The long awaited Bay Area Rapid Transit (BART) extension to Pittsburg and Antioch, known locally as "eBART" (for East County BART), will begin service on Saturday, 5/26/18. The 10-mile system runs entirely down the median of Highway 4, between the Pittsburg/Bay Point BART station at Baily Road, and the new eBART station at Hillcrest Avenue in Antioch. There is one additional station stop, located at Railroad Avenue in Pittsburg.
Unlike traditional BART, eBART uses DMU's (Diesel Multiple Units) on standard gauged track.
Here is a link to the announcement from BART:
BART to Antioch press release
--James