[Tagging] siphon underpass

Mark Wagner mark+osm at carnildo.com
Thu Jun 8 18:01:47 UTC 2017

On Thu, 8 Jun 2017 15:40:23 +0200
Volker Schmidt <voschix at 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=

The English term appears to be "siphon" (or "inverted siphon" if you're
being pedantic).  It's not always flat land, either: the Bacon Siphon[1]
carries the Columbia Basin Project's main irrigation canal across a
small canyon.


  [1]: http://digital.lib.uidaho.edu/cdm/ref/collection/crbproj/id/1039

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