California Air Resource Board (CARB) Regulations

In 2008, CARB imposed two new regulations to reduce greenhouse gas emissions (GHG) from an estimated one million heavy-duty trucks that operate in California. One was created to improve the fuel efficiency of heavy-duty tractors that pull 53-foot or longer box-type trailers. In the attempt to improve fuel efficiency, CARB mandated the installation of “SmartWay” verified aerodynamic technology and the use of low rolling resistance tires. This regulation was called the Heavy Duty (Tractor Trailer) Vehicle Greenhouse Gas Reduction Regulation.

The regulation was projected to reduce GHG emissions by 1 million metric tons of carbon dioxide- equivalents statewide by 2020. The regulation was also anticipated to save the trucking industry $8.6 billion in fuel savings, and reduce consumption by 5 billion gallons across the country and 750 million gallons in California.

The second regulation was the Statewide Truck and Bus rule that required truck owners to install diesel exhaust filters on their rigs, the rule was designed so nearly all vehicles would be upgraded by 2014. Truck owners were asked to replace engines older than 2010 model year according to a staggered implementation schedule that extends from 2012 to 2020. This regulation was estimated to reduce diesel emissions 68 percent by 2014 and NOx by 25 percent. The regulation is expected to save 9,400 lives between 2011 and 2025, and greatly reduce health care costs. The benefits have an estimated value of $48 billion to $69 billion.

In addition, CARB adopted an Airborne Toxic Control Measure (ATCM) for transport refrigeration units (TRUs) and TRU generator sets in 2004. The regulation was also designed to reduce emissions of diesel particulate matter (PM) from diesel-powered engines used to refrigerate perishable goods in insulated truck and trailer vans, rail cars, and domestic shipping containers. The rule was amended in 2010, and again in 2011.

Read further for more information on how the CARB regulations affect your business.

Training Classes

Truck and Bus Regulation

On-Road Heavy-Duty Diesel Vehicle (In-Use) Regulation

The proposed regulation began in 2010, and required the installation of verified particulate matter (PM) diesel emission control strategy (DECS) on heavy-duty vehicles depending on their model year. By 2012, fleets would need to start replacing their vehicles with trucks that met the new 2010 emission standards. By 2015, most older model diesel engines would either have a DECS installed, or an engine that has a diesel particulate filter (DPF). Tucks with 1995 MY and older engines must be replaced starting in 2015.

The regulation established PM and NOx emission requirements for vehicles subject to the regulation. Affected vehicles include on-road and off-road heavy-duty diesel fueled vehicles with a GVW greater than 14,000 pounds, and diesel fueled shuttle vehicles of any weight that carry a capacity of 10 or more passengers and drive an average of 10 trips per day between various terminals and stations. The regulation did not apply to military tactical support vehicles, authorized emergency vehicles, and private motor homes not used for commercial purposes. Other vehicles that did not apply are:

  • Solid waste collection vehicle
  • Municipality and utility owned vehicles
  • Urban buses
  • Transit fleet vehicles
  • Mobile cargo handling equipment at ports and intermodal rail yards
  • Certain Off-road vehicles
  • Dedicated snow-removal vehicles
  • Two-engine cranes
  • Historic vehicles

Lighter trucks and buses with a GVW of 14,001 to 26,000 lbs do not have meet compliance requirements until 2015
In each year, fleet owners will be provided with two options to comply with new diesel engine requirements.

  1. BACT Compliance Schedule: For the first option, to abide by the proposed NOx and PM performance requirements, a fleet owner must comply with the prescribed best available control technology (BACT) schedule. A fleet must install PM retrofits and replace vehicles, or engines, according to a prescribed schedule based on the existing engine model year

Best Available Control Technology Compliance Schedule

Engine Model-Years

BACT Requirements Date by

Compliance Date 2010 Engine by



January 1, 2015



January 1, 2016


January 1, 2012

January 1, 2020


January 1, 2013

January 1, 2021


January 1, 2014

January 1, 2022

2007 or newer

January 1, 2014 if not OEM equipped

January 1, 2023

  1. Phase-In Option: The second option to comply is to meet a BACT percent limit. This option indicates the minimum number of engines each year that, as a percentage of all the vehicles in the fleet, must have the have the highest-level DECS installed and have the BACT requirement for NOx to be compliant. Engines in the fleet that were originally equipped with a DPF by the manufacturer would count towards the number of verified DECS installed. The BACT percent limits is best suited for fleets that prefer to buy engines with 2010 emissions technology

Compliance Deadline as of January 1st

Percent of Total Fleet Complying with PM BACT Requirements












All vehicles must comply with requirements of section 2025(g)

For small fleets with one to three vehicles, they would be exempt until January 1, 2014. However, by 2014 small fleets have to show they have cleaned at least one vehicle to a lesser requirement. That vehicle would not need to meet the 2010 engine requirement until 2020. Small fleets can meet the PM DECS requirements by either installing the highest level PM filter retrofits that have been verified by California Air Resource Board (CARB) or with PM filters that are standard equipment on 2007 or newer engines. To use the small fleet option, heavy-duty vehicles must comply with the following schedule:

  • One vehicle must have a PM filter by January 1, 2014
  • Two vehicles must have PM filters by January 1, 2015
  • Three vehicles must have PM filters by January 1, 2016

A single truck owner can delay the PM DECS requirement until January 1, 2014 and will be able to delay the truck replacement until 2023.

For more information on the Truck and Bus Regulation, please visit CARB’s website here.

Tractor-Trailer Greenhouse Gas (GHG) Regulation

The purpose of the regulation is to reduce GHG emissions from heavy-duty trucks and 53-foot box-type semitrailers that transport freight on a highway within California. This regulation includes dry-van, refrigerated van trailers, and the heavy-duty tractors that pull them. In order to reduce emissions vehicles subject to the regulation will be required to use low-rolling resistance tires and meet SmartWay certified aerodynamic equipment requirements.

Company owners of tractors subject to the regulation must either purchase new SmartWay verified tractors or retrofit existing tractors with low rolling resistance tires. Owners of trailers must either purchase new SmartWay certified trailers or retrofit existing trailers with SmartWay verified aerodynamic technologies and low rolling resistant tires.

Tractor Requirements (revised April 12, 2012)

Affected Tractors*


Compliance Date

2011 MY and newer HD sleeper cab tractors SmartWay Certified (no retrofit available) January 1, 2010
2011 MY and newer HD day cab tractors LRR tires only January 1, 2010
All 2010 or older MY HD tractors (including sleeper and day cabs) LRR tires only January 1, 2013

Trailer Requirements (revised April 12, 2012)

Affected Tractors*


Compliance Date

2011 MY and newer dry vans SmartWay Certified or retrofitted with LRR tires + 5% fuel saving aerodynamic technologies January 1, 2010
2011 MY and newer refrigerated vans SmartWay Certified or retrofitted with LRR tires + 4% fuel saving aerodynamic technologies January 1, 2010
2010 or older MY box-type trailers SmartWay Certified or retrofitted with 5%/4% fuel saving aerodynamic technologies January 1, 2013
SmartWay verified LRR tires January 1, 2017
2003-2004 MY refrigerated van trailers SmartWay Certified or retrofitted with LRR tires + 4% fuel saving aerodynamic technologies January 1, 2018
2005-2006 MY refrigerated van trailers SmartWay Certified or retrofitted with LRR tires + 4% fuel saving aerodynamic technologies January 1, 2019
2007-2009 MY refrigerated van trailers SmartWay Certified or retrofitted with LRR tires + 4% fuel saving aerodynamic technologies January 1, 2020

*Applies to 53-foot or longer box-type trailers in CA MY – model year LRR – low rolling resistance

Small and large fleets can take advantage of special compliance opportunities for their pre-2011 model year trailers. While all 2011 and newer model year trailers must comply as of January 1, 2010, small and large fleets can choose to phase-in compliance of their 2010 and older model year trailers with the aerodynamic technology requirements of the regulation as showing in the table below.

Small fleets are defined as a fleet with 20 or fewer tractor-trailers. In order for small fleets to participate in the compliance schedule below, they had to put forward a Small Fleet Compliance Plan by September 1, 2012.

Large fleets have two options for compliance, and each requires a particular percentage of trailers brought into compliance every year. In order for a large fleet to participate in Option 1, they must have registered with California Air Resource Board (CARB) by July 1, 2010, while fleets participating in Option 2 had to register by June 1, 2012. The low rolling resistance tire requirements for 2010 and older model year trailers are not included in the compliance schedules, and the tire standards for these trailers must be met by January 1, 2017.

Large Fleet Compliance Schedule

Must Comply Before January 1 of:







% of Fleet that must comply

Option 1







Option 2






Small Fleet Compliance Schedule

Must Comply Before January 1 of:





% of Fleet that must comply





For further information on the Heavy-Duty (Tractor-Trailer) Greenhouse Gas Regulation, please visit CARB’s website here.

The California Air Resources Board has posted a new fact sheet with information about the storage trailer exemption requirements of the Tractor Trailer Greenhouse Gas (GHG) regulation. The fact sheet can be found at the following.

Transport Refrigeration Unit (Reefer) ATCM Regulation

The California Air Resources Board (CARB) staff proposed amendments to the transport refrigeration unit (TRU) Airborne Toxic Control Measure (ATCM) that CARB adopted on February 26, 2004 and last amended in 2010. The regulation was designed to reduce emissions of diesel particulate matter (PM) from diesel-powered engines used to refrigerate perishable goods in insulated truck and trailer vans, rail cars, and domestic shipping containers. The regulation also applies to TRU generator sets (gen sets), which provide onboard electric power to electrically driven refrigeration systems that are used in shipping containers and trailers.

The current regulation requires in-use TRUs to reduce PM emission levels by 85 percent, and to be in accordance with a compliance schedule based on a seven-year operational life for the equipment. The proposed amendments were made in order to improve compliance rates and enforceability; restore competitive fairness to those businesses that elected to comply with the regulation during 2008 through 2010 while other businesses opted to defer their compliance efforts in light of the U.S. EPA’s delay in issuing CARB an authorization to enforce the regulations; and clarify existing requirements. The 2011 amendments would primarily:

  1. Extend the Ultra-Low Emission TRU (ULETRU) in-use performance standard compliance date by one year for MY 2001 through MY 2003. This would also extend the compliance for older TRU engines that met less stringent Low-Emission TRU (LETRU) performance standard by December 31, 2008.

ULETRU Extension and Older TRU Engines that Met LETRU Deadline

Engine MY

Deadline LETRU Met by

ULETRU Deadline



2001 & Older












  1. Clarify the manual record keeping requirements and add automated electronic tracking system requirements
  2. Extend responsibility to ensure California-compliant TRUs are used by brokers, shippers, and distributors
  3. Allow unit manufacture year, instead of engine model year, to determine compliance requirements
  4. Add an exemption for TRUs used by mobile catering companies that feed emergency responders
  5. Require original manufacturers and engine rebuilders to provide supplemental engine emissions labels and registration information documents
  6. Clarify existing requirements and add requirements to improve enforceability

The amendment delayed the ULETRU compliance date, but the increase of the maximum potential cancer risk would be negligible. In the original Staff Report, CARB determined the potential excess cancer risk from diesel PM emissions attributable to TRUs during a 70 year period was 100 in a million.

TRUs are refrigeration systems powered by integral diesel engines. Federal and State regulations have produced stringent emission standards for TRU engine manufacturers. These standards are characterized by emission “tier” levels that apply to a range of manufacturing MYs.

Effectiveness of PM Emission Standards for New TRU Engines (25 to 50 hp)

New Engine Emission Tiers

Percent PM Control (from Tier 0 Baseline)

Tier 0 (1998 and older)


Tier 1 (1999-2003)


Tier 2 (2004-2007)


Tier 4i (2008-2012)


Tier 4f (2013 and subsequent)


Effectiveness of PM Emission Standards for New TRU Engines (Less than 25 hp)

New Engine Emission Tiers

Percent PM Control (from Tier 0 Baseline)

Tier 0 (1999 and older)


Tier 1 (2000-2004)


Tier 2 (2005-2007)


Tier 4f (2008 and subsequent)


In order to reduce PM emissions, CARB verified diesel PM retrofit devices based on levels of PM control. For LETRU, a level 2 verified diesel emission control strategy (VDECS) is required, while a Level 3 VDECS is required for ULETRU. The percent of PM control for these two levels is 50 and 85 percent, respectively.

The original TRU regulation adopted in 2004 was developed to reduce emissions through retrofits, engine repowers, or unit replacements, and established a compliance schedule based on the MY of the TRU engine. Ultimately, all TRUs must have 85 percent PM control to fully comply with the regulation, and only Level 3 retrofits are capable of providing the necessary PM control. MY 2013 trailer TRU engines (25-50 hp) will be certified to final-Tier 4 (Tier 4f) standards with 97 percent PM control and will meet the ULETRU in-use standard. Owners of MY 2004 and newer TRUs must be complaint with ULETRU in-use standards by the end of the seventh year after the engine model year. The four paths to follow compliance are:

  1. Retrofit existing TRU with a Level 3 VDECS at $5,500 capital cost
  2. Replace existing unit (engine and refrigeration system) with a new TRU equipped with Tier 4i engine at $16,000-$22,000. The engine must be upgraded in seven years with a Level 3 retrofit ($5,500) or another new TRU equipped with a Tier 4f
  3. Repower the TRU with a new Tier 4i engine at $5,750-$8,400 (must be upgraded with a Level 3 retrofit or Tier 4f in seven years)
  4. Use alternative technology, like an electric standby-equipped TRU at $700-$3,000. Electric plug infrastructure at the home base facility and all other facilities is required, at significant additional cost, to ensure the TRU engine operation is eliminated at these facilities. The Staff Report in 2003 concluded that the infrastructure upgrades would be cost-prohibitive

CARB conducted workshops in 2010 to consider amendments to the original TRU ATCM. However, the staff recognized more data needed to be collected and analyzed before specific amendments could be recommended. As a result, staff broke the amendment process into two phases. Phase 1 addressed time-critical amendments that required CARB’s approval before the end of 2010, and Phase 2 would address the remaining issues and concerns. The Phase 1 amendments were:

  1. Added an interim, Lower-Cost Retrofit Option for a Subset of TRUs (engines rated at less than 25 hp)
  2. Linked the compliance schedule for TRU flexibility engines to their emissions Tier to reduce operational life of these TRUs, so upgrades were required one or more years sooner
  3. Expanded reporting by TRU manufacturers to help staff validate registration information

Phase 2 began in early 2011, and consisted of the amendments mentioned earlier in the summary. However, the extension on the compliance date for ULETRU and LETRU will affect the emission results. Extending the deadline between MY 2001 and MY 2004 will result in 0.042 tons per day (tpd) of PM emissions increase in 2016, 0.004 tpd in 2017, and 0.012 tpd in 2018. Other emission impacts include:

  • Allowing the use of unit manufacture year instead of engine model year for determining compliance dates will increase 0.150 tpd of diesel PM from 2009 through 2018
  • The combine emission impacts of all the proposed amendments will increase total diesel PM emissions between 2009 and 2018 by 0.21 tpd

CARB Staff evaluated the proposed TRU ATCM 2011 amendments on the economic impact it will have on businesses by estimating the effect of the regulatory costs on small businesses and typical businesses.

Total Estimated Regulatory Costs for the Proposed Amendments (2011 Dollars)

Proposed TRU ATCM 2011 Amendment

Regulatory Cost or (Savings)

ULETRU Extension for MY 2003 and older Timely LETRU Compliance


Electronic Record keeping for Hybrid Electric/Electric Standby

($3.9 million)

Compliance Verification for Responsible Parties

$11 million

Exemption of TRUs Used During Emergencies


Use of TRU Manufacture Year rather than Engine Model Year

($21 million)

Supplemental Labels and Registration Information Document

$1.6 million

Net Total Cost or (Savings)

($13 million)

During the amendment process there were a couple of key issues, such as the availability of Level 3 VDECS to meet the December 31, 2011 ULETRU compliance deadline. According to the Staff report, there should be two addition Level 3 VDECS to make the grand total of 3 available retrofits.

In addition, the operation life extension for MY 2004 and newer TRU engines was another concern. CARB has decided to not extend the current seven-year operational life standard, and Staff has identified issues involved with providing any extension, including:

  • The public health risk at the current seven-year operational life still results in potential cancer risk levels. Extending the operational life could exacerbate the problem. Increasing the operational life 1, 2, or 3 years would increase the cancer risk by 11, 23, and 42 percent, respectively.
  • There are no mitigations to offset the emission increases associated with extending the operational life
  • The VDECS manufactures would be left with no market for one or more years
  • Apparently the refrigerated trucking industry did not feel the effects of the global recession to the same extent as other industry sectors

The overall compliance rate for MY 2003 and older units is about 65 percent. However, the compliance rates for each MY is declining from 80 percent for MY 2001 and older TRUs to about 30 percent for MY 2003 TRUs. CARB believed this was not economically fair for fleets that have invested in compliance technologies, so they created steps to improve compliance rates. These steps included sending notification letters to owners of TRUs that are register in CARB’s Equipment Registration (ARBER) system with noncompliant equipment, and increasing inspections at border crossings.

For more information on the Transport Refrigeration Unit (Reefer) ATCM Regulation, please visit CARB’s website here.