How is an operational ETVS system indicated?

An operational ETVS (Electronic Train Verification System) is indicated by the illumination of green lights. Green lights signify that the system is functioning correctly and operational, thereby providing a clear visual cue to personnel that the ETVS is ready for use and monitoring train activities as intended. In railway systems and signaling, green typically represents "go" or operational readiness, which aligns with the operational status of the ETVS.

The presence of red lights typically serves as a warning or a signal of something requiring attention, while flashing yellow lights usually indicate a cautionary state that may not authorize full operations. Thus, the illumination of green lights distinctly confirms that the system is operational and performing its designated functions without any issues.