Over here in USAnia where the standard approach is to put up road signs for every sort of announcement, warning, regulation, etc., there are places where one sees "Primitive Road - No Warning Signs". In other words, since the right to have a drivers' license is thought by many to be about the 2.5th amendment to the Constitution, you need to be told that you are not about to be spoonfed.
In New Mexico there are two sorts of single carriageway roads, viz. those that traverse the scorching plains™ and those in the mountains. The latter have blind corners and frequent changes of gradient while the former lack the twisty bits but have plenty of dips and crests to trap the unwary, fill with flood water and provide cover for Billy the Kid. Thus both have frequent "no passing" zones. At the start of each and every such zone there is, on the left of the road, one of these:
P9230096 by
Mr Larrington, on Flickr
while on the right there is one of these:
P9230097 by
Mr Larrington, on Flickr
And at the end of the zone, one of these:
P9230098 by
Mr Larrington, on Flickr
These three, by the way, were no more than a hundred yards apart. The signs are quite large and made from aluminium. We have similarly-constructed signs to mark off the distances at Battle Mountain; had they not fallen off the back of Don Schroeder's then-employer we'd have had to stick with the ancient home-brewed wooden ones which never quite recovered from spending a Several of months in a shipping container half-full of snow-melt. Anyway, there must be untold thousands of these signs in New Mexico. Quite how they remain unstolen by the local
[“oiks” – The Invigilator] is a mystery worthy of Benedict Cucumberpatch.