So that's what they are! I have come across these markings a couple of times while driving, and found them quite distracting, as I had no idea what information

So that's what they are! I have come across these markings a couple of times while driving, and found them quite distracting, as I had no idea what information they were intended to convey, and no idea how I was supposed to respond to them. Both the idea that more information always improves safety, and that the meaning of symbols is always obvious, seem naive. I am all for measures that improve cyclists' safety, but presenting drivers with puzzles does not seem to be a good way to go about it.