State of California 

California Environmental Protection Agency 

AIR RESOURCES BOARD 

PUBLIC HEARING TO CONSIDER REQUIREMENTS TO REDUCE IDLING 

EMISSIONS FROM NEW AND IN-USE TRUCKS, BEGINNING IN 2008 

FINAL STATEMENT OF REASONS 

August 2006 
- 2 - 

State of California 

AIR RESOURCES BOARD 

Final Statement of Reasons for Rulemaking, 

Including Summary of Comments and Agency Response 

PUBLIC HEARING TO CONSIDER REQUIREMENTS TO REDUCE IDLING 

EMISSIONS FROM NEW AND IN-USE TRUCKS, BEGINNING IN 2008 

Public Hearing Date: October 20, 2005 

Agenda Item No.: 05-10-3 

I. General 

The Staff Report: Initial Statement of Reasons for Rulemaking (“Staff Report”), 

entitled “Notice of Public Hearing to Consider Requirements to Reduce Idling 

Emissions from New and In-use Trucks, Beginning in 2008,” released September 

1, 2005 is incorporated by reference herein. 

This rulemaking by the Air Resources Board (ARB or Board) consists of the three 

major components: 

The first component primarily requires manufacturers of new California 

certified 2008 and subsequent model-year diesel engines installed in trucks 

with a gross vehicle weight rating greater than 14,000 pounds to either 

incorporate a system that automatically shuts the engine down after five 

minutes of continuous idling or to certify the engines to an oxides of nitrogen 

(NOx) idling emission standard of 30 grams per hour. This component of the 

rulemaking is hereinafter referred to as the “new engine requirements” of this 

rulemaking. 

The second component primarily eliminates an existing exemption for sleeper 

berth equipped trucks (and therefore requires that they must comply with) the 

anti-idling requirements of title 13, California Code of Regulations (CCR) 

section 2485. This component of the rulemaking is hereinafter referred to as 

the “in-use requirements” of this rulemaking. 

The third component of this rulemaking establishes emissions performance 

requirements for devices that truck operators may elect to utilize to provide 

power for climate control, engine heating, or electrical power purposes that 

would otherwise be supplied by idling the vehicle’s main engine. This 

component applies to both the new engine and the in-use requirements 

On September 2, 2005, ARB published a notice for an October 20, 2005 public 

hearing to consider the proposed amendments. A Staff Report: Initial Statement of 

Reasons (the Staff Report) was also made available for public review and comment 
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beginning September 2, 2005. The Staff Report provides the rationale for the 

proposed amendments. The text of the proposed amendments to title 13, California 

Code of Regulations (CCR) sections 1956.8, 2404, 2424, 2425 and 2485 and the 

test procedure incorporated by reference therein, “California Exhaust Emission 

Standards and Test Procedures for 2004 and Subsequent Model Heavy-Duty Diesel 

Engines and Vehicles” was included as an Appendix to the Staff Report. These 

documents were also posted on the ARB’s Internet site for the rulemaking at: 

http://www.arb.ca.gov/regact/hdvidle/hdvidle.htm

On October 20, 2005 the Air Resources Board (the “Board” or the “ARB”) conducted 

the public hearing and received oral and written comments. At the conclusion of the 

hearing, the Board adopted Resolution 05-55, in which it approved the proposed 

amendments with the following significant modifications: 

(1) modifying the provision (in Title 13, CCR section 1956.8) allowing the new 

engine shutdown system to be overridden during power take off-mode 

operations so that the override switch is not required to fail in the “off” position 

to accommodate safety concerns. 

(2) clarify that manufacturers using battery powered auxiliary power systems 

(APSs), a power inverter/charger for on-shore power, or an electric 

infrastructure or comparably clean technology need not seek and obtain 

advance Executive Officer approval before using such systems. 

These modifications had been suggested by staff in a two-page document entitled 

“Staff’s Suggested Modifications to Original Proposal” that was distributed at the 

hearing and was Attachment C to Resolution 05-55. Attachment C showed excerpts 

of the originally proposed amendments to the regulations and incorporated 

documents, with the text of all suggested modifications clearly identified. Other 

modifications were suggested by commenters and approved by the Board during the 

hearing: (1) technologies utilizing electrical shore power or comparably clean 

emission technologies would be allowed as options to comply with the in-use idling 

regulations set forth in section 2485 of title 13, California Code of Regulations, (2) 

military tactical vehicles would be exempted from the proposed amendments to 

sections 1956.8, 2404, 2424, 2425 of title 13, California Code of Regulations, and 

(3) the current exemption applicable to military tactical vehicles in section 2485 of 

title 13, California Code of Regulations would be clarified to also exempt operational 

modes such as training, testing, and deployment. 

In accordance with section 11346.8 of the Government Code, the Resolution 

directed the Executive Officer to incorporate the modifications into the proposed 

regulatory text, with such other conforming modifications and technical amendments 

as may be appropriate, and to make the modified text available for a supplemental 

comment period of at least 15 days. She was then directed either to adopt the 

amendments with such additional modifications as may be appropriate in light of the 

comments received, or to present the regulations to the Board for further 

consideration if warranted in light of the comments. The Resolution and its 
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Attachment C are available at ARB’s Internet web page for this rulemaking: 

http://www.arb.ca.gov/regact/hdvidle/hdvidle.htm 

Subsequent to the hearing, staff identified a number of additional, primarily technical 

modifications that are appropriate to make the amended regulations work as 

effectively as possible. The most significant of these post-hearing modifications 

were: (1) allowing the engine shutdown system to be overridden during exhaust 

emission control device regeneration or maintenance periods, or if servicing or 

maintenance of the engine requires extended idling, (2) clarifying that the engine 

shutdown system requirements do not apply to emergency vehicles or to 

medium-duty vehicles, (3) clarifying in the test procedures portion of the rulemaking 

that for compliance with the optional NOx idling standard, the average NOx 

emissions of each mode of the supplemental NOx idling test procedure should not 

exceed the optional NOx standard, and (4) modifying the definition of auxiliary power 

system (APS) in the ATCM portion of the rulemaking to extend the availability of 

compliant APSs as a compliance alternative to buses and other non-truck 

commercial vehicles. These post-hearing modifications were incorporated into the 

text of the proposed regulations and incorporated documents, along with the 

modifications approved by the Board at the hearing.

The text of all the modifications to the originally proposed amendments to the 

regulations and incorporated documents was made available for a supplemental 

15-day comment period by issuance of a “Notice of Public Availability of Modified 

Text.” This Notice, a copy of the Resolution 05-55, and the Attachment C document 

entitled “Staff’s Suggested Modifications to Original Proposal,” were mailed on June 

28, 2006 to all parties identified in section 44(a), title 1, CCR, and to other persons 

generally interested in the ARB’s rulemaking concerning requirements applicable to 

heavy-duty diesel engines/vehicles, small off-road engines, and cab comfort 

devices. The “Notice of Public Availability of Modified Text” listed the ARB internet 

site from which interested parties could obtain the complete text of the incorporated 

documents that would be affected by the modifications to the original proposal, with 

all of the modifications clearly indicated. These documents were also published on 

ARB’s Internet web page for this rulemaking 

http://www.arb.ca.gov/regact/hdvidle/hdvidle.htm on June 27, 2006. Five written 

comments were received during the 15-day comment period. 

After considering the comments received during the 15-day comment period, the 

Executive Officer issued Executive Order R-06-003, adopting the amendments to 

Title 13, CCR and to the incorporated documents. 

This Final Statement of Reasons (FSOR) updates the Staff Report by identifying and 

providing the rationale for the modifications made to the originally proposed 

regulatory texts, including nonsubstantial modifications and clarifications made after 

the close of the 15-day comment period. The FSOR also contains a summary of the 

comments received by the Board on the proposed regulatory amendments and 

ARB’s responses to those comments.
- 5 - 

Incorporation of Test Procedures and Federal Regulations. The amended test 

procedures are incorporated by reference in Title 13, CCR sections 1956.8 and 

2485. The test procedures in turn incorporate certification test procedures adopted 

by United States Environmental Protection Agency (U.S. EPA) and are contained in 

Title 40, Code of Federal Regulations (CFR), Part 86.

Title 13, CCR sections 1956.8 and 2485 identify the incorporated ARB documents 

by title and date. The ARB documents are readily available from the ARB upon 

request and were made available in the context of this rulemaking in the manner 

specified in Government Code Section 11346.5(b). The CFR is published by the 

Office of the Federal Register, National Archives and Records Administration, and is 

therefore reasonably available to the affected public from a commonly known 

source.

The test procedures are incorporated by reference because it would be impractical 

to print them in the CCR. Existing ARB administrative practice has been to have the 

test procedures incorporated by reference rather than printed in the CCR because 

these procedures are highly technical and complex. They include the “nuts and 

bolts” engineering protocols and laboratory practices required for certification of 

regulated engines and equipment, and have a very limited audience. Because ARB 

has never printed complete test procedures in the CCR, the affected public is 

accustomed to the incorporation format utilized therein. The ARB’s test procedures 

as a whole are extensive and it would be both cumbersome and expensive to print 

these lengthy, technically complex procedures with a limited audience in the CCR. 

Printing portions of the ARB’s test procedures that are incorporated by reference 

would be unnecessarily confusing to the affected public. 

The test procedures incorporate portions of the CFR because the ARB requirements 

are substantially based on the federal regulations. Manufacturers typically certify 

vehicles and engines to a version of the federal emission standards and test 

procedures that have been modified by state requirements. Incorporation of the 

federal regulations by reference makes it easier for manufacturers to know when the 

two sets of requirements are identical and when they differ. Each of the 

incorporated CFR provisions is identified by date in ARB’s test procedure 

documents.

Fiscal Impacts. The Board has determined that this regulatory action will not create 

create costs or savings, as defined in Government Code section 11346.5(a)(6), to 

any state agency or in federal funding to the state, costs or mandate to any local 

agency or school district whether or not reimbursable by the state pursuant to part 7 

(commencing with section 17500), Division 4, title 2 of the Government Code, or 

other nondiscretionary costs or savings to state or local agencies. 

Consideration of Alternatives. The amendments and new regulatory language 

proposed in this rulemaking were the result of extensive discussions and meetings 

involving staff and the affected engine, truck, and cab comfort device manufacturers, 

trucking business associations, and others. In the Staff Report, released and made 
- 6 - 

available to the public on September 2, 2005, staff evaluated and ultimately rejected 

four potential alternatives which included: (1) solely relying on educational and 

incentive programs to encourage sleeper truck owners and operators to voluntarily

reduce idling and use cab comfort devices, (2) in lieu of engine shutdown systems, 

require engine manufacturers to either certify engines to a low NOx idle emission 

standard (30 g/bhp-hr) or to install a compliant APS on all sleeper berth equipped 

trucks sold in California, and also eliminate the sleeper truck exemption from the 

in-use idling restriction requirement, (3) require engine shutdown systems and only 

allow alternative cab comfort devices using zero emitting technologies such as 

battery electric APSs, fuel cell APSs, thermal storage systems, truck stop 

electrification, or any other zero emitting technology, and also eliminate the sleeper 

truck exemption from the in-use idling restriction requirement, and (4) pursue 

requirements that only regulate new 2008 and subsequent model-year trucks and do 

not modify the existing exemption for sleeper trucks in the in-use idling restriction 

requirement. 

After the Staff Report was released, the Engine Manufacturers Association (EMA) 

transmitted a proposal to staff, that new engines in all 50 states would be equipped 

with a password protected, programmable engine shutdown system that would 

activate after the engine idled five minutes, but that could also be deactivated by the 

truck owner or owner-operator. In addition, all sleeper trucks would continue to be 

exempted from the in-use idling restriction requirement. EMA also suggested that if 

ARB did not accept the proposal to maintain the exemption of sleeper trucks, ARB 

should provide another option that phased out that exemption according to date of 

manufacture, or by using a percentage-of-fleet approach, with continued exemption 

of 2010 and newer model year trucks. ARB rejected this proposal because it would 

not be as effective in reducing emissions and in enforcing the idling restriction 

requirements as the proposed adopted amendments. 

For the reasons set forth in the Staff Report, and based on staff’s comments and 

responses at the hearing and in this FSOR, the Board has determined that no 

alternative considered by the agency or brought to the attention of the agency would 

be more effective in carrying out the purpose for which the regulatory action was 

proposed or would be as effective and less burdensome to affected private persons 

than the action taken by the Board. 

II. MODIFICATIONS TO THE ORIGINAL PROPOSAL 

A. MODIFICATIONS APPROVED BY THE BOARD AT THE PUBLIC HEARING 

AND THAT WERE IDENTIFIED IN THE 15-DAY PUBLIC COMMENT PERIOD 

As previously discussed, during the October 20, 2005 public hearing, the Board 

approved the adoption of the originally proposed amendments with several 

modifications. The modifications approved by the Board and those identified 

subsequent to the Board hearing were explained in detail in the Notice of Public 

Availability of Modified Text that was issued for a 15-day public comment period that 
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began on June 28, 2006, and ended on July 13, 2006. In order to provide a 

complete FSOR for this rulemaking, these modifications and clarifications are also 

described below by section number. 

1. Modifications to Title 13, CCR, Section 1956.8 

Override Switch Setting During Power Take Off Mode 

The provision allowing the engine shutdown system to be overridden during power 

take-off operation was modified to remove the requirement that the override switch 

be designed to fail in the “off” setting. This change was made to accommodate 

safety concerns. (Section 1956.8(a)(6)(A)2.a) 

Exempting Military Tactical Vehicles, Authorized Emergency Vehicles, and 

Medium-Duty Vehicles from the Engine Shutdown System Requirement

Paragraph (a)(6)(B) was modified to explicitly exempt military tactical vehicles, 

authorized emergency vehicles, and medium-duty vehicles from the engine 

shutdown system requirement. The modifications simply clarify the applicability of 

the requirement since Title 13, CCR, Section 1905, and California Vehicle Code 

Section 27156.2 already exempt military tactical vehicles and authorized emergency 

vehicles, respectively, from any motor vehicle emission control device requirements. 

With respect to medium-duty vehicles, staff clearly stated in its presentation to the 

Board that this requirement only applied to heavy-duty diesel engines installed in 

vehicles with a gross vehicle weight rating greater than 14,000 pounds. However, 

this was not explicitly stated in the original proposed regulatory text. The 

modifications remedy this oversight. 

Shutdown System Override for Exhaust Emission Control Device Regeneration

Section 1956.8(a)(6)(A)2.c adds a new provision that allows the engine shutdown 

system to be overridden during periods when the vehicle’s exhaust emission control 

device (e.g., diesel particulate matter trap) requires regeneration during periods of 

engine idling and the override is needed to prevent aftertreatment or engine 

damage. The engine shutdown system may be overridden for no longer than 30 

minutes during regeneration periods. Regeneration events requiring longer than 30 

minutes are subject to advance Executive Officer approval. This modification also 

requires that any override system incorporate a light on the vehicle’s dashboard to 

indicate that the exhaust emission control device is regenerating during idling 

conditions. 
- 8 - 

Shutdown System Override for Engine Servicing, Maintenance or Diagnosis 

Section 1956.8(a)(6)(A)2.d includes a provision allowing the engine shutdown 

system to be overriden for up to 60 minutes if required for engine servicing, 

maintenance, or diagnostic routines that require idling the truck engine for more than 

5 minutes. This provision requires the engine shutdown system be temporarily 

deactivated only with the use of a diagnostic scan tool to prevent unauthorized 

overrides of the shutdown system. 

Engine Emissions when Certifying to the Optional Idling Standard1

Paragraph (a)(6)(C) was modified to clarify how a manufacturer may determine 

whether or not emissions of carbon monoxide (CO), non-methane hydrocarbons 

(NMHC), and particulate matter (PM) are adversely affected when certifying an 

engine to the optional oxides of nitrogen (NOx) idling standard. The modification 

states that a manufacturer certifying an engine to the optional NOx standard may 

compare emissions of CO, NMHC, and PM from the supplemental NOx idling test 

procedure to corresponding emissions from the idle mode of the supplemental 

steady state cycle (European Stationary Cycle) and/or idle portions of the transient 

test cycle (the Federal Test Procedure). With approval from the Executive Officer, a 

manufacturer may also use other methods of ensuring emissions are not adversely 

affected in meeting the optional NOx standard. In addition, to avoid confusion with 

the term “supplemental steady state test cycle” (which refers to the European 

Stationary Cycle), the term “supplemental steady state test procedure” (which 

referred to the optional NOx standard certification test cycle) has been changed to 

“supplemental NOx idling test procedure.” 

Incorporate Revisions into Applicable Test Procedure Section

Paragraph (b) specifies by reference the proposed revised test procedures 

applicable to heavy-duty diesel engines and vehicles. This paragraph was 

inadvertently left out from the original proposed text of the regulation. The 

modification remedies this oversight. 

Correction of Minor Oversight

Subsequent to the hearing, staff realized it had inadvertently omitted the phrase 

“reference in subsection (b)” to subparagraph (a)(6)(C) of section 1956.8, which 

specifies vehicle label specifications incorporated by reference into the engine 

shutdown system requirements. The modification corrects this oversight. 

 

1

 This modification has itself been revised by nonsubstantive changes subsequent to the close of the 15-day 

public comment period. The specific nonsubstantive changes are described in detail below in section II.B of 

this FSOR, but for purposes of this footnote, the most pertinent change is that the 15-day notice referred to 

reactive organic gas (ROG) emissions but ARB’s exhaust emission standards applicable to heavy-duty diesel 

engines only specify non-methane hydrocarbon (NMHC) levels, so this modification has been revised 

accordingly. 
- 9 - 

2. Modifications to the “California Exhaust Emission Standards and Test 

Procedures for 2004 and Subsequent Model Heavy-Duty Diesel 

Engines” 

Label Location and Attachment Requirement

Paragraph 35.B.4.3.1 of Part I, Subpart A, was modified to clarify that the vehicle 

label for an engine certified to the optional NOx idling emission standard or equipped 

with a certified/verified APS should be affixed on the designated location on the 

exterior area of the hood. 

Label Application

Paragraph 35.B.4.5 of Part I, Subpart A, was modified to add truck manufacturers as 

possible installers of labels for engines certified to the optional NOx idling standard 

or for compliant diesel-fueled auxiliary power systems (APS). Originally, the text 

included only dealers and distributors as potential installers of labels. 

Compliance with the Optional NOx Idling Emission Standard 

This modification clarifies that to demonstrate compliance with the optional NOx 

idling emission standard, the calculated average NOx emissions of each mode of the 

supplemental NOx idling test procedure may not exceed the optional NOx idling 

standard of 30 grams per hour. (Part II Test Procedures, Subpart N, 86.1360-2007, 

subsection B.4.2.3) 

3. Modifications to Title 13, CCR Section 2485 

Exempting Military Tactical Vehicles from In-Use Idling Requirement

Paragraph (d)(2)(K) was modified to clarify that the current exemption of military 

tactical vehicles from the in-use idling requirement also encompasses operational 

modes including training, testing, and deployment. 

Use of On-Shore Electrical Power or Equivalent Technologies

Paragraph (c)(3)(C) was modified to clarify that technologies utilizing on-shore 

electrical power or comparably clean emission technologies will be allowed as 

options to comply with the in-use idling regulations. 
- 10 - 

Battery Powered APS and Electric Infrastructure Provisions

Paragraph (c)(3)(C) was modified to clarify that a manufacturer using a battery 

powered APS, fuel cell APS, power inverter/charger for on-shore electrical power, or 

an electric infrastructure or comparably clean technology is not required to seek and 

receive advance Executive Officer approval before using such alternative 

technology. Attachment C to Resolution 05-55 does not explicitly mention fuel cell 

APSs as an equivalently clean technology, but subsequent to the hearing, staff 

determined that fuel cell APSs are within the category of comparably clean 

technologies that should also not require advance Executive Officer approval. 

Coordinating Exemption for Aftertreatment System Regeneration or Maintenance 

Provision with Title 13 CCR Section 1956.8(a)(6)(A)2.c

Paragraph (d)(2)(G) was modified to clarify that idling occurring during the override 

provisions in Title 13, CCR, Section 1956.8(a)(6)(A)2.c for exhaust aftertreatment 

system regeneration or maintenance, as indicated by the required dashboard 

indicator light, is also exempted from the 5 minute in-use idling restriction. This 

clarification is needed to maintain consistency between the new engine and in-use 

components of the regulation. 

Expanding Definition of APS to Other Classes of Vehicles 

The definition for APS was expanded to include vehicles other than sleeper berth 

equipped trucks that might wish to utilize a compliant APS as an alternative to idling 

their main engines. The definition of an APS (Section 2485(h)) was therefore 

amended to allow non-truck commercial vehicles (e.g., buses) to utilize compliant 

APSs. 

B. MODIFICATIONS MADE SUBSEQUENT TO THE 15-DAY PUBLIC 

COMMENT PERIOD 

During the 15-day public comment period, the Engine Manufacturers Association 

(EMA) submitted comments that specified inadvertent mistakes by staff, and that 

requested clarification of issues related to the test procedures for the optional NOx 

idling emission standard. Staff has reviewed and agrees with these comments, and 

has made changes to accommodate them. Staff has also discovered an oversight in 

the test procedures for the optional NOx idling emission standard and has modified 

them to correct the oversight. Each of these modifications constitutes a 

nonsubstantial change to the regulatory text because, as described in greater detail 

below, each modification clarifies the requirements or conditions as set forth in the 

original text (or in the original text as modified in the Notice of Public Availability of 

Modified Text) and does not materially alter those requirements or conditions. 
- 11 - 

1. Substitute NMHC for ROG in Optional NOx Idling Emission Standard 

 Regulation and Test Procedures 

EMA points out that the regulatory text and test procedures relating to the optional 

NOx idling emission standard use the term reactive organic gases (ROG), but that 

the regulated species for heavy-duty engines is non-methane hydrocarbons 

(NMHC). Staff agrees. ARB’s heavy-duty diesel engine exhaust emission 

standards for hydrocarbon emissions only specify non-methane hydrocarbon 

(NMHC) levels, and this is widely known by the regulated community. The staff has 

therefore accordingly modified the regulation and test procedures. 

a. Title 13, CCR Section 1956.8(a)(6)(C) 

Each of the three citations to ROG has been replaced by the term NMHC. 

b. California Exhaust Emission Standards and Test Procedures for 2004 

and Subsequent Model Heavy-Duty Diesel Engines and Vehicles 

Part I.A.11.B.6.3 

Each of the three prior citations to ROG has been replaced by the term 

NMHC. 

2. Substitute “or” for “and/or” in the Optional NOx Idling Emission 

 Standard Regulation and Test Procedures 

EMA states that the regulation and test procedure requires manufacturers certifying 

engines to the optional NOx idling emission standard to compare emissions 

generated during the supplemental NOx idling test procedure to emissions 

generated during the idle mode of the supplemental steady-state test “and/or” during 

the idle portions of the transient test cycle. EMA states the usage of the “and/or” 

term is ambiguous since it can be interpreted either as a conjunctive or a disjunctive 

term, or both. 

Staff’s intent in drafting this provision was to allow a manufacturer to choose which 

test cycle it wanted to use for comparison to the supplemental NOx idling test 

procedure- either the idle mode of the supplemental steady-state test, the idle 

portion of the transient test cycle, or another test procedure, subject to advance 

Executive Officer approval. Staff’s understanding is that the term “and/or” is 

interpreted as a disjunctive term, but is amending the regulation and test procedure 

by substituting “or” for “and/or” to eliminate any possibility of confusion. 

 

a. Title 13, CCR Section 1956.8(a)(6)(C) 

The term “and/or” in the fourth sentence has been replaced by the term “or”. 

b. California Exhaust Emission Standards and Test Procedures for 2004 

and Subsequent Model Heavy-Duty Diesel Engines and Vehicles 

Part I.A.11.B.6.3 

The term “and/or” in the fourth sentence has been replaced by the term “or”. 
- 12 - 

 

3. Clarify Engine Torque Tolerances Specified by the Supplemental NOx Idling 

Test Procedure 

EMA states that the supplemental NOx idling test procedure requires a manufacturer 

to maintain the test engine’s torque within +/- 2% of the target load level, that this 

specification is infeasible at the loads represented by the test modes, and 

recommends instead that the torque tolerance be set at +/- 2% of the maximum 

torque of the engine. 

Staff intended to specify a torque tolerance consistent with that specified in the U.S. 

EPA’s heavy-duty diesel engine test procedures, which requires that torque be 

maintained within +/- 2% of maximum torque of the engine at that test speed. Staff 

has accordingly modified the test procedure to expressly reflect its intent. 

a. California Exhaust Emission Standards and Test Procedures for 2004 

and Subsequent Model Heavy-Duty Diesel Engines and Vehicles 

Part II.N.86.1360-2007.B.4.2.2 

The last sentence in this section is amended by inserting “of the maximum 

torque at the test speed.” to clarify staff’s intent that the torque tolerance is 

fully consistent that specified in the U.S. EPA’s heavy-duty diesel engine test 

procedures. 

4. Clarification that Temperature Stability for Supplemental NOx Idling Test 

Procedure is Determined by Engine Coolant Temperature 

The supplemental NOx idling test procedure specifies that engine emissions must be 

measured only after temperature stability is attained. The procedure defines 

temperature stability “as the point at which the engine coolant is within 2% of its 

mean value for at least 2 minutes.” Although it is apparent that it is in fact the 

temperature of the engine coolant that must be measured to determine temperature 

stability, the term “temperature” was inadvertently omitted from the test requirements 

section of the supplemental NOx idling test procedure. Staff is therefore modifying 

the test procedure to expressly clarify that the engine coolant temperature is the 

parameter that determines temperature stability, and that the reference to thermostat 

is to the engine’s thermostat. 

a. California Exhaust Emission Standards and Test Procedures for 2004 

and Subsequent Model Heavy-Duty Diesel Engines and Vehicles 

(i)Part II.N.86.1360-2007.B.4.2.1(a), Part II.N.86.1360-2007.B.4.2.2 

Insert the term “temperature” immediately following the term “engine coolant” 

in the third sentence of Part II.N.86.1360-2007.B.4.2.1.(a), and in the third 

and sixth sentences of Part II.N.86.1360-2007.B.4.2.2. 
- 13 - 

 

(ii) Part II.N.86.1360-2007.B.4.2.1(b) 

 

 Insert the term “engine” immediately prior to the term “thermostat.” 

III. SUMMARY OF COMMENTS AND AGENCY RESPONSE 

The ARB received written and oral comments during the 45-day comment period in 

response to the September 2, 2005 public hearing notice. Written comments were 

also received during the 15-day comment period in response to the notice of 

proposed modified text made available for comment on June 28, 2006. Listed below 

are persons and organizations that submitted comments. 

During the 45-day comment period, the Board received written comments from: 

 Name and Affiliation (If Any) Written Comment

Date Received 

1 John Goodrich29/16/2005 

2 Larry Green, Sacramento Metropolitan Air 

Quality Management District (SMAQMD) 

9/16/2005 

3 John W. Duerr, 

Detroit Diesel Corporation (DDC) 

10/14/2005 

4 J. R. Mandel and Timothy French, 

Engine Manufacturers Association (EMA) 

10/14/2005 

5 David L. Modisette, California Electric 

Transportation Coalition (CalETC) 

10/14/2005 

6 Schuyler Kennedy 10/5/2005 

7 Irvin Dawid 10/14/2005 

8 Karla Capers 10/7/2005 

9 Stan and Jeanie Haye 10/17/2005 

10 Arthur Unger 10/17/2005 

11 Rex Greer, Pony Pack, Inc. 10/19/2005 

12 David A. Piech, International Truck & Engines 

Corporation (International) 

10/19/2005 

13 California Trucking Association (CTA) 10/19/2005

 

2

 Mr. Goodrich’s comment was not specifically directed at the proposed amendments or to the procedures used 

by ARB in proposing or adopting the proposed amendments. Specifically, Mr. Goodrich’s comment was 

directed at new diesel passenger cars operating on clean diesel fuel. Because this rulemaking only applies to 

new and in-use heavy-duty diesel vehicles, the comment is beyond the scope of the rulemaking. 
- 14 - 

14 Frank Love, Love’s Travel Stops & Country 

Stores (Love’s Travel Stops)) 

10/19/2005 

15 Lisa Mullings, NATSO, Inc. (NATSO) [National 

Trade Association representing truckstops and 

travel plazas] 

10/19/2005 

16 Jack P. Broadbent, Bay Area Air Quality 

Management District (BAAQMD) 

10/19/2005 

17 David Everhart 

IdleAire Technologies Corporation (IdleAire) 

10/19/2005 

18 Rich Wagner & Bob Jorgensen, 

Cummins, Inc. (Cummins) 

10/19/2005 

19 Lola Ungar 10/19/2005 

20 Marcie Brown 10/19/2005 

21 Allen Lilleberg 10/19/2005 

22 One written comment was submitted on 

behalf of the following organizations and 

public citizens: 

10/19/2006 

Don Anair, Union of Concerned Scientists 

Kathryn Phillips, California Clean Air for Life 

Campaign Environmental Defense 

David Lighthall, Ph.D. 

Relational Culture Institute 

Karen G. Pierce, Bayview Hunters Point 

Community Advocates 

Diane Bailey, Natural Resources Defense 

Council 

Bonnie Holmes-Gen, American Lung 

Association of California 

Bill Magavern, Sierra Club California 

Brian Beveridge, West Oakland Environmental 

Indicators Project 

David Schonbrunn, Transportation Solutions 

Defense and Education Fund 

Teri Shore, Bluewater Network, 

A division of Friends of the Earth 

Todd Campbell, 

Coalition for Clean Air 

Tiffany Schauer, Our Children’s Earth 

Foundation 

Anne Kelsey Lamb, Regional Asthma 

Management & Prevention (RAMP) Initiative 
- 15 - 

Joseph K. Lyou, Ph.D., California 

Environmental Rights Alliance 

Martha Dina Arguello, Physicians for Social 

Responsibility – Los Angeles 

Luis Cabrales, Residents of Pico Rivera for 

Environmental Justice 

Melissa Guerrero 

South Gate Resident 

Lynn Devine, (American Lung Association of 

California) 

Craig Jones, MD, (University of Southern 

California Medical Center, Division of Allergy 

and Immunology), 

California Asthma Partners 

Linda Weiner, Bay Area Clean Air Task Force 

(BACATF) 

Susan Frank, Kirsch Foundation 

Harold J. Farber, MD, FAAP, FCCP, Vallejo, 

CA 

Carolina Simunovic 

Fresno Metro Ministry 

Alise Cappel, Environmental Law Foundation 

(ELF) 

Rosenda Mataka, 

Grayson Neighborhood Council 

V. John White, Center for Energy Efficiency 

and Renewable Technologies 

23 Sue Chiang 10/20/2005 

At the October 20, 2005, Board meeting, the ARB received the following written or 

oral comments: 

 

Name and Affiliation (If Any) 

Written 

Comment 

(Date Received)

Oral 

Testimony

1 Dawn Friest 

Engine Manufacturers Association (EMA) 

10/14/2005 

(#4 above) 

YES

2 Will Schaefer, Robert M. Clarke 

Truck Manufacturers Association (TMA) 

10/20/2005 YES
- 16 - 

3 Mike Tunnell 

American Trucking Association (ATA) 

10/20/2005 YES

4 Staci Heaton 

California Trucking Association (CTA) 

10/19/2005 

(#13 above) 

YES

5 Randal Friedman 

U.S. Department of Defense (U.S. DOD) 

NO YES

6 Jason Vega 

California Council for Environmental and 

Economic Balance (CCEEB) 

NO YES

7 Rolf Lichtner, 

Webasto Product, North America, Inc 

NO YES 

8 David Everhart 

IdleAire Technologies Corporation (IdleAire) 

NO YES

9 John Fahrenbach 

IdleAire Technologies Corporation (IdleAire) 

NO YES

10 David Modisette, California Electric 

Transportation Coalition (CalETC) 

10/14/2005 

(#5 above) 

YES 

11 Warner Harris, Coval H2 Partners. LLC 10/20/2005 YES 

12 Rex Greer, Pony Pack, Inc. 10/19/2005 

(#11 above) 

YES

13 Peter Rooney, Pony Pack, Inc. NO YES

14 Andrea Samulon, Pacific Institute NO YES 

15 Diane Bailey, NRDC 10/19/2005 

(#22 above) 

YES 

16 Karen G. Pierce 

Ditching Dirty Diesel Collaborative 

NO YES 

17 Bonnie Holmes-Gen, American Lung 

Association of California 

10/19/2005 

(#22 above) 

YES

18 Don Anair, Union of Concerned Scientists 10/19/2005 

(#22 above) 

YES 

19 Wayne Lorentzen, California National Guard 

(CNG) 

10/20/2005 YES 

20 Bill Magavern, Sierra Club of California NO YES
- 17 - 

During the 15-day comment period, the ARB received the following written 

comments: 

 Name and Affiliation (If Any) Written Comment

Date Received 

1 Theresa Acerro306/28/2006 

2 Gerald Orcholski4 07/06/2006 

3 Vinu Arumugham 07/09/2006 

4 Dawn Friest 

Engine Manufacturers Association (EMA) 

07/13/2006 

5 Robert Clarke 

Truck Manufacturers Association (TMA)5

07/13/2006 

Set forth below is a summary of each objection or recommendation made regarding 

the specific regulatory action proposed, together with an explanation of how the 

proposed action was changed to accommodate each objection or recommendation, 

or the reasons for making no change. The comments have been grouped by topic 

whenever possible. Comments not involving objections or recommendations 

specifically directed toward the rulemaking or to the procedures followed by the ARB 

in this rulemaking are not included. 

Numerous organizations and individual public citizens submitted comments in 

support of the adoption of the rulemaking, including: the SMAQMD, CalETC, 

BAAQMD, Union of Concerned Scientists, Environmental Defense, Relational 

Cultural Institute, Bayview Hunters Point Community Advocates, NRDC, American 

Lung Association of California , Sierra Club of California , West Oakland 

Environmental Indicators Project, Transportation Solutions Defense and Education 

Fund, Bluewater Network, Coalition for Clean Air, Our Children’s Earth Foundation, 

Regional Asthma Management and Prevention Initiative, California Environmental 

Rights Alliance, Physicians for Social Responsibility – Los Angeles, Residents of 

 

3

 Ms. Acerro’s comments were not specifically directed to the modifications described in the Notice of Public 

Availability of Modified Text issued for a 15-day public comment period beginning on June 28, 2006. 

Specifically, her comments stated that buses and recreational vehicles should not be exempted from the new 

engine idle shutdown requirement. Because these comments are not directed to a modification within the scope 

of the 15-day notice, they are not addressed in this FSOR. 

4

 Mr. Orcholski’s comment expressed general support for the rulemaking but was not specifically directed to the 

modifications described in the Notice of Public Availability of Modified Text issued for a 15-day public 

comment period beginning on June 28, 2006. Because this comment is not directed to a modification within the 

scope of the 15-day notice, it is not addressed in this FSOR. 

5

 TMA’s comments were not specifically directed to the modifications described in the Notice of Public 

Availability of Modified Text issued for a 15-day public comment period beginning on June 28, 2006. 

Specifically, these comments were: (1) The ARB should reconsider TMA’s comments relating to the proposed 

labeling requirements, (2) the leadtime requirements for the new engine idle shutdown and the in-use idling 

portion of the rulemaking are inadequate, (3) the definition of “tamper-resistant and nonprogrammable” in 13 

CCR section 1956.8(a)(6)(A)(1) is unclear, and (4) the new engine shutdown timer portion of the rulemaking 

conflict with federal hours of service regulation. Because these comments are not directed to a modification 

within the scope of the 15-day notice, they are not addressed in this FSOR. 
- 18 - 

Pico Rivera for Environmental Justice, Melissa Guerrero, a South Gate Resident, 

California Asthma Partners, Bay Area Clean Air Task Force, Kirsch Foundation, 

Harold J. Farber, MD, Fresno Metro Ministry, Environmental Law Foundation, 

Grayson Neighborhood Council, Center for Energy Efficiency and Renewable 

Technologies, Schuyler Kennedy, Irwin David, Karla Capers, Stan and Jeanie Haye, 

Arthur Unger, Lola Ungar, Marcie Brown, Ditching Dirty Diesel Collaborative, COVAL 

Partners, Webasto, Theresa Acerro, Gerald Orcholski, and Vinu Arumugham,. The 

comments by CalETC supported the regulation with some recommendations. 

Comments in support of the proposed regulatory actions are not summarized below, 

unless they are relevant to another comment or response. 

The comments summarized below are divided into 12 subsections: (A) General 

Comments, (B) New Engine Shutdown System Requirements, (C) Optional NOx 

Idling Emission Standard and Test Procedures, (D) Auxiliary Power System 

Requirements, (E) Electrical Power Based Alternative Technologies, (F) Compliance 

Cost, (G) Labeling Requirements, (H) Removal of Sleeper Truck Exemption, (I) Air 

Quality Benefits, (J) Leadtime and Stability Requirements, (K) Federal Hours-ofService Requirements, and (L) Commerce Clause Comments 

A. GENERAL COMMENTS

1. Comment: NATSO opposes the proposed elimination of the exemption for 

sleeper berth equipped trucks from the anti-idling requirements of title 13, 

California Code of Regulations (CCR) section 2485. The proposal notes that 

new technologies are entering the market place, but adopting and implementing 

these new technologies will require more time than the time frame specified in 

the rulemaking. Although ARB may wish to accelerate the market adoption of 

idle reduction technologies through a regulatory initiative, it should allow the 

marketplace more time to incorporate the new idle reduction technologies to 

ensure that the economic investments by the trucking and travel plaza 

industries are protected. (NATSO)

Agency Response: ARB disagrees that the time frame for eliminating the 

sleeper berth exemption is too short, because a number of proven and costeffective idle reduction technologies is currently available. For example, APSs 

and truck stop electrification have been available in the market for many years, 

although their penetration into the market has currently been very limited, 

despite the fact that some of these devices can pay for themselves through fuel 

savings in one to two and half years. Also, the regulation will encourage the 

deployment of truck stop electrification at travel plazas, resulting in economic 

benefits for truck stop operators because more truck drivers will rest at 

electrified truck stops, especially those without on-board cab comfort devices. 

Staff does not believe that providing more time for market forces to respond will 

benefit trucking businesses or truck stop operators, since the attitude of the 

trucking industry towards these technologies may remain unchanged in the 
- 19 - 

absence of a regulation. Furthermore, California has severe air quality 

problems that preclude it from delaying the implementation of this rulemaking. 

2. Comment: ARB should acknowledge the significant national efforts already 

underway to develop a national model idling law, and should work with U.S. 

EPA and industry workgroups to develop U.S. EPA’s model idling law, to 

ensure that truck stops within its borders are able to operate on a level playing 

field. (NATSO)

Agency Response: U.S. EPA’s model state idling law was developed to serve 

as a guideline for states or local governments that are considering the adoption 

of idling restrictions in their jurisdiction. U.S. EPA has expressly stated that it is 

not promulgating any type of regulation regarding vehicle idling, and that the 

model law should only be considered informational in nature in the model rule 

(“Model State Idling Law”, EPA420-S-06-001, April 2006, Transportation and 

Regional Programs Division, Office of Transportation and Air Quality). U.S. 

EPA’s Model State Idling “Law” therefore does not require states to adopt an 

idling rule or to ensure that their idling restrictions are consistent with the model 

rule. Staff does not understand how the model law will ensure a level playing 

field for truck stop operators in California, especially since other states are not 

obligated to implement it. However, to the extent that the comment is directed 

to requesting that this rulemaking be consistent with U.S. EPA’s model law, this 

rulemaking is largely consistent with the model law. (See also the Agency 

Response to Comment 3). 

3. Comment: More than 30 different idling regulations currently exist in various 

states, counties, and cities, and these contain different limits and exceptions, 

making it impossible for drivers to know what restrictions are in place and 

whether a particular jurisdiction even has a regulation. ATA has been working 

with U.S. EPA in a national effort to bring consistency to idling regulations. 

Unfortunately, California’s idling regulation is inconsistent with existing idling 

regulations in other states as well as U.S. EPA’s efforts to achieve national 

uniformity through a model law. National efforts are underway to encourage 

the use of alternatives to idling. However, California’s compliance options to 

the idling regulation – 30 gram per hour NOx engine and APSs with PM traps – 

simply do not exist. Thus, California’s technology-forcing strategy is 

inconsistent with national and state efforts to reduce idling. (ATA)

Agency Response: The Agency Response to Comment 2 is incorporated

herein. This rulemaking consists of requirements applicable to both new and 

in-use engines. A comparison of this rulemaking’s in-use idling requirements 

with the requirements in U.S. EPA’s Model State Idling Law shows that both are 

largely consistent with each other. For example, both laws restrict idling of 

diesel trucks to 5 minutes and both contain mostly identical exemptions. The 

requirements regarding diesel-fueled APSs installed on 2006 and older trucks 

are also the same. Although the U.S. EPA model law does not provide any 

specific recommendation for APSs installed on 2007 and newer model year 
- 20 - 

trucks, it also takes no position against this rulemaking’s requirement for a 

Level 3 verified PM control device. In fact, the model law discusses California’s 

requirement for an APS with a Level 3 PM control device as an example of a 

compliance option for APSs applicable for 2007 trucks. Furthermore, as stated 

in the Staff Report, PM filter manufacturers are developing devices for APSs 

and staff expects them to be verified in time such that fully packaged APS 

systems will become available in 2008. Trucking businesses can also utilize 

other currently available, cost-effective technology options (e.g., battery-based 

APSs, thermal energy storage systems, truck stop electrification, etc.) to 

provide power for climate control, engine heating, or electrical power purposes 

that would otherwise be supplied by idling the vehicle’s main engine. 

The U.S. EPA model law for states does not contain recommendations 

regarding idling emission controls for new engines, and therefore can not be 

compared to California’s new engine requirements. This option was included to 

accommodate engine manufacturers’ requests for an option to certify engines 

to a NOx idling emission standard instead of complying with the engine 

shutdown system requirement. See the Agency Response to Comment 11 for 

a discussion on the technical feasibility of the optional NOx idling standard. 

Also, manufacturers would not have requested this alternative compliance 

option if they believed it is infeasible for 2008. Although, as stated in the Staff 

Report, staff did not anticipate that manufacturers would be able to comply with 

this optional compliance option by the 2008 model year, several engine 

manufacturers have already informed staff that they intend to introduce engines 

that comply with the optional NOx idling standard by the 2008 model-year. 

Also, staff expects other states to modify their idling rules to allow trucks that 

comply with the optional NOx idling requirements to operate within their state. 

4. Comment: The in-use idling rule presently exempts military tactical vehicles 

during training. This exemption should be clarified to specify that it also 

encompasses operational modes including training, testing, and deployment. 

(U.S. DOD, CNG) 

 

Agency Response: During the public hearing, staff informed the Board that its 

intent in developing the in-use portion of the rulemaking was consistent with 

this comment. As directed by the Board, staff has accordingly modified the 

 in-use portion of the rulemaking to clarify that that the current exemption of 

military tactical vehicles from the in-use idling requirement also encompasses 

operational modes including training, testing, and deployment. 

 

5. Comment: [Received during the 15-day public comment period]. Military 

vehicles should be exempted from idling limits only during combat. Since 

military vehicles are operated for a vast majority of their lifetimes in non-combat 

environments, there is no reason to exempt them from the idling limit. (Vinu 

Arumugham) 
- 21 - 

Agency Response: No change was made in response to this comment. 

Military personnel must necessarily operate tactical vehicles during training 

exercises as well as during actual wartime or emergency situations. Requiring 

training exercises to be significantly different from actual combat operations 

would impair the military’s combat readiness. Therefore, military vehicles are 

excluded from compliance with the idling requirements during non-combat 

operations such as training, deployment, or testing. 

6. Comment: The ARB should forbid idling and send a $100 check to long-haul 

truck drivers to pay for half of the trucker’s bill for a modest hotel/motel near the 

truck’s route. Paying the trucker’s bills requires a big bureaucracy, but such 

cost is much less than paying for health care for those injured by the PM2.5 

emissions from diesel engines. (Arthur Unger) 

Agency Response: ARB appreciates the comment to the extent that it

supports restricting the extended idling of sleeper berth equipped trucks. 

However, this rulemaking does not include any provision to reimburse truck 

drivers for lodging costs, and ARB believes such reimbursement is 

unnecessary, since truck drivers can instead choose to use any of the 

commercially available cost-effective cab comfort devices to provide for cab 

comfort. Truck operators can quickly recover the cost of such cab comfort 

devices through fuel and maintenance savings. 

7. Comment: We support a rule that does not allow trucks to idle all night, but the 

rule should also apply to buses, which sometimes sit for hours on end idling. 

(Stan and Jeanie Haye) 

Agency Response: As discussed in section IV.A.i. of the Staff Report, the ARB 

is exempting buses from the new engine requirements of this rulemaking 

because they have large volumes and window areas that require operating the 

vehicle’s main engine to power air conditioning systems with a high heating 

and/or cooling capacity. 

B. ENGINE SHUTDOWN SYSTEM REQUIREMENTS

8. Comment: The statement on page 27 of the Staff Report that the key 

requirement of the new engine idle shutdown timer proposal can be 

accomplished with only minor modifications in programming the electronic 

control module (ECM) software to prevent adjustment and tampering is 

incorrect. That assessment and the lack of a feasibility analysis appears to 

trivialize the engineering resources required to address this proposal because 

requiring the engine shutdown system to be non-programmable and tamperproof will potentially require hardware changes to the ECM, software changes 

to the engine calibration, and changes to the electronic service tools used to 

service the heavy-duty engine. This proposal would seriously overburden the 

engineering resources dedicated to meeting the 2007 and 2010 heavy-duty 
- 22 - 

engine emission standards as well as the new challenges of the heavy-duty 

On-Board Diagnostic regulation recently adopted by ARB. (Cummins)

Agency Response: As stated in the Staff Report, the automatic engine 

shutdown system already exists as a programmable feature in most 

electronically controlled heavy-duty diesel engines. Requiring the engine 

shutdown system to be non-programmable and tamper proof may require some 

software changes to the ECM, but the software changes will not require ECM 

hardware changes, since most of the software changes will result in the 

removal of programmable features programmed into the ECM. Staff does not 

believe that the requirements will require changes to the electronic service tools 

used to service heavy-duty engines, as existing electronic service tools will still 

continue to perform all of their designed functions except that the feature 

allowing the ability to reprogram the engine shutdown system for more than 5 

minutes will be removed. Staff therefore believes that the automatic engine 

shutdown requirement will result in negligible costs and minimal additional 

workload. 

9. Comment: [Received during the 15-day public comment period]. EMA 

supports staff’s proposal to provide an idle shutdown override to allow for 

particulate filter regeneration, but the 30 minute allowance proposed is 

inadequate. The time required to safely complete regeneration is somewhat 

indeterminate due to variations in filter soot loading and ambient conditions, but 

will exceed 30 minutes in most cases. In general, up to 35 minutes may 

represent minimum in-service regeneration time under ideal conditions 

(ambient, soot loading, etc.) EMA recognizes that staff’s proposal includes an 

allowance to use regeneration events that are longer than 30 minutes, but this 

will require special advance approval by the Executive Officer. EMA 

appreciates this allowance, but believes it is inappropriate to rely on a special 

approval process to provide flexibility needed for the majority of cases. This 

simply places an extra and unnecessary administrative burden on engine 

manufacturers and on ARB certification staff. Accordingly, EMA recommends 

that staff change the maximum regeneration time from 30 minutes to 60 

minutes. (EMA)

Agency Response: No change was made in response to this comment. The 

ARB surveyed engine manufacturers regarding the length of time their systems 

required to complete stationary regeneration before it specified the engine 

shutdown override allowance for particulate filter regeneration. Engine 

manufacturers’ responses ranged from 15 minutes to 35 minutes, as the length 

of time needed to safely complete most stationary regeneration events. Based 

on this information, staff set the engine shutdown override allowance for 

stationary regeneration to 30 minutes, which means the engine shutdown 

system is enabled at the end of the 30 minute period and shuts off the engine 

after 5 minutes, resulting in a total engine operating period of 35 minutes. 

However, staff recognizes that some engine designs may require additional 

regeneration, and the rulemaking therefore allows manufacturers, subject to 
- 23 - 

advance approval by the Executive Officer, to override the engine shutdown 

system for longer periods of time. Allowing an engine shutdown override time 

longer than 30 minutes to accommodate only rare events may allow 

unnecessary idling and emissions, which reduces the emissions benefit of the 

rulemaking. 

10. Comment: We would like to seek clarification that the automatic shut off device 

would not apply to military tactical vehicles operating in California. 

(U.S. DOD, CNG) 

 Agency Response: During the public hearing, staff informed the Board that its 

intent in developing the new engine portion of the rulemaking was consistent 

with this comment. As directed by the Board, staff has accordingly modified the 

new engine portion of the rulemaking to clarify that military tactical vehicles are 

exempted from the engine shutdown system requirement. 

C. OPTIONAL NOX IDLING EMISSION STANDARD AND TEST PROCEDURES

11. Comment: The alternative NOx idling emission standard (30 g/hr) is not 

technically feasible because NOx aftertreatment devices are not anticipated to 

be feasible until 2010, as conceded in the Staff Report (pages 13 and 28). 

(EMA, Cummins, DDC). This lack of feasibility violates the mandates of 

Health and Safety Code sections 43013, 43018, 43101, and 42 U.S.C. § 

7521(a)(3)(A). [Section 202(a)(2) of the federal Clean Air Act (DDC).] 

 Furthermore, this is not a voluntary or optional standard since it is simply an 

alternative route to compliance “with an emissions control mandate.” (EMA)

Agency Response: As explained in the Staff Report, staff proposed the 

alternative NOx idling emission standard and test procedure to accommodate 

engine manufacturers’ requests for an alternative compliance option to the 

idling shutdown timer requirement. ARB disagrees that the NOx standard is a 

mandatory requirement. “Optional” is defined as “involving an option: not 

compulsory,” and “option” is defined as “the power or right to choose” [2a] or 

“something that may be chosen: as an alternative course of action.” [3a] 

(Webster’s 10th Collegiate Dictionary (1995)). This rulemaking will require 

manufacturers to equip their 2008 and subsequent model-year diesel engines 

with idle shutdown timers unless they choose to certify those engines to the 

subject optional NOx idling emission standard. This also explains why ARB 

disagrees with the commenters’ characterization of the optional NOx idling 

alternative as a “standard”, as this option is only an alternative to the installation 

of a technically feasible automatic idle shutdown device (see Agency Response 

to Comment 8). 

The commenters correctly note that the Staff Report states this option is not 

anticipated to be widely available until 2010 because “NOx aftertreatment 

devices are not anticipated to be employed and other engine idling 

controls/strategies have not been fully demonstrated” (Staff Report, p. 13) and 
- 24 - 

because it is unlikely that engine manufacturers will equip their engines with 

NOx aftertreatment devices that are capable of complying with the NOx 

emission standard before the 2010 model-year (id. at 28). However, ARB 

disagrees that the NOx idling emission standard is not technically feasible. As 

discussed in section IV.A.iii. of the staff report (p. 11), several engine 

manufacturers have indicated that existing NOx aftertreatment devices (such as 

NOx adsorbers) demonstrate the potential to reduce NOx emissions during 

idling. Manufacturers have also suggested that other strategies, such as 

advanced combustion processes, exhaust gas recirculation, operational 

controls such as cylinder deactivation and/or other idling emission control 

strategies may be used to meet the optional NOx idling emission standard. The 

optional NOx idling standard may also be met with engines equipped with NOx 

catalysts. (Section V.B. of the staff report, p. 27). However, this may require a 

supplemental heat source to raise the exhaust temperatures to a level that 

would enable the catalyst to sufficiently reduce NOx emissions, since exhaust 

temperatures during extended idling are generally lower than the catalyst’s 

light-off temperatures. Furthermore, engine manufacturers would not have 

requested this option if they believed it is infeasible. In fact, some engine 

manufacturers have informed staff that they plan to introduce 2008 model-year 

engines that comply with the optional NOx idling emission standard. 

Furthermore, this standard does not violate the cited statues. Health and 

Safety Code sections 43013 and 43018 authorize ARB to adopt standards and 

regulations applicable to new and in-use heavy-duty motor vehicles, and 

section 43101 specifically authorizes ARB to adopt emission standards for new 

motor vehicles and new motor vehicle engines. The NOx idling emission 

standard was developed pursuant to the authority of these and other statutory 

provisions. Section 202(a)(3)(A) of the federal Clean Air Act [42 U.S.C. § 

7521(a)(3)] provides that regulations prescribed by the Administrator of the U.S. 

EPA applicable to emissions of oxides of nitrogen “...from classes or categories 

of heavy-duty vehicles or engines ... shall contain standards which reflect the 

greatest degree of emission reduction achievable through the application of 

technology which the Administrator determines will be available for the model 

year in which standards apply, giving appropriate consideration to cost, energy, 

and safety factors associated with the application of such technology.” Section 

202(a)(2) of the federal CAA provides that any regulation prescribed by the 

Administrator of the U.S. EPA under section 202(a)(1) of the federal CAA shall 

take effect “after such period as the Administrator finds necessary to permit the 

development and application of the requisite technology, giving appropriate 

consideration to the cost of compliance within such period.” These provisions 

are not directly applicable to the NOx idling emission standard because ARB, 

not the U.S. EPA, is promulgating the NOx idling emission standard. To the 

extent that the comments imply the rulemaking is inconsistent with section 

202(a) of the federal CAA, the Board directed staff that to the extent it is 

necessary, to either request a waiver or a confirmation that the regulations are 

within the scope of an existing waiver of federal preemption pursuant to section 

209(b) of the CAA. 
- 25 - 

12. Comment: DDC opposes discontinuing the sleeper truck exception, but fully 

supports the availability of an optional NOx idling standard as an alternative to 

the mandatory 5 minute idle shutdown requirement and the use of APS and/ or 

fuel-fired heaters. (DDC). 

Agency Response: ARB appreciates DDC’s support for the proposed optional 

NOx idling standard. For a response to the sleeper truck exemption issue, see 

the Agency Responses to Comments 58 through 60 and 73 and 74. 

13. Comment: Under the proposal, an APS would be qualified for use if it complies 

with California off-road and/or federal nonroad emission standards and 

procedures for its power category and is equipped with a verified Level 3 (85% 

reduction) strategy for particulate matter (PM) control or has its exhaust routed 

directly to the vehicle's exhaust system upstream of the particulate filter. 

California and federal emission off-road / nonroad emission standards for 

engines in the below 19 kW category are 7.5 g/kWh for NOx+NMHC and 0.80 

g/kWh for PM. When equipped with an 85% effective Level 3 PM control, 

assuming such a control were available, a California compliant off-road engine 

could emit 7.5 g/kWh of NOx+NMHC and 0.12 g/kWh of PM. Using ARB's 

assumption of 5 kW of peak power demand, this APS would emit approximately 

37.5 g/hr of NOx+NMHC2 and 0.60 g/hr of PM when operating in-use to provide 

cab climate control and electrical needs during driver rest periods. 

2008 and later heavy-duty engines certified for on-highway use will be 

equipped with PM filters and will have PM emissions that are near zero and will 

certainly have idle PM emissions that are well below 0.60 g/hr. Similarly, the 

NMHC emissions of these engines will be essentially zero. Given the 

substantial PM and NMHC advantages that the main engines are likely to have 

relative to qualified APSs, DDC believes that the objective of environmental 

equivalence between main engine idling and APS usage suggests that the 

optional NOx idle limit be set no lower than 40 g/hr rather than 30 g/hr as ARB 

has proposed.3 4 (DDC) 

 

Agency Response: First, staff would like to clarify that the required APS Level 

3 PM control or 85 percent PM reduction is relative to the Tier 4 off-road PM 

standard which is 0.4 gram per horsepower-hour and not 0.8 grams per 

horsepower-hour as DDC suggests. Second, the APS does not operate at the 

peak power load of 5 kilowatt at all times, and therefore multiplying the APS 

standards by 5 kilowatt to determine the gram per hour emission rates grossly 

overestimates the APS emission rates. A more appropriate load would be to 

use the annual average power demand of 2.7 kilowatt, as specified in the Staff 

Report (page 45). Finally, staff does not agree that idling truck engines will 

have substantial PM and NMHC advantages than qualified APSs. This is 

because staff estimate that a PM trap equipped on-highway engine to emit 0.16 

grams per hour PM (Staff Report page 44) and this is comparable to an APS 

emission rate of 0.16 grams per hour (estimated assuming an APS with a Level 
- 26 - 

3 PM control device emitting at the standard of 0.4 grams per horsepower-hour 

and the average load of 2.7 kilowatt). Staff also believes that the truck engine 

does not have a significant advantage relative to a qualified APS in terms of 

NMHC emissions. Staff estimates a 2007 and later engine to emit 8.3 grams 

per hour of HC while a qualified APS emits approximately 1.0 grams per hour 

(estimated assuming a 7.5 grams per horsepower-hour NOx+NMHC, a 2.7 

kilowatt load, and the NMHC to be 5 percent of the total NOx+NMHC). 

13a. Comment: (Footnote 2 of comment 13) DDC is aware that ARB has estimated 

the NMHC+NOX emission rate at 15.1 g/hr (ISOR page 46). For several 

reasons, we believe this estimated value is inappropriate as a basis for 

establishing the optional NOx idling standard. First, this estimate is based on a 

survey of certified emission levels for off-road engines in the 5-19 kW rated 

power range. ARB indicates that the average NOx+NMHC emissions from this 

survey is 5.6 g/kW-h. The certification standard is 7.5 g/kWh for engines in this 

power category and under 2485 (c)(3)(A) use of an APS emitting at the level of 

the off-road standard would be permitted. As such, it is the emission standard 

and not the average emissions of certified engines that should be the basis of 

the idle emission standard. (DDC) 

Agency Response: DDC’s statement that ARB used a NOx+NMHC emission

rate of 15.1 gram per hour to determine the NOx idling emission standard is 

incorrect. ARB intends to set the optional NOx idle standard at a level 

equivalent to real-world, in-use APS NOx emissions, as opposed to the APS 

NOx certification standard. In the absence of actual in-use emissions test data 

for APSs, staff analyzed off-road engine certification data for engines in the less 

than 19 kilowatt power category to estimate the in-use emissions from these 

engines. Staff’s analysis yielded an average in-use APS emission rate of 5.6 

grams per kilowatt-hour for NOx+NMHC emissions. Assuming a 5 kilowatt of 

peak power demand, the APS NOx+NMHC emissions would be 28 grams per 

hour. Assuming the NOx portion to be 95 percent of the total NOx+NMHC 

emissions, the APS NOx emissions would be 26 grams per kilowatt hour. 

However, considering the relative size of the truck engine, staff rounded this 

number up and set the NOx idling standard at 30 grams per hour. The 

commenter’s use of the APS engine standard to set an equivalent NOx idle 

standard for the truck engine does not reflect the real-world emissions from 

APSs. Furthermore, only the NOx component of the emissions should be 

considered in setting the NOx idling standard, rather than the total emissions of 

NOx+NMHC, which the commenter used in calculating its proposed NOx idling 

standard of 37.5 grams per hour. 

13b. Comment: (Footnote 2 of comment 13) Secondly, It is recognized that the 

certification emission levels used in this analysis are values that are weighted 

over the certification test cycle. The brake specific emission levels at particular 

speed and load operating modes can be considerably different than the 

weighted cycle values. In fact, for load conditions that are below 40% of the 

rated engine power, the brake specific emissions increase rapidly and may be 
- 27 - 

50 or 100% greater than the weighted cycle emissions. ARB estimates that inuse the APS power demand would be about 2.7 kW, well below the 5-19 kW 

power ratings of the engines in the survey. In all probability the brake specific 

NOx emission of these APS engines under the conditions they are expected to 

operate in the field will be considerably higher than the 5.6 g/kWh value that 

ARB used in their analysis. Finally, the 15.1 g/hr NOx emission rate was 

generated by multiplying the presumed brake specific NOx emission rate of 5.6 

g/kWh by the average applied loading of 2.7 kW. As ARB has acknowledged 

and to be consistent with the way the idle NOx emissions are being quantified 

for purposes of assessing compliance, the brake specific emissions should be 

multiplied by the maximum loading of 5 kW and not the average loading of 2.7 

kW. While DDC's estimated APS NOx emission rate of 37.5 g/kWh lacks rigor 

and shares some of the same deficiencies as the ARB analysis, we believe it is 

a more accurate, though still somewhat conservative assessment of expected 

in-use emissions of APS engines. (DDC) 

Agency Response: Staff agrees that brake specific emission levels at 

particular speed and load operating modes can be different than the weighted 

cycle values. However, staff is not sure whether loads below 40% of the rated 

engine power produce emissions levels that are 50 or 100 percent greater than 

weighted cycle emissions, since DDC did not provide any data or reference to 

substantiate this claim. Nevertheless, in determining the brake-specific 

emission levels during engine certification testing, emissions obtained at load 

operating modes of 50 percent of maximum test torque and lower are weighted 

more than emissions for load operating modes above 50 percent6. DDC may 

also be correct that a 2.7 kilowatt power demand may produce emissions that 

are higher than the certification data average emission rate estimate of 5.6 

grams per kilowatt hour. However, contrary to DDC’s suggestions, staff did not 

use the 2.7 kilowatt power or the 15.1 grams per hour emission rate to establish 

the NOx idling emission standard. As explained in the Staff Report (page 45), 

the APS average power demand for winter conditions is 2.3 kilowatt and for 

summer conditions 3.1 kilowatt. Staff determined an annual average power 

demand of 2.7 kilowatt for purposes of estimating emission reductions and not 

for establishing the optional NOx idling standard. Consistent with what DDC 

requested, staff used the maximum loading of 5 kilowatt power to establish the 

optional NOx idling standard. Contrary to what DDC believes, staff believes 

this is the appropriate analysis to establish the optional NOx idling standard. 

13c. Comment: (Footnote 3 of comment 13) DDC believes that if, as ARB suggests, 

the intent is to set an optional idle NOx standard that is equivalent to APS NOx 

emissions, the surest and fairest way to achieve this objective is to require both 

APSs and main engines to meet a common grams per hour NOx standard 

when tested under conditions that simulate the expected in-use operation when 

 

6

 For example, the loading (percent of the maximum test load) and the weighting factors (WF) for the 5-modes 

of the D2 test procedure are: Mode 1 - 100% of test load and the WF is 0.05; Mode 2 - 75% of test load and the 

WF is 0.25; Mode 3 - 50% of test load and the WF is 0.30; Mode 4 - 25% of test load and the WF is 0.30; and 

Mode 5 - 10% of the test load and WF is 0.10. 
- 28 - 

providing power for cab climate control and electrical loads. This standard 

should be set after a thorough review of the technical capabilities of the two 

types of engines. (DDC) 

Agency Response: In determining the optional NOx idling standard, staff used 

the best available data on APS power requirements for providing cab comfort. 

This data included average and peak power demands for both winter and 

summer conditions. Staff believes that these data together with certification 

test data are good enough to establish the equivalent optional NOx idling 

standard. 

13d. Comment: (Footnote 4 of comment 13) As proposed I956.8(a)(6)(C) indicates 

that in order to become certified to the optional NOx idling standard, the NOx 

standard must be met without increasing the emissions of CO, PM, or ROG. It 

is not clear how the "baseline" levels of CO, PM and ROG are to be determined 

when assessing compliance with this provision. More importantly though, 

because of the well known emission trade-offs that exist for diesel engines, it 

will be practically impossible to affect a reduction in NOx emissions without 

negatively impacting the emissions of CO, PM or ROG to some degree. DDC 

believes that this troublesome provision relating to CO, PM and ROG emissions 

needs to be removed if the NOx idling standard is to be a credible option. 

(DDC) 

Agency Response: Staff agrees that controlling emissions of one pollutant 

might affect emissions of other pollutants. However, the purpose of this 

requirement is to prevent manufacturers from using strategies that may 

significantly increase emissions of PM, CO, and HC, while controlling NOx 

emissions in order to meet the standard. One way of ensuring that this does 

not happen is to compare emissions test results of PM, CO, and HC from the 

NOx idling test procedure with corresponding emissions from the idle mode of 

the supplemental emission test or idle portions of the transient test procedure. 

14. Comment: [Received during the 15-day public comment period]. Section 

1956.8(a)(6)(C) specifies that a manufacturer certifying to the optional NOx 

idling standard must not also increase emissions of CO, PM and reactive 

organic gases (ROG). However, the regulated species for heavy-duty diesel 

engines is non-methane hydrocarbons (NMHC). (EMA) 

Agency Response: Staff agrees. ARB’s heavy-duty diesel engine exhaust 

emission standards for hydrocarbon emissions only specify non-methane 

hydrocarbon (NMHC) levels, and this is widely known by the regulated 

community. The staff has therefore accordingly modified the regulation and 

test procedures by substituting NMHC for ROG. 

15. Comment: [Received during the 15-day public comment period]. The regulation 

and test procedure requires manufacturers certifying engines to the optional 

NOx idling emission standard to compare emissions generated during the 
- 29 - 

supplemental NOx idling test procedure to emissions generated during the idle 

mode of the supplemental steady-state test “and/or” during the idle portions of 

the transient test cycle. The usage of the “and/or” term is confusing and 

ambiguous since it can be interpreted either as a conjunctive or a disjunctive 

term, or both. (EMA)

Agency Response: Staff’s intent in drafting this provision was to allow a 

manufacturer to choose which test cycle it wanted to use for comparison to the 

supplemental NOx idling test procedure- either the idle mode of the 

supplemental steady-state test, the idle portion of the transient test cycle, or 

another test procedure, subject to advance Executive Officer approval. Staff’s 

understanding is that the term “and/or” is interpreted as a disjunctive term, but 

is amending the regulation and test procedure by substituting “or” for “and/or” to 

eliminate any possibility of confusion. 

16. Comment: [Received during the 15-day public comment period]. The steady 

state and transient tests are designed to provide emission results for gaseous 

emissions and PM that are weighted over the prescribed test cycle. These 

tests do not yield emission results that are specific to the idle portions of these 

tests and therefore the bases for comparison that ARB requires to be used 

simply do not exist. (EMA)

Agency Response: The Agency Response to Comment 15 is incorporated 

herein. ARB has identified the steady state and the transient certification tests 

as two tests that manufacturers may elect to utilize to compare emissions 

generated during these tests against emissions generated during the 

supplemental NOx idling test, in order to determine that these emissions are 

not adversely affected. If a manufacturer does not want to measure emissions 

using the idle portions of either of the specified two certification test procedures, 

it can use other procedures, subject to advance Executive Officer approval. 

17. Comment: [Received during the 15-day public comment period]. When an 

engine is operating on the idle portions of the steady-state and transient 

certification tests, it is operating at its normal curb idle speed with no external 

load applied. The supplemental NOx idling test procedure requires the engine 

to be operated at two specified modes involving the application of external 

loads, and the second mode requires the engine to be operated at elevated 

speed. The higher loads and speed of the supplemental NOx idling modes will 

result in increased grams/hour emissions of CO, HC, and PM and will make it 

virtually impossible to comply with the “no increase” requirement. 

 Also, there is no meaningful baseline that can be used to compare with the CO, 

NMHC and PM emissions from the two modes of the supplemental NOx idling 

test procedure. As a result ARB must either develop specific grams per hour 

standards for these constituents over the NOx idling test or remove entirely 

requirements for these emission constituents. EMA recommends that ARB 

follow the latter course. (EMA)
- 30 - 

Agency Response: The Agency Response to Comment 16 is incorporated

herein. The “no increase” requirement serves as a stop-gap measure to 

prevent manufacturers from adversely affecting emissions of CO, NMHC, and 

PM in order to comply with the optional NOx idling standard. Staff agrees that 

the higher load and engine speeds of the supplemental NOx idling modes may 

result in higher gram per hour emissions of NMHC, CO, and PM than those 

from tests conducted at curb idle and at no load conditions. However, to check 

if emissions have been adversely affected or to make emissions from the 

various tests comparable, manufacturers may compare brake-specific 

emissions (i.e., normalize the gram per hour high load-high speed emissions by 

the horsepower load and compare them with gram per horsepower-hour 

emissions of the idle mode of the supplemental steady state test or the 

transient test). Manufacturers can also use other acceptable methods to 

demonstrate that CO, NMHC, and PM emissions are not adversely affected in 

complying with the optional NOx standard. 

18. Comment: The proposed supplemental NOX idling test procedure is overly 

burdensome and does not account for differences between sleeper and nonsleeper trucks. An engine manufacturer must determine needed engine loads 

for all the numerous truck and engine configurations. A manufacturer can 

estimate a worst case scenario of engine load, but this would require emission 

reductions, and therefore an emission level lower than that required to meet the 

optional standard. 

 Also, the optional standard requires averaging of Mode 1, a “loaded” curb idle, 

and Mode 2, ramped sleeper mode. However, as specifically noted by ARB, 

Mode 2 is primarily used for sleeper berth trucks and not the non-sleeper trucks 

(e.g. medium duty delivery trucks). Therefore, requiring non-sleeper trucks to 

be tested and meet sleeper truck requirements is arbitrary and overly 

burdensome. (International)

Agency Response: When a manufacturer certifies heavy-duty engines, it 

does not know what application the engines will be placed in, or whether they 

will be installed in a sleeper berth equipped truck or not. Some new trucks are 

being engineered to allow easy conversion into a variety of body styles. For 

example, day cabs can easily be converted into sleeper trucks and vice versa. 

For these reasons, all engines are required to meet the same emission 

standards irrespective of the truck’s initial body design or the application that 

they are going to be installed in. 

 Staff also wishes to clarify that the regulation does not require averaging of 

Mode 1 and Mode 2 emissions. As clarified during the 15-day notice, 

compliance with the optional NOx idling standard, only requires that the 

average NOx idling emissions of each mode shall not exceed the optional NOx 

standard of 30 grams per hour. 
- 31 - 

19. Comment: ARB staff has not provided reasonable justification for the 

proposed idle emission test procedure. The staff’s comment that truck 

operators elevate idle speed to provide more power for cab comfort and 

accessory devices may be true, but ARB did not provide statistical 

data/justification to determine if the specified speeds and loads are indicative of 

in-use extended idle operation. A manufacturer should be allowed to determine 

the appropriate idle test procedure, which would be indicative of expected 

speeds and loads for the different heavy-duty diesel engine platforms and 

applications, and which would result in a more accurate test procedure for 

evaluating idle emissions. (Cummins)

20. Comment: The specified test procedure is unnecessarily complex and may not 

accurately quantify NOx idle emissions during actual extended idle operations. 

First, the two modes specified in the supplemental NOx idling test procedure 

may not represent the conditions that a particular engine will operate in during 

periods of extended idle in actual use. Manufacturers should be permitted, with 

Executive Officer approval, to specify an alternative mode or set of speed/load 

modes with appropriate weighting factors which will represent how the engine is 

expected to operate in-use during extended rest periods. This flexibility will 

permit a more accurate appraisal of the actual in-use emissions. (DDC)

Agency Response to Comments 19 and 20: The Agency Response to 

Comment 16 is incorporated herein. Based on staff’s knowledge and 

experience, most truck operators do elevate idle speeds during overlay periods 

to provide more power to operate cab comfort devices and to reduce vibration 

of the cab. In determining the test speed for mode 2, staff referred to two 

survey studies that described operator practices of elevating engine speeds 

during extended rest periods7 and to engine manufacturers’ practice of setting 

engine electronics in the automatic stop-start system to operate the engine at 

higher engine speeds during extended idling. In general, the results from the 

two survey studies indicated that most truck operators idle their engines at 850 

rpm or higher. In particular, the study by Irck et al, notes that nearly 50 percent 

of the drivers operated their engines at 1000 rpm or higher, with 40 percent 

reporting between 1000 and 1100 rpm. These studies therefore suggest that 

idling engines within this speed range is a common practice by a substantial 

proportion of drivers. Engine manufacturers that equip their engines with 

automatic engine stop-start systems, some of which include the commenters 

referenced above, also program the engine’s electronics to raise the engine 

speed to 1100 rpm when the system is in the engine run or start mode. Thus, 

staff’s decision to set the test speed for mode 2 be 1100 rpm is based on best 

available published data and on manufacturers’ own practice of programming 

engine electronics to elevate engine speeds to 1100 rpm during extended idling 

 

7

 (1) Brodrick, Christie-Joy, N. P. Lutsey, Q. A. Keen, D. I. Rubins, J. P. Wallace and H. A. Dwyer, and S. W. 

Gouse, III. Truck Idling Trends: Results of a Pilot Survey in Northern California, SAE 2001-01-2828 

 (2) Irck, David and B. Wilson. NOx Emissions and Fuel Consumption of HDDVs during Extended Idle. 

Presented to the Coordinating Research Council’s 12th Annual On-Road Vehicle Emissions Workshop, San 

Diego, CA, April 15-17, 2002. 
- 32 - 

operation. Furthermore, the test procedure does provide manufacturers with 

the flexibility to use alternative test procedures with prior approval from the 

Executive Officer. 

21. Comment: The specified test cycle is unnecessarily complicated by requiring 

the specified torque to be held within +/- 2 percent. In the idle mode test for the 

supplemental emission test certification testing, the idle torque requirement 

cannot exceed 5 percent of the peak torque at peak torque speed. That 

specification is more appropriate than the proposed requirement by the ARB. 

First, it is assumed that the ARB staff is specifying +/- 2 percent of the engine 

idle load, and secondly, 2 percent of a light load or near-zero load as will be the 

case for curb-idle speed mode, is not only impractical but also not achievable 

as a test specification. (Cummins)

22. Comment: The test cycle requires torque to be held within 2 percent 

throughout each test mode. Holding torque within 2 percent of the torque at the 

specified test modes (40 N-m/ 30ft-lb at mode 2 and approximately zero at 

mode 1) is beyond the capabilities of laboratory test systems. This 

specification should be revised to provide an absolute tolerance of 20 N-m/ 15 

ft-lb. (DDC) 

23. Comment: [Received during the 15-day public comment period]. The 

requirement that the specified torque for the NOx idle test modes must be held 

within +/- 2% of the target load value is unreasonable and infeasible at the 

loads represented by these test modes. The torque tolerance specification 

should be modified to allow for a tolerance of +/- 2% of the maximum torque of 

the engine. (EMA) 

Agency Response to Comments 21 through 23: Although it is not clearly 

stated in the test procedure, staff’s intent is that the torque must be held within 

±2 percent of the maximum torque at that test speed. This tolerance is 

consistent with other similar test requirements such as the one specified in U.S. 

EPA’s heavy-duty diesel engine test procedures (CFR, Part 86, Subpart N, 

section 86.1360-2007). Staff has accordingly modified Section 86.1360-

2007.B.4.2.2 of the test procedures to clarify this requirement. 

24. Comment: The engine coolant, oil, and fuel pumps are integral to operation of 

the engine and need not be separately accounted for in setting loading 

requirements at each of the test modes. The air compressor does not typically 

operate during extended idling and therefore should not be accounted for in the 

test modes. Similarly, the alternator need not be accounted for other than the 

electrical load specified in mode 2. Since the NOx emissions limit is 

established by reference to emissions of an APS certified using off-road 

certification test procedures, and since these procedures do not account for 

cooling fan load, cooling fan load should also not be accounted for in this 

testing. In short, the maximum air conditioning compressor load and the 
- 33 - 

simulated 2 kilowatt electrical load should be the only external loads applied 

during this testing. (DDC)

Agency Response: No change was made in response to this comment. The 

test procedure requires the engine manufacturer to determine the appropriate 

test load for the two test speeds, i.e., curb idle speed and 1100 rpm, and also 

identifies several engine accessories that may operate during engine idling and 

therefore need to be accounted for in determining the test load. If an accessory 

is integral to operation of the main engine, the test procedure does not require it 

to be separately accounted for in determining the test load. However, the total 

load or power requirement reported to the ARB during engine certification must 

include the loads contributed by engine accessories that are also integral to the 

operation of the engine. 

Staff does not agree with the statement that the air compressor does not 

operate during engine idling. The air compressor is connected to the engine 

through gears or belts. Therefore, whether it is pumping air or not, the air 

compressor will be driven by the engine at all times, exerting load on the 

engine. If the air pressure in the reservoir falls below a certain set pressure 

(approximately 100 psi), then the air compressor is activated and starts 

pumping pressurized air to the reservoir, exerting a much higher load on the 

engine. Similarly, the alternator is also connected to the engine through a belt 

drive. Whether the alternator is charging the battery or not, it also will exert 

load on the engine as long as the engine is operating. Therefore, the load 

required to drive the alternator also needs to be accounted for in determining 

the test load unless it is accounted for in the engine’s certification testing. 

Furthermore, the test procedure is designed to measure emissions by 

simulating engine loads and speeds that typically occur during extended idling 

of a truck, not to mimic the off-road certification test procedure. Extended idle 

tests of heavy-duty trucks have shown that the cooling fan cycles on and off 

during idling, increasing NOx emissions substantially when the cooling fan is 

operating. Therefore, staff does not agree with the suggestion that the cooling 

fan load should not be accounted for as part of the test load. 

25. Comment: First, specifying a percentage temperature tolerance without also 

specifying the temperature scale is ambiguous. The testing requirements 

specify that the engine must run for 10 minutes and reach temperature stability 

(defined as the point at which the engine coolant temperature is within 2 

percent of its mean value for at least 2 minutes) before emission sampling can 

begin. The form of this specification is confusing and may be very difficult to 

comply with. If the “mean value” referenced is intended to be the mean value 

of the coolant temperature over the prior 2 minutes of running, then the mean 

value will be continuously changing value. By the time the test operator can 

determine if the coolant temperature has been within tolerance over the 2 

minute period, a new two minute period, mean value and range of coolant 

temperatures will be underway. Finally, requiring both a 10 minute running time 
- 34 - 

and a coolant temperature stability requirement is unnecessary. The conditions 

for entry into emissions sampling at a test mode should be revised to either 10 

minutes of operation at the specified engine speed and load or a showing that 

the engine coolant temperature did not vary by more than 5 degrees C over the 

sampling period. Test operators choosing the second option could start 

emissions sampling upon reaching the specified engine speed and load 

conditions and terminate sampling after an 1800 second sampling period in 

which the temperature stability conditions are met. (DDC) 

Agency Response: The method for determining engine coolant temperature 

stability specified in the proposed test procedure was adopted from the engine 

testing procedures in Title 40, Code of Federal Regulations, section 1065.530. 

Staff proposed this method of determining temperature stability to ensure it was 

consistent with industry-wide, accepted standardized test procedures that 

manufacturers must utilize when performing engine tests for emission 

certification purposes. It is also clear from the proposed language that the term 

“mean value” is intended to refer to the mean value of the coolant temperature 

measured during the prior 2 minutes of engine operation. If the coolant 

temperature is stabilized and remains within tolerance over the prior 2 minutes, 

it is highly likely that the coolant temperature will also remain within tolerance in 

any consecutive 2 minute periods; otherwise the coolant temperature is not 

stabilized. Furthermore, the requirement to operate the engine for at least 10 

minutes before taking emissions measurements is needed to avoid measuring 

emissions immediately after a preconditioning run when the NOx aftertreatment 

device is still hot and will help ensure that emissions are measured under 

conditions that are approximately similar to those experienced during an 

extended idle operation mode. Also, the specified percentage temperature 

tolerance applies to the CFR specified temperature scale used during 

certification testing. For example, section 1065.20(a)(3) of the CFR specifies 

degree Celsius (°C) as the unit of measure for temperatures. A manufacturer 

may also use degree Fahrenheit (°F) as the unit of measure which would result 

in a temperature tolerance that is slightly greater than that calculated if the unit 

of measure was in degree Celsius. 

26. Comment: Paragraph 4.2.3 of 86.1360-2007(B) requires that the average 

modal emissions in grams per hour be calculated for each regulated pollutant. 

Requiring the measurement of each regulated pollutant increases the testing 

burden and serves no useful purpose, given that only NOx limits are being 

established. This paragraph should be modified to make it clear that only NOx 

measurements are required. (DDC) 

Agency Response: The regulation requires that manufacturers electing to 

certify to the optional NOx idling standard must demonstrate their engines will 

not also adversely affect emissions of CO, NMHC, and PM. The emissions of 

each pollutant are therefore required to demonstrate that CO, HC, and PM 

emissions are not adversely affected. 
- 35 - 

D. AUXILIARY POWER SYSTEM REQUIREMENTS 

27. Comment: The proposed requirement [Title 13, CCR section 

2485(c)(3)(A)(1)(i)] that diesel-fueled APSs must be equipped with a verified 

Level 3 in-use strategy for particulate matter control is an emission standard 

that is not technically feasible, in violation of state and federal law. (California 

Health and Safety Code sections 43013, 43018, and 43101, and the federal 

Clean Air Act sections 213(a) and 209(e)(2)). (EMA)

Agency Response: This requirement is not a standard that regulates new 

motor vehicles or new motor vehicle engines, but rather constitutes a control on 

existing, in-use nonroad or off-road engines. APSs are classified as nonroad 

engines because they do not supply power to propel on-road vehicles; instead, 

they are mounted on trucks and produce the power for heating or air 

conditioning that would otherwise be supplied by the vehicle’s primary engine. 

To the extent it is necessary, ARB will be filing a request for authorization for 

this requirement with the Administrator of U.S. EPA pursuant to Clean Air Act 

section 209(e)(2). 

ARB disagrees that this requirement is not technically feasible. During the time 

that the Tier 4 off-road regulation was being developed, no aftertreatment 

technology was commercially available for diesel engines in this category. 

Thus in the staff report, staff could not specifically elaborate on the feasibility of 

using aftertreatment on these smaller engines. However, there is no inherent 

PM emission characteristic that would prevent the use of a PM filter system, 

similar to what will be used on larger diesel engines. The only characteristic of 

a small diesel engine that is different than a larger engine is the exhaust 

temperature, which is typically lower in a small engine, requiring the use of an 

active regeneration strategy of the PM filter for the system to work. It is well 

understood that the aftertreatment being developed for 2007 on-road heavyduty diesel engines will also employ this type of strategy to prevent the 

possibility of PM filter failure under certain low exhaust temperature operation. 

Thus, the development of on-road diesel PM filters that will be deployed on all 

trucks beginning in 2007 is similar to the technology needed for small off-road 

diesel engines, except the size and active regeneration strategies may need 

some modifications to fit the application. 

Moreover, the APS requirement is consistent with and does not violate the cited 

statues. Health and Safety Code sections 43013 and 43018 authorize ARB to 

adopt standards and regulations applicable to new and in-use off-road or 

nonvehicle engine categories, and the APS requirements at issue were 

developed in part under the authority of these two provisions. Section 43101 

authorizes ARB to adopt emission standards for new motor vehicles, and is 

therefore not applicable to this in-use control of existing nonroad engines. 

Section 213(a) of the federal Clean Air Act [42 U.S.C. § 7547(a)] is similarly 

inapplicable to this requirement because it directs the Administrator of the U.S. 
- 36 - 

EPA to perform specific actions pertaining to promulgating regulations 

applicable to new nonroad engines and vehicles. As previously stated, ARB 

may request an authorization for the APS requirement with the U.S. EPA. 

Section 209(e)(2) [42 U.S.C. § 7543(e)(2)] specifies the criteria the 

Administrator of U.S. EPA will utilize in determining whether to grant ARB an 

authorization; namely, if there is any basis for finding ARB acted arbitrarily and 

capriciously in determining the APS requirements are at least as stringent as 

applicable federal standards, whether California does not need its own 

standards to meet compelling and extraordinary conditions, and whether 

California’s standards are consistent with section 209 of the CAA. The U.S. 

EPA will therefore be making each of these findings in responding to ARB’s 

request for authorization under CAA section 209(e). 

28. Comment: To guard against any unintended increase in aggregate emissions 

from the expected increase in the installation and use of APSs, ARB is 

proposing a new series of emission standards for the small diesel-fueled offroad engines that power APSs. The off-road engines used in APSs are already 

subject to a set of extremely stringent Tier 4 emission standards both as 

adopted by U.S. EPA and then the ARB. ARB’s proposal to establish new and 

different standards for APSs is a breach of faith and contrary to the agreedupon commitment by ARB to EMA to fully align and harmonize its off-road 

standards with those adopted by U.S. EPA. (EMA)

29. Comment: The proposed regulation is flawed in that U.S. EPA and ARB have 

already laid out the Tier 4 path as the best feasible technology for the 

immediate future. If adopted as proposed, this regulation reneges on that 

agreement to harmonize the development and use of Tier 4 engines. (Pony 

Pack) 

Agency Response to Comments 28 and 29: The ARB has adopted 

regulations that harmonize emission standards on a national basis for most 

on-road and off-road diesel engines. This regulation does not change the Tier 

4 off-road emissions standards nor does it require engine manufacturers to 

install particulate filters on these engines. Therefore, the statements that this 

rulemaking breaches ARB’s agreements in adopting the Tier 4 off-road 

emission standards are simply not accurate. Catherine Witherspoon, ARB’s 

Executive Officer, explained at the public hearing that before the Board adopted 

the Tier 4 standards, it adopted a Diesel Risk Reduction Program to reduce 

diesel particulates from in-use vehicles, and during the same time the Board 

was considering the Tier 4 off-road standards, it adopted the current idling 

regulation (in Title 13 CCR section 2485) and split it in two parts. The Board 

adopted a five-minute limit for general idling and directed staff to return this 

year with a proposal regulating sleeper cab idling emissions. Therefore, the 

idea that the Tier 4 rulemaking somehow prevented ARB from regulating all 

those other activities is simply just accurate. While it was adopting the Tier 4 

off-road standards the Board had multiple regulatory efforts underway. 
- 37 - 

 This rulemaking specifies that if an operator of a 2007 or later model year truck 

wants to operate a diesel-fueled APS in California, he or she must then control 

the PM emissions from the APS either by using a Level 3 verified PM control 

strategy or by routing the APS’s exhaust into the exhaust system of the main 

engine. This requirement is designed to prevent excess emissions when a 

diesel APS is used instead of idling the truck engine, and specifically allows 

diesel APSs to be used as a compliance option, instead of flatly prohibiting their 

use. Particulate filter manufacturers are currently developing filters for APSs 

and staff expects a fully compliant APS to become available in 2008. Finally, 

see the Agency Response to Comment 27 for a discussion regarding the 

feasibility of a PM trap for APS applications. 

30. Comment: A Level 3 verified particulate filter for a diesel APS using a Tier 4 

engine is not yet commercially available. We currently know of no such device 

for this application. A better course of action would be to require the use of an 

automatic shut-down/restart cycling system of the small engine when used in 

an APS. (Pony Pack).

Agency Response: The Agency Response to Comment 27 is incorporated 

herein. The regulation contains a provision allowing a manufacturer to use an 

alternative compliance strategy for APSs, subject to advance approval from the 

Executive Officer (see Section 2485(c)(3)(A)(2)). For example, Pony Pack may 

develop a compliance strategy that uses an automatic shut-down/restart cycling 

system in combination with other strategies, to demonstrate compliance with 

the diesel APS requirements. 

31. Comment: The ARB should delay the aftertreatment requirements of small 

engines to a future time, such as 2011, when the Tier 4 rule requires the next 

category of engines (above 25 hp) meet exceedingly low PM levels. (Pony 

Pack) 

32. Comment: It is not clear whether diesel APS manufacturers will be able to 

introduce products that meet the required Level 3 PM control, and it may 

therefore be prudent to revisit the implementation date issue at a later date. 

(CCEEB).

33. Comment: APS manufacturers might not be able to meet the proposed 

requirements (develop a Level 3 verified PM control for APSs). (ATA, TMA) 

Agency Response to Comments 31 through 33: The Agency Response to 

Comment 27 is incorporated herein. As stated above, staff believes that 

particulate filters for APSs will become available before the 2008 

implementation date, and therefore disagrees that the implementation date of 

the APS requirements should be extended. However, in the event that no 

Level 3 technology is available in 2008, truck operators will have other available 

cab comfort technologies to choose from that already meet the requirements of 
- 38 - 

this regulation, such as battery electric APS and thermal energy storage 

systems. 

34. Comment: Even if a Level 3 PM trap for the small engines powering APSs 

becomes available, there is not enough time to integrate the device into this 

application and then conduct enough field testing and design refinement to 

ensure the APS will perform satisfactorily and reliably. Also, the cost for such 

systems may increase beyond the $5,000 to $10,000 range, making them that 

much less attractive to truck buyers and operators. (TMA)

Agency Response: It should be noted that the rulemaking requires that a 

diesel powered APS be equipped with a verified Level 3 in-use strategy for 

particulate matter. The PM trap must therefore first be verified under ARB’s 

verification procedures. ARB’s verification procedures involve a thorough 

evaluation of the emission reduction capability of a trap and of its durability. 

The verification process ensures that the emission reductions achieved by the 

trap are both real and durable, and that production units in the field are 

achieving emission reductions that are consistent with the verification. It also 

requires the trap manufacturer to warrant its product that the verified PM trap is 

free from defects in design, materials, workmanship, and operation of the trap 

achieves the emission reduction levels it was verified to. Thus, although the 

commenter is concerned regarding the time needed to conduct field testing and 

design refinement, most, if not all, of these efforts will have already been 

conducted by the trap manufacturer. 

As stated in the Agency Response to Comments 31through 33, this rulemaking 

does not mandate usage of a diesel APS. The cost of diesel APSs equipped 

with Level 3 verified PM devices reflect staff’s best estimates, and the bases for 

staff’s cost estimates are fully set forth in sections V and VII of the Staff Report. 

35. Comment: Allowing the exhaust from diesel-fueled auxiliary power supplies 

(APSs) to be routed into a truck’s diesel particulate matter aftertreatment device 

might jeopardize “engine warranties, which can be nullified if the engine is 

modified. It remains to be seen whether engine manufacturers would consider 

this to be a form of tampering.” (CTA)

36. Comment: Routing the exhaust from a diesel APS into a truck’s diesel 

particulate matter aftertreatment device requires the heavy-duty diesel engine 

manufacturer’s guidance and approval. (Cummins)

Agency Response to Comments 35 and 36: Existing statutory and 

regulatory provisions regarding warranty requirements for medium and heavyduty vehicles and engines, and on-road aftermarket parts, ensure that routing a 

diesel-fueled APS’s exhaust into a truck’s particulate matter aftertreatment 

device will not jeopardize the truck’s engine warranty. 
- 39 - 

Staff anticipates that two primary scenarios will occur with regards to the 

integration of APS and truck exhaust systems; an engine or truck manufacturer 

certifies a fully integrated APS and vehicle exhaust system, or a third party 

(aftermarket installer) routes the APS exhaust into a previously certified engine 

exhaust system configuration. Under the first scenario, the certifying entity 

(engine or truck manufacturer) must warrant the integrated exhaust system 

pursuant to applicable warranty provisions (Health and Safety Code sections 

43205 “Warranty requirements for light and medium duty motor vehicles) or 

section 43205.5 “Warranty for motor vehicles other than light and medium duty” 

and title 13, CCR section 2035 et seq.), and is therefore responsible for 

covering the entire integrated system under its warranty. 

Under the second scenario, an entity other than the engine manufacturer routes 

the APS’s exhaust stream into the vehicle’s particulate matter aftertreatment 

device. This modification must comply with the provisions of ARB’s on-road 

aftermarket parts regulation (Title 13, CCR section 2220 to 2225), which 

requires the entity to demonstrate that the modifications will not increase 

emissions compared to the baseline configuration, adversely affect the 

durability of the vehicle’s emission control system, or affect the proper 

operation of the vehicle’s on-board diagnostic system. If ARB exempts the 

modification from the prohibitions of Vehicle Code section 27156 and 38391, 

that modification cannot jeopardize the engine’s warranty. Title 13 CCR section 

2036(d)(10) [applicable to 1979 and subsequent heavy-duty vehicles and 

engines] and section 2037(d)(10) [applicable to 1990 and subsequent mediumduty vehicles and engines] provide: 

“Any add-on or modified part exempted by the Air Resources Board 

from the prohibitions of Vehicle Code section 27156 may be used on a 

vehicle or engine. Such use, in and of itself, shall not be grounds for 

disallowing a warranty claim made in accordance with this article. The 

vehicle or engine manufacturer shall not be liable under this article to 

warrant failures of warranted parts caused by the use of an add-on or 

modified part.” 

This modification does not require the vehicle engine manufacturer’s guidance 

and approval, because such guidance or approval is not a criterion in ARB’s 

determination whether to issue an aftermarket part applicant an exemption from 

Vehicle Code sections 27156 and 38391. 

37. Comment: It is not clear how internal combustion APSs will perform in the real 

world, and if they will be able to maintain their certified emissions level in the 

future. ARB should establish an in-use testing and inspection program (i.e., 

“smog check”) for such APSs after the implementation date of this regulation 

and should conduct bench tests and collect real-world data on APSs and main 

engine idling, including emissions, fuel usage, maintenance costs, and driver 

comfort. (CalETC) 
- 40 - 

Agency Response: Diesel-fueled APSs are equipped with small off-road 

engines and are therefore subject to ARB’s off-road engine certification process 

which verifies that the engine complies with the emission standards over its 

useful life. Also, diesel-fueled APSs, like other diesel off-road engines, will be 

subject to any future in-use compliance requirements that may be developed to 

ensure emission standards are complied with in-use. Staff does not believe it is 

currently necessary to collect other in-use test data or implement a complex 

smog check program for APSs to ensure proper in-use emissions performance. 

38. Comment: Both trucking businesses and equipment manufacturers need 

adequate time to test and evaluate compliance technologies. Ideally, fleets 

would like two years lead time to test and evaluate new equipment. Since APS 

manufacturers will have just over two years to develop compliant equipment (if 

feasible), fleets will not have adequate time to test and prove the reliability of 

2007+ trap-equipped APSs in over-the-road application. As a result, fleets are 

likely to hold onto their existing equipment longer in order to use the current 

APS technologies they are familiar with. (ATA) 

Agency Response: The Agency Response to Comment 34 is incorporated 

herein. Staff does not agree with the commenter’s statement that fleets will 

keep their pre-2007 trucks in order to use the current APS technology because 

other factors, such as engine mileage, warranty coverage, and operating costs 

are more likely to influence business decisions whether to retain or replace 

trucks. As stated in the Agency Response to Comments 31 through 33, this 

rulemaking does not require the use of a diesel APS, and a truck operator can 

choose to use any of the many alternative technologies available in the market. 

If the owner/operator does not want to spend money on these devices, he or 

she can adjust his schedule and find a truck stop that provides off-board 

climate control such as that provided by IdleAire Technology. 

39. Comment: The Board should direct staff to work with engine and emission 

control manufacturers to develop electronic fuel control and turbocharger 

systems for the under 25 hp diesel engines used in APSs. (Pony Pack). 

Agency Response: ARB staff will continue to perform their duties in 

developing air pollution control programs to protect the public health, and will 

participate in other activities as directed by the Board. This request to assist 

manufacturers in developing improved emissions control technologies is 

beyond the scope of ARB’s specified duties. 

40. Comment: The Board should fund Carl Moyer projects to assist in the 

development, testing, and eventual certification of aftertreatment technologies 

for small diesel engines. (Pony Pack) 

 Agency Response: The Carl Moyer Program funds the incremental cost of 

cleaner-than-required engines, equipment, and other sources of air pollution, 

but does not provide funds for developing, testing, or certification of emission 
- 41 - 

control technologies. However, Pony Pack may consider requesting funds 

through the Innovative Clean Air Technologies Program (ICAT), an ARB 

program that co-funds the demonstration of innovative technologies that can 

reduce air pollution. ICAT’s purpose is to advance such technologies toward 

commercial application, thereby reducing emissions and helping the economy 

of California. 

E. ELECTRICAL POWER BASED ALTERNATIVE TECHNOLOGIES

41. Comment: Parts of the Staff Report imply that truckers will (or must) decide to 

use onboard systems (primarily APSs) in response to the sleeper idling 

prohibition. We request clarification that the rule does not favor APSs or 

onboard systems over other technologies. Further, to avoid possible confusion, 

the rule should also clarify that it does not compel the installation of APSs or 

other onboard systems on heavy-duty trucks. We also request that the rule 

explicitly provide that on-shore electrical power is an acceptable alternative to 

idling. (IdleAire) 

 Agency Response: The rule clearly does not compel the installation of any 

device on heavy trucks. The primary compliance option of this rulemaking is 

for a trucker to simply manually shut down the truck engine after 5 minutes of 

idling, but the rulemaking also sets performance requirements for technologies 

that may be used as alternatives to engine idling. Any technology that meets 

those requirements can be used, including off-board technologies. 

Notwithstanding this, staff has modified the regulation to clarify that 

technologies utilizing on-shore electrical power or comparably clean emission 

technologies will be allowed as options to comply with the in-use idling 

regulations. 

42. Comment: Advance Executive Officer approval should not be required for 

battery powered APSs, power inverter chargers for on-shore electrical power, 

and on-shore electrical power, and other zero-emission technologies. (IdleAire, 

CalETC) 

Agency Response: As directed by the Board, staff has modified section 

2485(c)(3)(C) to clarify that a manufacturer using a battery powered APS, 

power inverter/charger for on-shore electrical power, or an electric 

infrastructure or comparably clean technology is not required to seek and 

receive advance Executive Officer approval before using such alternative 

technology. Subsequent to the hearing, staff determined that fuel cell APSs 

are also within the category of comparably clean technologies that should not 

require advance Executive Officer approval. 

43. Comment: The rule should encourage the installation and use of electrification 

equipment where it is available. After the rule’s effective date, if electrified 

parking spaces are available, trucks (including diesel APS equipped trucks and 
- 42 - 

trucks certified to the proposed optional NOx idling standard) should be 

required to shutdown and use the electric infrastructure. (IdleAire). 

Agency Response: No change was made in response to this comment. The 

rulemaking requires a truck operator to shut down the truck’s engine after 5 

minutes of idling, but allows engines certified to the optional NOx idling 

standard and trucks equipped with compliant APSs to continue idling. The rule 

does not otherwise restrict where trucks complying with the proposed 

requirements can or can not idle, except that idling is prohibited within 100 feet 

of a restricted area. The decision to shut down a truck and use an electrified 

parking space in lieu of the other compliance options specified in the 

rulemaking must be made by truck stop operators and fleet owners, not ARB. 

44. Comment: The effective date of the sleeper portion of the rule [in-use portion 

of the rulemaking] should be deferred until 2009. This would be consistent with 

an informal consensus reached last year regarding the need for a sufficient 

amount of time for truck stop electrification to be more widely deployed and for 

APSs to be more widely available. (IdleAire) 

 

45. Comment: Implementation of the sleeper truck provisions in January 2008 

would force truck owners to purchase diesel APSs, rather than encouraging 

cleaner and less-costly on-shore electrical power technology. The proposed 

implementation date does not provide sufficient time for on-shore electrical 

power to become widely deployed. We therefore recommend that the sleeper 

truck portion of the rule be deferred until September 2009. (CalETC). 

Agency Response to Comments 44 and 45: No change was made in 

response to these comments. Staff is opposed to postponing the in-use portion 

of this rulemaking until 2009. Staff is also not aware of any informal consensus 

reached in 2004 regarding the need for a sufficient amount of time for truck 

stop electrification to be more widely deployed and for APSs to be more widely 

available. Staff believes that the best way for IdleAire and truck stop 

electrification businesses to increase their market share is to introduce their 

product early and to deploy it widely. Even if truck stop electrification 

businesses install their products early, staff believes there will still be a high 

dependence on on-board cab comfort devices from truckers who park in areas 

where IdleAire’s product or electrified parking spaces are not available. 

Therefore, there is a definite limit on how much of the market truck stop 

electrification may be able to capture. Staff believes that the rulemaking’s 2008 

implementation date will further encourage the deployment of truck stop 

electrification and will help expedite the installation of those facilities. 

46. Comment: The proposal appears to allow battery-based and stop-start 

systems but the method and requirements for obtaining ARB approval are not 

clear. We assume that truck OEMs and autonomous system suppliers will be 

able to seek this approval. (TMA) 
- 43 - 

Agency Response: The Agency Response to Comments 35 and 36 is 

incorporated herein. The in-use component of this rulemaking allows 

battery-based and stop-start systems as alternatives to main engine idling. 

Title 13, CCR section 2485(c)(3)(C), as modified during the 15-day comment 

period, clearly provides that battery-based systems can be used without 

obtaining the Executive Officer’s prior approval. The same section also applies 

to automatic stop-start systems, which allows the use of other technologies 

subject to advance Executive Officer approval, and provided those other 

technologies are at least as effective in reducing idling emissions as a diesel 

APS equipped with a Level 3 verified PM device or the optional NOx idling 

standard. The entity seeking approval depends on whether the systems are 

installed on a vehicle before the legal or equitable title to the vehicle has been 

transferred to an ultimate purchaser (truck OEM) or whether they are installed 

after legal or equitable title has transferred (aftermarket installers). 

47. Comment: The ARB should seamlessly integrate its regulatory rulemakings 

with incentive programs (such as Carl Moyer incentive program) so that the 

Board, industry and other stakeholders can fully understand how they interact. 

A critical part of this is to clearly define the emissions baselines created by 

particular regulations so that surplus emissions of NOx, ROG, PM and green 

house gases (GHG) can be determined and clear for incentive programs. ARB 

staff should establish a clear and consistent baseline for emissions from truck 

idling reduction both prior to the implementation date of the proposed 

regulation, and after. (CalETC, IdleAire) 

Agency Response: The ARB typically does not integrate two entirely different 

programs into one rulemaking. The Carl Moyer Program has a much larger 

scope than this idling rule. Following the adoption of this regulation, the Carl 

Moyer funding guidelines were modified to define the new emission baselines 

and what constitutes surplus emissions to reflect the idling regulation. 

Assuming that there will be a high use of compliant diesel APSs for sleeper 

trucks, the guidelines establish the emission factors of the diesel APSs with 

Level 3 verified PM traps as baseline emissions. This means devices such as 

electric batteries that are cleaner than a compliant diesel APS will be eligible for 

Carl Moyer funding. 

48. Comment: ARB should convene a “working group” as soon as possible for 

interested stakeholders, and other state, federal, and local agencies to discuss 

how to encourage and facilitate truck stop electrification and other zeroemission idling reduction technologies and infrastructure. (CalETC) 

Agency Response: The ARB generally sets performance-based standards 

and therefore does not prefer one technology over another, as long as both 

technologies can meet the standards. By the same token, ARB cannot 

convene a “working group” selectively for one technology group in preference 

over other equally compliant technologies. However, if ARB is invited to join 

such working groups, it may certainly decide to participate in such groups. 
- 44 - 

F. COMPLIANCE COSTS

49. Comment: The proposed idling requirements are cost prohibitive and will 

cause financial hardships for businesses forced to comply. The ARB should 

provide financial assistance for affected businesses to cover the capital costs of 

compliance with the idling requirements. (CTA) 

50. Comment: The capital cost needed to comply with the idling regulation will 

create economic hardships for many trucking businesses, especially small 

business. Financial assistance is needed to help trucking businesses better 

absorb the added operating costs and to minimize these hardships. (ATA) 

51. Comment: CCEEB fully supports the idea that incentive programs such as Carl 

Moyer is integrated into rules and other regulations that are adopted. (CCEEB) 

52. Comment: Truck OEMs are offering (or will offer in the near future) auxiliary 

systems integrated into sleeper berth trucks. This should be incentivized, as 

California and other state and local governments are doing. (ATA)

Agency Response to Comments 49 through 52: The Agency Response to 

Comment 47 is incorporated herein. The ARB, through its Carl Moyer 

Program, currently provides financial incentives for the installation of idle 

reduction devices on long haul trucks, and has recently updated the Carl Moyer 

Program funding guidelines to reflect the requirements of this rulemaking. It 

should also be noted that in most cases, the initial capital costs of a compliant 

APS will be recouped in 2.5 or less years, due to the fuel savings resulting from 

reduced idling. Also see the Agency Response to Comments 53 and 54. 

Another program under development that may provide assistance to comply 

with the regulation is California Assembly Bill 1901. This bill would establish, 

until January 1, 2012, the Truck Retrofit Revolving Loan Program in the Energy 

Resources Conservation and Development Commission to help finance the 

retrofitting of trucks with the U.S. EPA SmartWay Upgrade Kits, including idle 

reduction technologies, that would be required to have specified emission 

control devices and may have other specified equipment. The bill has been 

passed by Assembly Committee on Transportation and by the Assembly 

Committee on Jobs, Economic Development and the Economy, and is currently 

before the Appropriations Committee. 

53. Comment: Many trucking businesses will not be able to afford the added 

capital costs of alternative idle reduction technologies to comply with the 

requirements. (ATA) 

54. Comment: Although the number of trucks stops that equip their parking spaces 

with auxiliary means of providing power to sleeper berth equipped trucks has 
- 45 - 

been increasing, it should be recognized that there will never be enough of 

these parking spaces – especially in all the locations where trucks stop. As a 

result, this rule will effectively require sleeper berth trucks to be equipped with a 

fully autonomous cab comfort systems. Costs for such systems range from 

$5,000 to $10,000. This is a significant investment for truck owners, and will 

closely follow the introduction of 2007 emissions-compliant engines and their 

own associated costs. Some truck owners will not have the financial capability 

to purchase fully autonomous systems. (TMA) 

Agency Response to Comments 53 and 54: Because of the growing demand 

for cab comfort devices due to idling restrictions and increasing fuel prices, staff 

now believes that the cost of an APS will be lower than the $5,000 to $10,000 

cost estimated in the Staff Report. This means that the pay back period would 

be much less than the 2.5 year pay back period previously estimated in the 

Staff Report. Furthermore, there are a number of incentive programs that 

trucking businesses can use to alleviate the financial burden imposed by this 

requirement. For incentive programs in California, see the Agency Response 

to comments 49 through 52. A number of other states also currently provide 

low interest loan programs or grants for the purchase of idle reduction devices. 

Refer to the U.S. EPA document “Model State Idling Law”8 for a summary of 

federal and state financial assistance programs. Staff believes these financial 

assistance programs and the expected short pay-back periods will motivate 

trucking businesses to equip their trucks with on-board cab comfort devices, or 

utilize truck stops with electrified parking spaces or IdleAire products rather 

than trying to sleep in their cab under unfavorable conditions. Thus, any safety 

issues related to sleeping in an uncomfortable environment can be avoided. 

G. LABELING REQUIREMENTS

55. Comment: The proposed labeling requirements are too much restrictive in 

terms of detailed design and size of the labels and their proposed location on 

the vehicle. If labeling becomes necessary, much smaller labels located under 

and/or behind the driver’s side door are more acceptable. (TMA)

Agency Response: No change was made in response to this comment. The 

labels are intended to aid enforcement personnel in clearly and easily 

identifying diesel engines certified to the optional NOx idling standard and 

diesel trucks equipped with compliant PM trap equipped APSs. Thus, the 

labels must be applied to a highly visible location of the truck, and their size and 

color must allow the label to be readily visible from a distance of 10 to 15 feet. 

The commenter’s proposal that the label be smaller in size and be located 

under or behind the driver’s side door will hinder effective enforcement and 

reduce the effectiveness of the regulation. 

 

8

 U.S. EPA “Model State Idling Law”, EPA420-S-06-001. April 2006. 

(http://www.epa.gov/smartway/documents/420s06001.pdf) 
- 46 - 

56. Comment: The labeling provisions in the ATCM portion of the rulemaking 

appear to conflict with “Section 4306 of the recently enacted federal highway 

bill” (H.R. 3, now P.L. 109-59), which bars states from requiring any form of 

identification to be displayed in or on a commercial motor vehicle, apart from 

several enumerated exceptions, none of which apply to the [proposed] 

emissions label.” (ATA)

Agency Response: As demonstrated below, the cited provision of the federal 

highway bill only pertains to state labeling requirements directly related to the 

registration of trucks and does not preempt the proposed labeling provisions in 

the ATCM portion of the rulemaking. 

Section 4306 (Title 49, U.S.C. section 14506) was enacted as a component of 

the “Unified Carrier Registration Act of 2005” set forth in Subtitle C of the Safe, 

Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users' 

or `SAFETEA-LU', (Pub. L. No. 109-59 (August 10, 2005) 119 Stat. 1144). 

See sections 4301 to 4308, (Pub. L. No. 109-59 (August 10, 2005) 119 Stat. 

1144). The Unified Carrier Registration Act replaced the prior federal statutory 

scheme applicable to commercial motor vehicle registration, the “Single State 

Registration System” (SSRS), Mid-Con Freight Systems, Inc. v. Michigan 

Public Service Com’n (2005) 125 S.Ct. 2427, 2430, Section 4305, Pub. L. No. 

109-59 (August 10, 2005) 119 Stat. 1144). 

In a case involving a preemption clause within the SSRS, the United States 

Supreme Court held the clause did not preempt a state law imposing a fee on 

trucks. Mid-Con Freight Systems (2005) 125 S.Ct. 2427, 2346. The Court 

rejected arguments that the clause should be interpreted broadly to preempt all 

individualized state registration requirements affecting a carrier, or state 

registration requirements imposed on carriers because of their operation in 

interstate commerce, and instead found that the clause (49 U.S.C. § 14504(b)) 

only preempted state requirements concerning the specific subject matter 

regulated by the federal statute - SSRS registration. Id. at 2432. The Court 

reasoned that neither the text, the statute’s basic purposes or its historical 

context required reading the clause broadly to impliedly pre-empt other nonSSRS related state rules. Id. at 2434. 

Shortly after the Mid-Con Freight Systems case was decided, the Unified 

Carrier Registration Act of 2005 was enacted to supersede the SSRS (section 

4304, Pub. L. No. 109-59 (August 10, 2005) 119 Stat. 1144) and to serve as a 

“comprehensive foundation for registration, insurance and safety information.” 

65 Fed. Reg. 35287, 35288 (June 2, 200). It is readily apparent from the text 

and purpose of the current Act that its scope is still strictly limited to motor 

vehicle registration requirements and its provisions regarding labeling only 

preempt inconsistent state laws concerning the specific subject matter 

regulated by the federal statute – vehicle registration. 
- 47 - 

First, the text of section 4306 (Title 49, U.S.C. section 14506) of the 

“SAFETEA-LU”, (Pub.L.No. 109-59 (August 10, 2005) 119 Stat. 1144), itself 

indicates that its preemptive scope is limited. 

Sec. 14506. Identification of vehicles

`(a) Restriction on Requirements- No State, political subdivision of a State, 

interstate agency, or other political agency of 2 or more States may enact 

or enforce any law, rule, regulation standard, or other provision having the 

force and effect of law that requires a motor carrier, motor private carrier, 

freight forwarder, or leasing company to display any form of identification 

on or in a commercial motor vehicle (as defined in section 14504a), other 

than forms of identification required by the Secretary of Transportation 

under section 390.21 of title 49, Code of Federal Regulations.

`(b) Exception- Notwithstanding subsection (a), a State may continue to 

require display of credentials that are required--

`(1) under the International Registration Plan under section 31704;

`(2) under the International Fuel Tax Agreement under section 

31705;

`(3) under a State law regarding motor vehicle license plates or 

other displays that the Secretary determines are appropriate;

`(4) in connection with Federal requirements for hazardous 

materials transportation under section 5103; or

`(5) in connection with the Federal vehicle inspection standards 

under section 31136.'. 

(b) Clerical Amendment- The analysis for such chapter is amended by 

inserting after the item relating to section 14505 the following:

Section 4305 is entitled “Registration of Motor Carriers by States,” and itself 

contains a preemption clause (Title 49, U.S.C. § 14504a(c)) that lists the 

same subject areas at issue in the Mid-Con Freight Systems case: state 

registration, registration of proof of financial responsibility, registration of an 

agent for service of process, registration of proof of insurance. 

Second, section 4302 of the same legislation (set out in a note to Title 49, 

U.S.C. section 13902) also limits the preemptive scope of the Unified Carrier 

Registration Act: 

SEC. 4302. RELATIONSHIP TO OTHER LAWS.

Except as provided in section 14504 of title 49, United States Code, 

and sections 14504a and 14506 of Title 49, United States Code, as 

added by this subtitle, this subtitle is not intended to prohibit any State 

or any political subdivision of any State from enacting, imposing, or 

enforcing any law or regulation with respect to a motor carrier, motor 

private carrier, broker, freight forwarder, or leasing company that is not 

otherwise prohibited by law. 
- 48 - 

While sections 4302, 4305 and section 4306(b) do not explicitly exempt state 

health and safety laws from section 4306(a), neither do they explicitly include 

them within the preemptive reach of 4306(a). This is also true of Title 49 

U.S.C. § 14504(b) and (c) at issue in the Mid-Con Freight Systems case. In 

that case, the U.S. Supreme court stated, “[s]imilarly, we see no language 

elsewhere in the statute suggesting that the term ‘State registration 

requirement’ refers to any kind of State Registration whatsoever that might 

affect interstate carriers. And even the Government concedes that certain 

registration obligations- those in ‘traditional areas of state regulation’ –are 

beyond the pre-emptive reach of the statute.” Mid-Con Freight Systems at 

2433. As discussed in section of this FSOR (agency responses to comments 

73 through 75), preventing air pollution is and has been a traditional local safety 

concern, Huron Portland Cement Co. v. Detroit (1960) 362 U.S. 440, 445-446, 

and the U.S. Supreme Court also recognizes that the Federal Motor Carrier 

Safety Administration has no statutory authority “to impose or enforce 

emissions controls or to establish environmental requirements unrelated to 

motor carrier safety.” Dept. of Transp. v. Public Citizen (2004) 541 U.S. 752, 

759. 

Finally, the forms of identification required by the Secretary of Transportation 

under section 390.21 of Title 49, Code of Federal Regulations only specify the 

“legal name or single trade name of the motor carrier,” 49 CFR 390.21(b)(1), a 

“motor carrier identification number,” 49 CFR 390.21(b)(2), and the name of the 

operating carrier, 49 CFR 390.21(b)(3). 49 CFR 390.21(b)(4) states “Other 

identifying information may be displayed on the vehicle if it is not 

inconsistent with the information required by this paragraph.” See also

discussion in 65 Fed. Reg. 35827, 35290-291 (June 2, 2000). “Concerning the 

questions raised by the NYSMTA about a local jurisdiction's requirement for 

listing a full street address, and the Missouri DMCSR's question about a State's 

requirement for the display of a GVW or GVWR on intrastate-only CMVs, any 

other identifying information may continue to be displayed, as long as it is not 

inconsistent with other § 390.21 requirements.” 

All of the above mentioned considerations support the ARB’s determination that 

the labeling provisions of the ATCM portion of the rulemaking are not 

preempted by Title 49, U.S.C. section 14506. 

H. REMOVAL OF SLEEPER TRUCK EXEMPTION

57. Comment: There are areas of the United States where it is hazardous to shut 

down the engine during winter, where temperatures can sharply drop in 

minutes, and a trucker cannot start the engine, which requires a specialist to 

heat the fuel tanks and engine block at the trucker’s expense over 12 to 36 

hours before the engine can start. A policy of limited idle time must be 

tempered with common sense. (Allen Lilleberg) 
- 49 - 

Agency Response: Recognizing the health and safety issues facing drivers 

during severe weather conditions, ARB has included in the rulemaking an 

exemption to allow the main engine to idle continuously during extreme weather 

conditions. For engines equipped with an engine shutdown system, the engine 

shutdown system can also be overridden to warm up the engine if the engine 

coolant temperature is below 60°F. Also, a truck operator may equip his truck 

with an on-board device that will provide cab comfort and engine heating during 

extreme weather conditions. 

58. Comment: Truck stops and travel plazas contribute significantly to California’s 

economy. ARB’s idling restriction proposal on sleeper berth trucks will place 

these important businesses at a competitive disadvantage with truck stop 

operators in neighboring states that exempt sleeper berth equipped trucks from 

idling restrictions. The ARB’s actions to limit idling to 5 minutes will force truck 

operators to limit their time in California in order to avoid the added costs of 

purchasing on-board cab comfort devices. Therefore, ARB should reconsider 

its proposal to limit idling of sleeper berth trucks to 5 minutes in the state of 

California. (Love’s Travel Stops, NATSO) 

Agency Response: Staff believes that trucking businesses, faced with 

increasing diesel fuel prices and idling restrictions, will be motivated to install 

on-board cab comfort devices or use truck stops equipped with plug-in 

capabilities rather than rush to neighboring states solely because they can idle 

the truck engine for cab comfort. Using cab comfort devices instead of idling 

the main engine will help truck operators save fuel costs and will provide them 

a better rest environment. Also, communities are increasingly realizing the 

harmful effects of diesel emissions and noise nuisance resulting from the 

extended idling of diesel trucks, which has resulted in a nationwide increase in 

state and local rules to limit truck idling. Thus, to also attain air quality 

standards and reduce fossil fuel consumption, staff expects that in the near 

future neighboring states or their local governments will adopt regulations to 

control extended idling of diesel trucks9

. Staff therefore does not expect that 

California’s idling requirements will place California’s truck stop operators at a 

competitive disadvantage with truck stop operators in neighboring states. In 

fact, staff believes that the rule will provide truck stop operators an additional 

revenue source if they choose to install alternative off-board cab comfort 

systems. 

59. Comment: The ARB has not allowed sufficient time for market forces to take 

effect. Many fleets will initially purchase a few alternative idling devices and 

then increase their purchases as they prove to themselves that those devices 

positively affect their operating costs and profitability. Since demand for 

alternative technologies is up due to increased fuel prices and incentives are 

 

9

 Two of California’s state neighbors, Arizona and Nevada, have adopted regulations that limit idling of diesel 

trucks, although sleeper trucks are exempted during federally mandated rest hours. The idling restrictions are 

contained in “Arizona Revised Statutes, Section 11-876”, for Arizona, and in “Nevada Administrative Code, 

Section NAC 445B.576”, for Nevada. 
- 50 - 

proving effective, we strongly encourage ARB to reconsider implementing this 

proposal. Alternatively, if ARB does proceed, that the sleeper berth exemption 

should be phased out over time, allowing the much lower emitting newer model 

year vehicles a longer exemption period beyond the 2008 effective date in the 

proposal. (TMA)

Agency Response: No change was made in response to this comment. If 

demand for alternative technologies is increasing due to increased fuel prices 

and incentives are proving effective, then this complements the effectiveness of 

the idling regulation. Phasing-out the sleeper berth exemption over time is not 

acceptable for two reasons. First, the new model year vehicles may be certified 

to low exhaust emission standards, yet may emit high levels of NOx emissions 

during idle modes. This is because the very low exhaust temperatures that 

exist during extended idling operations render the NOx catalysts ineffective. 

Second, since many sleeper trucks are based out-of-state, the proposed 

phase-out exemption would be difficult to implement and enforce. ARB does 

not accept the continued exemption of sleeper trucks nor does it agree with the 

proposal to phase-out the exemption. In addition, sleeper trucks’ contribution to 

NOx+ROG emissions is significant. ARB estimates that in 2010, extended 

idling emissions of NOx+ROG from sleeper trucks will be approximately 22 tons 

per day and 36 tons per day for trucks registered in California and out-of-state, 

respectively. 

60. Comment: The proposed engine shutdown system does not allow a driver to 

disengage the shut off system in case of an emergency situation necessitating 

the use of a heater or air conditioner. Since the proposed low NOx idle engine 

option is infeasible by 2008 and will not be available for purchase, truck owners 

will be forced to purchase trucks equipped with the shut off devices to comply 

with the idling requirements, endangering the health of drivers and risking 

public safety. 

Drivers of non-sleeper trucks generally will not be equipped with APS units, and 

the proposed regulation will prevent them from overriding the shutdown system 

in an emergency situation. Sleeper trucks will be discouraged from using shore 

power or other alternative technologies, because drivers will not be able to plan 

emergency situations without the use of APS and truck owners will not want to 

incur the costs of using both idle reduction technologies. CTA recommends 

that the ARB continue the existing exemption for trucks with sleeper berths. 

(CTA)

61. Comment: ARB’s requirement for a non-programmable, tamper resistant 5-

minute shutdown system will, in effect, eliminate current exceptions for safety 

or health emergencies and for adverse weather conditions unless frequent 

actions are taken by the driver or another party (in case a driver is not able to 

respond). By eliminating these exceptions for trucks sold in California 

beginning in 2008, drivers of these trucks may be subject to adverse impacts 

should emergencies arise. It does not appear ARB has given any 
- 51 - 

consideration to how these types of situations can be avoided to ensure driver 

safety. (ATA) 

Agency Response to Comments 60 and 61: Whether during an emergency 

situation or not, an operator of a sleeper or non-sleeper truck equipped with the 

engine shutdown system would be able to continuously idle the truck engine by 

depressing one of the foot pedals every 5 or 15 minutes, depending on whether 

the parking brake is engaged or not. If the truck is a sleeper truck, the truck 

owner may purchase the truck wired with a factory installed shore power plug-in 

unit and an on-board cab comfort device such as an APS, or may purchase the 

truck with an APS that is also wired to provide shore power electricity. This 

would enable the operator of the sleeper truck to rest in the sleeper berth 

comfortably anywhere, whether he/she is stopped on the roadside due to 

severe weather condition or parked at a truck stop with electrified parking 

spaces. 

If the truck is a non-sleeper truck, the truck is not expected to have an APS as 

the truck operator is not expected to sleep in the truck. However, the operator 

will still be able to operate the truck engine continuously at idle by pressing one 

of the pedals to override the engine shutdown system. The owner of the 

non-sleeper truck may also consider purchasing a truck that is certified to the 

low NOx idling standard since some manufacturers intend to make such trucks 

available for 2008 (see the Agency Response to Comment 3). Finally, 

implementation of the rule cannot be delayed since idling sleeper trucks 

contribute significantly to the air quality problem of the state (see the Agency 

Response to Comment 59). 

I. AIR QUALITY BENEFITS

62. Comment: The ARB has grossly overestimated the NOx reductions from 

implementation of the proposed rule. ARB used questionable and nonsensical 

high NOx idle emission rates. First, the various estimates for idle emission 

rates are based on idle emission data taken from trucks primarily during the 

period 1991 through 2003, with a significant portion of idle measurements 

between 1995 to 2002. As ARB is clearly aware, NOx emissions during this 

time period may be suspect. See Agenda Item 00-12-5. Therefore, use of 

these idle emissions is inappropriate for estimating idle emissions, especially 

after October, 2002. (International) 

Agency Response: The commenter does not specify why the idling NOx 

emissions during the period from 1991 to 2003 are suspect, nor is it clear how 

agenda item 00-12-5 (Amendments to Adopt Not-To-Exceed and Euro III 

European Stationary Cycle Emission Test Procedures for the 2005 and 

Subsequent Model Year Heavy-Duty Diesel Engines) relates to the statement 

that NOx emissions during this time period “may be suspect.” Staff cannot 

respond to an assertion that is not substantiated or clearly described. 

Nevertheless, staff will comment on the NOx idling emission rates used to 
- 52 - 

quantify the reductions. The idling NOx emission rates used in this regulation 

were derived from test data obtained from two sources: (1) the Coordinating 

Research Council E55/E59 Heavy-Duty Diesel Testing Project (CRC E55/E59), 

and (2) the joint U.S. EPA and Oak Ridge National Laboratory (ORNL) idle test 

program. These are peer-reviewed, published reports and are referenced in 

the Staff Report. Idle tests in the CRC E55/E59 program were conducted at 

curb idle without any loading, while the U.S. EPA/ORNL tests were conducted 

at different idle speeds (ranging between 600 rpm to 1200 rpm), different 

ambient conditions to simulate winter and summer conditions, and under 

different loading conditions (including no load, heating, and air conditioning 

load). These reports contain the best publicly available data and supported 

staff’s estimates of idle emission rates and emission reductions associated with 

the rulemaking. Also see the Agency Response to Comment 59. 

63. Comment: The use of such a high nonsensical idle emission rate fails to 

account for the significant emission reductions necessary to meet the new low 

emission standards in 2007 and even lower standards in 2010. The idle 

emission point within the 13-mode supplemental steady-state represents 15 

percent of the weighted composite. Contrary to ARB’s estimates, 

International’s own data suggests that, as standards decrease, idle emissions 

are also decreasing. Using data from a model year 2007 medium-duty 

development engine and ARB’s idle emission estimate of 115.3 grams per 

hour, the ARB idle estimate contributes 0.14 grams per brake horsepower hour 

to the total emissions. Such an idle emission rate, which represents 13 percent 

and 70 percent of the NOx standard in 2007 and 2010, respectively, would 

make it virtually impossible to meet the 2010 standard at an average idle 

emission level of 115.3 grams per hour. Therefore, the estimated emission 

reductions benefits are arbitrary and significantly overestimated. 

(International) 

Agency Response: The commenter has not provided data supporting its 

statement that its data indicates that NOx idling emissions decrease with a 

decrease in standards. The commenter also fails to provide specific 

information regarding how it arrived at the conclusion that an idling NOx 

emission rate of 115.3 grams per hour would contribute 0.14 grams per brake 

horsepower-hour. Without any data to substantiate these statements, staff is 

unable to adequately respond to this comment. Also, the NOx emission 

standards are in grams per horsepower-hour. It is understood that the idle 

emission contribution to the total emissions in the transient and steady state 

tests is very small because the engine load, and thus work, is very low. The 

commenter’s analysis of idle emissions at the 115.3 grams per hour rate does 

not make sense, since the certification emission test results are on a gram per 

horsepower-hour basis, not a gram per hour basis. Staff therefore disagrees 

with the assertion that the estimated emission reductions are arbitrary and 

significantly overestimated. 
- 53 - 

64. Comment: Trucking companies will keep their older trucks longer to avoid 

purchasing trucks with a combined APS/ PM aftertreatment system, which has 

not yet undergone thorough testing and will add a significant cost to new truck 

purchases in 2008. Instead, pre-2007 trucks will be kept on the road longer so 

that trucking companies can use existing, proven APS technologies. This will 

counteract much of the expected PM benefits from the 2007 engine standards. 

(CTA, ATA).

Agency Response: Staff disagrees with this assessment. Other factors such 

as engine mileage, warranty coverage and operating costs are more likely to 

influence business decisions whether to retain or replace trucks. Even if 

trucking companies want to avoid purchasing trucks with a combined APS/PM 

aftertreatment system, there are a number of other alternative technologies, 

such as battery based APSs, thermal energy storage, and others they can 

purchase with a new truck. Furthermore, staff believes that trucking 

businesses will not avoid purchasing new trucks with integrated APS/PM 

aftertreatment systems because such systems will be verified and warranted for 

their useful lives by the manufacturer, and offer substantial operating savings. 

65. Comment: The idling regulation allows APSs to vent their exhaust emissions 

through the truck’s main engine PM aftertreatment exhaust system. Exhaust 

emissions from the main engine are held to strict federal compliance standards 

which include minimum requirements for durability and effectiveness. As the 

peer-reviewed science behind the venting of APS emissions through the main 

engine exhaust system appears to be lacking, the impact of this venting on 

federally certified main engine exhaust systems, as well as their effectiveness 

of these systems during APS use is uncertain. (ATA) 

Agency Response: The Agency Response to Comments 35 and 36 is 

incorporated herein. Assuming for purposes of this response that in the 

absence of the idling regulation, a truck operator of a 2007 truck would idle the 

engine for extended periods of time to provide cab comfort. Staff estimates the 

engine-out PM emissions during idling of a PM trap equipped 2007 truck to be 

approximately 1.6 grams per hour. It is expected that the truck’s main PM trap 

would be designed to safely reduce engine-out PM emissions with minimum 

back pressure build-up during this extended idling period. It is also assumed 

that in the presence of an idling restriction, the truck operator would use a 

diesel-fueled APS to provide cab comfort. The PM emission rate of a Tier 4 

APS engine emitting at the standard and providing an average of 3 kilowatt 

power is estimated to be 1.2 grams per hour. If the APS exhaust is routed 

through the truck’s main PM trap, the performance of the main PM trap is not 

expected to change, since the APS engine PM emission rate is almost equal or 

even less than the truck engine-out PM emission rate. The commenter’s 

concern that the effectiveness of integrating engine/APS exhaust systems is 

uncertain is simply unsubstantiated. 
- 54 - 

66. Comment: As documented by the empirical observations contained in the 

“Weekend Ozone Effect” (Journal of Air and Waste Management Association, 

2003, 53 (7) 802-815), decreases in NOx emissions, mostly from fewer truck 

emissions, was the largest single contributor to elevated weekend ozone in the 

South Coast Air Basin. Decreases in NOx emissions did not reduce ambient 

levels of particulate-phase nitrate either. Consequently, emission reductions 

associated with the idling regulation have the potential to increase ozone 

formation. (ATA) 

Agency Response: The ozone weekend effect is not a reliable indicator that 

NOx control is counter-productive for reducing ambient ozone levels. The ARB 

conducted studies on the Ozone Weekend Effect10 and came to the conclusion 

that the weekend effect is not a real-world test of California’s NOx control 

program. California’s ozone control program has been effective all days of the 

week, although at a slightly slower rate on weekends than weekdays. NOx 

reduction may be one possible explanation for the weekend effect. However, 

the ARB’s studies concluded that it may not be the primary cause in some 

areas and other processes may have significant roles. Plausible causes for the 

weekend effect include NOx reduction, different timing of emissions including 

NOx, different amounts and impacts of pollutants that persist overnight aloft, 

different amounts of light-absorbing particulate matter in the air, ozone 

quenching by nitric oxide emissions, or some combination of these five factors. 

Significant uncertainties remain as to the causes of the ozone weekend effect 

and to the relevance of those causes on a long-term control strategy. 

Therefore, the conclusion that emission reductions associated with the idling 

regulation will have the potential to increase ozone formation is 

unsubstantiated. 

NOx is a key precursor not only of ozone, but also PM and other compounds 

with health and environmental concerns. These include nitrogen dioxide (NO2), 

nitric acid (HNO3), nitrous acid, peroxyacetylnitrate (PAN), nitro-polycyclic 

aromatic hydrocarbons (nitro-PAHs), regional haze, and nitrate deposition with 

subsequent fertilization and eutrophication of soils and surface waters. Many 

studies indicate that PM, in particular, but also NO2, HNO3, and other nitrogen 

containing pollutants have adverse health impacts, sometimes even greater 

than ozone episodes. Therefore, NOx control is also important for the large 

health benefits from reductions in other NOx-related pollutants. NOx reductions 

are also needed in ozone non-attainment regions that are not always HClimited. 

67. Comment: The ARB disregards advances in NOx adsorber technologies and 

in advanced engine controls that will also control NOx and system 

regeneration, and the resulting thermal loading on catalysts. Overall, NOx 

emissions for short duration idle periods will be zero or low for non-sleeper 

 

10 The Ozone Weekend Effect in California – Staff Report, Technical Support Document, and Appendices; 

ARB, Research and Planning and Technical Support Division, June 3, 2003. 

http://www.arb.ca.gov/aqd/weekendeffect/weekendeffect.htm
- 55 - 

trucks. Since ARB’s own data shows that non-sleeper trucks and medium duty 

trucks idle for minimal time during the day and that these vehicles will emit 

virtually no NOx during these short periods (<15 minutes), ARB should exempt 

these vehicles from this regulation. (International). 

Agency Response: Staff did not disregard the effects of advanced engine 

controls and thermal loading on catalysts, including NOx adsorber 

technologies, in controlling NOx emissions. Staff considered the effect of 

catalyst thermal loading on NOx emissions during idling and determined that 

catalysts remain hot and control NOx emissions during the first 5 minutes of 

idling following an end of a trip. However, after the first 5 minutes, the catalyst 

cools down to below its light-off temperature, during which time period it is no 

longer effective in controlling NOx emissions. A non-sleeper truck idles an 

average of 41 minutes per day, while a medium-duty truck idles an average of 

17 minutes per day, indicating a significant portion of the idling is not controlled 

by the NOx catalyst. Furthermore, not all idling events start at the end of a trip 

when NOx catalysts are still above their light-off temperatures and capable of 

reducing emissions. Some operators start the engine “cold” and keep the 

engine idling for extended periods of time, either to warm up the engine or to 

sleep in their cab. Therefore, the effect of catalyst thermal loading is negligible 

in controlling cold start idling NOx emissions and the commenter’s conclusions 

and request to exempt non-sleeper and medium-duty trucks is unacceptable. 

68. Comment: The proposal fails to adequately address the PM emission 

reduction necessary to meet the 2007 and later requirements with the low NOx 

emissions and idling periods of non-sleeper trucks. The current proposal 

assumes a PM idle emission rate of 0.16 grams per hour for 2007 and later 

engines, while the in-use idling ATCM rulemaking (agenda item 04-7-3) was 

based upon an estimated PM emission rate of 2.77 grams per hour. The in-use 

idling ATCM reviewed the risks associated with PM idle emission levels of 2.77 

grams per hour and 0.3 grams per hour, and found that the risks associated 

with PM levels of 0.3 grams per hour were significantly lower than that 

associated with PM levels of 2.77 grams per hour. At an emission level of 0.16 

grams per hour, this risk would again be significantly reduced. Since 

non-sleeper trucks idle for a much shorter period of time with little or no NOx 

emissions and ARB’s estimate of 0.16 grams per hour is approximately 50 

percent of that reviewed, but not used as a basis by the in-use idling ATCM 

rule, ARB’s failure to adequately and appropriately eliminate (or alternatively 

reduce) the idling restriction for DPF equipped trucks is arbitrary and 

capricious. (International)

Agency Response: No change was made in response to this comment. The 

risk associated with a PM level of 0.16 grams per hour is clearly less than that 

associated with a PM level of 0.3 grams per hour or 2.77 grams per hour. 

However, this does not mean that such risk is negligible or non-existent. Diesel 

particulate matter has been identified as a toxic air contaminant for which there 

is no safe threshold level of exposure. In addition to the health risks posed by 
- 56 - 

diesel PM, idling trucks also emit significant NOx emissions and other toxics 

regardless of whether the truck is equipped with a filter or not. NOx is one of 

the two primary contributors to the formation of ozone and contributes to 

serious public health issues. Thus, ARB’s action to restrict idling of filter 

equipped trucks is an appropriate measure that is designed to protect the 

public’s health and it disagrees with the commenter’s statement that ARB failed 

to adequately and appropriately exempt filter equipped trucks from the idling 

restriction or reduce their idling restrictions. 

69. Comment: ARB staff assumes that all sleeper trucks will comply with the 

proposed regulations beginning in 2008 by purchasing and installing a diesel 

APS, with Level 3 PM control for 2007 and later trucks, at a cost of $10,000 

each. But truck stop electrification, or other zero emission technologies, would 

provide even greater emissions reductions, at a lower cost to the truck owner. 

(CalETC) 

Agency Response: In estimating the emission benefits of this rulemaking 

resulting from the idling restrictions applicable 2008 and newer sleeper trucks, 

staff assumed these trucks will use a diesel APS with a level 3 PM control 

strategy. Staff’s assumption does not mean that all of these trucks will 

necessarily comply by purchasing diesel APSs. The purpose of this 

assumption was only to determine emissions benefits under the worst case 

scenario that assumes full compliance using diesel APSs. However, staff 

agrees that it if a truck uses a zero emission technology, then the benefits 

would be greater. 

J. LEADTIME AND STABILITY REQUIREMENTS

70. Comment: The new engine idling shutdown timer requirement is a new motor 

vehicle emission standard subject to the federal preemption and waiver 

provisions of the federal Clean Air Act (CAA). Section 202(a)(3)(C) of the CAA 

specifies that no new emission standard may take effect earlier than 4 model 

years after it is promulgated (“lead-time” requirement), or before the prior 

emission standard has been in effect for at least 3 model years (“stability” 

requirement). This requirement does not comply with either the lead-time or 

stability requirements. It violates the lead-time criteria because it takes effect in 

the 2008 model year, less than two model years from its date of adoption. In 

addition, heavy-duty on-highway engines will be subject to new emission 

control requirements applicable to 2007 through 2010 model year engines. 

Therefore, the CAA’s stability requirement prevents ARB from imposing any 

new emission control requirements until 2013. (EMA, CTA, Cummins)

Agency Response: The ARB has not yet conclusively determined whether the 

new engine idling shutdown timer requirement constitutes a standard relating to 

the control of emissions from new motor vehicle engines, which requires 

issuance of a new waiver from section 209(a) of the CAA, an amendment within 

the scope of an existing waiver, or an in-use operational control. This 
- 57 - 

requirement can be characterized as an in-use operational control not subject 

to preemption as a standard under Clean Air Act section 209(a) because it 

essentially implements through a mechanical means controlling in-use idling of 

on-road diesel trucks. Clean Air Act section 209(d) provides that California and 

other states are not precluded from controlling, regulating or restricting the 

“use, operation, or movement of registered or licensed motor vehicles.” As the 

Clean Air Act expressly allows states to impose the categories of controls 

specified in section 209(d), waiver of preemption is not at issue and the leadtime and stability provisions of Clean Air Act section 209(a)(3)(C), which apply 

to standards adopted by U.S. EPA, do not apply to this requirement. 

 However, for the purpose of responding to these comments ARB is assuming 

this requirement is a new motor vehicle engine emission standard. Based on 

this assumption, even if a new waiver from section 209(a) of the CAA is 

required, the lead-time and stability provisions of section 202(a)(3)(C) of the 

CAA do not apply to the new engine requirement. Section 202(a)(3)(C) only 

applies to standards “promulgated or revised under this paragraph [section 

202(a) of the CAA],” that is, to standards promulgated by the Administrator of 

the U.S. EPA. Since ARB adopted the new engine requirement pursuant to 

authority of California state law and the waiver provisions of section 209(b) of 

the CAA, the lead-time and stability requirements are simply inapplicable. 

Moreover, the Board directed staff that to the extent it is necessary, to either 

request a waiver or a confirmation that the regulations are within the scope of 

an existing waiver of federal preemption pursuant to section 209(b) of the CAA. 

Also, since 1970, U.S. EPA has typically applied a “2-pronged” test of whether 

California standards are consistent with CAA section 202(a) as required by 

section 209(b)(1)(C). The standards must be: (1) technologically feasible in 

the lead time provided considering the cost of compliance, and (2) compatible 

with the federal test procedures so that a single vehicle could be subjected to 

both tests. No more should be required. This is in accord with the legislative 

history of section 209. When the California waiver provisions and the 

“consistent with section 202(a)” language were first placed in the CAA in 1965, 

section 202(a) consisted of just one sentence requiring adequate lead time in 

consideration of technological feasibility and economic costs. In the 1977 CAA 

amendments, Congress amended section 209 “to afford California the broadest 

possible discretion in selecting the best means to protect the health of its 

citizens and the public welfare.” (H. R. Rep. No. 294, 95th Cong., 1st Sess. 301 

(1977), reprinted in 4 Leg. Hist. at 2768.) At the same time, Congress 

expanded section 202(a) to add several directives to U.S. EPA regarding its 

adoption of emission standards, including the 4-year lead time requirement for 

heavy-duty vehicles. Given Congress’s expressed intent to strengthen the 

waiver provisions, it is unlikely Congress intended to apply the specific 4-year 

requirement to California. 

Moreover, the Board directed staff, to the extent it is necessary, to either 

request a waiver or a confirmation that the regulations are within the scope of 
- 58 - 

an existing waiver of federal preemption pursuant to section 209(b) of the Clean 

Air Act. 

Finally, ARB believes that the commentators are misreading section 

202(a)(3)(C)’s stability requirement. That section simply states that any 

standard promulgated under 202(a) shall apply “for a period of no less than 3 

model years,” and does not support an interpretation that limits the U.S. EPA’s 

authority to regulate heavy-duty vehicles or engines to once every three model 

years. 

71. Comment: The alternative NOx idling emission standard violates the lead-time 

and stability provisions of the federal CAA. (Cummins)

 Agency Response: Please see the Agency Response to Comment 70. 

72. Comment: The provision in the ATCM portion of the regulation allowing the 

use of diesel-fueled APSs retrofitted with a verified Level 3 in-use strategy for 

particulate matter fails to provide the lead-time required in the federal CAA 

sections 213(b) [42 USC 7547(b)] and 209(e)(2) [42 USC § 7543(e)(2)]. (EMA)

Agency Response: Section 213(b) of the federal CAA provides “[s]tandards 

under this section shall take effect at the earliest possible date considering the 

lead time necessary to permit the development and application of the requisite 

technology, giving appropriate consideration to the cost of compliance within 

such period and energy and safety.” However, this section only applies to new 

nonroad engine and vehicle emission standards promulgated by the 

Administrator of the U.S. EPA, see e.g., §§ 213(a)(1)-(5), and not to the ATCM 

portion of the idling regulation that was promulgated under authority of state law 

and possibly the waiver provisions of the CAA section 209(e)(2). 

Section 209(e)(2) provides that the Administrator of the U.S. EPA shall 

authorize California to adopt and enforce standards and other requirements 

relating to the control of emissions from nonroad engines or vehicles unless he 

finds, among other things, that those standards and accompanying 

enforcement procedures are not consistent with section 209. Staff anticipated 

that the ATCM portion of the idling regulation might require an authorization 

from U.S. EPA under section 209(e), and therefore included language in 

Resolution 05-55 that “to the extent necessary, the Board directs the Air 

Resources Board staff to file a request for authorization ... pursuant to Clean 

Air Act section 209(e)(2).” Accordingly, if ARB submits an authorization, the 

Administrator of the U.S. EPA will determine, among other issues, whether the 

option regarding the use of diesel-fueled APSs equipped with level 3 PM traps 

is consistent with section 209 of the CAA, which in turn involves a 

determination whether sufficient lead time exists to permit the development of 

technology necessary to meet the standards and other requirements, giving 

appropriate consideration to the cost of compliance in the time frame provided. 

Also, U.S. EPA regulations specifically allow California to adopt nonroad 
- 59 - 

regulations prior to receiving authorization from U.S. EPA. 59 Fed. Reg. 

36969, 36981-983. (July 20, 1994).

K. FEDERAL HOURS OF SERVICE COMMENTS

73. Comment: The current idling ATCM exempts sleeper-berth equipped trucks 

from the five minute idling limit so that these trucks can power heaters, air 

conditioners or ancillary equipment. Eliminating this exemption will endanger 

the health and safety of sleeper-berth truck drivers because APSs equipped 

with Level 3 verified particulate matter systems are not feasible by the 2008 

timeframe of the regulation and because it is unlikely that all sleeper cab trucks 

entering California can or will be equipped with APSs or other climate control 

technologies by 2008. Consequently, sleeper-berth truck drivers will be forced 

to sleep and rest in uncomfortable cabs, which will adversely affect their health 

and safety, and ultimately the public’s safety as well. (EMA, DDC)

74. Comment: Federal regulations prescribe the maximum number of hours that 

drivers may operate trucks (hours of service or HOS) in a given time period. 

The HOS regulations include provisions allowing drivers to obtain mandatory 

hours of rest by sleeping in sleeper berth equipped trucks. 

Because trip planning is an inexact science, drivers cannot ensure they will 

always have ready access to hotels, electrification facilities or truck stops. In 

addition, some businesses will not be able to afford the regulation’s primary 

compliance option (APS + particulate trap) which ARB staff estimated will cost 

$5,000-$10,000 per truck. Those businesses need to decide whether to either 

discontinue doing business in California or “operate in the state without 

operating the main engine.” Truck drivers who shut down their vehicles while 

resting are likely to experience less than desirable sleeping operations, which 

will not allow them to obtain the adequate rest envisioned by the federal HOS 

regulation. (ATA, TMA, CTA, DDC)

Agency Response to Comments 73 and 74: The Agency Response to 

Comment 27 is incorporated herein. 

The Federal Motor Carrier Safety Administration (FMCSA) promulgates 

regulations limiting the number of hours that drivers may operate commercial 

motor vehicles. These regulations are commonly referred to as the “Hours of 

Service” (HOS) rules. The HOS rule was last revised on August 25, 2005, and 

became effective on October 1, 2005. See 70 Fed. Reg. 49978 (Aug. 25, 

2005). As explained in the Executive Summary portion of the HOS rule: 

“Today’s rule requires all drivers of property-carrying commercial 

vehicles (CMV’s) in interstate commerce to take at least 10 

consecutive hours off duty before driving, limits driving time to 11 

consecutive hours within a 14-hour, non-extendable window after 
- 60 - 

coming on duty, and prohibits driving after the driver has been on duty 

60 hours in 7 consecutive days or 70 hours in 8 consecutive days. 

Drivers may restart the 60-or 70-hour ”clock” by taking 34 consecutive 

hours off-duty.” 70 Fed.Reg. 49980 (Aug. 25, 2005). 

The HOS rule contains provisions allowing drivers of sleeper berth equipped 

trucks to accumulate rest periods in the sleeper berths. 49 CFR 395.1(g). 

Drivers that elect to use this provision must spend at least 8 consecutive hours 

in the sleeper berth and 2 consecutive hours either in the sleeper berth, offduty, or any combination of the two options. 

The comments imply that the proposal to eliminate the current idling exemption 

for sleeper-berth equipped trucks will impair the rest periods of those drivers of 

trucks not equipped with APSs, by prohibiting them from idling the main engine 

for cab climate purposes. The comments therefore necessarily imply that the 

idling regulation conflicts with (and is preempted by the federal HOS rule). 

The idling regulation is not inconsistent with the federal HOS rule and is 

therefore not preempted. In deciding whether a state law conflicts with, and is 

therefore preempted by a federal law, a court will first determine whether the 

state law is expressly preempted. If it is not, the inquiry then turns to whether 

Congress implicitly intended to preempt the state law or if the state law is 

preempted because it actually conflicts with the federal law. Chevron U.S.A., 

Inc. v. Hammond (1984) 726 F.2d 483, 486. In this case, the federal HOS rule 

contains no language stating that state idling reduction laws are preempted, so 

the idling regulation is not explicitly preempted, and the question then turns to 

whether the regulation actually conflicts with a valid federal law. 

The idling regulation does not actually conflict with federal law 

 

An actual conflict exists if compliance with both federal and state standards is a 

physical impossibility Florida Lime & Avocado Growers, Inc. v. Paul (1963) 373 

U.S. 132, 142-143, or if the state law stands as an obstacle to accomplishment 

and execution of the full purposes and objectives of Congress. Hines v. 

Davidowitz (1941) 312 U.S. 52, 67. A truck operator can clearly physically 

comply with both the proposed idling regulation and the federal HOS rule. For 

instance, drivers of sleeper berth equipped vehicles can shut off the main 

engine before resting 8 consecutive hours in the sleeper berth, or can start a 

compliant APS equipped with a verified level 3 PM trap to power cab climate 

accessories before occupying the sleeper berth. Furthermore, both the federal 

HOS rule and the idling regulation can be enforced “without impairing the 

federal superintendence of the field,” Chevron U.S.A., Inc. (1984) 726 F.2d 483, 

497. The HOS rule is intended to enhance commercial motor vehicle safety by 

preventing driver fatigue, and the idling regulation is designed to limit the 

emissions of air pollutants and toxic air contaminants from in-use sleeper trucks 

and new heavy-duty diesel vehicles. In light of the fact that the federal and 

state laws regulate entirely separate fields – the safe operation of commercial 
- 61 - 

motor vehicles and limiting air pollutant emissions generated from the idling of 

those vehicles, it is unlikely that Congress intended that the HOS rule preempt 

a state environmental regulation such as this idling regulation. 

 The idling regulation is not implicitly preempted by the federal HOS rule 

Finally, the idling regulation is not implicitly preempted by federal statutes 

authorizing the HOS rule – the Motor Carrier Act of 1935 and the Motor Carrier 

Safety Act of 1984. 70 Fed. Reg. 49979 (Aug. 25, 2005). A federal court 

deciding an implied preemption issue starts with the assumption that the state 

law is not preempted unless that was “the clear and manifest purpose of 

Congress.” Rice v. Santa Fe Elevator Corp. (1947) 331 U.S. 218, 230. Such 

intent is not likely to be found here. First, the HOS rule and the idling regulation 

regulate entirely different fields, motor vehicle safety and motor vehicle and 

nonroad exhaust emissions, respectively. Second, a state’s enactment of an 

environmental regulation, such as the idling regulation at issue, is accorded an 

enhanced presumption of non-preemption. Chevron U.S.A., Inc. 726 F.2d 483, 

488. Third, a provision in the federal motor vehicle statute, 49 U.S.C. 30103(b) 

only specifically prohibits states from prescribing motor vehicle safety standards

that are inconsistent with standards in effect under [Chapter 301, Subtitle VI, 

Title 49, United States Code]. These considerations therefore do not establish 

a pervasive federal regulatory scheme giving rise to an inference that Congress 

left no room for states to supplement it, or regulate the field of state 

environmental protection where the federal interest is so dominant that as to 

preclude state enforcement, especially in light of the sections 209(a) and (e) of 

the federal CAA waiving federal preemption for California’s new motor vehicle 

and nonroad sources, respectively. 

 Finally, several of the comments are premised on the assumption that many 

 truckers cannot afford APSs, which appears unlikely given their short projected 

 payback periods. As more fully explained in the staff report, staff projects the 

 cost of installing a compliant APS can be recouped within 2.1 years from the 

 savings in fuel costs. Staff therefore anticipates that the vast majority of 

 sleeper-berth equipped trucks will either be equipped with an APS or will utilize 

 another approved idling compliance option (e.g., truck stop electrification). 

L. COMMERCE CLAUSE COMMENTS

75. Comment: The regulation violates the Commerce Clause of the United States 

Constitution. (ATA, CTA) 

Agency Response: As explained below, neither the new engine idling 

shutdown timer nor the in-use ATCM component of the idling regulation violates 

the federal Commerce Clause. 

Article I, §8, cl. 3 of the United States Constitution states that the Congress has 

the power “[t]o regulate Commerce ... among the several States.” Courts have 
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long recognized that this affirmative grant of power also includes an implicit or 

“dormant” limitation on the authority of states to affect interstate commerce. 

Healy v. Beer Institute (1989) 491 U.S. 324, 326 fn 1. 

The threshold issue to be resolved in a Commerce Clause challenge to a state 

law is whether Congress has exempted that law from Commerce Clause 

scrutiny. In this case, Congress’ enactment of the federal Clean Air Act (CAA) 

provisions allowing only California to adopt and enforce new vehicle emission 

standards in § 209(b), and new and in-use nonroad engine standards and 

emission-related requirements in § 209(e)(2)(A) of the federal CAA, clearly 

evidence its intent to exempt California’s on and off-road vehicle and engine 

standards and emission-related requirements from Commerce Clause 

restrictions. The legislative history of the federal Clean Air Act indicates that 

Congress was fully aware that allowing states to establish their own motor 

vehicle emission standards would disrupt interstate commerce, and it therefore 

preempted the states from establishing their own motor vehicle emission 

standards. However, Congress specifically exempted only California from the 

federal CAA section 209(a) preemption. “Rather than being faced with 51 

different standards, as they had feared, or with only one, as they had sought, 

manufacturers must cope with two regulatory schemes under the legislative 

compromise embodied in § 209(a).” Engine Mfrs Ass’n v. U.S.E.P.A. (1996) 88 

F.3d 1075, 1079. See also Motor and Equipment Mfrs. Ass’n, Inc. v. E.P.A. 

(1979) 1095, 1108 – 1111. Congress determined that authorizing California to 

establish separate and more stringent standards than those applicable to the 

rest of the nation would not unduly disrupt interstate commerce. Instead of a 

Commerce Clause review, Congress enacted in section 209(b) of the federal 

CAA a procedure requiring the Administrator of the U.S. EPA to review 

California’s regulations and to authorize it to adopt and enforce its unique 

emission standards and other requirements. People ex rel. State Air 

Resources Bd. v. Wilmshurst (1999) 68 Cal.App.4th 1332, 1345, Jordan v. 

Department of Motor Vehicles (1999) 75 Cal.App.4th 449, 463. 

In the 1990 amendments to the federal Clean Air Act, Congress authorized the 

U.S. EPA to regulate nonroad sources of emissions. As with motor vehicles, 

Congress preempted all states but California from regulating nonroad sources. 

California is authorized to adopt and enforce both new and in-use nonroad 

emission standards and emission-related requirements, subject to the review of 

the Administrator of the U.S. EPA in § 209(e)(2)(A) of the federal CAA. In fact, 

the Court of Appeals for the D.C. Circuit has held that only California is 

authorized to adopt in-use requirements for nonroad sources. Engine Mfrs 

Ass’n v. U.S.E.P.A. (1996) 88 F.3d 1075. Other states that elect to regulate 

nonroad sources may only adopt regulations identical to those adopted by 

California, § 209(e)(2)(B) of the federal CAA. Therefore, both the text and 

history of the motor vehicle and nonroad preemption and waiver provisions of 

the federal Clean Air Act evidence Congress’ intent to exempt the requirements 

at issue from Commerce Clause scrutiny. In addition, even if a court were to 

hold that a waiver of preemption does not preclude it from determining if a state 
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law unpermissibly violates the Commerce Clause, as demonstrated in the 

Agency Responses to Comments 75a through 77a below, this rulemaking does 

not violate the federal Commerce Clause. 

75a. Comment: In determining whether a particular state law violates the federal 

Commerce Clause, a court follows a two step analysis. First, the court 

determines if the law discriminates against interstate commerce. If the law 

does, the state must demonstrate that the law “serves a legitimate public 

purpose” and that this purpose could not be served by less discriminatory 

means. 

The ATCM portion of the idling regulation violates the Commerce Clause of the 

United States Constitution. In analyzing whether a flat state tax discriminates 

against interstate commerce, courts examine the tax’s effect in relation to the 

level of the taxpayer’s in-state activity. American Trucking Association, Inc. v. 

Scheiner, (1987) 483 U.S. 266. In Scheiner, the Court held a flat state tax that 

cost out-of-state trucks five times more per mile than in-state trucks was invalid 

because it discriminated in effect against interstate commerce. The ATCM 

portion of the idling regulation can be construed as a tax on trucks operated in 

California. ARB staff estimates that an APS will cost $5,000-$10,000 per truck 

(staff report, p. 38). The effective cost of the APS on a California activity basis 

(per-mile, per-hour of operation, etc.) will likely be much higher for nonCalifornia based truck fleets than California based truck fleets. Therefore, the 

regulation can be analogized to a flat, annual state tax that the U.S. Supreme 

Court held violated the federal commerce clause because it discriminated in 

practical effect against interstate motor carriers. (ATA) 

Agency Response: The commenter’s analysis is flawed. Analogizing the 

ATCM portion of the idling regulation to a flat annual state tax is inappropriate 

because the regulation cannot reasonably be characterized as a tax, and 

because such assertion entirely disregards the local health and welfare aspect 

of the idling regulation. Furthermore, the ATCM portion of the rulemaking does 

not impose burdens on interstate commerce that are qualitatively or 

quantitatively different than those imposed on intrastate commerce. 

Merriam Webster’s Collegiate Dictionary, 10th edition, (1995) defines tax as “a 

charge usually of money imposed by authority on persons or property for public 

purposes,” or “a sum levied on members of an organization to defray 

expenses,” and these definitions are consistent with those widely applied by 

courts in cases analyzing if state taxes of motor carriers violate the federal 

Commerce Clause. “The word ‘tax’ is used herein in the generic sense in 

which it has come to be applied to most payments exacted by a state from 

particular industries as a condition to their existence. It includes fees required 

for licenses, permits, and registrations.” State Taxation of Motor Carriers as 

Affected by Commerce Clause, 17 A.L.R.2d 421. Here, it is undisputed that the

ATCM portion of this rulemaking does not impose any fee or payment as a 

condition of compliance - a truck operator needs only to manually shut off the 
- 64 - 

main truck engine after five minutes of idling. Furthermore, the provision 

regarding APSs merely provides an option that companies may elect to utilize. 

The decision to buy and install an APS is a business decision that each entity 

subject to this regulation will need to make for each truck that operates in this 

State, and the fiscal consequences for each company will obviously depend on 

each of those decisions. It is highly unlikely that every trucking company 

subject to this regulation will buy the same make and model of APS for each of 

its trucks, and the capital costs will therefore not be uniform or flat for each 

entity. The attempt to analogize this regulation to a flat state tax therefore 

stretches too far. Moreover, the analogy also disregards the fact that staff 

estimated this regulation will result in a net cost savings, even for those truck 

operators installing compliant APSs. Finally, the commenter’s assertion that 

out-of-state operators’ relative cost for an APS will be greater than 

California- based vehicles is mere speculation, without any supporting 

evidence. In fact, it is more likely that California-based sleeper trucks operate 

outside the State more frequently than non-California based sleepers, and that 

their APS costs on a “California activity basis” are therefore higher than the 

APS costs for non-Calfornia based sleepers on a California activity basis. 

This comment also disregards the fact that this regulation is enacted by 

California under its police power to protect the health and welfare of its citizens. 

As demonstrated below in the Agency Reply to Comment 76, this regulation will 

likely be found by a court to be a facially neutral regulation that does not unduly 

burden interstate commerce, and will therefore be upheld against a federal 

Commerce Clause challenge. Also, to the extent this comment maintains this 

regulation violates the Commerce Clause because it discriminates in effect 

against interstate commerce (by imposing disproportionate costs on interstate 

commerce compared to intrastate commerce), courts will likely reject this 

contention and instead find this regulation imposes burdens on interstate 

commerce equivalent to those imposed on intrastate commerce, and therefore 

uphold it against the Commerce Clause challenge (see Agency Response to 

Comment 76). 

Finally, to the extent this comment alleges this facially neutral regulation 

discriminates in effect against interstate commerce (and would therefore be 

subject to review by a court under a strict scrutiny standard of review), several 

courts appear to follow a two step analysis in which only facially discriminatory 

laws are subjected to a strict scrutiny standard of review, and evenhanded laws 

are evaluated under a balancing test described below in the Agency Response 

to Comment 76. National Elec. Mfrs. Ass’n v. Sorrell (2001) 272 F.3d 104, 

National Solid Waste Management Ass’n v. Pine Belt Regional Solid Waste 

Management Authority (2004) 389 F.3d 491. 

76. Comment: If a state law is not found to discriminate against interstate 

commerce, a court will utilize a balancing test enunciated in Pike v. Bruce 

Church (1970) 397 U.S. 137, 142 to determine whether a nondiscriminatory 
- 65 - 

state regulation violates the federal Commerce Clause. The Pike test weighs 

the local benefits of a state regulation against the burdens it imposes on 

interstate commerce. 

The ATCM portion of the regulation violates the Pike test because it imposes 

excessive costs on interstate sleeper trucks that have very infrequent and 

limited operations in California, compared to other sleeper trucks. For this 

category of interstate sleeper trucks, California would obtain minimal benefits 

and yet the trucks would incur exorbitant costs. “For example, for a truck that 

operates only a few hours per year in the State, the per-pound cost of emission 

reduction would be astronomical for that truck. This type of per-activity analysis 

in tax cases is consistent with well-accepted apportionment requirements.” 

(ATA)

Agency Response: As noted by the comment, if a court determines that a 

state law does not discriminate against interstate commerce or directly 

regulates commerce outside of the state’s boundaries, it then balances the 

law’s local benefits against its burdens on interstate commerce to determine if 

the law violates the federal Commerce Clause. Pike v. Bruce Church 397 U.S. 

137, 142. Under this test the state law will be upheld unless it imposes a 

burden on interstate commerce that is clearly excessive in relation to the 

putative local benefits. “If a legitimate local purpose is found, then the question 

becomes one of degree. And the extent of the burden that will be tolerated will 

of course depend on the nature of the local interest involved, and on whether it 

could be promoted as well with a lesser impact on interstate activities.” Ibid. 

Furthermore, courts will accord a greater presumption of validity to a state’s 

laws in the field of safety. Pike 397 U.S. 137, 143, Bibb v. Navajo Freight 

Lines, Inc. (1959) 359 U.S. 520. 

Courts recognize that preventing air pollution is and has been a traditional local 

safety concern. Huron Portland Cement Co. v. Detroit (1960) 362 U.S. 440, 

445-446. This recognition is also expressed in the federal Clean Air Act section 

101(a)(3), where the U.S. Congress declared that states and local governments 

are primarily responsible for preventing air pollution, and in California Health 

and Safety Code sections 39000 and 39001, where the California legislature 

declared a strong public interest in controlling air pollution to protect the “health, 

safety, welfare, and sense of well-being” of Californians. In regards to the 

ATCM portion of the idling regulation, the California legislature declared in 

California Health and Safety Code section 39650 that toxic air contaminants 

can endanger the public health, safety, and welfare, and should therefore be 

controlled to prevent harm to the public health. Pursuant to this directive the 

ARB identified diesel exhaust particulate matter as a toxic air contaminant in 

August 1998, and approved a comprehensive Diesel Risk Reduction Plan in 

September 2000 to significantly reduce emissions from new and in-use diesel 

fueled engines and vehicles. Idling emissions from diesel-fueled heavy-duty 

motor vehicles are identified as sources of diesel exhaust particulate matter in 

the Diesel Risk Reduction Plan and this regulation is therefore an important 
- 66 - 

component of ARB’s plan to reduce emissions of an identified toxic air 

contaminant. These considerations establish that the ATCM portion of this 

regulation serves the legitimate public purpose of protecting the health and 

welfare of California’s residents, which purpose “clearly falls within the exercise 

of even the most traditional concept of what is compendiously known as the 

police power.” Huron Portland Cement Co. (1960) 362 U.S. 440, 442. 

If a court determines that the justifications for a state safety based regulation 

are not illusory, as it would likely find in this case, it will accord the regulation 

significant deference. Raymond Motor Transportation v. Rice (1978) 434 U.S. 

429, 449 (Blackmun, J., concurrence). The court will then assess the 

regulation’s burden on interstate commerce. As set forth at length in the staff 

report, the ATCM portion of the idling regulation requires all diesel-fueled 

commercial motor vehicles to limit idling of the primary diesel engine to five 

minutes at any location. Trucks that utilize APSs complying with specified 

emissions limits are exempted from the five minute idling limit, as are trucks 

electing to use other technologies such as on-shore electrical power or 

technologies producing minimal or no emissions. These requirements apply to 

both California-based and non-California based trucks that operate in the State. 

The regulation therefore does not unduly burden interstate commerce, because 

all truck operators can comply merely by manually shutting off their truck 

engines. This compliance option does not require any additional equipment or 

incur any additional costs, other than those associated with carriers having to 

notify their truck operators of the idling limits. Those trucking companies that 

elect to install a compliant APS are estimated to incur a one time cost of no 

more than $10,500, but that cost will be significantly offset by the savings 

resulting from the reduced fuel consumption and maintenance requirements. In 

fact, staff estimates a payback period of 2.1 years for an APS plus particulate 

matter trap, and also anticipates a net cost savings over the useful life of the 

truck. See section VII, staff report. Furthermore, installing a compliant APS is 

only one of a range of options available to truck operators. These 

considerations demonstrate that this regulation does not impose a burden on 

interstate commerce that clearly exceeds its benefits of protecting the health 

and welfare of California’s residents from exposures to an identified toxic air 

contaminant, and would therefore likely not be found to unconstitutionally 

burden interstate commerce under the Pike balancing test. 

This conclusion also necessarily follows because a state law violates the Pike 

balancing test only if it imposes a burden on interstate commerce that is 

“qualitatively or quantitatively different from that imposed on intrastate 

commerce.” National Elec. Mfrs. Ass’n v. Sorrell (2001) 272 F.3d 104, 109, 

National Solid Waste Management Ass’n v. Pine Belt Regional Solid Waste 

Management Authority (2004) 389 F.3d 491, 502. As discussed above, the

ATCM portion of the regulation requires that both California-based and nonCalifornia based trucks operating in the State idle no longer than five minutes at 

any location, which applies equally to interstate and intrastate trucks. The 
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comment attempts to create a distinction in regulatory burdens by stating that 

interstate sleeper trucks “that have very infrequent and limited operations in 

California” will have to pay “equivalent compliance costs” to an unnamed 

comparison category (which we necessarily assume are California-based 

sleeper trucks, as the existing in-use ATCM already regulates all non-sleeper 

trucks; see section IX.A of the staff report), while providing minimal emission 

benefits (which we also assume are in comparison to California-based sleeper 

trucks). This argument errs in two respects. First, it disregards staff’s 

estimates that in the year 2010 and 2020, emissions from out-of-state 

registered sleeper trucks exceed those from California registered sleeper 

trucks. See section IX.A of the staff report and specifically tables 6 and 7. 

Second, its attempt to again analogize the regulation to the imposition of a state 

tax is inappropriate as explained in the Agency Response to Comment 75a. 

Finally, the ATCM portion of the regulation likely imposes higher regulatory 

burdens on California based sleeper trucks than on out-of-state registered 

sleeper trucks, since the California based trucks will likely be operated in 

California only a fraction of the time compared to their out-of-state counterparts. 

Accordingly, because the regulation does not impose a larger burden on 

interstate commerce than it does on interstate commerce, it will not violate the 

Pike balancing test. 

76a. Comment: Trucking companies cannot limit specific routes to specific trucks 

and only allot routes to those specific trucks that are equipped to operate in 

California. Because out-of-state trucks outnumber California-based trucks by a 

3-1 margin, any emission benefits from regulating out-of-state trucks are 

outweighed by the $9.2 billion financial burden the regulation imposes on outof-state trucks. [Calculated by estimating an average cost of $7500 per APS 

times 1.23 million out-of-state based trucks]. The ATCM portion of the 

regulation therefore “imposes a significant cost on interstate carriers and 

dictate[s] equipment purchases” outside of California, which regulates interstate 

commerce in violation of the federal Commerce Clause. (CTA)

Agency Response: The Agency Response to comment 76 is incorporated

herein. The ARB does not believe that the ATCM portion of the rulemaking will 

impose a significant financial burden on out-of-state trucking fleets. The 

comment presumes that every out-of-state truck in the nation’s fleet must install 

a compliant APS because it may have to drive into California sometime in the 

future. This assumption disregards the fact that trucking fleets utilize advanced 

technologies, such as global positioning systems, to track the locations of 

individual trucks on a real-time basis. Trucking fleets are therefore aware of the 

location of each of their vehicles, and can easily direct only compliant trucks 

into California. Furthermore, many trucks may never enter California because 

of its geographic location. 

77. Comment: State regulations that directly regulate interstate commerce or that 

impermissibly regulate activity occurring wholly outside of the regulating state 

violates the federal Commerce Clause. Healy v. Beer Institute, 491 U.S. 324, 
- 68 - 

332 (1989), Brown-Forman Distillers Corporation v. New York State Liquor 

Authority (1986) 476 U.S. 573, Southern Pacific Co. v. Arizona 325 U.S. 761 

(1945). The portion of the idling regulation that requires new 2008 and 

subsequent heavy-duty diesel trucks certified for sale in California to be 

equipped with a shutdown timer violates the Commerce Clause because it 

effectively controls truck operations beyond California’s borders. This 

requirement prohibits sleeper trucks sold in California from operating the main 

engine for cab comfort even though other states allow such operation to comply 

with Federal Hours-of-Service requirements. “In this instance, a state 

regulation mandating unique equipment effectively mandates its use in other 

states as well.” (ATA)

77a. Comment: The ATCM portion of the regulation “dictate[s] equipment 

purchases” outside of California, in violation of the federal Commerce Clause.

(CTA)

Agency Response to Comments 77 and 77a: If a court finds that Congress 

has not exempted a state law from Commerce Clause scrutiny, it then 

determines whether the law discriminates against interstate commerce or 

directly regulates commerce outside of the state’s boundaries. Such laws are 

virtually per se invalid. Brown-Forman Distillers Corp. v. New York State Liquor 

Authority (1986) 476 U.S. 573, 579. In Brown-Forman Distillers Corporation v. 

New York State Liquor Authority (1986) 476 U.S. 573, and in Healy v. Beer 

Institute (1989) 491 U.S. 324, the U.S. Supreme Court found that two price 

affirmation statutes (for liquor and beer, respectively) violated the Commerce 

Clause because they effectively regulated out-of-state commerce by controlling 

the prices and marketing practices in other states. For instance, the challenged 

New York statute in Brown-Forman effectively forced sellers to forego 

promotional allowances in other states (in which the allowances were legal) or 

would force other states to alter their own regulatory schemes to allow the 

sellers to lower their New York prices. 

In Southern Pac. Co. v. Sullivan (1945) 325 U.S. 761, the Supreme Court held 

that an Arizona law limiting the number of railroad cars in trains within the State 

violated the Commerce Clause. The Court determined that the law was 

ineffective as a safety measure because the record indicated the law increased

the number of train-related accidents. Southern Pac. Co. (1945) 325 U.S. 761, 

775-779. The Court also found that the law substantially impeded interstate 

commerce because its practical effect was to regulate train operations beyond 

Arizona’s borders (by requiring trains to break up or reassemble railroad cars 

before entering and after leaving the State). The Court was especially 

concerned that if Arizona could regulate train lengths, so could other states, 

which would seriously impede interstate commerce. Id. at 775. 

The reasoning cited in the above mentioned cases is inapposite to the new 

engine shutdown timer and the ATCM portion of the rulemaking. First, as 

explained in the Agency Response to comment 75, Congress has likely 
- 69 - 

exempted these requirements from Commerce Clause scrutiny by its 

enactment of the federal CAA provisions allowing only California to adopt and 

enforce new vehicle emission standards in § 209(b) and in-use requirements 

for nonroad sources in § 209(e)(2)(A). 

 

Second, ARB disagrees that the reasoning in the Brown-Forman, Healy, and 

Southern Pac. Co. cases supports a finding that either the new engine

shutdown timer requirement or the ATCM portion of the rulemaking directly 

regulates commerce occurring entirely beyond California’s borders. Unlike the 

price affirmation statutes in Brown-Foreman and Healy, the idling shutdown 

timer requirement does not have a practical effect of regulating commercial 

activity beyond California’s borders, since it only applies to new 2008 and 

subsequent model heavy-duty diesel engines certified for sale and use in 

California. Therefore, businesses such as trucking fleets that do not register 

their trucks in California need not purchase California certified engines 

equipped with the idling shutdown timers. Furthermore, at this time the U.S. 

EPA has not expressed an interest in adopting new engine idle shut down timer 

requirements. However, if and when it does, ARB will work closely with U.S. 

EPA to harmonize the requirements to the greatest extent possible. Also, 

because the federal Clean Air Act preempts all states except California from 

adopting and enforcing in-use requirements for nonroad sources (unless other 

states elect to adopt regulations that are identical to those adopted by 

California), the idling requirements avoid the possibility that other states might 

adopt possibly inconsistent requirements, which concerned the Southern Pac. 

Co. court. 

Both the new engine shutdown timer and the ATCM requirement are analogous 

to the statute at issue in National Elec. Mfrs. Ass’n v. Sorrell (2001) 272 F.3d 

104. In that case, Vermont law required manufacturers of mercury-containing 

lamps to label them in order to inform consumers that the lamps contain 

mercury and should be disposed of in an appropriate manner. 272 F.3d 104, 

107. Lamp manufacturers argued that because of their manufacturing and 

distribution systems, the law violated the Commerce Clause because it would, 

in practical effect, require them to also label lamps sold in every other state. 

The Court of Appeals for the Second District disagreed, and upheld the law, 

reasoning that the statute was indifferent to whether lamps sold elsewhere 

were labeled or not. “To the extent the statute may be said to ‘require’ labels 

on lamps sold outside Vermont, then, it is only because the manufacturers are 

unwilling to modify their production and distribution systems to differentiate 

between Vermont-bound and non-Vermont-bound lamps.” Id. at 110. In this 

case, each of the idling requirements is also indifferent to whether engines sold 

outside of California are equipped with the shutdown timer devices, or if trucks 

outside of California are equipped with an APS. Therefore, under the 

reasoning of the Elec. Mfrs. Ass’n case, these requirements do not violate the 

Commerce Clause. 
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The comment that the new engine shutdown timer requirement prohibits 

sleeper trucks in California from operating the main engine for cab comfort in 

order to comply with the federal Hours of Service regulations is addressed in 

the Agency Response to Comments 73 and 74.