[Tagging] surface=ground/dirt/earth

Fernando Trebien fernando.trebien at gmail.com
Thu Mar 20 14:50:59 UTC 2014

In fact, the picture in this article does correspond to the
description of grade4: "Almost always an unpaved track prominently
with soil/sand/grass, but with some hard materials, or compressed
materials mixed in."

Perhaps what people worry about here is "how soft" the surface is.
There may be various degrees of "softness" to be measured. Could they
be measured without too much hassle? The picture seems to give me a
clue: the car is practically half-sunken in the ground. It kind of
reminds me of how smoothness=very_bad is defined: high_clearance.
However, the reason in the context of tracktype would be different: in
smoothness, high clearance is required because of the shape of the
surface. On tracktype, it would be required because the vehicle (heavy
as it is and with wheels of some particular contact area) would
otherwise sink that much into the ground. Lighter vehicles and those
with larger wheels (larger contact areas) would be less likely to
sink, even if smoothness is the same.

At the same time, if you also think of surface shape, it's hard to
argue it should be anything better than
smoothness=very_horrible/specialized_off_road_wheels ("tractor, ATV,
tanks, trial, Mountain bike and all kind of off-highway vehicles"). At
least (subjectively) I wouldn't expect it to be passable by anything
smaller than a tractor without imposing risks or severe difficulties.
So, if applications used both tags as "limiting factors", the driver
would stay safe as long as mappers applied both tags. Still, there may
be situations with near perfect smoothness and almost no
firmness/durability; an extreme situation would be quicksand.

David, I tried to search for images of the "Kennedy Development Rd" in
Queensland but none of the images I got would be tagged as
tracktype=grade5. Do you have any example or any similar picture for
what you've experienced? Or maybe a coordinate that we can have a peek
at on Street View (either Google's or OpenStreetView)?

On Thu, Mar 20, 2014 at 10:33 AM, Martin Koppenhoefer
<dieterdreist at gmail.com> wrote:
> 2014-03-20 12:42 GMT+01:00 Richard Z. <ricoz.osm at gmail.com>:
>> That means that the description of grade5 in the wiki should be fixed as
>> similar or worse than the road to Jakutsk:
>>    http://www.ssqq.com/ARCHIVE/vinlin27c.htm
> looking at those pictures it seems as if that's not even a track but a road.
> If it were a track or if you were to apply tracktype anyway to this, I do
> not see a reason why this cannot be e.g. grade4. It is obvious that bad
> weather (rain, but also snow and ice) can make a road unpassable.
> cheers,
> Martin
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Fernando Trebien
+55 (51) 9962-5409

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