[Tagging] Tags useful for rendering of roads in poor conditions

[Fernando Trebien]

Welcome, David. If you've just been advised about this discussion, you
may wish to read it from the start:
http://gis.19327.n5.nabble.com/Tags-useful-for-rendering-of-roads-in-poor-conditions-td5791303.html

Like you, I'm concerned about road safety. I'm concerned about making
the visual map better for visual routing. And I'm also concerned about
unaware users who have been classifying roads as highway=track simply
because they are unpaved (managing that in Brazil has been a bit
problematic). The latter has given us some headaches here in Brazil.

I'll try to summarise: I'm pretty much open to using either the
surface or the tracktype tag, I'm just trying to figure out which
approach is most popular for this purpose. Different people have
advertised either approach, and both have problems of their own. The
surface tag may range from very specific (say, paving_stones:30) to
very imprecise (simply unpaved), and there are many values to be
handled (but I just provided a reasonably comprehensive list). The
tracktype tag has fewer values but (as Matthijs pointed out) some less
obvious semantics that requires checking the wiki frequently. To make
tracktype popular with highways that are not highway=track, I believe
we'd need to request JOSM's developers to add a tracktype field to
many presets, so it's extra trouble.

Like Matthijs, I've been leaning towards a combined approach that
would take both tags into account, so that different OSM communities
can choose what they prefer. It's no doubt that tracktype=grade1 can
be considered "paved" (for rendering) and any other tracktypes can't.
But in the absence of that tag, we can then use the surface tag to
decide.

>From other discussions, I've learned that the tracktype tag appeared
originally in the German community and it was originally intended only
for combined use with highway=track. Then, in Anglophone countries it
was understood that "track" in tracktype could refer to many highway
types, as they are all types of "tracks" (in actual English, not in
OSM tag lingo).

Rendering details is not the purpose of this list, I believe we're
discussing which tags are more meaningful to end users for
establishing a clear separation between paved-like and unpaved-like
ways. Briefly mentioning: Malenki has suggested grainy rendering for
"unpaved" ways, and Matthijs, a dashed outline. I think Matthijs'
suggestion may display more clearly. Malenki has also suggested a red
outline for 4wd_only ways and a blue outline for ways that go through
water (ford=yes). The latter two make a lot of sense to me. I'm not
sure we're gonna push them along with the "unpaved" style, but I
wouldn't oppose them either. But again, visual style is not to be
discussed here; perhaps the "design" list is a better place for that.

On Wed, Jan 1, 2014 at 10:07 PM, David Bannon <dbannon at internode.on.net> wrote:
> Hello Fernando, I was just advised about this mailing list so have
> joined yet another ! (sigh...)
>
> Thanks for pushing this issue, my concern is that people's lives are
> potentially at risk here.
>
> While I am not really committed to using tracktype= as the trigger, on
> the Austrialian mailing list we had a long discussion about it and, more
> or less, concluded it was the best option from a poor set.
>
> The options were summarised on
> http://wiki.openstreetmap.org/wiki/User:Davo
>
> and in the Discussion section, you will see that I quoted some numbers,
> dating back to late 2012 showing that there are twice as many tracktype=
> tags used as surface=unpaved.  I think the biggest problem with surface=
> is that it has so many possible values.
>
> The original approved definition of tracktype made it clear it could be
> used where highway= other than 'track' and it is widely so used but I'd
> have to download all the data again to get fresh numbers on that.
>
> I wanted to extend tracktype= to three further values representing 4x4
> only roads. But could not get a committment from enough people to get a
> vote going.
>
> But, all that aside, the real need is to see unsealed roads rendered in
> such a way that people are warned and not put in danger. I would be
> happy to support and sensible trigger tag. Except, perhaps, smoothness=,
> I will not describe the pretty little road I live on as "horrible" !
>
> David
>



-- 
Fernando Trebien
+55 (51) 9962-5409

"The speed of computer chips doubles every 18 months." (Moore's law)
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