30 CFR § 57.14109 - Unguarded conveyors with adjacent travelways.
Unguarded conveyors next to travelways shall be equipped with -
(a) Emergency stop devices which are located so that a person falling on or against the conveyor can readily deactivate the conveyor drive motor; or
(b) Railings which -
(1) Are positioned to prevent persons from falling on or against the conveyor;
(2) Will be able to withstand the vibration, shock, and wear to which they will be subjected during normal operation; and
(3) Are constructed and maintained so that they will not create a hazard.