[Tagging] "Feature Proposal - RFC - Sidewalk

Josh Doe josh at joshdoe.com
Tue Mar 22 14:39:00 GMT 2011

On Tue, Mar 22, 2011 at 6:32 AM, M∡rtin Koppenhoefer
<dieterdreist at gmail.com> wrote:
> 2011/3/21 David Paleino <dapal at debian.org>:
>> On Mon, 21 Mar 2011 21:12:55 +0100, M∡rtin Koppenhoefer wrote:
>>> 2011/3/21 David Paleino <dapal at debian.org>:
>>> To not be misunderstood: I prefer explicit sidewalks (=separate ways)
>>> as I wrote above. But you should not map them as if they were
>>> independent ways.
>> They aren't: have you checked my proposal? They're part of the same relation
>> (street, or associatedStreet).
> If you need a relation for every sidewalk, it is clear that you are
> redefining footway, because not interpreting this relation will lead
> to misunderstanding for all footways (they would be understood as
> independent ways and routing would work worse then with no sidewalk
> mapped at all).

Adding footway=sidewalk is not redefining highway=footway, just like
saying service=parking_aisle is not redefining highway=service, rather
it is a refinement.

Likewise, using relations are not redefining highway=footway;
relations (to associate sidewalks with an adjacent road) are not
required, but rather add information that routers can exploit to give
more detailed directions.

Both methods have advantages and disadvantages. If one wants both to
associate a sidewalk with a road, AND to be specific about crossings,
barriers, surface materials, width, etc, then it will get complicated
no matter which method you prefer. With one you have two adjacent
ways, but require a relation to associate them. With the other you
might have to break the road into many arbitrary separate ways to
account for changes in the sidewalk. Both methods require tools to
enable clear and efficient mapping.

And to be clear, I personally prefer mapping as separate ways, which
works especially well for my area in the suburbs, but I'm not so
concerned about creating relations right now. I can imagine it
wouldn't be difficult to write a tool which would generate candidate
sidewalk+road pairs based upon the geometry, which upon verification
would automatically create or modify relations associating them.


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