3-layer staircase design

Quick answer：

A 3-layer staircase design refers to a staircase that is divided into three levels or sections. This type of design is often used in buildings with multiple stories to provide a visually appealing and functional way to connect the different levels. It can be found in residential, commercial, and public buildings. The design may vary in terms of the number of steps, the shape of the staircase, and the materials used. Safety and accessibility are key considerations in the design process.