The In-Use Locomotive Regulation will require operators to convert from diesel-powered locomotives and increase the use of zero-emission (ZE) technology to achieve emission reductions.
 

Compliance Requirements

There are three options for complying with this rule: Spending Account, Alternative Compliance Plan (ACP), Alternative Fleet Milestone Option (AFMO). The In-Use Operational Requirements (IUOR) are requirements that apply when choosing the Spending Account compliance option and potentially when choosing the ACP compliance option.
 
Requirements that all operators are required to comply with in addition to the 3 options listed above:

• By July 1, 2026, all Locomotive Operators must register all Locomotives.
• All locomotives with automatic shutoff devices will not be permitted to idle longer than 30 minutes, unless for an exempt reason. Exemptions align with those described by U.S. EPA and will be granted for reasons like maintaining air brake pressure or keeping the driver cabin heated or air conditioned.

In-Use Operational Requirements (IUOR)

The following In-Use Operational Requirements apply for operators that choose the Spending Account compliance option:

• Only locomotives less than 23 years old will be able to be used in California, unless operated in a ZE configuration.
• Switch, industrial, and passenger locomotives with an original engine build date of 2030 and beyond will be required to operate in a ZE configuration in order to operate in California.
• Freight line haul locomotives with an original engine build date of 2035 and beyond will be required to operate in a ZE configuration in order to operate in California.

 
These requirements may also apply to operators that choose the ACP compliance option depending on the ACP application, which is discussed in the ACP paragraph.
 

Spending Account

The Spending Account compliance option is the main compliance option and requires locomotive operators to fund their own trust account based on the emissions created by their locomotive operations in California. The dirtier the locomotive, the more funds must be set aside.
 
Spending Account funds will be used in the following manner:

• Until 2030: to purchase, lease, or rent Tier 4 or cleaner locomotives, or for the remanufacture or repower to Tier 4 or cleaner locomotive(s).
• At any time: to purchase, lease, or rent ZE locomotive(s), ZE capable locomotive(s), ZE rail equipment, or to repower to ZE locomotive(s) or ZE capable locomotive(s).
• At any time: for ZE infrastructure associated with ZE locomotive(s), ZE capable locomotive(s), ZE rail equipment.
• At any time: to pilot or demonstrate ZE locomotives or ZE rail equipment technologies.

Due July 1 every year starting in 2026, operators shall deposit the Spending Account Funding Requirement into their Spending Account:

Spending Account per Locomotive [$]: {(Weighted Factor x PM EF¹) + NO_x EF¹ [g/bhp-hr]} x Annual Factor x Usage [MWh]

1. Locomotive PM & NO_x EFs are based on the certification level as shown in the U.S. EPA Locomotive ECD.

Table 1

Alternative Compliance Plan (ACP)

The ACP compliance option allows locomotive operators to reduce emissions through other strategies, provided those strategies are not already required. ACPs must achieve emission reductions equivalent to or greater than those required under the Regulation. The ACP shall reduce PM, NO_x, and GHG emissions in California in amounts equivalent to or greater than the reductions that would have been achieved via the Spending Plan or the Regulation’s general requirements. The ACP can replace the Spending Account, the IUOR, or both. The operator will have to request which option the ACP replaces, then CARB will review the ACP to ensure it meets the requirements for the requested option(s).
 
An initial ACP application must be submitted at least six months prior to the requested start date of the ACP, and the approved ACP is valid for a Five-Year Verification Period. Annual ACP reports must be submitted to CARB by July 1 of every year during the Five-Year Verification Period.
 

Alternative Fleet Milestone Option (AFMO)

The AFMO compliance option allows operators to comply with the Regulation by meeting specific fleet requirements. The AFMO compliance option is an alternative compliance option to the Spending Account and the IUOR.
 

• Beginning January 1, 2030: 50% of the annual fleet usage in California must be from Tier 4 or cleaner locomotives.
• Beginning January 1, 2035: 100% of the annual fleet usage in California must be from Tier 4 or cleaner locomotives.
• Beginning January 1, 2042: 50% of the annual fleet usage in California must be from ZE locomotives, ZE capable locomotives, or ZE rail equipment.
• Beginning January 1, 2047: 100% of the annual fleet usage in California must be from ZE locomotives, ZE capable locomotives, or ZE rail equipment.

Reporting Requirements

All of the following reports are due annually July 1st, starting 2026:
 

Locomotive Emissions Report

• Locomotive Identifier
• Usage in California during the Reporting Year.
• For AESS equipped Locomotives: the time, date, location, duration, and reason of each instance when a Locomotive idled for longer than 30 minutes in California.

Spending Account and Spending Account Deposit Credit Annual Report

• Locomotive Operator Information
• Calculated Spending Account Funding Requirement Information

In-Use Operational Requirements Report

• The total MWh of Operation since the Locomotive’s Original Engine Build Date when requesting to use a locomotive for longer than 23 years.
• For each ZE Capable Locomotive operated in California during the Reporting Year:
  • Usage in ZE Configuration in California
  • Usage in a non-ZE Configuration in California

Alternative Compliance Plan Report

• Locomotive Operator Information
• Explanation of the progress
• Explanation of how the reductions were Quantifiable, Verifiable, and Enforceable
• Location(s) of the emissions reductions
• Detailed description of all locomotives when using ACPs as alternative compliance to the In-Use Operational Requirements

Alternative Fleet Milestone Option Report

• For each ZE Rail Equipment Operated in California during the Calendar Year:
  • External identifier for ZE Rail Equipment.
  • ZE Rail Equipment serial number.
  • Usage during the immediately preceding Calendar Year.
• Detailed calculations demonstrating the Locomotive Operator’s progress.
• Information about each ZE Locomotive

 
Exemptions and reports for exemptions can be found in the regulation.
 
If your facility is in the South Coast Basin or is within the jurisdiction of South Coast Air Quality Management District (SCAQMD), please see our overview of the SCAQMD Rule 2306 requirements. In addition, please see our article discussing how this Regulation and Rule 2306 differ and overlap.
 
Trinity can assist with reporting and compliance strategies. If you have any questions regarding the rule and maintaining compliance for your facility, please email Tiffany Wang or Trinity’s Irvine office.