Purpose of the Radio In-fill Unit is to transmit the message corresponding
to the Eurobalise® in advance with respect to the Eurobalise® placed at the
signal. This way, a train approaching a red signal can revoke braking as soon
as the signal clears without the necessity to actually see the signal
physically.
The In-fill message is transmitted via radio using GSM-R and Euroradio
safety protocols, as in ERTMS Level 2. The use of radio allows a continuous
in-fill coverage at unlimited distance from the signal.intro
