Is circle a "completed" road in Kids of Carcassonne?
A road is also closed when it forms a complete loop.
  If a part of a closed road has a color that no
  player is using, nothing is played on that part.


http://riograndegames.com/uploads/Game/Game_313_gameRules.pdf

This is from the rules for Die Kinder von Carcassone. As this is German for "The Kids of Carcassone", I assume it is the same game.