Thank you all for the explanations. I think that my issue might have to do with UK English usage. I would never call a road tunnel a "culvert", I typically only work and map in a rural setting and a culvert is only a passage way for water, and is only used at a road or path crossing.
While a ford is something shared by a road and a stream one is still under the other, but the rules for rendering assume that the road is underneath. In the OSM ford wiki <https://wiki.openstreetmap.org/wiki/Key:ford> one photograph shows the path on top of the ford using the stepping stones. The Wikipedia <https://en.wikipedia.org/wiki/Culvert>reference cited on the OSM culvert wiki <https://wiki.openstreetmap.org/wiki/Tag:tunnel=culvert> only shows stream examples. Therefore, why not have a rendering rule for culverts in the same way there is a rendering for a ford? This has been an interesting thought process and I'm probably just lazy not wanting to split a watercourse twice and add a tag to the way as opposed to snapping a road or watercourse node and adding a tag to the node. Keep mapping On Wed, Feb 28, 2018 at 5:11 PM, Dave Swarthout <daveswarth...@gmail.com> wrote: > >If 2 ways share a node, then they must be connected to each other. ie on > the same layer. So one can't be above/below the other. A road and a stream > crossing on the same layer is a ford. > >If you tag the shared node as a tunnel, then you don't know which way > goes through the tunnel. Does the stream go through a tunnel, or does the > road go through a tunnel, or both? > > >It is much more useful to map tunnels/bridges as a way. If you know there > is a tunnel, but don't know how long the tunnel is, you can estimate it. ie > based on the width of the road. You can add a note to say the exact > >length/position is estimated > > Excellent explanation. Agree totally. > > On Thu, Mar 1, 2018 at 7:48 AM, Craig Wallace <craigw84+...@gmail.com> > wrote: > >> On 2018-02-28 23:21, Vao Matua wrote: >> >>> François >>> >>> I don't have an example. I was trying to think of an example where >>> layer would be needed for a stream/road crossing. A pipe would probably be >>> a better example. >>> >>> Sorry to cause a distraction. >>> >>> My real question is "Why not allow tunnel=culvert to be a node?" >>> >>> Emmor >>> >> >> If 2 ways share a node, then they must be connected to each other. ie on >> the same layer. So one can't be above/below the other. A road and a stream >> crossing on the same layer is a ford. >> If you tag the shared node as a tunnel, then you don't know which way >> goes through the tunnel. Does the stream go through a tunnel, or does the >> road go through a tunnel, or both? >> >> It is much more useful to map tunnels/bridges as a way. If you know there >> is a tunnel, but don't know how long the tunnel is, you can estimate it. ie >> based on the width of the road. You can add a note to say the exact >> length/position is estimated. >> >> >> _______________________________________________ >> Tagging mailing list >> Tagging@openstreetmap.org >> https://lists.openstreetmap.org/listinfo/tagging >> > > > > -- > Dave Swarthout > Homer, Alaska > Chiang Mai, Thailand > Travel Blog at http://dswarthout.blogspot.com > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > >
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