Wikipedia: Rail transport

Rail transport has a long history, including systems with man or horse power and rails of wood or stone.

The advantages of rails are that you can predetermine the route that the carrage will travel, and decrease the frictional drag? by ensuring a smooth surface for the wheels to use. With the decreased drag, larger loads can be transported with the same amount of energy, which allows rail transportation to still have a lower cost per pound * mile ( or Kg * Km ) than lorries or trucks, planes or ships. A further advantage is provided by the loadspreading capability, especially of steel rails, allowing significantly greater loads per axle/wheel than in road transport.

The steam engine, introduced in the 19th century, was too heavy for the roads of the time, and the initial rails used were metal strips to spread the weight over wooden rails. One of the first usable steam powered engines was designed by George Stephenson with his locomotive, The Rocket, which was able to pull a train of two or three lightweight carrages.

Modern railroads with iron rails and steam-powered locomotives played an important part in the Industrial Revolution. In the late 19th century, railroads replaced earlier technologies such as horse-drawn boats in canals. In the 20th century, railroads were replaced, to a large extent, by motorized Road Transport. With the advent of containerized freight in the 1980s, rail and ship transportation have become an integrated network that move bulk goods very efficiently with a very low labor cost. An example is that goods from east asia that are bound for europe will often be shipped across the pacific and transfered to trains to cross North America and be transfered back to a ship for the atlantic crossing.

In Europe, as an added efficiency bonus, the railways have been electrified, so the trains do not have to carry fuel, and do not add much pollution. Both Europe, and Japan now have high speed [bullet trains]?, which approach two hundred kilometers per hour.

Inside major metropoliton areas, local trains designed to transport commuter?s, called the metro, subway, or underground, share the economics of rail transport.