Subject: Re: [Ecrit] Proposed requirement: split responsibility

From: Andrew Newton <[email-masked]>
Date: Mon, 23 May 2005 18:03:15 -0400

On May 23, 2005, at 3:10 PM, Brian Rosen wrote:
> We seem to be talking past one another.

I guess we can agree on this. :)

> But the bottom line is that routing data today is most often civic 
> address
> based.  Geo based routing is available in most places, applied mostly 
> to
> mobiles, and may have different routing than wireline.

I'm not arguing against this.

What I'm arguing against is an assumption being applied to our 
requirements that somehow mapping services are always going to fall 
cleanly across the civil address field boundaries (all those nice 
little elements in PIDF-LO that begin with "A").

As it so happens, my brother actually runs a PSAP and I get to bounce a 
lot of these ideas off of him.  His big comment regarding this notion 
was that politicians usually don't take into consideration which PSAP 
answers the phone when they rename a street.

-andy

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From: "Brian Rosen" <[email-masked]>
Date: Mon, 23 May 2005 22:51:04 -0400

The following applies to North America:

Look at it this way: While a political boundary can in fact cut across a
building (I know of a warehouse that has the front door in one county, and
the back door in another), for responder purposes, the address of the
building determines which PSAP responds to it.  

Mapping, at least today, always falls cleanly on a civil address field.

In fact, while you CAN get a polygon that is as accurate as the civil
address, in fact, in the cases I know about, the available polygons are not
as accurate as the civil address boundary.

Politicians cause all kinds of silly address analomies all the time.
The way they are dealt with now is that the PSAP issues a change to the
MSAG, which is the civil address database.  At the present time, there is no
organized way to get that change into the polygons, but presumably we'll be
asking them to do that.

Brian

> -----Original Message-----
> From: Andrew Newton [mailto:[email-masked]]
> Sent: Monday, May 23, 2005 6:03 PM
> To: Brian Rosen
> Cc: [email-masked]; 'Ted Hardie'; 'Henning Schulzrinne'
> Subject: Re: [Ecrit] Proposed requirement: split responsibility
> 
>

---

From: Henning Schulzrinne <[email-masked]>
Date: Tue, 24 May 2005 06:43:44 -0400

I think we are indeed talking past each other. This thread started  
with the assumption that you're stating below, namely that more than  
one mapping server may handle subsets of the same civic hierarchy  
level, such as a city. The assumption here is that the mapping server  
"above" this level doesn't keep track which child mapping server has  
what street. (This makes sense since the authority operating each  
street-level mapping server will generally be responsible for adding  
new streets, changing street names, or extending house number ranges.  
In New Jersey at least, coordinating such changes across  
jurisdictions would probably involve creating a State Department in  
each hamlet.)

To avoid confusion, there was never a problem with having any number  
of PSAPs handled by the same mapping server, divided according to  
arbitrary algorithms. If necessary, you could have all house numbers  
divisible by 7 handled by the lucky PSAP and the rest by the unlucky  
one. Mapping servers operating on civic coordinates will always have  
the ability to have individual entries for each house number, and  
possibly even floor.

The same problem doesn't quite exist in the same form for geo  
addresses, as the mapping hierarchically above the split city would  
simply have two polygons, one pointing to mapping server A and the  
other to to B. Since these polygons just describe boundaries, they  
are not likely to change. Adding a subdivision adds streets or  
numbers, but doesn't change the communal boundary. (I realize that  
towns annex unincorporated areas, but that generally means that some  
other polygon, say, for the county sheriff, shrinks, so this always  
requires some coordination.)

Thus, while this problem can theoretically exist for geo boundaries,  
it seems far less likely.

In any event, I don't have any objections to having a general  
requirement, but I'd want to make sure that the motivation doesn't  
obscure the likely problem.

> As it so happens, my brother actually runs a PSAP and I get to  
> bounce a lot of these ideas off of him.  His big comment regarding  
> this notion was that politicians usually don't take into  
> consideration which PSAP answers the phone when they rename a street.
>
> -andy
>