Rule 99(F). When an employee alone finds track or bridge unsafe for trains at normal speed, he must immediately place a red flag by day, or a red light by night, between the rails of the track, or to the right of the track as viewed from an approaching train, in both directions one-fourth mile from the point to be protected. After the red signals are placed, he must go in the direction from which the first train is expected. One mile from the red signal, he must place two torpedoes on the rail not less than 150 feet apart. Continuing back two miles from the red signal he must place two torpedoes on the rail not less than 150 feet apart. He must then place torpedoes in the same manner in the opposite direction. Where there are two or more main tracks, signals must be place in both directions on all tracks affected. After the signals have been placed, flagman must return to the point of obstruction and remain until relieved by another flagman, except that it a train approaches, he must go toward it and flag it with hand signals.
Union Pacific Railroad Company. Operating Rules Effective May 1, 1972.