Final answer:
Before changing ends at a terminal, the train operator must make a brake pipe reduction to ensure the brakes are fully released.
Step-by-step explanation:
In the context of train operations, a brake pipe reduction refers to the action of reducing the pressure in the brake pipe system of a train before changing ends at a terminal.
This reduction in pressure is necessary in order to ensure that the brakes on the train are fully released and the train is ready to move in the opposite direction.
By making a brake pipe reduction, the train operator ensures that the brakes are not inadvertently applied when the train starts moving again.