[talk-au] dirt roads

Matt White mattwhite at iinet.com.au
Sun Oct 21 02:33:24 BST 2012

A couple of quick comments:

There is a 4wd tag already in use -  4wd_only:yes|recommended (with no 
being a pointless value) 
http://wiki.openstreetmap.org/wiki/Tag:4wd_only%3Dyes There's about 1000 
instances of this tag in use in Australia.

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.

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

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


On 21/10/2012 12:03 PM, dbannon at internode.on.net wrote:
> 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.
> So I started to write some notes for myself and thought that maybe I 
> should add them to 
> http://wiki.openstreetmap.org/wiki/Australian_Roads_Tagging  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.
> 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.
> Unmade roads
> 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.
> highway=track
> surface=unpaved
> lanes=[1; 2]
> 4x4_only=[recommended; yes]
> source=survey
> Made but unsealed roads.
> 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.
> highway=[unclassified; tertiary, secondary]
> surface=unpaved
> lanes=[1; 2]
> source=survey
> Use of the highway tag on dirt roads.
> 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'.
> Discussion
> 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.
> 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.
> And this does, of course, highlight the need to survey roads.
> David
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