A two-way voice communication system shall be provided between the motor control point and all loading and unloading stations. A public address system reaching all points along the line is recommended.
34 Pa. Code § 7.450
This section cited in 34 Pa. Code § 7.441 (relating to definitions); 34 Pa. Code § 7.442 (relating to applicability); and 34 Pa. Code § 7.462 (relating to applicability).