Caltrain is a commuter rail service on the San Francisco Peninsula connecting San Francisco to San Jose and Gilroy. During the third quarter of 2010, it served about 41,000 riders each weekday via 32 stations on 77.4 miles of track. They operate a mix of 43 weekday local, limited, and Baby Bullet express trains in each direction daily along the San Jose and San Francisco route, with three daily round-trips extending to Gilroy. Weekend service includes 18 trains in each direction, and the agency is currently experimenting with weekend Baby Bullet express trains.

The fastest Baby Bullet trains from San Francisco to San Jose take about 57 minutes – on local trains, the trip can be as long as 1 hour and 36 minutes. Caltrain uses a zone-based fare structure, and the aforementioned trip would garner a regular adult one-way fare of $7.75.

Caltrain operates a number of GM Electro-Motive locomotives and has two types of coaches currently in service – Nippon Sharyo bi-level gallery cars are typically used on local and limited trains, while newer Bombardier Bi-Level coaches are used on Baby Bullet express service.

Caltrain is operated by the Peninsula Corridor Joint Powers Board, which is a coalition made up of the San Francisco Municipal Transportation Agency, the San Mateo County Transit District, and the Santa Clara Valley Transportation Authority. Because the commuter railroad primarily relies on decreasing contributions from these financially-struggling agencies, it is facing a serious financial crisis that will likely lead to a drastic cut in service.

Despite the financial concerns, several enhancements are being pursued at this time – most notably, Caltrain’s northern terminus is being extended from 4th and King in San Francisco into the middle of downtown at 1st and Mission (the extension will also be served by California High Speed Rail, which will travel along the Caltrain corridor between San Jose and San Francisco). Caltrain also plans to switch to electric operation, and the introduction of HSR will require the elimination of all at-grade crossings on the corridor. Planned extensions of Caltrain across the Dumbarton Bridge into the East Bay and southward from Gilroy to Salinas have been delayed.