[Tagging] Culverts and Fords

[Vao Matua]

Thank you Ralph, I understand your perspective, but have to disagree a bit
(I'm not looking for a battle, however).

A ford is a stack of layers that are directly adjacent vertically, with the
road slightly below the stream/river.  In the dry season a ford is only a
road and only becomes a ford when a watercourse flows over the top of the
road.

A culvert is a part of of road construction, a culvert would not exist
without the road, but the culvert is utilized by the stream.  Personally I
have physically installed culverts in road profiles where there is no
watercourse.  If I try to add a culvert in JOSM without an additional tag I
get a validation warning.

Wouldn't a road/stream crossing without a culvert or bridge be called a dam?

Isn't a culvert similar in rendering to an embankment?  An embankment is a
tag applied to a road or railroad, but it is a level beneath the road or
railroad.  A culvert happens to be perpendicular or so to the road rather
than adjacent to it.

Part of this discussion also is a matter of scale.  At some rendering of a
map even a place like Paris would be displayed as a node.  In the same way
a culvert displayed as a node would be appropriate at certain zoom levels.

I think an easy solution is to make the rendering rule for culverts be a
layer below the road and allowed to be a node.

I think this is an interesting discussion and is helping me understand
different points of view, thanks.

Emmor

On Fri, Mar 2, 2018 at 12:39 AM, Ralph Aytoun <ralph.aytoun at ntlworld.com>
wrote:

> The real easy way to understand *culverts* and *fords* for OpenStreetMap
> is about the layers they are on and this dictates the nodes they use.
>
>
>
> For a  *ford* the stream/river is at the same level as the road
> (effectively *layer=0*) and therefore they are able to share a node.
>
>
>
> Because a culvert (*layer=-1*)  is not on the same level as the road but
> passes underneath so it cannot share a node with the road and therefore the
> culvert is attributed to the river/stream with a node either side of the
> road.
>
>
>
> With a *bridge* the road (*layer 1*)  is not on the same level with the
> stream/river so again cannot share a node and therefore the bridge is
> attributed to the road with a node at each end of the bridge.
>
>
>
> Hope this will be of help in understanding the problem.
>
>
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
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