[Tagging] rail routes: how are platforms and stops associated (rail question 2)

[Michael Reichert]

Hi Bjoern,

Am 2017-05-11 um 11:17 schrieb Bjoern Hassler:
> in the case of 4a/4b etc I would put in different stop points. If 4a always
> serves one route, then 4a would be added to the route relation. Maybe if 4a
> / 5a / 6a can all serve the same route, then I don't know what the solution
> is.... Maybe you just add a new stop point somewhere, and add a note? Or
> put 4a/5a/6a into a relation, and add the relation? (That would be against
> the spec at the moment I think... but could be a solution.)

If some trains of a line serve platform 4, some 5 and some 6, only map
the variant which is served most frequent on a working day or over a
week. In some countries the platform where a train stops is announced
only a few minutes before its arrival (e.g. in France and Czech Republic).

> Colin: Actually, in the case you mentioned (short/long trains), I guess
> there could also be several stop points. I think that's not a problem. It's
> just you would only add one of those to the route relation. For the several
> stop points, ideally there would be a note, saying "front of train, 4
> carriages" or "front of train, 8 carriages", or maybe an additional tag of
> some kind.

Just map the location of the center of the shortest train which serves
this route. This will lead passengers always to the location on the
platform where they most probably can enter a train.

> To come back to the original question: If an association between a stop
> point and platform exists (as it does on the underground), is there a way
> of indicating this through tagging? What are your views?
> 
> There are a few possibilities, e.g. both the stop point and the platform
> could share the same name (kinda fragile though). They could be ordered in
> the relation so that the stopping_position comes first, followed by the
> platform (this would be a new feature, but e.g. a tag could be added to the
> route relation where this ordering has taken place). Also, the roles in the
> route are stop/platform, but also suggest stop:n / platform:n. It's not to
> order them, and it doesn't look like this is to associate stop/platform,
> but it could be used.

Valid PTv2 route relations are ordered, i.e. the platform which follows
a stop position and is near the stop position always belongs to the stop
position.

Best regards

Michael

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