[Tagging] [tagging] Canoe route / nautical channels

Christoph Hormann osm at imagico.de
Tue Jul 3 08:25:30 UTC 2018

On Tuesday 03 July 2018, Multi Modaal wrote:
> [...]
> Summary:
> I would suggest using [waterway=canal] or [waterway=river] for
> routable lines across bodies of water despite the fact that you
> normally wouldn’t call them as such. This because of common current
> practice for routable networks and other practical reasons.

Note Multi Modaal is trying to push this idea of tagging for the router 
into the wiki as established use of waterway=canal (which is obviously 
not).  Here what i added there explaining why this is a very bad idea:

Such use of waterway=canal is in fundamental conflict with the main 
purpose and primary use of the tag to map artificial physical waterways 
and is therefore strongly discouraged. It can primarily be considered 
Tagging for the renderer to place labels and tagging for the router. 
The commonly used method for mapping boat routes with regular service 
is route=ferry. Routes used casually, non-regularly and with wide 
variation in geometry by private boats are not verifiable and should 
therefore not be mapped in OSM. 

I hope there will be community consensus not to abuse waterway=canal or 
other waterway tags this way and we can remove the whole paragraph 

On a general note and as a suggestion to mappers who might be irritated 
about how to deal with OSMs free form tagging system:

* inventing new tags so far not used and documented is fine - but you 
should document them.
* adding new uses to secondary tags (like using surface=* or usage=* on 
features it is so far not commonly used on) is also fine if it matches 
previous use in meaning.
* adding new uses to existing primary tags is highly sensitive and 
should usually be discussed first.  Creating a new tag is almost always 
a better idea.

Christoph Hormann

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