What action must be taken after successfully passing the signal displaying 'Z' or 'D'?

After successfully passing a signal displaying 'Z' or 'D', the appropriate action is to change back to CBTC MCS mode when it becomes available. This is critical because signals 'Z' and 'D' indicate certain operational conditions that require the train to operate under specific protocols until it is safe to revert to the standard mode of operation.

CBTC, or Communications-Based Train Control, is a system designed to improve the safety and efficiency of train operations. Once the conditions that prompted a change in operation (indicated by the signal) have been resolved, reverting back to CBTC MCS mode ensures that the train can operate using the enhanced features of this safety system.

Continuing at full speed, reporting events to the crew, or resetting the motor immediately would not be appropriate courses of action following the specified signals. These protocols are designed to prioritize safety and operational integrity, necessitating a return to the standard operational mode under the guidance of the signalling system.