Escalator

An escalator having an entrance and an exit zone, the escalator comprising:

• a series of steps having a tread and at least one riser underneath, wherein at least one of said series of steps is a vertically adjustable step, adjustably positionable to have an upper surface that is substantially coplanar with an upper surface of an adjacent non vertically adjustable step;
• an advance track for circulating the steps, the advance track comprising a set of lateral main guides on which the series of steps move by means of front and rear bearings on both sides of said steps, the advance track further comprising at least one set of additional guides for the movement of the at least one vertically-adjustable step, wherein the advance track includes first and second ends;
• a return track of the steps;
• and
• intermediate transition zones between the advance track and the return track, the intermediate transition zones having a set of transition zone guides,
• wherein set points are arranged at the first and second ends of the advance track, in correspondence with the entrance and exit zones of the escalator, for the positioning and returning of the movable steps between at least one of the set of transition zone guides, the set of main guides and the at least one set of additional guides.