Block signals provide up to 6 track occupancy aspects, and provide indications for 3 speeds in the main signal head. Additional speeds are signaled by supplementary heads, as are directional indications.
French railways have an extremely diverse history of mechanical signals. These most often consisted of boards which rotated between presentation face-forward and edge-on. The night aspects were provided by spectacles in the face of the boards turning a lamp the proper color. When the signal rotated to edge-on, the white light was visible for the clear indication. Semaphores were also occasionally used for mechanical signals, notably for a permissive stop indication, and in stacks for route indication. In an attempt to standardise the signal aspects and indications, the French government produced a "Code des Signaux" in 1885, which resulted in standardisation of the most common signals, but each railroad still used some unique signaling. Later the lamps were moved below the signal board to form assemblies of colorlights which corresponded to more than one mechanical board when installed in clusters.
In the early 1930's, colorlight signals were experimented with, originally corresponding to the 1885 code and other individual railroad practise.
The SNCF predecessor railroads merged in 1938 (with previous mergers shown in parenthesis):
AL Alsace-Lorraine
Est Eastern
PLM Paris-Lyon-M'editerran'ee
Nord Northern
Etat State ----+--(1909)-- ETAT
Ouest Western --+
PO Paris-Orl'eans --+
Midi Southern --------+--(1934)-- PO-Midi
In 1930 it was decided to reform the French signal code to eliminate
the white clear aspect to be replaced by green, and to use yellow for
caution instead of green. This corresponded with the general change
from white/green/red to green/yellow/red throughout the world, due to
the dangers associated with a white clear. The color changes
consisted both of the color of boards for day aspects as well as the
color of lights for night aspects. This change in the French signal
code is commonly referred to as Verlant, after M. Verlant, traffic
superintendent of the PLM who presided over the committee of the
various railroads which recommended the changes to the French
Minister of Public Works.
The first phase, completed in 1935, was to replace the use of yellow in stop signals by violet. These were yard signals, and the white clear was then changed to lunar white. Yellow was then added to the disque (deferred stop), and the green removed from the semaphore stop indication. Approach and speed reduction indications were then changed from green to yellow, and finally, clear indications from white to green.
A few early colorlight installations were based on a design for the 1885 code, and had to be completely changed. Some installations anticipated the change, and consisted of two heads mounted side-by-side, providing the 2-light 1885 indications. When the change was made to the new code, one of the heads was removed, and the colors of the lenses were changed from white/green to green/yellow.
The new signal code was refined slightly in 1941, and is the basis for modern signal practice. Originally, a small lunar white modifier (oeilleton) was added to block and interlocking signals as a call-on indication for a permissive stop and proceed to be used with a semaphore (single red). Later, these were removed from block signals, and are now installed only on interlocking signals so that a red lamp failure (one of two in a carr'e absolute stop indication) will still indicate absolute stop. As speeds increased, additional aspects were added in the form of flashing lights, as were explicit speed signals. Mechanical signals have largely disappeared from the SNCF, but 1941 code signals can still occasionally be seen.
1. INTRODUCTION
2. SIGNAL TYPES AND LOCATION
2.1 Signal Locations
2.2 Block Signals
2.2.1 BAL -- Block Automatique Lumineux Permissif
2.2.2 BAPR -- Block Automatique `a Permissivit'e Restreinte
2.2.3 BMU -- Block Manuel de Double Voie
2.2.4 BMVU -- Block Manuel de Voie Unique
2.3 Interlocking Signals [BAL]
2.3.1 Mainline Interlocking Signals [C]
2.3.2 Yard Interlocking Signals [Cv]
2.4 Early Colorlight Signals
2.5 Speed Signals (Signaux Indicateurs de Vitesse Limite) [TIVP, TIV, TIVR]
2.6 Direction Indicators (Signaux Indicateurs de Direction)
[TIDD, ID, TECS, TSCS, G, D, SAS, Imp, TIP]
2.7 Switching Signals (Signaux de Manoeuvre) [SLM]
2.8 Starting Signals (Signaux de D'epart) [SLD, TLC]
3. SIGNAL ASPECTS AND INDICATIONS
3.1 Stop Signals [C, Cv, S, GA]
3.2 Restricting Signals [S, M, (M)]
3.3 Approach Signals [A, (A), RR, (RR)]
3.4 Clear Signals [VL, (VL), R, (R)]
3.5 Directional Indicators [ID]
3.6 Switching Signals [SLM]
3.7 Starting Signals [SLD]
3.8 Switch Point Indicators (Signaux Indicateurs de Direction des Aiguilles)
4. FIXED BOARDS AND ADDITIONAL SIGNALS
4.1 Speed Limits -- Permanent (Limitations de Vitesse -- Temporaires)
4.2 Speed Limits -- Temporary (Limitations de Vitesse -- Permanentes)
4.3 Directional/Siding Boards (Indications de Destinations Particuli`eres)
4.4 Stop Orders (Signal d'Arr^et)
4.5 Telephone Communication Signals (Signaux de Communication T'el'ephonique)
[DD,VAT]
4.6 Station Boards (Panneaux de Gares)
4.7 Temporary Single Track Boards (Panneaux de Voie Unique Temporaire) [VUT]
4.8 Grade Crossing Boards (Panneaux et Rep`eres de Passages `a Niveau) [PN]
4.9 Other Fixed Boards
4.10 Electric Traction Signals (Signaux Propres a la Traction 'Electrique)
4.11 Hand/Whistle Switching Signals (Manoeuvres: Signaux a Main et Sonores)
4.12 LGV Boards and Signals (Panneaux et Signaux de Lignes `a Grande Vitesse)
4.13 TGV Cab Signals (Signalisation en Cabine TGV)
Last updated 8 November 2004
©2003–2005 James P.G. Sterbenz
<jpgs@sterbenz.org>