French railway signalling

However, during the First World War the interpenetration of trains between networks had increased, so that it became necessary to create a new unified signals specification.

However, in the Départements of Bas-Rhin, Haut-Rhin and Moselle, trains normally run on the right and so signals are placed on the right.

In fact, entering the wrong way is confirmed by a luminous counter-track entrance board (TECS), which, when lit, indicates that the following signals are placed on the right (on the left for Alsace and Moselle).

The first section of the safety regulations of the SNCF indicates that "any official, whatever his rank must obey passively and immediately any signals that are presented."

The block is a track section delimited by signals, whose length depends on the distance needed for a train to stop or slow down, in the worst conditions on the portion of line under consideration.

This moving block system is already in use on the central section of the RER line A between Nanterre-Préfecture and Vincennes.

In comparison, the moving blocks of the RER A allow a separation of only 90 seconds between trains at full speed.

The semaphore orders a temporary halt, usually because the block it protects is engaged by another train.

A driver passing a red light must advance at a speed within sighting distance until they reach the next permissive signal.

Slow 30 is a distant signal that indicates points in diverging position to be passed at a maximum speed of 30 km/h.

Slow 60 is a distant signal that indicates points in diverging position to be passed at a maximum speed of 60 km/h.

The disk is a deferred halt instruction, i.e. the driver may pass the signal with caution at a speed which allows the train to stop at any obstruction, but must stop at the next platform or points (even if the signal aspect would allow him to proceed).

Equivalent to the carré, it is used on sidings to control access to the main line or to protect points during shunting.

The white aspect indicates that the driver is allowed to proceed for shunting, keeping to 30 km/h over points.

The flashing white aspect indicates that the driver is allowed to proceed for shunting over a short distance.

The lozenge indicates that the upcoming speed limit is inferior by at least 40 km/h than the previous one and is equipped with a crocodile and in-cab repeater to enforce the warning.