What must employees on the leading engine be vigilant about?

Employees on the leading engine must be vigilant about signals affecting the movement of their train because signals are crucial for ensuring safety and proper operation. Signals provide important information regarding speed limits, track conditions, and potential hazards ahead. Being aware of signals allows the crew to react appropriately to changing conditions, maintain safe distances from other trains, and adhere to any restrictions that may be in place along the route. Understanding and responding to signals is a fundamental responsibility for the crew to prevent accidents and ensure the safety of operations.

While weather conditions, communication from the dispatcher, and maintenance status of the tracks are also important aspects of safe train operation, the direct responsibility of the crew on the leading engine focuses more specifically on understanding and responding to signals that directly affect their train's movement.