Hitech,
Just tested the river creation function of the path tool. Wish it was enabled and then many of the bridge objects and how short spanned they are makes a lot of sense. Still that leaves the question of how the narrowest widths would turn out in reality crossing the size of polygons the mesh is composed of. Or would the water in the river be an object that lays on top of the ground with properties to allow PTs and LVT to sail on it and stop GVs when they touch it? That would still require some forethought and prepping of the terrain a stream or river will run along.
It looked like the river tool would cut out a large block of stream creation time for me and all the bridges I want to incorporate into the new terrain I'm constructing. I hope someday you enable that function. For now, I've gotten used to doing it the Michelangelo method with -10 to -30 in the elevation tool and manually cleaning up the shore lines.