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.    

Class I locomotive operators are those earning revenue greater than $900 million annually. California has two Class I locomotive operators: Union Pacific and BNSF Railway Company. Class I locomotive operators operate two basic types of locomotives:

Switch Locomotives, called “Class I switchers” in this fact sheet, are smaller locomotives that pull freight throughout railyards or for short distances outside railyards. They create harmful emissions in the communities where they operate. The Class I locomotive operators operate approximately 500-600 switchers in California.

Line Haul Locomotives, called “line haul locomotives” in this fact sheet, are large locomotives that haul freight over long distances throughout the country. Class I locomotive operators operate approximately 11,000-12,000 unique line haul locomotives annually in California.

Emissions

• Diesel-powered locomotives emit particulate matter (PM2.5) and oxides of nitrogen (NOx) which have been shown to be harmful to human health, causing illness and premature death.
• Class I locomotives create about 95% of all locomotive emissions statewide. The charts below show emissions of PM2.5 and NOx separated by locomotive type.

2022 Statewide PM2.5 Emissions by Locomotive Type

2022 Statewide NOx Emissions by Locomotive Type

Due to insufficient inventory data, historic locomotives are not included in these figures.   

Continued Reliance on Older Locomotives

Through a voluntary agreement, Class I locomotive operators report their South Coast Air Basin data to CARB.[1] The chart below shows continued reliance on older, dirtier Tier 0 and Tier 1 locomotives and very slow uptake of newer, cleaner Tier 4 locomotives.

1998 MOU Data 2010-2020 Aggregated by Engine Tier

Locomotive Emissions Compared to Truck Emissions

Heavy-duty trucks move much of the same freight as locomotives. Below is an example of heavy-duty truck emissions compared with emissions from line haul locomotives moving the same amount of freight under current emission requirements.

Total PM2.5 Emissions in Communities Within 20 Miles of the Ports^1,2

[1] CARB Draft Truck vs. Train Emission Analysis. (weblink: https://ww2.arb.ca.gov/resources/fact-sheets/draft-truck-vs-train-emissions-analysis)

[2]Based on the projected average mix of trucks and trains in California in the given year

• Starting in 2020, heavy-duty trucks will create less PM2.5 than line haul locomotives hauling the same freight.
• Beyond 2023, future CARB regulations such as the Advance Clean Trucks Regulation bring truck emissions to zero (CARB Advanced Clean Trucks Regulation; https://ww2.arb.ca.gov/rulemaking/2019/advancedcleantrucks)

More information on the Truck vs. Train Analysis can be found on the website: DRAFT Truck vs. Train Emissions Analysis | California Air Resources Board

Class I Locomotive Operators and the In-Use Locomotive Regulation

1.  Starting in 2024: 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 will 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.
• Beginning in 2030, all Class I switch 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.
• Beginning in 2035,  all Class I line haul locomotives with an original engine build date of 2035 and beyond 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.  Starting in 2024: Idling Limit

• 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.

4.  Starting in 2024: 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.

Class I Locomotive Emission Reductions under the In-Use Locomotive Regulation

Under the Regulation, Class I locomotive PM2.5 emissions including both Class I switchers and line haul locomotive emissions, are projected to decrease by over 90% compared with the baseline scenario. NOx emissions from Class I locomotive operators are projected to decrease by over 86%.

Statewide PM2.5 Emissions from Class I Locomotives

Historic locomotives are not included in this PM2.5 graphic due to insufficient population data.

Statewide NOx Emissions from Class I Locomotives

Historic locomotives are not included in this NOx graphic due to insufficient population data.