Glossary of North American Railway Terms - D

D

• Dark Future: The current CSX paint scheme, also known as Yellow Nose 3 (YN3) or Gold Nose 1 (GN1).

• Dark Territory: Rail lines without signals.

• Darth Vader: The lens hood on a modern style of railroad signals, due to its visual resemblance to the helmet of Darth Vader from Star Wars.

• Deadhead: A passenger train that is travelling along a line but is not hauling passengers.

• Deathstar: The logo of the Illinois Central, which has the letter "i" inside a circle — based on a resemblance to the Death Star battle station in Star Wars.

• Diamond/Diamonds: Level crossing of two railroad tracks, at any angle from 15° to 90°.

• Dinky: Nickname given to small locomotives, particularly one running in industrial service and/or on narrow gauge tracks. Also, a small old-fashioned trolley.
• DPU: Distributed Power Unit. Locomotives at the end or in the middle of a train. Can either be manned or automatically controlled. Manned units are preferred to be called "helpers" by railfans and some railroad personnel.

• Draper-Taper: Nickname for certain Canadian locomotives that feature a full-width carbody with improved rear visibility, designed by William L. Draper, an employee of Canadian National Railway.

• Dynamics/dynamic braking: Regenerative braking in which the motors on the locomotive wheels generate electric power off of the momentum of the moving train, and this power is dissipated through resistor grids as heat.