[Tagging] Bad tag: demolished=<date>: move to a) modify, b) strongly discourage

[Andrew Chadwick (lists)]

On 28 June 2013 11:29, Steve Bennett <stevagewp at gmail.com> wrote:
> On Fri, Jun 28, 2013 at 3:23 AM, Andrew Chadwick (lists)
> <a.t.chadwick+lists at gmail.com> wrote:
>
> Mmmm...not quite. You're driving home from work. The bridge you
> normally drive over has been demolished. I'd say that's pretty
> "physically relevant" to you right now. And tomorrow. And probably for
> a few weeks. Maybe months. That bridge that was demolished 6 years
> ago? Not so much. It's up to local mappers to decide when to remove
> the object altogether.

Do you want it to be unavailable to routing, and also not rendered? Me
too, but in that case it's simpler to just delete the object or do
something to any tags with understood meaning so they, er, stop
expressing something that's now untrue. Physical relevance problem
solved.

Sure, it's amusing to ponder whether we should retain object identity
for moves, like that of the "demolished" (in reality, carefully taken
down) and then "rebuilt" (in reality, historic granite stonework
cladding on a modern concrete core)
https://en.wikipedia.org/wiki/London_Bridge_(Lake_Havasu_City) , but
in general we don't do that. Real-world history is not generally
preserved in a database object's identity, particularly when materials
might be reused in different objects.

So perhaps naïvely, I think it's a perfectly valid approach to delete
your bridge object from the database and replace it with what it has
now become.

But you have me guessing. What meaning do you think it adds to an
object to say that it's now "demolished"? Do you mean to express its
new physical rubble-ness, or capture the feeling of absence of
something recently pulled down and new facts about how human beings
might refer to it? Either's verifiable, in a way (either look, or ask
someone), and either's a meaningful thing to put on a map, in a way.

(Talk about psychogeography though! /not-a-request-no-seriously)

Perhaps a big black X would be a cute rendering for the latter sort of
thing. Give a concrete (as it were) example, tell us more about why it
makes sense not to delete the object, but to tag it up specially as a
demolished-thing. Some good criteria for when one should *stop*
mapping it and delete the object would be good too.

Sure, surrounding areas change character when stuff gets demolished.
Since demolition doesn't happen in a vacuum - there's often barrier
hoarding erected for public safety - and since during demolition the
area has a definite steel-toecapped work-booted character, it should
probably get a landuse tag. landuse=construction with a phase
modifier, or its own landuse=* would suffice. But that's a different
concern than that of object identity.

-- 
Andrew Chadwick