[Talk-us] [OSM-talk] Addressing Question

[Frederik Ramm]

Hi,

Anthony wrote:
> 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

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"