Is tracktype=grade2 also for trails with large naturally occuring pieces of rock?

[bradrh]

That’s a good example of many roads in the western US. Tracktype is about firmness, & I’ve quit using tracktype for these types of roads since it’s very firm, but very rough. tracktype is not very useful for these types of roads since it doesn’t capture the nastiness of it. Smoothness is better as defined in the wiki. I’d tag it as surface=ground, smoothness=horrible or very_bad. It’s tough to determine from the pic how deep that erosion is, that would determine if its very_bad (high clearance), or horrible (4wd)

[Map_HeRo (Mikke)]

@rhhs

surface=rock is an ambiguous tag at the moment, because it seems to cover 2 cases:

1. “Big pieces of rock used to improve path quality” and
2. “exposed bare rock”

Maybe it would be best to deprecate surface=rock and replace it with surface=bare_rock for ways that pass through areas of natural=bare_rock (assuming that describes their surface well) and with surface=unhewn_stone which is like surface=unhewn_cobblestone (i.e. it is a kind of paving “used to improve path quality”) but with stones that are not rounded. Maybe an additional tag value is needed for surfaces mostly consisting of stones larger than track ballast (given as a limit for gravel), for instance for paths that go across areas tagged as natural=scree.

There was another topic recently dealing with surfaces made up of loose stone and I proposed to use surface=gravel for those as main tag and specify more details by subtags:

gravel = a surface more or less completey created by or covered with loose gravel of different size from 2 up to some 80 mm, either intentionally build like that (cheaper than compacted) or emerged out of deterioration of a former compacted surface due to missing service. Rough and shaking bike ride. Gravel can be naturally rounded material (natural gravel) or sharp edged (crushed stone). For more detailed tagging, use the appropriate subtags.

• gravel=natural_gravel (if it is definitely rounded material)
• gravel=lag_gravel or cobblestone (if it is rounded material with sizes bigger then some 60 mm)
• gravel=crushed_rock (if it is definitely sharp edged material)
• gravel=riprap (if it is sharp edged material with sizes bigger then some 60 mm)

Note that riprap does not specify a size range of the stones, it is used for very rough material generally. In the wiki the term “track ballast” is mentioned for rough size crushed rock. This material also does not have a general size specification but normally does not exceed 60 mm.

[Mateusz_Konieczny]

@rhhs

Maybe it would be best to deprecate surface=rock and replace it with surface=bare_rock for ways that pass through areas of natural=bare_rock (assuming that describes their surface well) and with surface=unhewn_stone which is like surface=unhewn_cobblestone (i.e. it is a kind of paving “used to improve path quality”) but with stones that are not rounded.

I like this idea.

Especially as per this thread surface=stone seems to be misused/redefined at least sometimes - and I see how someone may have reached this opinion.

@rhhs

Maybe an additional tag value is needed for surfaces mostly consisting of stones larger than track ballast (given as a limit for gravel), for instance for paths that go across areas tagged as natural=scree.

I have seen some minimal use of surface=scree

[Map_HeRo (Mikke)]

@Hungerburg

Maybe you have local knowledge, but the photo does not indicate bedrock just below the surface, to the opposite, to me it looks like quite some gravel all below.

Even without local knowledge one can see that this is a track with a firm structure which does not necessarily require a base of bedrock. One can see that the tracks in both sample pics have developed by erosion from a stony ground - soft parts, sand and small stones have been washed away and the bigger stones have accumulated. I would place any bet you can drive a heavy truck there even under wet weather conditions. To me this remains a track of grade 2 definitely.

@Hungerburg

A grade2 has to have at least a flat/crowned surface.

That is subject to surface/smoothness, not track type.

[Hungerburg (Asa Hundert)]

So I went to unroll the history of the tracktype key, starting from the original proposal: Reminds me of how roads in openstreetmap are categorized - by importance in the network, primary, secondary, etc.

In my local area, nearly two thirds of all roads are tracks. If that was similar in the area of the proposal author, some desire to distinguish may look plausible.

Later in history it became a measure for how well-maintained a track or minor road was perceived and later still, firmness was added, perhaps in a bet to have a so-called verifiable aspect in the mix.

Are we there yet to do away with maintainedness and make tracktype only map firmness? Meanwhile, I still give the track in the photo above a 4 on maintainedness, as long as this is still the documented meaning of the key.

PS: The local administration has OGD on tracks. They do not grade; Properties they collect: paved/unpaved (gravel/ground), suitability for tractor/lorry/lorry+trailer, minimal width, steepness, crowning, and how water gets removed.

From comparing known tracks with the one shown above, I’d say, its unpaved ground, tractor only, no water removal. Certainly, some heroes will drive their truck up there, they may even have an extra item for billing.

[dieterdreist]

I have seen some minimal use of surface=scree

this seems to be specific to situations in the mountains (natural=scree), surface should rather be independent of the location/context

[rhhs (Richard)]

Now that the discussion in this thread has stopped, I think it is time to draw some conclusions. I think 2 issues have appeared here:

1. There is disagreement of interpretation and thereby inconsistent mapping of the tracktype key. This seems to have a historic reason: the key was originally proposed to be a measure of quality of tracks, but later changed to a measure of the ratio of hard and soft materials in the surface and developed towards being a measure of track surface firmness. The wiki describing this has developed in this direction, but still contains references to the original idea. The smoothness key was developed later as another measure of surface quality.

2. A clear tag is missing to describe way surfaces consisting mostly of large stones of size between gravel (which according to the wiki is up to the size of track ballast) and bedrock, with the tag rock having 2 meanings according to the wiki.

I have some ideas about what to do about this, which I will post as a new topic in the coming days. Looking forward to more feedback here!

[SekeRob]

Seen big, inmovable rocks being placed on ways to block particular traffic. The rock(s) could be mapped with a tag maxwidth:physical to indicate what can pass, MTB, foot, trike. Add those and within 24 hours, GraphHopper will tell in the OSM routing function if bike, foot, motorcar can pass the obstackle points, albeit GH is a bit tight, as the other router simulators within OSM are more ‘understanding’.
Of course there’s the supplemental smoothness tag, of several, but how that/those weighs in with routing I’ve never dug in to understand.

edit:correct typo

[SomeoneElse (Andy Townsend)]

@SekeRob

Seen big, inmovable rocks being placed on ways to block particular traffic

“barrier=block” is the normal way of mapping those, I think?

[Mateusz_Konieczny]

With surface=ground tracktype=grade2 · streetcomplete/StreetComplete@f7cb570 · GitHub StreetComplete will no longer treat surface=ground tracktype=grade2 as an obvious mistake that clearly needs its surface data resurveyed.

Note that it is just committed and not yet released, that will happen in the next new release.