Talk:Tag:surface=compacted

I think the high quality with scooter photo is a better match to fine_gravel Tonyf1 (talk) 19:45, 24 November 2022 (UTC)

The documentation for fine_gravel says to the opposite, that tag should only be used where bicycle tyres sink in. Rest assured, I bet that consumers (e.g. bikerouter) will for long into the future treat fine_gravel as you think what it stands for, even though ambiguous, because that is what it has been used for by the mapping community in vast numbers, at least when found on tracks or cycleways. Hungerburg (talk) 18:51, 6 April 2026 (UTC)

Regional meaning of “gravel”

The statement that such roads are “also called gravel in many parts of the world” seems too broad. This may apply in some regions (e.g. Australia, New Zealand, parts of North America), where “gravel road” can refer to compacted aggregate, but not universally. Should this be clarified or qualified with regional context? --julcnx (talk) 13:56, 2 April 2026 (UTC)

Definition mixes material and method

The current definition combines a specific aggregate mix (material) with compaction (method), but this combination is not clearly scoped. If both are not required, `surface=compacted` can be interpreted broadly and used for well-maintained unpaved roads regardless of material. For example, the second image on the page could be interpreted as compacted dirt rather than an aggregate surface.

This is problematic, as compaction alone does not capture the underlying material. A compacted gravel, dirt, or clay surface can behave very differently, especially in wet conditions.

Additionally, it is unclear how to tag roads where an aggregate mix is present but no clear mechanical compaction has occurred (e.g. recently graded or loose surfaces). In such cases, the surface may not exhibit the stability typically associated with `compacted`.

Should the definition clarify whether both aggregate composition and compaction are strictly required?

Native soil tracks graded and rolled without any imported aggregate can be visually indistinguishable from crusher run in photos. Since compaction is a process not a material, the wiki should document observable distinguishing factors. Without this, consistent field application remains difficult. julcnx (talk) 13:16, 5 April 2026 (UTC)

The photo with the pothole shows some pebbles in the hole, but the top surface could be silt or clay, a mixture not be seen there. (I'd be curious how that behaves in wet conditions.) Obviously the surface has been compacted, if by developers or by mere use, impossible to tell from the photo alone. If I remember correctly, fine_gravel once upon a time was defined as "a compacted base with a thin layer of fine gravel on top", so this photo would the show the same with a thin layer of silt on top? BTW: What does "limerock" mean? (I can translate it, but I never seen something on location.)

Personally, I'd say, that compacted describes the base layer and not the "thin top layer". In my area the image from the header shows a really good example. (From the colour, the material contains a lot of limestone.) It is very easy to see through the thin top layer of fine gravel. I'd say something OSM mappers capable of in large numbers. Hungerburg (talk) 19:12, 6 April 2026 (UTC)

On limerock: a regional US term for processed oolitic limestone used as road base. Your point about the base vs. wearing surface distinction is useful, but it highlights rather than resolves the ambiguity: in many rural or lower-income contexts there is no engineered base layer, just graded local soil or laterite, and some mappers reach for surface=compacted too. The wiki not documenting any observable distinguishing factors, visible aggregate through the surface, camber, drainage, is what allows such wide interpretation. julcnx (talk) 16:05, 9 April 2026 (UTC)

I'd say, drainage the most essential detail to make a compacted surface stay in good shape. Get water off the there by crowning e.g. or a bottom layer of gravel to let the water sink down. A compacted surface soaked with water looses firmness like an animal its winter-coat. I observe that especially when super heavy logging trucks on the tracks in early spring. Hungerburg (talk) 20:28, 14 April 2026 (UTC)

Link to tracktype=grade2 based on firmness

The page associates `surface=compacted` with `tracktype=grade2`, which is primarily implied by firmness (mostly solid), not material.

While a compacted aggregate surface typically fits `grade2`, other surfaces such as compacted clay, laterite, or natural soils can also meet the same firmness criteria.

This suggests that the link to `tracktype=grade2` reflects surface condition rather than material, and is therefore not specific to `surface=compacted`.

Should this relationship be clarified as non-specific and based on firmness only? --julcnx (talk) 13:56, 2 April 2026 (UTC)

It is possible that many mappers can only recognize compacted using the additional construction cues some use for tracktype=grade2 (camber, ditches, embankments). The photos used to illustrate this type all have most of these features, and also relatively good smoothness, so mappers may also be using that as a cue too. I've seen many mappers referring to roads with compacted surface as being usable even under heavy rain and resisting rain well (but this doesn't help much in arid areas). --Fernando Trebien (talk) 11:51, 6 April 2026 (UTC)

Interesting point. If mappers are relying on indirect construction cues — camber, ditches, smoothness, rain resistance — rather than material composition, that would further support documenting these factors explicitly, as they are currently implicit at best. julcnx (talk) 09:25, 7 April 2026 (UTC)

Reword first sentence

The first sentence describes compacted as if it was a material, not a recipe how to create a reliably firm surface in all weather. The rationale perhaps: Bring it in line with other surface types, e.g. asphalt or concrete. Which are mixtures as well, not to forget that. But certainly much more accepted in colloquial speech. But going to a dealer, they certainly can offer material the lends itself very well to compaction. First sentence says:

surface=compacted is a mixture of coarser (e.g., gravel typically 20 mm) and finer (e.g., sand) aggregate, compacted (with a roller)

This is wrong: The material mix must also contain particles finer than sand, very fine particles so to say, silt and clay that is. Hungerburg (talk) 19:26, 6 April 2026 (UTC)

Agreed, the current sentence is wrong in two ways: it frames compacted as a material rather than a surface outcome, and it omits the silt/clay fines that are structurally essential for binding under compaction. Without that fraction a gravel/sand mix stays loose regardless of roller passes. A more accurate opener might be: "surface=compacted is an unpaved surface made from a well-graded aggregate mix — combining coarse particles (e.g. gravel ~20 mm), sand, and fine particles (silt or clay) — that has been mechanically compacted to form a stable, hard-wearing surface with more grip and firmness than loose gravel." --julcnx (talk) 16:03, 9 April 2026 (UTC)

Thank you! Just started a poll in the forums, independently of this here, as I was not notified. The fines are essential for compaction to be even possible, at least in terms used in construction. Lets see what the experts there come up with. --Hungerburg (talk) 20:19, 14 April 2026 (UTC)

The water-bound macadam article on Wikipedia makes this precise: Edgeworth's method "filled the gaps between the surface stones with a mixture of stone dust and water." That stone dust (the very fine fraction) is what enables binding under compaction, which is exactly the nullanteil point. Worth citing in the revised first sentence as a historical grounding. julcnx (talk) 14:16, 4 May 2026 (UTC)

Natural hard surfaces: laterite, murram, caliche should not default to compacted

The current description defines surface=compacted as "a mixture of coarse, fine and very fine mineral aggregate, typically mechanically compacted." This correctly implies an engineered, graded mix where the coarse fraction creates an interlocked structure.

However, the wiki gives no guidance for a large and important class of surfaces that can appear identical to compacted in dry conditions:

• Laterite / murram (sub-Saharan Africa, Southeast Asia, tropical South America): iron-oxide-rich tropical soil; firm and dusty when dry; near-frictionless and then deeply plastic within minutes of first wetting. No coarse aggregate fraction. Covers approximately one third of Earth's continental land area.
• Caliche / calcrete (arid regions): calcium-carbonate-cemented natural surface; firm when dry; can behave unpredictably when wetted.
• Black cotton soil / Vertisol (parts of South Asia and East Africa): smectite-dominant clay; extremely expansive and plastic when wet.

These surfaces share firmness in dry conditions with compacted roads, but their wet-season behaviour is fundamentally different. Routing based on surface=compacted will systematically overestimate passability for large regions of Africa and Asia where these soils dominate unpaved roads.

Proposed addition (between the opening paragraph and the examples gallery):

Natural hard surfaces

Firm unpaved roads formed from native materials — such as laterite, murram, caliche, or calcrete — may appear similar to surface=compacted in dry conditions but represent distinct material types with different seasonal behaviour. Firmness alone is not sufficient to apply surface=compacted. Tag by material when identifiable:

• For lateritic soil roads (tropical/subtropical setting, red/orange, plastic when wet): use surface=laterite if locally confirmed (proposal pending), otherwise use surface=dirt or surface=ground
• For caliche hardpan: use surface=dirt or a locally established value
• Reserve surface=compacted for surfaces formed from a deliberately graded or mixed mineral aggregate

This addresses a confirmed documentation gap and would improve routing accuracy for significant parts of sub-Saharan Africa, Southeast Asia, and Latin America. --Julcnx (talk)