Cross-platform interchange

A cross-platform interchange is a type of interchange between different lines at a metro (or other railway) station. The term originates with the London Underground; such layouts exist in other networks but are not commonly so named. In the United States, it is often referred to as a "cross-platform transfer".

This configuration occurs at a station with island platforms, with a single platform in between the tracks allocated to two directions of travel, or two side platforms between the tracks, connected by level corridors. The benefit of this design is that passengers do not need to use stairs to another platform level for transfer, thus increasing the convenience of users. A cross-platform interchange arrangement may be costly due to the complexity of railtrack alignment, especially if the railway designers also arrange the track with flyovers (which is typically done to increase efficiency). A common two-directions cross-platform interchange configuration consists of two directions of two different lines sharing an island platform, and the respective return directions of both lines sharing a different island platform in the same station complex.

Common cross-platform interchanges allow passengers to change trains without changing to another platform. This applies at places where trains of different directions meet in minor and major hubs, but this arrangement is only found at some interchange stations in metro and other rail networks worldwide.

Some railway lines, usually in more congested areas, also offer cross-platform interchanges between different categories of trains, for example between express and stopping ("local") trains. For instance, this kind of interchange is used at many European railway minor hubs to connect fast trains to local feeder services, as well as surface sections of suburban lines like the RER E in Paris or the Metro North Hudson Line in New York State. However, local–express interchanges are found in only a few metro networks, such as Chicago, Chengdu, London, New York City, and Philadelphia. The New York City Subway system has numerous stations facilitating cross-platform transfers between local and express trains, typically using pairs of island platforms, each serving express trains on one side, and local trains on the other side, with both alternatives headed in the same direction.

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