[Tagging] Tag ref on motorway_link

[Andrew Errington]

On Wed, Oct 24, 2012 at 10:31 AM, Richard Welty <rwelty at averillpark.net> wrote:
> On 10/23/12 9:15 PM, David ``Smith'' wrote:
>>
>> If a motorway link is part of a route (one needs to actually drive on the
>> link to continue on the route) then I put the ref for that route on the
>> link. Otherwise, no ref tag.
>>
> i agree.
>
> by convention, ref tags get rendered on the map and users of the map
> expect to see some sort of clear signage relating to the rendered content.
> this is why i don't put New York State Reference Route numbers in the
> ref tag, i put them in ref:unsigned which isn't rendered.

Isn't that simply tagging for the renderer?  And doesn't this just mean

"I put them in ref:unsigned which isn't rendered...

...yet.

or

...by this particular renderer.

If something is useful it should be tagged.  If it *is* tagged, we
should have a consensus on the tag's meaning and correct usage.  If it
can be easily derived from somewhere else, then IMHO it shouldn't be
tagged.

I think that a link road is not the motorway itself, and therefore
should not have a ref tag.  If you are driving, and you are on the
link road, are you on the motorway?  I say 'no', you are on a road
leading to the motorway (or from the motorway to another road).

I suppose you could programmatically determine the class of road and
know that if ref is present, and highway=motorway then it means 'we
are on the motorway'.  If ref is present and highway=motorway_link
then it means we are leaving or entering the motorway.  Actually,
having just re-read what I wrote it means we should only tag ref on
link roads leading *to* the motorway.

I suppose I am arguing both sides.  I still maintain that a little
redundancy is good, but if we can easily derive something then we
shouldn't tag it.  Otherwise we create a maintenance problem, and a
problem when one tag is updated but not its (redundant) counterpart.

Best wishes,

Andrew