"Sleeping policemen" is idiomatic in the UK, too - sufficiently to
have
been used as the basis of a TV advert, I recall!
The ones in India are deep deep undercover I suppose, because they are
almost never painted or marked.
Lately I've been seeing how much russian I pick up by osmosis, using
pop music and internet memes as primary sources.
Today I saw an image labelled « лежачий
полицейский »; sounding it out, that's /lezhachiy
politseiskiy/. Sure enough; even though the picture was of a
policeman asleep, the usual connotation of that phrase is exactly
what we've been talking about.
-Dave