Automatic platform gates (or half-height platform screen doors as referred to by some manufacturers) are chest-height sliding doors at the edge of railway platforms to prevent passengers from falling off the platform edge onto the railway tracks. Like full-height platform screen doors, these platform gates slide open or close simultaneously with the train doors.
Half-height platform gates are cheaper to install than platform screen doors, which require more metallic framework for support. Some railway operators may therefore prefer such an option to improve safety at railway platforms and, at the same time, keep costs low and non-air-conditioned platforms naturally ventilated. However, these gates are less effective than full platform screen doors in preventing people from intentionally jumping onto the tracks.
These gates were first in practical use by Hong Kong metro system, MTR on Disneyland Resort Line for their open-air stations design. The later design by other manufacturers, such as Manusa or Gilgen Door Systems AG, have their gates higher than the one installed on Disneyland Resort Line.
Examples
A few examples include: