Found that a fair few villages in SW France have them - and of quite arbitrary design. Also completely
unavoidable, as the main "D" road passing through would be so equipped. However - more of the "plateau" type than the "short-sharp-sickening-crash" variety, thank Heavens!
The worst we encountered, however, were in Spain, in a small town called Llodio, just South of Bilbao. They were absolutely HUGE! Got some funny looks as we crept over them in the Roadster at <1 mph, listening for the unmistakable gut-wrenching scrape of aluminium on tarmac.
My advice - if you find yourself in desperate need of petrol after landing at Bilbao - don't go to Llodio! Petrol stations are astonishingly rare on the AP68 going south from Bilbao. I shall never again make the mistake of boarding the Ferry at Portsmouth with little or no fuel in the tank!
Fortunately - at the last check - I still have a sump