i was trying out some spines objects like fence and stuff and there no Collinson added to them. so you walk though the fence. but there a Collinson wall spline object. so you places your fence spline object then you have to place your Collison wall next spine to that. that so much work. dose making fence object soiled have performance impact to the game.
So the fences should have collision, they'll be something your not setting. Unless the fence is your own model then you will need to add collision to it