[OSM-talk] Administrative boundaries along roads

[Anthony]

On Sun, Mar 21, 2010 at 11:40 PM, John Smith <deltafoxtrot256 at gmail.com>wrote:

> On 22 March 2010 13:31, Anthony <osm at inbox.org> wrote:
> > 1) How so?  In the worst case scenario you have an equal-sized mess.  Can
> > you give an example?
>
> Because you are trying to hit a moving target...
>

What does that mean?


> > 2) In most cases of road-realignment you generally *want* to move the
> > boundary at the same time you move the road.  If a road centerline and a
> > boundary line exactly coincide, it's almost surely because the boundary
> line
> > is *legally defined* as the road centerline.  (If some of the lines
> > coincided by pure coincidence, then you can and should use duplicate
> lines,
> > but even that doesn't stop you from using a boundary relation.)
>
> While I don't know about the US specifically, it has happened in
> Australia where boundaries that coincided with the centre of the road
> weren't moved when the roadway was realigned.
>

I'm sure it has happened in the US as well.

On top of that you have boundaries of local governments change when
> state governments redefine the local government boundaries, you have
> boundaries of postcodes that change, are split or merged, road
> alignment doesn't mean the boundary moves with it.
>

Postcodes are a whole different story.  At least in the US (which is what
we're talking about in this thread, as the thread is about TIGER), postcodes
are not defined by boundaries in the first place.  They are defined as a set
of delivery points.  In any case, let's stick to the topic of TIGER
administrative boundaries.

Yes, these boundaries change.  And the roads change too.  And sometimes,
when the road changes the boundary does not.  On the other hand, sometimes,
when the road changes the boundary does.

Just because some boundaries coincide with the centreline, doesn't
> mean they are legally bound to the centreline...
>

True.  What's your point?
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