Why is it important to apply hand brakes during an emergency brake test?

Applying hand brakes during an emergency brake test is vital because it ensures that the train has complete stopping capability. The hand brakes serve as an additional layer of safety, providing direct mechanical control over the train's movement independent of the train's air braking system. During a test, verifying that these hand brakes effectively engage ensures that in the event of an actual emergency, the train would have all available means to come to a complete stop and prevent potential accidents.

This aspect of the test is critical, as relying solely on the air brake system might not suffice if it were to fail or be compromised. Having confident knowledge that the hand brakes are operational and effective enhances overall safety for the train crew and passengers, as well as for rail infrastructure.