California Air Resources Board

Locomotives are self-propelled, rail-mounted off road equipment used to push or pull trains.  The combination of locomotive(s) pulling freight or passenger railcars forms a train.  Higher horsepower line haul locomotives and lower horse power switcher locomotives operate in California.  A typical freight and passenger locomotive in the United States is powered by a diesel engine that drives an electrical generator or alternator.  Other sources of NOx and PM2.5 emissions in railyards include railcar movers, yard trucks, drayage trucks, and other types of cargo handling equipment.  Locomotives and railyards are a source of harmful NOx emissions, PM 2.5 emissions, and GHG emissions, the California Air Resources Board (CARB) has developed and implemented a number of measures to understand and reduce locomotive and railyard emissions, including studies, regulations, enforceable agreements, and funding of clean technology.