RS4 Codici
Encyclopedia
RS4 Codici is a train protection system used in Italy
. The term is an abbreviation of Ripetizione Segnali a 4 codici (signal repetition system with 4 codes).
It is a simple cab signalling
system, displaying the aspect of the next (and, in some cases, the next but one) signal
. It helps the driver to reliably determine the aspect of the next signal even in poor visibility and at high velocities.
The information is conveyed via amplitude modulation
of a 50Hz
alternating current
in the rails. 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:
The driver must acknowledge a code change by pressing a button labeled RIC within 3 seconds, otherwise the system will apply emergency brakes.
As trains got faster and additional set of codes sent with a 178Hz carrier were added. The new system was backwards compatible with the old 4-code system as trains unable to receive the 178Hz codes would be relegated to a slower speed. The 5 additional codes are as follows.
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
. The term is an abbreviation of Ripetizione Segnali a 4 codici (signal repetition system with 4 codes).
It is a simple cab signalling
Cab signalling
Cab signalling is a railway safety system that communicates track status information to the cab, crew compartment or driver's compartment of a locomotive, railcar or multiple unit, where the train driver or engine driver can see the information....
system, displaying the aspect of the next (and, in some cases, the next but one) signal
Railway signal
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...
. It helps the driver to reliably determine the aspect of the next signal even in poor visibility and at high velocities.
The information is conveyed via amplitude modulation
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
of a 50Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
alternating current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
in the rails. Receiver coils in front of the first axle of a locomotive
Locomotive
A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco – "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine, first used in the early 19th...
or control car
Control car (rail)
A control car is a generic term for a non-powered railroad vehicle that can control operation of a train from the end opposite to the position of the locomotive...
are used to detect the signal.
The frequency of the modulating signal encodes the signal aspect:
| modulation frequency | code | meaning |
|---|---|---|
| (none) | Assenza di Codice | transmission failure, e.g. on a siding not equipped with the required track circuitry |
| 75 / min | Via Impedita | 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 | Riduzione di Velocita | the next signal displays a speed restriction (30 km/h, 60 km/h or 100 km/h) |
| 180 / min | Preavvisa | the next signal is at "proceed", but the signal after that is at "stop" or displays a speed restriction |
| 270 / min | Via Libera | proceed without restrictions |
The driver must acknowledge a code change by pressing a button labeled RIC within 3 seconds, otherwise the system will apply emergency brakes.
As trains got faster and additional set of codes sent with a 178Hz carrier were added. The new system was backwards compatible with the old 4-code system as trains unable to receive the 178Hz codes would be relegated to a slower speed. The 5 additional codes are as follows.
| 50Hz modulation frequency | 178Hz modulation frequency | code | meaning |
|---|---|---|---|
| 120 / min | 75 / min | Riduzione di Velocita 100 | the next signal displays a speed restriction of 100 km/h |
| 120 / min | 120 / min | Riduzione di Velocita 130 | the next signal displays a speed restriction of 130 km/h |
| 180 / min | 75 / min | Preavvisa 150 | the next signal is at "proceed", but requiring reduction in speed to 150 km/h |
| 270 / min | 75 / min | Via Libera 220 | proceed without restrictions at speed up to 220 km/h |
| 270 / min | 120 / min | Via Libera 250 | proceed without restrictions at speed up to 250 km/h |
See also
- Blocco Automatico a Correnti CodificateBlocco Automatico a Correnti CodificateBACC is a train protection system used in Italy on railway lines using 3kV DC electrification. The term is an abbreviation of Blocco automatico a correnti codificate .It is an extension of RS4 Codici...
, an extension of RS4 Codici - Pulse Code Cab SignalingPulse code cab signalingPulse code cab signaling is a form of cab signaling developed in the United States by the Union Switch and Signal corporation for the Pennsylvania Railroad in the 1920s...