ASFA (Automatic Braking and Signal Announcement)
The ASFA system (Spanish acronym for Automatic Braking and Signal Announcement) is an Automatic Train Protection (ATP) and onboard signal cab signalling system developed by Invensys Rail Dimetronic to help train drivers to carry out their tasks by anticipating the signal aspects in the cab, avoiding unsafe situations caused by poor visibility, confusion, excessive speed, and even human error.
The ASFA TBS gives the driver advance warning of the aspects of the signals that the train encounters along its route, as well as other circumstances that are important for the train’s movement. Two balises are installed before each signal in the direction of the train’s movement (see figure 1), a main balise and another balise 300 meters from that one on a horizontal level (infill balise).
The ASFA TBS is an individual ATP that acts at the points where the balises are located, carrying out a series of functions in the train in case it does not respond to the degree that is required by the balise indication.