[talk-au] Tagging dirt and 4x4 roads - new approach

David dbannon at internode.on.net
Sun Nov 25 05:48:20 GMT 2012

Hi Matt, thanks for your input. Firstly, let me say I don't think this is a good outcome, its just that its as good as we are going to get.

I am not that concerned about the measures being subjective, its simply not practicable or even possible to describe the things we are talking about any other way. Any unsealed road is subject to wide variations in its 'usability' depending on weather, time of year, council funding, recent use and I suggest thats a far greater source of error than any subjectivness. and people vary in their skills and willingness to risk damage.

I don't think we can just throw up our hands and say its too hard, we have to make an attempt. I have recently demonstrated we are unlikely to get a formal change through, we have to use what we have already.

Like you, I don't particularly like tracktype, its stops short of were we need to be but its not too bad. To quote "Tracktype is a measure of how well-maintained a track or other minor road is." - thats pretty good and what the average road user needs to know. The definitions are not great but we cn easily overload them and (he says wistfully) we could define additional levels.

I like 'smoothness' even less (and I don't use it), the idea behind it is good and the definitions fine but the labels or values and the key name itself are just plain silly. 

Extra tags for surface would be a mistake IMHO, suppose we have corrugations and soft sand in the same road. Most use of the surface tag is 'unpaved' and I think that makes sense. I am not sure the rest of the world would follow even if we established a good schema. 4wd_only has its problems but even allowing for that, its dissapointing. And one routing tool developer dismissed it as an "Australian only tag" to me. Sigh....

My view is that trying to list all the factors that make a 4x4 track challenging is futile, I am sure we could, between us, come up with twenty or more without trying. I prefer giving a "summary", the net effect, - thats what the user wants to know. If they see something that says 4x4 recommended, and they can apply that knowledge to their own situation.

I have driven a few tracks over the years but have never driven a stair case.  I do like your example ! next time I have some time I might load i into JOSM and see how its tagged !



Matt White <mattwhite at iinet.com.au> wrote:

>I missed most of this discussion - been away on holidays - so I'm 
>getting in a bit late
>Anyway, some thoughts:
>* Firstly, David, I appreciate the effort in trying to unify the 
>4wd/surface/tracktype tag set to make it a little more coherent
>* The track type and smoothness tags are in my opinion useless tags. 
>What kind of surface do I expect if the smoothness is "very bad" and the 
>tracktype of "grade4"? Both are very subjective, and the smoothness tag 
>in particular is a terrible set of options. The track type page even 
>says it is really only for rough classification.
>* The surface tag I can, in principle, get behind, although I think it 
>is missing a few values that would be useful in Australia. However...
>* Unpaved roads are difficult to really classify the surface in terms of 
>anything other than dirt/sand/rock. The surface state changes over time 
>from smooth immediately after grading, to possibly deep 
>ruts/corrugations/mud after rain and wear. In this case, my personal 
>opinion would be to use some sort of tag like surface condition (options 
>being something like: maintained | uneven | degraded | corrugated | 
>rocky | rutted | deep_rutted, but even those change immediately after 
>track maintenance), with perhaps a best/worst case tag or similar
>* One area of 4WD/dirt road tagging not discussed (unless I missed it) 
>was inclines. Some sections of the bush tracks in AU are very steep, and 
>the only way up then is in low range. Knowing that there are 
>particularly steep sections of a road visually on a map is also pretty 
>* Seasonal closures still don't seem to be cleanly supported (there's a 
>dry weather only tag, but that is both subjective, and different to 
>gated public roads that are closed between June and October)
>* Overall, it seems like Australia has both the special conditions 
>requiring some extensions to the current 4WD/dirt road mapping data and 
>the active mapping community to back it up. I don't see why we shouldn' 
>agree on a handful of tagging rules for the AU conditions on this list 
>and use them (assuming that they are well thought out etc). Document 
>them nicely so the rest of the world can take them up, and make the 
>rendering changes etc ourselves (how hard can a casing change be in the 
>renderer? If we can do it an submit it to the trac system...)
>On a slightly tangential note, I've even managed to find a paved road 
>with a legal access restriction to 4WD only vehicles... in Italy of all 
>places. Access to the lower part of the town of Torno on Lake Como (just 
>north of Como itself) is restricted to residents with a specific permit, 
>and to 4WD vehicles only. The reason for this is that about 120 metres 
>of the road (which ordinarily is pedestrian only) is steps (not huge 
>steps, but about 150 steps nevertheless). There were also width 
>restrictions - a Fiat Panda 4x4 would just squeeze between some of the 
>buildings provided you folded in the wing mirrors... (here's the road 
>- there's no street view, but there's a panoramio photo)
>On 24/11/2012 3:59 PM, David Bannon wrote:
>> OK, time I decided we don't really have any prospect of changing
>> approved tags to address the dirt road situation.
>> So I will push a model, sort of supported by the three votes recorded (!
>> ). It will use existing tags (approved and unapproved) and accept that
>> maps such as OSM's are unlikely to ever show the results. On the other
>> hand, perhaps external projects will make better use of the data ?
>> Li Xia, I believe you have plans to use this sort of data, might be good
>> idea to confirm this works for you. (I have answered your two off list
>> messages but wonder if you got my answers ?)
>> I will push the idea that -
>> * All unsealed roads should have a tracktype tag and a surface=unpaved
>> tag.
>> * 4wd roads should have a 4wd_only tag and a tracktype tag. Maybe even a
>> smoothness tag if you like.
>> * We will ask the mainstream renderers to observe the above tags.
>> * Routers will be advised to note above.
>> I have update the Australian Tagging Guidelines page and add some data
>> to discussion tab. Particularly some numbers about current usage. And
>> why tags starting with a digit are a bad idea.
>> David
>Talk-au mailing list
>Talk-au at openstreetmap.org
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