[Talk-us] Ferries

[stevea]

OK, Clifford, I take your point very well.  It may not be one-off, 
but when routing algorithms chase data in this way, we CAN say it 
comes close to "tagging for the algorithm" and is therefore to be 
discouraged.  But this might be considered a sharpening up of the 
data in a perfectly valid way which also supports routing algorithms.

How about a sane tagging scheme that will capture highway=ferry_link 
similar to highway=motorway_link?  That's off-the-cuff, but might be 
enough.  I think there was talk of this (or something similar) 
earlier, I'd have to go back in the threads and look.

Concomitantly, routing algorithms can and should pay attention to 
said tagging scheme.

SteveA
California


>On Thu, Nov 7, 2013 at 8:49 AM, stevea 
><<mailto:steveaOSM at softworkers.com>steveaOSM at softworkers.com> wrote:
>
>A very big +1 to this.  "Posing a challenge" to the construction of 
>an accurate routing algorithm is a poor excuse to propose rippling 
>through data changes for what would essentially be a one-off 
>convenience.  Greg Troxel's suggestion about 
>regular->service->regular and regular->service->ferry sounds 
>perfectly reasonable and can certainly be made to work for this 
>particular case.  Inside of a routing algorithm is exactly where 
>this sort of decision-making belongs, not by making data changes 
>that are more convenient for it.
>
>
>I disagree that we are making one-off change. What we are doing is 
>making the map more useful. When adding an access ramp to a motorway 
>we call it a motorway link. The waiting area for ferries is a 
>similar feature of a ferry route. It certainly isn't a service road 
>except in a broad sense. There was agreement to tag the 
>service=ferry to solve the problem. That wasn't my first choice but 
>it works.
>
>There is a push in OSM to include addresses. One of the big 
>advantages we gain is the ability to route from door to door. For 
>that we need ferry routing. Living in an area with one of the 
>largest ferry systems in the world[1], I appreciate efforts to solve 
>the problem. 
>
>[1] <http://en.wikipedia.org/wiki/Washington_State_Ferries>http://en.wikipedia.org/wiki/Washington_State_Ferries
>--
>
>Clifford
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