Further study is required to determine the exent of that line ca. 1865, and you're just the man to do it. As I remember them, Federal reports stated that planking had been removed from the bridge, but the trestle itself remained intact. It took little time to replace the missing planks and cross the bridge.
Nothing that I recall suggested that rails were in place and the line in operation. I would like to know if that was true and where the bridge stood. Do you believe it stood along the current rail line from Brock's Gap to Helena, or nearby?