Platform screen doors, continuous barriers custom-designed for subway station platforms, play a crucial role. They cleverly separate the platform waiting area from the track area, precisely corresponding to train doors, and possess multi-level control for opening and closing. In terms of enclosure type, platform screen doors can be divided into semi-enclosed and enclosed types. Semi-enclosed platform screen doors, often simply called "safety doors," are used solely for safety and aesthetic purposes, particularly suitable for platforms without air conditioning systems, such as ground-level or elevated platforms. Enclosed platform screen doors, on the other hand, are more suitable for platforms equipped with air conditioning systems, such as underground platforms, and are therefore the most commonly used type of platform screen door. Furthermore, semi-enclosed, semi-height platform screen doors, as a unique design, offer flexible options of full-height and half-height options with their open glass partitions and movable doors.
Full-height platform screen doors have a door height significantly exceeding human height, with an open space between the top of the door and the station hall ceiling, lacking a sealing function. These types of safety doors are mainly suitable for underground stations. Although their structural form is similar to enclosed systems, the upper part of full-height platform screen doors is designed to be open.
In contrast, half-height safety doors are no taller than a person and also lack a sealing function. Because this design cannot completely block the impact of wind and noise on passengers, it is more commonly used in ground-level and elevated stations.
