Mapping train platforms subareas and markers

Hello. For about one year now, there is a project on-going with NBMS/SNCB (the Belgian railway public service) about mapping railway stations. A next step is to map platform sub-area and sub-areas markers: meaning a railway platform that gives access to a train line but which is subdivided in 2 or more parts along the track, deserving the same train or not, typically numbered with letters: A, B, … I have some questions about the data models currently used and documented.

Mapping the marker denoting the subareas

  • A dedicated tag seems to exist: railway=platform_marker

  • see FR:Tag:railway=platform_marker - OpenStreetMap Wiki. The pictures in this wiki page are exactly what I mean by platform subareas in the Belgian context.

  • usage: only in France (416 items) and in Algeria (1 item)!

This seems a very nice solution, but, just a question: is another tag (railway=signal + railway:signal:stop ?) used outside France (and Algeria)?

Mapping the platform sub-areas

1) Use “railway:part = platform”

2) Use “railway=platform” for mapping individual platform subarea

It seems the common usage, but it brings several drawbacks:

  • info on the platform like height, surface, etc. can be duplicated, thus prone to maintenance errors

  • more complex for data consumption: for our use case of data consumption, we’d like to identify only one platform by railway stop, because we want to identify the access objects that exist on the platform. Of course, adjacent platforms can be merged when consuming the data, but this bring several fragilities and drawbacks (what we do of divergent tag values, are the adjacent platform really accessible for the travelers, …)

3) Use “railway=platform_edge”

The problem of one platform for 2 stops and the problem of the platform subareas is maybe solved by the usage of platform_edge.

The only thing is that it is mapped as a way (line), not an area. Usually, this line is then used for mapping the railway=platform area as a relation, with the platform_edge as one of the outer way. Seems widely used in Germany, but not in Belgium where the railway=platform as a closed way is preferred.

I’d like to hear here about what would be an appropriate data model for the train platforms, including these two open questions:

  • how to deal with the fact that a platform generally gives access to 2 tracks, e.g. track 1 and 2? Map one unique platform with ref=1;2 or map 2 separate platforms?

  • how to deal with platform subareas, like 1A, 1B, 2A, 2B? Map them separately? Superimpose platforms? Use railway:part=platform (area) and/or railway=platform_edge (line)?

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