A system so arranged that its operation will automatically result in the following: A full service application of the train brakes if, while operating under a speed restriction, the speed of the train exceeds the predetermined rate. The application will continue until the train is either brought to a stop or, under the control of the engineer, its speed is reduced to the predetermined rate.

• A. Speed Controlled Train
• B. Automatic Speed Control System
• C. Engine (ENG)
• D. Track Car

Answer: (B)

This question is about automatic safety control that enforces speed limits. When a train is under a speed restriction and it exceeds the preset speed, the system automatically applies the brakes in full service to bring the train back down. The braking continues until the train is stopped or the engineer reduces speed to the allowed rate. This behavior describes an Automatic Speed Control System, a safety device designed to intervene and prevent overspeed under restrictions. The other terms refer to components or generic phrases that do not describe this automatic braking intervention: the locomotive engine and a track maintenance vehicle are not automatic speed-control systems, and a vague “Speed Controlled Train” isn’t a standard designation for this automatic safety feature.