Policy update

California’s in-use locomotive regulation

California’s latest effort to support clean air and reduce greenhouse gas emissions targets how much pollution railroads may emit and what kinds of engines rail companies may use while operating in the state. The In-use Locomotive Regulation, approved by the California Air Resources Board in late April 2023, will force the retirement of old diesel locomotives and speed the transition to zero-emission technology. The U.S. Environmental Protection Agency must approve the regulation before it can be implemented.

This paper first reviews the current locomotive fleet in California and earlier efforts to reduce train pollution in the Greater Los Angeles metropolitan area. It then highlights key provisions and milestones in the new regulation. Starting in 2030, locomotives must be less than 23 years old to operate in California. Switch, industrial, and passenger locomotives built after 2030 and line-haul locomotives built after 2035 must operate with zero-emission in the state. Rail companies must also set up spending accounts based on how much pollution their locomotives emit in the state; the companies will then use those funds to finance their own fleet upgrade to zero-emission. A locomotive operator can adopt alternative compliance plans provided in the regulation with CARB’s approval.

The regulation is expected to reduce 7,400 tons of particulate matter, 386,300 tons of nitrogen oxides, and 21.6 million tons of greenhouse gas emissions cumulatively between 2023 and 2050.