29 CFR 1918.37: Barges.

(a) Walking shall be prohibited along the sides of covered lighters or barges with coamings or cargo more than five feet (1.52 m) high unless a three-foot (.91 m) clear walkway or a grab rail or taut handline is provided.

(b) Walking or working shall be prohibited on the decks of barges to be loaded unless the walking or working surfaces have been determined by visual inspection to be structurally sound and maintained properly. If, while discharging a barge, an unsound deck surface is discovered, work shall be discontinued and shall not be resumed until means have been taken to ensure a safe work surface.