Given that the railbarge seems to have the tracks cross ways, would the object to the left not be the "transfer" tracks to the shore? Perhaps mounted to a pier or a moveable element (like a loading ramp for a ferry) to accomodate differing tidal heights.
The cars were rolled off the transfer tracks on to cross rails on the deck of the barge
What I have wondered every time that I have seen this picture is--how did they get the tracks even close to the same in the vertical? I think that having the whole platform with the land based rails mechanically movable up and down was beyond the mechanics of the day--so it must have been a floating arrangement Imagine the first heavy car on to the barge. Barge lists into dock. Now rail on barge is tilted, car is pushing barge away from dock, and making it more difficult to push the car further on to the barge. Whole thing looks very top-heavy. And what are you going to pull it with? While there were paddle wheel steamers during the war, I think that most were commandeered and outfitted with guns for military use.
Some one in the upper ranks had a wet dream. Bet that that was the only barge load that they ever tried
A neat picture--have always liked it.
____________________ Fix it again, Mr Gates--it still works!"
As you say, 'the angle of the dangle' would initially be severe as each car moved onto the leeboard edge -- they must have used tail & main winches from the outboard side, or a damn good nudge from a loco. Why didn't they do it conventionally by running onto the barges bow to stern rather than cross-beam ?.