What is the primary reason for an operator to blow two distinct blasts on the whistle before entering an inspection shed?

The primary reason for an operator to blow two distinct blasts on the whistle before entering an inspection shed is to warn shop employees of the approaching train. This action serves as an important safety measure, alerting those who may be working in or around the inspection shed of the train's imminent arrival. It ensures that employees are aware and can take any necessary precautions to avoid accidents, as they may be in the vicinity of the tracks and need to be alerted to the presence of the train.

In contrast, signaling other trains of an upcoming stop does not require a specific whistle blast pattern and would typically involve different signals. Indicating that the train is operating at maximum speed is irrelevant in this scenario, as the focus is on safety rather than speed. Lastly, announcing a change in direction does not apply to this situation, as there is no indication that a directional change is taking place before entering the inspection shed.