[Tagging] Layers (was Eruvs etc.)

[Kevin Kenny]

On Tue, Sep 6, 2022 at 5:51 PM Mike Thompson <miketho16 at gmail.com> wrote:

> But some nodes in the "highway layer" should be shared with the "boundary
> layer", such as when a highway enters into a different jurisdiction and
> gets a different name, max speed, etc. Also, in some cases the centerline
> of the highway is legally the boundary between two jurisdictions, and in
> that case all the nodes in the highway should be shared with the applicable
> boundary .
>

You have to be careful with that. Moving the highway will likely NOT move
the property lines that follow the boundary, and certainly will not do so
without compensating the landowner who's lost property.  When natural
features move, the law gets complicated, because accretion, erosion,
avulsion, reliction, and so on all are distinct cases in the law.

Example:   The boundaries around
https://www.openstreetmap.org/relation/7393864#map=16/42.8584/-74.2734 are
not sloppy or inconsiderate mapping.  The river changed course, The
boundaries did not.
You see the same problem writ large at
https://www.openstreetmap.org/#map=13/37.9236/-89.9175 - where the state
line follows the former course of the river. There's a town in Illinois on
the Missouri side of the river.

The New York City law that establishes the boundary between Manhattan and
Brooklyn defines it in terms of the bulkhead line of the East River.  It's
well established, though, that the law is to be interpreted as 'the
bulkhead line as it stood in 1898, when New York and Brooklyn
consolidated'  In particular, the construction of the Gowanus terminal in
1922 https://www.openstreetmap.org/#map=16/40.6921/-74.0061 did NOT move
the line between the boroughs. (I had to go in and fix that, because an
overzealous mapper 'cleaned it up' and conflated it with the current
shoreline.)

I try hard to patch up boundary inconsistencies using the best available
data - ideally by fieldwork.  https://www.openstreetmap.org/relation/6304865
is a case where I have two supposedly authoritative data sources that
simply disagree.  Because the error was unusually large for authoritative
sources (30 m or so), I actually climbed into that area - and found cairns
at both corners! I left the inconsistent boundaries as 'beyond my pay
grade." On the other hand, I made substantial adjustments to the town line
up on the ridge. In any case, few people - including the respective
landowners - care where the precise boundary is between the state land and
the New York City water supply land, and the conditions in those mountains
would make a better survey inordinately expensive and dangerous.

Often the explanation for messy and inconsistent boundaries is that we
inhabit a messy and inconsistent world, as hard it is for some mappers to
believe.


-- 
73 de ke9tv/2, Kevin
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