Thanks for the response, Robert. The information and graphics are useful. I will go ahead and give this a shot, but I think that it might be easier due to the nature of the barriers (multiple floors, multiple buildings) to assign the affected edges with an attribute that can be used as a restriction. This is a helpful workaround if just one building, or one level of barriers, but unfortunately I feel the query would be so lengthy it might be more work that it's worth. Still going to try it out though.
Thanks for your continued help on this, we have been making progress.