PURPOSE: To detect the approach of a train and speedily inform each operator about the approach of the train.

CONSTITUTION: A train l travels on a rail 2, and pillars 3-1, 3-2,... are arranged along the rail 2. On the pillars 3-1, 3-2,..., the on-pillar communication devices 4-1, 4-2,... are installed. Further, in the vicinity of the pillars 3-4, the portable receiving devices 5-1, 5-2, and 5-3 are positioned, and the operators take the portable receiving devices. For instance, when the train 1 travels in front of the on-pillar communication device 4-1, it transmits the approach of the train to the on-pillar communication device 4-4, and it transmits the approach of the train to the portable receiving devices 5-1, 5-2, and 5-3. In correspondence with this transmission, each portable receiving device 5-1, 5-2, 5-3 informs of the approach of the train to each operator.