Three-rotary staircase plan

Quick answer：

A three-rotary staircase plan refers to a design for a staircase with three levels that rotate around a central axis. It is a type of multi-level staircase commonly used in buildings to connect different floors in a space-saving manner. The design allows for a continuous flow of traffic as people move between levels. This type of staircase can be found in high-rise buildings, shopping malls, and other public facilities.