STAFF REPORT: INITIAL STATEMENT OF REASONS FOR PROPOSED 

RULEMAKING 

PROPOSED AMENDMENTS TO THE TRUCK AND BUS REGULATION, 

THE DRAYAGE TRUCK REGULATION AND THE TRACTOR-TRAILER 

GREENHOUSE GAS REGULATION 

Mobile Source Control Division 

Heavy-Duty Diesel Implementation Branch 

October 2010 

State of California 

AIR RESOURCES BOARD 

STAFF REPORT: INITIAL STATEMENT OF REASONS 

FOR PROPOSED RULEMAKING 

Public Hearing to Consider 

ADOPTION OF THE PROPOSED AMENDMENTS TO THE TRUCK AND BUS 

REGULATION, THE DRAYAGE TRUCK REGULATION AND THE 

TRACTOR-TRAILER GREENHOUSE GAS REGULATION 

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

will commence December 16, 2010, and may continue to December 17, 2010, at 

California Environmental Protection Agency 

Air Resources Board 

Byron Sher Auditorium 

1001 I Street 

Sacramento, CA 95814 

State of California 

AIR RESOURCES BOARD 

ADOPTION OF THE PROPOSED AMENDMENTS TO THE TRUCK AND BUS 

REGULATION, THE DRAYAGE TRUCK REGULATION AND THE 

TRACTOR-TRAILER GREENHOUSE GAS REGULATION 

This report has been prepared by the Mobile Source Control Division staff of the Air 

Resources Board with the assistance and support from the following divisions: Planning 

and Technical Support, Stationary Source, and Research. In addition, we would like to 

acknowledge the assistance and cooperation that we have received from many 

individuals and organizations. 

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. 

-iTABLE OF CONTENTS 

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

I. INTRODUCTION......................................................................................................... 9

A. BACKGROUND .................................................................................................... 9

B. REGULATORY AUTHORITY ................................................................................. 10

C. RATIONALE FOR THE PROPOSED AMENDMENTS................................................... 11

D. STAKEHOLDER PARTICIPATION........................................................................... 13

II. NEED FOR EMISSIONS REDUCTIONS ........................................................................ 17

A. UPDATES TO TRUCK EMISSIONS INVENTORY ....................................................... 17

B. CURRENT AND FUTURE EMISSIONS .................................................................... 19

C. MEETING AIR QUALITY STANDARDS ................................................................... 21

D. PM EMISSIONS AND MORTALITY ........................................................................ 23

E. EXPOSURE TO LOCALIZED DIESEL PM EMISSIONS............................................... 24

III. PROPOSED AMENDMENTS TO THE TRUCK AND BUS REGULATION.............................. 25

A. EXISTING REGULATION...................................................................................... 25

B. PROPOSED AMENDMENTS TO THE TRUCK AND BUS REGULATION ......................... 28

C. EFFECT OF PROPOSED AMENDMENTS ON AFFECTED FLEETS ............................... 35

IV. PROPOSED AMENDMENTS TO THE DRAYAGE TRUCK REGULATION............................. 41

A. EXISTING DRAYAGE TRUCK REGULATION............................................................ 41

B. PROPOSED AMENDMENTS ................................................................................. 41

V. PROPOSED AMENDMENTS TO THE TRACTOR-TRAILER GHG REGULATION ................. 43

A. EXISTING REGULATION...................................................................................... 43

B. PROPOSED AMENDMENTS TO THE TRACTOR-TRAILER GHG REGULATION............. 43

C. EFFECT OF PROPOSED AMENDMENTS ON INDIVIDUAL FLEETS .............................. 44

VI. ENVIRONMENTAL IMPACTS...................................................................................... 45

A. LEGAL REQUIREMENTS ..................................................................................... 45

B. EMISSION IMPACTS FROM PROPOSED AMENDMENTS ........................................... 45

C. IMPACT ON SIP TARGETS .................................................................................. 51

D. IMPACT ON PM MORTALITY ............................................................................... 51

E. IMPACT ON LOCALIZED RISK .............................................................................. 52

F. IMPACT ON CLIMATE CHANGE EMISSION ............................................................. 52

G. ENVIRONMENTAL JUSTICE AND NEIGHBORHOOD IMPACTS .................................... 53

H. OTHER ENVIRONMENTAL IMPACTS ..................................................................... 53

I. CONCLUSION.................................................................................................... 53

VII. ECONOMIC IMPACTS............................................................................................... 55

A. TRUCK AND BUS REGULATION AMENDMENTS ...................................................... 55
-iiB. EFFECTS OF AMENDMENTS TO THE DRAYAGE TRUCK REGULATION....................... 63

C. EFFECTS OF AMENDMENTS TO THE TRACTOR-TRAILER GHG REGULATION ............ 64

D. IMPACTS ON INCENTIVE FUNDING ....................................................................... 64

VIII. ALTERNATIVES CONSIDERED .................................................................................. 67

A. ALTERNATIVES CONSIDERED TO THE TRUCK AND BUS REGULATION...................... 67

B. ALTERNATIVES CONSIDERED TO THE DRAYAGE TRUCK REGULATION .................... 69

C. ALTERNATIVES CONSIDERED TO THE TRACTOR-TRAILER GHG REGULATION ......... 69

IX. REFERENCES......................................................................................................... 71
-iiiLIST OF TABLES 

Table E-1: Emissions Are Less Than the 2014 SIP Target Existing Truck and Bus 

and Off-road Regulations, Including Recession..................................... 10 

Table I-1: Ten Guiding Principles........................................................................... 12

Table I-2: Public Workshop Dates and Locations .................................................. 14

Table II-1: Emissions Are Less Than the 2014 SIP Target – Existing 

Truck and Off-Road Regulations, Including Recession ......................... 23

Table III-1: Current Best Available Control Technology Compliance Schedule ....... 26

Table III-2: Percent of Fleet That Must Comply with Current PM 

and NOx BACT Standard ...................................................................... 27

Table III-3: Proposed BACT Schedule for Heavy Weight Vehicles.......................... 29

Table III-4: Phase-In Option Schedule..................................................................... 30

Table III-5: Small Fleet Phase-In Option Schedule.................................................. 30

Table III-6: Example of Economic Relief for Fleet Downsized 25 Percent............... 31

Table III-7: Percentage of Log Trucks that Must have 2010 Model Year 

Emissions Equivalent............................................................................. 33

Table III-8: Phase-In Compliance Schedule for School buses Greater than 

26,000 lbs GVWR.................................................................................. 34

Table III-9: Existing and Proposed BACT Schedule Compliance Example.............. 35

Table III-10: Example of Adjusted Compliance Requirements for a Fleet 

That Downsized 23 Percent................................................................... 38

Table VI-1: Impact on Statewide NOx and PM Emissions ....................................... 45

Table VI-2: Benefits of the Current Regulation Compared to the 

Proposed Amendments (tpd)................................................................. 48

Table VII-1: Comparison of 2014 Actions Required (Percentage of Trucks)............. 56

Table VII-2: Cost Effectiveness Ratio Comparison ................................................... 57
-iv-
-vLIST OF FIGURES 

Figure E-1: Truck Contribution to 2010 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) .................................. 3 

Figure E-2: Truck Contribution to 2020 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) .................................. 3 

Figure E-3: Cost of Proposed Truck and Bus Regulation Down Substantially ........... 5 

Figure II-1: Truck Contribution to 2010 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) ................................ 20

Figure II-2: Truck Contribution to 2020 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) ................................ 20

Figure II-3: California Nonattainment Areas for PM2.5 ............................................ 21

Figure II-4: California Nonattainment Areas for Ozone ............................................ 22

Figure III-1: Example of Compliance with BACT Schedule....................................... 36

Figure III-2: Example of Compliance with the Phase-in Option................................. 37

Figure III-3: Example of a Fleet Utilizing Economic Relief Provision for Fleets that 

have Downsized .................................................................................... 38

Figure VI-1: Statewide Truck and Bus PM Emissions*.............................................. 46

Figure VI-2: Statewide Truck and Bus NOx Emissions*............................................ 47

Figure VI-3: Year by Year Comparison of Truck and Bus and Off-Road 

PM Emissions after Regulation is Applied: Current Rule Without 

Recession vs. Amended Rule with Recession....................................... 49

Figure VI-4: Year by Year Comparison of Truck and Bus and Off-Road NOx 

Emissions after Regulation is Applied: Current Rule Without 

Recession vs. Amended Rule with Recession....................................... 50

Figure VII-1: Cost of Proposed Truck and Bus Regulation Down Substantially ......... 57

Figure VII-2: Moving Company Annual Rule Costs vs. Normal Replacement Costs.. 59

Figure VII-3: Concrete Company Rule vs Normal Replacement Costs ...................... 60

Figure VII-4: Freight Company Annual Rule Costs vs. Normal Replacement Costs .. 61
-vi-
-viiAPPENDICES 

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

 B. Proposed Regulation Order for In-Use On-Road Diesel Fueled Heavy-Duty 

Drayage Trucks 

 C. Proposed Regulation Order for Tractor-Trailer Greenhouse Gas Emissions 

from Heavy-Duty Vehicles 

 D. Proposed Amendments to the Truck and Bus Regulation 

 E. Proposed Amendments to the Drayage Truck Regulation 

 F. Proposed Amendments to the Tractor-Trailer Greenhouse Gas Regulation 

 G. Emissions Analysis Methodology and Results 

 H. Public Outreach and Implementation 

 I. Costs and Cost Methodology 

 J. Health Impacts and Benefits and Methodology 

 
-viii-
-ixLIST OF ACRONYMS 

AB Assembly Bill 

ARB Air Resources Board 

ATCM Airborne Toxic Control Measure 

BACT Best Available Control Technology 

BC Black Carbon 

BOE Board of Equalization 

CAA Clean Air Act 

CCR California Code of Regulations 

CEQA California Environmental Quality Act 

CO2 Carbon Dioxide 

EJ Environmental Justice 

EPA Environmental Protection Agency 

GDP Gross Domestic Product 

GHG Greenhouse Gases 

GVWR Gross Vehicle Weight Rating 

GWP Global Warming Potential 

HP Horsepower 

HSC Health and Safety Code 

IFTA International Fuel Tax Agreement 

IPCC Intergovernmental Panel on Climate Change 

MMTCO2-e Million Metric Tons Carbon Dioxide-Equivalents 

NAAQS National Ambient Air Quality Standard 

NOx Oxides of Nitrogen 

PM Particulate Matter 

PM2.5 Particles up to 2.5 microns in diameter 

RD Research Department 

SIP State Implementation Plan 

TAC Toxic Air Contaminants 

TPD Tons per Day 

TRAC Truck Regulations Advisory Committee 

U.S. EPA United States Environmental Protection Agency 

VDECS Verified Diesel Emission Control Strategy 

VMT Vehicular Miles Traveled 
-x-
-1-

EXECUTIVE SUMMARY 

California faces many air quality challenges, whether they be meeting federal air quality 

standards, reducing premature mortality, addressing localized risk, or reducing 

greenhouse gas emissions. The Air Resources Board (ARB or Board) has put into 

place a series of comprehensive regulations and programs to meet these challenges. 

While nearly all diesel engines in the state are included in this program, trucks and 

buses represent the largest share of emissions and vehicles. As a result, California’s 

program targeting emission reductions from the nearly one million existing diesel trucks 

and buses that operate on California roads each year is arguably the most important 

component of ARB’s program to reduce emissions from diesel vehicles. These include 

the Truck and Bus regulation that reduces exhaust emissions from most heavy-duty 

diesel vehicles, the Drayage Truck regulation that reduces exhaust emissions from 

larger tractors that enter ports and intermodal rail yards and the Tractor-Trailer 

Greenhouse Gas regulation that reduces greenhouse gas emissions from long-haul 

tractor trailer combinations. This comprehensive program is intended to significantly 

reduce emissions from existing diesel vehicles throughout the state through a mix of 

exhaust and vehicle retrofits and vehicle turnover, so that by 2023, California has the 

cleanest, most efficient diesel fleet in the world. 

The need to reduce emissions from trucks continues to be significant. These vehicles 

are a major source of emissions. They contribute substantially to violations of the 

ambient air quality standards for both fine particulate matter (PM2.5) and ozone. They 

also contribute to localized health risk associated with exposure to diesel particulate 

matter and to premature deaths associated with exposure to ambient fine particulate 

matter in the air. 

California and the nation have been in an economic recession that was not anticipated 

when these diesel truck regulations were approved by the Board in 2007 and 2008. 

The recession has had a significant impact on companies that rely on diesel engines – 

whether it is trucking and transportation businesses, construction companies, or airlines. 

Overall, businesses’ revenues and employment are down, and this has reduced many 

fleets’ ability to make the investments needed to comply. 

While the current recession has been economically devastating to businesses 

throughout the state, it has also caused an overall reduction in both on-road and offroad diesel vehicle activity and emissions through reductions in the number of truck trips 

and vehicle miles traveled as well as in reductions in the number of pieces of 

construction equipment working on projects. Emissions are lower today because of the 

recession than what we had previously assumed. Reduced emissions have provided 

ARB an opportunity to go back and adjust the regulations targeting diesel trucks and 

buses to account for reduced emissions that are occurring from less business activity. 

Over the long term, the regulations are still critically important to ensuring that California 

meets both its short-term and long-term air quality obligations and health based goals. 
-2-

Considering this, in April 2010, the Board directed staff to update the emissions 

inventories from trucks and off-road equipment to reflect the impact of the recession on 

emissions. The Board further directed staff to develop amendments to the Truck and 

Bus and Off-Road diesel vehicle regulations that would provide economic relief to fleets 

while continuing to meet the Board’s air quality goals and obligations. The Board’s 

direction included the following principles for staff to consider in proposing amendments: 

• Continue progress toward cleaner air 

• Maintain public health benefits 

• Meet State Implementation (SIP) commitments 

• Provide incentives to achieve greenhouse gas reductions 

• Improve cost effectiveness 

• Lower peak year costs 

• Consider cumulative impact of both regulations 

• Provide most economic relief to fleets hardest hit by recession 

• Ensure emission reductions as economy recovers 

• Support clean technologies 

To support development of the proposed amendments, staff updated the emissions 

inventory for trucks to assess the impact of the economic recession on emissions and to 

integrate new information. Through staff’s assessment, it was determined that the 

recession has had a major impact on reducing emissions. Overall, 2010 truck and bus 

emissions are on average more than 20 percent lower because of the recession than 

we had estimated in 2008. 

A similar assessment was made for off-road vehicles and can be found in the Initial 

Statement of Reasons for Proposed Amendments to the Regulation for In-Use Off-Road 

Diesel-Fueled Fleets and Off-Road Large Spark Ignition Engine Fleet Requirements 

(ARB, 2010b). In that assessment, staff found that the recession has reduced activity 

and emissions in the construction sector by more than 50 percent. 

Despite these changes to the emissions inventories, heavy-duty trucks and buses 

continue to be the largest contributor to emissions in California, both in 2010 and 2020, 

as shown in Figure E-1 and Figure E-2. In addition, reducing emissions is necessary to 

reduce premature deaths associated with exposure to fine PM (PM2.5) and near-source 

exposure to diesel PM. 
-3-

Figure E-1: Truck Contribution to 2010 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) 

Off-Road Ag and 

Recreation

21% Off-Road Rule 

Scope

7%

Cars and Other 

On-Road

2%

Truck Rules 

Scope

40%

Locomotive

6%

Marine

24%

PM Emissions

Cars and Other 

On-Road

29% Truck Rules 

Scope

32%

Marine

11%

Locomotive

5%

Aircraft

3%

Off-Road Rule 

Scope

4%

Off-Road Ag and 

Recreation

16%

NOx Emissions

Figure E-2: Truck Contribution to 2020 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) 

Other Off-Road 

Ag and 

Recreation

15%

Off-Road Rule 

Scope

12%

Cars and Other 

On-Road

3%

Truck Rules 

Scope

40%

Locomotive

14%

Marine

16%

PM Emissions

Cars and Other 

On-Road

23%

Truck Rules 

Scope

22%

Off-Road Rule 

Scope

5%

Locomotive

10%

Aircraft

6%

Marine

19%

Other Off-Road 

Ag and 

Recreation

15%

NOx Emissions

The SIP is California’s roadmap towards achieving federal clean air standards by the 

applicable deadlines. To assess progress towards meeting the emission reduction 

obligations in the SIP, staff evaluated how much lower emissions would be from the 

revised inventory and the recession than were anticipated at the time the regulations 

were adopted. Any excess emission reductions achieved are referred to as an emission 

margin. The margin defines how much economic relief could be provided under the 

regulations while still meeting the legal emission reduction requirements of the SIP. To 

allow for a comparison of different pollutants (PM and NOx), the margin is calculated, by 

air basin, in NOx equivalent emissions. Table E-1 shows the emission margin for the 

South Coast and San Joaquin Valley air basin for 2014, which is the attainment date for 

these two air basins to meet federal PM2.5 standards. Based on this analysis, it is 

feasible to significantly reduce the economic impact on affected fleets while meeting SIP 

obligations. 
-4-

Table E-1: Emissions Are Less Than the 2014 SIP Target 

Existing Truck and Off-Road Regulations, Including Recession 

Air Basin 

Equivalent Tons of NOx 

Below Combined SIP 

Target 

South Coast 62 

San Joaquin Valley 40 

The U.S. EPA has recently concluded, based on the published and peer reviewed 

scientific literature, that long-term exposure to PM2.5 is causally associated with 

premature mortality. A causal relationship means it has the highest scientific level of 

certainty. The U.S. EPA also found that premature deaths caused by PM2.5 occur at 

levels well below the Federal air quality standard for PM2.5. The U.S. EPA estimates 

that about 63,000 to 80,000 premature deaths each year in the U.S. are related to 

PM2.5. ARB staff used the EPA methodology to estimate that long-term exposure to 

PM2.5 from all sources in California results in 9,200 premature deaths annually and that 

reducing emissions to meet the Federal standard would reduce premature deaths by 

2,700 annually. Reducing PM emissions below the Federal standard would reduce the 

number of premature deaths even further. 

After holding three workshops about the Truck and Bus regulation, one focused on 

school bus requirements, and 16 statewide workshops to discuss proposed 

amendments in conjunction with amendments to the Off-Road regulation in 2010, staff 

has developed a comprehensive set of amendments covering both regulations that 

would: 

• Provide economic relief for affected on-road and off-road fleets while 

substantially reducing compliance costs; 

• Achieve the emissions reductions needed to meet SIP commitments to attain 

federal air quality standards; 

• Continue to reduce localized risk, and; 

• Continue to reduce the impacts of diesel emissions on premature mortality. 

The proposed amendments to the Truck and Bus regulation would exempt about 

150,000 lighter trucks with a gross vehicle weight rating less than 26,001 pounds (most 

of which are operated exclusively in California) from having to meet the PM filter 

requirements. Instead, beginning in 2015, these lighter trucks would be required to be 

modernized (replaced), but not until the trucks are 20 years old or older. 

For larger, heavier trucks with 1998 to 2006 model year engines, the requirements 

would be changed such that these trucks would only be required to have PM filters 

installed from 2012 to 2014. They would then be able to operate at least another 

8 years (instead of 4 years, as provided with the current regulation) before needing to 

be replaced with a truck meeting the 2010 model year emissions standard or be retrofit 
-5-

to have equivalent emissions. The remaining heavier trucks with 1997 and older 

engines would be replaced when 20 years old or older starting in 2015. 

Overall, by 2023 all trucks all trucks operating in California would need to have 2010 

model year or newer engines, or equivalent emissions. The proposed amendments 

also simplify the regulation while retaining flexibility for fleets to determine which 

vehicles to retrofit or modernize. The regulation would continue to have provisions, 

such as reduced fleet size credits that would now expire in 2016 rather than in 2014 

under the current regulation, which should reduce the annual compliance requirements 

for fleets most affected by the recession. For example, if a fleet has 20 percent fewer 

trucks operating than it did in 2006, then no action would be required for 20 percent of 

its remaining trucks until 2016. A fleet that has 40 percent fewer trucks would have no 

action required for 40 percent of its remaining trucks until 2016. The regulation also 

continues to provide incentives for the early retrofit of existing trucks in order to achieve 

early emission reductions. 

The Drayage Truck regulation would eliminate the 2014 requirement to modernize all 

trucks visiting ports or intermodal rail yards to 2007 model year engines or newer, and 

would instead align this requirement with the Truck and Bus regulation. Drayage trucks 

with PM filters would now comply until 2020 rather than having to upgrade the truck 

again by 2014. The proposed amendments would also include changes to prevent 

trucks from circumventing the regulation by exchanging drayage cargo with dirty trucks 

outside the port or rail facilities, a practice commonly known as “dray-off.” 

The proposed amendments to the Tractor-Trailer GHG regulation would provide fleets a 

new option to begin the phase-in of the trailer retrofit requirements by extending the 

reporting period another year, extend the deadline for using low rolling resistance tires 

for existing trucks and trailers and would make other changes that provide more 

flexibility for fleets to comply. The Tractor-Trailer GHG regulation currently allows 

owners of large fleets of 2010 and previous model year trailers to phase-in compliance 

from 2010 through 2015. In order to participate in this large fleet compliance schedule, 

an owner was required to submit to ARB a compliance plan by July 1, 2010. The 

proposed amendment would establish a second large fleet compliance schedule 

allowing owners of these trailers to phase-in compliance from 2011 through 2015. To 

participate in this second phase-in schedule an owner would be required to submit a 

compliance plan by July 1, 2011. The proposed amendments would delay the low 

rolling resistance tires requirements for 2010 and previous model year trailers from 

January 1, 2011 to January 1, 2017. In addition, the compliance date for retrofitting 

2010 and previous model year tractors with low rolling resistance tires would be 

extended from January 1, 2012 to January 1, 2013. 

The proposed amendments to the Truck and Bus regulation would provide substantial 

economic relief to all affected fleets. The proposed amendments would eliminate the 

PM filter requirements for lighter trucks and, for the next decade, would only require 

modernization of engines that are 20 years old or older. 
-6-

Overall, the estimated compliance costs of the Truck and Bus regulation over the next 

five years would be reduced by 50 percent and would be reduced by about 60 percent 

over the life of the regulation. Figure E-3 shows how the average costs of the regulation 

would decline compared to the original estimates for the current regulation. 

Figure E-3: Cost of Proposed Truck and Bus Regulation Down Substantially

$0.0

$1.0

$2.0

$3.0

$4.0

$5.0

$6.0

Cost (Billions)

First 5 Years Total Regulation

Proposed

Existing

Similarly, aligning the requirements of the Drayage Truck regulation with the proposed 

amendments to the Truck and Bus regulation would lower costs for drayage truck 

operators by extending the useful life of their already retrofitted trucks an additional six 

years and by eliminating the requirement to modernize to a truck with a 2007 model 

year engine or newer by 2014. 

Parallel amendments to the Tractor-Trailer GHG regulation would improve compliance 

flexibility and would not result in significant changes in compliance costs. 

Overall, the regulations would continue to provide significant emissions reductions that 

are necessary to meet California’s air quality obligations and goals. The proposed 

amendments would reduce the emissions margin to zero in the San Joaquin Valley and 

to 5 tons/day in the South Coast. Because the combined margin for trucks and buses 

and off-road equipment is minimized, maximum relief is provided while still meeting SIP 

legal obligations. 

In addition, the truck regulations would continue to provide significant health benefits by 

reducing premature mortality from PM2.5 exposure and localized risk from diesel PM. 

Staff estimates that 3,500 premature deaths (2,700 to 4,400 with a 95 percent 
-7-

confidence interval) would be avoided by implementation of the amended truck 

regulations from 2010 to 2025. This estimate is based on United States Environmental 

Protection Agency’s (U.S. EPA) new risk assessment methodology (U.S. EPA, 2010), 

and includes the most recent air quality data available (2006 to 2008) and the latest 

emissions inventory estimates. Staff also expects localized risk to be reduced 

commensurate with the expected diesel particulate matter (PM) emission reductions. 
-8-
-9-

I. INTRODUCTION 

This Staff Report: Initial Statement of Reasons (Staff Report) supports the proposed 

amendments to the following regulations: 

• Regulation to Reduce Emissions of Diesel Particulate Matter, Oxides of Nitrogen 

and Other Criteria Pollutants, from In-Use Heavy-Duty Diesel-Fueled Vehicles. 

(Truck and Bus regulation), title 13, California Code of Regulations (Cal. Code 

Regs.), section 2025; 

• Regulation for In-Use On-Road Diesel-Fueled Heavy-Duty Drayage Trucks (Drayage 

Truck regulation), title 13, Cal. Code Regs., section 2027; and 

• The Heavy-Duty Vehicle Greenhouse Gas (GHG) Emission Reduction Measure, 

(Tractor-Trailer GHG regulation), title 17, Cal. Code Regs., sections 95301 to 95307, 

95309, and 95311. 

The Staff Report describes the proposed amendments and the rationale for each 

amendment. It also presents staff’s analysis of impacts associated with the 

implementation of the proposed amendments, including costs, and economic and 

environmental impacts. The proposed text of each regulation and appendices with 

supplementary information are addenda to the staff report. The text of the regulations is 

set forth in the proposed regulation orders in Appendix A for the Truck and Bus 

regulation, Appendix B for the Drayage Truck regulation, and Appendix C for the 

Tractor-Trailer GHG regulation. 

A. Background 

The Truck and Bus regulation was approved by the Air Resources Board (ARB or 

Board) on December 12, 2008, to reduce emissions of diesel particulate matter (PM), 

oxides of nitrogen (NOx), and other criteria pollutants from about one million in-use 

diesel trucks and buses that operate in California. The regulation became effective in 

January 2010 and requires trucks and buses to meet PM filter requirements starting 

January 1, 2011, and NOx reduction requirements starting January 1, 2013. The 

emissions reductions will be achieved through the installation of verified diesel emission 

control strategies (VDECS1

 or PM filter) on existing engines, by replacing vehicles with 

newer ones having cleaner engines or repowering vehicles with newer, cleaner engines. 

The reductions are necessary to meet State and federal air quality standards, to reduce 

premature deaths attributable to exposure to fine particulate matter (PM2.5) emissions 

and to reduce exposure to diesel PM in support of the Diesel Risk Reduction Plan 

adopted by the Board on September 30, 2000 (ARB, 2000). 

The Drayage Truck regulation, approved by the Board In December 2007, reduces 

emissions from diesel-fueled drayage trucks, which are used to transport containers, 

 

1

 A retrofit device that has been verified under ARB’s Verification Procedure, Warranty and InUse Compliance Requirements for In-Use Strategies to Control Emissions from Diesel 

Engines, title 13, CCR, sections 2700 et seq. 
-10-

bulk, and break-bulk goods to and from ports and intermodal rail yards. The regulation 

became effective in December of 2008, by requiring drayage trucks to meet emission 

requirement beginning January 1, 2010. 

The existing Tractor-Trailer GHG regulation was approved by the Board on 

December 12, 2008. The purpose of this regulation is to reduce GHG emissions from 

new and existing 53-foot or longer box-type trailers and the tractors that haul such 

trailers by requiring them to utilize technologies that would result in improved fuel 

efficiency, such as low rolling resistance tires and aerodynamic technologies such as 

side skirts, gap fairings, and rear trailer fairings. The regulation became effective and 

enforceable beginning January 1, 2010. The Tractor-Trailer GHG regulation is one of 

the measures identified in ARB’s Scoping Plan (ARB, 2008a) to reduce GHG emissions 

and contributes towards meeting the GHG emission reduction goals of Assembly Bill 32 

– the Global Warming Solutions Act of 2006 (AB 32) (Núñez, 2006). 

B. Regulatory Authority 

1. Truck and Bus and Drayage Truck Regulations 

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), 

39601 (Standards, Definitions, Rules and Measures), and 39602.5 (Adoption of Rules 

and Regulations) 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 

and to attain federal national ambient air quality standards in all areas by applicable 

attainment dates. 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 new and in-use on-road and off-road diesel engines used in 

motor vehicles. 

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. 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. 

Section 209(a) of the federal Clean Air Act (CAA) preempts states from adopting 

emission standards for new motor vehicles and engines. However, section CAA 209(b) 

provides that the Administrator of the U.S. Environmental Protection Agency (U.S. EPA) 

shall grant California a waiver of preemption, unless the administrator can make certain 
-11-

specified findings. Neither the adopted regulations nor the proposed amendments 

establish emission standards for new motor vehicles and engines, and thus no issue of 

federal preemption exists. Additionally, U.S. EPA does not have authority to adopt inuse regulations for motor vehicles, and thus there are no federal regulations 

comparable to the Truck and Bus, Tractor-Trailer GHG, and Drayage Truck regulations. 

CAA section 209(e)(2) allows California, upon obtaining authorization from U.S. EPA, to 

adopt and enforce emission standards and other requirements related to the control of 

emissions for new and in-use off-road engines not expressly preempted (i.e., as set 

forth in CAA section 209(e)(1), new off-road engines under 175 hp used in farm and 

construction equipment and vehicles and new locomotives and locomotive engines). 

The Truck and Bus regulation has requirements for off-road engines used in yard-goats 

and two engine street sweepers, and to the extent that the amended regulation and 

amendments to other existing ARB off-road regulations require authorization, ARB will 

request that U.S. EPA grant such authorization. U.S. EPA does not have authority to 

adopt in-use regulations for off-road engines, and thus there are no federal regulations 

comparable to the California adopted regulatory provisions affecting off-road engines 

used in two engine street sweepers and yard goats. 

2. Tractor-Trailer GHG Regulation 

In 2006, AB 32 was signed into law, creating a comprehensive, multi-year program to 

reduce GHG emissions in California (Núñez, 2006). It calls for the reduction of GHG 

emissions to 1990 levels by the year 2020, a reduction of about 25 percent. In addition, 

the Governor issued an Executive Order directing the establishment of state GHG 

targets to reduce GHG emissions to 80 percent below 1990 levels by 2050. The 2020 

goal establishes an aggressive, but achievable, mid-term target, while the 2050 goal 

represents the level the scientific community believes must be reached in order to 

stabilize the climate. 

To swiftly address GHG reductions in the near-term, one requirement of AB 32 directed 

ARB to identify a list of early action measures that could be adopted by the Board by 

January 1, 2011. In 2007, the Board identified 44 such early action measures including 

potential regulations affecting motor vehicles, fuels, refrigerant in cars, and many other 

sources, including nine “discrete” early action measures, which would be adopted and 

enforceable by January 1, 2010 (ARB, 2007). The Tractor-Trailer GHG regulation is 

one of these discrete early action measures. 

C. Rationale for the Proposed Amendments 

The Truck and Bus regulation was approved on December 12, 2008 via Resolution 

08-43, in which the Board directed staff to provide informational updates at Board 

meetings in January 2009 and December 2009. At the December 2009 meeting, staff 

reported on the impact of the recession on emissions and the vehicles affected by the 

regulation. Based on staff’s analysis showing that vehicle activity and emissions are 

both below the levels estimated when the regulation was developed, the Board 

determined that additional flexibility could be provided for fleets adversely affected by 
-12-

the economy, and directed staff to propose amendments to the regulation that take into 

account the impacts of the economy on emissions and affected vehicles. 

In April 2010, the Board directed staff to update the emissions inventories from on-road 

heavy-duty vehicles and off-road equipment to reflect the impact of the recession on 

emissions. The Board further directed staff to develop amendments to the Truck and 

Bus and Off-Road diesel regulations together that would provide economic relief to both 

on-road and off-road fleets while continuing to meet the Board’s air quality goals and 

obligations. The Board’s direction included the following principles (Table I-1) for staff 

to consider in proposing amendments: 

Table I-1: Ten Guiding Principles 

1. Continue progress toward cleaner air 

2. Maintain public health benefits 

3. Meet SIP commitments 

4. Incentivize greenhouse gas reductions 

5. Improve cost effectiveness 

6. Lower peak year costs 

7. Consider cumulative impact of both regulations 

8. Provide most relief to fleets hardest hit by recession 

9. Ensure emission reductions as economy recovers 

10. Support clean technologies 

The Board’s directives have prompted the proposed amendments discussed in this Staff 

Report. 

Staff’s proposed amendments meet these guidelines by making substantial 

amendments to provide economic relief to fleets while assuring that emissions benefits 

are preserved. The proposed amendments to the Truck and Bus regulation would 

exempt about 150,000 lighter trucks with a gross vehicle weight rating less than 

26,001 pounds (most of which are operated exclusively in California) from having to 

meet the PM filter requirements. PM filters include filters that are part of the 

manufacturers’ original equipment and those that are installed afterwards (PM retrofit). 

The amendments would not replace any truck less than 20 years old (about 97 percent 

of trucks) until 2020 and would extend the use of a PM retrofit from four years to 

eight years before any modernization requirements would apply. By 2023 all trucks 

would still need to have a 2010 or newer engine or equivalent. The proposed 

amendments would also substantially simplify the regulation while retaining flexibility for 

fleets to determine which vehicles to retrofit or modernize. The regulation would 

continue to have provisions, such as reduced fleet size credits, that would reduce the 

annual compliance requirements for fleets most affected by the recession and offer 

incentives for fleets to take early compliance action. 

Staff is proposing several amendments to the Drayage Truck regulation to align the 

requirements with the proposed amendments to the Truck and Bus regulation. The 
-13-

goals of the changes are to provide economic relief to drayage truck owners and to 

prevent drayage trucks from exchanging cargo with dirty trucks near port or rail facilities 

commonly known as “dray off”. The changes would also ensure PM exposure reduction 

goals for communities located near port and rail yards continue to be met. 

Staff is proposing to amend the Tractor-Trailer GHG regulation to provide affected fleets 

with additional flexibility in meeting the requirements with minimal impact on the GHG 

benefits as initially approved. 

D. Stakeholder Participation 

Staff conducted a number of statewide workshops and meetings to solicit comments 

from affected stakeholders regarding the proposed amendments to the Truck and Bus, 

Tractor-Trailer GHG, and Drayage Truck regulations, and to discuss updates to the 

emissions inventories and other information. These efforts are described further below. 

1. Public Workshops 

Since January 2010, staff held 19 public workshops statewide to discuss proposed 

amendments to the three regulations and changes to the emission inventories. In 

addition, one workshop was held that focused only on the school bus requirements of 

the Truck and Bus regulation. For the workshops held in Central Valley, live video feed 

was also provided to locations in Modesto and Bakersfield. The August 31 to 

September 8, 2010 workshop series also provided stakeholders an opportunity to 

discuss the revised report, “Estimate of premature deaths associated with fine particle 

pollution (PM2.5) in California using a U.S. Environmental Protection Agency 

Methodology,” which was released by ARB on August 31, 2010 (ARB, 2010a). Table 

I-2 shows the dates, locations, and the primary discussion topics of the workshops. 
-14-

Table I-2: Public Workshop Dates and Locations 

Workshop Dates Locations 

Truck and 

Bus 

Drayage 

Truck

Emissions 

Inventory 

Tractor 

Trailer GHG 

January 20, 2010 El Monte X 

January 25, 2010 Sacramento (webcast) X 

January 26, 2010 Central Valley X 

May 6, 2010 Sacramento (webcast) X X 

May 12, 2010 El Monte X X 

May 18, 2010 Central Valley X X 

June 23, 2010 Central Valley X X 

June 28, 2010 Sacramento (webcast) X X 

July 1, 2010 El Monte X X 

July 6, 2010 San Diego X X 

July 28, 2010 Sacramento X* 

August 31, 2010 El Monte X** 

September 1, 2010* San Diego X** 

September 3, 2010* Central Valley X** 

September 7, 2010* Sacramento (webcast) X** 

September 8, 2010* Oakland X** 

September 30, 2010 Sacramento (webcast) X X X 

October 4, 2010 El Monte X X X 

October 5, 2010 San Diego X X X 

October 12, 2010 Central Valley X X X 

* Discussed only school bus provisions 

** PM2.5 Mortality Report (ARB, 2010a) was discussed 

2. Other Meetings 

In addition to the workshops noted above, staff also met with a number of companies 

and association representatives about proposed amendments and emission inventory 

changes for the Truck and Bus regulation and the Drayage Truck regulations. Staff met 

with individuals and representatives of the following industries: 

• street-sweepers, 

• motor coaches and buses, 

• log trucks, 

• construction, 

• agriculture, 

• environmental organizations, 

• trucking associations, 

• school district representatives, 
-15-

• school transportation associations, and 

• ports, harbors, and marine interests. 

Staff also held meetings to discuss the proposed amendments to the Tractor-Trailer 

GHG regulation with representatives from the following interests: 

• tire industry representatives, 

• aerodynamic equipment manufacturers, 

• trailer manufacturers, 

• trucking associations (including Canada), 

• individual fleets, 

• Cascade Sierra Solutions, 

• Rubber Manufacturers Association, and 

• U.S. EPA Smartway program. 

A more complete list of specific companies and associations with which staff met is 

provided in Appendix H. 

3. Outreach Efforts 

Staff is implementing a comprehensive outreach plan to assist and educate fleets on 

actions needed to comply with the regulations, and the financial incentive programs that 

are available. The plan includes developing outreach activities with input from industry 

representatives, distributing information through dealers and other state and local 

agencies, conducting training seminars and presentations throughout the State, along 

with communicating through traditional media and utilizing e-mail listservers. Staff will 

continue the successful implementation of the TruckStop website and the toll free phone 

number, 866-6DIESEL. These tools allow fleets to get information and answers to their 

questions directly regarding a variety of regulations that affect trucks. Staff formed the 

Truck Regulations Advisory Committee (TRAC) to facilitate communication with affected 

stakeholders and obtain feedback on the implementation of the regulations. 

Subcommittees were also formed to address issues that affect outreach, small 

businesses, reporting, and specific source category implementation issues. ARB staff 

established informational networks used by vehicle and equipment dealers, local air 

districts, and state agencies such as the Department of Motor Vehicles and the 

California Highway Patrol to distribute informational materials about the regulations. In 

addition, since the beginning of 2009, staff has provided training and presentations on 

the requirements of the regulations at more than 200 events, as outlined in Appendix H. 

After the Board meeting, staff will continue its outreach efforts with an updated plan to 

inform fleets about any regulatory changes. Staff will also inform fleets of any new or 

expanded incentive funding opportunities the proposed amendments might provide. 

Education efforts will include training seminars, public workshops, and individual 

meetings with stakeholders throughout the State and continuation of the 866-6DIESEL 

toll free phone number. Staff will also continue to work with industry representatives 

and associations on additional ways to educate varied stakeholders on the amendments 

to the regulations through TRAC. 
-16-
-17-

II. NEED FOR EMISSIONS REDUCTIONS 

This chapter discusses the emission impacts of trucks and buses in California, and the 

continued need to reduce emissions in order to reduce the health impacts of these 

emissions. 

There are nearly one million trucks and buses that travel California’s highways each 

year. Of these, about 400,000 are registered and operated exclusively in California, 

with the balance of these out-of-sate trucks that annually frequent California. 

Today and into the future, these vehicles remain the largest contributor of emissions 

from all mobile sources, and they contribute substantially to violations of the ambient air 

quality standards for both PM2.5 and ozone, to localized health risk associated with 

exposure to diesel PM, and to premature deaths associated with exposure to PM2.5. 

For this reason, the emission reductions anticipated from the Truck and Bus regulation 

remain important to reduce the public health impacts from truck and bus emissions. 

A. Updates to Truck Emissions Inventory 

During development of the Truck and Bus regulation in 2006-2008, staff conducted a 

comprehensive re-evaluation of the heavy duty diesel truck and bus emissions 

inventory, which led to a revised analysis of emissions on a statewide basis. Revised 

emissions estimates were calculated using a database that embedded methodologies 

derived from ARB’s then existing on-road emissions model, EMFAC2007, and 

integrated new data and assumptions into an emissions database. The revised 

calculation approach accounted for different categories of trucks and buses which were 

differentiated based on their age, travel characteristics, registration type, registration 

status, and vocation. 

In December 2008, the National Bureau of Economic Research declared that the United 

States had entered an economic recession and as a result, the staff began to assess 

the impacts of the recession on emissions from trucks and buses. Staff’s results 

suggested that emissions in 2009 across all trucks and buses operating in California 

were approximately 20 percent lower (ARB, 2009a) than estimates provided in the 

technical support document for the 2008 rulemaking (ARB, 2008b). 

Over the past year staff has continued to make improvements to the emissions analysis 

to reflect the recession and new data. Updates to the inventory included refinements to 

the assessment of the impact of the recession on emissions, development of regional 

emissions estimates, revisions to the number of miles traveled in California by nonCalifornia registered vehicles, addition of new vehicle categories, and improved lifetime 

mileage assumptions. Staff also received a request from Sierra Research to reduce 

lifetime mileage assumptions even further beyond the changes made already to the 

inventory, and to reduce mileage accrual assumptions for older vehicles. After 

reviewing the information submitted by Sierra Research, staff found their data 
-18-

insufficient to support the requested changes. As a result, staff did not include the 

requested changes in the final inventory. 

1. Impact of the Recession on Emissions 

The 2008 rulemaking emissions forecasts for the Truck and Bus regulation were 

designed to focus on longer-term trends in emissions and not on the impact of the 

economic cycle on emissions. Since 2008, California and the nation have been 

impacted by a major economic recession that has significantly reduced on-road diesel 

fuel use due to reduced demand for trucking and bus services, and significantly reduced 

new vehicle sales, whose impact will affect the truck and bus fleet age profiles into the 

future. Because of these two factors, staff developed revised activity growth and age 

profile assumptions for each calendar year in the inventory. 

Staff evaluated fuel usage, employment, new vehicle sales and other economic 

surrogates to assess the impact of the recession on emissions. The recession has led 

to a 25 percent reduction in overall trucking activity in California in 2009 from what was 

previously estimated for the 2008 Rulemaking. Staff evaluated economic forecasts to 

assess a range of possible trucking activity recovery scenarios. No economic analyses 

forecast California-specific on-road diesel fuel use or emissions into the future. As a 

result, staff developed two possible truck activity and sales growth scenarios for coming 

out of the recession. The faster recovery scenario assumed the economy would 

rebound and return to previously forecasted activity in 2017. The second slower 

recovery scenario assumed previous economic levels would not be reached until 2023 

or later. Staff considered the possibility of assuming the slower recovery scenario, but 

determined that would be inappropriate. The slower recovery scenario was designed to 

be a worst-case estimate of longer term emissions growth trends. Rather than rely on 

either the slower or faster recovery scenarios, staff assumed a middle case between the 

two forecasts. 

2. Development of Regional Emissions Estimates 

Staff developed a new procedure for allocating statewide emissions to each air basin in 

California so the impact of the regulation could be evaluated regionally. This is a major 

improvement from the previous analysis in which only statewide emissions estimates 

from the revised analysis were available, and is based upon extensive staff data 

collection and analysis. 

3. Revisions to Annual Mileage Estimates for Non-California Registered 

Trucks 

The 2008 inventory analysis assumed a set amount of vehicle miles traveled by 

out-of-state trucks in California in 2005, based on information provided from the State 

Board of Equalization (BOE) International Fuel Tax Agreement (IFTA) program. Staff 

received updated information after the 2008 rulemaking in 2009 and 2010 that 

suggested out-of-state truck mileage estimates should be lower than were previously 

assumed. Staff revised the estimates lower; the incorporation of this new data reduced 
-19-

out-of-state truck vehicles miles traveled (VMT) in California by 28 percent from 

previous estimates. 

4. Addition of New Vehicle Categories 

In order to reflect the impact of the recession and selected regulatory provisions, staff 

developed new inventory categories reflecting construction trucks, motorcoaches, and 

divided the medium-heavy duty diesel truck and bus categories into two categories – 

one each above and below 26,000 pounds gross vehicle weight rating (GVWR). 

5. Modification of Lifetime Mileage Assumptions 

Truck emission rates are a function of cumulative mileage on the vehicle - an emissions 

process called deterioration. The cumulative mileage estimated on the vehicle can be 

measured with the vehicle odometer. Our previous analyses assumed that the 

odometer reading is the sum of estimated year by year mileage accrual. However, staff 

evaluated this assumption using several data sources and found that older vehicles did 

not have nearly as high an odometer reading as would be predicted by that assumption. 

Staff evaluated several different data sources and found that medium-heavy duty diesel 

truck odometer readings tended, on average, to not increase with age above 

400,000 miles. Staff found that heavy heavy-duty diesel truck odometer readings 

tended not to increase with age above 800,000 miles. As a result, staff capped 

modeled odometer values at those levels, which reduced emission rates for older 

vehicles. This change reduced baseline emissions by a few percent, and had a minimal 

impact on the inventory after the regulation was applied. 

Changes to emissions inputs independent of the recession, including out-of-state VMT 

estimates and lifetime mileage assumptions reduced baseline emissions by about 

10 percent from what was assumed in 2008. The recession has reduced emissions by 

an additional 25 percent in 2009 and 2010, an additional 7 percent in 2014, and 

10 percent in 2020 from what was assumed in 2008. Overall, emissions are 35 percent 

lower in 2010, 17 percent lower in 2014, and 20 percent lower in 2020 than was 

anticipated in the 2008 Rulemaking. 

B. Current and Future Emissions 

As can be seen below in Figure II-1, in 2010, even after considering the impacts of the 

recession, emissions from trucks that are subject to both the Truck and Bus regulation 

and Drayage Truck regulation are the single largest statewide contributor to mobile 

source emissions, representing 40 percent of PM emissions, and also contribute over 

30 percent of NOx emitted from all mobile sources in California, including cars. Both 

NOx and PM contribute to ambient PM2.5 concentration, and NOx is also a precursor to 

ozone. In Figure II-1 and Figure II-2, the vehicles within the scope of the Truck and Bus 

regulation and Drayage Truck regulations are labeled “Truck Rules Scope.” 
-20-

Figure II-1: Truck Contribution to 2010 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) 

Off-Road Ag and 

Recreation

21% Off-Road Rule 

Scope

7%

Cars and Other 

On-Road

2%

Truck Rules 

Scope

40%

Locomotive

6%

Marine

24%

PM Emissions

Cars and Other 

On-Road

29% Truck Rules 

Scope

32%

Marine

11%

Locomotive

5%

Aircraft

3% Off-Road Rule 

Scope

4%

Off-Road Ag and 

Recreation

16%

NOx Emissions

Without the truck regulations, in 2020 the emission impact of trucks within the scope of 

the truck regulations would remain significant. As can be seen in Figure II-2 below, 

trucks would continue to be the single largest statewide mobile source contributor to PM 

emissions, and would contribute nearly a quarter of the NOx emitted from all mobile 

sources including cars in California. 

Figure II-2: Truck Contribution to 2020 Statewide Mobile Source Emissions 

(Particulate Matter and NOx Without Regulations) 

Off-Road Ag 

and Recreation

15%

Off-Road Rule 

Scope

12%

Cars and Other 

On-Road

3%

Truck Rules 

Scope

40%

Locomotive

14%

Marine

16%

PM Emissions

Cars and Other 

On-Road

23%

Truck Rules 

Scope

22%

Off-Road Rule 

Scope

5%

Locomotive

10%

Aircraft

6%

Marine

19%

Off-Road Ag and 

Recreation

15%

NOx Emissions

Today these vehicles are significant contributors to exceedances of federal ambient air 

quality standards, and because these vehicles are expected to remain a significant 

contributor to overall emissions, they will also continue to contribute substantially to 

continue to violations into the future. Uncontrolled, they will also continue to contribute 
-21-

to the localized health risk associated with exposure to diesel PM and to premature 

deaths associated with exposure to ambient PM2.5. 

C. Meeting Air Quality Standards 

1. National Ambient Air Quality Standards 

The U.S. EPA has established health protective National Ambient Air Quality Standards 

(NAAQS) for a number of criteria pollutants, including PM2.5 and ozone. States with 

areas that do not meet these standards must develop SIPs and adopt regulations to 

meet the standards by certain deadlines. Figure II-3 and Figure II-4 below show the 

nonattainment areas in California for PM and Ozone, respectively. Two air basins in 

California in particular – the South Coast Air Basin and the San Joaquin Valley Air Basin 

– are in nonattainment for both PM2.5 and the 8-hour ozone standard. 

Figure II-3: California Nonattainment Areas for PM2.5 

Attainment

Unclassified

Nonattainment
-22-

Figure II-4: California Nonattainment Areas for Ozone 

In September 2007, ARB approved a SIP committing the State to develop measures to 

achieve emission reductions from sources under State regulatory authority and attain 

the NAAQS in these areas.2 These air basins are both required to attain the PM2.5 

standard by 2014, and the 8-hour ozone standard by 2023. A, key strategy towards 

meeting these standards is significantly reducing emissions from existing trucks and 

buses operating in California. 

Overall, to meet the PM2.5 standard in the South Coast and the San Joaquin Valley Air 

Basins, NOx emissions must be reduced by approximately 50 percent. Even greater 

reductions of NOx, on the order of 75 to 88 percent, will be needed to achieve the 

8-hour ozone standard in the by 2023. Despite the fact that emissions in future years 

are expected to be lower than originally anticipated when the regulations were adopted, 

substantial emissions reductions from trucks and buses are still needed by 2014 to 

meet the PM2.5 attainment deadline and by 2023 to meet the 8-hour ozone attainment 

deadline. 

2. Meeting SIP Targets 

In directing staff to propose changes to the Truck and Bus and Off-Road regulations 

together, the Board directed staff to also consider the impact of the recession and 

inventory changes on fleets affected by these regulations in deciding how to provide 

appropriate economic relief. This was intended to ensure emissions reductions could 

 

2

 Additional discussion of the SIP is addressed in the 2008 Technical Support Document 

(ARB, 2008). 

Nonattainment Unclassified/Attainment
-23-

be targeted most cost effectively, and the combined emissions benefits achieved by the 

two rules would continue to meet SIP requirements. 

To assess progress towards meeting the emission reduction obligations in the SIP, staff 

evaluated whether the lower emissions from the revised inventories for both trucks and 

off-road vehicles, combined with the effects of the recession, provided greater emission 

reductions than were expected. Any excess emission reductions achieved are referred 

to as an emission margin. The margin defines how much economic relief can be 

provided under the regulations while still meeting the legal emission reduction 

requirements of the SIP. 

To allow for a comparison of different pollutants (PM and NOx), the margin is 

calculated, by air basin, in NOx equivalent emissions, since both pollutants contribute to 

ambient levels of PM2.5 in the atmosphere. Table II-1 below shows the emission 

margin for the South Coast and San Joaquin Valley Air Basins for 2014, which is the 

attainment date for these two air basins to meet federal PM2.5 standards. As can be 

seen, based on this analysis, it is feasible to provide economic relief to affected fleets 

while still meeting all SIP obligations, so long as these emission margins are not 

exceeded. 

Table II-1: Emissions Are Less than the 2014 SIP Target – Existing 

Truck and Off-Road Regulations, Including Recession

Air Basin 

Equivalent Tons of NOx 

Below Combined SIP 

Target 

South Coast 62 

San Joaquin Valley 40 

D. PM Emissions and Mortality 

The U.S. EPA recently published a review of the PM-related health science literature in 

the Integrated Science Assessment, which is the first part of the ongoing review of the 

national ambient air quality standards for PM (U.S. EPA, 2009). Based on the overall 

evidence from the more than one thousand peer-reviewed publications of PM2.5 

exposure in humans, animals, and cells, the U.S. EPA concluded that long-term 

exposure to PM2.5 exposure is causally associated with premature mortality, and that 

premature deaths caused by PM2.5 occur at levels as low as 5.8 micrograms per cubic 

meter, which is considerably lower than the current national standard of 15 micrograms 

per cubic meter. A causal relationship means it has the highest scientific level of 

certainty in its ability to contribute to premature death. This report was peer reviewed 

through a public process by the Clean Air Scientific Advisory Committee Particulate 

Matter Review Panel, an independent body of 24 national scientists. 

The U.S. EPA risk assessment methodology, the basis for ARB’s calculation, was 

developed to estimate premature deaths associated with PM2.5 exposure across the 
-24-

nation. This report was also peer reviewed through a public process by the Clean Air 

Scientific Advisory Committee Particulate Matter Review Panel. The relationship 

between premature death and PM2.5 relies on a new comprehensive study of about 

500,000 participants in 116 U.S. cities (Krewski et al., 2009). Besides the large 

representative study population, the U.S. EPA concluded this study has significant 

advantages over other epidemiological studies of the relationship between PM2.5 and 

premature death. These include the use of more recent measured PM2.5 air quality 

data, more individual lifestyle information to allow for consideration of potential 

confounding (compared to other cohort studies), and rigorous statistical methods. 

Using this relationship, the U.S. EPA conducted a national-scale analysis and a more 

limited risk assessment, which was focused on 15 urban study areas, including Fresno 

and Los Angeles (U.S. EPA, 2010). 

Based on this work, the U.S. EPA estimates that about 63,000 to 80,000 premature 

deaths each year in the United States are related to PM2.5. Using the same 

methodology, ARB staff estimated that 9,200 (7,300 to 11,000, 95 percent confidence 

interval) of these deaths occur annually in California and that reducing emissions to 

meet the Federal standard would result in 2,700 fewer premature deaths annually. 

Reducing PM emissions further would provide an additional reduction in the number of 

premature deaths. 

E. Exposure to Localized Diesel PM Emissions 

Diesel PM as a component of ambient PM2.5 is a significant public health concern 

throughout the state. Additionally, in August 1998, the ARB identified particulate 

emissions from diesel-fueled engines as toxic air contaminants. It is, by far, the largest 

contributor of known ambient air toxics cancer risk in California (ARB, 2009b). 

Following the identification process, the ARB developed the Risk Reduction Plan to 

Reduce Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles (Diesel 

Risk Reduction Plan) in September 2000, paving the way for the development of control 

measures designed to reduce toxic diesel PM emissions. Through this plan, staff 

identified strategies; including air toxics control measures and other regulations, to 

reduce diesel emissions by 75 percent by 2010, and by 85 percent by 2020. The goal 

of each regulation is to make diesel engines as clean as possible to reduce emissions 

and their associated cancer risk. The Truck and Bus and Drayage Truck regulations 

are critical pieces of the Diesel Risk Reduction Plan, as is evidenced by the significant 

emissions of diesel PM from the vehicles subject to those regulations. Failure to obtain 

substantial reductions in diesel PM from trucks and buses will likely mean the overall 

goals of the Diesel Risk Reduction Plan will not be met. 
-25-

III. PROPOSED AMENDMENTS TO THE TRUCK AND BUS REGULATION 

This chapter summarizes the proposed changes to the Truck and Bus regulation. Staff 

is proposing to amend the Truck and Bus regulation to implement the Board’s directive 

to provide additional flexibility for fleets adversely affected by the economy, while taking 

into account that emissions are lower than expected as a result of the recession. A 

detailed discussion of the proposed amendments to the Truck and Bus regulation can 

be found in Appendix D. 

A. Existing Regulation 

The existing Truck and Bus regulation applies to nearly one million diesel vehicles that 

annually operate in California with a manufacturer’s gross vehicle weight rating (GVWR) 

greater than 14,000 pounds, two-engine sweepers, yard trucks with on-road or off-road 

engines, and all diesel-fueled shuttle vehicles that frequent transit centers. The 

regulation does not include vehicles subject to previously adopted fleet regulations 

except for drayage trucks and utility-owned vehicles that become subject to the Truck 

and Bus regulation beginning January 1, 2021. 

Starting January 1, 2011, fleets are required to install PM filters for certain engine model 

years and to begin accelerating engine or vehicle replacement starting January 1, 2013 

so that by 2014, half of the vehicles in the fleet have 2010 model year or newer engines 

and the rest of the fleet have PM filters. PM filters include those that are originally 

installed by the manufacturer and those that are installed afterwards (PM retrofit). After 

2014, fleets are required to phase-in additional 2010 model year or newer engines such 

that by 2023 all engines operating in California and subject to the regulation will be 

model year 2010 or later or have been retrofitted to achieve equivalent emission 

reductions. 

Fleets may meet the annual requirements by retrofitting vehicles with a VDECS that will 

achieve PM or NOx reductions or both as required, replacing vehicles with newer 

cleaner ones that are originally equipped with PM filters by the manufacturer, or 

replacing existing engines with newer, cleaner engines. Fleets may also retire older 

vehicles, or operate higher emitting vehicles less often, designating them as low-use 

vehicles. 

The current regulation has three compliance options and fleets may change compliance 

options from one year to the next. The options include the following: 

• BACT Schedule - a schedule that specifies which vehicles must be equipped 

with a PM filter or replaced with 2010 model year engines to meet NOx and PM 

BACT based on engine model year 

• BACT Percentage Limit Option - a schedule that specifies the minimum number 

of PM filters to meet PM BACT and the minimum number 2010 model year 

engines required to meet both NOx and PM BACT in the fleet each year 
-26-

• Fleet Averaging Option - where annual PM and NOx emissions targets can be 

met by any combination of vehicles and retrofits that achieve similar emissions 

reductions as the first two options. 

The specific requirements of the current BACT Schedule and the current BACT 

Percentage Limit Option are shown below in Table III-1 and Table III-2, respectively. 

Table III-1: Current Best Available Control Technology Compliance Schedule 

Compliance 

Deadline, Jan 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 other 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 
-27-

Table III-2: Percent of Fleet That Must Comply with Current 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% 

Small fleets with three or fewer vehicles have an alternative compliance option that 

delays the first compliance date until January 1, 2014, as described below: 

• A one truck owner electing this option is required to have a 2004 model year or 

newer engine equipped with a PM filter by January 1, 2014. 

• A fleet with two trucks is required to have one 2010 model year engine and one 

truck equipped with a PM filter, or both trucks having a 2004 model year or 

newer engine and equipped with a PM filter by January 1, 2014. 

• A fleet with three trucks can elect to comply by having all vehicles equipped with 

2004 model year engines or newer with PM filters by January 1, 2014, or choose 

to delay the PM filter requirement for one truck until January 1, 2016 if another 

truck is equipped with a 2010 model year engine by 2014. 

All small fleets would need to meet the same BACT schedule as other fleets starting 

January 1, 2019. 

School buses are exempt from any NOx reduction requirements but must meet PM 

BACT requirements. School buses would have three compliance options to meet PM 

BACT starting January 1, 2011 so that all school buses would have PM filters by 

January 1, 2014. 

The regulation also includes a number of special provisions that delay some or all of the 

requirements for certain fleets and vehicle uses. These provisions are available for: 

• Low-use vehicles 

• Agricultural vehicles 

• Vehicles operating exclusively in designated NOx exempt areas 
-28-

• Motorcoaches 

• Unique vehicles 

The regulation also provides credits for: 

• Vehicle retirements that have occurred since 2008 

• Adding fuel efficient hybrid vehicles 

• Alternative fueled vehicles 

• Early PM retrofit installations 

B. Proposed Amendments to the Truck and Bus Regulation 

1. Overview 

The proposed amendments to the Truck and Bus regulation represent a significant 

overhaul and simplification to the existing regulation. Overall, the proposed 

amendments would exempt about 150,000 lighter trucks with a GVWR of 

26,000 pounds or less from meeting the PM filter requirements, and would delay any 

replacement requirements for their trucks until 2015. Heavier trucks (with a GVWR 

greater than 26,000 pounds) having 1998 to 2006 model year engines would be 

required to install PM filters between 2012 and 2014 which is a one year delay from the 

current initial PM filter requirements, and would be able to operate an additional eight 

years before being replaced. All other heavier trucks with 1997 model year and older 

engine would be required to be replaced from 2015 to 2017 when 20 years old or older. 

Overall, the initial requirements to modernize the fleet would be delayed by two years to 

2015, for both lighter and heavier trucks. From 2015 to 2020, fleets would be required 

to replace or upgrade engines that are 20 years old or older to 2010 model year engines 

or emissions equivalent. From 2020 to 2023, all remaining 2009 and older model year 

engines would be phased out, such that by 2023 all engines would meet 2010 model 

year emissions standards or have equivalent emissions. The fleet owner would have 

the option to delay replacement of any truck until 2020 by equipping the vehicle with a 

PM filter by January 1, 2014. 

2. Requirements for Lighter Vehicles (GVWR 26,000 pounds or less) 

Staff is proposing a new requirement for vehicles with a GVWR less than 26,001 

pounds. These lighter vehicles would no longer be subject to a PM filter requirement 

and would be instead required to be modernized. Starting January 1, 2015, and 

continuing each year thereafter until 2020, vehicles with engine model years that are 20 

years old or older would need to be replaced with vehicles equipped with 2010 model 

year engines or have equivalent emissions. Then, from 2020 to 2023, all remaining 

2009 model year and older engines would be required to be 2010 model year engines, 

or equivalent according to the following schedule. 

• 2003 and older engine model years by January 1, 2020 

• 2006 and older engine model years by January 1, 2021 

• 2009 and older engine model years by January 1, 2022 
-29-

By January 1, 2023, all vehicles in the fleet must have 2010 model year engines or have 

equivalent emissions. Fleets have an option to keep any lighter vehicle regardless of 

the engine’s model year until 2020 by equipping it with a PM filter prior to 

January 1, 2014. There are no other compliance options for these vehicles. 

3. Requirements for Heavier Vehicles (GVWR greater than 26,000 pounds) 

Staff is proposing that heavier vehicles with a GVWR greater than 26,000 pounds be 

required to comply with a BACT schedule that specifies the action required based on 

engine model year. The existing BACT schedule would be amended to require PM 

filters between 2012 through 2014 on newer engines and would delay vehicle 

replacements (without PM filters) until 2015 for older trucks. The proposed BACT 

compliance schedule is shown in Table III-3 below. According to the schedule, 1998 to 

2006 model year engines would be required to meet PM BACT between 

January 1, 2012, and January 1, 2014, and older vehicles would be required to 

modernize to 2010 model year engines or have equivalent emissions starting 2015. 

Under staff’s proposal, no engine less than 20 years old would be required to be 

replaced early until 2021. 

Table III-3: Proposed BACT Schedule for Heavy Weight Vehicles 

Compliance Deadlines 

Engine Model 

Install PM Filter By 2010 Engine By 

Pre 94 N/A January 1, 2015 

1994-1995 N/A January 1, 2016 

1996-1997 N/A January 1, 2017 

1998-2000 January 1, 2012 January 1, 2020 

2001-2004 January 1, 2013 January 1, 2021 

2005-2006 January 1, 2014 January 1, 2022 

2007-2009 

January 1, 2014 if not 

originally equipped 

with a PM filter 

January 1, 2023 

4. Optional Phase-In Schedule for Heavier Vehicles 

The proposed amendments also provide for an optional phase-in schedule for both 

large and small fleets that would allow them to spread out their compliance obligation in 

the early years. This would help ensure that no fleet will have to turn over an excessive 

amount of their vehicles in any single year. 

a) Large Fleets 

The proposed amendments provide for an optional phase-in compliance schedule to 

allow large fleets with trucks with a GVWR greater than 26,000 pounds to decide which 

of these vehicles to retrofit or replace, regardless of model year. This option would be 

especially beneficial for fleets with most or all of these vehicles in one or two model year 
-30-

ranges in the BACT compliance schedule as it allows fleets to spread out their 

compliance requirements. This option would allow fleets with engines originally 

equipped with PM filters to count them towards compliance, thereby reducing the overall 

number of retrofit PM filters needed. 

As shown in Table III-4, with this option, a fleet would phase-in PM filters (originally 

equipped or retrofit) at 30 percent per year from January 1, 2012 to 2014, and would 

require the remaining 10 percent of the fleet to be compliant with the BACT compliance 

schedule beginning January 1, 2016. With this option, any vehicle with a PM filter 

regardless of model year would be compliant until at least 2020. A fleet using this 

option would still need to meet the BACT schedule for all of their vehicles under 

26,001 pounds GVWR. 

Table III-4: Phase-In Option Schedule 

Compliance 

Date 

Vehicles with a GVWR 

More than 26,000 Pounds 

Equipped with a PM Filter 

January 1, 2012 30% 

January 1, 2013 60% 

January 1, 2014 90% 

January 1, 2015 90% 

January 1, 2016 All Must Comply with BACT 

Schedule 

b) Small Fleets with 3 or Fewer Trucks 

This proposed amendment would retain less stringent provisions for small fleets with 

vehicles with a GVWR greater than 26,000 pounds. Small fleets would still be defined 

as fleets of three or fewer total vehicles with a GVWR greater than 14,000 pounds 

subject to the regulation. The use of this option would not apply to trucks 

26,000 pounds GVWR or less that are not subject to the PM reduction requirements. 

As shown in Table III-5, small fleets would be required to demonstrate that one vehicle 

per year has a PM filter (originally equipped or retrofit) starting January 1, 2014. 

Table III-5: Small Fleet Phase-In Option Schedule 

Compliance 

Date 

Vehicles with a GVWR 

More than 26,000 Pounds 

Equipped with a PM Filter 

January 1, 2014 1 vehicle 

January 1, 2015 2 vehicles 

January 1, 2016 3 vehicles 
-31-

Beginning January 1, 2020, small fleet would need to comply with the BACT schedule 

like all other fleets. In addition, to utilize this option, small fleets would need to report 

beginning January 1, 2012. 

5. Credits 

A number of existing credits are proposed to be modified, and new credits would be 

added with the proposed amendments. 

a) Economic Relief for Fleet Size Reduction 

This amendment would provide expanded credits until 2016 for fleets that have fewer 

trucks than they had in 2006, and is intended to reduce the annual requirements for 

fleets most affected by the recession. Until January 1, 2016, and in conjunction with the 

optional Phase-in schedule for heavier trucks, a fleet would be able to reduce its 

requirement for a compliance year by the same percentage that the fleet has downsized 

from its 2006 baseline fleet. Table III-6 shows how the fleet size reduction credit would 

reduce the compliance requirements for a business that has 25 percent fewer vehicles 

than it did in 2006. Because the fleet is 25 percent smaller, the fleet would subtract 

25 percent from the annual phase-in option requirement each year until 2016. The 

second column in the table shows the phase-in option requirements without credits and 

the far right column shows the requirements adjusted for a fleet with a 25 percent 

smaller fleet. If the fleet size changes from year to year the credit would adjust. 

Table III-6: Example of Economic Relief for Fleet Downsized 25 Percent 

Compliance 

Date 

Vehicles Meeting 

PM BACT 

(No Credits) 

Fleet Size 

Compared to 

2006 Baseline 

PM BACT 

Required for 

Reduced Fleet 

January 1, 2012 30% -25% 5% 

January 1, 2013 60% -25% 35% 

January 1, 2014 90% -25% 65% 

January 1, 2015 90% -25% 65% 

January 1, 2016 All Must Comply with BACT Schedule 

The proposed changes would provide fleets with additional credits by extending the 

baseline year back from 2008 (the baseline year for determining credits in the current 

regulation) to 2006. This would provide more credit since nearly all fleets had more 

vehicles in 2006 than 2008. The proposed amendments would also increase the credit 

by allowing non-operational vehicles to be counted as retired (that is, excluded from the 

calculation of fleet size). The credit would also continue until January 1, 2016 rather 

than expiring January 1, 2014 as provided in the current regulation. To take advantage 

of these credits, fleets would be required to report information about all trucks with a 

GVWR greater than 26,000 pounds in the fleet and comply with the optional phase-in 

compliance schedule starting in January 2012. 
-32-

b) Early PM Retrofit Credits 

Fleets that have already installed a PM filter or install them prior to July 2011 would be 

able to treat another vehicle as compliant until 2017. This credit would encourage early 

action and would reward fleets for having installed PM filters. The vehicle that was 

retrofitted early would also be compliant until 2020. The proposed amendments would 

also extend the expiration date of the credit in the existing regulation from 2014 to 2017. 

However, these credits would not be available for action taken to comply with other 

regulations or for PM filters partially paid for by public funding according to the funding 

contract terms. 

This credit could be used by fleets in a number of ways, for fleets using the optional 

phase-in compliance schedule, the retrofitted vehicle and the credit would each count 

towards compliance. For example, a fleet with two early retrofits would be treated as 

having four PM filters until 2017. Alternatively, a fleet that complies with the BACT 

requirements and doesn’t report could claim the credit by reporting information about 

the truck equipped with the PM filter and the truck that would be treated as compliant 

using the provided credit. Additionally, a fleet that retrofits a lighter vehicle prior to July 

1, 2011, could treat a heavier vehicle as compliant until January 1, 2017. 

Overall, the amendment would increase the value of the existing early retrofit credit 

provision by providing a one for one credit that is good until January 1, 2017, rather than 

providing a credit like the existing regulation that declines each year until it expires 

January 1, 2014. 

In addition, any lighter or heavier vehicle that has a PM filter installed prior to 2014 

would be compliant until 2020. Fleets can use this option to keep older trucks until 2020 

even if the BACT compliance schedule would require the vehicle to be replaced 

between 2015 and 2020. Credit will not be given for partially state funded vehicle 

retrofits according to the funding program guidelines. 

c) Hybrid and Alternative Fuel Vehicle Credits 

Fleets that purchase fuel efficient hybrid vehicles, alternative fueled vehicles, or vehicles 

equipped with pilot ignition engines any time prior to 2017 would be able to treat another 

vehicle as compliant until 2017. This credit could be used with the optional phase-in 

compliance schedule where the credit for another vehicle would count towards 

compliance. In addition, a fleet that complies with the BACT requirements and doesn’t 

need to report the entire fleet could claim the credit by reporting information solely about 

the hybrid vehicle and the vehicle that would be treated as compliant using this credit. 

Like the early PM retrofit credit, this amendment would increase the value of the credits 

by providing a one for one credit rather than the credit value in the existing regulation 

that declines each year. Credit will not be given for partially state funded vehicle 

replacements according to the funding program guidelines. 
-33-

6. Other Changes 

a) Log trucks 

Fleets with log trucks (which are currently considered the same as other agricultural 

vehicles), would have an option to use an alternate phase-in schedule for 2010 and 

later model year engines on their log trucks starting 2014, and would be exempt from 

the PM filter requirements. As shown in Table III-7, the fleet would be required to 

phase-in 2010 model year engines, or equivalent, at a rate of 10 percent per year for 

the log trucks utilizing this option, beginning 2014, and to have all log trucks in the fleet 

equipped with 2010 model year engines or have equivalent emissions by 

January 1, 2023. Log trucks would need to be labeled like other agricultural vehicles, 

but would have no mileage restrictions and could operate statewide. 

Table III-7: Percentage of Log Trucks that Must have 2010 Model Year 

Emissions Equivalent 

Compliance Deadline 

As of January 1 

Percent of Total Fleet 

Complying 

2011 0% 

2012 0% 

2013 0% 

2014 10% 

2015 20% 

2016 30% 

2017 40% 

2018 50% 

2019 60% 

2020 70% 

2021 80% 

2022 90% 

2023 100% 

b) School buses 

Staff is proposing a number of amendments to the school bus provisions to provide 

economic relief to school bus fleets while still protecting children in the state. Staff’s 

proposal would exempt smaller school buses with a GVWR less than 26,001 pounds 

from the PM filter requirements and provide a one-year delay in the implementation of 

requirements for larger school buses – those with a GVWR greater than 26,000 pounds. 

The other proposed changes are similar to the relief proposed for other vehicles subject 

to the regulation. The BACT Percentage Limits option and the Fleet Averaging option 

would be eliminated and the existing BACT compliance schedule would be replaced 

with the phase-in compliance schedule shown in Table III-8 below. The fleet would be 

required to bring 33 percent of the diesel-fueled school buses with a GVWR greater 
-34-

than 26,000 pounds into compliance with PM BACT by January 1, 2012, 66 percent by 

January 1, 2013, and the rest of the fleet by January 1, 2014. 

Table III-8: Phase-In Compliance Schedule for School buses Greater than 

26,000 lbs GVWR 

Compliance Deadline, 

as of January 1 

Minimum Percent of Total 

Fleet Complying with BACT 

2012 33% 

2013 66% 

2014 100% 

The proposed amendments also include credits for installation of a PM filter on the 

smaller school buses, replacement purchases of smaller school buses, and for the 

purchase of hybrid, alternative-fueled, or heavy-duty pilot ignition school buses, 

provided that the funding of those buses allows the use of these credits. For each 

school bus that earns any of the credits described above, the fleet could treat another 

school bus as compliant because of the credit until January 1, 2014. The fleet would be 

required to keep records on the school buses receiving credit and the school buses to 

be treated as compliant. 

Similar to the proposal for other vehicle categories, staff is proposing a provision that 

offers economic relief to school bus fleets that have reduced their fleet size relative to 

their fleet size on October 1, 2006 – the new baseline year proposed in the amended 

regulation. Until January 1, 2014, a fleet would be able to reduce its requirement in a 

compliance year by the same percentage that the fleet has downsized from the 2006 

baseline fleet. The fleet may include all school buses with a GVWR greater than 14,000 

pounds when determining this credit. Except for fleets needing a compliance extension 

based on unavailability of PM filters, staff proposes to require no reporting for school 

bus fleets – only recordkeeping. 

c) Agricultural vehicles 

Staff is also proposing to extend the deadline for reporting agricultural vehicles until 

March 31, 2011 to allow another opportunity for eligible fleets to apply. Staff is also 

proposing to amend the definition of an agricultural vehicle to clarify the definitions and 

to allow non-qualifying trucks in agricultural fleets to utilize all other credits and 

provisions available to all other fleets. The definitions would clarify that any truck 

transporting a load of unprocessed crops between the farm and the first point of 

processing would be eligible. This would clarify that trucks would still be eligible if 

making interim movements between the farm an the processor and would include yard 

trucks. Staff is also proposing to change the definition of specialty agricultural vehicles 

to include all livestock feed trucks such as mixer-feed trucks rather than limiting the 

definition to use at cattle or calf feedlots. 
-35-

C. Effect of Proposed Amendments on Affected Fleets

To evaluate the effect of the proposed changes on affected fleets, staff developed a 

number of examples to demonstrate what actions would be required of fleets with the 

proposed amendments. All of the following examples are for the same fleet of heavier 

trucks with a GVWR of greater than 26,000 pounds and engine model years ranging 

from 1992 to 2006. This is shown in Table III-9 which lists the engine model years for 

the example fleet in the left column. 

Also shown in Table III-9 are the compliance requirements for meeting the current 

BACT schedule requirements of the existing regulation (shown in the middle column), 

and compliance requirements for the same fleet using proposed BACT schedule (shown 

in the right column). The subsequent examples use the same 10 vehicle fleet to show 

how a fleet could comply with the regulation by taking advantage of the proposed credit 

provisions. 

Table III-9: Existing and Proposed BACT Schedule Compliance Example 

Engine 

Model Year 

Existing 

Regulation 

Proposed 

Amendments 

1992 PM filter by 2011 and 

2010 engine by 2015 

2010 engine by 2015 

1994 2010 engine by 2013 2010 engine by 2016 

1998 2010 engine by 2013 PM filter by 2012 and 

2010 engine by 2020 

1999 2010 engine by 2013 PM filter by 2012 and 

2010 engine by 2020 

2000 2010 engine by 2013 PM filter by 2012 and 

2010 engine by 2020 

2001 2010 engine by 2013 PM filter by 2013 and 

2010 engine by 2021 

2003 PM filter by 2012 and 

2010 engine by 2016 

PM filter by 2013 and 

2010 engine by 2021 

2003 PM filter by 2012 and 

2010 engine by 2016 

PM filter by 2013 and 

2010 engine by 2021 

2006 PM filter by 2013 and 

2010 engine by 2017 

PM filter by 2014 and 

2010 engine by 2022 

2006 PM filter by 2013 and 

2010 engine by 2017 

PM filter by 2014 and 

2010 engine by 2022 

1. BACT Compliance Schedule 

The following example shows the example fleet using the BACT Compliance schedule 

that specifies the annual requirements by engine model year. The required compliance 

actions for this fleet are shown in Figure III-1. 
-36-

Figure III-1: Example of Compliance with BACT Schedule 

January 1 of Compliance Year Engine 

Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

1992 

1994 

1998 PM Filter 2010 Engine* 

1999 PM Filter 

2000 PM Filter 

2001 PM Filter 

2003 No Action PM Filter 

2003 PM Filter 

2006 PM Filter 

2006 PM Filter 

* The fleet could upgrade to 2007 – 2009 model year, and then upgrade in 2010 engine by 2023

The actions required are described below: 

• By January 1, 2012, the 1998 through 2000 model year vehicles would need to 

have a PM filter installed. By January 1, 2020, these vehicles would need to be 

upgraded to 2010 model year engine or equivalent emission. 

• By January 1, 2013, the 2001, model year engine and both of the 2003 modelyear engines would need to have PM filters installed. By January 1, 2021, the 

vehicles would need to be upgraded to 2010 model year engine or equivalent 

emission 

• By January 1, 2014, both of the 2006 model-year vehicles would need to have 

PM filters installed. By January 1, 2022, these vehicles would need to be 

upgraded to 2010 model year engines or equivalent emissions. 

• By January 1, 2015, the truck with the 1992 model-year engine would have to be 

replaced with one having a 2010 model year engine or equivalent emissions. 

• Finally, by January 1, 2016, the 1994 vehicle would need to be replaced with a 

2010 model year engine or equivalent emissions. 

2. Example Using the Phase-in Compliance Option 

Following is an example of the same example fleet utilizing the Phase-in Compliance 

Option. This option provides fleets with the flexibility to annually determine which trucks 

to either retrofit or replace with a truck having a PM filter originally installed from the 

engine manufacturer. Because this provision allows fleets to choose which vehicles 

they want to upgrade each year, there is no single option to meet these requirements. 

However, one potential compliance scenario is shown in Figure III-2. Note that in this 

example, it is assumed all PM filters are installed after July 1, 2011, and the fleet has no 

PM retrofit credits. 
-37-

Figure III-2: Example of Compliance with the Phase-in Option 

January 1 of Compliance Year Engine 

Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

1992 2007 Engine 

1994 30% PM Filter

1998 PM Filter 

1999 

2000 2008 Engine 

2001 30% PM Filter 

2003 PM Filter 2010 Engine*

2003 PM Filter 

2006 No Action 30% PM Filter 

2006 PM Filter 

* The fleet could upgrade to 2007 – 2009 model year, and then upgrade in 2010 engine by 2023

The actions used in this compliance example are described below: 

• By January 1, 2012, the fleet needs to show it has 30 percent of its vehicles 

(3 trucks) with PM filters, regardless of whether they are retrofits or originally 

equipped with the engine. In this example the fleet chose to upgrade the truck 

with a 1992 model year engine to a used truck with a 2007 model year engine 

and to install PM filters on the 1994 and the 1998 model year trucks. These two 

vehicles, which could be cranes or some other expensive vehicles, could then be 

kept in the fleet until 2020. 

• By January 1, 2013, the fleet would need to show that another 30 percent of the 

fleet has PM filters for a total of 60 percent. That means that three more 

vehicles would need PM filters. In this example the fleet chooses to replace its 

2000 model year truck with a 2008 model year truck already equipped with a PM 

filter and installs PM filters on the 2001 and 2003 model year trucks. 

• By January 1, 2014, the fleet installs PM filters on an additional 30 percent of the 

fleet, for a total of 90 percent of the trucks having PM filters. The 2003 model 

year and two 2006 model year engines would need to have PM filters installed. 

• By January 1, 2016, the fleet would replace the 1999 model year truck with a 

2010 or newer engine. 

• Starting January 1, 2020, the fleet would need to phase-in 2010 model year 

engines according to the BACT schedule for the remaining vehicles. 

3. Example of Credit for Fleets that have Downsized

Following is an example of the same example fleet as before except that is has reduced 

the number of trucks from 13 in 2006 to 10 trucks by the first compliance date; 

therefore, the fleet size was reduced by 23 percent. To take advantage of the fleet size 

reduction credits, fleets must report their fleet information and comply with the Phase-in 

Option. 

Table III-10 shows how the adjusted compliance requirement for this fleet would be 

determined. The second column shows the phase-in requirements, the middle column 

shows the fleet size reduction, and the right column shows the adjusted requirement 
-38-

after applying the credit. As shown in the table, the adjusted requirement is calculated 

by subtracting 23 percent from the annual compliance requirement in each year. 

Table III-10: Example of Adjusted Compliance Requirements for a Fleet 

That Downsized 23 Percent 

Compliance 

Date 

Vehicles Meeting 

PM BACT 

(No Credits) 

Fleet Size 

Compared to 

2006 Baseline 

PM BACT 

Required for 

Reduced Fleet 

January 1, 2012 30% -23% 7% 

January 1, 2013 60% -23% 37% 

January 1, 2014 90% -23% 67% 

January 1, 2015 90% -23% 67% 

January 1, 2016 All Must Comply with BACT Schedule 

Figure III-3: Example of a Fleet Utilizing Economic Relief Provision for Fleets that 

have Downsized

January 1 of Compliance Year Engine 

Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

1992 2007 Engine 

1994 2008 Engine 

1998 

1999 

2000 No Action 2010 Engine*

2001 

2003 PM Filter 

2003 PM Filter 

2006 PM Filter 

2006 PM Filter 

* The fleet could upgrade to 2007 – 2009 model year, and then upgrade in 2010 engine by 2023 

Figure III-3 shows the actions used in this compliance example which are described 

below: 

• By January 1, 2012, the fleet would need to show that 7 percent of the fleet or 

one truck (with rounding) meets PM filter requirement. Like the prior example, 

the fleet could comply by replacing its 1992 model year truck with a used truck 

having a 2007 model year engine that would be compliant until 2023. 

Additionally, the fleet would avoid installing two additional PM filters because of 

the credit. 

• By January 1, 2013, 37 percent of the trucks (four trucks total) would need to 

have PM filters to be compliant. Since one truck already has a PM filter three 

additional trucks would need to have PM filters. In this example the fleet 

upgrades the truck with the 1994 model year engine to a truck with a 2008 

model year engine that is compliant until 2023, and installs PM filters on both 

2006 vehicles that can be operated until 2022. 
-39-

• By January 1, 2014, 67 percent of the fleet (7 vehicles total) need to be 

compliant, meaning three more need to be brought into compliance. The fleet 

could install filters on both 2003 vehicles that would be compliant until 2021, and 

upgrade the truck with the 1998 model year engine to one with a 2010 model 

year engine that meets the final requirements. On January 1, 2016, the credits 

expire and the remaining three trucks need to meet the BACT compliance 

requirements. In this example the fleet upgrades to used vehicles with 2010 

model year engines. 

• Beginning January 1, 2021, the fleet would phase-in 2010 model year engines 

according to the BACT schedule for the remaining vehicles. 
-40-
-41-

IV. PROPOSED AMENDMENTS TO THE DRAYAGE TRUCK REGULATION 

This chapter discusses the proposed changes to the Drayage Truck regulation. The 

regulation is intended to reduce exposure to diesel PM in communities located near 

California’s ports and intermodal rail yards and to help meet the SIP goals for 2014. A 

detailed discussion of the proposed amendments to the Drayage Truck regulation can 

be found in Appendix E. 

A. Existing Drayage Truck Regulation 

The Drayage Truck regulation was approved by the Board in December 2007. The 

regulation applies to heavy-duty diesel drayage trucks having a GVWR greater than 

33,000 pounds and operating at California ports and intermodal rail yards. As adopted, 

it was to be implemented in two phases. Phase 1 of the regulation requires drayage 

trucks with pre-1994 model year engines to be phased out by 2010, 1994-2003 model 

year engines to be retrofitted with a level 3 PM filter starting in 2010 and 2004-2006 

model year engines be retrofitted with level 3 PM filter by 2012 and 2013. Phase 2 

requires drayage trucks to meet 2007 model year and newer engine standards by 2014. 

B. Proposed Amendments 

Staff is proposing several amendments designed to align the requirements of the 

regulation with the proposed amendments to the Truck and Bus regulation. The goals 

of the changes are to provide economic relief to drayage truck owners, to improve the 

cost effectiveness for retrofitting equipment, and to improve the enforceability of the 

regulation by preventing dray-off. The changes would also ensure that the PM 

exposure reduction goals for communities located near port and rail yards would 

continue to be met. 

Specifically, staff is proposing to extend the compliance period for retrofitted engines by 

eliminating the Phase 2 requirement of the regulation that requires drayage trucks to be 

equipped with engines that meet 2007 or later emission standards. The proposed 

changes would allow trucks to operate with PM filters at ports and intermodal rail 

facilities until 2020, which is an additional six years, at which time the Truck and Bus 

regulation would phase out older engines and require that all drayage trucks servicing 

the ports and intermodal rail yards be equipped with 2010 model year engines or have 

equivalent emissions. 

In addition, the Drayage Truck regulation would sunset on January 1, 2017. This 

corresponds to the date when the amended Truck and Bus regulation requirements 

would effectively require PM controls on all heavier trucks operating in California. 

Coincidental with this date, all reporting, labeling and record keeping requirements of 

the Drayage Truck regulation would no longer be required cease and all heavy-duty 

trucks in California would be subject to the Truck and Bus regulation. 

Staff is also proposing to mitigate dray-off activities by expanding the definition of a 

‘Drayage Truck’ to include trucks hauling cargos, containers, or chassis that are either 
-42-

bound from or destined for a port or rail yard. These proposed modifications would 

allow ARB enforcement to curtail dray-off activity occurring off of port and rail yard 

properties, which effectively circumvents the regulation. Noncompliant drayage trucks 

and their dispatching motor carriers would be subject to penalties for engaging in such 

activities. 

Staff is also proposing amendments to expand the definition of a drayage truck to 

include trucks with a GVWR of 26,001 – 33,000 pounds (class 7) trucks that operate at 

port and intermodal rail yards and require them to be operated with a level 3 PM filter by 

2014. This would ensure that the Board’s goal of quickly reducing PM exposure in 

communities located near ports and intermodal rail yards is continued. Because the 

existing Truck and Bus regulation already requires all (with few exceptions) trucks 

greater than 14,000 pounds to be equipped with a PM filter by January 1, 2014, this 

change would add no new requirements for these vehicles compared to current 

regulations. 
-43-

V. PROPOSED AMENDMENTS TO THE TRACTOR-TRAILER GHG REGULATION 

This chapter discusses the proposed changes to the Tractor-Trailer GHG regulation. 

Staff is proposing to amend the regulation to provide fleets with additional flexibility in 

meeting its requirements, to simplify compliance planning, and in many cases to reduce 

compliance costs, with minimal impact on the GHG benefits of the regulation. A 

detailed discussion of the proposed amendments to the Truck and Bus regulation can 

be found in Appendix F. 

A. Existing Regulation 

The Tractor-Trailer GHG regulation was approved by the Board on December 12, 2008. 

The current regulation requires 2011 model year and newer tractors that pull 53 foot 

and longer box type trailers to be U.S. EPA SmartWay certified. The current regulation 

requires pre-2011 model year tractors to use all SmartWay verified tires by 

January 1, 2012. In addition, the regulation requires that 53 foot and longer box type 

trailers affected by this regulation must either be U.S. EPA SmartWay certified or be 

retrofitted with SmartWay approved technologies (aerodynamic devices and low rolling 

resistance tires). 

The current regulation offers owners of large trailer fleets two different options for 

bringing their pre-2011 model year trailers into compliance. They may either bring their 

entire trailer fleet into compliance by January 1, 2013, or register for and participate in 

an optional compliance phase-in schedule that would give the fleet six years to comply, 

between 2010 and 2015. To participate in the optional phase-in, fleets must have 

already registered with ARB by July 1, 2010. The total number of large fleet owners 

that registered by the deadline was 95, registering approximately 180,000 trailers. 

B. Proposed Amendments to the Tractor-Trailer GHG Regulation 

The specific amendments staff is proposing are as follows: 

• Add a second optional large fleet compliance schedule which would begin a year 

after the existing large fleet compliance schedule, but end at the same time. This 

option would provide an additional year for fleets that were not aware of this 

regulation to register and participate in an optional compliance schedule. 

• Provide the option to report compliance on an annual basis for trailers participating 

in an optional compliance schedule, rather than on an up-front, one-time basis as 

currently required. 

• Add language allowing owners of trailers to modify SmartWay verified aerodynamic 

equipment from its original verified configuration, subject to Executive Officer 

approval. 

• Add an exemption from the aerodynamic and tire requirements for storage trailers. 

• Add a limited term exemption from the aerodynamic technology requirements for 

trailers that are configured such that none of the SmartWay verified aerodynamic 
-44-

technologies can be effectively installed on them; the exemption would require 

Executive Officer approval. 

• Exempt empty local-haul trailers from meeting the aerodynamic equipment 

requirements and empty storage trailers from meeting both the aerodynamic 

equipment and tire requirements when they are being relocated to another local-haul 

base or storage location. 

• Provide for temporary passes to allow local-haul and storage trailers loaded with 

freight to travel on California highways on a temporary basis without the required 

aerodynamic technologies and low rolling resistance tires. These include a 

relocation pass and a transfer of ownership pass. 

• Provide for a temporary pass for tractors, and the trailers they pull, that only travel in 

California once a year, allowing them to travel on California highways without the 

required aerodynamic technologies and low rolling resistance tires for a period of no 

more than three days, subject to Executive Officer approval. 

• Require California-based vehicle dealers of 53-foot and longer box-type trailers and 

heavy duty tractors to maintain records of the disclosure statement given to buyers 

regarding the Tractor-Trailer GHG regulation. 

• Extend the deadlines by one year for tractors and four years for trailers for requiring 

use of low rolling resistance tires on all pre-2011 model year tractors and trailers; the 

deadline for tractors would be January 1, 2013, and for trailers January 1, 2017. 

• Provide a limited term exemption to allow the use of open shoulder drive tires on 

2011 and subsequent model year tractors. Open shoulder tires are tires where the 

outermost tread is separated into blocks that are designed to provide traction when 

traveling on mud or snow covered highways. This exemption would sunset on 

January 1, 2013. 

Staff is also proposing several administrative changes to the regulation to improve 

clarity and enforceability of the regulation. 

C. Effect of Proposed Amendments on Individual Fleets 

The proposed amendments to the Tractor-Trailer GHG regulation would provide 

additional flexibility to affected fleets in meeting the requirements of the regulation, 

improve the ability of fleets to periodically adjust their compliance plan and in some 

cases reduce compliance costs, with a minimal impact on the GHG benefits initially 

approved. 
-45-

VI. ENVIRONMENTAL IMPACTS 

This chapter describes how the proposed amendments continue to achieve needed 

emissions reductions, reduce localized risk from exposure to diesel PM, reduce impacts 

of diesel engine emissions on mortality and other health effects and meet SIP 

commitments to meet federal air quality standards. 

A. Legal Requirements 

The California Environmental Quality Act (CEQA) and ARB policy require an analysis to 

determine the potential environmental impacts of proposed regulations. The legal 

requirements applicable to the environmental impact analysis are the same as those 

presented in Chapter XII, Section A of the Technical Support Document for the original 

regulation (ARB, 2008a). 

The results of the analysis of the environmental impacts of the proposed amendments 

are presented below. Alternatives to the proposed amendments are discussed in 

Chapter VIII 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, while addressing the serious economic recession and its impact on industry 

and residents of the State. 

B. Emission Impacts from Proposed Amendments 

1. Emissions Benefits of the Proposed Amendments 

Staff anticipates the proposed amendments to the Truck and Bus regulation and the 

Drayage Truck regulation would reduce diesel PM emissions by 50 percent from 

baseline levels in 2014 and ensure that by 2020 practically all trucks operating in 

California will be equipped with a diesel PM filter. The revised baseline truck emissions 

inventory and the impact of the regulation on emissions in years relevant to attainment 

of federal clean air quality standards are shown below in Table VI-1 

Table VI-1: Impact on Statewide NOx and PM Emissions 

NOx Emissions PM Emissions 

Year Without 

Regulation 

Proposed 

Regulation Benefits Without Regulation 

Proposed 

Regulation Benefits

2014 422 421 0 15.5 8.6 6.9 

2017 339 305 34 11.8 5.6 6.2 

2020 276 231 44 9.4 5.3 4.0 

2023 245 157 88 7.8 5.2 2.6 

Figure VI-1 compares anticipated emissions without the regulation to emissions with the 

amended regulation, as currently proposed. Both lines in the graph include the effect of 

the recession. 
-46-

Figure VI-1: Statewide Truck and Bus PM Emissions* 

0

5

10

15

20

25

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

PM2.5 (tons per day)

* Vehicles subject to either the Truck and Bus or Drayage Truck regulation

Staff also anticipates the amended regulations would achieve a 36 percent reduction in 

statewide NOx emissions in 2023, and an overall 15 percent reduction in statewide NOx 

emissions from baseline levels between 2015 and 2023. Figure VI-2 compares 

anticipated emissions without the regulations to emissions with the proposed 

amendments. 

Without Regulation 

With Regulation 
-47-

Figure VI-2: Statewide Truck and Bus NOx Emissions*

0

100

200

300

400

500

600

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

NOx (tons per day)

* Vehicles subject to the Truck and Bus regulation and Drayage Truck regulation 

2. Comparison of Emissions Benefits to Existing Regulation 

The proposed amendments would still achieve most of the PM emissions reductions 

compared to the exiting regulation, but would not achieve as much NOx emissions 

reductions. Table VI-2 compares the benefits of the current regulation and the 

regulation as proposed to be amended. The PM benefits of the proposed amendments 

are lower in 2014 but are nearly the same starting 2017 because all heavier trucks will 

have PM filters like the existing regulation requires. Lighter trucks would be exempt from 

PM filter requirements, but by 2021 all lighter trucks would have trucks with originally 

equipped PM filters. Lighter trucks have lower emissions per mile traveled and 

contribute much lower emissions than heavier trucks. The NOx benefits of the 

proposed amendments are lower than if the current regulation were implemented, 

through 2020. However, by 2023, all engines must still be 2010 model year engines or 

have equivalent emissions. 

Without Regulation 

With Regulation 
-48-

Table VI-2: Benefits of the Current Regulation Compared to the 

Proposed Amendments (tpd) 

NOx Benefits PM Benefits 

Year Existing 

Regulation

Proposed 

Amendments

Existing 

Regulation 

Proposed 

Amendments

2014 106 0 11.2 6.9 

2017 102 34 7.1 6.2 

2020 71 44 4.4 4.0 

2023 84 88 2.7 2.6 

3. PM and NOx Emissions Benefits are Preserved 

a) Combined On-Road and Off-Road Emissions 

The proposed regulatory amendments across both the Truck and Bus and Off-Road 

regulations are designed to provide the maximum amount of economic relief while still 

preserving as much of the originally envisioned benefits as possible. Our estimates 

suggest that the combined statewide impact of the recession with the proposed 

amendments to the Truck and Bus and Off-Road regulations will provide essentially the 

same cumulative remaining emissions levels between 2011 and 2023 as was expected 

with the existing regulations before the recession. These estimates are shown in Figure 

VI-3 and Figure VI-4 for PM2.5 and NOx respectively 

As can be seen in Figure VI-3, while the emissions that would occur in the early years 

with the proposed amendments are not equivalent to those that would be achieved with 

the current regulation, cumulatively the amended regulation would result in essentially 

the same NOx and PM2.5 emissions levels compared to what was expected when the 

regulation was approved by the Board before the recession. More information on the 

preservation of benefits expected with emissions is detailed in Appendix G. 
-49-

Figure VI-3: Year by Year Comparison of Truck and Bus and Off-Road 

PM Emissions after Regulation is Applied: Current Rule Without 

Recession vs. Amended Rule with Recession 

0

5

10

15

20

25

30

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Statewide PM2.5 Emissions (tons/day)

Adopted Without 

Recession 

With Proposed 

Amendments 
-50-

Figure VI-4: Year by Year Comparison of Truck and Bus and Off-Road NOx 

Emissions after Regulation is Applied: Current Rule Without 

Recession vs. Amended Rule with Recession 

0

100

200

300

400

500

600

700

800

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Statewide NOx Emissions (tons/day)

b) Emissions Impacts from Drayage Trucks 

Because the requirement for drayage trucks have 2007 model year and newer engines 

by 2014 has largely been achieved through the Clean Truck Programs at the Ports of 

Los Angeles and Long Beach, minimal air quality impacts from the elimination of the 

Phase 2 requirements of the Drayage Truck regulation in the South Coast Air Basin are 

anticipated. Under this program, both Ports required all trucks to emit at or below 2007 

model year and newer emission standards by January 1, 2012, a full two years ahead of 

the current Drayage Truck regulation’s requirement. As such, most drayage fleets 

operating at the Southern California ports have already modernized to meet the existing 

Phase 2 requirements. 

In addition, the downturn in the economy has resulted in lower cargo volumes and 

drayage truck activity than previously expected, further reducing NOx and PM 

emissions below the levels expected during the implementation of Phase 2. 

Adopted Without Recession 

With Proposed Amendments 
-51-

The proposed amendments to the Drayage Truck regulation would reduce expected 

2014 NOx emissions benefits by 7.4 tons/day (primarily outside the South Coast Air 

Basin), which is a 13 percent increase in remaining emissions statewide. This reduction 

in benefits will be experienced mostly in the San Francisco Bay Area. However, this 

region already meets the PM2.5 standard. The emissions impact will not have a 

significant effect in the San Joaquin Valley because drayage trucks travel less than 1 

percent of their miles in the San Joaquin Valley. Because all drayage trucks will be 

equipped with a PM filter by 2014, reductions in directly emitted diesel PM emissions 

from drayage trucks in all regions of the State will be unaffected. 

C. Impact on SIP Targets 

Per the direction of the Board, staff considered the maximum economic relief that could 

be provided while ensuring that all applicable SIP targets were met. To do this, staff 

considered the impact of the recession and inventory changes on both truck and buses 

and off-road vehicles together in deciding how to provide appropriate economic relief. 

This approach allowed staff to better target emissions reductions across the two 

categories of vehicles while continuing to ensure that the combined emissions targets in 

the SIP were met. 

As previously discussed, to determine how much economic relief could be provided and 

still meet applicable SIP remaining emissions targets, staff compared what emissions 

were expected to be remaining with the existing regulations and the pre-recession 

inventories to what emissions are expected to be with the proposed amendments and 

the updated inventories. The difference between these two is the emission margin. 

Since there are SIP targets for both NOx and PM2.5, staff expressed the margin as a 

weighted total of the two in NOx equivalent terms. The margin is 62 TPD of NOx 

equivalent emissions in the South Coast in 2014, and 40 TPD in the San Joaquin 

Valley. 

Next, to evaluate whether the proposed amendments still met all applicable SIP targets, 

staff compared the remaining emissions from these vehicles, after applying the benefits 

of the proposed amendments and the revised emission inventories, to the 2014 SIP 

margins in the South Coast and San Joaquin Valley. In the San Joaquin Valley the 

proposed amendments reduce the margin to zero, meaning that the emission levels 

(after considering the amendments and the recession) will be at the same level that was 

expected with the existing regulation before the recession. In the South Coast, the 

margin will be reduced to about five tons per day NOx equivalent. Overall, this 

demonstrates that the proposed amendments continue to provide maximum economic 

relief while meeting all applicable SIP targets for trucks and buses and off-road vehicles. 

D. Impact on PM Mortality 

Even with the major amendments and economic relief proposed, the regulations would 

provide significant health benefits by reducing premature mortality from PM2.5 exposure 

and localized risk from diesel PM. Staff estimates that 3,500 premature deaths (2,700 

to 4,400, 95 percent confidence interval) would be avoided by implementation of the 
-52-

amended truck regulations from 2010 to 2025. This estimate is based on U.S. EPA’s 

new risk assessment methodology (U.S. EPA, 2010), and includes the most recent air 

quality data available (2006 to 2008) and the latest emissions inventory estimates. 

E. Impact on Localized Risk 

The proposed amendments continue to reduce PM emissions from trucks and buses by 

the maximum feasible amount, and even with the proposed amendments, the 

regulations will significantly lower diesel PM emissions. Staff estimates that by 2014, 

diesel PM emissions would be reduced by 48 percent, and by 2020, nearly every truck 

operating in California will have a PM filter. The Diesel Risk Reduction Plan set a goal 

to reduce diesel PM by 85 percent when compared to 2000. The proposed 

amendments meet the goals of the plan by achieving the maximum feasible PM 

reductions. 

F. Impact on Climate Change Emission 

Recent studies by scientists cited in the IPCC’s report estimate that emissions of black 

carbon (BC) are the second largest contributor to global warming, after carbon dioxide 

emissions (Ramanathan and Carmichael, 2008). Studies in the peer-reviewed literature 

also indicate that BC emissions cause warming primarily in the region where they are 

emitted. Therefore, it is important to understand that BC’s warming impact requires 

close attention to the geography of emissions. A study published this year shows that 

the darkening of snow and ice by black carbon deposition is a major factor for the rapid 

disappearance of snow packs. The observed trend toward earlier melting of the snow 

packs in the Sierras is an important factor in water supply problems in California 

(Hadley et al., 2010). 

Reviewing all source categories of PM2.5 emissions, the BC content is greatest for 

diesel exhaust. Fifty percent of PM2.5 emissions from on-road diesel exhaust consists 

of BC, while 40 percent of PM2.5 emissions from off-road diesel exhaust consists of BC 

(Chow et al., 2010). By estimating the BC fraction of diesel PM and the GWP of BC, 

using 500 GWP100-yr and 2000 GWP20-yr (Hansen et al., 2007), the approximate 

climate warming effect of the proposal to amend the Truck and Bus regulation for 2025 

is 6 and 22 million metric tons of carbon dioxide equivalents (MMTCO2-eq) for 100-year 

and 20-year time horizons, respectively. 

Estimates of the reduced climate warming impacts from BC emissions for proposed 

statewide off-road diesel truck regulation for 2010-2029 are about 1 and 4 MMT CO2-eq 

for 100-year and 20-year time horizons, respectively. These estimates represent 

considerable reductions in global warming impacts from current BC emissions based on 

baseline regulations. Finally, although use of a GWP may be a helpful tool to assess 

the importance of BC climate warming impact, the GWPs of atmospheric short-lived 

compounds (e.g. non Kyoto compounds such as BC) are more uncertain and their 

climate forcing will strongly depend on the location and timing of the emission. 
-53-

The proposed amendments to the Tractor-Trailer GHG regulation will not impact the 

2020 GHG emission benefits from the original regulation which is approximately 0.7 

million metric tons of CO2-equivalent (MMT CO2e) in California. However, because the 

proposed provisions delay tractor-trailer compliance deadlines with the low rolling 

resistance tires, the 2010 to 2020 cumulative statewide GHG emission benefits will be 

reduced by approximately 6 percent, from 5.1 MMTCO2e to 4.8 MMT CO2e. This 

emission benefit loss is minimal compared to the overall emission benefits of the 

program and the necessary flexibility it provides fleets to ease the burden of 

compliance. 

G. 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 concerns be addressed in all of ARB’s 

regulatory programs 

The proposed amendments to the Truck and Bus, Tractor-Trailer GHG, and Drayage 

Truck regulations are consistent with the goals of the current regulations to reduce PM, 

NOx, and greenhouse gas emissions, as well as reduce the associated cancer risks and 

other health impacts over time statewide. This is consistent with the ARB’s 

environmental justice 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. 

H. Other Environmental Impacts 

The emissions benefits from the amended regulation would be lower than the existing 

regulation; however, the proposed amendments would reduce the cost of the regulation 

by more than 50 percent. More significantly, with the proposed regulation, the capital 

investments required in the next five years would be dramatically reduced because all 

vehicle replacement requirements have been delayed by 2 years and now would only 

be required for trucks that are 20 years old or older. With the recession, the ability of 

fleets to borrow and make needed capital investments has been significantly reduced. 

Although, the proposed amendments do not achieve the same emissions reductions, 

the reduced economic impacts on fleets outweighs the disadvantages. More detailed 

information on health impacts and benefits and methodology is provided in Appendix J. 

I. Conclusion 

The proposed amendments would result in foregone emission reductions compared to 

the current regulation. However, ARB staff believes there are overriding economic and 

social considerations driving these proposed changes. The recession has significantly 

impacted the economic health of the regulated industry and, consequently, has greatly 

affected its ability to comply with the current regulation. Additionally, the recession has 

had significant social implications, causing a number of businesses to reduce their 

activities or go out of business, which has resulted in significant unemployment 

throughout the State. The recession has also caused emissions to be lower than 
-54-

anticipated when the regulations were initially approved. Hence, in addressing 

concerns with respect to CEQA, staff is proposing that the Board find that overriding 

considerations exist. 
-55-

VII. ECONOMIC IMPACTS 

This chapter discusses the effect of the proposed amendments on individual fleets and 

businesses affected by the regulations in more detail. 

The proposed amendments to the Truck and Bus regulation and Drayage Truck 

regulation are expected to provide substantial economic relief to all affected fleets. The 

proposed amendments to the Tractor-Trailer GHG regulation would primarily provide 

compliance flexibility, but would not result in significant changes in costs. 

A. Truck and Bus Regulation Amendments 

1. Cost Methodology 

To estimate the economic impacts of the proposed amendments, staff utilized an overall 

methodology that was similar to the one used when originally estimating the costs for 

the initial 2008 rulemaking. The estimated costs were calculated by predicting and 

evaluating the compliance paths for real individual fleets; these estimates were then 

scaled to statewide costs using the estimated population in the statewide fleet. (ARB, 

2008c) 

To evaluate the costs (and cost savings) of the proposed amendments, the compliance 

plan modeling was done using updated access database code previously used for the 

original rule making. For this effort, 200 real fleets were utilized. The most significant 

change to the modeling methodology was to add a method to reflect slower truck 

replacement rates for several years to reflect the impacts of the recession consistent 

with the rates reflected in the emissions inventory. 

For each fleet in the truck compliance model, staff calculated the costs the fleet would 

normally spend without the regulation over the period of 2011 to 2025. These costs are 

referred to as a fleet’s baseline costs, and depend upon a fleet’s average age, the 

replacement vehicle age and the calculated normal turnover rate. Once the baseline 

cost for a fleet was determined, a compliance cost was then calculated, based on a 

fleet’s anticipated compliance path over the same time period. The difference between 

a fleet’s baseline cost, and a fleet’s compliance cost is the cost attributed to the 

regulation. Annual costs for reporting, PM filter maintenance, and the estimated effect of 

credits were calculated and added into the overall cost estimate separately. More 

information on the vehicle and retrofit costs used to calculate a fleet’s baseline cost and 

compliance costs are in Appendix I. 

2. Estimated Costs for Amended Truck and Bus Regulation 

As compared to the current regulation, the proposed amendments would reduce 

compliance costs for all affected fleets by: 

• Reducing the number of required retrofits 

• Providing a longer period of time for retrofitted trucks to operate before having to 

upgrade to a 2010 MY engine or equivalent. 
-56-

• Delaying truck replacements substantially 

• Extending credits for early retirement and alternative-fueled and hybrid trucks. 

Table VII-1 provides a comparison of what actions would be required with the existing 

regulation for all in-state registered trucks with a GVWR greater than 14,000 pounds in 

comparison to the proposed amendments without any compliance credits. 

Table VII-1: Comparison of 2014 Actions Required (Percentage of Trucks) 

Action Proposed 

Amendments 

Existing 

Regulation 

Early Replacements 0% 28% 

PM Retrofit Filters 28% 30% 

Business as Usual 72% 42% 

Total 100% 100% 

As is shown in Table VII-1, prior to 2015, the existing regulation would require 

28 percent of the vehicles to be replaced early, compared to the proposed amendments 

that would not require any vehicle to be replaced early. Both the existing regulation and 

proposed amendments would require retrofit PM filters on about 30 percent of all trucks 

with a GVWR greater than 14,000 pounds. However, the proposed amendments would 

exempt lighter trucks (less that 26,001 pounds GVWR), representing about 30 percent 

of the total population, from meeting the PM filter requirements. Cumulatively, nearly 

75 percent of the trucks would be replaced as normal and would remain compliant with 

the proposed amendments, as compared to just over 40 percent with the current 

regulation. 

Overall, the estimated costs of the Truck and Bus regulation would be reduced 

substantially. The net investments required in the first five years would be reduced from 

$3.3 billion to about $1.5 billion, a reduction of more than 50 percent. For the life of the 

regulation the overall cost would be reduced by about 60 percent - from $5.5 billion to 

about $2.2 billion. Average costs for businesses such as local contractors, retailers and 

local moving companies, would be reduced by 70 percent, with nearly all of the costs 

being eliminated entirely for thousands of small businesses with lighter trucks. Figure 

VII-1 shows how the average statewide costs of the regulation would decline compared 

to the original estimates for the current regulation. 

While businesses in the transportation sector would experience substantial cost 

savings, the amount of savings could vary significantly. For example, a long haul 

truckload carrier that replaces its fleet within a 7-year cycle would continue to have no 

costs attributable to the regulation. A less than truckload carrier that replaces the fleet 

within an 8 year cycle would have no costs other than one year of reporting with the 

proposed amendments instead of having to install PM filters on 10 percent of the fleet 

with the existing regulation. This would be a greater than 90 percent cost savings. 

Fleets that replace their trucks within a 10-year cycle would need to install PM filters on 

10 percent of their trucks with the proposed amendments instead of 20 percent of their 
-57-

trucks as is currently required in the existing regulation which would be a 50 percent 

cost savings. 

Figure VII-1: Cost of Proposed Truck and Bus Regulation Down Substantially 

$0.0

$1.0

$2.0

$3.0

$4.0

$5.0

$6.0

Cost (Billions)

First 5 Years Total Regulation

Proposed

Existing

Additionally, as can be seen in Table VII-2, the overall cost effectiveness of the 

proposed regulation with the updated inventory would be improved slightly to $1.70 per 

pound of NOx reduced and $44 per pound of PM reduced. This compares to the cost 

effectiveness of the existing regulation originally estimated at $1.76 per pound of NOx 

reduced and $46 per pound of PM reduced. 

Table VII-2: Cost Effectiveness Ratio Comparison 

Emission 

Reductions

Proposed 

Amendments

Current 

Regulation 

NOx ($/lb) $1.70 $1.76 

PM ($/lb) $44.20 $46.00 

Although the proposed amendments achieve fewer emissions benefits than the current 

regulation, overall cost effectiveness for both NOx and PM has improved. This is 

largely due to the fact that 150,000 lighter vehicles would no longer need to be retrofit 

and tend to have relatively low miles and represent a small proportion of the emissions. 

Also, for heavier vehicles, fleets may now retrofit a vehicle without needing to replace it 

early, and older vehicles would not need to have PM retrofits and could be replaced with 

a new or used replacement one time. With the proposed changes, fewer vehicles would 

need to be retrofit and then replaced early. Only 3 percent of trucks are older than 20 
-58-

years old. The methodology used to calculate cost effectiveness is the same as 

described in the TSD for the original truck and bus regulation rulemaking (ARB, 2008a). 

The proposed amendments would not impose any additional costs on small businesses, 

and in fact should result in small businesses, many of them small fleets, being able to 

spread out the compliances costs over a longer period of time, thus, lowering their 

average yearly compliance costs. 

The proposed amendments would also provide expanded credits for early retrofits and 

reduce the requirements for fleet that have downsized. The proposed changes would 

also provide fleets with additional credits and economic relief by changing the baseline 

year for vehicle retirement credits from 2008 to 2006, by allowing non-operational 

vehicles to count as retired, and extending the credit period for vehicle retirement from 

2014 to 2017. 

3. Costs Analysis for Individual Fleets 

Although the overall economy for trucks is down about twenty percent on average, 

some fleets and sectors are more affected than others. Staff collected survey data from 

fleets and analyzed the savings expected from the proposed amendments for some 

individual fleets. 

a) Moving Company 

The following company is an actual moving fleet with 14 trucks, seven of which are 

heavier trucks (more than 26,000 pounds GVWR) and the others are lighter trucks (less 

than 26,001 pounds GVWR). The engine model years for the trucks range from 1996 to 

2007. The fleet has downsized 30 percent since 2006 and typically will replace one 

truck per year at a cost of about $94,000 after trade-in. Staff assumed the annual 

revenue of this company for 2010 would remain the same as in 2009. From 2006 to 

2010 the average annual revenue was about $4.9 million. 

The existing regulation would require the fleet to install six retrofit PM filters and to 

replace eight trucks one to two years earlier than normal. The fleet’s total costs with the 

existing regulation above normal replacement costs from 2010 to 2025 would be 

$160,000 (2010 dollars). 

With the proposed amendments the fleet would need to install two retrofit PM filters and 

replace two trucks one year early. Figure VII-2 shows the annual expenditures the 

company would make in current dollars with the proposed amendments compared to 

the existing regulation. The average normal replacement costs are shown by the 

dashed line. With the proposed amendments, the fleet’s total compliance costs would 

be reduced to about $74,000 above normal replacement costs, or 55 percent lower than 

with the current regulation. More importantly the proposed amendment would impose 

no additional costs other than business as usual for this fleet until 2014, in part, 

because of the credits for downsizing. By January 1, 2014, the fleet would need to 
-59-

install one PM filter on an existing truck. The cost to comply would represent about 

0.15 percent of annual revenue. 

Figure VII-2: Moving Company Annual Rule Costs vs. Normal Replacement Costs 

$0

$50,000

$100,000

$150,000

$200,000

$250,000

2010201120122013201420152016201720182019202020212022202320242025

Proposed

Existing

Average Normal

Replacment Costs

b) Concrete Company 

Staff also evaluated the impact of the proposed amendments for an actual concrete 

company. The concrete company has 18 trucks with engine model years ranging from 

1994 to 2007, all of which are heavier trucks with a GVWR greater than 26,000 pounds. 

The company has annual revenues above $3,000,000. The fleet has the same number 

of trucks as it did in 2006, but it has not been operating six of the trucks. Therefore, the 

fleet could utilize a 33 percent economic relief credit (six out of 18 trucks). The fleet 

typically replaces one truck per year at a cost of about $103,000 per year after trade-in. 

Staff assumed the annual revenue of this company for 2010 would remain the same as 

in 2009. From 2006 to 2010 the average annual revenue was about $6.5 million. 

The existing regulation would require the fleet to install eight retrofit PM filters and to 

replace 14 trucks one to six years earlier than normal. With the existing regulation, the 

fleet’s cumulative compliance costs from 2010 to 2025 are expected to be $440,000 

(2010 dollars) above normal replacement costs. 

With the proposed amendments, the fleet would be expected to install seven retrofit PM 

filters and to replace nine trucks early. Figure VII-3 shows the annual expenditures the 

company would make in current dollars with the proposed amendments compared to 

the existing regulation. One truck is replaced one year early in 2016 because the fleet 

would not be expected to install a PM filter on a truck that would normally be replaced in 

one year. Most of the early replacements occur from 2021 to 2023. With the proposed 

amendments, the fleet’s cumulative compliance costs from 2010 to 2025 would be 

reduced to about $230,000 above normal replacement costs or about 50 percent lower 
-60-

than with the current regulation. More importantly the amended regulation would 

impose no costs for this fleet until 2014 when three PM filters would be required 

compared to substantially higher costs with the existing regulation. In 2016, one more 

truck than normal was replaced 2 years early and reflects that a fleet would not be likely 

to install a retrofit PM filter on a truck that was about to be replaced. 

Figure VII-3: Concrete Company Rule vs Normal Replacement Costs 

$0

$50,000

$100,000

$150,000

$200,000

$250,000

$300,000

$350,000

$400,000

$450,000

2010201120122013201420152016201720182019202020212022202320242025

Proposed

Existing

Average Normal

Replacment Costs

c) Transportation Company 

The following company is an actual freight transportation fleet, primarily a truckload 

carrier, with 33 truck tractors (GVWR greater than 26,000 pounds). The engine model 

years range from 1990 to 2009. Staff assumed the annual revenue of this company for 

2010 would remain the same as in 2009. From 2006 to 2010 the average annual 

revenue was about $5.5 million. The fleet did not provide information about the number 

of trucks in 2006; therefore, staff did not assume the fleet size declined and no 

economic relief credits for downsizing would apply in this example. The fleet typically 

replaces two trucks per year with used trucks that are three years old at a cost of less 

than $45,000 per truck after trade-in. 

The existing regulation would require the fleet to install 14 retrofit PM filters and to 

replace 27 trucks one to six years earlier than normal. The cost increase in 2010 

reflects that the fleet would purchase a newer truck than normal that is originally 

equipped with a PM filter. The fleet would be expected to replace some trucks early in 

planning to meet future NOx reduction requirements while reducing the number of 

retrofit PM filters. The fleet’s total costs to comply with the existing regulation from 2010 

to 2025 would be $410,000 (2010 dollars) above normal replacement costs with the 

highest capital investments required 2012 to 2014. 
-61-

With the proposed amendments the fleet would be expected install 16 retrofit PM filters 

and to change the order in which the older trucks are replaced. Figure VII-4 shows the 

annual expenditures the company would make in current dollars with the proposed 

amendments compared to the existing regulation. The fleet would continue to replace 

two trucks per year until 2016 when the fleet would need to replace four trucks. In 2022 

and 2023 the fleet would need to replace 11 trucks early. With the proposed 

amendments, the fleet’s total compliance costs would be reduced to about $185,000 

above normal replacement costs, or 55 percent lower than with the current regulation. 

The capital investments required from 2010 to 2015 would be about 50 percent lower. 

The cost increase in 2010 reflects that the fleet has begun to purchase newer trucks 

than normal that are originally equipped with a PM filter. The average normal 

replacement costs are shown by the dashed line. The cost to comply with the proposed 

amendments would represent about 0.3 percent of annual revenue. 

Figure VII-4: Freight Company Annual Rule Costs vs. Normal Replacement Costs 

$0

$50,000

$100,000

$150,000

$200,000

$250,000

$300,000

$350,000

$400,000

20102011201220132014201520162017201820192020202120222023

Proposed

Existing

Average Normal

Replacment Costs

4. Financial Feasibility for Individual Fleets 

Staff is continuing to evaluate the potential impacts on actual individual fleets and 

industries subject to the regulation. Towards this end, staff plans to present additional 

economic information regarding cash flow analyses, access to capital, and fleets’ “ability 

to pay” to comply with the revised regulation as part of the December 2010 Board 

hearing. 

5. Specific Impacts of Proposed Amendments 

For the next decade the proposed amendments would only require modernization of 

engines that are 20 years old or older, and would exempt about 150,000 lighter trucks 

(less than 26,001 pounds GVWR) from meeting the PM filter requirements. In addition, 
-62-

the proposed amendments would reduce costs for fleets with heavier trucks (GVWR 

greater than 26,000 pounds) by extending the allowable period of retrofit PM filter use 

from four years to eight years and, until 2020, would limit truck replacements to only 

those that have 20 year old or older engines, rather than requiring replacements for 

trucks with engines as new as 12 years old. Below is a description of the significant 

proposed amendments that have the largest potential for cost savings. 

a) Requirements for Lighter Vehicles 

Lighter vehicles with a GVWR 26,000 pounds or less would now be exempt from 

meeting the PM BACT requirements and only vehicles with engines that are 20 years 

old or older would need to be replaced from 2015 to 2020 with a 2010 model year 

engines or having equivalent emissions. This change would eliminate the PM filter 

requirements for about 150,000 lighter trucks and most or all of the costs for up to 

75,000 companies and small businesses with lighter trucks such as plumbers, 

electricians, general contractors, local moving companies, parts suppliers, retail and 

wholesale stores, equipment and supply manufacturers and services providers. 

Additionally, no reporting would be required. The savings attributable to this change in 

requirements for lighter trucks is nearly $1 billion 

b) BACT Compliance Schedule for Heavier Trucks 

The amendments to the existing BACT compliance schedule would now apply only to 

heavier trucks (GVWR greater than 26,000 pounds) with fleets meeting the 

requirements of the schedule still not needing to report. The PM requirements would be 

delayed one year and would only apply to 1998 and newer model years, while at the 

same time applying to fewer vehicles. The replacement requirements would start two 

years later, in 2015, but would only apply to vehicles having 20 year old engines rather 

than 12 year old engines. This change would allow most vehicles that would be 

required to have retrofit PM filters to be able to operate their full useful lives. 

Staff’s proposal would also allow 1997 and older model year engines to be replaced 

when 20 years old or older rather than be retrofit with PM filters. With this change, 

fleets with older trucks would be able to operate their vehicles most or all of their useful 

lives without any regulatory costs and would have a better opportunity to buy used 

replacement trucks that meet the final requirements. The overall cost savings for 

changing the BACT compliance schedule is about $2.3 billion. 

c) Phase-in Option for Small Fleets 

This optional compliance schedule for small fleets with one to three vehicles would 

begin January 1, 2014 but would eliminate the requirement that the fleet upgrade to a 

2004 model year or newer engine prior to installing a PM retrofit. Instead, starting 

January 1, 2014, small fleets would need to demonstrate one vehicle per year is 

equipped with a PM filter, whether it is a retrofit or originally equipped. Fleets that 

already have a truck originally equipped with a PM filter could delay the installation of a 

retrofit on the second vehicle. Small fleets would no longer need to bring more than one 

vehicle into compliance in a single year and could spread out their costs. Delaying the 
-63-

PM requirements for the second and third vehicle until 2015 and 2016 respectively also 

provides small fleets the ability to replace existing vehicles with less expensive used 

vehicles that meet the final requirement or are already equipped with PM filters. Most of 

the cost savings for small fleets comes from delaying truck replacements already 

described as part of the changes to the BACT compliance schedule. The savings 

attributable to this phase-in option are primarily from delayed compliance for the second 

or third truck. 

d) Phase-in Option for Large Fleets 

The phase in option would require a fleet to increase the number of PM filters on their 

vehicles by 30 percent each year from 2012 to 2014, and by 2016 the remaining 

10 percent of the fleet would need to meet the overall BACT schedule requirements. 

This option would allow fleets to decide the order in which vehicles would be retrofit and 

replaced, regardless of their age. This would provide additional flexibility to fleets so 

they may be able to keep older, more expensive or specialized vehicles in their fleet 

longer than would be allowed with the BACT schedule. 

Another change with this option would be to allow fleets with both drayage and nondrayage trucks to include all their vehicles in the phase-in option. This change would 

allow fleets that go to the ports or intermodal rail yards infrequently to count their 

cleaner vehicles in determining compliance and could lower the compliance costs for 

mixed fleets and provide more flexibility for fleets. 

e) Economic Relief for Fleets that have Reduced their Fleet Size 

This provision would offers economic relief for fleets that have reduced their fleet size 

since 2006. The credit would reduce the annual requirements for fleets most affected 

by the recession until January 1, 2016. With this proposal, a fleet would be able to 

reduce its clean-up requirement in a compliance year by subtracting the percentage that 

the fleet has downsized from the annual requirement. A fleet that has 30 percent fewer 

trucks operating would be able to treat three out of ten trucks as compliant until 2016 

and would effectively defer the compliance requirements for the entire fleet by 1 year 

until 2016. The capital investments required in the first five years would be reduced by 

about 30 percent. A fleet that has downsized by 50 percent would reduce the capital 

investments required in the first five years by 50 percent. 

B. Effects of Amendments to the Drayage Truck Regulation 

Similarly, aligning the requirements of the Drayage Truck regulation with the proposed 

amendments to the Truck and Bus regulation would lower costs for drayage truck 

operators by extending the useful life of their already retrofitted trucks an additional 

six years and by eliminating the requirement to modernize to a truck with a 2007 model 

year engine or newer. 

The change to expand the definition of drayage trucks to include class seven tractors 

would also lower costs for some fleets. The existing Truck and Bus regulation already 

requires PM filters on all trucks by 2014 and requires most to have 2004 or newer 
-64-

engines. The inclusion of class 7 tractors would keep the PM requirements in place, but 

would eliminate the requirement to modernize to a truck with a cleaner engine. 

While trucks serving the Ports of Long Beach and the Port of Los Angeles already have 

2007 model year engines or newer through the Clean Ports Program, only about 

23 percent of the 4,200 drayage trucks outside the South Coast are expected to have 

2007 and newer engines by 2014. Staff estimates that the proposed amendment 

eliminating the requirement to upgrade to the 2007 engine by 2014 would save the 

owners of the remaining 77 percent of pre-2007 model year trucks about $29 million in 

replacement costs by reducing the reporting and record keeping period for drayage 

trucks from 10 years to seven years and would result in approximately $13 million in 

savings for the 18,000 truck owners ($270 yearly saving per truck) and the 1,800 motor 

carriers ($4,700 yearly savings per motor carrier) subject to the regulation. 

C. Effects of Amendments to the Tractor-Trailer GHG regulation 

Most of the proposed amendments to the Tractor-Trailer GHG regulation are intended 

to provide additional flexibility to fleets, but are not expected to have a major impact in 

the average cost of the regulation. However, fleets that elect to utilize the proposed 

provision to delay compliance with the low rolling resistance tire requirements would not 

realize the cost savings benefits resulting from the existing regulation. Nevertheless, 

most of the fleets are expected to utilize fuel efficient tires prior to the proposed 

compliance date as the existing tire casings reach their natural end of retread life cycle 

and the tires get replaced with new ones. Thus, the proposed compliance delay with 

the low rolling resistance tires is expected to not have a significant impact on the overall 

cost savings and estimated costs of the existing program. 

D. Impacts on Incentive Funding 

1. Impact of Proposed Amendments on Funding Opportunities 

State incentive funding programs play a complementary role to the state’s regulatory 

emission reduction programs to help meet the state’s SIP requirements and achieve 

California’s air quality goals. ARB’s portfolio of incentive funding and loan assistance 

programs includes the Carl Moyer Program, the Goods Movement Emission Reduction 

Program, Lower Emission School Bus Program, and the AB118 Air Quality 

Improvement Program. 

Funding is currently available for truck and bus replacement, retrofits, and repowering 

that provide early or extra reductions to the regulatory requirements. Eligibility depends 

on several factors, including fleet size, vocation, and the type of vehicle and reduced 

emission technology. The regulation compliance deadlines affect eligibility by defining 

the end of the surplus emission reduction period. In addition, each funding program 

must be consistent with statutory requirements that vary by program. 

In general, the proposed regulatory changes should enable greater funding 

opportunities by allowing more time for applicants to apply for funding before 

compliance dates. Staff will present a summary of potential incentive impacts when the 
-65-

Board considers regulatory changes in December. Staff plans to propose incentive 

program revisions that reflect the Board’s action and direction with other funding 

program changes at a later date, with revisions to funding opportunities for the Carl 

Moyer Program already planed for next year. 

Many federal and state programs are administered by local agencies, so vehicle owners 

should check with their local air quality management district for funding opportunities. 

Some vehicles may have their own specially funded programs based on type and use. 

In addition, funding may be available for technologies such as zero-emission and hybrid 

vehicles that achieve emission reductions beyond those required by regulation. 

2. Access to Funding for Vehicle Owners 

Interested vehicle owners can obtain more information on funding and compliance by 

using any of ARB’s outreach tools including the Truck Stop website at 

www.arb.ca.gov/truckstop, the phone hotline at 866-6DIESEL (866-634-3735), or the 

email address at 8666diesel@arb.ca.gov. 
-66-
-67-

VIII. ALTERNATIVES CONSIDERED 

This chapter discusses alternatives to the proposed amendments to the Truck and Bus, 

Tractor-Trailer GHG, and Drayage Truck regulations.

A. Alternatives Considered to the Truck and Bus Regulation 

Staff considered a number of alternatives instead of the proposed amendments. These 

included making no changes to the regulation, simply modifying the existing 

requirements of the regulation, and establishing clean-up requirements that varied each 

year based on economic indicators. Each of these alternatives was rejected in favor of 

staff’s proposed amendments. 

1. Make No Changes to Regulation 

The current regulation requires 50 percent of trucks to be replaced with 2010 engines to 

achieve substantial NOx emissions reductions originally expected to be needed to meet 

the 2014 PM2.5 federal attainment deadline, and also requires that 100 percent of the 

in-use fleet have PM filters. Staff rejected this proposal for the following reasons: 

• The downturn in the economy has resulted in lower emissions than previously 

anticipated, thereby reducing the overall amount of NOx and PM reductions 

needed by 2014. By not changing the existing regulation, this proposal would 

compel fleets to take actions to achieve emission reductions that are not 

necessary to meet NAAQS or the SIP. 

• This proposal would provide no economic relief to fleets, and does not meet the 

Board’s direction to staff. 

• This proposal would not reduce the overall complexity of the regulation, as 

opposed to staff’s proposed amendments which would make the regulation 

substantially more straightforward to understand. 

2. Simply Modify the Existing Requirements of the Regulation 

Staff considered several alternatives that retained the existing structure of the regulation 

(including all three existing compliance options), but modified the amount of actions 

fleets would have to take each year. 

a) Change existing BACT and Percent Turnover Rates 

Staff considered retaining the existing structure of the regulation and modifying the 

annual compliance requirements for all three compliance options. However, because 

substantial NOx reductions are no longer required by 2014, the structure set up to give 

fleets flexibility to meet NOx and PM requirements at the same time is no longer 

needed. This alternative would not decrease the current complexity of the regulation. 

b) Establish Reduced Requirements for Medium Fleets (4 to 20 Vehicles) 

Staff considered a provision for fleets with less than 40 vehicles that would have 

allowed a one to two year deferral to provide immediate near-term economic relief, but 
-68-

still had all fleets meet the current 2014 requirements. Staff rejected this alternative 

because it would have resulted in high peak year costs and higher overall costs, as 

these fleets would have had to compress all of their retrofits and turnover of 50 percent 

of their fleet in only two years (2013 and 2014). Staff does not believe that this 

alternative provides substantial economic relief when compared to the proposed 

amendments, as staff’s proposal spreads out the costs, decreases peak year costs, and 

provides additional credits for fleets. Also, this alternative would not decrease the 

current complexity of the regulation. 

c) Two Year Delay of the Regulation for All Fleets 

Staff considered a full two year delay of the current regulation for all fleets. Staff 

rejected this alternative because a two year delay of all requirements would fail to meet 

the State’s overall SIP targets by 2014 and would still require a substantial number of 

vehicle replacements by 2016. 

 

3. Establish Requirements that Vary by Economic Indicators 

Staff evaluated the feasibility of modifying the regulation such that its requirements 

would vary based in response to specific economic indicators such as the State’s gross 

domestic product (GDP), unemployment rate, earnings, the consumer price index, 

and/or housing starts. As the selected indicators change, the regulatory requirements 

would change in response. 

This alternative was rejected for two reasons. First, there is no single indicator that 

adequately represents all business sectors or business sizes. The use of any selected 

indicator would either be an advantage to certain sectors over others or could unfairly 

benefit businesses of a certain size over other sizes. In addition, linking regulatory 

requirements to economic indicators creates significant uncertainty in the planning 

process for affected fleets and businesses and would make it more difficult to get 

approvals to make the needed investments in a timely fashion. 

Most economic indicators are not publicly available for 3 to 6 months; therefore, it would 

be difficult to inform fleets of any changes to the compliance requirements in time for 

them to adjust their compliance plans. Fleets would be placed in an awkward situation 

where those who wait to make the needed investments would have an advantage over 

those who plan ahead and later learn the action taken was not needed. If the 

requirement is not reduced as expected, then fleets that did not make the needed 

investments early would have a difficult time getting into compliance on time. Without 

sufficient notice and the ability to project future expenses, strategic planning for 

compliance would no longer be feasible to affected fleets. If the economic indictor was 

used to adjust a compliance requirement at least one year after the data was made 

available to allow fleets time to plan for the needed expenditures, the requirements 

would substantially lag behind the indicator and the requirements would be less 

stringent than needed during a recovery period and would be more stringent after a 

peak when economic relief would be needed the most.
-69-

B. Alternatives Considered to the Drayage Truck Regulation 

Staff analyzed and ultimately rejected two alternatives to the proposed amendments to 

the Drayage Truck regulation. The first alternative considered was to make no changes 

to the regulation. The second alternative considered was to delay the Phase 2 

requirements in the current regulation by only two years, until December 31, 2015. 

1. Make No Changes to the Regulation 

Drayage trucks are required to comply with the current Phase 1 retrofit requirements for 

a level 3 PM filter, as well as ultimately upgrade their vehicles to one having a 2007 

model year or later engine by 2014. However, the downturn in the economy has 

resulted in lower emissions from drayage trucks than previously anticipated. As such, 

economic relief can be provided to drayage truck operators while still maintaining the 

localized diesel PM reductions of the regulation and meeting applicable SIP targets. 

Because this alternative would not provide any economic relief to fleets affected by the 

recession, and would exceed the emission reductions needed to meet applicable SIP 

targets, staff does not believe this alternative is consistent with the Board’s direction. 

Therefore, this alternative was rejected. 

2. Delay Phase 2 Requirements 2 years 

This alternative would delay the Phase 2 regulatory requirements by two years. This 

would result in slightly lower overall costs for the regulation, as fleets’ anticipated costs 

to meet the Phase 2 requirements would simply be shifted back by two years to 

January 1, 2016. While not significant, this reduction in costs would be due to both a 

delay in the regulatory requirements by two years, as well as due to the fact that 

compliant trucks would be two years older (and slightly less expensive to buy by 2016 

rather than by 2014). Staff estimates that the proposed changes to the regulation will 

provide a 30 percent greater cost savings than this alternative. Therefore, this two year 

postponement option would provide less economic relief to drayage truck operators 

compared to the economic relief from staff’s proposed changes. Therefore, this 

alternative was rejected. 

C. Alternatives Considered to the Tractor-Trailer GHG Regulation 

The only alternative considered by staff was to not amend the Tractor-Trailer GHG 

regulation. This alternative was rejected in part because it would not provide any 

additional flexibility to fleets that either missed the optional large fleet compliance 

phase-in registration date or needed to amend their compliance plans. In addition, 

making no changes to the regulation would not provide trailer fleets with guidance 

regarding which aerodynamic equipment modifications would or would not comply with 

the Tractor-Trailer GHG regulation. Finally, making no changes to the regulation could 

result in a significant financial burden on the owners of specific types of trailers, (e.g. 

storage trailers and local-haul trailers) without any corresponding GHG emission 

benefits. 
-70-
-71-

IX. REFERENCES 

ARB, 2000. California Air Resources Board. Risk Reduction Plan to 

Reduce Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles. 

October 2000. 

http://www.arb.ca.gov/diesel/documents/rrpapp.htm

ARB, 2007. California Air Resources Board. Expanded Action Measures to Reduce 

Greenhouse Gas Emissions in California Recommended for Board Consideration. 

October 2007. 

http://www.arb.ca.gov/cc/ccea/meetings/ea_final_report.pdf

ARB, 2008a California Air Resources Board. Climate Change Scoping Plan 

Appendices. Volume I: Supporting Documents and Measure Detail, Appendix C. 

Sacramento: October 2008.

http://www.arb.ca.gov/cc/scopingplan/document/scopingplandocument.htm

ARB, 2008b. California Air Resources Board. Technical Support Document: Proposed 

Regulation for In-Use On-Road Diesel Vehicles. October 2008. 

http://www.arb.ca.gov/regact/2008/truckbus08/tsd.pdf

ARB, 2008c. California Air Resources Board. Initial Statement of Reasons for Proposed 

Rulemaking: Proposed Regulation for In-Use On-Road Diesel Vehicles. October 2008. 

http://www.arb.ca.gov/regact/2008/truckbus08/tbisor.pdf

ARB, 2009a, California Air Resources Board. The Effect of the Recession on Trucking 

Emissions. Presentation at the Board Hearing, December 9, 2009. 

http://www.arb.ca.gov/board/books/2009/120909/09-10-8pres.pdf

ARB, 2009b. California Air Resources Board. The California Almanac of Emissions and 

Air Quality. 2009 Edition. 

http://www.arb.ca.gov/aqd/almanac/almanac09/almanac09.htm

ARB, 2010a. California Air Resources Board. Estimate of Premature Deaths Associated 

with Fine Particle Pollution (PM2.5) in California Using a U.S. Environmental Protection 

Agency Methodology. August 2010. 

http://www.arb.ca.gov/research/health/pm-mort/pm-report_2010.pdf

ARB, 2010b. California Air Resources Board. Proposed Amendments to the Regulation 

for In-Use Off-Road Diesel-Fueled Fleets and Off-Road Large Spark Ignition Engine 

Fleet Requirements. October 2010. 

Chow et al., 2010. Chow J.C.; Watson J.G.; Lowenthal D.H.; Chen L.W.; Motallebi N., 

(2010). Black and organic carbon emission inventories: review and application to 

California. J. Air Waite Manag Assoc. Apr;60(4):497-507. 
-72-

Hadley et al., 2010. Hadley, O. L.; Corrigan, C. E.; Kirchstetter, T. W.; Cliff, S. S.; and 

Ramanathan, V. (2010). Measured black carbon deposition on the Sierra Nevada snow 

pack and implication for snow pack retreat, Atmos. Chem. Phys., 10, 7505-7513. 

Hansen et al., 2007. Hansen, J.; Sato, M.; Kharecha, P.; Russell, G.; Lea, D. W.; 

Siddall, M. (2007). Climate change and trace gases. Philos. Trans. R. Soc. London, Ser. 

A., 365 (1856), 1925–1954. 

Krewski et al., 2009. Krewski D.; Jerrett M.; Burnett R.T.; Ma R.; Hughes E.; Shi Y.; 

Turner M.C.; Pope C.A. III; Thurston G.; Calle E.E.; Thun M.J. 2009. Extended FollowUp and Spatial Analysis of the American Cancer Society Study Linking Particulate Air 

Pollution and Mortality. HEI Research Report 140. Health Effects Institute, Boston, MA. 

Núñez, 2006. (Núñez, Chapter 488, Statutes of 2006) California Global Warming 

Solutions Act of 2006. September 27, 2006. 

http://www.leginfo.ca.gov/pub/05-06/bill/asm/ab_0001-

0050/ab_32_bill_20060927_chaptered.pdf

Ramanathan, V.; Carmichael, G. (2008). Global and regional climate changes due to 

black carbon. Nature Geoscience 156, 221-227. 

U.S. EPA, 2009. U.S. Environmental Protection Agency. Integrated Science 

Assessment for PM (Final Report). 

http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_2007_isa.html 

U.S. EPA, 2010. U.S. Environmental Protection Agency. Quantitative Health Risk 

Assessment for Particulate Matter - Final Report. 

http://www.epa.gov/ttnnaaqs/standards/pm/s_pm_2007_risk.html