[Tagging] stop area hierarchy
Tijmen Stam
mailinglists at iivq.net
Thu Nov 17 20:56:11 UTC 2016
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
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