[Talk-GB] C roads again

[Robert Whittaker (OSM lists)]

On 12 August 2014 20:08, Philip Barnes <phil at trigpoint.me.uk> wrote:
> I propose that nothing is removed, but the ref tag for tertiary and
> unclassified is moved to official_ref. This will retain the data and
> allow OSM to be used by those who can make use of this data.
>
> I know we should not tag for the renderer, but I think its ok to give
> the renderer a clue as to which are displayed on signs and which aren't.

I guess I'm going to be in the minority, but I have to object to this
proposed change.

I don't really get what the problem is with showing the numbers on the
shields on the default map. People using the map will quickly realise
that they're not typically signed on the ground. Neither are quite a
few names for rural roads outside villages -- but I don't see anyone
saying we should replace the name=* tag with official_name=* as a
result. So perhaps someone could clarify why it is a problem for them
to be shown?

To the contrary I actually find being able to see the numbers on the
map incredibly useful. Two particular use cases:

1/ Official government notices about developments, road closures and
diversions typically use the C-numbers to refer to the roads. Having a
map style that displays them makes it much easier for the public to
interpret the notices. Without such a map it would be much more
difficult.

2/ In OSM mapping work, official documents for street names and Public
Rights of Way released under the Open Government Licence will often
refer to the C road numbers. Again having a map that shown them makes
life much easier.

When it comes to U-numbers for unclassified roads, I can see that they
usually add unnecessary clutter to the map. So while they may be
useful to see at times, I'd be in favour of them not being displayed
on the default style. But I think this is a renderer issue -- perhaps
someone should submit a ticket to have ref=* not rendered on
highway=unclassified if there is a name=* present.

Or perhaps it's the reference numbers' use in routers that is the
actual problem? I can understand this more, but I'd have thought that
any decent routers will need to be aware of a lot of local
conventions, so it's not too much to expect they should also
de-prioritise UK C-road and U-road numbers in road descriptions.

IMO, the ref=* tag should be used for the primary reference number of
the object, regardless of whether or not it's indicated on the ground.
Whether or not these numbers are displayed on the map as shields or
used to name roads in routers is a matter for the render or router. If
there's a need to state whether or not the reference number (or the
official name for that matter) of a road is displayed on the ground
(or indeed if something different is shown) then I'd prefer a
different tag is used for that. (For example the ref:signed=no"
suggested/used by Andy elsewhere in this thread.)

But I guess this view isn't going to be popular. So, if there is a
consensus to go ahead with the mechanical edit to move the numbers off
the ref key, then moving them to official_ref would seem like the
least-worst thing to do. (I would, however, like to see official_ref
used in the highway shields when ref=* is absent on highway=tertiary
and above, so that the useful C numbers can still be displayed on the
main map)

Robert.

-- 
Robert Whittaker