How many whistle blows are required to move the train backward slowly?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (D)

Mine train whistle signals rely on fixed blast patterns to convey exact actions and speeds to everyone nearby. For moving a train backward slowly, the code uses a longer sequence of short blasts, chosen to be clearly distinct from signals for starting forward or stopping. That extra length makes the intention unambiguous in a noisy, active environment, giving workers time to clear the area and the locomotive room to reverse at a slow, controlled pace. Because this longer back-up pattern specifically communicates reverse motion at a slow pace, it’s the correct choice.