At what point must the functional capability of the ETD emergency valve be tested?

The functional capability of the ETD (Electronic Train Dynamics) emergency valve must be tested at the point of installation to ensure that it operates effectively when required. This initial test is crucial because it verifies that the valve is correctly integrated into the train's braking system and can function as intended in an emergency situation.

Testing at installation provides a baseline for performance and addresses any potential issues before the train enters service. If the functionality is not confirmed at this stage, it could lead to significant safety hazards in the future, especially under emergency conditions where reliable operation is essential for stopping the train promptly. Routine checks or maintenance, while important, do not substitute for this critical initial verification of the component's operability.