Can you do a U turn on a yellow line?

[FJRider]

... "If it is safe to do so" should go without saying for everything you do ...

Including traveling at the posted speed limit. "If it is safe to do so" is the bit often forgotten/ignored by most (if it suits at the time). The sign says I can ... therefore I will ...

[Hawk]

so long as you don't cross the center line but then once completed you are going the wrong way .......................
not a recommended, yellow lines normally mean limited visibly.