[Tagging] Additional detail of Levee mapping via embankments

Martin Koppenhoefer dieterdreist at gmail.com
Mon Nov 11 09:15:09 UTC 2019

Am Mo., 11. Nov. 2019 um 07:27 Uhr schrieb John Willis via Tagging <
tagging at openstreetmap.org>:

> It seems I was (very) confused, possibly by misreading it several
> different times. I have mapped 40km of levees wrong, with an improper lower
> bounds line. I’ll have to fix it.
> I now understand that my embankment lines at the top are the (only) proper
> way to map the edge of the embankment.
I am interested in mapping the extent of the levee/embankments with some
> kind of outer/lower line, either as a single area or as 2 related ways for
> a levee.

I agree we should have a way to map both limits, upper and lower, for all
kind of similar features, e.g. embankments, slopes, and similar. A relation
seems easier to evaluate and explicit, while a spatial query heuristic will
inevitably fail in some cases (lets not forget that we cannot assume that
OSM data is complete, having mapped the upper boundary of one embankment
and the lower of another, in proximity, and not having mapped the other
upper and lower boundaries, would not be considered an "error", just
incomplete data).

> it is interesting to me that a levee is a way that marks the “centerline",
> while the embankment maps the top edge of the slope - yet there is no
> documented way to map the *area* of the levees nor embankments. my “lower”
> embankment line (which is apparently very bad mapping) makes the extent of
> the embankments that make up a levee. while they sound simple, our levees
> are *covered with* parallel and intersecting roads.
some levees will have 5 parallel ways on them for different kinds of
> traffic. similar to man_made=bridge, showing the area used by a bridge is
> very useful.

maybe in case a road cuts through an embankment, you would have to map
several embankments (upper and lower boundaries) to represent it?

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