| Sound | Indication |
| o | Indicates a short sound. |
| - | Indicates a long sound.
|
| o | When stopped, the air brakes are applied and pressure is equalized. |
| oo | When stopped, locomotive will move forward, or acknowledgment of a hand signal to proceed. Also an answer to any signal not otherwise provided for. |
| ooo | When stopped, locomotive will back up, or acknowledgment of a hand signal to back up. |
| oooo | Request for a signal to be given or repeated if not understood. |
| ooo ooo | To notify track forces of fire on or near the right-of-way. To be repeated as often as necessary. |
| Successon of short sounds | Alarm for persons or animals on or near the track. |
| - o | Inspect the brake system for leaks or sticking brakes. |
| - ooo | Instructs flagman to protect rear of train. |
| - - o - | At every whistle post. At least one-quarter of a mile from every public crossing at grade, (except within limits as may be prescribed in special instructions) to be prolonged or repeated according to the speed of the movement until the crossing is fully occupied by the locomotive or cars. At frequent intervals when view is restricted by weather, curvature, or other conditions. |
| - | One mile from every flag stop indicated for their trains (except within limits as may be prescribed in special instructions). When a train or engine stops and a crew member is required, under Rule 41, paragraph(b) or Rule 101.2 to replace exploded torpedos. |
| - - - - | Flagman may return from West or South. |
| - - - - - | Flagman may return from East or North. |