Annette Scogin, Age 10, of Little Rock, Ark., for her question:
WHEN WAS THE FIRST SUBWAY BUILT?
The world's largest subway system is the one operating in New York City. The first section of this giant network was opened in 1904. Today it is possible for a person to start a subway ride at the New Jersey shore, travel under the city and beneath two rivers into Long Island without once seeing daylight. New York's subway system runs on 235 miles of track.
A subway is an underground railway. It is strictly a big city system of transportation with the great ones being found in New York City, London, Paris and Moscow. Subways use a complicated network of tunnels.
London was the first city in the world to have a subway. Today, seven systems make up the city's vast network which provides inexpensive and quick transportation to all parts of the city and its suburbs.
In London, the subways are called tubes. Some are so far underground that it is necessary to travel on elevators to reach them.
The first subway built in London was operated by steam locomotives and it opened in 1863. The first deep level tube opened in 1890 and at this time the electric locomotive was put into operation. Since then, all subways have been operated by electricity.
Other major subways, and the dates when they first opened, include Madrid (1919), Barcelona (1924), Sydney (1926), Tokyo (1927), Buenos Aires (1928), Moscow (1935), Toronto (1954), Montreal (1966) and Mexico City (1969).
Boston was the first city in the United States to have a subway system. In 1897, a tunnel a mile and a half long was opened. Other American subways operate today in Chicago, Philadelphia, San Francisco and Washington, D.C.
One type of subway is called the open cut. Construction on this type is handled by digging deep ditches in the streets. Later pavement is put over the subway to form a tunnel where the tracks are placed.
A second type of subway is called the tube. Here the tunnel is completed by boring through the earth at the desired depth without disturbing the surface.
Subways must be built so that good ventilation is available. Stale air is carried off through vents while fresh air is usually brought into the system with fans.
Cost of subway systems is very high. Recent ones in San Francisco and Washington, D.C. cost a lot more than those in New York. New York's system cost from $2 million to $3 million per mile.