An island platform (also center platform (American English) or centre platform (British English)) is a station layout arrangement where a single railway platform is positioned between two railway track within a railway station, tram stop or transitway. Island platforms are sometimes used between the opposite-direction tracks on twin-track route stations as they are cheaper and occupy less area than other arrangements. They are also useful within larger stations, where local and express services for the same direction of travel can be accessed from opposite sides of the same platform instead of on either side of the tracks, simplifying and speeding transfers between the two tracks.
The historical use of island platforms depends greatly upon the location. In the United Kingdom the use of island platforms on twin-track routes is relatively common when the railway line is in a cutting or raised on an embankment, as this makes it easier to provide access to the platform without walking across the tracks.
Advantages and tradeoffs
If an island platform is not wide enough to cope with passenger numbers, typically as they increase, overcrowding can risk people being pushed onto the tracks. In some cases, entry to the station is restricted at busier times to reduce risk. Examples of stations where a narrow island platform has caused safety issues include Clapham Common and Angel (rebuilt in 1992) on the London Underground, Union (rebuilt in 2014) on the Toronto subway, and on the Osaka Municipal Subway.
An island platform requires the tracks to diverge around the centre platform, and extra width is required along the right-of-way on each approach to the station, especially on high-speed lines. Track centres vary for rail systems throughout the world but are normally . If the island platform is wide, the tracks must slew out by the same distance. While this requirement is not a problem on a new line under construction, it makes building a new station on an existing line impossible without altering the tracks. A single island platform also makes it quite difficult to have through tracks (used by trains that do not stop at that station), which are usually between the local tracks (where the island would be).
A common configuration in busy locations on high speed lines is a pair of island platforms, with slower trains diverging from the main line (or using a separate level on the railway's right-of-way) so that the main line tracks remain straight. High-speed trains can therefore pass straight through the station, while slow trains pass around the platforms (such as at Kent House in London). This arrangement also allows the station to serve as a point where slow trains can be passed by faster trains. A variation at some stations is to have the slow and fast pairs of tracks each served by island platforms (as is common on the New York City Subway; the Broad Street Line of SEPTA; and the Chicago Transit Authority's Red and Purple lines). A rarer layout, present at Mets-Willets Point on the IRT Flushing Line, 34th Street – Penn Station on the IRT Seventh Avenue Line and 34th Street – Penn Station on the IND Eighth Avenue Line of the New York City Subway, uses two side platforms for local services with an island in between for express services. The purpose of this atypical design was to reduce unnecessary passenger congestion at a station with a high volume of passengers. Since the IRT Seventh Avenue Line and IND Eighth Avenue Line have adjacent express stations at 42nd Street, passengers can make their transfers from local to express trains there, leaving more space available for passengers utilizing intercity rail at Pennsylvania Station. The Willets Point Boulevard station was renovated to accommodate the high volume of passengers coming to the 1939 World's Fair.
Examples
Almost all railway stations in India have island platforms.
Australia
Canada
In Edmonton, all 18 LRT stations on the Capital Line and Metro Line used island platforms until NAIT/Blatchford Market station opened in 2024, the only station with side platforms as of 2024. The Valley Line Southeast uses low-floor LRT technology, but uses island platforms on only two of the 12 stops, Mill Woods and Davies station.
Singapore
United States
The NYC Subway has many stations with island platforms, including all of the Second Avenue Subway stations.
Unused sides of island platforms
In New York City's subway system, unused sides are located at Bowling Green as well as every express station without express service, such as Pelham Parkway on the IRT Dyre Avenue line. In Jersey City, the Newport PATH station has the same configuration as Bowling Green—one side platform and one island platform.
On the Tokyo Metro, the Ginza Line has a side platform and an island platform at . Likewise, the and stations on the Osaka Metro have similar configurations. On JR East, the Yokosuka Line platforms at feature a similar setup following a new side platform opening in December 2022.
Some stations of the Glasgow Subway have one island platform and one side platform (Hillhead, Buchanan Street, and Ibrox).
In Wellington, New Zealand, unused sides can be found at two stations on the Hutt Valley Line: Waterloo and Petone. Waterloo's island platform was reconfigured to be the down side platform when the station was extensively rebuilt in the late 1980s, with the unused side now facing onto a bus bay. Petone's island platform served the up main line and the suburban loop line until the suburban loop was lifted in the early 1990s. The unused platform now faces onto the station's park-and-ride carpark.
Gallery
See also
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