[Tagging] Waterway direction

[Anthony]

On Wed, Sep 1, 2010 at 4:09 PM, SomeoneElse <lists at mail.atownsend.org.uk> wrote:
>  On 01/09/2010 20:53, Anthony wrote:
>>
>> Can you pardon my laziness and tell me whether or not the water in
>> that part of the canal fills the entire tunnel.
>
> It doesn't - there's a narrow footpath to the side (presumably where boats
> were pulled along manually - the horses had to take the path over the top of
> the hill I think).
>
> However - imagine that such a waterway were being built now and there wasn't
> a requirement for any sort of towpath.  If it were still navigable but you
> could still get a boat down it would it still be a canal?  I'd say yes, but
> others may differ.

Yeah, sure, it's a canal.  When I asked "fills the entire tunnel", I
meant top to bottom.

I'd definitely say
http://1.bp.blogspot.com/_HWU3wX2cDLQ/SV94KdSeLFI/AAAAAAAAEzM/T--2L-kY7G0/s1600-h/inside_the_Subterranean_River_2.jpg
is a waterway (and an awesome picture too).

Maybe this is just a case where a common term (waterway) and an OSM
term (waterway) are going to differ.  But then, it'd be nice if it
would differ as little as possible.

And what is the definition going to be.  Anything that carries water?

I'd say if the water typically completely fills a closed conduit, it
shouldn't be called a waterway.  Alternatively, we shouldn't have
man_made=pipeline, type=drain.  Because having two ways to tag the
same thing sucks.

(While looking at this I also noticed we have barrier=ditch and
waterway=ditch.  That also sucks, unless there's some distinction
between the two.  Which is
http://wiki.openstreetmap.org/wiki/File:IMG_6784.JPG supposed to be?)