What speed must you maintain at MP 114 if a yellow flag is displayed at MP 112 and there is no track bulletin in effect?

Answer: B — 10 MPH until the rear of the train has passed a green flag

When a yellow flag is displayed, it signals a warning to the train crew, indicating that there may be a condition ahead that requires slower speeds. In the context of this situation, the yellow flag at MP 112 instructs the crew to reduce speed and to maintain a cautionary speed until they receive further signals or complete specific procedures. Maintaining a speed of 10 MPH is the appropriate response in this situation as it allows for enough control and reaction time should a hazard be encountered. This speed is typically a standard response to a yellow flag when no additional instructions or track bulletins are provided. The regulation is designed to ensure safety by allowing the train to respond effectively to any unforeseen circumstances while approaching the warning. The emphasis on maintaining that speed until the rear of the train has passed a green flag underscores the need for the entire train to clear the restricted area safely before normal operations can resume. This approach reflects the operational protocols for safely managing train movements in the presence of warning signals. Other choices suggest different speeds, but none align with the specific conditions set by the yellow flag and the absence of a track bulletin, which would require a cautious approach at a controlled speed.