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<div class="moz-cite-prefix">A couple of quick comments:<br>
<br>
There is a 4wd tag already in use - 4wd_only:yes|recommended
(with no being a pointless value) <a
href="http://wiki.openstreetmap.org/wiki/Tag:4wd_only%3Dyes">http://wiki.openstreetmap.org/wiki/Tag:4wd_only%3Dyes</a>
There's about 1000 instances of this tag in use in Australia.<br>
<br>
There was a proposal kicking around ages ago that was trying to
define some improved classification for unpaved roads (as unpaved
roads come in all sorts of varieties). I think the discussion got
pretty acrimonious and petty, but the thought was there. There are
roads I've been on where the surface would be OK for a normal car,
but the road is a series of sharp humps that would easily ground a
standard clearance vehicle.<br>
<br>
Seasonal closure is another area where I don't think the tagging
is complete/useful. The current tag is dry_weather_only=yes or
access=dry_weather_only, which is valid for any road that is
impassable in the wet due to surface condition or creek/river
crossings, but there are also tracks with explicit closures
(usually mid may to the first weekend in September or October) -
generally marked as 'SSC' in the VicMap series of maps. Don't have
a solution, but it something that might need working on as there
are a lot of SSC roads in Victoria and NSW <br>
<br>
Anyway, I'm all for improved tagging of dirt roads - it's my
favourite kind of mapping (usually cos it turns out to involve a
couple of days of camping and getting out into the bush<br>
<br>
Matt<br>
<br>
On 21/10/2012 12:03 PM, <a class="moz-txt-link-abbreviated" href="mailto:dbannon@internode.on.net">dbannon@internode.on.net</a> wrote:<br>
</div>
<blockquote
cite="mid:46217a218f3c33de582b3f9464710cf016d5a46e@webmail.internode.on.net"
type="cite"><br>
Hi Folks, recent I have been going over parts of OSM mapped some
time ago, following up on the infamous redaction. One thing that
jumps out at me is the inconsistent tagging of dirt roads. Even, I
must say, ones I have done myself but over a several year time
span.<br>
<br>
So I started to write some notes for myself and thought that maybe
I should add them to
<a class="moz-txt-link-freetext" href="http://wiki.openstreetmap.org/wiki/Australian_Roads_Tagging">http://wiki.openstreetmap.org/wiki/Australian_Roads_Tagging</a> I
don't think this is inconsistent with whats there now, just more
detailed. However, I do suggest that we need consider what the
rendering engines do with our data and I know that is a bit
naughty. But, in this case, I'd suggest to do otherwise is
negligent as it can have quite serious safety issues.<br>
<br>
So, would people like to comment on what I say here ? If we can
reach consensus, I'll graft some of it onto the OSM wiki.<br>
<br>
Unmade roads<br>
<br>
These are typically forestry and remote tracks, while they may
have been cut initially by a bulldozer they are not regularly
maintained and, importantly, are not domed and don't have good run
off gutters on the side. Such roads might or might not be single
lane, 4x4 only, might be dry weather etc. Be careful about
deciding on such restrictions, some people are often surprised at
how well a carefully driven conventional vehicle can use these
tracks. Highway=track will typically render to a dashed line.<br>
highway=track<br>
surface=unpaved<br>
lanes=[1; 2]<br>
4x4_only=[recommended; yes]<br>
source=survey<br>
<br>
Made but unsealed roads.<br>
<br>
Many rural roads fit here. There is no asphalt but the roads are
'made' and regularly maintained by, eg, the local council. These
roads often have a gravel base, always have dome shape, the middle
is somewhat higher than the sides and there is some sort of gutter
at the edge. The gutter will usually have "run offs" to drain
water away from the road. Such roads are almost never 4x4_only nor
dry weather only.<br>
highway=[unclassified; tertiary, secondary]<br>
surface=unpaved<br>
lanes=[1; 2]<br>
source=survey<br>
<br>
Use of the highway tag on dirt roads.<br>
<br>
While the selection of tags should not be defined by how current
rendering engines display, we cannot ignore the final outcome. In
Australia, a lot of dirt roads are quite important and sometimes
its necessary to compromise a little to achieve a useful result.
So the correct highway tag may be determined by a combination of
the purpose of the road and its condition. Tracks are often
rendered as dashed lines and most people would understand that
means some care may well be needed. Unclassified would indicate a
purely local function and is typically rendered as two thin black
lines with white between Tertiary roads usually are rendered with
two black lines and a coloured fill and many people (incorrectly)
interpret that as meaning a sealed road, so maybe mappers should
ensure they apply that tag only to dirt roads that are reasonably
well maintained. Secondary roads are shown as wider and a
different colour than tertiary and are definitely presented as
viable routes for people passing through the area. Some care needs
be exercised if a dirt road is to be classified as 'secondary'.<br>
<br>
<br>
Discussion<br>
<br>
Sometimes its hard to balance the description of a road against
its purpose. A good example might be the Plenty Highway. This road
is probably a track from a road condition perspective, rarely
maintained, sections of sand, corrugations and ruts. However, its
pretty long and a major link between some (admittedly small)
communities. As a 'track' it would not show up on a map until you
zoom in way past where you can get any idea of where it starts and
ends. At time of writing, its highway=primary (and, I might note,
incomplete), that's possibly dangerously misleading. Conventional
vehicles routinely use it but I'd probably give it a
4x4_only=recommended tag. However, none of the mainstream
rendering engines observe that tag, it is no real protection for a
visiting tourist.<br>
<br>
Similarly, even on the east coast, its not unusual to see dirt
roads defined as 'tertiary' or even 'secondary'. Thats probably
quite correct from a purpose view but a lot of (especially city
based) drivers get quite nervous when they find themselves on a
dirt road. If they have got there by following a OSM map showing a
road with coloured fill, maybe they have a case ? Most printed
maps here in Australia show unsealed roads without a coloured
fill. <br>
<br>
And this does, of course, highlight the need to survey roads.<br>
<br>
David<br>
<br>
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</blockquote>
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