[Talk-GB] Admin Boundaries and Combined Authorities

Sarah Hoffmann lonvia at denofr.de
Tue Jul 28 07:48:53 UTC 2020


I'm the one who caused this discussion by editing West Yorkshire. I was looking
into admin boundaries for Nominatim (the search engine) who uses them to
determine the place description or address of a place. As part of this I had
noticed a hole in the admin level 6 coverage and 'fixed' it.

I have to say that this discussion reflects a paradigm shift in the interpretation
of boundary=administrative that I find concerning. boundary=administrative used
to reflect the hierarchical structure of a country as viewed by popular use. That
is quite practical because it makes it possible to determine reasonable subdivisions
from the OSM data without having to know how exactly a country is governed.

Since a few months I notice more and more that people start to interpret
boundary=administrative in a literal sense and argue that all those where there is
no direct governmental function have to go away or retagged with something else.
This 'something else' is often locally chosen without any coordination with the
international community or any documentation what so ever (try finding out about
boundary=ceremonial in the wiki if you don't believe me). I fear that we
end up with a fragmentation in tagging that makes it seriously difficult to use the
data in a meaningful way.

Coming back to the issue at hand: the regions on admin level 5 may not exactly have
an administrative function but my impression is that they are in wide-spread
popular use. I don't visit the UK often but even I am aware of them. That's a
good reason to include them in the boundary=administrative hierarchy. Moving them
to some other tagging schema makes them practically invisible.

Mixing regions and CAs in admin_level=5 is not a good idea either because it
breaks the global assumption that the admin_levels create a proper hierarchy.
Same goes for admin_level=5.5. This would be really unexpected and likely just
ignored by most consumers.


On Tue, Jul 28, 2020 at 06:41:02AM +0100, Steve Doerr wrote:
> Could they perhaps be 5.5 to distinguish them from regions?
> Steve
> From: Brian Prangle [mailto:bprangle at gmail.com]
> I favour admin  level 5 too.
> On Sun, 26 Jul 2020 at 23:52, Colin Smale <colin.smale at xs4all.nl <mailto:colin.smale at xs4all.nl> > wrote:
> The LAs of which the CAs are composed are sometimes Metropolitan Boroughs with admin_level=8, and sometimes Unitary Authorities with admin_level=6. I am tending towards admin_level=5; this value is/was in use for the Regions, but they no longer have an admin function (if they ever had one) so I consider admin level 5 as "available" for use by Combined Authorities.
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