Five Lines for the Bay Area

The Bay Area Rapid Transit (BART) system serves San Francisco and portions of San Mateo, Alameda and Contra Costa Counties.  It extends far beyond the traditional urban core, with its fares increasing in general with the distance traveled, and thus BART also bears some resemblance to a commuter rail network.

There are five lines operated.  Four start on the San Francisco Peninsula in either Daly City, San Francisco International Airport or Millbrae, and utilize the subway under Market St. through downtown San Francisco and then the Transbay Tunnel before splitting off to reach different East Bay destinations.  The fifth line stays in the East Bay. 

This photo is looking south from Platform 3 at Daly City, first stop south of the city limits of San Francisco.