Where must yellow flags be displayed to indicate a restricted area?

Displaying yellow flags two miles ahead of a restricted area is crucial for ensuring safe railway operations. This distance provides enough advance warning to train crews, allowing them time to reduce speed, be aware of potential hazards, and prepare for any restrictions that may apply when entering the area. Such proactive measures contribute to the overall safety and efficiency of rail operations.

The rationale for choosing this specific distance lies in the need to take into account various factors, such as train speed, braking distance, and the time it takes for crews to process a signal or flag's implications. By adhering to the standard of placing yellow flags two miles ahead, railroad companies are effectively reducing the likelihood of accidents and improving the management of restricted zones.

In contrast, the other options do not provide sufficient warning for approaching trains. Displaying flags one mile ahead, at the entrance, or immediately at the area does not allow adequate time for crews to react to any restrictions or changes in operating conditions that may affect their journey. Therefore, the two-mile requirement is not just a regulatory measure but a safety best practice essential for maintaining operational integrity on railroads.