[talk-au] Tagging "boundary" roads with addr:*

[Michael James]

There is some conceptual misunderstandings with how the spatial data is stored by Government and how it is different to the way we store it in OSM

Government data does not define a road as a line like we do rather it is the space between property allotments, that space is not always even and the road as used by cars often is much smaller then the total area.

Checking my area, when a suburb boundary follows a road it is in the centre of the gap between the properties that are either side of the road and that centre line is not always the paved road that you see on the ground.

Michael


From: Dian Ågesson <me at diacritic.xyz>
Sent: Friday, 7 January 2022 9:29 PM
To: Andrew Hughes <ahhughes at gmail.com>
Cc: OSM Australian Talk List <talk-au at openstreetmap.org>
Subject: Re: [talk-au] Tagging "boundary" roads with addr:*


Hi Andrew,



There a few conceptual things I don't understand about how is_in would be implemented with regard to suburbs

I'm curious; if the border of a suburb is defined by a road; does the border change when the road is changed? If, for some reason, the boundary road was moved 10m north, does the suburbs grow/shrink accordingly? Is the suburb border an infinitely narrow line in the "centre" of the roadway, or does the road sit entirely within one suburb or another? What if a lanes are uneven?

If it is not bound to the roadway, and is instead "static" geometry, then you could have a situation where a road which is supposed to be the border is actually entirely misaligned with the legal border. Is_in doesn't cause these issues, but I think it may worsen individual situations by providing a misleading explanation about where a road actually is. I'd also be concerned about maintenance in growth areas where new suburbs are declared, etc.

Dian

On 2022-01-07 18:38, Andrew Hughes wrote:
Hi All,

Since I am only trying to define those that cannot be determined spatially, this sounds correct to me: https://wiki.openstreetmap.org/wiki/Key:is_in

Explanation: Yes, they do say that the use is discouraged, but that is purely on the basis of boundaries being used as spatial relationships. I'm looking at exactly when that is not possible. I wouldn't want to tag something that clearly has a spatial relationship (topologically correct) with a boundary. Then, there's not discussion aroune what to do when this happens, only that others still advocate its use for such a scenario.

For the record, an example of why this is needed....

We'll have a list of roads "Evergreen Terrace, Springfield" and we'll have some information about the road like "Cars from Shelbyville are not allowed". If we can't locate these road(s) in OSM because  the topology of the road/suburb is inaccurate - we can't map it. Thus, either the topology needs fixing (which I believe is impossible and I'm not going to bother talking about that) or the roads on the boundary can have a tag which is absolute and can be used preferentially (if desired).

Thoughts?

Cheers,
AH

On Thu, 6 Jan 2022 at 09:02, Graeme Fitzpatrick <graemefitz1 at gmail.com<mailto:graemefitz1 at gmail.com>> wrote:


On Wed, 5 Jan 2022 at 20:03, Ewen Hill <ewen.hill at gmail.com<mailto:ewen.hill at gmail.com>> wrote:
Hi Graeme and happy new year,
   How much can you datamine from a suburb:left , suburb:right ? I would suggest suburb polygons and street names only which would cover all eventualities and allow for the change in the suburb area without having to touch each road affected

I agree entirely & wouldn't use it myself, but was suggesting a possible option!

I'd leave it as Sandgate Road by itself, but with 436 Sandgate Road, Clayfield Qld 4011, & 475 Sandgate Road, Albion Qld 4010, tagged on the individual buildings themselves, as they currently are.

Thanks

Graeme
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