Trains from TD berth data; positions are berth order, not distance. Loops, crossovers and turnbacks learned from train movements (build_ladder_flow.php). Signals: ● danger · ●/◉ single/double yellow · ● green — danger is derived from live S-class bits (hold-out validated); yellows/green are inferred from the signal sequence. ○ position only. Data from Network Rail and Rail Data Marketplace. Berth geometry from OpenTrainTimes.