Based on my limited experience bike paths are far more dangerous than roadways. The person making the u-turn is responsible for making sure that making the turn won't interfere with other traffic. The other traffic is responsible for realizing that the other people on the bike path are for the most part unaware that they aren't the only person on the path. I once came to a stop, after ringing my bell at least three times, behind a lady sideways on her bike in a path. The lady looked at me in surprise and then said to her friend, "I wondered what that ringing sound was!" Be careful out there.