Data model Dead Heading Deadman Detection Detonators Diagnostic data Diamond Crossing Diesel Locomotive Digital E-P Brake Control DIP Dispatching DMU Documentation Double-Heading Double-Ending? Double Slip Dow Down Line Dragging Detector Drain Cock Driver's Brake Valve Driver's Safety Device (DSD) Driving Trailer (DT) Driving Van Trailer (DVT) Dual Voltage Locomotive (Train) Dynamic Braking