[Tagging] stop area hierarchy

[Tijmen Stam]

On 16-11-16 16:23, Jo wrote:
> In bus stations all stops have names like Brussels North Station
> Platform 1", so all the names are different, which is why I created
> separate stop_area there too.
>
> This is the situation where I create most stop_area relations. For the
> 69000 other stops around the country I'm less keen on creating them.
> Same goes for the stop_area nodes on the ways. Usually which highway is
> used can be determined using 'proximity search', even when only nodes of
> the ways can be searched for (only nodes have coordinates in OSM).

This is quite a fundamental issue we have here!

I don't have a particular preference for either, but I think we should 
follow the same thing worldwide if we want to have any value to data 
handlers.


The wiki for stop_area 
<https://wiki.openstreetmap.org/wiki/Tag:public_transport%3Dstop_area> says:
"The public_transport=stop_area tag is used as part of a relation to 
identify all of the features associated with a public transport 
interchange or part of one. A stop area for a simple bus stop with buses 
in both directions would consist of two waiting areas or shelters which 
can be tagged using (public_transport=platform and/or highway=bus_stop) 
and two stop positions (using public_transport=stop_position). More 
complex stop areas may include multiple platforms and stop positions and 
many associated elements. "

Quoting a simple stop area with two platforms (Pl) and two stop 
positions (SP).

I could imagine the main advantage of having one SA for exactly one 
SP/Pl pair (+ associated shelters/benches/bins etc) would be that the 
relation between them is clear.

However, under the public_transport:version=2 scheme that link is laid 
in the route, which contains both a SP and a Pl. Even "weird" situations 
can be mapped such as two Pp / one SP (ex. two platforms on a busway 
directly opposite each other) or one Pl / two SP (ex. island platform 
mapped as node, way or area) by containing all in one SA, then having 
the routes include the proper SP/Pl combination

The advantage of a SA combining all SP/Pl is combining as much data on 
as high a level as possible (name, operator etc), even though that 
doesn't make much sense as I include the name in all three.

One disadvantage of one SA for multiple SP/Pl is the ambiguity of 
whether they should be mapped as "one". EG the 4 stops at 
<http://www.openstreetmap.org/#map=18/52.37096/4.87043&layers=Tz> have 
two called the Bilderdijkstraat (in the De Clercqstraat) and two called 
De Clercqstraat (in the Bilderdijkstraat), should they be one or two (or 
in Jo's system: 4) stops?

(Interestingly: Openbusmap renders them as two, in a cross, but just one 
junction south the similar junction Kinkerstraat/Bilderdijkstraat is 
mapped as one... 
https://www.öpnvkarte.de/index.html#4.872242074908898;52.36777234510416;18)


So, we should decide one of the two... but which one?

Tijmen