thanks for the detailed answer, quite interesdting, seems to be a unique solution, but sound a bit complicated, but if works fast, it's okay but how do you ensure avoidance of other level geometries?

I read yesterday a robotics based simple method what I want to try out, where a grid or node based database is needed, static obstacles and dynamic agents have a repulsive and the target an attractive field effect, they can be summed and weighted, and each agent examines 4 neighbouring grids in the cardinal direction, and sets a moving force, this way a natural acceleration, deceleration, and obstacle avoidance can be achieved, and agent turning also can be handled easily. to avoid stucking in balanced areas a base force can be applied to each agents. just an idea I thought to share, and maybe I was not totally exact.