[OSM-talk] [Talk-us] Addressing Question
frederik at remote.org
Thu Nov 12 22:41:53 GMT 2009
> On Thu, Nov 12, 2009 at 4:43 PM, andrzej zaborowski <balrogg at gmail.com> wrote:
>> Every single country has different addressing rules, it's not like
>> this particular scheme is special. That's why someone came up with a
>> tagging scheme that can express all or most of these rules
> They did? What scheme is that?
> My understanding of the history of the Karlsruhe Schema is that a
> bunch of people got together in Karlsruhe and came up with something
> that worked for them, explicitly stating that other people should
> develop something that works for them.
Speaking as one of that bunch of people; that ist correct. Of course
when developing the Karlsruhe Schema we hoped that our work would be
usable for others as well, but we were under no illusion that there are
places where it doesn't. (Not sure if I got the double negative right in
that sentence but you'll know what I mean.)
To be honest, at the time we thought that those places would be in the
"less developed" world, where sometimes houses are reported to have
addresses like "3rd house on left hand side after the tree that looks
like an elephant". We didn't think that the US would be so different as
to require their own schema.
If you do develop your own schema then I would ask you to consider to at
least adhere to the following basic idea that we used:
We said that in the long run, we expect every single house to be on the
map - either as a node or, more likely, as a building outline - and
carry its own number. Interpolation ranges, therefore, were meant to be
something easy for situations where you cannot be bothered to "do it
right". Our expectation is that in the long run, interpolation lines
will be obsolete.
An interpolation line still maps more or less what's on the ground - at
least the house numbers at both ends of the line will have been
surveyed. Many people in Germany even break their interpolation lines if
houses are missing in between, i.e. if a road has the house numbers 100,
102, 104, 108, 110, 112 they will create one interpolation line for
100-104 and one for 108-112.
Now if I understand your situation correctly, the only difference you
have is that your "interpolation lines" are one step more abstract; they
don't give a range of numbers of definitely existing addresses, but
instead give the range of valid numbers in the block concerned. So you
know that *if* there is a house #1300 it will be there (but it might not
exist at all).
My suggestion to this would be to use something like our interpolation
lines but give them a different name (e.g. instead of addr:interpolation
call it addr:range or something).
I would also strongly encourage you to use one such line on each side of
the road, instead of putting tags on the road itself. This makes it very
clear which side an address is on, better than any tags you can put on
the way, no matter how many "left/right" prefixes or suffixes you add to
those tags. This is one thing we discussed at length when setting up the
Karlsruhe schema; even here, many people advocated putting something
like "left:from=15, left:to=25, right:from=12, right:to=24" on the ways
but we'd have none of that. One of many reasons for that being that this
would interfere with ways being split or combined - this must be doubly
true for your schema: If you have to split a road in the middle of a
block because a speed limit starts there, how will you know which
theoretical house number would be at the split if the house hasn't even
been built yet?
Of course, and that's the "but", if such a schema leads to millions of
"address range" ways in places where no houses have been built, then
that's perhaps a bit confusing...
Thanks for listening.
Frederik Ramm ## eMail frederik at remote.org ## N49°00'09" E008°23'33"
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