When must crew members be prepared to stop regarding yellow-red flags?

The requirement for crew members to be prepared to stop when encountering yellow-red flags is designed to ensure safety in areas where there may be obstacles, work being conducted, or other hazards along the track. Specifically, crew members must be prepared to stop two miles beyond the yellow-red flag to provide adequate reaction time in case of an emergency or unexpected situation.

This distance allows crews to recognize the flags and take appropriate measures well in advance of reaching the potentially dangerous area. It ensures that they have enough time to assess the situation, slow down, or stop as needed, ultimately prioritizing safety on the tracks.

The correct answer emphasizes the proactive approach to safety that crew members must adopt when they see yellow-red flags, establishing a clear and practical distance that accounts for variables like train speed, track conditions, and visibility.