In Australia, some States have a road classification system that designates high-class highways/freeways as A, major arterials between regional centres as B and interconnecting roads as C. There is another class of road under that represented on maps often as a light colour such as grey, but usually they are sealed, too.

I've used these large-scale maps a lot in recent years to plan my routes. The signposting usually is related to the classification on the map, so a signpost may point to a town and have C111 as the road number (in this case, a connecting road that is lightly travelled but without a shoulder). If you're lucky, as in Tasmania, you'll also get a kilometre distance to that town. B-road usually have shoulders, but that is not guaranteed; A-class roads always will have a shoulder, but the traffic will move at high speed and have a lot of heavy transport.

Ive done a lot of riding in Victoria and Tasmania with the system, and it really hasn't let me down. I can avoid the A-class roads unless I have to ride them (for example, from Oatlands to Campbell Town on the Midland Highway in Tasmania). In Victoria, the options are usually a bit broader, except for the highway that takes me from home into Melbourne -- that is a nightmare and there aren't other options of the same distance.