To ensure safety of passengers, full height platform screen doors are normally installed on all underground stations and half-height screen doors on all elevated stations. These doors will remain closed while passengers are waiting for the trains to come, and will open only after the train arrives through the sensor system. These platform doors are synchronized with the doors of the trains, and when trains leave the platform, they close automatically, preventing access to the tracks for the waiting passengers.
In stations, where screen doors / gates are installed, the rail tracks are not visible to the passengers, so much so, it is a fool-proof safety system by preventing unauthorized access to restricted areas. On stations, where half-height screen doors, are installed passengers have no access to the tracks, though tracks are visible from outside. Automatic half-height platform screen doors are chest-high 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.
These safety doors helps a great way in reducing the risk as under :
It will prevent accidental falls off the platform onto the lower track area, suicide attempts and homicides by pushing on to the tracks.
If full-height screen doors are installed, it will reduce the wind felt by the passengers caused by the piston effect which could in some circumstances make people fall over.
It eliminates the risk of accidents, especially from service trains passing through the station at high speeds.
Where full-height screens are installed, it will improve climate control within the station (heating and air conditioning are more effective when the station is physically isolated from the tunnel).
It will improve security-access to the tracks and tunnels is restricted.
It may prevent litter or no build up on the track which can be a fire risk.
It improves the sound quality of platform announcements, as background noise from the tunnels and trains that are entering or exiting is reduced.