On Thu, Apr 19, 2018 at 10:37 AM, Jack Burke <burke...@gmail.com> wrote:
> Keep in mind that OSM apparently uses "compacted" to refer to macadamized > roads, which is a specific process for building roads. > > Maybe they wiki should be updated to say that roads with loose pieces of > gravel scattered around but a hardened underlying surface is compacted, not > gravel? > I don't quite grasp the categories on the Wiki. I know that there are a good many rural roads around here that are finished with crushed stone (typically ones that would go through a 1-2 cm sieve) and fine sand. I'm not aware of a binder to harden the surface - certainly asphalt is not used. The local soil is limy enough that it could be that Mother Nature provides an adequate binder Herself, or it could be that the surface is simply traditional angled-stone macadam. Certainly it would not support high-volume traffic. It's dusty and the surface would fall apart under a heavy load. The advantage of the stuff is that a grader, roller and a couple of dump trucks can repair all the damage from frost heaves and rockslides much faster than the roadbuilding crew for a deep-bedded asphalt road. Many of these roads are open only seasonally - nominally they close 1 December-15 April, but in practice they'll stay open longer if there's no snow, open early if the conditions allow, or open late if Spring is late in arriving. I label it 'compacted', but the Wiki definitions don't seem to fit exactly. I've also tagged a couple of roads 'surface=shale'. They are places where the road is laid our by clearing the soil - often only a few cm thick - from native shale. The passage of traffic compacts the shale, providing a fine-grained surface, and the native shale is limy enough that it forms quite a good surface for driving. It does have a bad habit of forming fissures and sinkholes - a natural hazard of karst terrain. And there are a couple of roads that I've tagged 'surface=shells'. They're old roads in a fishing village, macadamized using crushed oyster shells as both aggregate and binder. Again, they provide a fair surface for traffic. Oh lordy, though, do they ever stink for a week or two after being laid down! The locals call all of these, 'dirt roads.' They are not.
_______________________________________________ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
