Platform screen doors


Platform screen doors, also known as platform edge doors, are used at some train, rapid transit and people mover stations to separate the platform from train tracks, as well as on some bus rapid transit, tram and light rail systems. Primarily used for passenger safety, 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 newer Asian and European metro systems, and Latin American bus rapid transit systems.

History

The idea of platform edge doors dates from as early as 1908, when Charles S. Shute of Boston was granted a patent for "Safety fence and gate for railway-platforms". The invention consisted of "a fence for railway platform edges", composed of a series of pickets bolted to the platform edge, and vertically movable pickets that could retract into a platform edge when there was a train in the station. In 1917, Carl Albert West was granted a patent for "Gate for subrailways and the like". The invention provided for spaced guides secured to a tunnel's side wall, with "a gate having its ends guided in the guides, the ends and intermediate portions of the gate having rollers engaging the side wall". Pneumatic cylinders with pistons would be used to raise the gates above the platform when a train was in the station. Unlike Shute's invention, the entire platform gate was movable, and was to retract upward.
File:Lomonosovskaya metrostaion-doors open.JPG|thumb|upright=1.3|"Horizontal lift" style doors at Lomonosovskaya station on the Saint Petersburg Metro, the first screen doors in the world
The first stations in the world with platform screen doors were the ten stations of the Saint Petersburg Metro's Line 2 that opened between 1961 and 1972. The platform "doors" are actually openings in the station wall which supports the ceiling of the platform. The track tunnels adjoining the ten stations' island platforms were built with tunnel boring machines, and the island platforms were located in a separate vault between the two track tunnels. Usually, TBMs bore the deep-level tunnels between stations, while the station vaults are dug out manually and contain both the tracks and the platform. However, in the case of the Saint Petersburg Metro, the TBMs bored a pair of continuous tunnels that passed through ten stations, and the stations themselves were built in vaults that only contained the platform, with small openings on the sides of the vault, in order for passengers to access the trains in the tunnels.
Singapore's Mass Rapid Transit, opened in 1987, is often described as the first heavy Metro system in the world to incorporate PSDs into its stations for climate control and safety reasons, rather than architectural constraints, though the light Lille Metro, opened in 1983, predates it.

Types

Although the terms are often used interchangeably, platform screen doors can refer to both full-height and half-height barriers. Full height platform screen doors are total barriers between the station floor and ceiling, while the half-height platform screen doors are referred to as platform edge doors or automatic platform gates, as they do not reach the ceiling and thus do not create a total barrier. Platform gates are usually only half of the height of the full-screen doors, are chest-height sliding doors at the edge of railway platforms to prevent passengers from falling off the platform edge onto the railway tracks. But they sometimes reach to the height of the train. Like full-height platform screen doors, these platform gates slide open or close simultaneously with the train doors. These two types of platform screen doors are presently the main types in the world.

Platform screen doors and platform edge doors

The doors help to:
  • Prevent people from accidentally falling onto the tracks, getting too close to moving trains, and committing suicide or homicide. Use of platform screen doors in South Korea has reduced rail related suicide by 89%.
  • Prevent or reduce wind felt by the passengers caused by the piston effect which could in some circumstances make people lose their balance.
  • Improve safety—reduce the risk of accidents, especially from trains passing through the station at high speeds.
  • Improve climate control within the station. Installation of platform screen doors on Seoul's subway improved cooling efficiency by 30%, which saves 16.7 billion won annually.
  • Improve security—access to the tracks and tunnels is restricted.
  • Lower costs—eliminate the need for motormen or conductors when used in conjunction with automatic train operation, thereby reducing manpower costs.
  • Prevent litter buildup on the tracks, which can be a fire risk, as well as damage and possibly obstruct trains.
  • Improve the sound quality of platform announcements, as background noise from the tunnels and trains that are entering or exiting is reduced.
  • At underground or indoor platforms, prevent the air from being polluted by the fumes caused by friction from the train wheels grinding against the tracks. Fine dust levels reduced by approximately 20% after installation of platform screen doors on Seoul's subway.
Their primary disadvantage of PSDs is their cost. When used to retrofit older systems, they can limit the kind of rolling stock that may be used on a line, because the train doors must fit the spacing of the platform doors, which can result in additional costs, due to the otherwise unnecessary purchase of new rolling stock and consequent depot upgrades.
Despite delivering an overwhelming improvement to passenger safety at the platform-train interface, platform screen doors do introduce new hazards which must be carefully managed in design and delivery. The principal hazard is entrapment between closed platform doors and the train carriage which, if undetected, can lead to fatality when the train begins to move. Cases of this happening are rare, and the risk can be minimised with careful design, in particular by interlocking the door system with the signalling system, and by minimising the gap between the closed platform doors and the train body. In some cases active monitoring systems are used to monitor this gap.
Half-height platform edge doors, also known as automatic platform gates, are cheaper to install than full-height 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 in practical use by the Hong Kong MTR on the Disneyland Resort line for the open-air station designs. Most half-height platform edge door designs have taller designs than the ones installed on the Disneyland Resort line.

Rope-type platform screen doors

There are also rope-type platform screen doors at stations where a number of train types, with different lengths and train door spacings, use the same platforms. The barriers move upwards, rather than sideways, to let passengers through.
Some Japanese, Korean, Chinese and Eastern European countries have stations that use rope-type screen doors, to lower the cost of installation and to deal with the problem of different train types and distances between car doors.

Variable-type platform screen doors

The first-ever full-height variable screen doors were installed on the underground platforms of Osaka Station, which opened in March 2023, but a few half-height variants can be found on a set installed at the Shinkansen platforms of Shinagawa Station in Tokyo. Their use is rare since they are a much costlier and more complicated alternative to rope-type screen doors. The only difference from the latter is that they move sideways when letting passengers through.
At Osaka Station, the doors are designed as a single block. It consists of five units: one wall-like "parent door" suspended from the top and two sets of glass "child doors". When the train reaches the station, a special scanner on the platform reads the information on the ID tag placed on the train to identify its type and the number of cars. With the type and the number of cars having been instantly identified, each unit will slide automatically to match the configuration of the stopped train. The parent and child doors then slide into the optimal position to align precisely with the position of each car door.
Since the technology is still new, such doors are still going through testing phases in several countries around the world.

Use

Argentina

of the Buenos Aires Subte is planned to have platform screen doors installed in the future, after the communications-based train control system has been installed.

Australia

, which opened in May 2019, was the first-fully automated rapid transit rail system in Australia. There are full-height screen doors on most underground platforms, with full-height edge doors on at-grade, elevated and some underground platforms. The existing five stations on the Epping to Chatswood railway line were upgraded to rapid transit standard, all being fitted with full-height platform edge doors.
In Melbourne, the Metro Tunnel, from South Kensington to South Yarra, which opened in November 2025, has platform screen doors on the underground stations. New rolling stock has been constructed specifically with doors that will line up with full-height PSDs on the platforms. The fully automated Suburban Rail Loop, which is due to open in 2035, will have platform screen doors at every station.
The Cross River Rail in Brisbane, which is currently under construction and scheduled to open in 2026, will have platform screen doors on the new Boggo Road, Woolloongabba and Albert Street underground stations, and the new underground platforms of Roma Street station.