[Tagging] Highway=*_link roads at Y-junctions and roundabouts?

[Markus]

On Sun, 16 Dec 2018 at 01:24, Joseph Eisenberg
<joseph.eisenberg at gmail.com> wrote:
>
> While checking the rendering of highway link roads (eg motorway_link,
> primary_link, tertiary_link), I noticed that in some cases these tags
> are used when a road splits in a Y-junction, for example before a
> traffic circle / roundabout. In some areas these are the most common
> forms of _link for less major roads, eg secondary_link and
> tertiary_link.

I'd say that a road is only a highway link if it doesn't belong to one
or the other road. For example, this roundabout entrance

https://www.openstreetmap.org/way/631552692

clearly belongs to the secondary road 144, whereas this road section

https://www.openstreetmap.org/way/201572456

which bypasses the roundabout, belongs neither to the secondary road
144 nor the primary road 9. And regarding this short road section at
an intersection

https://www.openstreetmap.org/way/421827471

it's also clear that it geometrically belongs to Avenue de Blonay
instead of Rue des Chenevières.

> Examples of tertiary_link used at a roundabout (rendered thinner in
> these examples)
> https://user-images.githubusercontent.com/42757252/50000948-8e4c7c80-ffde-11e8-8718-3446aefe7ab6.png

As in my examples above, i'd tag the bypass in the southwest _link,
but not the entrances and exits of the roundabout.

> https://user-images.githubusercontent.com/42757252/50000961-9a383e80-ffde-11e8-8d7a-cd85f4dbf125.png

Again, i wouldn't tag the roundabout entrances and exits _link. Those
are just short road sections that are dual carriageway.

> Here are some debatable places where a tertiary_link might be tagged
> at a Y-junction:
> https://www.openstreetmap.org/node/412162671

Seems fine to me without _link.

> https://www.openstreetmap.org/node/2539835932

There's just a triangular painted island, that means it's just one
carriageway. Therefore i'd rather not map two one-way road sections
there (see https://wiki.openstreetmap.org/wiki/Highways#Carriageways).

Regards
Markus