Which signal is used by a signalman to indicate parking brakes should be applied?

• A. Crossing arms extended above his head
• B. Arms down, palms facing inwards, moving arms from extended position inwards
• C. Horizontally moving his hands, fingers extended, palms toward ground
• D. Raise arm and hand, with fingers extended, horizontally in front of body, then clench fist

Answer: (D)

The main idea being tested is how a signalman communicates braking actions through hand signals. The signal for applying the parking brakes is a two-part gesture: first raise the arm and hand, fingers extended, horizontally in front of the body, then finish by clenching the fist. This sequence is designed to be highly visible and unambiguous in a yard or road where crews need a clear, definitive cue to secure the brakes.

Why this is the best choice is that the initial raised, horizontal hand position draws attention and establishes the action direction, while the clenched fist signals completion and firmness of the action—namely, that the parking brakes should be applied. The other motions are used for different instructions or signals in the standard set and could be misinterpreted as something other than applying the parking brakes.