California Air Resources Board

• Class II locomotive operators pull freight over short and medium distances, generally between a small number of states.
  • Class II operators are defined by earning revenue between $47.3 million and $1.05 billion. [1]
• Class III locomotive operators pull freight over short distances, generally between a port and railyard or between a railyard and an industrial client.
  • Class III operators are defined by earning revenue less than $47.3 million. [1]
• Typically, industrial locomotive operators use locomotives to move freight out to a main track so that it can be connected to a larger train.

• Class III and industrial locomotive operators generally use switch locomotives or “switchers”.
  • Switchers are powered by engines with 2,300 horsepower or less.
• As of 2022, Class III and industrial locomotives are mostly Pre‑Tier 0. These are the oldest and highest‑polluting type of locomotive.

Class II and III Locomotive Population by Tier (2022)*

*Currently there is a single Tier II locomotive operator working in California, CARB staff have not found sufficient data to characterize this population, therefore it is not included here.

Industrial Locomotive Population Breakdown by Tier (2022)

PM2.5 From One Tier 0+ Switch Locomotive^[2]

Class II, Class III, and Industrial Operations and Locomotive Technology

• Class II, Class III and industrial operations are ideal for battery‑electric locomotive operation with today’s technology.
  • These operations usually occur within a smaller area and remain close to charging infrastructure.
  • Class II, III and industrial operators could provide critical pilot and demonstration opportunities for ZE technology.
• ZE switchers are already commercially available in limited quantities for Class III and industrial operators. and ZE switcher availability will increase by 2030.

Historic Locomotives

• Historic locomotives may be kept in their original configuration to help interpret history and serve educational purposes transporting passengers.
• Approximately 23 diesel‑powered historic locomotives operate in California.
• Emissions from historic locomotives are not fully documented. Emissions from historic locomotives are therefore not included in CARB’s locomotive emissions inventory.

Incentive Funding

CARB offers funding assistance to operators interested in Tier 4 or ZE locomotives. This includes remanufacturing and new purchases. Visit the CARB incentives webpage for more information.

[1] The Surface Transportation Board defines locomotive operator classes, accounting for inflation. (Surface Transportation Board Economic Data: https://www.stb.gov/reports-data/economic-data/)

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