[Tagging] Clarification on the role link in route relations
Dave F
davefoxfac63 at btinternet.com
Fri Jan 14 00:09:10 UTC 2022
I'll start with the conclusion:
The problem is in your software. Code needs to added to ignore any
relations members with link roles.
On 13/01/2022 19:49, Zeke Farwell wrote:
> On Thu, Jan 13, 2022 at 2:15 PM Dave F <davefoxfac63 at btinternet.com>
> wrote:
>
> I'm well aware of route relations, of all types, but what have
> these to do with 'destination:ref*' tags on /ways/?
>
> How does routing software, which "lacks support for the 'role'
> tag" of route relations "cause problems for any editor, QA tool,
> or data consumer"? It makes no logical sense. (quotes from Minh's
> original post)
>
>
> We're just trying to determine if there is a reasonable use case for
> the link role in a road route relation. The only reason
> destination:ref is part of the discussion is because the only use case
> we've been able to think of for the link role is already handled by
> destination:ref.
Already handled? How long has it been in existence? Before 'link' roles?
>
> <https://wiki.openstreetmap.org/wiki/Role:link>
> The wiki defines 'role=link'
> <https://wiki.openstreetmap.org/wiki/Role:link> as:
>
> Link roads (highway=*_link) from and to the route. See highway
> <https://wiki.openstreetmap.org/wiki/Key:highway>=motorway_link
> <https://wiki.openstreetmap.org/wiki/Tag:highway%3Dmotorway_link>.
>
>
> Mappers are following this documentation and including on/off ramps in
> route relations with role=link. In most cases, an on ramp leading to
> a numbered route is generally not considered part of that route. To
> indicate which route it leads to, they way gets tagged with
> destination:ref.
You're using destination:ref to indicate what's written on a sign,
That's fine for adding niceties to routing software, but not for
defining directions of a route.relation. You've added destination:ref to
ways, suggesting it applies to all traffic using that way: 'To Dayton'
etc., but as I've said previously, *multiple* route relations can be
added to that way -
Not all of them will have Dayton as their destination.
A way that could have a link role in one route relation, indicating
access to a route relation, could be a middle section of another route
relation.
> So also including it in the route relation with the link role
> doesn't seem to add any information. Given this we're thinking it
> makes sense to remove this suggestion from the wiki.
It may not specifically to you in your specific case, but it doesn't
mean it irrelevant to others. If you literally ignore it, your problem
goes away.
DaveF
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