[zipzapp]

Aha, that makes it clear (Wiping away the sweat ;-)). Not the tree is wrong but the bridge. It's not at the alongation of the road, so it seems to be blocked a little bit by the tree. But if you set a convoy just at the elongarion of the road , it will cross the river without any problems (They are amphibious and also able to penetrate the bridge, not shure about the last) and the tree will not disturb it. That there is no road directly at the bridge doesn't matter, my programm also calculates missing roads ;-)