What action should be taken when hearing one long whistle from the tower?

When a long whistle from the tower is heard, it signifies a critical communication or warning for train operations. The correct course of action is to stop all movement immediately within interlocking limits. This is important for maintaining safety and ensuring that no train enters an area that may be unsafe or require immediate attention, such as an emergency situation or a signal change. Stopping allows for the assessment of the situation, ensuring that there are no hazards present before any further movement can be safely resumed.

While continuing movement, slowing down, or checking communications may seem like reasonable responses in less critical situations, they do not adequately address the immediate safety concerns that arise from the long whistle. In train operations, following precise signals and communications is crucial to avoid potential accidents and ensure the safety of personnel and equipment.