what is an escalator

An escalator is a mechanical device used for transporting people vertically between different levels of buildings. It is a moving staircase consisting of a chain of single-piece aluminum or stainless steel steps guided by a system of tracks in a continuous loop. Escalators are commonly used in buildings where the movement of a large number of people is required, such as shopping centers, airports, transit systems, exhibition halls, hotels, arenas, public buildings, and so on. They occupy the same physical space as a staircase, generally have no waiting time (other than during periods of congestion), allow a greater flow of people, and can be more practical than lifts. Escalators typically rise at an angle of 30 or 35 degrees from the ground and move at 0.3–0.9 meters per second (1–3 ft/s) . They can traverse vertical distances in excess of 18 meters (60 ft) and have the capacity to move large numbers of people. A non-functional escalator can function as a normal staircase, whereas many other methods of transport become useless when they break down or lose power.