Probably not a railroad grade, much too steep (and my mapbook has it listed as a road, they usually call decommissioned rail lines trails). The bridges had to be solid enough for trains, though, with how heavy the old off-highway logging equipment was. I'll try to get some photos of equipment next time I'm out.
As for the ditch- Probably about 2' deep where I was, the rear tire is hanging all the way out of the fender in this photo.
