Moving stairs

An escalator is a type of vertical transportation in the form of a moving staircase which carries people between floors of a building. It consists of a motor-driven chain of individually linked steps on a track which cycle on a pair of tracks which keep them horizontal.

Escalators are used around the world in places where elevators would be impractical. Principal areas of usage include department stores, shopping malls, airports, transit systems (railway/railroad stations), convention centers, hotels, arenas, stadiums and public buildings.

Escalators have the capacity to move large numbers of people. They can be placed in the same physical space as a staircase. They have no waiting interval (except during very heavy traffic). They can be used to guide people toward main exits or special exhibits. They may be weatherproofed for outdoor use. A nonfunctional escalator can function as a normal staircase, whereas many other methods of transport become useless when they break down or lose power.

Escalators are typically rise at an angle of about 30 degrees from the horizontal. ground. They move at 0.3–0.6 metres (1–2 ft) per second (like moving walkways) and may traverse vertical distances in excess of 18 metres (60 ft). Most modern escalators have single-piece aluminum or stainless steel steps that move on a system of tracks in a continuous loop.

Escalators are typically configured in one of three ways: parallel (up and down escalators adjacent or nearby, often seen in metro stations and multilevel movie theaters), multiple parallel (banks of more than one escalator going in the same direction parallel to banks going the other direction), or crisscross (escalators going in one direction "stacked" with escalators going the opposite direction oriented adjacent but perpendicular, frequently used in department stores or shopping centers).

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Wikipedia