is there a method to close one direction of a taxiway segment?

Yes, there is. But it is not a switch or option or anything, but rather the key lies in the logic of your taxiway construction. Think of the AI aircraft as mice which always seek the shortest path to get from parking to the runway or from the runway to parking. Keeping that in mind, you can delete taxiways or cross taxiways without noding them together in order to funnel traffic down desired paths. By allowing or disallowing certain pathways, you can gain one-way taxiways or other effects. Of course it cannot work in all cases and is highly determined on airport layout. If you thought a rubik's cube was fun, these kinds of projects will be just as entertaining.

thank you,you gave me some things to think about. It is necessary to find out if the mice calculate the distance for all the way to the runway or are only short minded and think from node to node. At first I thought your way could not help because the distance from A to B is the same as B to A.But as aircraft leave the runway some way after the starting point, we can use this fact for driving the mice to different taxiways. Perhaps it is also necessary to work with overlays and closed runways.Anyway, you are right, it will be tricky.