[OSM-newbies] Small streams under minor tarmac roads

[James Ewen]

On Wed, Nov 11, 2009 at 12:42 PM, Nick Austin <nick.w.austin at gmail.com> wrote:

>> Cases 1 and 2 I would tag as a "culvert" because that's the technical
>> engineering term for them. So culvert=yes and level=-1 perhaps. This is
>> unlikely to render currently but only needs good support of tagging to see
>> that change.
>
> More people might use the tag if the wiki had some documentation for it.

It's pretty tough to not tag for the renderer, when the tags that are
listed are implemented by the renderers... I prefer to use tags that
are already defined and in common use rather than create a unique tag
that only I use, and will probably never be implemented by anyone
else, or the rendering engines.

I just drew in Oldman Creek which flows near my home last week.
http://www.openstreetmap.org/browse/way/44032449

I searched for culvert, and came up with only 4 hits where people were
talking about the term. The suggestion there was to tag as a tunnel
with layer=-1, which is what I did...
http://www.openstreetmap.org/browse/way/44033309

This renders in a reasonable manner in both Mapnik and Osmarender,
even though I know that the map data is supposed to be about the data,
and not the pretty picture.

Wikipedia defines a culvert as:

***
A culvert is a conduit used to enclose a flowing body of water. It may
be used to allow water to pass underneath a road, railway, or
embankment for example. Culverts can be made of many different
materials; steel, polyvinyl chloride (PVC) and concrete are the most
common. Formerly, construction of stone culverts was common.
***

It also references a citation about when a culvert becomes a bridge
under US definition. This definition is based on dimension, not
construction type.

***
When boxes or pipes are placed side-by-side to create a width of
greater than twenty feet, the culvert is defined as a bridge in the
United States.

http://en.wikipedia.org/wiki/Culvert
***
In the end, is it necessary to create a tag called culvert when tunnel
would appear to be the same basic definition? A stream or river is a
type of way, and the culvert is simply where the way runs underground.

***
The tunnel tag is used to map ways that runs through an underground passage.

http://wiki.openstreetmap.org/wiki/Key:tunnel
***

I see Randy just posted the same quotes from Wikipedia...

I still think that the tunnel tag covers it very well.

James
VE6SRV