Skip to main content

Train Technology

Clean, Green Trains

Regional Rail and BART run on different types of tracks and use different types of train cars. Regional Rail tracks are 4 feet, 8.5 inches wide and trains are driven by a locomotive. BART tracks are 5 feet, 6 inches wide, with an electrified “third rail” that powers the trains. There are also many structural, vehicle weight, and regulatory differences between the two systems.

All Regional Rail systems within the Northern California Megaregion currently use diesel-powered engines. However, passenger rail in California will be converting to zero-emission trains in the next 15 years. These modern, environmentally-friendly vehicles will reduce greenhouse gas emissions and help pave the way for a new frontier of public transportation. Their ability to stop and start faster without increasing travel time will provide opportunities to build more stations closer together and help create a convenient intercity system, much like BART.

train ilustration with wind and hand holding plant

Caltrain will be the first Northern California passenger rail service on the national rail system to convert to electric operation. As part of the Caltrain Modernization Program, modern, electric, double-deck, multiple-unit trains will be in service by 2024.

The current BART fleet is already electric, except for the BART-to-Antioch trains, which are fueled by renewable diesel, an advanced biofuel produced from bio-based sources such as vegetable oil. Since 2018, BART has been leading an initiative to support a sustainable, connected Bay Area by introducing its Fleet of the Future: lightweight aluminum cars that are energy-efficient and recyclable.

Diesel vs. Zero-Emission Trains 

diesel train illustration


  • Slower
  • Produces more greenhouse gas emissions
  • More expensive to maintain
zero emission train illustration


  • Faster
  • Stops and starts faster
  • Reduces greenhouse gas emissions
  • Less expensive to maintain
  • Holds more passengers

System Compatibility

Throughout the world and in the Bay Area, there are a number of other types of passenger rail systems in operation, such as light rail, monorail, cable cars, and streetcars.

Link21 will only consider the two train technologies that serve BART and Regional Rail. These two train technologies are in alignment with the Program’s goals and are consistent with voter-approved initiatives. They also meet the operating needs of BART, Capitol Corridor, and other Regional Rail systems in the Northern California Megaregion.

Read our fact sheet to learn more about future train technology.