> On Jun 8, 2017, at 6:40 AM, Volker Schmidt <vosc...@gmail.com> wrote:
>
> I am looking into how to tag a frequent feature in my area, i.e. a siphon
> underpass, known in Italian as "botte a sifone" or "botte sifone" and in
> French as "pont siphon". This is a non.connecting waterway crossing where the
> lower waterway passes through a U-shaped siphon. The bottom part of the U is
> a tunnel that is lower as the normal level of the waterway.
> Up to now I have mapped them as tunnel= yes, and more recently as
> tunnel=culvert, but they are so frequent, and different from a culvert, that
> I would like to start tagging them with tunnel=siphon_underpass.
> They are also used to pass non-navigable waterways under roads and other
> obstacles.
> There are hundreds or more in Northern Italy and I presume in other flat
> parts of the world where there are many artificial waterways. I remember to
> have seen them on drinking_water canals in California, but don't remember
> where.
>
> I could not find any tagging schemes for this in OSM, but I may have missed
> them in ignorance of the proper technical terms.
>
> A locally famous example dates from the 16. century: il ponte canale
> Montaigne:
> http://osm.org/go/0IA2uooQI?m= <http://osm.org/go/0IA2uooQI?m=>
FWIW, it sounds what is being described is not a siphon as I understand the
term. It might be called a “inverted siphon”. Which, as wikipedia notes, is not
really a siphon [1].
While there are specific cases where the average mapper might be able to
determine that the covered section of a waterway is an inverted siphon, it
seems to me that this won’t be possible in the general case. After all, the
feature is usually buried.
[1] https://en.wikipedia.org/wiki/Siphon#Inverted_siphon
_______________________________________________
Tagging mailing list
Tagging@openstreetmap.org
https://lists.openstreetmap.org/listinfo/tagging
