On Sun, Sep 21, 2014 at 11:05 PM, Tod Fitch <t...@fitchdesign.com> wrote:

> On Sep 21, 2014, at 7:34 AM, Pee Wee wrote:
> >
> > Well if an unpaved  forest path would get gravel or fine_gravel thrown
> on top of it I would consider this some sort of paving that could be
> classified as "paved". You apparently don't. No need to argue about that ,
> it only goes to show that the suggested tag would not work. ;-)
> >
> In my part of the world, I can't imagine anyone in the general public
> considering a gravel surfaced path or road as being "paved".
> >
> In my mind, a good tagging scheme should have two main goals:
> 1. To be easy for a novice or entry level OpenStreetLevel mapper to do.
> 2. Be easy for data consumers to digest for wide spread uses.
> Looking at the first, in many cases we fail miserably at this. Where to go
> for definitive information (wiki, taginfo, mail lists, which of a couple
> help forums, etc.)? But we also fail when we try to get too sophisticated
> with our tagging. Despite being actively discouraged, "paved=yes/no" is
> used. And two of the top values for "surface=*" are "paved" and "unpaved",
> clearly taggers find the concept of "is paved" versus "is not paved" a
> natural one. And I strongly suspect you would get a more consistent result
> from an arbitrary person trying to "map what you see" if you asked them to
> look at a road and determine if it was paved or not than if you asked them
> to specify the name of the surface material. This is particularly true if
> their survey consists in driving from point A to point B and then asked (or
> trying to edit data in OSM) what the road surface was on each section road
> they used. They can probably tell you which sections were "unpaved" and
> which were "paved" but not tell you where the surface changed from concrete
> to asphalt, etc.
> On the second point, looking on printed maps of many vintages and at
> several routing engines, I see a distinction between "paved" and "unpaved".
> But not, with the exception of maps for a pretty specialized small group of
> people like highway engineers, between various paving types. So I think the
> biggest use of the "surface=*" tag is to determine "paved=yes/no". Giving a
> multivalued field to data consumers that need a boolean value requires a
> translation of some sort. We should not be "(mis)tagging for the (broken)
> renderer", but fundamentally we are "tagging for easy use by a software
> based data consumer" and in many years of software engineering I've noticed
> that every time you build a need for a translation in a process you build
> in a place for an error to creep in. So while "a renderer/router is
> perfectly capable of deciding" there can be inconsistencies in that
> translation between one data consumer and another leading people to suspect
> that something is flawed in data source.
> From both of the above, it seems that having "paved=yes/no" with
> "surface=*" would make it easier for both OSM mappers and OSM data
> consumers.

I agree with this assessment. As one can see from this discussion, the
various surfaces that one might tag mean different things to different
people, even to the extent that Pee Wee would consider a gravel covered
path as being paved. For me and most people in the U.S., gravel means
unpaved. Even if a road surface is hard and compacted, if the surface is
not some sort of _manufacured material_ (concrete, asphalt, paving_stone)
it is still "unpaved". In my mapping in Thailand, much of which is by
necessity done using aerial imagery (Bing), I use surface=paved and
surface=unpaved quite a bit. If I know the particular type of pavement,
I'll use that instead. Although I might argue against adding yet another
tag to the ones already defined is a bad idea, having the more generic
paved=yes/no tag along with surface=* to further clarify and expand on that
makes sense to me.

That said, I know that reaching consensus on this topic is going to be
exceedingly difficult. The discussion about the smoothness tag points up
the difficulties: There are bicyclists and roller-blade skaters,
wheelchairs and race cars, all trying to use the same map data to determine
a best route. That is why we have mappers already using tags that don't
_officially_ exist. In OSM you can invent your own tags, and maybe that's
the best way??? Make a tag, use it for a while, and have the discussion
after the fact <g>


Dave Swarthout
Homer, Alaska
Chiang Mai, Thailand
Travel Blog at http://dswarthout.blogspot.com
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