Blocco automatico a correnti codificate (BACC or BAcc, automatic block with codified currents) is a signalling block system used in Italy on railway lines using 3 kV DC electrification.
The track circuits used to detect the presence of a train also transmit coded signals to the trains which are used for train protection and cab signaling. Train protection systems that use BAcc are RS4 Codici, RS9 Codici and SCMT.
The frequency of the modulating signal encodes the signal aspect:
modulation frequency of 50 or 83.3 Hz carrier
modulation frequency of 178 Hz carrier
code
meaning
(none)
(none)
AC (Assenza di Codice)
transmission failure, e.g. on a siding not equipped with the required track circuitry
75 / min
(none)
75
the next signal is at "stop" or the train is about to enter a dead-end track, a partially occupied track or a track with particular short braking distance
120 / min
(none)
120
the next signal displays a speed restriction (to 30 km/h, 60 km/h or 100 km/h)
120 / min
75 / min
120*
the next signal displays a speed restriction to 100 km/h
120 / min
120 / min
120**
the next signal displays a speed restriction to 130 km/h (this code is currently not being used)
180 / min
(none)
180
the next signal is at "proceed", but the signal after that is at "stop" or displays a speed restriction (this code is also being used to announce the end of the BACC-equipped line)
180 / min
75 / min
180*
the next signal is at "proceed", but the signal after that displays a speed restriction (to 100 km/h or 130 km/h), or the train is approaching a slow zone with a speed limit of 150 km/h or less
270 / min
(none)
270
proceed with a maximum speed of 180 km/h
270 / min
75 / min
270*
proceed with a maximum speed of 220 km/h
270 / min
120 / min
270**
proceed with a maximum speed of 250 km/h
While RS4 Codici is a simple cab signalling system that only requires the driver to acknowledge any change in the aspect of the next signal, SSB (On board sub system) RS9 equipment also continuously monitors the train speed and computes braking curves according to the train's length, mass, and braking ability.
RS4 Codici uses a single 50 Hz alternating current. All codes that do not use the 178 Hz carrier are used identically for both RS4 and RS9 Codici. Thus, RS9 is backward-compatible to RS4 Codici.
An alarm is sounded in the cab if the train exceeds the speed setpoint by more than 3 km/h. If the train exceeds the speed setpoint by more than 5 km/h or misses the designated stopping place, the system applies emergency brakes.
Referencesedit
January 21, 2024
blocco, automatico, correnti, codificate, bacc, bacc, automatic, block, with, codified, currents, signalling, block, system, used, italy, railway, lines, using, electrification, track, circuits, used, detect, presence, train, also, transmit, coded, signals, tr. Blocco automatico a correnti codificate BACC or BAcc automatic block with codified currents is a signalling block system used in Italy on railway lines using 3 kV DC electrification The track circuits used to detect the presence of a train also transmit coded signals to the trains which are used for train protection and cab signaling Train protection systems that use BAcc are RS4 Codici RS9 Codici and SCMT Codes editThe information is conveyed by superposition of two amplitude modulated alternating currents in the rails with a carrier frequency of 50 Hz and 178 Hz respectively Receiver coils in front of the first axle of a locomotive or control car are used to detect the signal The frequency of the modulating signal encodes the signal aspect modulation frequency of 50 or 83 3 Hz carrier modulation frequency of 178 Hz carrier code meaning none none AC Assenza di Codice transmission failure e g on a siding not equipped with the required track circuitry75 min none 75 the next signal is at stop or the train is about to enter a dead end track a partially occupied track or a track with particular short braking distance120 min none 120 the next signal displays a speed restriction to 30 km h 60 km h or 100 km h 120 min 75 min 120 the next signal displays a speed restriction to 100 km h120 min 120 min 120 the next signal displays a speed restriction to 130 km h this code is currently not being used 180 min none 180 the next signal is at proceed but the signal after that is at stop or displays a speed restriction this code is also being used to announce the end of the BACC equipped line 180 min 75 min 180 the next signal is at proceed but the signal after that displays a speed restriction to 100 km h or 130 km h or the train is approaching a slow zone with a speed limit of 150 km h or less270 min none 270 proceed with a maximum speed of 180 km h270 min 75 min 270 proceed with a maximum speed of 220 km h270 min 120 min 270 proceed with a maximum speed of 250 km hWhile RS4 Codici is a simple cab signalling system that only requires the driver to acknowledge any change in the aspect of the next signal SSB On board sub system RS9 equipment also continuously monitors the train speed and computes braking curves according to the train s length mass and braking ability RS4 Codici uses a single 50 Hz alternating current All codes that do not use the 178 Hz carrier are used identically for both RS4 and RS9 Codici Thus RS9 is backward compatible to RS4 Codici An alarm is sounded in the cab if the train exceeds the speed setpoint by more than 3 km h If the train exceeds the speed setpoint by more than 5 km h or misses the designated stopping place the system applies emergency brakes References edithttps web archive org web 20060506191231 http www segnalifs it it bl N barsc htm Retrieved from https en wikipedia org w index php title Blocco automatico a correnti codificate amp oldid 1176372480, wikipedia, wiki, book, books, library,
