[Talk-GB] highway_authority_ref vs official_ref

[Mark Goodge]

On 09/04/2022 13:04, Nathan Case wrote:
> Great - just what I was missing. Thank you.
> 
> So - to check I've got this right - there is a desire to have a
> non-rendered reference tag because C (and U) references are rarely
> signed in the UK and may be re-used across different highway
> authorities? Makes sense.

Well... There's technically no such thing as a non-rendered tag, because 
any visual map of the data can render whatever its authors want it to. 
But yes, there are some tags that are generally not rendered unless 
there's a particular need for them to be. And one of those is 
official_ref=*.

> official_ref=* -- "not generally intended for public display or use".
> ~17k uses, global use (but limited). Currently the recommended tag
> for roads with no signed reference on the UK roads tagging wiki page
> (https://wiki.openstreetmap.org/wiki/Roads_in_the_United_Kingdom#Tagging_road_numbers)
>
>  unsigned_ref=* -- "...indicate the route number when the route
> number is not prominently signposted". ~183k uses, mostly Europe and
> North America.
> 
> highway_authority_ref=* -- seems essentially the same as both
> official_ref and unsigned_ref. ~42k uses, almost exclusively UK usage
> and very UK centred terminology.

It seems to me to be almost exactly the same as official_ref=*, given 
that in the UK, the highway authority reference is, by definition, the 
official reference.

That's not really the same, though, as unsigned_ref=*, as the latter is, 
according to the wiki, intended for use in cases where there is a 
public-facing reference number for a highway but it just happens to be 
missing (or sparsely signed) in practice. I don't think this is 
particularly relevant for the UK, as here, roads which are supposed to 
be signposted almost always are. I'm sure there are exceptions to this, 
probably in some remote rural areas, and if mappers are aware of any 
then this tag would be correct for those situations. But, as a rule of 
thumb, British roads that should be signed are signed, and therefore 
only the ref=* tag is necessary.

> Should we consider retiring highway_authority_ref and replacing with
> one of the more globally accepted tags?

I think there's a strong case for replacing all instances if 
highway_authority_ref=* with official_ref=*, given that, as far as I can 
tell, they mean exactly the same thing.

Mark