Platform screen doors

Platform screen doors (PSDs) and platform edge doors (PEDs) at train or subway stations screen the platform from the train. They are a relatively new addition to many metro systems around the world, some having been retrofitted to established systems. They are widely used in Asian and European metro systems. The first station in the world with platform screen doors is Park Pobedy (Russian: Парк Побе́ды) in the Saint Petersburg Metro that was opened in 1961.

Door types
Although the terms are often used interchangeably, platform screen doors are full height, total barriers between the station floor and ceiling, while platform edge doors are full height but do not reach the ceiling and thus do not create a total barrier.

Platform screen doors
These doors help to:
 * Prevent accidental falls off the platform onto the lower track area, suicide attempts and homicides by pushing.
 * Prevent or reduce wind felt by the passengers caused by the piston effect which could in some circumstances make people fall over
 * Reduce the risk of accidents, especially from service trains passing through the station at high speeds.
 * Improve climate control within the station (heating, ventilation, and air conditioning are more effective when the station is physically isolated from the tunnel).
 * Improve security &mdash; access to the tracks and tunnels is restricted.
 * Lower costs &mdash; eliminate the need for motormen or conductors when used in conjunction with Automatic Train Operation, thereby reducing manpower costs.
 * Prevent litter build up on the track which can be a fire risk.
 * Improve the sound quality of platform announcements, as background noise from the tunnels and trains that are entering or exiting is reduced.

Their primary disadvantage is their cost; installing a system typically costs several million USD per station. When used to retrofit older systems, they limit the kind of rolling stock that may be used on a line, as train doors must have the exact same spacing as the platform doors; this results in additional costs due to depot upgrades and otherwise unnecessary purchases of rolling stock.

The doors also pose their own safety risks, as people maybe trapped by the doors; however, cases of this happening are extremely rare and such incidents have only occurred a few times in the history of installed platform screen doors.

Automatic platform gate
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 closed 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 are firstly 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 Gilgen Door Systems AG, have their gates higher than the one installed on Disneyland Resort Line.

Examples

 * Sentosa Express, Singapore
 * Mass Rapid Transit, Singapore - Platform Screen Door, all lines
 * North- South Terminal shuttle, London Gatwick Airport.

Singapore
The Singapore Mass Rapid Transit (MRT) was the first rapid transit system in Asia to incorporate platform screen doors in its stations in 1987. Full height PSDs are installed at all existing underground MRT stations in Singapore and all future underground MRT stations. Half-height platform screen doors have been retrofitted into all stations on 14 March 2012 (starting with three elevated MRT stations by 2009), as well as all future elevated MRT stations. The LRT Station at Sengkang also has platform screen panels installed.

There are two series of the full-height platform screen doors in use. The first was installed at all underground stations along the North South Line and the East West Line from 1987 to the completion of the initial system in 1990. The second series of PSDs sporting a sleeker design, producing less sound when the doors were opened and closed, and incorporating more glass were installed in the Changi Airport MRT Station which opened in 2002. All stations in the fully underground North East Line, which opened in 2003, sport these new doors. The Circle Line features second-generation platform screen doors on all of its stations. They were installed on the North South Line platform in the Bishan MRT Station in 2009 after the opening of the Circle line platforms there.

Considered a novelty at the time of its installation, it was introduced primarily to minimise hefty air-conditioning costs, especially since elevated stations are not air-conditioned and are much more economical to run in comparison. Since then the safety aspects of these doors have become more important, as highlighted by a series of high-profile incidents where individuals were injured or killed by oncoming trains since the year 2002 &mdash; all occurring on elevated stations with no screen doors. The Land Transport Authority reports that there have been more than 220 cases of commuters trespassing on the tracks between 1991 and 15 September 2004, of which 87 percent were deliberate acts of trespass. Nine fatalities were recorded during this period, of which only one was an accident. Since September 2004 there have been six fatalities occurring on elevated MRT and LRT stations.

Some of the Singapore Overground stations also had platform screen doors.