void release_blocks_begin(const BlockList::iterator &);
void release_blocks_end(const BlockList::iterator &);
void release_block(const BlockList::iterator &);
void release_blocks_begin(const BlockList::iterator &);
void release_blocks_end(const BlockList::iterator &);
void release_block(const BlockList::iterator &);
void block_reserved(Block &, const Train *);
void sensor_state_changed(Sensor &, Sensor::State);
void update_next_sensor(Sensor *);
void block_reserved(Block &, const Train *);
void sensor_state_changed(Sensor &, Sensor::State);
void update_next_sensor(Sensor *);