Subway

Subway, passenger vehicle that usually has multiple cars and steel wheels, and generally runs on rails traveling underground. Subways serve as part of many urban systems of public transportation; millions of people in the United States rely on subways for daily travel.

Subway systems are sometimes categorized as rapid rail transit, also called heavy rail transit. Subway trains can reach speeds of up to 120 to 130 km/h (up to 75 to 80 mph) and carry as many as 40,000 passengers per hour in one direction. They may operate in tunnels, on elevated structures, or in exclusive rights-of-way that are separate from other traffic. A hybrid of subways and streetcars, called subsurface cars, travel like electric streetcars for part of their route and then go underground for other parts of their trip.

Subway trains run on a pair of rails and are usually powered by electricity from a third rail. Typically, passengers gain access to the subway platform by passing through turnstiles that require payment. Riders may pay the subway fare with money or tokens, or they may purchase a pass for a specific period of time. Most trains have a driver, but some are remotely controlled. Often, passenger cars can be added or subtracted at either end of the subway train.

The first subway, which began operating in 1863 in London, England, used steam locomotives. The subway was successful, and it expanded, converting to electricity in about 1896. That same year Budapest, Hungary, became the first city on the European continent to open an electric subway line. Other European cities followed with similar lines.

The first electric subway line in the United States opened in Boston, Massachusetts, in 1897 to immediate success. New York City followed in 1904 with approximately nine miles of subway track. New York’s subway system is now one of the world’s largest, covering hundreds of miles.

Subways primarily serve highly populated metropolitan areas. Because of this core of passengers, subways have not been as challenged as other forms of mass transit to maintain their rider base during the past half-century. In addition, such systems are comparatively environmentally-sound and inexpensive to operate, and their use helps mitigate traffic congestion.