Please correct me if I'm wrong, after reading what you said, I think that the point that I was missing was this: - "tracktype" is the "degree of compaction" of the material (regardless of material) - "smoothness" is the "degree of irregularity" of the surface (for wheeled vehicles, also regardless of material) - "surface" more closely represents the material structure, usually regardless of other characteristics (with a few exceptions)
The surface (not the "surface tag") can be fluffy and regular (some of the dirt roads, beach sand, etc.), or hard and irregular (such as in a road full of potholes). Fluffy or hard, it can be made of sand, clay, earth, etc. and many of those would be collectively called "dirt". If this conclusion is correct: - these tags are significantly more orthogonal than I thought they were - this is worthy of several notes in the wiki - it should simplify a lot of decisions in applications (for me) - these values of "surface" almost always imply tracktype=grade1: compacted, paved, asphalt, concrete, concrete_lanes, concrete_plates, sett, cobblestone, paving_stones, grass paver - in case we find something apparently contradictory as surface=asphalt+tracktype=grade5 (meaning "loose asphalt", which is silly but possible), tracktype is probably more relevant to predict surface quality - other values of surface can have any tracktype - all values of surface can present any level of smoothness (so smoothness is completely independent, while tracktype and surface may be thought of overlapping for several values) The whole confusion surrounding these tags is that some surfaces are usually "highly compacted" (concrete, asphalt, paving stones, etc.). These would almost always get tracktype=grade1. Moreover, the description for tracktype includes references to surface types, and maybe it shouldn't (or maybe should just be phrased a little differently). In summary: - "tracktype tag"="surface:compaction" - "smoothness tag"="surface:regularity" - "surface tag"="surface:material_structure" On Sat, Mar 15, 2014 at 9:36 AM, johnw <jo...@mac.com> wrote: > > On Mar 15, 2014, at 12:50 PM, Fernando Trebien <fernando.treb...@gmail.com> > wrote: > > How surprisingly similar the landscape in this area is to the place > where I live in Brazil. > > > That's really pretty! > > Anyway, back to your place. I believe you'd call this a dirt road > leading into a private property: > https://www.google.com/maps/@32.704426,-116.720207,3a,75y,160.59h,81.43t/data=!3m4!1e1!3m2!1sH5Ez46TUHWIetR4uLSCy0Q!2e0 > > > Honestly, I would say this is more of a gravel surface, or at least it has a > strong amount of gravel in it. > > But you are exactly right - I would colloquially describe it as a dirt road. > > > > https://www.google.com/maps/@32.754457,-116.675043,3a,75y,244.08h,66.68t/data=!3m4!1e1!3m2!1sJhyTrxQnSp12qvq6uDJ_QA!2e0 > > is what I would say is dirt, grade 2 > > And here is a dirt grade 4 or 5. > > https://www.google.com/maps/@32.704654,-116.725304,3a,69.4y,194.94h,67.89t/data=!3m4!1e1!3m2!1shSHA3wkceuNcBDfUVBL9CQ!2e0 > > > > Would you describe this surface as "earth"? Or maybe "compacted"? > > I think "sand" would usually mean fluffy sand, such as in beach sand, > like here: > https://www.google.com/maps?ll=-29.347317,-49.729185&spn=0.014065,0.047979&t=m&z=15&layer=c&cbll=-29.347303,-49.729198&panoid=nxCzohwftvM2H6wO89EJng&cbp=11,182.99,,0,3.15 > > > That road looks really old! > > > Sand is hard, because a truly sand road is usually just river bottom, like > in a wadi (wash) or beach, because the road is usually defined by the > natural borders (the wadi's banks, shoreline, etc). I don't think there > could be many marked "dune" roads, they'd disappear before they were mapped. > but maybe my experience is limited. > > https://www.google.com/maps/@32.915195,-116.240605,3a,33.3y,14.3h,79.76t/data=!3m4!1e1!3m2!1s6SYOIDZphiH9EfbnOULxfw!2e0 > > you can see the white sand where the road starts from the turnout. you can > easily get stuck in it. > > > Here's a road in Brazil that probably fits the American definition of > "dirt": > > > Exactly. > > > However, the surface here is "compacted" according to official > sources. It's hard to tell visually, but it's possible that the > mixture has been compressed. > > > Compacted "what" is the question. Tephra? Decomposed Granite? gravel? A > mixture of clay, sand, gravel, and organic bits called "dirt" ? > > I assume almost any grade 1or 2 track is compacted - isn't that part of the > definition or grade 1 & 2? > > but a whole lot of grade 3/4/5 maybe was once compacted, now it's just > falling apart/grass growing in the center. > > Grade 3 from the wiki: > > " > Unpaved track; an even mixture of hard and soft materials. > " > > > This is what I believe would be described as "earth" but not > "compacted" (also from official sources): > > > > I wonder if you'd call this "dirt" too. ' > > > yea, that's a dirt road alight - not sand and not little stones. I'm not > sure, but that looks a lot like like DG - decomposed granite - similar to > the red around my aunt's area in Jamul. > > > The distinction is quite > relevant for calculation of routes: you can't travel as fast on earth > as can on compacted, and earth is much more likely to turn into sticky > mud that may get you bogged. > > > > > Finding a gravel road here was harder than I thought it would be. I > could only get this photo: > http://2.bp.blogspot.com/_8dyZBqNo6TI/TUv3KhRjRiI/AAAAAAAAAXs/jOA_pfv_IH0/s1600/tainhas+-+brita.jpg > > > That is some coarse gravel, like for a quarry road for big trucks or > something. > > Most of the road gravel here in Japan is about 1cm. it slowly sinks into the > volcanic tephra clay, and then they add more. and more and more and more. > > > It turns out that most preparations that include "some gravel" but > mostly "soil" here fit the definition of "compacted" quite closely. > > I think that "earth" and "soil" are similar enough to stay only with > "earth" - but I'm not a native speaker. > > I also wonder which names the British would give to each of these surfaces. > > > > A few of the British people I've heard responded have said that they don't > have "dirt" roads there, so they are having trouble naming these. But that > isn't true. > > > This looks a lot like a grade 3 dirt track in sheffield. A little gravel at > the intersection, but the track sure is dirt (look at that mud!). > > https://www.google.com/maps/@53.48623,-1.646717,3a,77y,292.61h,92.29t/data=!3m4!1e1!3m2!1sIeza8rGd6eybG9tBBgRMwg!2e0 > > > Grade 3 farming track. > https://www.google.com/maps/@53.480851,-1.621276,3a,75y,222.14h,71.75t/data=!3m4!1e1!3m2!1sOCVq7UW1AdoLCbgIloHlhA!2e0 > > Grade 3-4 track > https://www.google.com/maps/@51.064536,0.093548,3a,41.3y,350.72h,76.84t/data=!3m4!1e1!3m2!1sbJDev6_uegah7WelCu1fkA!2e0 > > Grade 3 dirt track > https://www.google.com/maps/@50.872787,0.514791,3a,75y,30.01h,68.59t/data=!3m4!1e1!3m2!1sIQaQzUZI-E1t7_2dIBzAvg!2e0 > > What do british people call this surface? > > I hope it can go somewhere this time =D. > > > Javbw > > > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > -- Fernando Trebien +55 (51) 9962-5409 "The speed of computer chips doubles every 18 months." (Moore's law) "The speed of software halves every 18 months." (Gates' law) _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
