[OSM-talk] Path vs footway vs cycleway vs...

[Roy Wallace]

On Tue, Dec 1, 2009 at 8:16 AM, Tobias Knerr <osm at tobias-knerr.de> wrote:
> Roy Wallace wrote:
>>
>>> Routing software that is aware of the local laws of each country seems obvious.
>>
>> Um...what??? That will not write itself. Do you expect us to
>> successfully digitize and maintain a database of all laws of all
>> countries? In a wiki, even? That's ambitious! I'd prefer to stick to
>> mapping what's on the ground.
>
> If we map what's on the ground, then we create a map database containing
> "here is an oneway sign, over there is a cycleway sign". That's
> nice, but if I want to do routing with this, I need information such as
> "can I use way w in direction d with vehicle v?" - and in order to know
> this, I need another database that tells me what a sign means in that
> part of the world (for example: are pedestrians allowed to walk on ways
> with a cycleway sign?).
>
> If we don't want a traffic law database, then we need to tag the
> required information directly. But then mappers don't just map physical
> reality. They interpret the signs (and other information) using their -
> hopefully correct - knowledge of the laws.
>
> Both can work, but /someone/ has to do the transfer from reality to road
> network attributes - either software (using a traffic laws DB) or humans
> (mapping more than just what's on the ground).

Good points. You did find a flaw in my argument - that I was sort of
advocating exhaustive tagging as well as only mapping what's on the
ground. Funnily enough, I actually find both of these extremes
acceptable. But that's not the point...

The point I was making was that it should *not* be necessary to
*require* "a database of all laws of all countries" to know what
highway=cycleway means. There should be one definition that is
consistent for the whole world. For example, "this path is marked with
a sign with a bicycle symbol on it". If people also want to put in
exhaustive information inferred from a law book, I'd prefer they go
ahead and use "foot=no + source:foot=lawbook". If people prefer to
leave out the inferred information, and instead write routers with
country-specific defaults, that's cool, too.

But highway=cycleway tags in the OSM database should all mean the same thing.