chosen by each business and the compliance options 

available to them. 

1. Retrofit 

a) Retrofit SCR 

Staff examined the possibility of requiring verified NOx DECS in addition to verified PM 

DECS, however high level verified NOx DECS are not yet commercially available and 

are expected to have substantial cost. As such, while the proposed regulation 

maintains flexibility to meet emission targets with verified NOx DECS should they 

become available, it does not require them. 

To evaluate how the use of verified NOx DECS could impact staff’s cost estimate, the 

cost model was run with 119 sample fleets containing 1,440 vehicles, to examine the 

difference of Level 3 DECS versus installing SCRs. The vehicles modeled use model 

year 1994 and newer, and SCR retrofit was estimated to cost $25,000 and provides a 

70 percent NOx reduction. As summarized in Table XIII-14, the overall average cost 

was reduced by almost 17 percent across all of the sample fleets. The additional NOx 

emission reductions realized through the use of the SCR retrofit decreased the number 
-195- 

of replacements needed. Fleets with newer vehicles would have no cost differences 

because they already would be replacing vehicles faster than the regulation would 

require and would not need to install SCR systems. Fleets with the oldest vehicles 

would not see any reduction in costs because they would likely travel fewer miles and 

would have several vehicles exempt from the NOx criteria or because staff modeled that 

older fleets would purchase older used vehicles and the SCR system may not cost less 

than replacing the vehicle and selling the retired vehicle. 

Table XIII-14: Cost Sensitivity Analysis for Use of NOx Retrofits 

Average Age of 

Sample Fleet Change in Costs 

Less than 8 years No Change 

8 to 18 years Decreased 

More than 18 years No Change 

All Fleets 17% Decrease 

b) Increased PM Retrofit Costs 

The cost model assigned passive exhaust retrofit costs of $11,000 for medium heavyduty and $12,000 for heavy heavy-duty vehicles, and a cost of $15,000 for all active 

retrofits. Staff examined the impact an increased retrofit cost of $5,000 for all size 

vehicles would have by modeling 119 sample fleets with 1,440 vehicles. As 

summarized in Table XIII-15, the overall average increased cost was 20 percent across 

all of the sample fleets. Newer fleets would have no significant costs because they 

would have a higher proportion of vehicles with OEM equipped DPFs and would not 

need to install many aftermarket PM retrofits. In contrast, fleets with an older average 

age would have more vehicles without OEM equipped filters and would need to install a 

higher number of PM retrofits; therefore, the costs would increase for these fleets. 

Table XIII-15: Cost Sensitivity Analysis for Increased Retrofit Costs 

Fleet 

Average Age Change in Costs 

>9 Years Increased 

<10 Years No Change 

All Fleets 20% Increase 

2. Optimization Strategies 

Individual fleets will be able to assess the options that are available to them in meeting 

the proposed regulation and can examine strategies for optimized results. For example, 

mixed medium and heavy heavy-duty vehicle fleets could sequence their replacements 

such that the medium heavy-duty vehicles with lower costs would be replaced first and 

delay heavy heavy-duty vehicle replacements so they would occur closer to the normal 

replacement cycle. Fleets with older vehicles that would require installation of higher 

cost active filters might find the costs to purchase used vehicles with pre-installed filters 

to be less costly than to install the active filters. In addition, these used vehicles can 
-196- 

remain in the fleet much longer than the older vehicles with the post-installed filters and 

the replacement costs for a model year 2010 vehicle could be delayed. Overall, staff 

believes that as fleets optimize their compliance activities, the overall estimated costs of 

the proposed regulation are likely conservative. 

H. References 

ARB, 2003a. California Air Resources Board. Staff Report: Initial Statement of 

Reasons, Supplemental Report, for Proposed Diesel Particulate Matter Control 

Measure for On-Road Heavy-Duty Residential and Commercial Solid Waste Collection 

Vehicles. August 8, 2003. 

http://www.arb.ca.gov/regact/dieselswcv/isor3.pdf 

ARB, 2003b. Air Resources Board. Staff Report: Initial statement of Reasons for 

Proposed Rulemaking Airborne Toxic Control Measure for Stationary Compression 

Ignition Engines. September 2003 

http://www.arb.ca.gov/regact/statde/isor.pdf

ARB, 2004. Air Resources Board. Staff Report: Initial Statement of Reasons for 

Proposed Rulemaking Airborne Toxic Control Measure for Diesel-Fueled Portable 

Engine. January 2004 

http://www.arb.ca.gov/regact/porteng/isor.pdf

ARB, 2005a. California Air Resources Board. Staff Report: Initial Statement of 

Reasons for Proposed Rulemaking, Adoption of the Proposed Regulation for Mobile 

Cargo Handling Equipment at Ports and Intermodal Rail Yards. October 2005. 

http://www.arb.ca.gov/regact/cargo2005/isor.pdf

ARB, 2005b California Air Resources Board: Staff Report: Initial Statement of 

Reasons for Proposed Diesel Particulate Matter Control Measure for On-Road HeavyDuty Diesel-Fueled Vehicles Owned or Operated by Public Agencies and Utilities. 

October 2005 

http://www.arb.ca.gov/regact/dpmcm05/isor.pdf

ARB, 2007. California Air Resources Board. Technical Support Document: Proposed 

Regulation for In-Use Off-Road Diesel Vehicles. April 2007 

http://www.arb.ca.gov/regact/2007/ordiesl07/TSD.pdf

National 2002 VIUS. U.S. Census Bureau 2002 Economic Census: Vehicle Inventory 

and Use Survey. EC2TV-US. Issued December 2004 
-197- 

XIV. ECONOMIC IMPACTS

As presented in the Chapter XIII, the total statewide costs of the proposed regulation 

are estimated to be about $5.5 billion. About $4.5 billion is attributable to in-state 

vehicles and about $1 billion is attributable to out-of-state vehicles. In this chapter, a 

discussion of the economic impacts of these costs on the economy of the state, and on 

affected business sectors, is discussed. 

A. Background 

1. Estimating Economic Impacts 

Developing control cost estimates provides a means to estimate the direct expenditures 

that would be incurred by California businesses, governments, and individuals to meet 

the requirements in the proposed regulation. Depending on the significance of these 

costs, they could in turn bring about additional (indirect) changes in the California 

economy. Increased control costs for all on-road vehicles, for example, may result in 

higher prices to perform certain services. California firms may respond by cutting back 

production and decreasing employment. On other hand, the requirements in the 

proposed regulation may also increase demand for retrofitting, repowering, and new 

vehicles, thus inducing firms supplying those products and services to expand their 

production and increase their hiring of workers. 

This change in economics could in turn affect other industries both negatively and 

positively. The net effect on the California economy of these activities hinges on the 

extent to which products and services are obtained locally. Using a new version of the 

E-DRAM model (a macroeconomic model of the California economy), staff estimated 

the net effects of these activities on affected industries and the overall economy. The 

California industries affected most are those engaged in the use of heavy-duty vehicles, 

such as the transportation and warehousing industry. Also affected are industries that 

are engaged in installing retrofits, maintaining vehicles, or selling them. 

The economic model used for this analysis does not account for the significant health 

benefits to California businesses and citizens that this regulation would bring. Actions 

to improve air quality reduce illness and premature death, and increase natural 

resources and work force productivity thereby providing significant societal cost savings. 

This regulation is also likely to induce significant advancement of clean diesel engine 

technologies by California based companies. ARB staff estimates that the benefits to 

California of currently adopted air pollution control measures exceed their costs by 

about 10 to 1. That is, each dollar spent on clean air generates on average ten dollars 

in social benefits that improve the quality of life. 

2. Environmental-Dynamic Revenue Analysis Model (E-DRAM) 

The overall impact of all direct and indirect economic effects associated with the 

proposed regulation is estimated using a computable general equilibrium (CGE) model 

of the California economy. A CGE model simulates various economic relationships in a 

market economy where prices and production adjust in response to changes in behavior 
-198- 

resulting from regulatory changes. More specifically, it describes the relationships 

among producers, consumers, government, and the rest of the world. The CGE model 

used for this analysis is the latest updated version of the E-DRAM. E-DRAM was first 

developed as DRAM for the California Department of Finance22. The model can be 

used to measure the total impact of a change caused by a regulation in one industry on 

all other industries within California. The economic impact results are measured in 

terms of changes in the State output, personal income, and employment. 

The new model is based on a revised database called a social accounting matrix 

(SAM). The revisions to SAM include a calibration of the base year in the model to 

calendar year 2003 from fiscal year 1998-1999, an updating of energy data, and a more 

detailed sectoring of the California economy. The new E-DRAM divides the California 

economy into 174 distinct sectors, consisting of 108 industrial sectors, 2 factor sectors 

(labor and capital), 8 household sectors (classified by income level), 9 composite goods 

sectors, 1 investment sector, and 45 government sectors (7 federal, 27 State, and 11 

local), and 1 sector that represents the rest of the world. 

Data for the industrial sectors originated with the Bureau of Economic Analysis of the 

U.S. Department of Commerce, based on the Census of Business – a detailed survey of 

companies conducted in the U.S. every five years. The conversion of national data to 

updated California data is accomplished by Impact Analysis for Planning (IMPLAN), a 

program that primarily utilizes state-level employment data to scale national-level 

industrial data down to the size of a state. 

In much the same way as firms, households are also aggregated. California 

households were divided into categories based upon their taxable income. There are 

seven such categories in the model, each one corresponding to a California personal 

income tax marginal tax rate (0, 1, 2, 4, 6, 8, and 9.3 percent). Thus, the income for the 

“one-percent” household is calculated by adding up the income from all households in 

the one-percent bracket. 

Similarly, the expenditure of the one-percent household on agricultural goods is 

calculated by adding up all expenditure on agricultural goods for these households. The 

total expenditure on agricultural goods is found by adding the expenditure of all 

households together. 

B. Economic Impacts on the California Economy 

1. Direct Costs 

The proposed regulation imposes capital costs on a number of industries; the most 

costly year of the regulation was used for this analysis ($566 million in 2013). Estimates 

of the maximum annual costs for each affected industry are provided in Table XIV-1. As 

shown in the table, the transportation and warehousing sector has the highest increased 

 

22 For a complete description of DRAM, see Berck, Peter, E. Golan and B. Smith, “Dynamic Revenue 

Analysis for California, California Department of Finance, Summer 1996. 
-199- 

capital cost in 2013 at 51 percent of the total. The construction industry has the second 

highest increased capital cost in 2013 at almost 21 percent of the total. 

Table XIV-1: Estimates of Total Capital Costs of Proposed Regulation by Affected 

Industries in 2013 (Millions of 2008 Dollars) 

Industry Capital 

Costs Percentage 

Accommodation and Food Services $15.1 2.7 

Agriculture, Forestry, Fishing $41.4 7.3 

Arts, Entertainment or Recreation Services $2.0 0.3 

Construction $117.1 20.7 

Transportation and Warehousing $288.5 51.0 

Manufacturing $18.9 3.3 

Mining $17.7 3.1 

Other Services $9.4 1.7 

Wholesale and Retail Trade $55.7 9.8 

Total $565.8 100 

2. Overall Statewide Economic Impact 

Increased capital costs of the proposed regulation would affect the California economy 

through many complex interactions. E-DRAM was developed to simulate many of these 

complex interactions. Using the model, staff in consultation with U.C. Berkeley 

researchers conducted an assessment of the economic impacts of the proposed 

regulation on the California economy. 

Table XIV-2 summarizes the impact of the proposed regulation on the California 

economy in the year 2013, when the annual capital costs to the affected industries were 

the highest. Staff projects the capital costs of the proposed regulation would reduce 

California economic output by roughly $1.3 billion (0.04 percent) and California 

employment by approximately 4,600 to 13,600 jobs (less than 0.08 percent) in 2013. 

Personal income projections would also decline by roughly $500 to $600 million (-0.02 

percent) in 2013. 
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Table XIV-2: Impact on the California Economy of Proposed Regulation in the 

Year 2013 (Billions of 2006 Dollars) 

California Economy Without 

Regulation 

With 

Regulation 

Difference 

(Impact) 

Difference 

(Percent) 

Output 3,104 3,103 -1.3 -0.04 

Personal Income 1,800 1,799 -0.6 -0.02 to 0.02 

Employment 

(thousands) 17,630 17,620 to 17,630 0 to 10 -0.03 to -0.08 

3. Conclusion 

Total annual fleet capital costs associated with the proposed regulation are estimated to 

be approximately $566 million in 2013. Accounting for indirect costs, the proposed 

regulation is expected to reduce California economic output by about $1.3 billion, 

personal income by about $0.5 to $0.6 billion, and employment by as many as 13,600 

from their projected levels in 2013. In the context of the State’s economy ($3.1 trillions), 

the economic impact of the proposed regulation is minor and is not expected to impose 

a noticeable impact. Additional details on staff’s analysis can be found in Appendix J. 

C. Economic Impact on Individual Business Sectors 

Although there are considerable differences in types of vehicles and how they are used 

among various industry sectors, there are some commonalities. Heavy-duty engines 

are designed to operate up to 1,000,000 miles. In general, few companies will operate 

vehicles significantly beyond this point because the cost of repairs will often exceed the 

value of keeping the vehicle, and in most operations reduced vehicle reliability presents 

additional business risks and costs. As a vehicle ages it is more likely to be placed in 

local service or in an application where high reliability is less critical. As the vehicle 

nears the end of its useful life, it is often placed in a back-up service or in low use 

application. 

In this section, staff provides information on the economic impacts of a number of 

business sectors impacted by the proposed regulation. These include the: 

• Transportation sector, including various subsectors; 

• Agricultural sector; 

• Construction sector; 

• Manufacturing sector; 

• Retail and wholesale trade sector; 

• Schools, and; 

• Federal fleets. 

Within the discussion of each business sector, staff provides an overview, including a 

description of the typical make-up of fleets and their vehicle replacement practices. 

Staff also provides an assessment of the economic impact of the proposed regulation 
-201- 

on the sector, the cumulative costs of the proposed regulation and other ARB 

regulations, and the ability of fleets to pass through their compliance costs. As part of 

staff’s analysis a number of industry case studies were performed. A number of these 

are provided in this chapter, and the remainder are in Appendix J. 

1. Transportation Sector 

The Transportation and Warehousing sector includes air, pipeline, rail, water, truck, 

transit and ground passenger transportation. Truck transportation is the largest 

subgroup in this sector, including busses and motor coaches used in local 

transportation and tourism. The gross domestic product for this sector from the 2006 

California Statistical Abstract for 2004 was $35 billion. Within the sector, truck 

transportation, passenger transportation and other support activities represent about 

$24 billion of the total. 

For comparative purpose, staff also evaluated California specific transportation sector 

data from FleetSeek. FleetSeek is part of Fleet Owner Magazine, and provides data on 

the trucking industry for fleet operators. This data contained information for 21,487 

individual companies with a total of 259,000 vehicles in various sections and allocates 

number of vehicles and revenues by Standard Industrial Classification (SIC) code for 

hire carriers, private carriers and other companies with trucks. The data also identifies 

characteristics about the vehicle weight class and vehicle configuration important for 

understanding the cost impacts of the proposed regulation. For the trucking sector 

FleetSeek reports about $19 billion in gross revenue for 2006. However, because it is 

not a complete data set for all companies in California, the total figures should be 

considered a lower bound estimate. As such, staff believes the data from the 2006 

California statistical abstract for 2004 provides a more appropriate measure of the 

economic output of this sector. 

a) Industry characteristics of the Transportation Industry 

(1) Trucking Companies 

Trucking companies primarily utilizing heavy-duty, truck-tractor trailer combinations, that 

travel relatively high miles compared to other sectors, generally have newer vehicles. 

Within trucking there are a number of categories that characterize different vehicle 

usage patterns and business models. Interstate vehicles tend to travel the highest 

annual miles, and in-state truck-tractors tend to be purchased used and travel fewer 

miles. 

Many trucking companies specialize in certain freight types and compete with other 

companies having similar equipment. For example, companies may specialize in 

refrigerated freight, bulk materials, liquids, hazardous waste, dry goods or other items. 

Most of these transportation businesses will have several tractor-trailer combinations 

with similar design or function, maximizing their flexibility in moving various goods 

locally, throughout the state, and across the country. 
-202- 

Few trucking companies will operate Class 8 trucks significantly beyond 1,000,000 

miles. Long haul trucks that operate 100,000 to 200,000 miles per year are commonly 

purchased new and sold within 3 to 7 years. This maximizes the fleet reliability while 

the resale value of the vehicle remains relatively high. In the secondary market, these 

used vehicles are often purchased by fleets that may operate their vehicles regionally or 

locally and do fewer annual miles. After another 5 to 10 years the vehicle is often sold 

to a fleet that operates the vehicle for the remainder of its useful life. Fleets that operate 

their vehicles fewer miles per year generally do not need high reliability, and because 

they are operated fewer miles, any repair costs are more spread out over time. 

(2) Motorcoach and Bus Industry 

There are generally three types of motorcoach services: point to point service, fixed 

route and fixed schedule service, and intercity or special event service. Shuttle buses 

are typically used in point to point service, such as transporting passengers to, from, or 

between airports or other points of destination. Shuttle buses are typically light- to 

medium heavy-duty buses and can be powered by gasoline or diesel. Motorcoaches 

are heavy heavy-duty buses designed for long distance travel. They are frequently 

used as charter buses for intercity travel or special event services and do not operate 

on fixed routes or schedules. As these vehicles age, their use tends to change such 

that they are used for shorter trips. 

b) Out-of-state Trucks and Buses 

Staff estimates there are about 490,000 different vehicles operating in California over 

the course of a year. Fleets that come in from out-of-state will vary in age, but have the 

newest vehicles of any other category of vehicles. Most vehicles coming in from outside 

California travel well over 100,000 miles per year. Most of these vehicles would reach 

1,000,000 miles in seven to ten years. Those from neighboring states will also travel 

relatively high miles, but are not as new. Staff did not include the costs attributable to 

out-of-state vehicles in the E-DRAM model analysis because the model does not 

address the impacts of costs occurring outside California. 
-203- 

Figure XIV-1: Vehicles from Non-Neighboring States 

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As Figure XIV-1 shows, the vehicles registered in non-neighboring states have mostly 

newer vehicles. About 80 percent are less than 7 years old and would normally have 

2007 and newer engines by January 1, 2014, thus meeting the proposed PM and BACT 

requirements until 2021. The remaining 20 percent would need to have a verified 

DECS installed or would potentially be replaced earlier than normal. Small fleets from 

non-neighboring states are estimated to represent only about 2 percent of the nonneighboring truck population but typically have the same age distribution as larger fleets 

because of the high number of miles travelled. By 2021, more than 94 percent of these 

vehicles would normally have 2010 emissions engines or newer. Consequently, the 

cost impact of the proposed regulation would be the lowest compared to vehicles in 

other truck categories. 

Staff analyzed IRP registration data from various non-neighboring states in the midwest 

and eastern United States. Staff’s analysis of fleets that reported traveling in California 

showed that about half of the vehicles were in fleets that operated less than 1,000 miles 

per truck in California. Under the proposed regulation, those that operate less than 

1,000 miles per year in California would be exempt from any of the proposed 

performance requirements and would subsequently have no costs. For the remaining, 

vehicles staff estimated that the total increased cost for non-neighboring vehicles would 

be about $471 million. Staff believes this estimate is conservative because larger outof-state fleets have the ability to direct their cleaner vehicles (about 83 percent of the 

vehicles) to California, resulting in no increased cost of operation. 

There are an estimated 40,000 trucks operating in California from neighboring states 

(Arizona, Nevada, Idaho and Oregon. Trucks from neighboring states have nearly 

identical vehicle age distributions to California registered interstate trucks. About 58 

percent of the vehicles are less than 7 years old. Staff estimates that, through normal 

attrition, these vehicles would typically have 2007 and newer engines by January 1, 

2014, thus meeting the proposed PM and BACT requirements until 2021. However, to 
-204- 

meet the proposed NOx and PM performance standards, the remaining 42 percent 

would need to have a verified DECS installed and/or would potentially be replaced 

earlier than normal. But by 2021, staff estimates that more than 90 percent of these 

truck tractors would normally have 2010 emissions engines or newer. Again, in many 

cases like non-neighboring state operators, neighboring out-of-state fleets can direct 

their cleaner vehicles to California to minimize their costs. 

c) California Based Interstate Trucks and Buses 

As Figure XIV-2 shows, the California tractors that are registered in the IRP tend to be 

relatively new. About 58 percent of the vehicles are less than 7 years old. Staff 

estimates that, through normal attrition, these vehicles would typically have 2007 and 

newer engines by January 1, 2014, thus meeting the proposed PM and BACT 

requirements until 2021. However, to meet the proposed NOx and PM performance 

standards, the remaining 42 percent would need to have a verified DECS installed 

and/or would potentially be replaced earlier than normal. By 2021, staff estimates that 

more than 90 percent of these truck-tractors would normally have 2010 emissions 

engines or newer. Consequently, the average cost per truck in this timeframe would be 

lower compared to other truck categories. 

Figure XIV-2: California IRP 

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d) In-state Registered Tractors 

In-state registered tractors operate regionally or locally. There is significant variety in 

the type of vehicles used, including smaller beverage delivery tractors, two axle tractors 

pulling double trailers, or larger three axle tractors. Newer tractors registered to operate 

in-state average about 75,000 miles per year, while 20 year old tractors average about 

30,000 miles per year. Because in-state tractors operate fewer miles than interstate 

registered tractors, it takes longer for them to reach 1,000,000 miles (the estimated end 

of their useful lives). 
-205- 

As Figure XIV-3 shows, in-state registered tractors have a broad age distribution. About 

35 percent of the vehicles are less than 7 years old. Staff estimates that, through 

normal attrition, these vehicles would typically have 2007 and newer engines by 

January 1, 2014, thus, meeting the proposed PM and BACT requirements until 2021. 

However, to meet the proposed NOx and PM performance standards, the remaining 65 

percent would need to have a verified DECS installed and/or would need be replaced 

earlier than normal. But by 2021, staff estimates that more than 60 percent of these 

truck-tractors would normally have 2010 emissions engines or newer. 

Figure XIV-3: California In-state Registered Tractors 

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e) Small Fleets 

Based on 2006 DMV data, fleets with three or fewer vehicles represent almost 90 

percent of the fleets and approximately 48 percent of the trucks registered in California. 

Of these same vehicles, single owner operator fleets represent almost 75 percent of the 

fleets and approximately 32 percent of all trucks registered in California. However, it is 

unclear from the DMV data what proportion of the small fleets are in the transportation 

sector or in other sectors. FleetSeek data identifies owner operators as having about 

14 percent of the revenues and number of trucks within the trucking sector. 

While smaller in-state fleets, in general, tend to have older vehicles compared to larger 

fleets, overall they have similar age characteristics depending on annual miles travelled. 

Similar to larger interstate fleets, California IRP registered owner operators travelling 

higher annual miles have newer vehicles than large fleets operating in state. 

As shown in Figure XIV-4, California IRP registered trucks operated by owner operators 

tend to be fairly new. About 50 percent are less than 7 years old and would normally 

have 2007 and newer engines by January 1, 2014. These vehicles would already meet 

the proposed PM and NOx BACT requirements until 2021. By 2021, about 90 percent 

would have 2010 emissions engines or newer. The age distribution for these fleets 
-206- 

suggests that it is fairly common to purchase 2 to 4 year old vehicles and to operate 

them until they are about 10 years old. 

Figure XIV-4: California Interstate Registered Owner Operators 

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Similar information from the Owner-Operator Independent Drivers Association (OOIDA), 

which primarily represents owner operators and small long-haul trucking companies that 

travel across the country, support these findings. Results of the 2008 Land Line Reader 

Survey, published by OOIDA, show that more than one third of the respondents bought 

their truck new, 65 percent have not owned their truck longer than 6 years and over 80 

percent have not owned their trucks more than 10 years. These results appear 

consistent with the characteristics of the California registered interstate operators. In 

terms of the revenue generated by interstate owner-operators, national surveys of 

interstate independent owner operators who primarily operate in long-haul trucking 

indicate that most independent owner operators generally gross more than $1.50 per 

mile. This is consistent with the reported per mile revenue generated by larger fleets. 

The results are show in the Land Line Reader Survey response shown in Table XIV-3. 

Table XIV-3: 2008 Land Line Reader Survey Results on Gross Income per Mile 

Gross Income per Mile 

% of 

Respondents 

Less than $0.90 5.8 

$0.91 to $0.99 7.0 

$1.00 to $1.24 19.6 

$1.25 to $1.49 29.0 

More than $1.50 33.3 

Blank 5.2 
-207- 

Figure XIV-5: In-state Registered Owner Operator Tractors (Excluding Low 

Mileage Vehicles) 

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While interstate owner-operators tend to have newer vehicles in-state registered 

tractors owned by owner operators are older, with a median age of about 10 years. The 

age distribution for these fleets is shown in Figure XIV-5 and suggests that it is fairly 

common to purchase 5 to 8 year old vehicles and to operate them until they are about 

16 years old. About 28 percent of the vehicles would normally have 2004 to 2006 

model year engines by January 1, 2013, and would be required to install a verified 

DECS under the proposed regulation. An additional 21 percent would be expected to 

have 2007 or newer engines that would already meet the PM and BACT requirements 

until 2021. The remaining 51 percent would need to replace their engines or vehicles 

with one having a 2004-2006 engine and install the highest level verified DECS, or to 

replace it with one having an engine meeting the 2007 engine emissions or newer. By 

2021, staff estimates that about 65 percent of the vehicles would normally have 2010 

emissions engines or newer. 

f) Economic Impact on Transportation Sector 

As was shown in Table XIII-13, the Transportation industry has the highest proportion of 

costs of all the impacted business sectors representing over 50 percent of the estimated 

regulatory costs. Staff estimates the transportation industry would have increased 

regulatory costs of approximately $1.8 billion. 

In evaluating the impacts of these costs, the results of the E-DRAM analysis indicated 

the economic output for the transportation and warehousing sector would be reduced by 

about 0.2 to 0.4 percent in 2013, the highest capital cost year. To put this cost in 

context, the historic California gross domestic product for truck transportation, 

passenger transportation and other support activities is shown in Figure XIV-6. Relative 

to the economic output of this sector, the increased regulatory costs of the proposed 

regulation represents less than 0.1 percent of the cumulative projected gross domestic 

product over the years 2010-2025. 
-208- 

Figure XIV-6: California Gross Domestic Product: Truck Transportation 

As shown in Figure XIV-7, California employment in transportation and warehousing 

grew significantly over the last decade, from about 380,000 jobs in 1994 to over 

430,000 jobs in 2005. More detailed data on jobs within segments of the transportation 

and warehousing sector are not available. The E-DRAM analysis indicates that the 

proposed regulation could reduce California employment in this sector by as many as 

12,000 jobs, or -2.5 percent in 2013, the highest capital cost year. This represents the 

majority of the potential job impacts from the proposed regulation. However, 

employment trends in this industry sector have continued to increase, and staff believe 

such growth can be expected to continue as population in the state continues to grow. 

Therefore, the projected impact on employment would result in slower growth, and 

would not necessarily result in a loss in jobs. 

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-209- 

Figure XIV-7: California Employment: Transportation and Warehousing 

g) Cumulative Costs and Ability to Pass on Costs 

To evaluate potential cumulative costs, as part of the ARB Heavy Duty Vehicle survey, 

staff requested information about off-road diesel vehicles, portable engines, and 

information about the truck and trailer. The truck and trailer information allowed staff to 

determine whether a fleet owner would have equipment that may be subject to an 

existing regulation. 

Out of a total of 682 transportation companies that responded to the ARB Survey, there 

were 105 transportation companies that indicated they were subject to the In-Use OffRoad Vehicle Regulation, the Portable Equipment Regulation or PERP. These 

companies reported the ranges of equipment horsepower that would be subject to the 

other rules as shown in Table XIV-4. 

Of the 105 fleets shown in Table XIV-4 that are subject to multiple regulations, almost 

all of them had less than 2,500 horsepower (hp) of off-road equipment. Under the offroad regulation, such fleets are considered small fleets, meaning they are not subject to 

the replacement requirements, and do not need to meet the PM retrofit requirements 

until 2015. Also, few fleets overall reported having equipment subject to the Portable 

Equipment Regulation. For those that are subject to that regulation, they would have to 

replace their unregulated Tier 0 portable engines by January 1, 2010, which is before 

most fleets subject to the proposed regulation would have to take significant action. 

Since the regulatory compliance timelines do not overlap between these two regulations 

and the proposed regulation, and since few fleets are impacted by these multiple 

regulations, staff does not believe that, overall, many fleets in the transportation sector 

will have to address the issue of cumulative costs with these regulations. 

380

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Employment (1,000 People)
-210- 

Table XIV-4: Percentage of Transportation Fleets Reporting Equipment HP 

Subject to Other Rules 

Off-Road Engine 

Horsepower 

Off-Road 

Vehicles 

Portable 

Engines 

<2,500 hp 12% 8% 

2,500 to <5,000 hp 0% 0% 

>=5,000 hp 1% 0% 

The trucking sector is a competitive industry local, regional and interstate markets. 

Within these markets, trucking companies tend to specialize with certain equipment and 

product transportation for a variety of reasons. These include filling niche demands, 

improved efficiency, customer satisfaction, reliability and expertise required to transport 

various products. In many cases, larger companies depend on owner operators to 

support seasonal needs, variations in work load and a variety of other reasons. 

However, the requirements to install verified DECS or to operate newer trucks will have 

an impact on companies who travel fewer miles and keep their trucks longer. Staff 

believes that, in general, companies will be able to pass through their costs, as the 

incremental increase in revenue per mile is small relative to existing gross revenue 

levels. This is shown below in several actual fleet case studies. Additional case studies 

for other fleets are provided in Appendix J. 

In addition, to the extent fleets subject to the proposed regulation would qualify for 

incentive funding (as discussed in Chapter XV), the anticipated compliance costs would 

be even lower, further reducing the need to pass on costs. 

(i) Refrigerated Transport Case Study 

As a case study, staff analyzed the economic impact of the proposed regulations and 

the existing transportation refrigeration unit regulation for a refrigerated transport 

company that owns 228 tractors and 270 refrigerated trailers used in long haul 

operations. The average tractor age was 7 years and the average trailer age was about 

6 years old. This particular company normally purchases refrigerated trailers new and 

maintains a mix of new to three year old trucks. 

 For this company, staff estimates the increased costs to comply with the proposed 

regulation would be about $1.5 million in 2008 equivalent dollars over the calendar 

years of 2010-2025. This compares to about $16.8 million that would normally be spent 

for capital upgrades of trucks over this time period. Annual revenues for this company 

are approximately $47.8 million, which are cumulatively projected to be $583 million in 

2008 equivalent dollars over the same time period. To offset the increased capital costs 

of the regulation, this fleet would need to increase revenue by about 0.25 percent, or 

$0.0031 per mile, during 2010 to 2030. 

 

This company would also be subject to the transport refrigeration unit (TRU) regulation. 

Staff estimate increased TRU costs of $2.1 million in 2008 equivalent dollars would be 

incurred over 2008-2018 to meet the TRU requirements. Thus, the increased costs of 
-211- 

both rules would be approximately $3.6 million in 2008 equivalent dollars over the 

calendar years of 2010-2025. To offset the increased capital costs of these combined 

regulations, this fleet would need to increase revenue by about 0.61 percent, or $0.0074 

per mile, during 2010 to 2030. 

 

(ii) Motorcoach Case Study 

A California bus company comprised of 138 diesel buses with an average fleet age of 

6.4 years had a 2007 net income of approximately $800,000 out of about $9.8 million in 

gross receipts. This company operates a range of bus types including small shuttle 

buses and motorcoaches. The shuttle buses are primarily operated locally and the 

motorcoaches are used for both local trips and longer trips. On average, this company 

would spend about $1.7 million annually for normal replacements of 11 to 12 vehicles. 

For this company, staff estimates the increased costs to comply with the proposed 

regulation would be about $900,000 in 2008 equivalent dollars over the calendar years 

of 2010-2025. This compares to about $20.1 million that would normally be spent for 

capital upgrades over this time period. Annual revenue for this company is 

approximately $9.8 million, which is cumulatively projected to be $120 million in 2008 

equivalent dollars over the same time period. To offset the increased capital costs of 

these regulations, this fleet would need to increase revenue by about 0.8 percent from 

2010 to 2025. 

2. Agricultural Sector 

The Agricultural sector includes farms and ranches, forestry, farm service providers and 

agricultural processing centers. The gross domestic product data for the agricultural 

sector from the 2006 California Statistical Abstract for 2004 was $26 billion per year. In 

its applicability, the proposed regulation would include agriculture transport vehicles, 

and specific certain others that are owned by chemical supply companies. Agricultural 

services are estimated to add about $1 billion to the gross domestic product of this 

sector. 

As reported August 28, 2008, by the USDA’s National Agricultural Statistics Service and 

Economic Research Service, California agriculture saw a 15 percent increase in the 

sales value of its products in 2007. The state’s 75,000 farms and ranches received 

$36.6 billion for their output in 2007, a 15 percent increase from 2006. 

a) Fleet Characteristics 

ARB staff worked with agricultural stakeholder groups and farmers to develop an 

agricultural fleet specific survey based on the broader statewide survey. Based on the 

results of the agricultural fleet survey, staff estimates that there are about 22,000 

vehicles engaged in agricultural operation in California. However, most farms do not 

own vehicles within the scope of the proposed regulation. Vehicles in this industry 

sector are typically older and drive fewer miles than most other sectors. 
-212- 

While many farms and ranches do not own vehicles that would be subject to the 

proposed regulation because they contract much of their needed transportation 

services, they still own vehicles to support their farm activities and/or to deliver products 

to market. In either case, vehicles used on farms and ranches range from single unit 

vehicles with bodies designed for uses specific to farming operations, to tractor trailer 

combinations for transporting harvested commodities for processing. 

Farm operators, especially those that do not own their own vehicles, depend on custom 

service (for hire) providers for supplies, soil preparation, crop harvesting, and other 

services. Also, most farm operators contract with custom harvesters, farm labor 

contractors, co-operatives, trucking companies that transport commodities to processing 

centers, and often depending on seasonal operators to perform this work. 

While many of the truck bodies installed on trucks used in agricultural operations are 

also available in trailer configurations that can be pulled behind a farm tractor, trucks 

are typically used where farm land is not contiguous and incidental travel on the 

highway is required. There are a number of truck body types that are used in 

agricultural operations for feeding livestock, land conditioning, crop protection chemical 

application, fertilizer spreading, dust control, harvesting and transporting. 

Data for the agricultural industry from the agricultural fleet survey showed an average 

vehicle fleet age of about 16 years. Of the vehicles reported, about 55 percent were 

heavy heavy-duty vehicles and the remainder were medium heavy-duty vehicles. Staff 

compared the results to the 2002 National VIUS survey data, and found that mediumduty California agricultural vehicles appear to be older than the national average, while 

the heavy heavy-duty vehicles are of similar age. 

b) Economic Impact on Agricultural Sector 

As was shown in Table XIII-13 in Chapter XIII, staff estimates the Agricultural Sector 

would have an increased regulatory cost of approximately $265 million. In evaluating 

the impacts of these costs, the results of E-DRAM analysis indicate the economic output 

for the agriculture, forestry, and fishing sector would be reduced by about 0.1 percent in 

2013, the highest capital cost year. To put this cost in context, the historic California 

gross domestic product for the agricultural sector is shown in Figure XIV-8. Relative to 

the economic output of this sector, the increased regulatory costs of the proposed 

regulation represents less than 0.1 percent of the cumulative gross domestic product 

over the years 2010-2025. 
-213- 

Figure XIV-8: California Gross Domestic Product: Agriculture 

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As shown in Figure XIV-9, employment in agriculture has varied significantly over the 

last decade, from about 380,000 jobs in 1994 to over 400,000 jobs in 1997, and 

subsequently reduced to less than 380,000 jobs in 2005. The E-DRAM analysis 

indicates that the proposed regulation would reduce California employment in this 

sector by about 0.1 percent, or 430 jobs in the highest cost year. With the variable 

nature of employment in this sector, staff does not believe the proposed regulation will 

have a noticeable impact on agricultural employment. 

Figure XIV-9: California Employment: Agriculture 

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c) Cumulative Costs and the Ability to Pass on Costs 

Out of a total of 504 agricultural companies that responded to the ARB heavy-duty 

vehicle survey, most had filled out an abbreviated version of the survey which did not 
-214- 

have detailed vehicle information to determine if there fleets are subject to multiple ARB 

regulations for instance, its unclear if some of the trucks reported had refrigeration units, 

questions remain as to address whether some farms also had portable engines or nonfarm use off-road equipment. Staff has committed to addressing emissions from in-use 

off-road agricultural tractors and other equipment in 2010, and plans to evaluate 

cumulative regulatory cost impacts as part of that rulemaking effort. 

Farming is an diverse and complex industry. Various commodities are traded on a world 

market and prices are establish by supply and consumer demand. Supply is often 

affected by weather and other factors. Lower cost commodities produced in other parts 

of the U.S. or in other countries limit the commodity price and the ability to pass through 

costs. However, farmers have historically had the ability to switch to other higher value 

crops as margins and profits for particular commodities decline. This practice is 

expected to continue as market conditions continue to change and the potential need to 

generate additional revenue arises. 

When considering these impacts, it is important to note that California is one of the 

leading agricultural states in the country for exporting high value crops such as nuts, 

flowers and fresh fruit throughout the world. In addition, while many crops are grown in 

other parts of the world, direct competition from the Southern hemisphere is limited 

because of the differing seasons. Staff believes that for some commodities, and in 

particular for high value crops, some ability to pass through or absorb costs exists, but 

likely would vary year to year. 

In addition, to the extent fleets subject to the proposed rule would qualify for incentive 

funding (as discussed in Chapter XV), the anticipated compliance costs would be even 

lower, further reducing the need to pass on costs. 

(i) Almond Farm Case Study 

Staff did not receive financial information from any farms or ranches. Therefore, to 

evaluate specific costs, staff used an economic study from the University of California 

(UC), Davis of a typical almond orchard (UC, 2008). The example almond orchard had 

typical gross returns of $4,200 per acre. The study indicates that a single truck-tractor 

would be needed for an orchard of approximately 125 acres. 

Survey data from an Almond Board survey suggests that a typical farm vehicle would be 

16 years old (a 1992 model year) vehicle and would be driven about 13,000 miles 

(Almond, 2007). If this vehicle would be normally replaced when it was 25 years old it 

would need to be replaced in 2017. Under the agricultural provisions of the proposed 

regulation, this vehicle would be required to be replaced by January 1, 2017. Using the 

same assumptions from the cost model, it is assumed the farmer would normally buy a 

ten year old replacement vehicle. Therefore, if the farmer chose to purchase a vehicle 

with a 2010 model year engine, the farmer would buy a 7 year old vehicle rather than a 

10 year old vehicle. Staff estimates that he would pay about $12,000 more than normal 

to replace this vehicle after accounting for resale value and a potential loss in value of 

the older vehicle. For a farm of this size, the total amount of almonds harvested from 
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2010 to 2025 would be about 7,350,000 pounds, valued at $6,400,000 in $2008. The 

increased capital costs to comply with the proposed regulation represents about 0.025 

percent of the gross revenue received. To offset the increased cost to replace this 

vehicle, the farmer would need to increase prices by $0.001 per pound of almonds. 

Further, if the farmer operated the vehicle less than 10,000 miles, the vehicle would not 

be required to be replaced until 2022. 

3. Construction Sector 

The construction sector in the 2006 California Statistical Abstract is comprised of 

businesses engaged in the construction of buildings, highways and utility systems. In 

addition, many of these businesses are also engaged in the preparation of sites for new 

construction, subdividing land for sale, and building sites. The reported gross domestic 

product for 2004 was $70 billion. 

a) Fleet Characteristics 

The construction sector is a broad sector that contains a wide variety of business types. 

Staff estimates there are about 76,000 vehicles owned by construction firms and 

construction contractors. Construction companies range from a special trade contractor 

with one truck and no off-road equipment, to large road construction and earthmoving 

companies with hundreds of trucks and pieces of off-road vehicles and equipment. 

Vehicle types owned by construction companies range from small service trucks and 

water trucks, to larger tractor trailer combinations to transport aggregate, materials, 

debris, and equipment. Construction companies may also have more specialized 

equipment such as sweepers, drill rigs, and cranes. Companies in this sector also 

include cement truck companies. 

While most construction companies and contractors have trucks, many have little or no 

off-road equipment. For those fleets that do have off-road vehicles, in the ARB 2005 

off-road equipment survey, it was reported that the majority of fleets are small fleets 

(i.e., fleets with very few off-road vehicles), and that the majority of off-road vehicles 

were owned by large fleets (ARB, 2005). Table XIV-5 shows the total off-road vehicle 

horsepower, number of vehicles, and number of off-road fleets by fleet size (small, 

medium and large off-road fleets), as defined in the off-road regulation. 

As Table XIV-5 shows, while over 70 percent of the fleets reported to have 2,500 or less 

horsepower (hp), such small fleets have just over five percent of the total hp of affected 

vehicles. Conversely, less than 15 percent of fleets have total maximum power over 

5,000 hp, but these very large fleets have over 80 percent of the total hp of affected 

vehicles. 
-216- 

Table XIV-5: Total Off-Road Vehicle Fleet Characteristics 

Reported Survey Results 

Size 

Category Fleet Size (hp)* Percent of 

Total hp 

Percentage of 

Off-Road 

Vehicles 

Percentage 

of Fleets 

Large over 5,000 81 72 13 

Medium 2,501-5,000 12 16 16 

Small under 2,500 6 12 71 

* As defined in the in-use off-road vehicles regulations 

Staff used FleetSeek to better understand the impacts of the proposed regulation, and 

to determine the percentage of trucks owned by fleets of different sizes within the 

construction sector. Table XIV-6 shows that special trade contractors have the highest 

number of trucks, while another third are owned by heavy construction companies, 

which staff believes are likely to qualify as large off-road fleets under the in-use off-road 

vehicle regulation. Special trade contractors include roofers, plumbers, drywall 

installers and electricians that are expected have few or no off-road vehicles. 

Table XIV-6: Percent of Vehicles in Construction by Category 

Construction Categories Vehicles 

Special trade contractors 46% 

Heavy construction, except building 33% 

Stone, clay, and glass products 13% 

General building contractors 7% 

All Other 1% 

 Source: FleetSeek 

To verify this data, staff also evaluated available data for large companies with known 

off-road equipment to estimate the number of vehicles in large fleets. Staff analyzed 

data from large fleets with 733 vehicles and a total of 596,000 total off-road vehicle hp. 

Staff estimates there are 27.7 million total off-road vehicle hp in the construction and 

mining sector, with 81 percent of it in fleets with more than 5,000 hp. Using the ratio of 

vehicles to total fleet horsepower, staff estimates that there are less than 23,000 

vehicles, or about a third, are owned by companies that would be considered to be large 

fleets in the off-road regulation. The remaining 53,000 vehicles would be in fleets that 

either would be small fleets or medium fleets in the off-road regulation or have no offroad equipment. Under the off-road regulation, small fleets only have to meet the PM 

filters requirements, and not until starting 2015. 

b) Economic Impact on Construction 

Staff estimates the construction industry would have increased regulatory costs of 

approximately $1 billion in $2008 as a result of the proposed regulation. In evaluating 

the impacts of these costs, the results of E-DRAM analysis indicate the economic output 

for the construction sector would be reduced by about 0.15 percent in 2013, the highest 
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capital cost year. For the California construction sector, staff estimates that the 

increased regulatory costs of the proposed regulation represent 0.13 percent of the 

gross domestic product over the years 2010-2025. The historical California cumulative 

projected gross domestic product for the construction sector is shown in Figure XIV-10. 

Figure XIV-10: California Gross Domestic Product: Construction 

While not reflected in recent data, staff expects that some of this growth has been lost in 

recent years due to poor economic conditions in the industry. While staff expects the 

market will grow in the long term, with the current economic climate, it is less certain 

when the construction economy will recover. The residential construction sector, in 

particular, has been significantly impacted with the recent downturn in the economy. 

The E-DRAM analysis indicates that the proposed regulation would reduce California 

employment by about 0.15 percent, or 1,300 jobs in 2013, the highest capital cost year. 

As shown in Figure XIV-11, employment in construction grew from about 500,000 jobs 

in 1994 to over 900,000 in 2005. However, while not reflected in recent data, staff 

expects that some of this growth has been lost in recent years due to poor economic 

conditions in the industry. While staff expects the market will grow in the long term, with 

the current economic climate, it is less certain when the construction economy will 

recover. The residential construction sector, in particular, has been significantly 

impacted with the recent downturn in the economy. 

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Figure XIV-11: California Employment: Construction

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Staff also evaluated sources of recent construction valuation trends to determine if there 

are differences in growth patterns within construction. Shown in Figure XIV-12 is the 

construction valuation projection made by the Economic Research Unit of the California 

Department of Finance for residential versus non residential construction in a report 

released on April 2008. While quite variable over time, the residential construction 

sector overall is currently experiencing a substantial slowdown. However, the nonresidential sector has not shown a similar decline. For the industry as a whole, the 

forecast projects a recovery for residential construction in 2009 and 2010, and a 

continued upward trend in the non-residential sector. 
-219- 

Figure XIV-12: California Construction Total Valuation Dollars (in billions) 

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c) Cumulative Costs and Ability to Pass on Cost 

Out of a total of 357 construction companies that responded to the ARB on-road survey, 

63 companies indicated they had off-road vehicles or portable engines or both. 

However, the survey responses did not include many large construction companies, and 

therefore staff does not believe the data provided are representative of large companies 

as a whole. Therefore, staff has used alternative means to estimate the anticipated 

cumulative costs of the proposed regulation and existing ARB regulations. 

In evaluating the cumulative impacts of the proposed regulation on the construction 

sector, staff segregated its analysis into large fleets and small fleets. While the 

construction industry sector as a whole could have compliance costs associated with a 

number of in-use regulations, large fleets are expected to have the greatest cumulative 

costs, as they will typically would have the highest compliance costs associated with the 

proposed regulation and recently adopted the off-road regulation. In developing its 

regulatory cost estimates for the in-use off-road vehicle regulation, it was estimated that 

$1.7 billion (about 50 percent of the total costs) was attributed to the construction and 

mining industries. 

In proposing the In-Use Off-Road Diesel Regulation, staff concluded that most 

businesses would be able to pass through or absorb the costs of that regulation. As 
-220- 

discussed above, in evaluating the cumulative costs of this regulation and the in-use offroad vehicle regulation, staff has concluded that overall, the cumulative impact of the 

two regulations is small, increasing the anticipated regulatory costs for affected fleets by 

no more than about 6 percent. As such, staff does not believe that these additional 

costs will change the industry’s ability to pass through the costs of both regulations in 

the form of higher bids. 

In addition, to the extent fleets subject to both rules would qualify for incentive funding 

(as discussed in Chapter XV), the anticipated compliance costs would be even lower, 

further reducing cumulative cost impacts and the need to pass on costs. 

(i) Large Off-Road Fleets 

As noted above, staff did not receive the on-road truck and off-road vehicle information 

from many construction companies necessary to be able to perform a detailed analysis 

on the cumulative industry impacts of multiple regulations. To address this, staff used 

2006 DMV data to find the model year and body type of vehicles owned by individual 

large off-road vehicle fleets for which staff already had off-road equipment information. 

Staff then analyzed the combined compliance costs associated with the off-road 

regulation and the on-road regulation for 10 large construction companies with more 

than 5,000 hp of off-road vehicles each. 

Because staff did not have information about the annual miles traveled by the on-road 

vehicles in these fleets, staff used a conservative estimate by assuming all vehicles did 

not qualify for any of the low-use flexibility provisions in the proposed regulation. The 

companies analyzed had 733 vehicles and a total of 596,000 total hp. Based on this 

analysis, staff has concluded that the combined cumulative costs for large off-road 

fleets to comply with both the proposed regulation and the in-use off-road vehicle 

regulation is about 6 percent higher than the anticipated compliance costs of the in-use 

off-road vehicle regulation alone. 

(ii) Small and Medium Off-Road Fleets 

Small and medium fleets in the in-use off-road vehicle regulation are defined as those 

having less than 5,000 total cumulative off-road vehicle hp. This means, for example, a 

company might have a small fleet of backhoes, or wheel loaders or motor graders. 

Under the off-road regulation, these fleets are not subject to any clean-up requirements 

until 2013 for medium fleets, and 2015 for small fleets. In addition, for small fleets, the 

clean up requirements are less stringent than for higher hp medium and large fleets. 

As noted above, staff did not receive the on-road truck and off-road vehicle information 

from many construction companies necessary to be able to perform a detailed analysis 

on the cumulative impacts of multiple regulations. Despite this, staff evaluated the 

potential cumulative costs of the proposed regulation for small fleets, and does not 

expect that the proposed regulation will impose any significant over lapping costs on 

small fleets. This is because these fleets would not incur any capital costs under the 

off-road regulation prior to 2015, when they would have to begin installing verified 
-221- 

DECS on their off-road vehicles. Because this is later than when these small fleets 

would have to clean up under the proposed regulation, staff believes it is unlikely that 

small fleets would be required to make capital investments in the same year to comply 

with both regulations. In addition, for contractors not subject to the in-use off-road 

regulation at all (estimated to be as much as 60 percent of the fleet), there are no 

cumulative costs at all. 

Like other small fleets, the costs attributable to the proposed regulation depend on 

when a fleet would normally replace its vehicle. Those that purchase newer vehicles 

may experience no cost at all, while those with older vehicles would be required to 

either install verified DECS or to replace their engines or vehicles prior to 2012 or 2013. 

Also, a fleet that purchases a 2007 to 2009 model year engine would not have any 

additional requirements until January 2021. 

4. Manufacturing Sector 

The manufacturing sector is engaged in making new products from raw material or 

assembling parts. This sector includes plants, factories, or mills used to make food 

products, machinery, furniture, equipment and other items. The reported gross 

domestic product for manufacturing in California was $145 billion in 2004. 

a) Economic Impact on Manufacturing 

Staff estimates the manufacturing sector would have a increased capital costs of 

approximately $168 million as a result of the proposed regulation. The results of the EDRAM analysis indicate the output off California manufacturing would be reduced by 

about 0.05 percent in 2013, the highest cost year. The historic California gross 

domestic product for manufacturing sector is shown in Figure XIV-13. Overall, staff 

estimates that the increased total costs of the proposed regulation represent 0.0008 

percent of cumulative projected gross domestic product over the years 2010-2025. 
-222- 

Figure XIV-13: California Gross Domestic Product: Manufacturing 

As shown in Figure XIV-14 employment in manufacturing has declined from about 1.7 

million jobs in 1994 to about 1.5 million in 2005. The E-DRAM analysis indicates that 

the proposed regulation could reduce California employment in the manufacturing 

sector by about 0.05 percent, or 1,000 jobs in the highest cost year. 

Figure XIV-14: California Employment: Manufacturing 

b) Ability to Pass on Costs 

The manufacturing sector has local, regional, and international markets. The ability to 

pass on costs will be determined by a number of factors including the market region, 

uniqueness of a product, supply and consumer demand. Because the use of vehicles 

subject to this regulation in this sector is generally necessary not to generate revenue, 

but to support other revenue generating activities, staff believes these fleets should be 

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-223- 

able to pass on the costs of the proposed regulation through higher prices for the 

products they manufacturer. In addition, to the extent fleets subject to the proposed 

regulation would qualify for incentive funding (as discussed in Chapter XV), the 

anticipated compliance costs would be even lower, further reducing the need to pass on 

costs. 

5. Retail and Wholesale Trade Sector 

The retail and wholesale trade sector primarily sells products to individuals or 

businesses. Retail generally refers to the sale of merchandise in small quantities, such 

as grocery, department, specialty, and apparel stores among other venues. Wholesale 

mainly refers to sales of goods in large quantities to distributors, manufacturers and 

retailers. The California gross domestic product for the retail and wholesale trade sector 

in California was $194 billion in 2004. 

a) Fleet Characteristics 

Goods are either transported using the vehicles owned and operated by the retailer or 

wholesalers, or through the service of a trucking company. Goods are generally 

transported to distributors using tractor trailer combinations and singe unit box trucks. 

For perishable goods, tractors with a refrigerated trailer and tractor, or a single unit 

refrigerated box truck are used. Shipments of raw materials to other manufacturers for 

refinement are typically transported using tractor trailer combinations, flatbed, box 

trucks, tank trucks and others. Some retail stores also own vehicles to provide home 

delivery services. 

b) Economic Impact on Retail and Wholesale Trade 

Staff estimates the retail and wholesale trade sector would have an increased 

regulatory cost of approximately $510 million. In evaluating the impacts of these costs, 

the results of the E-DRAM analysis indicate the economic output for retail and 

wholesale trade would be reduced by about 0.01 to 0.03 percent in 2013, the highest 

capital cost year. To put this cost in context, the historic California gross domestic 

product for the retail and wholesale trade sector is shown in Figure XIV-15. Relative to 

the economic output of this sector, the increased regulatory costs of the proposed 

regulation represents less than 0.1 percent of the cumulative projected gross domestic 

product from 2010-2025. 
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Figure XIV-15: California Gross Domestic Product: Retail and Wholesale 

Trade 

As shown in Figure XIV-16, employment in retail and wholesale trade grew significantly 

over the last decade, from about 1.9 million jobs in 1994 to over 2.3 million jobs in 2005. 

The E-DRAM analysis indicates that the proposed regulation could reduce California 

employment in this sector by about 0.02 percent, or 500 jobs, in 2013, the highest cost 

year. 

Figure XIV-16: California Employment: Retail and Wholesale Trade 

c) Ability to Pass On Costs 

Fleets in the retail and wholesale industry sector are not as significantly affected with 

other ARB regulations as other industries. Because the use of vehicles subject to this 

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-225- 

regulation in this sector is generally necessary not to generate revenue, but to support 

other revenue generating activities, staff believes these fleets should be able to pass 

through the costs of the proposed regulation through higher prices for the products they 

market and sell. 

In addition, to the extent fleets subject to the proposed regulation would qualify for 

incentive funding (as discussed in Chapter XV), the anticipated compliance costs would 

be even lower, further reducing the need to pass on costs. 

6. Schools Districts and School Transportation Providers 

School districts are generally responsible for providing school transportation. While 

many school districts purchase buses and hire their own drivers, many others engage 

the service of school transportation providers (such as Laidlaw) to perform this function. 

Districts operating their own school bus system may charge fees for school bus 

ridership. In some urban locations, students may utilize public transit services. 

In the United States, the school bus is a vehicle which is built and equipped according 

to federal and state laws that are required to be painted yellow. Most school buses 

made in recent years have been diesel-powered or hybrid. Full-size school buses can 

seat 59 to 90 passengers, but in many districts smaller vehicles are also used. Such 

smaller vehicles are often used for low-density routes associated with private schools 

and for magnet programs, as well as those for developmentally-challenged students. 

Today there are about 3,700 verified DECS currently installed on both public and private 

school buses in California and an additional number that are equipped with OEM 

equipped DPFs. However, staff estimates that there are about 3,500 publicly-owned 

and over 3,900 privately-owned school buses needing to be retrofit to comply with the 

proposed regulation. 

About $200 million is available in the Lower Emission School Bus program for bus 

replacement and retrofit. The program provides up to $20,000 for a verified DECS, 

including 10 years of maintenance cost for 1987 and newer buses. This money is 

available to both school districts and private school transportation providers. Up to 

$140,000 is also available for replacement of pre-1987 buses, but only for the purchase 

of public school buses. Also, up to 10 percent of the award amount is available for 

infrastructure improvements for alternative-fueled buses. Local air pollution control 

districts administer the funds, and the availability of incentive funding is dependent on 

funding choices made by school districts and program administrators. 

a) Economic Impact on School Districts 

Staff does not expect the proposed provisions for school buses to have a significant 

impact on school districts or school transportation providers. Taking into consideration 

$200 million that are available through the Lower Emission School Bus program for bus 

replacement and retrofit, the remaining regulatory costs only total about $27 million over 
-226- 

8 years (2010-2017). Staff believes affected school districts and transportation providers 

should be able to absorb these costs into their existing budgets. 

7. Federal Fleets 

The federal government is the largest public truck/bus fleet operator in California. 

According to the 2006 Federal Fleet Report, the federal government owned and 

operated over 18,900 heavy-duty vehicles and buses nationwide, excluding military 

vehicles. About 12 percent of these vehicles are estimated to operate in California. 

The U.S. Postal Service (USPS) accounted for over 28 percent of these vehicles, and 

the Department of Interior operated over 23 percent (GSA, 2007). The remaining 

vehicles were operated by various other agencies. The average ages of the mediumand heavy-duty vehicles are 6 and 9 years respectively (GSA, 2007). 

The federal government operates a wide range of vehicle types based on the needs of 

each individual agency. For example, the USPS operates vehicles such as tractor 

trailers and dry vans for transporting letters and packages between distribution centers, 

and smaller vans for delivering packages to business and residences. The U.S. Forest 

service, an agency of the Department of the Interior, operates larger heavy haul 

vehicles for transporting forestry equipment, and smaller chipper trucks for clearing 

trees and bushes. In addition, for scenic locations such as in national parks, tour buses 

may be used for transporting visitors. In support of all of the federal governments’ 

operations, a wide range of vehicles are used for transporting personnel, site 

maintenance and for general operations. 

a) Economic Impact on Federal Fleets 

Staff met with representatives of the General Services Administration (GSA) to discuss 

the proposed regulation and to discuss compliance options. GSA representatives 

indicated they would likely allocate 2007 and newer vehicles in the federal fleet to 

California to meet the PM requirements from 2011 to 2014 rather than installing verified 

DECS. After 2014 they would resume their normal vehicle replacement cycles and 

would meet the 2021 PM and NOx requirements without any accelerated replacements. 

The anticipated costs to the federal government are expected to be negligible. 

D. Economic Impact on California Consumers 

To estimate the economic impact of the proposed regulation on consumers, staff 

estimated a high and low range cost based on the total economic impact in the state. 

While the actual costs could be higher or lower for a given product, the estimate 

provides a reasonable indicator of the average cost impacts. For the low end cost 

range, staff estimated the consumer impact by calculating the average increase in cost 

compared to the total gross domestic product for California from 2010 to 2025. For the 

high end cost range, staff compared the annual gross domestic product for the highest 

cost year. 

Overall, in the context of the State’s $3.1 trillion economy, the economic impact of the 

proposed regulation is minor and is not expected to impose a noticeable impact on 
-227- 

consumers. However, if all of the regulatory costs were passed through to consumers, 

staff estimates this could result in an increase in consumer goods of about 0.04 percent 

in the highest cost year (2013), and about 0.014 percent on average over the life of the 

proposed regulation. To put this into context, this equates to about a 1 to 2 cent 

increase for a pair of shoes, less than one one-hundredth of a cent increase per pound 

of produce, or an increase of from $3 to $10 for a new car. 

E. References 

GSA, 2007. GSA Office of Governmentwide Policy. Federal Fleet Report, Fiscal Year 

2006; January 31, 2007. 

2006 California Statistical Abstract, January 2007.

USDA 2008. USDA’s National Agricultural Statistics Service and Economic Research 

Service, August 28, 2008. 

UC, 2008. UC Davis 2008 study #AM-VS-080-1. 

Almond, 2007. Almond Board of California. 2007 Almond Almanac. 

ARB, 2005. California Air Resources Board. 2005 ARB Off-road Equipment Survey, 

Completed February 2006. 

http://www.arb.ca.gov/msprog/ordiesel/documents/Inventory_Updates_OffRdEquip_07_

12.pdf
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-229- 

XV. AVAILABILITY OF INCENTIVE FUNDING

The role of incentive funding will be an important element for many fleets as they 

consider how to comply with the proposed regulation. While staff recognizes the 

demand for incentive funding greatly outweighs the availability of funds, several 

potential state, federal and local funding programs exist that could assist with offsetting 

the cost of the proposed regulation to affected fleets that move quickly to take 

advantage of these funding opportunities. 

A. State Sources of Funding 

State incentive funding programs have historically played a complementary role to the 

state’s regulatory emission reduction programs towards meeting the state’s SIP 

requirements and achieving California’s air quality goals. California’s funding programs 

typically require participation prior to established regulatory deadlines; thus to qualify, 

fleets affected by the proposed regulation will need to act quickly if they are interested in 

pursuing available state incentive funding. 

1. Proposition 1B Funding 

In 2006, California voters approved the Highway Safety, Traffic Reduction, Air Quality, 

and Port Security Bond Act of 2006 (Proposition 1B). This measure authorized the 

California Legislature to appropriate $1 billion for emission reductions in the State’s 

good movement corridors. Proposition 1B funds are used to pay for projects that are 

completed in advance of or go beyond what is required by any regulation or law. 

a) Overview 

The ARB’s Proposition 1B: Goods Movement Emission Reduction Program (Prop. 1B 

Program) implements Senate Bill 88 (Chapter 181, Statutes of 2007) as amended by 

Assembly Bill 201 (Chapter 187, Statutes of 2007), which directs ARB to quickly reduce 

emissions and public health risk associated with freight movement along California’s 

trade corridors – the Bay Area, Central Valley, Los Angeles/Inland Empire, and San 

Diego/Border area. 

In approving the Prop. 1B Program, the Board has targeted $360 million to provide 

incentives to clean-up heavy-duty vehicles (those not routinely serving seaports or 

intermodal rail yards). Eligible upgrades include retrofits, repowers, and replacements 

with funding in the form of grants for purchase or lease-to-own programs. The 

Proposition 1B ballot language directs ARB to fund emission reductions not otherwise 

required by law or regulation. Once the Board adopts a regulation, upgrades eligible for 

funding must result in early reductions in advance of the BACT compliance date or 

achieve extra reductions beyond what is required in the BACT requirements. 

For most fleets, the current Prop. 1B Program requires engine repowers and vehicle 

replacements to be completed three years before required. However, independent 

owner/operators and owners of MY 1997 and older vehicles need to complete the 

project only two years earlier than otherwise required. The funding is currently limited to 
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2003 model year vehicles and older. Each vehicle then competes for funding based on 

the emission reductions to be achieved and the cost-effectiveness. These factors favor 

replacement of the oldest vehicles. 

The Prop. 1B Program Guidelines for fiscal year (FY) 2007-08 funds allow up to the 

following: 

• $5,000 to retrofit a truck with a verified Level 3 DECS; 

• $20,000 for an engine repower; 

• $50,000 to replace a model year 2003 or older vehicle with one meeting 2007 or 

better new engine standards. 

The current Prop. 1B Program Guidelines require vehicle replacements to be completed 

at least 3 years prior to a regulatory BACT requirement for that level of emissions 

control. For independent owner/operators and owners of MY1997 or older vehicles, 

replacements must be completed 2 years prior to the BACT requirement. Vehicles 

receiving Prop. 1B Program funding are prohibited from participating in fleet averaging 

programs during this advance period. The Prop. 1B Program Guidelines also require 

that the upgraded vehicle be able to legally operate in California for four years with 

retrofits to eight years for replacements and repowers to sustain the benefits of the 

investment. 

b) Current Funding 

Of the $1 billion authorized under Proposition 1B, ARB received the first installment of 

$250 million in the FY 2007-2008 budget, and the second $250 million installment in the 

FY 2008-2009 budget. The Figure XV-1 below shows the Board’s allocation of 

FY 2007-2008 funds. 
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Figure XV-1: Proposition 1B Fiscal Year 2007/2008 Allocation 

Harbor Craft, 

$4,300,000

Shore Power, 

$5,400,000

Other Trucks, 

$103,200,000

Locomotives, 

$16,500,000

Port/Rail Yard 

Trucks, 

$117,300,000

Local agencies have already awarded most of the $103 million in FY 2007-2008 funds 

allocated for other vehicles to the most competitive vehicle projects. The overwhelming 

majority of the applications has been for vehicle replacements, with demand for funds 

exceeding four times the available funds in the first year of the Prop. 1B Program. 

Most of the implementing local agencies are developing lease-to-own truck programs 

for expenditure of FY 2007-2008 funds or subsequent cycles. These lease-to-own 

programs provide a mechanism for independent and small fleet owners to obtain a new 

vehicle for a reasonable monthly payment that covers the difference between the 

Program grant and the total vehicle purchase cost. Staff must approve the terms of any 

proposed lease-to-own programs to ensure that the payments are reasonable and 

appropriate. 

c) Program Updates 

ARB staff is currently developing updates to the Prop. 1B Program Guidelines for 

FY 2008-2009 funds through a public process throughout Fall, 2008. The Board is 

scheduled to consider the proposed guidelines during its January, 2009, meeting. After 

soliciting applications from local agencies and discussing funding recommendations in a 

public process, staff expects the Board to award the second $250 million in funding in 

Spring, 2009. Staff will be recommending that most of the funds again be allocated to 

port trucks and other trucks, in recognition of the need for funds and the expected nearterm regulatory deadlines. Local agency funding for individual projects should begin 

later in 2009. 

Staff is evaluating the updates needed to the Prop. 1B Program Guidelines, including 

changes to integrate Program funding options with the proposed regulation. These 

potential changes that staff is developing for discussion in the public process include: 
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• Expansion of the schedule flexibility currently provided for independent 

owner/operators to also include small fleets of 3 or less vehicles (ability to use bond 

funding 2 years prior to regulatory BACT requirement). 

• Mechanism to provide an advantage to vehicles owned by small fleets of one to 

three trucks in the competitive process for funding. 

• Option to allow some medium heavy-duty vehicles engaged in goods movement to 

compete for funding. 

• Alternative calculation of emission reductions based on hours of operation (rather 

than miles traveled) to allow construction industry vehicles to compete for funding. 

• Update to the funding amounts to encourage vehicle replacements with models 

meeting 2010 emission standards and to recognize the potential availability of more 

effective combined PM/NOx retrofit devices. 

• Addition of a combined grant/loan guarantee program. 

The changes identified above would expand the number of vehicles eligible for the 

Prop. 1B Program and recognize small fleets of one to three trucks as a priority for 

funding (along with the oldest trucks already targeted). 

Based on these changes and the BACT compliance dates in the proposed regulation, 

truck owners could compete for bond funding to install PM filters on a 1995-2006 

engine, or to replace or repower a 2003 or earlier engine. PM filters would need to be 

installed in the 2009-2012 timeframe, depending on engine model year. Vehicles in 

fleets of three or less vehicles would generally be eligible for replacement funding 

through the 2010-2012 timeframe, depending on the age of the vehicle. Fleets with 

more than three vehicles would generally be eligible for bond funding through 2012, 

based on the age of the old vehicle. 

2. Lower Emissions School Bus Program 

California’s Lower-Emission School Bus Program (LESB Program) is administered by 

ARB and is implemented by the local air districts. The LESB Program supports the 

retrofit and replacement of public school buses, and the retrofit of school buses 

operated by private companies contracted by public schools to provide home-to-school 

transportation. 

The LESB Program was appropriated $200 million by the Legislature in 2007, and the 

LESB Program guidelines were updated in early 2008. Qualifying projects are allowed 

up to $20,000 for a verified DECS, including 10 years of maintenance costs for 1987 

and newer buses. Up to $140,000 is also available for replacement of pre-1987 buses. 

Up to 10 percent of the award amount is also available for infrastructure improvements 

for alternative-fueled buses. It is anticipated that over 1,100 replacements and 3,500 

retrofits could be funded through the LESB Program. 
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3. Carl Moyer Program 

a) Overview 

Created in 1998, the Carl Moyer Program provides incentive grants to encourage the 

voluntary purchase of cleaner-than-required engines and equipment that provide early 

or extra emission reductions. Eligible projects include cleaner on-road, off-road, marine, 

locomotive and stationary agricultural pump engines. The program achieves near-term 

reductions in emissions of NOx, PM, and ROG. While regulations continue to be the 

primary means to reduce emissions, the Carl Moyer Program plays a complementary 

role by funding surplus emission reduction projects. 

Over its first seven years, the Carl Moyer Program provided $170 million to clean up 

approximately 7,500 engines throughout California. This achieved emission reductions 

of about 24 tons per day of NOx and one ton per day of toxic diesel PM. Legislation in 

2004 provided the Carl Moyer Program with up to $140 million per year through 2015. 

Though significant, this level of funding is far from sufficient to pay for all the reductions 

needed to provide clean air. Reductions required by regulations, and funded by owners 

of affected equipment, must continue to provide the majority of emission reductions. 

On-road projects in the Carl Moyer Program generally consist of new alternative-fuel 

purchases, fleet modernization (replacing an older vehicle with a new or newer vehicle), 

engine repowers, and retrofits. In recent years, fewer on-road projects have been 

funded relative to other categories such as off-road. New purchase projects are not 

common because of a lack of eligible engines that are cleaner than existing standards. 

Repower projects are limited due to physical and technological constraints with 

installing a newer engine in an older chassis. Fleet modernization projects have 

provided significant emission reductions in some areas, but are more difficult to 

administer and may only be considered in air districts that have an approved ARB Fleet 

Modernization Plan. Currently, Fleet Modernization Plans are approved for the South 

Coast AQMD, Sacramento Metropolitan AQMD and San Luis Obispo APCD. 

State law requires that Carl Moyer Program projects provide emission reductions early 

or beyond what is required by regulation. Therefore, on-road projects must be surplus 

to the proposed regulation, as well as existing regulations such as the Fleet Rule for 

Transit Agencies, the Fleet Rule for Public Agencies and Utilities, the Solid Waste 

Collection Vehicle Regulation, and the Port Truck Regulation. 

In order for a project to be considered surplus, the 2005 and 2008 Carl Moyer Program 

Guidelines require a minimum three year project life which means that incentive funds 

can not be used to pay for equipment that is less than three years from its compliance 

deadline. The three year surplus requirement is a fundamental component of the Carl 

Moyer Program and is necessary to ensure that funds are used for early reductions 

rather than paying for compliance. It has only been shortened by the Board in one other 

regulatory proposal. However, as discussed below, staff believes it is appropriate to 

shorten the minimum project life from three years to two years for one component of this 

regulation. Also, projects must also be surplus to the assumptions in the emission 
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benefit analysis performed to determine creditable emission reductions in the SIP. In 

other words, projects funded through the Carl Moyer Program can not double count 

emission reductions claimed by a regulation. 

b) Proposed Changes to the Carl Moyer Program Guidelines 

Based on the proposed regulation, future opportunities for funding on-road projects 

through the Carl Moyer Program will be limited. This section describes those 

opportunities and proposes several changes to existing Carl Moyer Program Guidelines 

that would maximize funding options while ensuring surplus emission reductions. 

These changes will be presented to the Board as part of staff’s presentation of the 

proposed regulation. 

Under the proposed changes, in general, small fleets of up to three vehicles would be 

eligible for incentive funding through the end of 2010 to comply with the 

December 31, 2012, compliance deadline. The first vehicle in a small fleet would be 

eligible for incentive funding for a 2010 truck through the end of 2012. Limited use 

agricultural vehicles would be eligible through 2013, and low use or specialty 

agricultural vehicles would be eligible through 2019. Large fleets with more than three 

vehicles have few remaining funding opportunities that are surplus to the proposed 

regulation. 

In order to effectively integrate Carl Moyer Program funding options with the proposed 

regulation, as well as provide greater consistency with Prop. 1B Program funding, staff 

proposes several changes to the Carl Moyer Program Guidelines. These changes, 

shown below in Table XV-1 would primarily help small fleets purchase newer vehicles 

prior to the compliance deadlines while ensuring that Carl Moyer funded projects result 

in surplus emission reductions. 
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Table XV-1: Proposed Carl Moyer Program Guidelines Changes 

Guideline Provision Existing Criteria Proposed Criteria 

On-Road Fleet Modernization 

Eligible engine and chassis 

model year for old vehicle 1990 and older 1993 and older 

Maximum eligible funding 

80 percent of vehicle cost for 

fleets of 5 or less; 50 percent for 

fleets of 6 or more 

80 percent up to $50,000 per 

vehicle with engine certified to 

1.2 g/bhp-hr standard; 

80 percent up to $75,000 per 

vehicle with engine certified to 

0.2 g/bhp-hr standard. 

Two vehicles to one option not available 

Replacement of two similar 

older vehicles with one newer 

vehicle 

Minimum Project life 3 years 2 years for small fleets 

complying with 2012 deadline 

On-Road Retrofit 

Eligible engine model years no restriction 

2004 or later for small fleets; 

2005 or later for large fleets 

(requires highest level retrofit 

verified for specific engine) 

Agricultural Vehicles 

Reporting to ARB None 

Must obtain the agricultural 

vehicle designation from ARB 

before applying 

All On-Road Carl Moyer Program Funded Projects

Funding contract restriction 

on proposed regulation 

compliance options 

None 

Applicant must use BACT 

Compliance Schedule, not 

BACT Percentage Limits or 

Fleet Averaging, for 

compliance during the contract 

term 

The changes proposed above will expand eligibility for fleet modernization projects by 

allowing replacement of three additional model year engines, 1991-1993. However, the 

focus of this funding would still be on replacing the oldest vehicles. In general, since 

older vehicles that accumulate the most mileage are the most cost effective to replace, 

the most competitive on-road projects are expected to be in small fleets with relatively 

high mileage. 

As a direct result of the anticipated oversubscription of fleet modernization funds, staff is 

also proposing to lower the amount of funding per vehicle to increase the number of 

applicants receiving funds. Similarly, adding a two vehicle to one option under fleet 

modernization provides greater funding options for applicants. 

Changing the minimum project life from three years to two years for small fleets 

complying with the 2012 compliance deadline extends the window of time to fund 

surplus projects in fleets with the greatest need. The 2012 compliance deadline for 
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small fleets is aggressive due to their financial conditions, but necessary to achieve the 

needed emission reductions. A three year project life would require project completion 

by the end of 2009, allowing only one funding cycle. A two year project life allows 

funding during two cycles, and allows districts without a Fleet Modernization Program 

the time to initiate one. 

Staff also proposes to restrict retrofit funding to 2004 and later engines so that retrofits 

are not installed in vehicles destined for short term replacement. 

c) Funding Opportunities under the Carl Moyer Program 

As discussed above, there are limited options available for on-road Carl Moyer Program 

funding. However, considering the Carl Moyer Program Guideline changes proposed 

above, Table XV-2 below describes the future funding options expected after adoption 

of the proposed regulation. 

Table XV-2: Future Carl Moyer Program On-Road Funding Options 

Project Type Funding Availability 

Fleet Modernization - Small Fleets Through 2010; limited for first vehicle only through 

2012 

Fleet Modernization - Large Fleets None 

Retrofits - Small fleets Limited to 2004-2006 vehicles through 2009 

Retrofits - Large fleets Limited to 2005 and 2006 vehicles through 2009 

Agricultural Vehicles – Low Use & Specialty 

(<10,000 miles per year) 

Agricultural Vehicles – Limited Use 

(>10,000 miles/year and <15,000 miles/year 

Fleet modernization through 2019 

Fleet modernization through 2013 

Solid Waste Collection Vehicles – New Purchase 

of 0.84 g/bhp-hr NOx or cleaner 

Through 2009 

Fleet modernization funding would be available for the first, second, and third vehicle in 

small fleets through 2010, two years in advance of the 2012 compliance deadline. For 

the first vehicle only, the emission benefit calculations assume the purchase of a 2007 

truck. Therefore, very limited funding is available for the purchase of a 2010 truck 

through the 2012 deadline. For large fleets, there are no remaining fleet modernization 

or repower funding options that would be surplus to the proposed regulation. 

On-road retrofit options would remain available through 2009, but would be very limited 

because there are few currently verified DECS for 2004 and newer diesel engines. If 

future retrofit devices are verified to achieve NOx reductions sufficient to meet the 2004, 

2007, or 2010 MY NOx Emissions Equivalent definitions in the proposed regulation, 

then those devices would also be eligible for Carl Moyer Program funding in some 

applications. For example, funding could be available through 2017 for verified DECS 

that achieve at least 70 percent NOx reduction on model year 2007-2009 vehicles in 

large fleets. 
-237- 

Designated agricultural vehicles that operate below 10,000 miles annually and specialty 

agricultural vehicles will have funding opportunities through 2019. However, due to 

lower usage and cost, funding for these vehicles may be limited. MY 1993 and older 

vehicles operating up to 15,000 miles annually will be eligible through 2013. 

While not covered under the proposed regulation, funding is also available for new 

purchases of 2007 and newer solid waste collection vehicles, as long as the owner is in 

compliance with the Solid Waste Collection Vehicle Regulation. New purchases must 

be at least 30 percent cleaner than the current 1.2 g/bhp-hr NOx standard. 

4. Assembly Bill 118 Grants 

Assembly Bill (AB) 118 created two new incentive programs with potential funding for 

on-road heavy-duty vehicles. The first is the Alternative and Renewable Fuels and 

Advanced Technology Program to be administered by the California Energy 

Commission, and the second is the Air Quality Improvement Program (AQIP) to be 

administered by ARB. The Energy Commission program will have about $120 million 

annually beginning in FY 2008-09 and is geared toward transforming California’s fuel 

and vehicle types to help attain California’s climate change goals. The AQIP has about 

$50 million annually beginning in FY 2008-2009 to improve California’s air quality by 

funding vehicle and equipment projects, air quality research, and advanced energy 

technology workforce training. 

AB 118 provides the Energy Commission and the AQIP with over seven years of 

program funding. AB 118 requires that grants received pursuant to these two programs 

must achieve emission reductions that are early or go beyond what is required by 

regulation. ARB and the Energy Commission are currently developing guidelines and 

eligible project categories for their respective programs, with initial year project 

solicitations expected in mid-2009. As discussed in the next section, the State’s 

FY 2008-2009 budget designates that the $48 million available in year one be made 

available for loans to aid heavy-duty vehicle owners that would be impacted by the 

proposed regulation. 

5. Concepts for Financing Incentives 

In developing the proposed regulation, staff recognizes that the proposal must be 

balanced in such a way that the needed emission reductions and health benefits are 

achieved, while the State’s economy, and the businesses that support it, can continue 

to grow. As such, it is important that the State take a leading role in ensuring that 

economic assistance is available for fleets affected by the proposed regulation. 

To carry out that role, ARB is developing a heavy–duty vehicle air quality loan program 

with funding provided from two separate but complementary legislatively-established 

sources: Prop. 1B and AB 118. The FY 2008-2009 state budget contains an 

approximate $48 million appropriation to fund a heavy-duty vehicle air quality loan 

program. Funding for loans from the Prop. 1B program is still to be determined. 
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Together, these funding sources will be leveraged to provide critical financial assistance 

options, including finance packages that combine grant and loan funds, to a broad 

range of qualifying fleets operating throughout California. 

a) Applicant Profile 

Just as the existing grant programs described above have their respective eligibility 

criteria, ARB’s proposed loan program also targets a specific subset of the trucking 

industry. The fleets targeted by the loan program are based on the statutes that 

authorize the funding sources, and primarily consist of heavy-duty vehicle owners for 

which it is difficult to qualify for conventional financing through traditional banking 

avenues. That is, ARB’s proposed loan program is not intended to provide lending to 

those that already have established a strong credit history and that could easily qualify 

for a conventional loan, nor is it intended to provide loans to those that have extremely 

poor credit with an assumed high risk of default. The program is intended for the “near 

bankable” -- those that have marginal credit (See Table XV-3). 

It should be noted that the current economic climate has expanded the window of credit 

risk to now include what may have previously been considered “Good”. Also, the table 

below is intended simply to illustrate the portion of the credit risk spectrum on which the 

loan program intends to focus. The actual loan evaluation process will be dependent on 

the respective financial institutions. 

Table XV-3: Credit Risk 

Additional criteria also include, but are not limited to, fleet size (focusing on the smallest 

fleets), corridors and regions of operation, financial hardship, and cost effectiveness. 

b) ARB’s Proposed Loan Program 

Staff is proposing that loan funds be made available for: 1) used and new vehicle 

purchases; 2) ARB-verified DECS; and 3) SmartWay-approved energy efficiency 

retrofits. The following list provides examples of possible equipment packages, and the 

corresponding estimated total costs of those packages, that may qualify for loans 

through the proposed ARB loan program: 

 SmartWay packages (includes used/new trailer transactions) 

• Tractor low-rolling resistance tires (LRRT): $4,750 

• Compliant trailer retrofit (LRRT and aero kits): $6,000 

• New SmartWay-compliant trailer: $28,000 

Credit Risks FICO 

Bankruptcy 

or Collection 

Delinquent 

by 30 days 

Delinquent 

by more 

than 60 

days 

Number 

of Years 

in 

Business 

Loan-tovalue of 

collateral 

(%) 

Debt-toincome 

ratio (%) 

Debttoworth 

ratio 

GOOD >700 N N N >5 <70 <30 1:1 

MARGINAL 

620-

680 N Y N <3 71-80 31-60 3:1 

POOR <600 Y Y Y <3 >80 >60 >3:1 
-239- 

 DPFs ~ $10,000 - $25,000 

 Used/New Vehicles 

• Used MY 2004 tractor: $45,000 

• Used MY 2007 tractor: $80,000 

• New SmartWay-certified MY 2010 sleeper-cab tractor: 

$125,000 (price estimated in 2010) 

• New Day cab tractor – MY 2010 tractor: $115,000 (price 

estimated in 2010) 

 Any combination of the above 

ARB is proposing to utilize the California Pollution Control Financing Authority’s 

(CPCFA) California Capital Access Program (CalCAP) to leverage Proposition 1B and 

AB 118 funds to support affordable financing to vehicle owners to achieve early 

compliance with regulatory requirements. The concept is geared to the typical CalCAP 

borrower (near bankable) and is not intended to provide funding to high risk borrowers. 

c) Potential Applicant Process 

(i) Grant Funding Process 

Because Carl Moyer Program grants are administered by California’s local air districts, 

and Prop. 1B Program grants are awarded by local air districts and other local agencies 

(such as Port Authorities), the grant application process and requirements may vary 

from agency to agency. Though different local air districts and local agency application 

processes may vary, grants are generally awarded through the Carl Moyer Program and 

the Prop. 1B Program on a competitive basis. After the district or agency receives 

funding from ARB, the district or agency announces to the public that program funds are 

available and issues a request for proposals. Applicants then complete and submit their 

applications and supplemental documentation before the close of the application period. 

The district or agency reviews the applications received, and scores the projects 

according to their established ranking criteria. Typical ranking criteria include cost 

effectiveness and benefits to impacted communities. The district or agency enters into 

contracts with the applicants whose projects were highest-ranked. The grantees agree 

to comply with the contract for the term of the project. 

(ii) Loan Funding Process 

The California Pollution Control Financing Authority administers the CalCAP, which 

encourages banks and other financial institutions to make loans to small businesses. 

CalCAP is a form of “loan portfolio insurance” that provides up to 100 percent coverage 

on certain loan defaults. The borrower and lender each contribute a small percentage 

of the principle amount of the loan, which CalCAP matches and places in a “loan loss 

reserve account” at the lender bank. As the lender enrolls more loans, the loan loss 

reserve account grows. The participating financial institutions are entirely liable for loan 
-240- 

losses, which can be reimbursed through each lender’s CalCAP loan loss reserve 

account. From the beginning of the program in 1994 through the end of 2007, CalCAP 

has enrolled over 6,800 loans, with a default rate of less than 4 percent. 

A small fleet owner or owner/operator may or may not receive a grant award through 

the competitive processes explained above. Regardless of whether they are a grant 

recipient, an owner/operator can apply for financing under the CalCAP program. To do 

so, the potential borrower would speak with a loan officer at a bank or financial 

institution that participates in CalCAP. Approximately 60 financial institutions, with 

locations across the state, currently participate in CalCAP. The most current list of 

lenders and their contact information is available at: 

http://www.treasurer.ca.gov/cpcfa/calcap/institutions.pdf. 

The loan officer would assist the borrower in completing the lender’s standard loan 

application. If the lending institution cannot offer the borrower a loan because the 

borrower falls just outside their traditional underwriting standards, the loan officer could 

then evaluate the borrower for eligibility under CalCAP by completing CalCAP’s loan 

enrollment application and ARB’s borrower eligibility criteria and certification form. If the 

borrower meets the CalCAP eligibility criteria, and the lender determines that the 

borrower qualifies for a loan with CalCAP’s backing, the borrower and lender complete 

the lender’s traditional loan issuance process and maintain the lender/borrower 

relationship throughout the term of the loan. 

Except for the small amount of extra information for the borrower eligibility and criteria 

certification form, ARB staff expects very little additional effort on the borrower to 

participate in the CalCAP program, compared to traditional loan financing. 

B. How an Integrated Grant and Loan Program Could Assist Fleets 

Constraints on the availability of grant funds from ARB’s traditional incentive programs 

due to regulatory requirements, coupled with the high demand for grant funds in 

general, call for the ARB to evaluate new approaches to providing financial assistance 

to regulated fleets. One concept for a flexible financing option within the ARB’s loan 

program is a combined grant and loan. In this conceptual grant/loan program 

component, the applicant would apply for an incentive grant for a vehicle purchase 

through its local air district’s or local agency’s solicitation process. Upon receiving the 

grant award, the applicant would then apply for a loan through a participating lender in 

CalCAP. Staff will continue to pursue a mechanism to combine these programs in the 

future. 

a) Summary of How State Financial Assistance Can Help 

This section describes how available state financial assistance can be combined and 

integrated to assist fleet operators in meeting the requirements of the proposed 

regulation. The examples used below assume a new day cab, heavy-duty 3-axle truck 

that costs about $115,000. 
-241- 

Absent any State funding through a grant program to provide down payment assistance, 

a vehicle owner may see interest rates on qualifying bank loans in the range of 12 

percent to 15 percent, on average, with terms that may run between 5 and 7 years. 

These monthly payments would average about $2,300 per month, ranging from $2,000 

to over $2,700 per month. Under the current economic climate, many qualifying 

owner/operators may not have the same access to financing as they did in a more 

favorable economy. Similar lending trends are occurring in other financing 

establishments (e.g., OEM financing sectors, dealership financing, etc.) as well. 

Grants from either Prop. 1B Program or the Carl Moyer Program as the sole financial 

assistance source will provide significant relief to the vehicle owner. As an example, an 

award of $50,000 from the Proposition 1B program for a new 2010 model year truck 

would provide a down payment that may qualify the vehicle owner for a bank loan with 

interest rates and terms similar to those referenced above. However, the loan balance 

would be less due to the grant as down payment assistance. The resulting schedule of 

payments may equate to approximately $1,300 per month, ranging from about $1,150 to 

$1,550 per month. 

Qualifying owners may also receive grants through the Carl Moyer Program’s Fleet 

Modernization Program. Depending on local requirements, grant awards may be as 

high as $75,000 for a new 2010 model year truck, with payments of less than $800 per 

month. 

Additional financial assistance through State loan guarantee programs provides added 

“bankability” for the profiled owner/operator. By reducing the risk of default by covering 

a percentage of the principle of the loan and other fees, banks may provide more 

competitive loans at rates that may range from 8 percent to 10 percent. Terms of the 

loan may also be extended from the traditional 5-7 year schedule to a 10 year schedule. 

Such terms are directly tied to the vehicle owner’s economic profile. Combining a grant 

from one of the State’s existing programs, combined with the ARB’s loan program, will 

not only enhance the profiled vehicle owner’s “bankability,” but may also significantly 

provide a more favorable financing schedule. 

C. Federal Funding Sources 

1. U.S. EPA: EPA's National Clean Diesel Campaign 

Under the Energy Policy Act of 2005, the Diesel Emissions Reduction Act (DERA) 

authorized $200 million per year for 5 years for implementation of diesel emissions 

reduction projects across the US. U.S. EPA’s National Clean Diesel Campaign Program 

(NCDC) consists of the NCDC Grants and Funding Program and the State Clean Diesel 

Grant Program with the first appropriation of $49.2 million authorized by Congress in 

2007. The programs provide technical assistance and grants to assist eligible partners 

to adopt diesel emissions reduction strategies. Grant opportunities are announced at 

the national level or via regional agreements such as Region 9 and 10 via the West 

Coast Collaborative. 
-242- 

2. Congestion Mitigation and Air Quality Improvement Program 

The Congestion Mitigation and Air Quality Improvement (CMAQ) program, jointly 

administered by the Federal Highway Administration and the Federal Transit 

Administration, was reauthorized in 2005 under the Safe, Accountable, Flexible, and 

Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). The SAFETEALU CMAQ is designed to bolster efforts to reach National Ambient Air Quality Standards 

This program strengthens the transportation planning and air quality connection and is 

administered via local and state government. Preference is given to cost-effective 

emissions reductions measures, such as diesel engine retrofits, as well as other costeffective emission reduction strategies and congestion reducing projects. 

D. Local Agency Programs 

Most federal and state programs are administered by local air districts. These incentive 

programs include the Carl Moyer Program and state funds appropriated by legislation 

for CMAQ and others. Local agency programs usually focus on projects operating 

within the local air district boundaries. Most programs allow districts to determine the 

types of projects they may fund. Funding may be allocated for stationary, marine, offroad or on-road projects. 

In addition, certain vehicle types and uses of vehicles may have their own specially 

funded programs. The Ports of Long Beach and the City of Los Angeles fund the 

Gateway Cities Clean Air Action Program fleet modernization plan via a combination of 

use fees (concession and container), Proposition 1B, and other matching sources. This 

program, operates in conjunction with the San Pedro Bay Ports Clean Air Action Plan 

and Local Area Council of Governments, and anticipates replacing 16,000 trucks to 

newer used trucks over the next five years. Other agencies and jurisdictions may also 

have settlement and mitigation funds available for air quality improvement programs. 

1. AB 923 Funds 

In 2004, state law was enacted that allows local air districts to collect an additional $2 

motor vehicle registration surcharge ($2 MV Fee), to be used to fund projects under four 

different clean air programs which include the vehicles and equipment under the Carl 

Moyer Program and school bus replacements under the LESB Program. Not all air 

districts are allowed to collect the initial DMV registration fee, while some air districts 

choose not to access the fee. Currently about $50 million per year through 2015 is 

available to pay for projects that are in advance of, or go beyond regulatory 

requirements. 

As described above, funding opportunities for projects under the Carl Moyer Program 

would be limited. However, under the LESB Program, local air districts that chose to 

use AB 923 funds to pay for projects may pay for the replacement of any pre-1987 

model year school bus or 1987 and newer model year bus powered by two-stroke 

engines. 
-243- 

2. AB 2766 Funds 

In 1990 and 1991, the California Legislature enacted legislation – AB 2766 (Sher, 1990) 

and AB 434 (Sher, 1991) – to ensure that California’s air districts and other local 

government agencies have the funding needed to carry out their responsibilities for 

implementing the California Clean Air Act (CAA). The legislation allowed air districts to 

adopt a surcharge of up to $4 on motor vehicle registration fees to be used “solely to 

reduce air pollution from motor vehicles and for related planning, monitoring, 

enforcement, and technical studies necessary for the implementation of the California 

CAA of 1988.” Most air districts in California have adopted a motor vehicle surcharge 

that generates roughly $110 million per year statewide. In accordance with ARB 

guidance, most air districts use at least 50 percent of these funds for emission reduction 

projects such as transportation control measures and clean vehicle projects. Unlike 

some of the other available funding sources mentioned above, AB 2766 and AB 434 

motor vehicle fees are not required to fund projects which are surplus to regulatory 

requirements. 

3. AB 2522 

Assembly Bill 2522, signed into State law on September 30, 2008, authorizes the San 

Joaquin Valley Air Pollution Control District to increase motor vehicle fees - now at $6 

per vehicle - to as much as $30 per vehicle. The additional fees would to be used to 

fund incentive-based programs to achieve surplus emission reductions to remediate 

emissions from mobile sources that the District determines are needed to help achieve 

and maintain ambient air quality standards. If the District opts to collect the full $30 fee, 

it could generate about $75 million in new revenue per year. Of those funds, at least 

$10 million are to be used to mitigate air pollution in disproportionately-impacted 

environmental justice communities. Assembly Bill 2522 authorizes the fees to be 

collected until 2013. Fee authority is extended to 2024 if the U. S. Environmental 

Protection Agency approves the reclassification of the District’s ozone nonattainment 

status to “extreme.” 
-244- 
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XVI. RATIONALE FOR REGULATORY PROVISIONS AND CHANGES TO OTHER REGULATIONS

This chapter describes staff’s rationale for some of the proposed provisions of the 

proposed regulation, as well as the proposed changes to the other existing regulations. 

A. Low Use Exemption 

A vehicle that is operated less than 1,000 miles and less than 100 hours per year in 

California would be exempt from any performance requirements. This allows fleet 

owners to operate some older vehicles if necessary as back up, while not having a 

significant impact on emissions. This provision also provides flexibility for fleets 

operating near the borders of California so that out-of-state fleets would have the ability 

to bring vehicle into California for very brief visits (while not accruing many miles) and 

be exempt from the performance requirements of the regulation. 

In addition, because out-of-state fleets may not be able to predict which vehicles will 

need to come to California incidentally, staff has also proposed to allow an out-of-state 

fleet the option, available only to be used once each year, to operate a single vehicle in 

California for a 3 day period regardless of miles travelled. The fleet owner would be 

required to report the vehicle information immediately before the trip, but would not have 

any additional record keeping requirements to meet. With this, an out-of-state fleet 

would not need to anticipate which vehicles would come to California at the beginning of 

each year. However, as previously stated, a fleet could only use this option once per 

year, and only for one vehicle. 

During the regulatory process, it was suggested that this threshold be raised to allow for 

the accrual of additional miles while avoiding the performance requirements. Staff 

evaluated the emission impacts of raising the 1,000 mile threshold to a higher level, and 

concluded that raising the mileage threshold would result in the current proposal not 

meeting the SIP commitments. 

B. Fleet Average and BACT Percent Limits 

The fleet averaging option provides the most flexibility for fleets to determine the most 

cost effective action to take. The fleet average option allows fleets to select which 

vehicles to upgrade or retire rather than having to follow a prescribed schedule. It 

provides more flexibility to buy used vehicles to comply with the proposed regulation, 

lowering compliance costs. It also provides a mechanism for fleets to take advantage of 

NOx control technologies that, while not achieving the maximum NOx emissions 

reductions, would nonetheless lower fleet emissions and delay vehicle replacements. 

The fleet average also provides a mechanism to provide credit for the use of alternative 

fueled vehicles or hybrids. 

The BACT percent limits is best suited for fleets that prefer to buy engines with 2010 

emissions technology. It allows fleets to replace a vehicle a single time during the 

compliance period. It is fairly straightforward to understand and to plan for future 

replacements. It also is the best option for fleets to use if they need to keep some older 

equipment. For example a fleet that has a specialized 1991 model year crane and 9 
-246- 

vehicles may use this option by installing a verified DECS on the crane and keeping it 

through 2022 provided that the other vehicles are being replaced to meet the fleet 

percentage requirements. 

C. Delays to the NOx Performance Requirements 

1. Vehicles below Specific Mileage Thresholds 

Staff has proposed to delay compliance with the NOx performance requirements, while 

maintaining the PM performance requirements, for vehicles operated below specific 

mileage thresholds. The proposed mileage thresholds are 7,500 miles per year for 

tractors and vehicles with a GVWR greater than 33,000 pounds, and 5,000 miles per 

year for all other vehicles with a GVWR less than 33,000 pounds. These thresholds 

were proposed based on staff’s cost effectiveness evaluation for achieving PM and NOx 

reductions on individual vehicles, and on the number of vehicles that would potentially 

qualify for the delay. 

First, staff concluded that it was appropriate to establish different thresholds (based on 

vehicle weight) for medium heavy -duty vehicles and heavy heavy-duty vehicles and 

tractors. This is because, on average, tractors and vehicles greater than 33,000 pounds 

are more expensive to replace than smaller vehicles. In addition, larger vehicles tend to 

drive more miles each year than smaller vehicles. Also, the proposed thresholds 

generally coincide with thresholds established by the United States Internal Revenue 

Service regarding tax suspensions, for which fleets with such vehicles may file. This tax 

suspension applies to highway motor vehicles having taxable gross weights of 55,000 

pounds or more that are operated on public highways annually for 7,500 miles or less 

for agricultural vehicles, or 5,000 miles or less for other businesses. 

As part of the analysis, staff evaluated the emissions impacts associated with this 

proposed provision. Using the statewide vehicle population in the emission inventory, 

vehicles operated below these mileage thresholds represent about 15 percent of the 

total vehicle population of in-state vehicles, and about one percent of the total vehicle 

miles traveled. This represents about a two percent loss in potential total NOx and PM 

emission benefits. 

The following example compares the PM and NOx emissions in 2014 of a vehicle 

qualifying for this provision relative to a vehicle in a fleet that is meeting NOx and PM 

performance requirements. In its analysis, staff used a vehicle with a 1990 model year 

engine traveling 5,000 miles per year and compared it to an average vehicle in a fleet 

that met the 2014 fleet average and traveled 30,000 miles annually. The results of this 

comparison are shown below in Table XVI-1. 
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Table XVI-1: Emissions Comparison of Low Mileage Vehicle and Typical Fleet 

in 2014 

Fleet Comparison 

Annual Miles 

Traveled NOx (lbs) PM (lbs) 

Typical Vehicle in a Fleet Meeting 

2014 Fleet Average 30,000 650 7 

1990 Model Year Engine with 

verified DECS 5,000 240 6 

As can be seen, the heavy-duty vehicle with a 1990 model year engine and a DPF that 

travelled 5,000 miles per year would emit about 240 pounds of NOx per year, and about 

6 pounds of PM. A heavy-duty vehicle travelling 30,000 miles in a fleet complying with 

the proposed regulation in 2014 would emit about 650 pounds NOx and about 7 pounds 

of PM. Without a verified DECS, the 1990 model year vehicle would emit about 37 

pounds of PM annually. Based on this analysis, staff believes that providing a delay in 

the NOx performance requirements for vehicles that travel below the specific mileage 

thresholds described above would provide fleets with additional flexibility and reduced 

costs without sacrificing significant emission benefits. 

It was suggested by some stakeholders that fleets would simply increase the number of 

vehicles that they have so that they may stay below these mileage thresholds. Staff has 

considered this, but does not believe that such a situation is likely to occur. Because 

fleets utilizing these provisions still must still install a verified DECS on their vehicle, and 

because the cost of such a retrofit relative to the value of the vehicle on which it would 

be installed is often greater, staff does not believe it makes economic sense for fleets to 

pursue such actions. In fact, staff expects that many fleets will retire some of their 

older, less critical, lower use vehicles to avoid the cost of verified DECS, and instead 

better utilize the remaining vehicles that they have, or will rely on subcontractors or 

rentals where possible. 

Staff also evaluated alternative thresholds and requirements and concluded that the 

current proposal provides sufficient reductions to California’s SIP commitments and an 

incremental increase would result in not meeting the SIP commitment. As shown in 

Table XVI-2 a change to the current proposal would increase emissions in key years. 

The left column shows the emissions increase from permanently exempting all vehicles 

below the current mileage thresholds from the PM and NOx performance requirements. 

The middle column represents raising the mileage thresholds to 10,000 miles for all 

vehicles until 2021; they would still be required to install verified DECS. Finally, the 

right column shows the impact of permanently exempting all vehicles operating below 

10,000 miles from the NOx and PM performance requirements. 
-248- 

Table XVI-2: Alternatives Emission Loss Compared to Staff Proposal (tpd) 

Permanently 

Exempt from PM 

and NOx at 

Current Mileage 

Threshold 

NOx Exempt 

up to 10,000 

Miles until 

2021 

Permanently 

Exempt Up to 

10,000 Miles Calendar 

Year 

NOx PM NOx PM NOx PM 

2014 0.0 0.3 5.2 0.0 5.2 0.7 

2017 0.0 0.3 3.6 0.0 3.6 0.6 

2020 0.0 0.2 3.0 0.0 3.0 0.4 

2023 3.2 0.2 0.0 0.0 5.9 0.3 

2. NOx Exempt Areas 

Staff recognizes that air quality problems are less severe in some parts of California. 

For that reason, staff proposed a special provision for vehicles operating exclusively in 

counties that are in attainment of the federal ozone and PM ambient air quality 

standards, and do not contribute to downwind exceedances of the state or federal 

ozone and PM standards. The provision would allow vehicles that operate exclusively 

in “NOx exempt areas” to be delay compliance with the NOx performance requirements 

until January 1, 2021. However, these vehicles would still remain subject to PM 

performance requirements. This is because diesel PM emission reductions are still 

necessary to reduce the localized risk of PM exposure, and such an approach is 

consistent with similar provisions provided in the In-Use Off-Road Diesel Vehicle 

Regulation. 

3. Agricultural Vehicle Provisions 

The agricultural vehicle provisions would exempt lower use agricultural vehicles from 

the NOx and PM performance requirements for a specified period of time. Agricultural 

vehicles are those that are used exclusively in field operations, those that transport 

agricultural products to the first point of processing after harvest, and certain trucks 

owned by chemical supply companies that deliver chemicals or crop protection products 

from a distribution center to a farm. Under these provisions, agricultural vehicles 

operating above the mileage thresholds (with the exception of specialty agricultural 

vehicles) would be required to comply with the NOx and PM performance requirements 

just as any other vehicle. 

In considering these provisions, staff ensured that two key parameters were met. First, 

that the provisions would not jeopardize the anticipated emission benefits of the 

proposed regulation such that the State did not meets its SIP commitments, in any year, 

in the San Joaquin Valley and the South Coast Air Basins; and second, that the 

provisions did not result in any adverse impacts relative to localized risk. While the 

proposed agricultural vehicle provisions meet the first parameter, in that the State meets 

or exceeds its SIP commitments in all years evaluated despite a small loss in emission 
-249- 

benefits as a result of the proposed provisions, additional work is needed to more fully 

understand the scope of any localized risk impacts from the delay in the PM 

performance standards for these vehicles, and to develop recommendations to address 

the impact. 

a) Compliance with the State’s SIP Commitments 

Staff estimates there are about 22,000 agricultural vehicles within the scope of the 

proposed regulation operating in California, which service over 72,000 farms and other 

agricultural operations through out the state. Agricultural vehicles are most prevalent in 

the San Joaquin Valley (about half of the statewide population), with the rest operating 

in other areas of the state (in contrast, there are very few agricultural vehicles operating 

in the South Coast Air Basin). Information about the statewide population of agricultural 

vehicles was obtained from a number of sources, including survey data and vehicle 

registration data from the DMV. In general, and consistent with statewide fleet as a 

whole, most agricultural vehicle owners have fairly small fleets. Some reported fleets 

larger than 10 vehicles, and only a few reported owning more than 20 vehicles. 

Based on the information available, about 70 percent of the agricultural vehicles in the 

state are expected to be limited-use agricultural vehicles (operate less than specific 

mileage thresholds based on the model year of the engine), and 50 percent are 

expected to be low-use agricultural vehicles (those which operate less than 10,000 

miles per year). Using this and other information, staff estimates that a delay in the 

NOx and PM performance standards for these vehicles will result in a loss of about 1 

TPD of SIP NOx reductions in the San Joaquin Valley in 2017. However, despite this, 

staff estimates that the proposed regulation will still provide 49 TPD of SIP NOx 

reductions in 2017 in the San Joaquin Valley, matching the State’s SIP commitment for 

this region. 

To better ensure that the SIP commitment is met, the proposed regulation would limit 

the number of limited use and low-use agricultural vehicles that could take advantage of 

the proposed delay in the NOx and PM performance standards. This is achieved by 

fleets “locking in” the number of limited use and low-use agricultural vehicles in 2010, 

based on their 2009 fleet. Once locked in, the number of these vehicles cannot 

increase over the entire compliance period. In addition, the limited use agricultural 

vehicle population reported in 2010 must meet the PM and NOx performance standards 

by January 1, 2017, and the low-use agricultural vehicles that operate above 1,000 

miles must meet the NOx and PM performance standards by January 1, 2023. In 

addition, while the proposed regulation would allow agricultural fleets to replace limited 

use and low-use vehicles under certain conditions, these vehicles must be replaced with 

newer vehicles, a natural decrease in emissions from these vehicles over time, until 

they must meet the NOx and PM performance standards. 

b) Definition of Agricultural Vehicle 

A number of different types of vehicles are included in the definition of agricultural 

vehicle, and typically include one of four types: 
-250- 

• vehicles that are used on a farm; 

• vehicles that deliver products from a farm to a point of first processing; 

• specialty agricultural vehicles, and; 

• specialized vehicles that deliver specialty chemicals (fertilizers and crop protection 

products) to a farm. 

The first three types of vehicles are used in the active production, cultivation, and 

harvesting, and transportation of crops, and for other agricultural operations. These 

vehicles are typically owned by a farmer, a farmer cooperative, or a custom harvester or 

hauler (a for-hire operator to perform such services for farmers, typically under a 

contract). As such, staff believes it is appropriate to include such vehicles in the 

proposed definition. 

Staff also proposed to include vehicles that exclusively deliver fertilizer or crop 

protection chemicals to a farm. These vehicles are typically specialized, and are 

required by the United States Department of Transportation to have certain placards. In 

addition, these vehicles are predominantly owned by farm supply companies, and these 

companies must have a license through the California Department of Pesticide 

Regulation and/or the California Department of Food and Agriculture. Staff’s rationale 

for including such vehicles is that these vehicles typically operate on a regional basis, 

usually within a 50 mile radius of a chemical distribution center. Vehicles in this service 

are important in the distribution of these chemical products in the agricultural industry, 

as they are often dispatched on short notice to deliver various chemicals or gases to a 

farm while the weather conditions are favorable for their application. It is important to 

note that vehicles that deliver any other products or equipment to the farm such as feed, 

seed, fuel, cryogenic liquids, parts or other items, would not be included in the this 

definition. 

Specialty agricultural vehicles include a subset of agricultural vehicles including: 

• nurse rigs; 

• cotton module trucks; 

• feed trucks used by cattle and calf feed lots, and; 

• water trucks owned and operated by farmers for dust control and irrigation. 

Staff included such vehicles in the definition of agricultural vehicles for a number of 

reasons, including the specialized nature of these vehicles and their high replacement 

costs, the seasonal nature of their use, their relatively low annual mileage, and their 

use predominantly on a farm. However, because there is no mileage limitation on 

these vehicles, and to ensure that the State meets its SIP commitments in 2017, 

especially in the San Joaquin Valley, staff is proposing to cap the number of these 

vehicles that may claim the specialty vehicle provisions in any given year. This cap 

would be no more than 1,100 vehicles in the San Joaquin Air District, and no more than 

2,200 statewide trucks. Table XVI-3 shows the estimated number of specialty vehicles, 

by body type, operating in the state. 
-251- 

Table XVI-3: Specialty Agricultural Vehicle Population Estimates 

Estimated Number of Vehicles 

(2008) 

Body Type San Joaquin Valley Statewide 

Cotton module 170 193 

Water 622 1,022 

Feed Trucks (Cattle and Calf Feed Lots) 10 100 

Nurse Rig 94 190 

Total 896 1,505 

c) Localized Risk Impacts 

While staff believes that the proposed amendments will meet the state’s PM and NOx 

emission reduction commitments under the SIP, there is still a need to ensure that any 

delay in the PM performance standards does not have an adverse impact on the 

anticipated reduction in exposure risk to diesel PM. To evaluate the potential impacts 

on risk from staff’s proposed agricultural vehicle provisions, staff performed a health risk 

assessment of two “generic” agricultural processing facilities that might receive vehicles 

that do not meet the PM performance standards of the proposed regulation. 

For its analysis, staff modeled two generic facilities, one in the Bakersfield area, and 

one in the city of Commerce. In its analysis, staff assumed only vehicles that do not 

meet the PM performance standards (i.e., do not have DPFs) visited the facility. As 

such, to the extent that vehicles that do meet the PM performance standards visit these 

facilities, the estimated risk impacts are conservative. In other words, the potential risk 

impact of staff’s proposal depends not on the total number of trucks that visit a facility, 

but rather on the number of trucks that visit a facility and do not have PM controls 

installed. In addition, actual risk levels will vary due to site specific parameters, 

including the number of uncontrolled trucks and associated emission rates, operating 

schedules, routes traveled to the location, site configuration, site meteorology, and 

distance to receptors. 

To investigate the potential risks associated with low-use and limited use agricultural 

vehicles used to transport agricultural commodities from the field to a processing facility, 

ARB staff developed general assumptions bracketing a range of possible operating 

scenarios and estimated potential cancer risks. Using this approach, cancer risk was 

estimated as a function of the number of “uncontrolled” truck trips and the distance from 

the roadway or processing facility. A description of staff’s assessment is provided in 

Appendix E. Since the activity at any given processing facility can vary based on its 

throughput, staff’s analysis provides an initial assessment of potential impacts of staff’s 

proposal. However, unless an actual facility is modeled, using data specific to that 

facility, the actual risk from staff’s proposal cannot be determined. 

Table XVI-4 below provides the results of staff’s analysis for Bakersfield and shows the 

distances from the facility or roadway boundary wherein the risk is above 10 in a million 
-252- 

for different uncontrolled agricultural vehicle volumes. For example, a facility that has 

28,800 roundtrip truck trips per year, the risk level of 10 in a million could extend to a 

downwind distance of about 1,100 feet from the facility or roadway boundary. 

Table XVI-4: Distances from the Facility Boundary wherein the Risk is 10 in a 

Million for Different Agricultural Vehicle Volumes 

Vehicles/Yr Distance 

(Meters) 

Distance 

(Feet) 

5,760 N/A N/A 

11,520 50 164 

17,280 120 394 

23,040 250 820 

28,800 350 1,148 

43,200 600 1,968 

57,600 850 2,789 

72,000 1,000 3,281 

86,400 1,300 4,265 

115,200 1,700 5,577 

144,000 1,900 6,234 

Because of the uncertainty with staff’s analysis, it is unclear as to the actual impact of 

staff’s proposal on sensitive receptors near agricultural processing facilities. While 

many of these facilities are located in rural areas, away from population centers, not all 

of them are. In addition, even for those that are located in rural areas, it is necessary in 

some instances for these vehicles to travel through more urban areas. Finally, while 

staff’s analysis looked at individual facilities, it was not able to understand the 

cumulative impact of several facilities located in close proximity to one another. While 

staff does not believe that these findings are sufficient to delay staff’s proposal for lowuse and limited use agricultural vehicles, staff believes it is necessary to better 

understand this potential impact by evaluating several actual facilities throughout the 

state. Staff intends to continue their evaluation of the potential risk impacts of this 

proposal over the next 12 to 18 months, and, if appropriate, develop recommendations 

to ensure that the proposal does not result in an unacceptable impact on risk to 

communities. 

4. Unique Vehicles 

While the regulation was written to allow the purchase of used vehicles to lower the 

overall costs of the proposed regulation, staff recognizes that certain types of vehicles 

that perform special functions are less common and that used a vehicle may not exist. 

In the event that such a vehicle needed to be replaced, there may not be a used 

replacement available, and the fleet owner would be forced to purchase a new 

replacement vehicle. To alleviate such a situation, staff is proposing to delay the 

compliance with the NOx performance requirements of such vehicles until 

January 1, 2021. In receiving such flexibility, the fleet owner would have to take action 

to ensure that all other vehicles in that fleet meet the NOx and PM performance 
-253- 

standards. In other words, the unique vehicle would need to be included in the fleet for 

determining the fleet average or the BACT percentages, and all other vehicles would 

still have to be cleaned up first. However, once all other vehicles in the fleet meet the 

BACT criteria, the remaining unique vehicle would need to take actions to meet the 

specific criteria in the proposed regulation. 

D. Cab Over Engine Tractors with 57 foot Trailers 

In California, the overall length of a truck and semi-trailer combination can be no more 

than 65 feet. However, a semi-trailer as long as 57 feet can be pulled provided the 

truck-tractor is a short cab over-engine type tractor. A 57 foot trailer cannot legally be 

pulled by a tractor with a conventional configuration. However, production of new cab 

over-engine type tractors in North America ceased in 2007, using 2006 model year 

engines. As such, no new cab over engine type tractors having 2007 model year 

engines are available, and none are expected to be made in the future. 

To address this, staff is proposing a provision to delay the NOx performance 

requirements for cab over-engine type tractors exclusively pulling 57 foot trailers until 

January 1, 2018. Businesses that typically use such configurations include those that 

haul products that have a low density such as empty cans, bottles, or pallets. 

Unless high efficiency verified NOx and PM DECS become available, the proposed 

regulation would impose a significant cost for businesses using these vehicles and 57 

foot trailers because the regulation would effectively require the replacement of both the 

tractor and the trailer. This is because operators using cab over engine type tractor 

would have to switch to using conventional cab truck-tractors pulling 53 foot trailers in 

order to stay within California’s length laws. The 4 foot difference between the two 

trailers amounts to about 7 percent less cargo that can be carried. As a result, these 

companies will experience an annual economic loss because the shorter trailer will 

carry less cargo. More truck trips would be required to deliver the same amount of 

product. More trips would result in using more fuel and in higher fuel expense. 

Similarly, additional trips would result in more operating expenses such as increase 

wages paid by the business. 

E. Small Fleet Provisions 

Staff is proposing to delay the NOx and PM performance requirements for fleets of three 

or fewer vehicles until January 1, 2013. According to 2006 DMV data, as shown in 

Figure XVI-1, almost 50 percent of fleets have three or fewer diesel vehicles subject to 

the proposed regulation. Also, small fleets tend to operate older vehicles relative to 

larger fleets, but would not benefit from the flexibility provided by the fleet average 

option or the BACT percent limit option because of the limited number of vehicles. 
-254- 

Figure XVI-1: Number of Vehicles by Fleet Size (California Department of 

Motor Vehicles, 2006) 

1 Truck

32%

2 Trucks

10%

3 Trucks

6% 4 Trucks

4%

21 ~ 50 Trucks

8%

51 ~ 100 Trucks

4%

> 100 Trucks

16%

6 ~ 10 Trucks

9% 5 Trucks

3%

1 1 ~ 20 Trucks

8%

Because of the economic challenges facing small fleet operators, staff believes it is 

appropriate to provide additional time for compliance, and to establish somewhat lesser 

regulatory requirements for small fleet operators during the first years of the program. 

However, while additional time is provided, these vehicles will still ultimately need to 

meet the same NOx and PM performance standards as a vehicle owned by a larger 

fleet operator. As such, staff believes that the proposed small fleet provisions will 

reduce the initial costs to small fleets to comply with the proposed regulation in the near 

term, but will still provide substantial emission reductions from these vehicles in the long 

run. 

F. Credit for Hybrid and Alternative Fuel Vehicles 

Staff is proposing credit for the use of hybrid vehicles to accelerate the introduction of 

hybrid technology in heavy-duty vehicles. Hybrid technology can play an important role 

in meeting California’s goals of reducing GHG emission under AB32. 

While hybrid diesel vehicles production today is low, due to increasing fuel prices and 

the growing maturity of the hybrid technology, the wide spread use and availability of 

hybrid vehicles in the future is anticipated. At this point in time, staff believes it is 

appropriate to establish provisions in the proposed regulation that will encourage the 

purchase and use of medium heavy-duty and heavy heavy-duty hybrid vehicles. While 

the benefit of hybrid technology to reduce GHG emissions is clear, it also has the 

potential to provide criteria pollutant emission reductions as well. 

Many truck and system makers are currently developing heavy-duty hybrid prototypes 

or pre-production units, an important point in the evolution of hybrid technology, but 

these efforts have not yet achieved critical mass. One of the key barriers to the early 

success of hybrid vehicles is that production volumes are low, so prices remain high. 
-255- 

The hybrid credit staff is proposing to include in the regulation would be provided for a 

hybrid vehicle as long as the fuel economy of the hybrid is at least 20 percent better 

than an equivalent, conventionally fueled vehicle. A number of hybrid platforms have 

already achieved this level of incremental efficiency improvement, and staff does not 

believe that it will present a barrier for receiving credit. Staff has also proposed that the 

credit would expire January 1, 2018. By that time staff believes hybrids will be much 

more common and will likely be more cost-effective to operate than conventional 

vehicles, eliminating the need top provide further credits. 

G. Enforceability Provisions 

1. Requirements for Possession of Valid Operating Permit 

Staff is proposing that in order for fleets to take advantage of any of the flexibility 

provisions or compliance extensions of the proposed regulation, including the fleet 

average, BACT percent limits, small fleet, etc, that the fleet operator possess and 

provide one of the following valid operating permits: 

• a valid California motor carrier of property number, 

• a valid identification number assigned by the United States Secretary of the 

Department of Transportation, or 

• a valid operating authority number issued by the Public Utilities Commission, or 

• other applicable valid operating authority number approved by the Executive Officer. 

This requirement was included at the suggestion of stakeholders to ensure that fleets 

that are utilizing the flexibility provided by the regulation are also complying with 

applicable operating permit requirements to lawfully travel on California highways. Staff 

believes that such a requirement will improve the overall enforceability of the regulation. 

2. Requirements for Brokers, Motor Carriers and Other Vehicle 

Dispatchers 

In an effort to ensure that all vehicle owners comply with the proposed regulation, instate or out-of-state motor carriers, California-based brokers, or California residents that 

operate or direct the operation of any vehicle subject to the proposed regulation would 

be responsible for hiring fleets with compliant trucks. Both motor carriers and brokers 

direct the operation of their drivers, and as such, are in a unique position to verify 

compliance with the proposed regulation. Such a requirement is already in place for 

other aspects of motor vehicle compliance, such as requiring proof of vehicle insurance, 

proper drivers licensing, and proof of compliance with various drug testing, vehicle 

safety, and worker compensation requirements. 

The proposed regulation would require these motor carriers and brokers to retain 

records documenting that the drivers they hire or dispatch are in compliance with the 

proposed regulation, but would have an affirmative defense for violations by a vehicle 

operator they dispatched if they can demonstrate that they verified the compliance 

status of the operator at the time they were hired or dispatched. 
-256- 

To assist these motor carriers and brokers, the proposed regulation includes the 

development of a system to allow them to easily determine the compliance status of any 

business or vehicle operator. Under such a system, vehicle owners would electronically 

report to ARB the information regarding their vehicles and their compliance 

mechanism. Upon completion, an Internet based system would generate a Certification 

of Reported Compliance that would be available for printing and would be available online. The system would allow motor carriers and brokers to determine which of their 

drivers have reported compliance with the proposed regulation to ARB. 

H. Exclusion of Personal Use Motor Homes 

Staff has proposed to exempt non-commercial motor homes from the scope of the 

proposed regulation for a number of reasons. First, owners of these vehicles do not 

have the ability to offset the compliance costs since personal use motor homes do not 

generate income nor appreciate in value. In addition, these vehicles typically operate 

very few miles in California, and as such, do not contribute significantly towards 

emissions relative to other vehicles covered by the proposed regulation. 

According to 2007 California Emission Forecasting System (CEFS) estimation, the 

annual average PM and NOx emissions from diesel-powered motor homes for the years 

between 2007 and 2020 are less than 0.3 percent and 0.5 percent, respectively, of the 

overall mobile fleet emission respectively (ARB, 2007a). The EMFAC2007 estimates 

that the annual mileage driven per motor home in calendar year 2010 is approximately 

3,000 miles within the state (ARB, 2007b). Since the average mileage is low, it would 

indicate that most private use motor homes are not driven a significant number of miles 

within the state, are used infrequently, or are parked for a significant amount of the time. 

Considering the potential financial burden on owners of personal use motor homes, and 

the fact that most personal use motor homes would qualify for the proposed delay of the 

NOx performance requirements based on their mileage, staff believes that excluding 

personal use motor homes from the proposed truck and bus regulation is appropriate. 

I. Safety Considerations 

Through the course of the development of the proposed regulation, staff considered 

potential concerns raised by affected stakeholders regarding safety from the operation 

of vehicles that had been retrofit with verified DECS. These issues included: 

requirements for diesel retrofits on agricultural and fuel delivery vehicles could lead to 

fires, increased engine operating temperatures due to backpressure, and potential 

visibility restrictions. While many of these concerns are unfounded, staff believes it is 

appropriate to include provisions in the proposed regulation which could address any 

safety concerns regarding the use of verified DECS under the regulation. Such an 

approach was also included in the In-Use Off-Road Diesel Vehicle Regulation for the 

same purpose. 
-257- 

A safety issue was also raised regarding the use of SCR systems, and the use of 

ammonia or urea as reducing agents. While ammonia is significantly more hazardous 

than urea, its use as a reductant in SCR systems for diesel vehicles is limited, with no 

major engine or DECS manufacturers proposing its use. The preferred reductant is 

urea, which has limited health effects in that it can cause skin or eye irritation if these 

parts of the body are exposed. 

It is not the intent of the proposed regulation to require the unsafe installations of any 

verified DECS. In fact, the proposed regulation only requires retrofits if they are verified 

as proven, effective, durable, safe, and warrantied; it never requires retrofits if they are 

not verified, will not work, or are unsafe. To address this, the proposed regulation 

provides a process under which the Executive Officer could determine that if a verified 

DECS cannot be installed safely, its use is not required. We believe the safety 

provisions in the verification procedure and the proposed regulation are adequate to 

ensure that the regulation will not require any unsafe installations. The proposed 

regulation also contains an appeals procedure so that if a fleet owner disagrees with the 

Executive Officer’s decision regarding the safety of a device, the fleet owner has the 

opportunity to challenge an Executive Officer’s determination that a retrofit device does 

not impair the safe operation of a vehicle. 

J. School Buses 

Currently there are about 24,000 school buses that transport children to and from 

school in California each year. School buses tend to accrue fewer miles than many 

other heavy-duty vehicles operating in California, which leads to vehicles having a long 

useful life. As such, school bus fleets tend to be comprised of buses that have been or 

will operate for 30 years or more. Additionally, school buses are also predominately 

operated by local school districts which are dependent on limited public funds. Since 

replacing these vehicles is costly, school districts are likely not able to comply with the 

NOx performance requirement due to limited school district budgets. 

However, reducing diesel PM emissions is critical due to reducing the health risks 

associated with exposure to diesel PM, especially for children. School age children are 

especially vulnerable to the affects of air pollution. 

As such, staff is proposing that each school bus fleet or school bus sub-fleet (dieselfueled vehicles that will be incorporated as part of the school bus fleet) must comply 

with PM (but not the NOx) performance requirements of the proposed regulation that 

are specific for school buses. Under this schedule, by January 1, 2014, all diesel fueled 

school buses must be retrofitted with the highest level verified diesel emission control 

strategy available to be used on any engine used in school buses regardless of the 

compliance option chosen. However, school bus fleets or school bus sub-fleets do not 

need to meet the NOx performance requirements of the proposed regulation. 

In addition, any school bus manufactured before April 1, 1977, must be taken out of 

service no later than January 1, 2012. This is because these vehicles were 
-258- 

manufactured before minimum federal safety standards were in place. However, 

incentive funding through Proposition 1B is available to replace these buses. 

Appendix I further discusses the regulatory requirements, available incentive funding, 

and existing technology available for school buses. 

1. Safety Issues 

During the development of the proposed regulation, several school district stakeholders 

expressed concerns about the potential safety impacts of staff’s proposal on school 

children. This concern was expressed in the context that many school districts do not 

have the funding available to meet the proposed PM performance standards for school 

buses, and will likely reduce or eliminate school transportation services instead of 

complying with the proposed requirements. This would in turn mean that many children 

will be either forced to walk to school or ride in a private vehicle, which many studies 

have shown is significantly less safe than transportation via a school bus. 

Staff agrees with these stakeholders on the safety advantage that school buses provide 

relative to other forms of transportation, and it is not the intent of the staff to establish 

requirements that would reduce the health impacts on school children while 

simultaneously reducing the safety of school children. However, as can be seen in 

Figure XVI-2, the number of students transported annually in California has been 

declining statewide since 2002 as school districts across the state have reduced or 

eliminated school transportation services. Staff does not believe that the proposed 

regulation will have an effect on this continuing trend, but will continue to monitor the 

situation. If transportation services are adversely impacted by the proposed regulation, 

staff will consider, as appropriate, alternatives to ensure the safety of school children is 

not jeopardized. 
-259- 

Figure XVI-2: California K-12 Students Transported at Public Expense 

8.6

8.8

9

9.2

9.4

9.6

9.8

10

01/02 02/03 03/04 04/05 05/06

School Year

100,000 Students

Source: Data from School Transportation News Buyer’s Guide as reported by the California 

Department of Education. 

K. Drayage (Port) Trucks 

Drayage trucks are diesel-fueled, heavy-duty trucks that transport containers, bulk, and 

break-bulk goods to and from ports and intermodal rail yards to other locations. Staff 

estimates that about 20,000 drayage trucks regularly service ports and rail yards in 

California. ARB adopted a regulation in December 2007 that requires all vehicles 

entering ports and intermodal rail yards to have PM controls by December 31, 2009, 

except for 2004 to 2006 model year engines. Staff at that time were concerned with 

creating any incompatibility with the then planned proposed regulation because it was 

uncertain what the final proposal would be. 

To ensure consistency between the requirements in the drayage truck regulation and 

the proposed regulation, staff is proposing to require drayage trucks with 2004-2006 

model year engines to install the highest level verified DECS according to the same 

schedule as all other trucks subject to the proposed regulation. This requirement would 

align the drayage truck regulation with the proposed regulation. This would also help 

meet the State’s PM emission reduction commitments, and would ensure uncontrolled 

trucks would not cycle into the drayage fleet to avoid the requirements of the proposed 

regulation. 

Staff is also proposing to include drayage trucks in the scope of the proposed regulation 

beginning January 1, 2021. This would harmonize the requirements between the two 

regulations after that date, and would provide additional emission reductions needed to 

meet the 2023 ozone SIP commitments. 
-260- 

L. Two-Engine Cranes 

Throughout the regulatory development process, staff has been working to address a 

number of issues regarding the control of emissions from two-engine cranes by multiple 

regulations. As discussed in Chapter XI, cranes are currently regulated by as many as 

four different regulations, including the In-Use Off-Road Diesel Vehicle Regulation, the 

Portable Engine and Equipment Regulation, the Cargo Handling Equipment Regulation, 

and the statewide Portable Engine Registration Program. This has created a confusing 

and conflicting regulatory environment. To address this issue, and to provide a path for 

crane operators to clean-up these vehicles in a more cost-effective manner, staff’s 

proposal would place the regulation and clean-up of all two-engine cranes in the In-Use 

Off-Road Diesel Vehicle Regulation. Staff believes that this approach is superior to the 

current approach. This is especially true when considering the unique issues facing 

cranes, including the safety and feasibility of repowering and/or retrofitting upper crane 

engines. 

In evaluating two-engine cranes as part of this regulatory effort, staff identified the 

following areas of concern: 

• Issues with compliance with more than one regulation 

• Feasibility issues with the replacement and/or retrofit of auxiliary engines 

• Safety compliance issues 

• OSHA and Cal-OSHA re-certifications 

• Costs 

Some of these issues are further discussed below. 

1. Feasibility of Repowering and Retrofitting 

Modifications to the original crane design cannot be easily performed. Each 

modification requires specialized engineering to design/specify parts to ensure the safe 

operation of a modified crane. For example, the repower or retrofit of a secondary 

engine can create safety and design concerns, as the secondary engine is part of the 

counterweight system of the crane. A small weight change can have a significant 

impact on a crane’s lifting capacity and interfere with the electronic controls 

programmed into the crane’s positioning system gear (Sierra, 2007). 

Repowering or retrofitting secondary crane engines requires crane manufacturers’ 

approval first, and then requires recertification by OSHA and Cal-OSHA. Therefore any 

modification, alteration or change to a crane that affects its original design, and is not 

authorized and approved by the crane manufacturer, is strictly prohibited and voids any 

manufacturer warranties (Sierra, 2008 and Sierra 2007). This includes changes 

associated with repowering or retrofitting the auxiliary engine. Most two-engine crane 

manufacturers have submitted to staff that physical changes to the crane are 

unauthorized. Copies of these letters are provided in Appendix L. 
-261- 

Without staff’s proposed modifications, many two-engine cranes in California would 

have to be replaced to meet the existing requirements of existing regulations since 

these engines cannot be replaced with newer, cleaner engines. Such a requirement 

would result in significant costs to crane operators, as new two-engine cranes can cost 

as much as several million dollars. 

2. Impact on Emissions 

Staff evaluated the emission impacts of their proposal using information provided by 

crane operators and from DMV data. In their analysis, staff modeled the emission 

benefits from two-engine cranes under existing regulations, and then compared this to 

the anticipated emission benefits of the staff proposal. The results of this analysis for 

NOx are shown in Figure XVI-3. As can be seen, there would be a slight increase in 

NOx emissions in 2010 through 2013 from staff’s proposal, but a considerable NOx 

benefit after 2013. 

Figure XVI-3: NOx Emissions Benefits of Staff Proposal 

0

1

2

3

4

5

6

7

2010201120122013201420152016201720182019202020212022202320242025

NOx (tpd)

Baseline with Existing

Regulations

Proposed Regulation

As shown in Figure XVI-4, the current proposal would result in a small increase in PM 

emissions in 2010, but would result in substantial PM reductions thereafter. 
-262- 

Figure XVI-4: PM Emissions Benefits of Staff Proposal 

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

2010201120122013201420152016201720182019202020212022202320242025

PM (tpd)

Baseline with Existing

Regulations

Proposed Regulation

Because of this analysis, staff believes that this proposal will result in additional 

emission benefits relative to current regulations, and will achieve these reductions at a 

substantial cost savings. More details on the estimates for number of cranes and 

details of the emissions calculations methodology are in Appendix L. 

3. Effect on SOON 

In adding two-engine cranes to the proposed amendments to the In-Use Off-Road 

Diesel Vehicle Regulation, staff is also proposing to exclude the horsepower in twoengine cranes from a fleet’s maximum horsepower in determining eligibility for Surplus 

Off-Road Opt-in for NOx (SOON). This would be consistent with the intent of the 

regulation in that the second engine in two-engine cranes, as well as the propulsion 

engine in on-road two-engine cranes, which were never previously part of the 

regulation, were not considered in determining fleet size and eligibility for the SOON 

program. 

M. Privately-Owned Two-Engine Street Sweepers 

For many of the same reasons as mentioned for the two-engine crane, staff is 

proposing changes for privately-owned with two-engine sweepers. These changes are 

intended to provide a more straightforward regulatory approach, while reducing the 

overall cost of cleaning up these vehicles. 

Based on information provided by the sweeper industry, in many cases it is infeasible to 

repower the auxiliary engines in these vehicles with new engines (which are subject to 

the Portable Engine and Equipment Regulation); the only alternative is to replace the 

entire vehicle with a new vehicle having a certified engine. Staff does not believe it is 

necessary or financially feasible for many fleets to purchase new vehicles simply to 

comply with the requirements of the Portable Engine and Equipment Regulation. 
-263- 

Therefore, staff is proposing to regulate both engines under the proposed regulation. In 

this way, private sweeper operators would still be required to install PM controls on both 

the drive engines and the auxiliary engines in the 2010 to 2013 timeframe under the 

proposed regulation. The results for NOx are shown in Figure XVI-5. There would be a 

small increase in NOx emissions prior to 2012 but there would lower emissions starting 

in 2013. For PM there could be a minimal loss in benefits in 2010 but considerable 

benefits after 2011. With the current staff proposal, all engines would have verified 

DECS by January 2014. The Portable Engine and Equipment Regulation would require 

a phase-in of verified DECS starting in 2013. 

Figure XVI-5: NOx Emissions with Staff Proposal 

To further reduce costs to sweeper fleets, while incentivizing the purchase of newer, 

cleaner private two-engine sweepers, staff is proposing to modify the Public Agency and 

Utility Diesel-Fueled Vehicles Regulation such that municipalities may receive 

retirement credit for the sale of two-engine sweepers having certified 2004 through 2006 

model year engines within California. Currently, municipalities may only receive 

retirement credit if such vehicles are sold outside the state; municipal fleets cannot 

currently receive credit if the vehicle is sold in state, unless BACT is applied. This 

change would allow private sweeper fleet operators to purchase cleaner used sweepers 

to comply with the proposed regulation, thereby lowering their cost to clean up their 

vehicles. 

N. Privately-Owned Utilities Alternative Proposal 

Privately-owned utility fleets are currently subject to the existing Public Agencies and 

Utility On-road Heavy-duty Diesel-fueled Vehicles Regulation, and must apply BACT to 

all of their vehicles, depending on model year, by December 31, 2011. Staff has 

proposed to include these fleets within the applicability of the proposed regulation. This 

has created concern among affected privately-owned utility fleets that are currently 

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-264- 

accelerating the purchase of vehicle with 2007 and newer model year engines to meet 

the PM requirements. 

To address this, a number of the private utilities in California proposed a delay in 

meeting the Pubic Agency and Utility On-road Heavy-duty Diesel-fueled Vehicles 

requirements that would allow them to purchase more 2010 and 2007 and later model 

year engines rather than installing more PM retrofits. Information supplied by the 

utilities show that utility fleet vehicles operate an average of 7,800 miles per year and 

typically buy new vehicles and use them for 12 to 20 years. Staff evaluated the utility 

proposed option and agreed that it was appropriate to make changes to the existing 

regulation for Pubic Agency and Utility On-road Heavy-duty Diesel-fueled Vehicles to 

provide an option to delay the remaining PM requirements by 2 years while adding 

requirements that, by 2013, at least 30 percent of the vehicles in the fleet must have 

2010 model year engines, and an additional 20 percent must have 2007 or newer 

engines. All other vehicles would need to meet the BACT requirements for PM. In 

addition, staff is proposing to require these fleets to meet the PM and NOx performance 

standards of the proposed In-Use Heavy Duty Vehicle Regulation beginning 

January 1, 2021. 

Overall, staff believes their proposal will provide an overall net air quality benefit. As 

such, staff believes that it is appropriate to provide the proposed option so that private 

utility fleets may purchase more 2010 and later model year engines to meet the BACT 

provisions of the fleet regulation for Public Agencies, which will provide additional long 

term NOx benefits relative to the current regulatory structure, and because the proposal 

would provide the same PM benefits in 2014 and beyond, consistent with the other 

vehicles subject to the proposed regulation. 

O. Workover Rigs 

Currently, the idling regulations restrict idling to five minutes, with certain exceptions for 

where idling is required to perform a specific job function. The regulations also require 

that the engine automatically shut off after five minutes of idling without interaction from 

the driver. Typically, in vehicles PTO, the engine shutdown system is normally 

overridden when in PTO mode. For most vehicles this occurs when a vehicle’s engine 

is idling and the engine’s power is used to perform certain specialized non mobile 

functions. However, unlike other vehicles, workover rigs use PTO to propel the vehicle 

and do not use PTO to power the specialized work while stationary. To address this, 

staff is proposing changes to the idling regulations to exempt workover rigs from the 

motor vehicle idling limit while they are performing the work for which the vehicle was 

specially designed. This proposal would allow a workover rig to carry out its specialized 

function when the vehicle is stationary and the engine is working. 

P. Other Changes 

1. Public Agency and Utility On-road Heavy-duty Diesel-fueled Vehicles 

Staff is proposing other changes to this regulation that would: 
-265- 

• expand the scope and applicability of the regulation to include light heavy-duty 

engines that were inadvertently omitted from the original scope of the regulation 

• address concerns with the introduction of 2007 model year and newer engines 

certified under the ABT provisions at PM levels greater than the 2007 model year 

standard of 0.01 g/bhp-hr, and; 

• provide a means of ensuring that vehicle owners get BACT credit for vehicles sold 

out of state and that vehicles sold out of state cannot be re-sold in California unless 

they met the BACT requirements 

These revisions are consistent with the original intent of the regulation to require 

upgrades of all engines that did not meet the PM BACT standard of 0.01 grams per 

brake horsepower hour, and will help fleets subject to this regulation ensure that they 

receive proper compliance credit for their actions.

2. In-Use Off-Road Diesel Vehicle Regulation 

Staff is proposing to modify section 2449 (e)(7) to clarify the exemption provision for 

low-use vehicles. The current regulatory language in the section exempts low-use 

vehicles from all of the performance requirements in section 2449(d). In proposing that 

regulation, it was not the intent of staff to exempt low use vehicles from those 

provisions. The proposed modifications would require low-use vehicles to comply with 

the requirements for adding vehicles to a fleet and with the idling requirements, 

consistent with staff’s original intent, and with how other off-road vehicles are covered. 

Also, new language is proposed in the In-Use Off-Road Diesel Vehicle Regulation that 

would clarify the repower requirements for workover rigs (and other on-road vehicles 

subject to that regulation). This new language would require that any replacement 

engine must be an on-road engine if the workover rig is to be registered and driven on 

public roadways. This is to clarify that, as new, these vehicles should have had on-road 

engines installed in them. 

3. Purpose and Definitions of Diesel Particulate Matter Control Measure 

Under the current definition of “municipality”, agencies of the United States of America 

are subject to the regulation for municipality and utility heavy-duty diesel vehicles. 

However, it was determined that CAA section 118 did not require federal fleet operators 

to comply with the municipality and utility fleet regulation because the regulation did not 

generally apply to nongovernmental entities. 

Staff’s proposal would amend the definition of municipality by excluding federal 

agencies from the municipality and utility fleet regulation. Consequently, fleets owned 

by the federal government would then be subject to the proposed regulation. In 

addition, staff is including tribal reservations and Rancherias because the sovereign 

nature of tribes is similar to the federal government. 
-266- 

4. Mobile Cargo Handling Equipment 

Staff examined the environmental impacts of removing both single-engine and 

two-engine mobile cranes and sweepers from the Cargo Handling Equipment 

Regulation. This would affect approximately 30 cranes and 40 sweepers statewide. 

Staff’s analysis showed that the affected equipment is responsible for only about 

one percent of the overall statewide cargo handling equipment emissions (or 0.006 tons 

per day of diesel PM and 0.14 tons per day of NOx in 2008). Complying with the OffRoad and proposed regulations would, in some cases, delay compliance until after the 

more stringent 2010 on-road and final Tier 4 off-road engine standards take effect. This 

would slightly decrease near-term reductions, but enhance the long term emission 

reductions are expected to be greater, particularly for cranes, which have long useful 

lives. 

Q. References 

ARB, 2007a, Air Resources Board. CEFS 2007. Available at: 

http://www.arb.ca.gov/ei/emissiondata.htm

ARB, 2007b. California Air Resources Board. EMFAC2007. Available at: 

http://www.arb.ca.gov/msei/onroad/latest_version.htm 

ARB, 2008. Air Resources Board. Regulation for In-Use Off-Road Diesel Vehicles. 

June 15, 2008. http://www.arb.ca.gov/regact/2007/ordiesl07/frooal.pdf

US BLS, 2008, US Bureau of Labor Statistics. Crane Related Occupational Fatalities 

Fact Sheet July 2008. 

MachineryTrader, 2008. Machinery Trader. Construction Equipment for Sale: Crane. 

October 5, 2008. www.machinerytrade.com

Sierra, 2008. Sierra Research. Letter From Gary Rubenstein of Sierra Research to 

Tony Brasil of ARB with attachments. March 14, 2008. 

Sierra, 2007. Sierra Research. Letter From Allan Daly to Clerk of the Board of ARB of 

ARB with attachments. March 21, 2007.Cranes 
-267- 

XVII. ENFORCEMENT

As in all its programs, it is the goal of the ARB to ensure uniform compliance across the 

industry, so that no one entity obtains an unfair economic advantage by not complying 

with the requirements of the regulation. This chapter discusses ARB preliminary plans 

regarding enforcement of the proposed regulation. 

A. Overview 

Any heavy-duty diesel vehicle traveling in California, including vehicles registered in 

other states and foreign countries, is subject to ARB inspection. Enforcement activities 

will have to increase significantly for staff to accomplish the program’s goal of consistent 

enforcement of the proposed regulation. Successful enforcement of the proposed 

regulation will depend on other important elements of the ARB’s enforcement program. 

These include active outreach to regulated industries and training and compliance 

assistance. Given the complexity of the proposed regulation and the many critical 

decisions that fleets will have to make, there could be a large number of fleets that will 

seek staff’s assistance. Staff will be available to help those fleets that do request such 

assistance. 

For heavy-duty vehicles, current enforcement activities for existing regulations include 

inspections at border crossings, California Highway Patrol (CHP) weigh stations, fleet 

facilities, randomly selected roadside locations, and audits of records. ARB’s 

enforcement staff currently uses the inspection and audit methods they have developed 

during their many years of experience enforcing the Heavy-Duty Vehicle Inspection 

Program, the Periodic Smoke Inspection Program, and in coordination with CHP staff. 

B. Planned Enforcement Activities for Proposed Regulation 

ARB’s enforcement staff will use the inspection and audit methods they have developed 

during their many years of experience enforcing the Heavy-Duty Vehicle Inspection 

Program (adopted into law in 1988) and the Periodic Smoke Inspection Program 

(adopted into law in 1990). Enforcement activities will include inspections at border 

crossings, CHP weigh stations, fleet facilities, and randomly selected roadside 

locations, and audits of records. These activities could result in corrective actions and 

substantial civil penalties for non-compliance with the regulation. 

The critical elements to the successful enforcement of the proposed regulation would be 

the annual reporting, if using the BACT percentage limits or the fleet averaging option, 

or vehicle inspections if the BACT option is used. Reporting will allow staff to initially 

determine whether fleets have either met the fleet average targets or complied with the 

BACT percentage limits requirements. Fleets would report each vehicle, its vehicle 

identification number (VIN), its engine data, its model year, as well as any actions taken 

to comply. For vehicles claiming one of the exemptions from the NOx or PM 

requirements, owners will report the appropriate information such as miles driven, 

location where miles occurred, hours of use, and date of installation of control 

technology. 
-268- 

Fleets that report noncompliance with any of the proposed PM and NOx performance 

requirements will automatically be subject to enforcement action, as will fleets choosing 

to use the fleet averaging option or the BACT percentage limits option that do not report 

at all. Fleets that submit questionable annual reports will also be subject to follow-up 

inspections and possible enforcement action. An annual report that appears 

appropriate will not preclude its fleet from an ARB audit. 

Each vehicle that installs a verified DECS will need to carry in the cab of the vehicle 

documentation demonstrating proper installation and proof that the device has been 

verified by ARB. When ARB inspectors conduct a business audit, they will be able to 

link the VIN or the engine serial number to whatever action was claimed for that vehicle. 

They will be able to tell if the vehicle does not have the engine claimed, or is not 

outfitted with the retrofits claimed or whether the retrofits have been correctly installed. 

Even though in most cases inspectors may not be able to view an owner’s entire fleet 

because it will be dispersed in various locations, inspectors will be able to verify 

compliance for whatever vehicles they encounter. If inspectors find vehicles without the 

retrofits that were reported or with different model engines that were reported, fleets 

would be subject to enforcement action. 

If inspectors find vehicles that choose to utilize retrofit technology to comply with the 

regulation but are not carrying the proper verified DECS documentation, then that will 

be an immediate indication of noncompliance. Vehicles driving in from out-of-state will 

need to carry the same documentation. 

ARB inspectors may use a variety of opportunities to find and inspect vehicles that are 

subject to the regulation. For example, they may conduct audits of fleets at facilities 

including but not limited to truck stops, weigh stations, and temporary roadside 

inspection facilities. They may also inspect truck terminals at business facilities or at 

ports and rail stations. A search of CHP’s Biennial Inspection of Terminals database 

may also provide a way to target inspectors toward larger trucking terminals. 

They may also inspect vehicles at the border crossings where vehicles are routinely 

inspected for produce. Finally, inspections may be triggered if ARB receives reports 

from the public that indicate that certain vehicles has been observed with smoking 

exhaust or that a fleet is not in compliance with the rule. 

Enforcement of the rule will be conducted similarly to enforcement of ARB’s commercial 

vehicle and school bus idling rules. Complaints from the public via calls to the 1-800-

END-SMOG toll-free line or on-line reporting trigger inspections or further enforcement 

action. 

Staff would provide public access to the names of the companies who have reported. 

While details of each fleet and its compliance strategy would not be made public, the 

public would be able to search the reporting database to confirm whether companies 

they are considering hiring have reported and submitted the required certifications of 

compliance. This would allow motor carriers, brokers, and others wishing to hire 
-269- 

compliant trucking firms an avenue to ensure they hire only fleets that have reported 

their data to ARB or can demonstrate compliance with the regulation. The system 

would also allow companies to check whether their competitors have complied with 

regulation. If a motor carrier is considering hiring a trucking company or an owneroperator to move goods, it can check the reporting database and at least see if the 

company reported that it is complying using the fleet averaging or BACT percentage 

limits if it chose that option to comply. Because the rule would impose significant costs, 

to ensure a level playing field, it would be important to ensure that firms who are 

competing against one another are all complying. Certain business and professions 

codes that protect fair competition may be used against a non-complying firm. 

ARB would have the responsibility for enforcing the proposed rule. From time to time, 

local air district staff may encounter vehicles that they believe are not in compliance with 

the proposed regulation. In addition, district inspectors may observe or be told by the 

public of situations where vehicles are smoking excessively. In these situations, the 

district staff could notify ARB staff so that ARB staff can take appropriate enforcement 

action. 

C. Need for Additional Resources 

The proposed regulation would affect over 400,000 in-state only or over 900,000 both 

in-state and out-of-state on road diesel vehicles operating in California, including 

vehicles registered in other states and foreign countries. To ensure uniform compliance 

across the industry, guarantee no one entity obtains an unfair economic advantage by 

not complying with the requirements, and to achieve the emission reductions projected 

for the proposed regulations, enforcement activity will need to increase significantly. 

Subsequently, existing staffing levels will need to be increased to meet the increased 

demand for inspections and other enforcement activities. 

It is also anticipated additional staffing would be required to conduct implementation and 

outreach activities such as statewide training workshops, seminars, trade show 

presentations, and booths conferences and expositions. Staff further anticipates an 

increase in requests for information and assistance, the development of compliance 

guidance documents and other tools to assist potential stakeholders with 

implementation. A web based regulatory tracking system for fleet reporting, 

enforcement verification purposes, and status reports on the rule’s implementation 

would be required. 

In addition, additional contracting with CHP staff will likely be required for enforcement. 

Based on the cost of CHP participation under the current scope of ARB’s field 

enforcement activities, and the projected increases in roadside inspections required for 

enforcement of the regulation, additional funding would also be required. 
-270- 
-271- 

XVIII. ALTERNATIVE CONSIDERED

Throughout the regulatory development process, staff considered a number of 

alternative possible approaches to the rule structure. The alternatives considered and 

reasons they were rejected in favor of the chosen proposed regulation are provided in 

this chapter. 

In developing the regulation, staff considered the following goals: 

• Achieve the maximum, fastest possible, reductions in toxic PM emissions; 

• Maximize NOx reductions to aid in attainment of federal air quality standards in the 

South Coast and San Joaquin Valley; 

• Meet the SIP commitments 

• Minimize the costs for fleets and, in particular, minimize the frequency of fleets 

replacing existing vehicle with new vehicles; 

• Achieve cost-effective emission reductions on a dollar per ton basis. 

Staff sought to achieve these goals while considering the technology available today, as 

well as the technology that is likely to become available in the future. 

Overall, the proposed regulation was selected as the best regulatory structure. It meets 

the goals of maximizing necessary PM and NOx emission reductions by cost-effective 

emission reductions. The proposed regulation provides flexibility in that it allows fleets 

to choose one of three compliance options each year. Small fleets (3 or fewer vehicles) 

are given additional time for compliance, and the regulation provides credit for both 

early actions to reduce PM emissions and the use of hybrid and alternative fuel 

vehicles. The proposed regulation also has lesser requirements for vehicles with lower 

usage, for those that drive exclusively in NOx-exempt areas, and for agricultural 

vehicles. 

A. Retrofit Only Regulation 

Staff considered a traditional BACT PM retrofit only regulation. This is similar to 

previous adopted regulations for solid waste collection vehicles, transit and urban bus 

fleets, and public and utility fleets. Such a regulation would require fleets to phase-in a 

certain percent of PM retrofits each year until all vehicles are retrofit in the fleet. Such a 

regulation would achieve the goal of maximizing the fastest possible reductions in PM 

emissions. A retrofit-only regulation would also achieve some NOx emission reductions 

as a result of replacing vehicles with newer vehicles in lieu of retrofits. It could also 

result in lower costs for fleets and minimize the need for fleets to replace existing 

vehicles with new vehicles since there are many PM-only retrofits available that are not 

as expensive as retrofits that achieve both PM and NOx reductions, or as expensive as 

replacing the engine or vehicle. 

Although this proposal would maximize the necessary PM emission reductions, it would 

fall significantly short of achieving the NOx emissions needed for attainment of federal 

air quality standards in the South Coast and San Joaquin Valley Air Basins. Substantial 
-272- 

NOx emission reductions are needed not only to achieve federal air quality standards 

but also to meet progress requirements for the ozone standard required under California 

state law. 

B. August 2007 ARB Staff Proposal 

Staff’s first draft proposed regulatory language was presented at public workshops held 

in August, 2007. The proposal consisted of requiring the application of NOx and PM 

BACT in two phases, optional fleet averaging provisions for non-interstate vehicles, or a 

combination of the two requirements. This two-phase approach is shown below in 

Table XVIII-1. 

Table XVIII-1: August 2007 ARB Staff Proposed BACT Schedule 

Phase Standard Engine Model Year Compliance Date 

(December 31) 

Pre 1994 2009 

1994 – 1997 2010 

1998 – 1999 2011 

2000 – 2002 2012 

Phase 1 

2004 and later 

MY engine 

with highest 

level DECS 

2003 – 2006 2013 

Pre 2003 2017 

Phase 2 2003 – 2004 2018 

2007 and later 

MY engine 

2005 – 2006 2019 

For Phase 1, meeting the BACT requirement included replacing a vehicle with a vehicle 

equipped with an engine that met the 2004 and later emission standards, and had the 

highest level verified DECS, or applying a verified DECS that, when applied, provided 

equivalent NOx and PM emission reductions. In Phase 2, beginning in 2017, all 

vehicles would have had to meet or exceed the emissions standards of a 2007 and later 

model year engine by the end of 2020. Compliance with these requirements could have 

included replacing an older vehicle with a new or used cleaner vehicle, installing a 

cleaner engine, retrofitting an existing vehicle, and/or retiring older, dirtier vehicles. 

The proposed fleet averaging option applied only to fleets that are registered to 

exclusively operate in California. To use the fleet average option, each year fleets 

would have had to demonstrate that, their fleet average emission rate was less than the 

fleet average emission target rate as shown in Figure XVIII-1. This compliance option 

also required that by December 31, 2019, all vehicles must meet engine model-year 

2007 PM and NOx emissions standards. Staff also proposed special provisions for low 

use vehicles (less than 1000 miles and less than 100 hours per year), vehicles used for 

emergency operations, manufacturer delays, and use of experimental diesel control 

technology. The staff also proposed credit for use of diesel hybrid electric vehicles and 

alternative fuel vehicles. 
-273- 

Figure XVIII-1: August 2007 ARB Staff Proposed Fleet Average PM and NOx 

Emission Targets 

While this proposal would have maximized PM emissions reductions by 2014 (this 

proposal would have provided equivalent PM reductions to the proposed regulation), it 

did not provide the NOx emission reductions needed to meet the State’s SIP 

commitments in the San Joaquin and South Coast Air Basins. As a result, this 

alternative was not considered. 

In addition, this proposal did not minimize the costs to fleets, especially owner-operator 

type fleets or small fleets with three or fewer vehicles. It also did not minimize the need 

for engine or vehicle replacement. 

C. January 2008 ARB Staff Proposal 

Staff again revised its proposed regulatory language and presented it at the series of 

public workshops held in January and February 2008. The proposal was modified to 

reflect the modernization program envisioned in the 2007 SIP. 

The January 2008 proposal consisted of revised NOx and PM BACT requirements, 

more stringent fleet averaging provisions, and new special provisions for small fleets 

and specialty vehicles. It also contains special provisions for low mileage vehicles and 

vehicles that travel exclusively in certain less polluted areas in California. Staff also 

scaled back the applicability of the proposed regulation by excluding pickups and other 

vehicles with GVWR less than 14,000 pounds (except diesel shuttle buses), emergency 

vehicles, tactical military vehicles, and personal use motor homes. 

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Again, staff proposed a two-phase NOx and PM BACT schedule, but revised the NOx 

BACT requirement to require compliance in Phase 1 with a vehicle equipped with an 

engine that met the 2007 and later emission standard by 2014. In the second phase, 

the NOx BACT requirement was strengthened to require a vehicle equipped with an 

engine that met the 2010 and later emission standard by 2022. Table XVIII-2 outlines 

the proposed two-phase BACT schedule in the January, 2008, staff proposal. 

Table XVIII-2: January 2008 ARB Staff Proposed BACT Schedule 

Phase Standard Engine Model Year Compliance Date 

(December 31) 

Pre 1998 2010 

1998 – 2002 2011 

2003 – 2004 2012 Phase 1 2007 and later 

MY engine 

2005 and newer 2013 

Pre 2004 2017 

2004 – 2006 2018 

2007 2019 

2008 2020 

Phase 2 2010 and later 

MY engine 

2009 2021 

In the January 2008 ARB staff proposal, staff proposed a fleet averaging compliance 

option that would have allowed a mix of cleaner and dirtier engines, and would have 

applied to all vehicles in a fleet, regardless of the origin of the vehicle’s registration (just 

as the current fleet average provision in the proposed regulation does). This 

compliance option would have required fleets to have achieved 2007 model-year 

equivalent emission reductions from 25 percent of their fleet by the end of 2010, 50 

percent by the end of 2011, 75 percent by the end of 2012, and 100 percent by the end 

of 2013. Similarly, the fleets would have had to achieve 2010 model-year equivalent 

emission reductions from their fleet by 2021. Figure XVIII-2 shows the fleet average 

emission targets that fleets would have to meet at the end of each compliance year. 
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Figure XVIII-2: January 2008 ARB Staff Proposed Fleet Average Emission 

Targets 

ARB staff also proposed a new, special provision for small fleets. Under this provision, 

small fleets were defined as a fleet with three or fewer vehicles. A fleet with one vehicle 

would have been required to upgrade the vehicle to a 2007 emission equivalent engine 

by the end of 2012. A fleet with two vehicles would have been required to upgrade to a 

2007 emissions equivalent engine by the end of 2011 for the first vehicle and by the end 

of 2013 for the second vehicle. Fleets with three vehicles would have been required to 

upgrade to a 2007 emissions equivalent engine starting in 2010. Table XVIII-3 shows 

the ARB staff’s January 2008 proposed compliance schedule for small fleets. 

Table XVIII-3: January 2008 ARB Staff Proposed Compliance Schedule for 

Small Fleets 

Fleet Size Upgrade to 2007 Equivalent Engine 

(by December 31) 

1 Vehicle 2012 

2 Vehicles 2011 and 2013 

3 Vehicles 2010, 2012, and 2013 

Staff also proposed requiring public utilities (which are subject to the provisions of the 

Fleet Rule for Public Agencies and Utilities) to upgrade to 2010 engine emissions 

between 2017 to 2021, providing double credit for hybrid vehicles, and additional credit 

for existing alternative fueled vehicles. ARB staff also proposed incorporating twoengine cranes into ARB’s In-Use Off-Road Diesel Vehicle Regulation, and added PM 

only retrofit requirements for school buses. 
-276- 

Figure XVIII-3 compares the NOx emissions of the ARB January, 2008, proposal to the 

emissions of the current staff proposal. In this case, staff did not model the phase-in of 

the January proposal, and instead modeled a simple case that assumed compliance by 

2014 and 2020. Figure XVIII-3 shows that in 2014 and 2020 the ARB January proposal 

would have resulted in more NOx reductions than the current staff proposal in 2014 but 

less reductions in 2017. Figure XVIII-4 shows that the January 2008 proposal would 

have achieved essentially the same PM2.5 emissions reductions as the current staff 

proposal. 

Figure XVIII-3: ARB January Proposal (NOx Emissions) 

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January 2008 Proposal
-277- 

Figure XVIII-4: ARB January Proposal (PM Emissions)

However, while this approach achieved additional emission reductions relative to the 

proposed regulation in 2013, it did not allow most fleets much opportunity to spread out 

their vehicle replacements past the 2014 period. It would also have created greater 

demand for 2007 model year engines, and would have resulted in higher capital 

investments in the first four years relative to the current proposal. Staff estimates that 

this approach would have resulted in additional regulatory costs of about $1 billion 

relative to the proposed regulation. Additional information about staff’s analysis is 

provided in Appendix N. 

D. Street Sweeper Industry Proposal 

Staff also considered a regulatory proposal from the California Chapter of the North 

American Power Sweeping Association (NAPSA). The proposal included a schedule for 

phasing out older sweeper vehicles through 2022. Under this proposal, by 2022, 

sweeper fleets would be required to have 50 percent of their fleet with 2007 or newer 

model year engines (NAPSA, 2008). The proposal also included provisions to exempt 

certain types of sweepers from existing diesel emission regulations that apply to the 

auxiliary engine on two-engine sweepers, and to exempt from the proposed regulation 

sweeper fleet owners with two or fewer sweepers that do not sweep for hire or in a 

commercial capacity. 

As shown in Table XVIII-4, the proposed phase-out schedule began in 2011, with 

sweeper fleets being required to retire or remove 1979 and older vehicles, limiting the 

mileage on 1980 to 1989 model year sweepers, and allowing 1990 and newer model 

year sweepers to continue to operate uncontrolled until 2018. Beginning in 2018, 

sweepers with model year engines 1980 to 1989 would have to be retired, 1990 to 1997 

model year sweepers would be permitted to operate with limited mileage, and 1998 and 

newer vehicles would continue to operate uncontrolled. Finally, in 2022, vehicles with 

model year engines 1990 to 1997 would have to be retired, 1998 to 2006 model year 

0

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20

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30

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PM (tpd)

Baseline

Proposed Regulation

January 2008 Proposal
-278- 

engines would be permitted to operate with limited mileage, and fleets would be 

required to have 50 percent of their fleet with sweepers with 2007 or newer model year 

engines, while the remaining 50 percent of their vehicles could operate uncontrolled. 

Table XVIII-4: NAPSA July 2008 Proposal for Street Sweepers 

Compliance Year Model Year Requirement 

Pre - 1979 Retire 

1980 – 1989 Operate less than 15,000 

miles per year 2011 

1990 and newer Unlimited operation 

1980 – 1989 Retire 

1990 – 1997 Operate less than 15,000 

miles per year 2018 

1998 and newer Unlimited operation 

1990 – 1997 Retire 

1998 – 2006 Operate less than 15,000 

2022 miles per year 

Fleets required to have 50% of fleets with 2007 or 

newer engines 

NAPSA also proposed that the Fleet Rule for Public Agencies and Utilities be modified 

to allow public agencies to receive retirement credit for in-state sales of used sweepers 

and provide double credit for public agencies selling sweepers to comply with that rule. 

ARB staff considered the proposal from NAPSA and met a number of times with 

representatives to discuss the proposal and their concerns. Staff estimates that there 

are about 1,250 to 2,000 sweepers operating in California that would be subject to the 

proposed regulation. Although the proposal would substantially reduce the regulatory 

costs to sweeper fleets, it would also forgo a substantial percentage of emission 

reductions of both PM and NOx from these vehicles. Since sweepers frequently 

operate in urban areas, and especially residential neighborhoods, staff was concerned 

that the loss in reductions of diesel PM emissions could result in a substantial loss in the 

anticipated risk reductions provided by the proposed regulation. In addition, the loss of 

both PM and NOx reductions from these vehicles would reduce the overall emission 

reductions needed from the proposed regulation to meet the state’s SIP commitments in 

the San Joaquin Valley and South Coast air basins. Additional information about staff’s 

analysis is provided in Appendix M. 

However, staff recognized that the street sweeper industry is subject to multiple ARB 

regulations, including the Portable Equipment ATCM, the Mobile Cargo Handling 

Equipment at Ports and Intermodal Rail Yards regulation, and the proposed regulation. 

Each of these regulations has different compliance requirements on various sweeper 

engines at different times. In addition, the private sweeper industry has historically 

purchased used sweepers from municipalities. However, under the Fleet Rule for 

Public Agencies and Utilities, municipalities cannot receive BACT credit unless they sell 
-279- 

a non-compliant sweeper (that is, one that has not had BACT applied to it) out of state. 

This has essentially stopped the supply of used sweepers for the California private 

sweeper industry. 

In order to streamline complying with these various regulations, and to continue to 

realize emission reductions from these sweepers, staff has proposed special provisions 

for certain two-engine sweepers, while clarifying the applicability of these other 

regulations to two-engine sweepers. In addition, to increase the supply of cleaner, used 

municipal sweepers, staff is proposing to allow municipalities the ability to obtain BACT 

credit (in the Fleet Rule for Public Agencies and Utilities) for the sale of a two-engine 

sweeper with a 2004 and later propulsion engine to a private sweeper operator. 

E. Driving Toward a Cleaner California Proposal 

“Driving Toward A Cleaner California” (DTCC) is a coalition of business leaders and 

industry representatives that developed an alternative proposal in response to the 

proposed regulation. The DTCC proposal includes: 

• more generous mileage exemptions; 

• early incentives; 

• specialty vehicles provisions; 

• a less aggressive compliance schedule for businesses subject to two or more ARB 

regulations; 

• consideration of safety and compatibility issues, and; 

• more flexible provisions if diesel emission control technology is not available. 

The proposal would retain the same three compliance options in the proposed 

regulation, but would modify the compliance schedule and requirements. It also would 

add a fourth compliance option which would apply only to single units vehicles. 

DTCC also proposed revisions to increase the mileage exemptions for certain model 

year engines. As shown below in Table XVIII-5, starting December 31, 2010, 2004 or 

newer model year engines would be exempt from any performance requirements if their 

mileage is less than 30,000 miles per year. After December 31, 2020, these vehicles 

would be required to be replaced with vehicle having 2010 or newer model year 

engines. 

For vehicles driven less than 15,000 miles per year, but more than 7,500 miles per year, 

1994 or newer engines with level 3 PM diesel control technology installed would be 

exempt from any further performance requirements until December 31, 2020. Starting 

December 31, 2020, these vehicles would have to be replaced with a vehicle having a 

2007 or newer model year engine, and the mileage would need to remain below 15,000 

miles per year. For vehicles driven less than 7,500 miles per year, vehicles with level 3 

PM diesel control technology installed would be exempt from any performance 

requirements until December 31, 2020. After December 31, 2020, vehicles would have 
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to be replaced with a vehicle having a 2004 model year or equivalent engine, and the 

mileage would need to remain below 7,500 miles per year. 

Table XVIII-5: DTCC Proposal for Mileage Exemptions

Annual Mileage Engine Model 

Year/Technology 

Exemption End Date 

(December 31) 

2004 or newer 2020 Up to 30,000 2010 or newer N/A 

1994 with Level 3 DECS 2020 Up to 15,000 2007 or newer N/A 

Level 3 DECS 2020 Up to 7,500 2004 or newer N/A 

DTCC also proposed that fleet owners who purchase and operate 2007 or newer model 

year engines or equivalent and are not subject to the drayage truck regulation before 

December 31, 2009, would get 2 additional years, starting December 31, 2020, to 

comply under the current proposed BACT schedule for 2007 or newer model year 

engines. In addition, DTCC proposed that by December 31, 2012 dedicated use or 

single unit vehicles meet a 1994 or later model year engine standard and have a level 3 

diesel PM control technology installed. These vehicles would then have to meet a 2007 

engine standard in 2020. 

• DTCC also proposed that the staff should be required to address any and all safety 

concerns and allow for specific exemptions related to emission reduction technology 

and safe operation, including the transport of hazardous or flammable materials and 

other considerations, and that staff should develop a personalized compliance 

schedule for businesses subject to two or more ARB regulations. The schedule 

would allow compliance on a schedule which considers the financial impacts of all 

regulations rather than the schedule required by each regulation. 

DTCC also proposed changes to the BACT implementation schedule that would delay 

any of the NOx BACT performance standards until 2014. DTCC’s proposed changes to 

the BACT schedule are shown below in Table XVIII-6. 
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Table XVIII-6: DTCC Proposed BACT Schedule 

Compliance Deadline (as 

of December 31) 

Engine Model Years BACT Requirements 

2010 Pre - 1994 PM BACT 

2011 1994 – 1997 PM BACT 

2012 1998 – 2003 PM BACT 

2013 2004 – 2006 PM BACT 

2014 Pre – 1994 NOx and PM BACT 

2015 1994 – 1997 NOx and PM BACT 

2016 1998 – 2003 NOx and PM BACT 

2017 2004 – 2006 NOx and PM BACT 

2018 NA NA 

2019 NA NA 

2020 2007 NOx and PM BACT 

2021 2008 NOx and PM BACT 

2022 2009 NOx and PM BACT 

DTCC also proposed changes to the proposed fleet averaging provisions. This 

including counting vehicles retired in a fleet before December 31, 2010, as 2010 

compliant until December 31, 2017, for purposes of fleet averaging. Under the DTCC 

proposal, each retired vehicle would count as a 2010 model year equivalent and would 

be included in the total fleet average until 2017. The proposal also would, in general, 

delay the NOx fleet average emission targets. However, the PM fleet average emission 

targets would remain the same as in the proposed regulation. 

DTCC also proposed changes to the BACT percent limit provisions, which would, in 

general, delay the NOx BACT percent limits. However, the PM fleet average emission 

targets would remain the same, for the most part, as in the proposed regulation. DTCC 

proposed BACT percent limits are shown in Table XVIII-7. DTCC also proposed that 

vehicles retired be counted as a BACT compliant vehicle in a fleet before the end of 

each compliance year. 
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Table XVIII-7: DTCC Proposed BACT Percent Limits 

Compliance Deadline (as Percentage of Total Fleet Complying with BACT 

of December 31) PM BACT NOx BACT 

2010 25% NA 

2011 25% NA 

2012 50% 25% 

2013 100% 25% 

2014 100% 50% 

2015 100% 50% 

2016 100% 75% 

2017 100% 75% 

2018 100% 80% 

2019 100% 90% 

2020 100% 90% 

2021 100% 90% 

2022 100% 100% 

Staff analyzed the four main provisions of the proposal together. The results are shown 

in Figure XVIII-5 for NOx and Figure XVIII-6 for PM. The primary difference between 

the DTCC proposal and the proposed regulation is the rate at which emissions benefits 

are realized. The proposed regulation would achieve substantially more reductions 

between 2012 and 2020. Beginning in 2021, the DTCC proposal would achieve similar 

emissions benefits to the proposed regulation. Overall, the DTCC proposal would 

achieve roughly half of the emissions benefits that would be achieved by the proposed 

regulation. The DTCC proposal would not meet California’s SIP commitments in any 

year. Additional information about staff’s analysis is provided in Appendix N. 
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Figure XVIII-5: DTCC Stakeholder Proposal (NOx Emissions) 

0

100

200

300

400

500

600

700

800

2010201120122013201420152016201720182019202020212022202320242025

NOx (tpd)

Baseline

Proposed Regulation

DTCC Proposal

Figure XVIII-6: DTCC Stakeholder Proposal (PM Emissions) 

0

5

10

15

20

25

30

2010201120122013201420152016201720182019202020212022202320242025

PM (tpd)

Baseline

Proposed Regulation

DTCC Proposal
Addendum to the 

TECHNICAL SUPPORT DOCUMENT: 

PROPOSED REGULATION FOR IN-USE ON-ROAD DIESEL VEHICLES 

(ARB, October 2008) 

The following references are added to the chapters and appendices in the Technical 

Support Document: Proposed Regulation for In-Use On-Road Diesel Vehicles: 

Chapter XVI. RATIONALE FOR REGULATORY PROVISIONS AND CHANGES TO 

OTHER REGULATIONS 

In section J, School Buses, general concepts regarding children’s 

exposure to diesel emissions from school buses were discusses but the 

reference was omitted and is added below: 

Berhrentz, 2005. Berhrentz, E., Sabin, L., Winer, A., Fritz, D., Pankratz, 

D., Colume, S. and S. Fruin, 2005, Relative Importance of School BusRelated Microenvironments to Children’s Pollutant Exposure. Journal of 

Air & Waste Management Association., p. 1418 – 1430. 

Chapter XIII. COST SUMMARY AND METHODOLOGY and 

Chapter XIV. ECONOMIC IMPACTS and 

Appendix J. COST AND ECONOMIC ANALYSIS METHODOLOGY 

The terms “cost model” and “ARB On-Road Compliance Model” were 

used in numerous places throughout Chapter XIII and Chapter XIV. The 

term is explained in detail in Appendix J, but the model was not 

referenced. The following reference needs to be added to each chapter: 

ARB Model, 2008. On-Road Capital Cost Model, Air Resources Board 

www.arb.ca.gov/dieseltruck. 

Chapter XIII. COST SUMMARY AND METHODOLOGY 

Section B. 2. a) discussed the data on vehicle prices that were 

downloaded from www.truckpaper.com. The reference,

Truckpaper.com, was discussed, however, the proper citation was not 

included in the paragraph or in the list of references. The proper 

reference is the following: 

Truckpaper.com, 2008b. www.truckpaper.com 

 
Page 2

Chapter XIV. ECONOMIC IMPACTS 

In Section C. 1. e), references to the 2008 Land Line Reader Survey 

were made, but not cited. The reference below was omitted and is being 

added: 

Land Line, 2008. 2008 Land Line Reader Survey, Owner-Operator 

Independent Drivers Association (OOIDA), February 2008, 

www.ooida.com 

Chapter XIII. COST SUMMARY AND METHODOLOGY 

In Section B. 2. a), references to the National Automobile Dealers 

Association were made, but the reference was omitted and is being 

added. 

NADA, 2008. NADA Guides, Vehicle Pricing & InformationTM, 

www.nada.org 

Appendix J. COST AND ECONOMIC ANALYSIS METHODOLOGY 

Figure 13 in Chapter A., section7, was created using maintenance costs 

from an individual fleet requesting confidentiality but the reference was 

omitted and is being added below: 

Operating Cost, 2008. Truck Maintenance and Repair Costs from 

unnamed source. 

Appendix J. COST AND ECONOMIC ANALYSIS METHODOLOGY 

Table 20 and Table 21 were created using individual body transfer costs 

obtained through personal conversations with several people but the 

reference was omitted and is being added. 

Body Transfer Cost, 2008. Personal communications.