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<p>Ian/all
<br>
<br>
I have been boldly marking paved and no-tag as asphalt,
causeways/fords/bridges as concrete (etc) as a result of examining
my own Mapillary imagery, sometimes dovetailing that with the DCS
data. These are not only regional highways, but backroads and most
of small towns.
<br>
<br>
I actually use the overpass query to help route plan, deliberately
checking those with no tag. The query also showed a number of
really strange errors, like only the ends of a rural road are
paved in real life, yet an entire road was paved (with a surface
tag) on OSM (West Wilcannia Rd from Menindee to Wilcannia for
example)
<br>
<br>
<a class="moz-txt-link-freetext"
href="https://www.openstreetmap.org/changeset/98337907">https://www.openstreetmap.org/changeset/98337907</a>
<br>
<br>
My Garmin GPS unit with an OSM based map tries to route me down
unpaved roads too.. Good surface information will give credibility
to OSM map data for general navigating.
<br>
<br>
I'll admit I have concerns that my surface tags for a paved
highway might be removed, so I welcome the change.
<br>
<br>
Bob
<br>
<br>
</p>
<div class="moz-cite-prefix">On 31/1/21 3:13 pm, Little Maps wrote:<br>
</div>
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<div>Hi folks, wondering if I can promote some discussion about
the section of the Aus tagging guidelines on adding surface
tags on roads. The text currently reads,</div>
<div><br>
</div>
“For most types of highway=* tags you don't need to specify the
surface=paved key/value pair as this is assumed, however make
sure you tag the road surface when it isn't a paved road.”<br>
<br>
This assumption is fine in large cities but is problematic in
rural and regional Australia. Can I suggest that it is replaced
by something like the following...<br>
<br>
"Surface tags should be added to roads wherever possible,
especially in regional areas. This advice differs from that on
the international key:surface wiki page, which states that,
'there is normally an assumption that the surface is
surface=paved unless otherwise stated.' However this assumption
is not valid across regional Australia as: (1) most roads,
including many major roads, are unpaved, and (2) mapping
intensity varies greatly among regions. Many roads that do not
have a surface tag may not have been examined by mappers. Adding
a surface tag will assist data users and help mappers to further
refine the regional road network."<br>
<br>
Long rationale (not for posting on the oz tagging guidelines
page)...<br>
<br>
<div>Surface tags have been added to relatively few rural roads
in many regions. Hence, the most prudent assumption is that
the absence of a surface tag means that the road surface has
not received attention from mappers. A default assumption that
any road without a surface tag is actually paved is most
likely wrong.</div>
<br>
Efficiency of mapping. Even if one has no interest in adding
tags to paved roads, the most efficient way to refine surface
tags is to interrogate untagged roads and tag them (e.g. by
using an overpass query that distinguishes untagged, paved and
unpaved roads, and variants thereof. Untagged roads can be
inspected and tagged as appropriate.) However, if mappers are
advised to not tag paved roads, then every paved road that is
untagged needs to be re-examined each time this is attempted.
This wastes a lot of effort.<br>
<br>
Some apps — especially routing and cycling apps (e.g. Osmand and
Komoot) — allow users to request paved or unpaved routes.
Regardless of the (unknown) assumptions that routers make about
road surfaces when creating routes, apps like Osmand present the
data back to users. The suggested route may be X% paved, Y%
unpaved and Z% unknown. In many regions, Unknown is the largest
category. This doesn’t inspire confidence in the route or
underlying data.<br>
<br>
Some assumptions about road surfaces can obviously be made. For
example, a primary road is more likely to be paved than an
unclassified road. However, most roads in rural areas are
tertiary or unclassified. Some are paved, many not; the ratio
varies unpredictably across regions and it is impossible to
predict which roads are paved unless they are tagged.<br>
<br>
Perhaps not surprisingly, the OSM wiki on key:surface gives
conflicting advice, beginning with the (European?) position that
“there is normally an assumption that the surface is
surface=paved unless otherwise stated” and later adding an
(American?) view that, “There are no default values for surface,
it is generally considered as OK and desirable to tag it
explicitly for all roads.” The latter approach seems most
appropriate in regional Australia.<br>
<br>
Adding surface tags to both paved and unpaved ways is the most
efficient method to: (1) allow data users to accurately predict
road conditions (this benefits users) and (2) improve the rate
at which unpaved roads can be reliably distinguished from paved
roads (this helps future mappers). They may be redundant on
motorways, trunk and primary roads, but these make up a tiny
proportion of roads in regional Australia and can all be coded
with a minimum of effort.<br>
<br>
Advising mappers to not add a meaningful tag would appear to be
counter to the goals of accurate tagging. Can we change our
advice to encourage mappers to add a surface tag wherever
possible?<br>
<br>
<div>Thanks for your time, I'm keen to hear your thoughts. Best
wishes, Ian</div>
<div><br>
</div>
</div>
<br>
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