46 CFR § 108.217
Guardrails and bulwarks
April 15, 2021
(a) Each unit must have guardrails or bulwarks along the edge of the bridge, of each deck, and of each deck opening.
(b) Each guardrail and bulwark must extend at least one meter (39.37 inches) above the deck except where this height may interfere with the normal operation of the unit, a lesser height may be approved.
(c) Removable guardrails may be installed where operating conditions warrant their use.