Aqueduct rendering bug?

T99 · 2011-02-03T08:05:53.000Z

I have been mapping local creeks and canals recently (there is no shortage of them in Sierra Nevada foothills and California central valley). I have run into some challenges tagging aqueducts. What I mean by “aqueducts” are sections of irrigation canals built on man-made structures above ground level; they can pass over valleys, roads and other waterways. Here are a some examples:

http://www.openstreetmap.org/?lat=38.8369596004486&lon=-121.181280612946&zoom=18

http://www.openstreetmap.org/?lat=38.8559550046921&lon=-121.164554357529&zoom=18

http://www.openstreetmap.org/?lat=38.8791292905807&lon=-121.132499277592&zoom=18

I have tagged them with waterway=stream, bridge=aqueduct and layer=1. Mapnik does not seem to render them at all. Is this a wrong combination of tags, or is the bug in Mapnik?

I have a related question about siphons (technically, “inverted siphons” http://en.wikipedia.org/wiki/Siphon#Inverted_siphon)). These are tunnels or pipelines that dip to a lower elevation but then return to (almost) the original elevation. The pressure of the incoming water pushes the outgoing water up the opposite slope; hence, the conduit has to be a closed pipeline. A siphon can lead a canal across the bottom of a valley or under a natural stream. A siphon may run below ground, on the ground, or above ground (my third example has a siphon running below the original canal level but above a natural creek in a small canyon). Is there a way to differentiate between a closed, pressurised siphon and a regular culvert?

wyo · 2011-02-03T09:44:18.000Z

T99:

I have tagged them with waterway=stream, bridge=aqueduct and layer=1. Mapnik does not seem to render them at all. Is this a wrong combination of tags, or is the bug in Mapnik?

Curious, I’ve no trouble with canals

http://www.openstreetmap.org/?lat=48.643824&lon=6.271302&zoom=18&layers=M

T99:

Is there a way to differentiate between a closed, pressurised siphon and a regular culvert?

I don’t think so. Do you really have to differentiate them? As far as they are underground (layer=-1) it shouldn’t matter much.

Wyo

Ldp · 2011-02-03T16:20:24.000Z

Please open a bug ticket against the ‘mapnik’ component on http://trac.openstreetmap.org/ and we can see about adding stream bridges.

T99 · 2011-02-03T18:55:09.000Z

Ldp:

Please open a bug ticket against the ‘mapnik’ component on http://trac.openstreetmap.org/ and we can see about adding stream bridges.

This seems to be the similar to bug ticket 3005; I added a comment there:

http://trac.openstreetmap.org/ticket/3005