A very intriguing photograph showing an item of equipment at an unspecified dock. It is not a railway line as the item would be positioned vertically when in use, the metal structure resembling a railway track is, on closer inspection a ladder and the roman numerals and letter E painted on the structure suggest that the end closest to the camera is the lower end when in position. The heavy rope like strip around the structure is, I suggest, a seal so I would suggest that this is intended to form part of a barrier to water, perhaps when a lock gate has been removed and replaced by a coffer dam, a pair of these structures would help to seal the recess in the masonry which receives the gate when opened. I would be most interested if someone can supply the definitive answer, but the current heading is not very likely to encourage further examination.