Rail transit

Trains are vehicles that operate on tracks.

In transit/railroad terms, a car means a single rail vehicle. A train means multiple rail cars connected together (2-car trains, 5-car trains).

Passenger trains vary in speed and distance. Some trains in the East Coast and abroad can operate faster than 125 mph connecting major cities. Some rail lines in the Bay Area function like a local bus with stops every few city blocks.

Types of passenger trains

High speed trains

High speed trains are generally defined as trains that can operate 125mph or faster. High speed trains generally connect large metropolitan areas (with very few stops in between) and are competitive with airlines in terms of overall travel time.

There's a proposal to construct a high speed rail system between the Bay Area and Southern California via the Central Valley.

Inter city trains

Inter-city trains generally mean trains traveling long distances connecting metropolitan areas. Although the distances covered by some of these trains are comparable to airlines, inter-city trains generally operate at highway speed. Long distance inter-city trains may provide amenities not found on most other forms of transportation, including sleeper-cars and cafe/dining cars.

Amtrak is the operator of inter-city trains in the United States.

Although riding Amtrak is much slower than flying, inter-city trains are nonetheless valuable. Between metropolitan areas, Amtrak trains serve small cities that aren't served by airlines.

Commuter trains

Commuter trains generally mean trains connecting suburban areas with the central city and primarily serves riders to and from work. Commuter trains typically run on weekdays, during rush hours, and only in the peak direction. A prime example would be Altamont Commuter Express, which run from Stockton to San Jose during weekday mornings, and from San Jose to Stockion during weekday afternoons.

Commuter trains however can run more service than what the category typifies. Caltrain for instance operates 7-days a week with all-day train service in both directions. Many also considers BART to be commuter rail because of suburbs the system serves.

Rapid transit

Rapid transit, which also known as metro, subway, and heavy rail, mean trains that generally serve the city-core, have large passenger capacity, and operate totally separate from road traffic. In order to run separately from road traffic in the city-core, rapid transit trains would run either above or underground.

Many major cities (like New York, London, Washington D.C.) have extensive systems that make traveling within a city fast and convenient. BART is the rapid transit system in the Bay Area. However, BART does not serve San Francisco as extensively as other systems do in other cities.