Caltrain tests battery-electric train in daylight to Gilroy

Caltrain rail operations engineers launched daytime dynamic track testing on Friday morning for the agency's first bi-level Battery-Electric Multiple Unit (BEMU) trainset between San Jose Diridon Station and the Gilroy terminal, marking a milestone toward replacing the last diesel-hauled commuter trains in southern Santa Clara County. Built by Stadler at its Salt Lake City assembly facility, the four-car hybrid trainset draws 25-kilovolt overhead catenary power while running between San Francisco and Tamien Station, simultaneously recharging its roof-mounted lithium-titanate traction battery packs. Once south of Tamien, the engineer lowers the pantograph at track speed and switches seamlessly to onboard battery propulsion for the non-electrified 30-mile Union Pacific corridor through Morgan Hill and San Martin to Gilroy.

During Friday's instrumentation runs out of the Central Equipment Maintenance and Operations Facility on Lenzen Avenue in San Jose, propulsion specialists verified regenerative braking recovery rates, automatic train control signaling handoffs, and thermal battery cooling across simulated peak commuter loads. Data collected from onboard telemetry showed the battery packs retaining a 38 percent state-of-charge reserve after completing a 60-mile round-trip between Tamien and Gilroy without wayside charging at the southern terminal.

Following the September 2024 launch of fully electrified service between San Francisco and San Jose—which boosted systemwide Caltrain ridership by more than 40 percent over the past two years—South County riders have remained dependent on aging diesel locomotives for four weekday round-trips. Introducing the battery-electric fleet will allow single-seat, zero-emission journeys all the way from Gilroy to Fourth and King Station in San Francisco while cutting corridor greenhouse gas emissions by an additional 9,400 metric tons per year.

Federal Railroad Administration acceptance trials will continue on weekday middays through December before passenger demonstration runs begin in early 2027. Commuters can view the South County electrification testing schedule and technical specifications on the Caltrain Fleet Electrification Portal.