D yard East End signal: what governs all eastbound moves?

• A. Two signals govern eastbound moves
• B. Manual switch governs eastbound trains
• C. A blue flag indicates eastbound movement
• D. Only one signal (eastbound color light low home Hw) governs all eastbound moves

Answer: (D)

The movement going east in this yard is controlled by a single authority: the eastbound color-light at the low home position. This one signal provides the go/no-go for all eastbound moves, coordinating direction and preventing conflicting trains from entering the same area. Other devices don’t independently authorize eastbound trains—manual switches only change the path, not the authority, and a blue flag is a protection tool for work on track, not a routine movement signal. So the essential idea is that a single eastbound signal governs all eastbound movements.