California Air Resources Board

The In-Use Locomotive Regulation (Regulation) will achieve emission reductions from diesel-powered locomotives and increase the use of zero-emission (ZE) technology. The Regulation will help meet California’s public health, air quality and climate goals by reducing criteria pollutants, toxic air contaminants, and greenhouse gas emissions for locomotives in-use. 

• Passenger locomotives propel passenger cars and use head-end power for functions such as heating, lighting, and air conditioning. Head-end power may be supplied by the primary engine or a separate diesel generator.
• Travel routes for these locomotives range from short, local commuter distances to long, cross-country trips.
• Passenger locomotive operators in California include: Metrolink, Caltrain, Amtrak Pacific Surfliner, Capital and San Joaquin Valley Corridors, Altamont Commuter Express, and the North Coast Transit District. 

2022 Passenger Locomotive Population Breakdown by Tier

¹Some passenger locomotive operators use ZE multiple units which do not use an onboard power source, because of this, multiple units do not meet the definition of “locomotive” in the Regulation, therefore they are excluded from the inventory of applicable locomotives under the Regulation.

Passenger Locomotives and the In-Use Locomotive Regulation

1.  Spending Account

• Locomotive operators will be required 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 must be used to purchase the cleanest locomotives or upgrade existing locomotives to the cleanest tier.

2.  Starting in 2030: In-Use Operational Requirements

• Only locomotives less than 23 years old will be able to be used in California, unless operated in a ZE configuration.
• Beginning in 2030, all passenger locomotives with an original engine build date of 2030 or newer will be required to operate in a ZE configuration—i.e., qualify as either a ZE locomotive or ZE capable locomotive to operate in California.

3.  Idling Limit

• All locomotives with automatic shutoff devices will not be permitted to idle longer than 30 minutes, unless for an exempt reason. Exemptions will 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.

4.  Registration and Reporting

• Locomotives operating in the state will be required to register with CARB.
• Locomotive activity, emission levels and idling data must be reported annually.

5.  Flexibility in the In-Use Locomotive Regulation for Passenger Locomotive Operators

• From collaborative discussions with passenger locomotive operators, CARB staff has developed alternative pathways to comply, including the Alternative Compliance Plan and the Alternative Fleet Milestone Option.
• Flexibilities allow passenger operators more pathways to carry out their longer term ZE plans and to support their goals of strengthening transportation equity by working to increase ridership.
• The Alternative Compliance Plan (ACP): As an alternative to the Spending Account, the In-Use Operational Requirements, or both, this option will allow locomotive operators to achieve equivalent emission reductions within the constraints that often govern passenger locomotive operations.
  • Under an approved ACP, locomotive operators will be able to use a wide variety of emission reduction strategies, provided the emission reductions are not already required, and they meet the timing, quantity, and location requirements described in the Regulation.
  • To allow passenger operators flexibility to operate within the limitations of their various funding sources, the implementation period may be up to five years. A periodic re-evaluation will allow updates as funding circumstances change and new technologies become available.
• The Alternative Fleet Milestone Option (AFMO): As an alternative to the Spending Account and the In-Use Operational Requirements, this option will allow locomotive operators to reduce emissions by committing to four operational milestones, and to offset the use of older locomotives that would have been banned under the main regulatory pathway:
  • Beginning January 1, 2030, 50 percent of annual fleet usage in California must be from Tier 4 or cleaner locomotives.
  • Beginning January 1, 2035, 100 percent of annual fleet usage in California must be from Tier 4 or cleaner locomotives.
  • Beginning January 1, 2042, 50 percent of annual fleet usage in California must be from ZE locomotives, ZE capable locomotives, or ZE rail equipment.
  • Beginning January 1, 2047, 100 percent of annual fleet usage in California must be from ZE locomotives, ZE capable locomotives, or ZE rail equipment.
  • Alternative Fleet Milestone Offsets: Prior to January 1, 2047, operation of ZE locomotives or ZE rail equipment in California could offset operation of a locomotive operator’s pre‑Tier 4 Locomotives.

Visit the webpage Reducing Rail Emissions in California | California Air Resources Board to learn more about how the Regulation will apply to all locomotive operators, including passenger locomotive operators.

Passenger Locomotive Emissions Under the Regulation

Diesel-powered passenger locomotives create emission of particulate matter (PM2.5) and oxides of nitrogen (NOx) which have been shown to be harmful to human health, causing illness and premature death.

Under the Regulation passenger locomotive PM emissions are projected to drop by approximately 44 percent and NOx emissions are projected to drop by approximately 41 percent compared with the baseline scenario.

The graphic below shows the impact of passenger locomotive operator compliance with the Regulation in terms of cars permanently removed from California roads.

PM2.5 Reduction from Passenger Locomotive Operator Compliance with the Regulation

Passenger Operations and Locomotive Technology

• Compared to other California locomotive operators, passenger locomotive operators have embraced cleaner locomotive technology at the highest rate.
• Passenger locomotive duties, which are confined to set routes with regular station stops, are suited to existing ZE operations. Passenger locomotive operators could also provide critical support for emerging ZE technologies through pilots and demonstrations.
• By using individually powered passenger cars called multiple units, some passenger locomotive operators are already using ZE technology.
• Passenger locomotives can plug into the power grid using wayside power if the locomotive and the station are equipped, removing the need to use diesel “head-end power” engines; this will allow a passenger train to run things like air conditioning and lighting with zero emissions.

Incentive Funding

CARB offers grant funding to operators seeking assistance to upgrade or replace their locomotives to Tier 4 or zero emission. Visit the CARB Incentives for Locomotives webpage for more information: CARB Incentives for Locomotives | California Air Resources Board