Dutch text
The NS form and light signals, Light system 1955.

High signals

In 1955 the NS switched to a new signaling system. The new 1955 signaling system gave an almost complete de-coupling of speed and clearance signalling. The base signal pole has three lights (In the beginning there was a fourth, yellow, light but that light has been abandoned.) The three basic lights have different colors, green, yellow and red.
Additionally, a matrix board board with a number for extra speed signalling can also be shown.
The three lights control the clearance of the track ahead of the train. Only one light can be shown at a time. The yellow light gives a speed signal, at first 30km/h, later 40km/h. Green allows passing and red orders stop.
If a specific speed has to be forced upon the train, a matrix board can be shown.

green green flash with number 7 green flash
passing permitted passing permitted with 70 km/h passing permitted with 40 km/h
Preparations to make the system fail-safe :
The lights are fitted with a long "sun cap" above each light to prevent sunlight from falling on the mirror and shining back to the driver.
The red light is always at the the bottom. With heavy snow it is believed that snow can stay on top of the "sun cap" and thus prevent a light from being seen.
When red is at the bottom, no snow lying on a "sun cap" can obscure this light.
The matrix board have more reflectors in it than necessary to show a number. If sunlight reflects on the mirrors, a nonsense figure would be displayed.
yellow yellow flash
reduce speed to 40km/h the next signal can show a stop sign. Ride on sight, reduce speed (max 40km/h) so that the train can stop before any obstackel.

Why is the green light flashing when a number is shown and yellow not? Fail-safe! Green flash is a more restrictive signal than green flash 6. So when in case of a failure the number is not shown, yellow 6 will turn into yellow, being a more restrictive signal. Green 6 would turn to green and the driver would think that track speed is allowed, which is not. Therefore the flash is introduced.

yellow with number 6 yellow with flashing number 8 red
reduce speed to 60 km/h. This speed has to be reached before the next signal and the next signal will not show stop reduce speed to 80 km/h. This speed will not be reached before the next signal but braking has to continue until the desired speed is reached stop

Dwarf signals

green yellow
passing permitted with 40 km/h. passing permitted with 40 km/h, next signal will show stop.
yellow blinking red
Ride on sight (an other train can occupy the track). stop
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updated : februari 12th,2004 Designed by:
Rik Boers & Bart Ponsen