[Talk-GB] OSM UK address project: tags

[Sarah Hoffmann]

Hi,

On Tue, Dec 21, 2021 at 04:03:13PM +0000, Rob Nickerson wrote:
> One of the challenges we have is making sure that the right part of the
> address is assigned to the right addr:* tag in OpenStreetMap. We have
> therefore been studying the address tags and how they are used in the UK.
> Suffice to say it is not straightforward and without its inconsistencies. I
> have therefore produced the following wiki page to help other mappers
> understand the soup of available tags and which are better / worse to use.
> 
> https://wiki.openstreetmap.org/wiki/Addresses_in_the_United_Kingdom
> 
> You will see on the page that one of the concepts we struggle with is when
> you need both a parent and child part of the local area to describe a
> complete address. In Royal Mail's language they use a "thoroughfare" and
> "dependent thoroughfare" whilst in OpenStreetMap we seem to have multiple
> tag options. For the OSM UK project we want to keep it simple and not
> bombard new mappers with the details of conflicting / inconsistent OSM
> tags. As such we plan to use addr:place (child) and addr:street (parent)
> for these parent and child relationships.

Please, don't use a addr:street/addr:place combination for this.

addr:place is meant to be used when the address does not reference a
street at all. (Frequently seen in small villages in continental
Europe which often don't have any street names at all.) This is clearly
not the case here. In fact you have two streets in the address.

There are currently two main uses where addr:street and addr:place
are used within the same address. A valid one is in the Czech Republic
where houses have two housenumbers, one that refers to the street
and one to a consecutive number in the village. So we have addr:street
refering to one, addr:place to the other number.

The most common use for the two tags together however is when addr:place
is wrongly used as a drop-in replacement for addr:suburb. Note that
even in the UK most cases of these two tags together are a case of
"should be addr:suburb". You can browse the Nominatim QA to
find examples:
https://nominatim.org/qa/#map=8.06/53.26/-0.64&layer=addr_place_and_street

Thus, the best way to handle such a situation from the side of a
data user is to ignore the addr:place tag altogether in such a situation
or put it _after_ the street. Your suggestion would mean that a special
treatment for the UK is required that puts it _before_ the street. (And
that works only after you have cleaned up the 50000 or so misuses of
addr:place).

The situation with the dependent thoroughfare is a unique thing as far
as I'm aware. There may be some countries that add the name of a
building complex to the address. But so far I have yet to see two
streets as an official part of the address.

So by all means, please invent a new tag instead of
redefining the meaning of an existing one. My advice in this case
would be: put the "thoroughfare" in the addr:street tag because it
always refers to a street as far as I understand. Then invent
something new for the optional "dependent thoroughfare".

But if you must go with the existing addr:parentstreet, it is still a
lot better than addr:place. At least it can be detected without
resorting to guessing.

Sarah