[talk-au] Join roundabouts

[Andrew Harvey]

For larger roundabouts I can see how the roundabout needs to be split and
the "from" member would be the roundabout segment, for smaller ones I can
see how the "from" would be the way leading into the roundabout and "to"
would be the way leading out of the roundabout and there would be no "via",
depends on the roundabout.

I haven't see anyone intentionally breaking things by merging, so I'd
strongly recommend to leave friendly changeset comments (if you haven't
already) because not everyone is on this list and for new contributors and
even experienced contributors mistakes happen, so changeset comments are
the best way to try and limit breakage in edits.

On Sat, 4 Apr 2020 at 22:52, Nemanja Bracko (E-Search) via Talk-au <
talk-au at openstreetmap.org> wrote:

> Hi,
>
>
>
> We could see that couple of users started joining ways that have an
> attribute *junction=roundabout* into single way.
>
> By doing so, we recognize following (potential) issues:
>
>    - We have added plenty of destination relations (overpass query
>    <https://overpass-turbo.eu/s/SlI>) across Australia, and by joining
>    roundabout ways into one, relation could be broken because members “from”
>    are lost. In the same time, “intersecting” members haven’t been added, so
>    the relation is invalid;
>    - If lanes (in real life) are changed within the roundabout (usually 2
>    lanes at some parts of the roundabout and 1 lane at the other), attributes
>    regarding lane information are lost;
>    - Route relations could also be broken;
>    - If junctions are NOT roundabouts (but have a circular/elliptical
>    shape), and ref id’s were correctly set, after joining ways, refs would
>    probably miss or just one would be present.
>
>
>
> Some examples:
>
> https://www.openstreetmap.org/way/717778304
>
> https://www.openstreetmap.org/way/39804616
>
> https://www.openstreetmap.org/way/717765311 - travaudat actually added
> “intersecting” role, but it is clear that lanes are changed within the
> roundabout
>
>
>
> I would ask users to try not to brake existing relations, and to note that
> multiple ways can be a part of single roundabout so it is not necessary to
> join these.
>
>
>
> Thank you,
>
> Nemanja
>
>
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>
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