[Tagging] ref on roundabout

Florian Lohoff f at zz.de
Sun Aug 23 13:23:19 UTC 2020

On Sat, Aug 22, 2020 at 01:28:07PM +0200, Mateusz Konieczny via Tagging wrote:
> Aug 22, 2020, 12:17 by f at zz.de:
> > On Sat, Aug 22, 2020 at 12:09:14PM +0200, Mateusz Konieczny via Tagging wrote:
> >
> >> I would expect roundabout to be split in parts where
> >> ref is applying and parts where it is not applying, in other words
> >> without any special handling and tag it as usual.
> >>
> >
> > But the point is that on a roundabout the "name" references the name
> > of the _roundabout_ not one of the streets connected to it. 
> >
> Yes
> > Same should apply to ref as it will reference the Roundabout
> why?

1. How do you tag a reference number for a roundabout when suddenly
the ref contains a ref of one of the streets?
2. Inconsistency - Some informations on the roundabout contain
informations about itself, and some are just copied over from 
attached streets.

> So it is about case where road has its own reference number
> and junction has its own reference number, separate from
> reference number of road routes?

Yes - We should be consistent that an object carries informations about
itself and ONLY itself and not carry on some information of related
objects. To glue objects together or describe their relation 
we typically use relations. We do this in Germany a lot - So primary
roads typically have relations carrying all road segments including
the roundabout. 

> In Poland road route continues through roaundabout and roaundabout way
> is part of such route.

Correct - In Germany - at least for "StraรŸen NRW" thats the same. The
road surface of the roundabout is part of the Road through it. But
nevertheless - OSM has had a different Data Model to address/reference
roundabouts itself to be able to do landmark routing e.g

"Take 1st exit at the Hampstead Roundabout, then take the 2nd exit at
the Foobar Roundabout".

For this to work you have to put the information about the roundabout
itself somewhere. This has been documented for ages to be the
way carrying the junction=roundabout which has a name tag on its own.

So using ref on the roundabout for either the road, or a reference
of the roundabout breaks the assumptions that informations on the
junction=roundabout only refer to the roundabout. With this concept
it may sometimes refer to one or more roads which are connected to the
roundabout. This basically makes the information useless.

Florian Lohoff                                                 f at zz.de
        UTF-8 Test: The ๐Ÿˆ ran after a ๐Ÿ, but the ๐Ÿ ran away
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