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The French signalling system

Last revision date : wednesday, february 25th, 1998.
This document was released by my photoThierry DAVROUXMail to me...


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The TVM430 description is now available.
This page is only a part of a whole document treating of French signalling system.
I have translate in English only the part for the TVM system used on TGV lines.
I apologize for language mistake, English is not my native language, all remarks are welcome !

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The CAB Signal on the French TGV lines

Introduction.

The correct observation of signals placed at trackside may only be done if the train speed is below 220 Km/h. On the TGV lines, the speed of the trains is highter (270 Km/h or 300 Km/h) so the classic signals couldn't be used. The CAB signal system is used instead, all informations are transmited using the rails (TVM system : Transmission Voie-Machine) and shown in the TGV cabin on a shipped display.

The signals at the trackside are replaced by markers and staffs, and in the cabin by speed limit indication. Also some punctuals indications are shown on the display in the cabin : electrical switch, pantograph actions.

Informations are sent to the train using the rails, and some ponctual transmiters are also used. The train's speed is checked by a shipped computer, so the driver should respect the speed limit otherwise this system reduce automatically the speed or stop the train.

The CAB signal equip the TGV lines (TGV sud-est, TGV nord, TGV atlantique) and the tunnel throught the channel. The TGV running on thoses lines are shiped with the TVM equipment, but also some machines likes BB22000 series, used for express merchandises transport on the TGV sud-est line.

On TGV sud-est the sytem used is called TVM 300. It allow the train to run at max speed of 300 Km/h and used a continous informations systeme send using the rails. The TVM 300 may generate a maximum of 18 continous informations (only 14 are now used) and a maximum of 14 punctuals informations (only 11 used). The TVM 300 is also used for the TGV atlantique. But now a new system is used on new TGV lines (TGV nord, tunnel) : the TVM 430 installed on TGV R, Thalys and Eurostar. In a simplify, this new system is like a digital transmission of 27 bits informations. Only 21 bits are useful so the informations transmited are very more important : 2.097.152 informations (2^21) with TVM 430 (and only 18 with TVM 300).

Only the speed limit in the current block is transmited with the TVM300. With the TVM430, several others informations are transmited like the speed limit in the current block, the speed limit at the end of the block, the speed limit at the end of the next block, a distance, and the rate of climb (or descent) of the railroad. The speed control is something like with the KVB system, not by step like with the TVM300, the TVM430 use a curve reference for braking distance.

For more information about the TVM system read the Clemens Emanuel Tillier's page.

The CAB signal system.

Signals are shown in cabin using electro-mecanical displays. The first display is used for speed limit indicator, and an alternate display is used for punctuals informations like electrical switch or pantograph manoeuvring.

Speed limit indications.

The informations displayed with the TVM 300 are showed below and thoses of the TVM 430 are showed after.

Displays of the TVM300.

The following indications may be displayed by the TVM 300 system :

On-board indication : VLVL Indication (VL = "Voie libre" - free way).
This indication was shown on the first T.G.V. running on the new line T.G.V.-S.E., it allow to run at the max line speed, so 270 Km/h. In the new trains this indication is supersed by 270V.
The speed checking system is actived if the train's speed exceed 285 Km/h.

On-board indication : 300300V Indication.
This indication allow to run at the max line speed, so 300 Km/h.
The speed checking system is actived if the train's speed exceed 315 Km/h.

On-board indication : flashing 300300V Indication.
This indication allow to run at the max line speed, so 300 Km/h, until the end of the block, and prevent the driver that the 270A or 220A indications may be displayed on the next block.
The speed checking system is actived if the train's speed exceed 315 Km/h.

On-board indication : 270 warning 270A Indication - 270 warning (A="Avertissement").
This indication command to the driver, not to exceed the speed of 270 Km/h at the start of the next block.
The speed checking system is actived if the train's speed exceed 285 Km/h.

On-board indication : 270270V Indication.
This indication allow to run at the max line speed, so 270 Km/h.
The speed checking system is actived if the train's speed exceed 285 Km/h.

On-board indication : flashing 270270V Indication.
This indication allow to run at the max line speed, so 270 Km/h, until the end of the block, and prevent the driver that the 220A indication may be displayed on the next block.
The speed checking system is actived if the train's speed exceed 285 Km/h.

On-board indication : 220 warning220A Indication - 220 warning (A="Avertissement").
This indication command to the driver, not to exceed the speed of 220 Km/h at the start of the next block.
The speed checking system is actived if the train's speed exceed 285 Km/h.

On-board indication : execution 220220E Indication - 220 execution.
This indication command to the driver, not to exceed the speed of 220 Km/h.
The speed checking system is actived if the train's speed exceed 235 Km/h.

On-board indication : 160 warning160A Indication - 160 warning (A="Avertissement").
This indication command to the driver, not to exceed the speed of 160 Km/h at the start of the next block.
The speed checking system is actived if the train's speed exceed 235 Km/h.

On-board indication : execution 160160E Indication - 160 execution.
This indication command to the driver, not to exceed the speed of 160 Km/h.
The speed checking system is actived if the train's speed exceed 170 Km/h.

On-board indication : 80 warning80A Indication - 80 warning (A="Avertissement").
This indication command to the driver, not to exceed the speed of 80 Km/h at the start of the next block.
The speed checking system is actived if the train's speed exceed 170 Km/h.

On-board indication : execution 8080E Indication - 80 execution.
This indication command to the driver, not to exceed the speed of 80 Km/h.
The speed checking system is actived if the train's speed exceed 90 Km/h.

On-board indication : zeroZero Indication.
This indication command to the driver to stop before the next marker. It may be displayed after a speed limit at 80 Km/h (80A or 80A indications) but also after a speed limit at 160 Km/h (160E indication).
The speed checking system is actived if the train's speed exceed 90 Km/h, or 170 Km/h if this indication is displayed after the 160E.

On-board indication : redRed Indication.
This indication command to the driver to operate in visual mode and stop before the next marker. It indicate the entry of the train on a busy block.
The speed checking system is actived if the train's speed exceed 35 Km/h.


With the TVM300, the space between trains must be at least one block free. The follower train should normaly stop behind the protection marker of the buffer block, but, as the 000 indication (that command to stop behind the marker) allow to run at 170 or 90 Km/h, then a TGV could possibly enter at that speed in the buffer block. The red indication displayed in that buffer block automatically start a braking if the speed is still greater than 35 Km/h. So, if the TGV enter to much fast (170 or 90 Km/h), there is still enough distance so that braking be effective before enter in the occupied block.

On the TGV Sud-Est line, the normal block length is 2100 m and the braking distance at 270 Km/h is 8400 m (or 4 blocks).

On the TGV Atlantique line, the normal block length is 2000 m and the braking distance at 300 Km/h is 10000 m (or 5 blocks).

Depending of the location of the rails switches, it may be that the length of a block be reduced, we call it a reduced buffer block if the length is over 570 m, and minimal buffer block if the length is less than, (but however greater than 100 m ! that is the minimum length of a block).

For a normal brake, the 160 indication is displayed before the 000 (the speed control on that zone is 170 Km/h). For a brake with a reduced buffer block, an intermediate 080 indication is displayed between the 160 an the 000 (the speed control in the 080 and 000 blocks zones is then 90 Km/h). For a brake with a minimal buffer block, the principle is the same like with the reduced block, but an additive transmiter (punctual marker) is used, that limit the speed at 65 Km/h , and is placed in the 000 block zone.

The TVM300 also permit the use of permanent speed limitations (crossing points for reverse track) or temporary (works) on some zones. Thoses limitations are 220 Km/h, 160 Km/h and 80 Km/h. In the case of works with a more reduced speed, it's possible to mix them with the classic panels used for works, because, as the speed is 160 or 80 then the panels may be correctly sought by the driver.

Now, some examples of sequences that may be displayed on a 300 Km/h line.


Sequence of a brake behind a F marker with a normal buffer block :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull, a brake is requested at next block.
Marker on the left
On-board indication : 270 warningBraking, reduce speed to 270 Km/h.
Marker on the left
On-board indication : 220 warningBraking, continue to reduce to 220 Km/h.
Marker on the left
On-board indication : 160 warningBraking, continue to reduce to 160 Km/h.
Marker on the left
On-board indication : zeroBraking, stop behind the next marker (control = 170 Km/h).
FMarker on the left
On-board indication : redEntering the buffer block (speed control = 35 Km/h).
FMarker on the left
On-board indication : redEntering the block occupied by the other train.


Sequence of a brake behind a NF marker with a reduced or minimal buffer block :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull, a brake is requested at next block.
Marker on the left
On-board indication : 270 warningBraking, reduce speed to 270 Km/h.
Marker on the left
On-board indication : 220 warningBraking, continue to reduce to 220 Km/h.
Marker on the left
On-board indication : 160 warningBraking, continue to reduce to 160 Km/h.
Marker on the left
On-board indication : 80 warningBraking, continue to reduce to 80 Km/h.
Marker on the left
On-board indication : zeroBraking, stop behind the next marker (control = 90 Km/h).
NfMarker on the left


Sequence for slowing down to 160 for changing track :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull,a brake is requested at next block.
Marker on the left
On-board indication : 270 warningBraking, reduce speed to 270 Km/h.
Marker on the left
On-board indication : 220 warningBraking,continue to reduce to 220 Km/h.
Marker on the left
On-board indication : 160 warningBraking, continue to reduce to 160 Km/h.
Marker on the left
On-board indication : execution 160Buffer block limited at 160 (control = 170 Km/h).
Plaque NfMarker on the left
On-board indication : 160Next block, displayed untill cross the switching.

On-board indication : 300Now, again normal speed (but on reverse track).


Sequence for slowing down to 80 Km/h on a work zone :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull,a brake is requested at next block.
Marker on the left
On-board indication : 270 warningBraking, reduce speed to 270 Km/h.
Marker on the left
On-board indication : 220 warningBraking, continue to reduce to 220 Km/h.
Marker on the left
On-board indication : 160 warningBraking, continue to reduce to 160 Km/h.
Marker on the left
On-board indication : 80 warningBraking, continue to reduce to 80 Km/h.
Marker on the left
On-board indication : execution 80Buffer block limited at 80 (control = 90 Km/h).
Marker on the left
On-board indication : execution 80Block with work (+ classic work panels).
Rail works with speed limitation less than 40 Km/hAdvanced speed indication for rail works : 40 Km/h
Execution of speed limit for rail works : 40 Km/h
End of rail works
Marker on the left
On-board indication : 300Now, again normal speed.

Displays with the TVM 430.

With the TVM430 the basics principles of the TVM300 are kept, for the on-board displays. However some displays has been enhanced for a best readibility, and the number of displays is also very more important. With a shiped computer, the informations trasmitted by the track are converted : the display is translated and computed depending of severals parameters (type of machine, maximal speed and breaking performance for that engine, profile of the track, and indication in the next block).

With the TVM430 the differents speeds indications that may be displayed are the following :

320 (reserved), 300, 270, 230, 220, 200, 170, 160, 130, 080, 060, 000 and red.

Almost all of the displays may be showned using the three forms : maximal speed, announced speed, execution speed. The signs has the same form like with the TVM300 :

A great difference between the TVM430 and the TVM300 is that, if the next block display is more restrictive than the present, then the display flashes.

Now, some examples of sequences that may be actually displayed by the TVM430 system.

Maximal speed (also called execution speed of normal run)

On-board indication : 300Speed ceiling 300 Km/h.

On-board indication : flashing 300Speed ceiling 300 Km/h, but braking at the next block.

On-board indication : 270Speed ceiling 270 Km/h.

On-board indication : flashing 270Speed ceiling 270 Km/h, but braking at the next block.

On-board indication : 230Speed ceiling 230 Km/h.

On-board indication : flashing 230Speed ceiling 230 Km/h, but braking at the next block.

All thoses indications allow to run at the ceiling speed displayed (300, 270 or 230 Km/h).
In the case of a flashing display, then the driver is informed that the speed limit in the next block is less than it is in the present block. And so he can prepare the action to slow down (stop the traction or begin the braking).

Announced speed.

On-board indication : 270 warningAnnounced speed 270 Km/h.

On-board indication : flashing 270 warningAnnounced speed 270 Km/h, and less at the next block.

On-board indication : 230 warningAnnounced speed 230 Km/h.

On-board indication : flashing 230 warningAnnounced speed 230 Km/h, and less at the next block.

On-board indication : 220 warningAnnounced speed 220 Km/h.

On-board indication : flashing 220 warningAnnounced speed 220 Km/h, and less at the next block.

On-board indication : 170 warningAnnounced speed 170 Km/h.

On-board indication : flashing 170 warningAnnounced speed 170 Km/h, and less at the next block.

On-board indication : 160 warningAnnounced speed 160 Km/h.

On-board indication : flashing 160 warningAnnounced speed 160 Km/h, and less at the next block.

On-board indication : 130 warningAnnounced speed 130 Km/h.

On-board indication : flashing 130 warningAnnounced speed 130 Km/h, and less at the next block.

On-board indication : 080 warningAnnounced speed 80 Km/h.

On-board indication : flashing 080 warningAnnounced speed 80 Km/h, and less at the next block.

On-board indication : 060 warningAnnounced speed 60 Km/h.

On-board indication : flashing 060 warningAnnounced speed 60 Km/h, and less at the next block.

The display of thoses indication, command to the driver to slow down the train so that he can enter the next block at the indicated speed. In the case of a flashing display, then he also know that the speed in the next block is less and so he can continue the brake action.

Execution speed (slow zone).

On-board indication : execution 230Execution speed 230 Km/h.

On-board indication : flashing execution 230Execution speed 230 Km/h, and less at the next block.

On-board indication : execution 220Execution speed 220 Km/h.

On-board indication : flashing execution 220Execution speed 220 Km/h, and less at the next block.

On-board indication : execution 200Execution speed 200 Km/h.

On-board indication : flashing execution 200Execution speed 200 Km/h, and less at the next block.

On-board indication : execution 170Execution speed 170 Km/h.

On-board indication : flashing execution 170Execution speed 170 Km/h, and less at the next block.

On-board indication : execution 160Execution speed 160 Km/h.

On-board indication : flashing execution 160Execution speed 160 Km/h, and less at the next block.

On-board indication : execution 130Execution speed 130 Km/h.

On-board indication : flashing execution 130Execution speed 130 Km/h, and less at the next block.

On-board indication : execution 080Execution speed 80 Km/h.

On-board indication : flashing execution 080Execution speed 80 Km/h, and less at the next block.

On-board indication : execution 060Execution speed 60 Km/h.

On-board indication : flashing execution 060Execution speed 60 Km/h, and less at the next block.

Thoses indications command to the driver to not overide the speed displayed. In this case, it is a normal slow zone, for a cross point or a works zone. If the display flashes, then the driver also know that the speed limit in the next block is less than in the actual, and so he can continue the braking.

Indications 000 and red.

On-board indication : zeroZero indication (announced speed 000).

On-board indication : redRed indication.

The zero display command to the driver to stop behind the next marker.
The red indication command to the driver to operate in visual mode and stop before the next marker. It indicate the entry of the train on a busy block.


Sequence of display for a TGV R braking on a 300 Km/h
line, behind a F marker with a normal buffer block :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull, a brake is requested at next block.
Marker on the left
On-board indication : flashing 270 warningBraking, reduce speed to 270 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 230 warningBraking, reduce speed to 230 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 170 warningBraking, reduce speed to 170 Km/h, and continue the brake.
Marker on the left
On-board indication : 000Braking, stop behind the next marker.
FMarker on the left
On-board indication : redEntering the buffer block.
FMarker on the left
On-board indication : redEntering the block occupied by the other train.


Sequence of display for a TGV R braking on a 300 Km/h
line, behind a NF marker with a reduced buffer block :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull, a brake is requested at next block.
Marker on the left
On-board indication : flashing 270 warningBraking, reduce speed to 270 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 230 warningBraking, reduce speed to 230 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 170 warningBraking, reduce speed to 170 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 80 warningBraking, reduce speed to 80 Km/h, and continue the brake.
Marker on the left
On-board indication : 000Braking, stop behind the next marker.
NfMarker on the left


Sequence of display for a TGV R braking on a 300 Km/h
line, for a cross point limited at 160 Km/h :

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull, a brake is requested at next block.
Marker on the left
On-board indication : flashing 270 warningBraking, reduce speed to 270 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 230 warningBraking, reduce speed to 230 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 170 warningBraking, reduce speed to 170 Km/h, and continue the brake.
Marker on the left
On-board indication : 160 warningBraking, reduce speed to 160 Km/h.
Marker on the left
On-board indication : execution 160Speed limited at 160 Km/h.
NfMarker on the left
On-board indication : execution 160Next block, displayed untill cross the switching.

On-board indication : 300Now, again normal speed (but on reverse track).


Sequence of display for a TGV R braking on a 300 Km/h
line, for a slow zone at 160 (works zone) then a stop before a cross point.

On-board indication : 300Normal speed.
Marker on the left
On-board indication : flashing 300Carrefull, a brake is requested at next block.
Marker on the left
On-board indication : flashing 270 warningBraking, reduce speed to 270 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 230 warningBraking, reduce speed to 230 Km/h, and continue the brake.
Marker on the left
On-board indication : flashing 170 warningBraking, reduce speed to 170 Km/h, and continue the brake.
Marker on the left
On-board indication : 160 warningBraking, reduce speed to 160 Km/h.
Marker on the left
On-board indication : execution 160Limited speed block to 160 Km/h for works zone.
Marker on the left
On-board indication : flashing execution 160Next block also limited.
Marker on the left
On-board indication : flashing 080 warningBraking, reduce speed to 80 Km/h, and continue the brake.
Marker on the left
On-board indication : 000Braking, stop behind the next marker.
NfMarker on the left

Punctuals indications.

An alternate display is used to show additionnals informations :

The following informations may be displayed :

On-board indication : speed checkingSpeed checking Indication.
For each speed limit indication, a control of train's speed is done to ensure that the driver does not exceed the maximum speed allowed. If the train's speed is over the indication limit, then the speed checking indication is displayed and the driver should immediatly brake to reduce the speed. If he don't brake then the system brake automaticaly the train until stop.

On-board indication : electrical switchElectrical switch Indication.
This indication demand to the driver to switch off the electrical power (open the circuit breaker). If the driver don't open the circuit breaker, then the system do it automaticaly. The open of circuit breaker is automatic, but the retablishment of the circuit should be done mannualy.

On-board indication : pantograph downPantograph Indication.
This indication demand to the driver to switch off the electrical power (open the circuit breaker) and then to descend the pantograph. The both actions are done automaticaly if the driver fail to do. This action should be done between parts of lines powered by different type of current. In France the SNCF use two type of power : 25,000 volts AC 50 Hz and 1,500 volts DC. All new lines use modern and industrial power of 25,000 volts, but as the TGV may also run on oldest lines it may also use the old 1,500 volts.

Markers and staffs used on the railroad.

On hihg speed line the blocks are signalled using specials markers, instead of signals on the classics lines. All lines are equiped to allow back way usage, so symetrical markers are used :

Marker on the leftMarker placed on the left of the railroad (normal way).
Marker on the rightMarker placed on the right of the railroad (back way).
Thoses markers come with an identifierForNfdepending on the marker may be pass or not. Letter F mean "franchissable" (or may be pass), and letters Nf mean "Non franchissable" (marker may not be pass).

Manoeuvring itinerary :

Some markers with the identifierNfare also equiped with a white light. This light call "feu de manoeuvre" (manoeuver signal) is the start of a manoeuvring itinerary.

Nevertheless, for some special manoeuvring itinerary, there is not a marker near the start point. So, a special staff is used to mark the start point of that manoeuvring itinerary :

Manoeuvring staff on the leftManoeuvring staff located on the left of the railroad (normal way).
Manoeuvring staff on the rightManoeuvring staff located on the right of the railroad (back way).

Manoeuvring staffs are also equiped with a white light.

Markers and staffs are also equiped of protection switches, allowing to close the signals (red indication displayed on the CAB signal). This is a security system that can be used manually, to protect a part of the TGV line. The markers and staffs equiped with such switches are identified with the following sign :

Protection switchProtection switch installed.

Entry an exit panels signalling the TVG lines.

1. Old panels.

At the begining, the start of a TGV line was identified by three advertising panels distants of 100 m, and a TGV pannel at the signal of entry.

300 m before the entry signal :
Old T.G.V. panel
3 marks

Then 200 m before the entry signal :
Old T.G.V. panel
2 marks

Then 100 m before the entry signal :
Old T.G.V. panel
1 mark

With the entry signal :
Old T.G.V. line's entry panel

The exit of a TGV line was only identified by a pannel installed around 100 m before the first signal of the classic line :

Old end-of T.G.V. line panel

2. New panels.

The olds "TGV" panels are now supersed by news "CAB" panels, indicating that the railroad is equiped with CAB-signal system. The new panels used are :

Panel advertising before the start of the CAB equiped line :
Warning C.A.B. panel
Panel indicating start of the CAB equiped line :
C.A.B. panel
Panel indicating exit of a CAB equiped line :
End of C.A.B. panel

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