I think this sketchup for the northwest arm would work quite well. It has all the major street connections that would be able to handle the traffic flow.
Another thing I find interesting is if this were ever done, and a 3rd bridge built from the 111 to the rail cut connector road, we would have a true ring highway covering Halifax and Dartmouth
Also, I wonder if south end residents would be opposed to a tunnel. Their main concern seems to be their boats getting under it, and maintaining the natural look of the area.