The NS form and light signals


For questions, please ask me when it's about the light signals, or Dolf Wiertzema when it's about the Form signals.


Form signals

Singular form signals
225a225a: passing permitted 226a226a: passing permitted
(automatic signal)
   
Singular branch-off form signals
s227a1227a-1: passing permitted
(lower signal: signal 234 or 236)
s227a2227a-2: passing permitted
(lower signal: signal 234 or 236)
s227a3227a-3: reduce speed
(lower signal: signal 237)
s227a4227a-4: passing permitted with max. 45 km/h, reduce speed
(lower signal: signal 238 or 240)
s227a5227a-5: passing permitted with max. 45 km/h, reduce speed
(lower signal: signal 238 or 240)
   
Branch-off form signals
s228a228a: passing permitted;
train is guided to the direction corresponding to the place of the signal. Service speed
s229a229a: passing permitted;
train is guided to the direction corresponding to the place of the signal. Service speed
s230a230a: passing permitted with max. 45 km/h;
train is guided to the direction corresponding to the place of the signal. Count on stopping at station
s231a231a: passing permitted ;
train is guided to the direction corresponding to the place of the signalwing: top=left, bottom=right. Count on stopping at station
s232a232a: passing permitted ;
train is guided to the direction corresponding to the place of the signalwing: top=left, bottom=right. Count on stopping at station
s233a233a: passing permitted with max. 45 km/h;
train is guided to the direction corresponding to the place of the signalwing: top=left, bottom=right. Count on stopping at station
All form signals
    s225b225b thru 233b:
(all) signal-wing(s) horizontal:
STOP in front of the signal
   
Warning signals
s234234: next regular signal does NOT show stop s235235: next regular signal does NOT show stop.
(signal is automatic)
s236236: next regular signal allows speed higher than 45 km/h.
s237237: reduce speed. Next regular signal allows max. 45 km/h. s238238: reduce speed. Next regular signal shows stop. s239239: reduce speed. Next regular signal shows stop.
(signal is automatic)
    s240240: reduce speed. Next regular signal shows stop.    
Shunting signals
s262262: Stop shunting; but first: keep other tracks free. s263263: passing allowed / resume shunting.
Heuvel-seinen
s268268: Pushing of part of the train to or over shunting-hill forbidden. s269269: Pushing of part of the train to or over shunting-hill permitted.

Light system 1946

Light system '46 is the first signalling system in the Netherlands which solely relies on lights. There have been some experiments with light signals, starting in 1923. These lights used the configuration of the classic signals but don't use the signal arms. Reasons to come to the different system is the poor visibility of signals due to increasing electrification and more stringent safety measurements. Most important question was which signals were te be preferred, direction signals or speed signals. UIC regulations now said that speed signals were better.

A LS '46 signal pole consisted of a maximum of 3 lights, which could show green, white, yellow and red. The upper light controlled high speed, the second light controlled medium speed and the bottom light controlled low speed. Also information about the next signal could be read from the current signal. On free track only one light was needed, two lights were possible when high speed was never allowed, but they were never or almost never used. High speed was defined as 90 km/h or more, but only when the braking distance of the train on flat track would not be more than 1000 m. Medium speed was more than 45 km/h and lower than 90 km/h, but only when the braking distance of the train on flat track would not be more than 500 m. Low speed was 45 km/h or lower, but only when the braking distance of the train on flat track would not be more than 250 m.

l46_gwwgreen-white-white:
high speed allowed
l46_wgwwhite-green-white:
medium speed allowed
l46_wwgwhite-white-green:
low speed allowed
l46_ggwgreen-green-white:
high speed allowed, next signal will show medium speed
l46_gwggreen-white-green:
high speed allowed, next signal will show low speed
l46_wggwhite-green-green:
medium speed allowed, next signal will show low speed
l46_owwyellow-white-white:
high speed allowed, next signal will show stop
l46_wowwhite-yellow-white:
medium speed allowed, next signal will show stop
l46_wwowhite-white-yellow:
low speed allowed, next signal will show stop
l46_ggreen:
high speed allowed
l46_oyellow:
high speed allowed, next signal will show stop
l46_rred:
stop
l46_okyellow flash (75 fpm):
short braking distance (withing braking distance a signal can show stop, or the track where the train is going is a dead end
l46_okyellow flash (180 fpm):
at most 30km/h; careful driving, track may be occupied or a movable signal may be present which can show stop

LS '46 didn't prove it had all the advantages one hoped for:

  1. possibilites for speed reduction were too little
  2. three lights above each other gave less clear signals
  3. to give a green signal as part of a signal to reduce speed was considered wrong

These disadvantages led to (again) a completely new light signalling system, LS '55.


Light system 1955

LS '55 gave an almost complete de-coupling of speed signalling and clearance signalling. Basis of the system is (again) a signal pole with 3 lights, now of different color, green, yellow and red (a fourth, yellow, light was used in the beginning but has been abandoned). Additionally, a matrix board with a number for extra speed signalling can also be shown.
The lights control the clearance of the train. Only one light can be shown at a time (or the two yellow lights) Only the yellow light gives a speed signal (30 km/h, later 40 km/h) the other lights bear no information to speed.
If a specific speed has to be forced upon the train, a matrix board is shown.

There are some preperations to make the system fail-safe. First of all, the red light is always at the the bottom. All the light have long fanthom(?) hoods, to prevent sunlight from falling on the mirror and shining back to the driver. With heavy snow it is believed that snow can stay on the hood and thus prevent a light from being seen. When red is at the bottom, no snow lying on a hood can obscure this light. The only exception are signals with four lights. These signals always have two yellow lights. To be sure there is enough distance between the two lights, the second yellow light is put at the bottom.
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.

High signals

l55_ggreen:
passing permitted
l55_gk7green flash with number 7:
passing permitted with 70 km/h
l55_gkgreen flash:
passing permitted with 40 km/h
l55_oyellow:
reduce speed to 30 (40)km/h and keep braking until the train can come to a halt within sighting range of a stop-showing fixed signal.
l55_o6yellow with number 6:
reduce speed to 60 km/h. This speed has to be reached before the next signal and the next signal will not show stop
l55_oodouble yellow:
reduce speed to half the service speed
l55_okyellow flash:
Ride on sight (an other train can occupy the track
l55_o8kyellow with flashing number 8:
reduce speed to 80 km/h. This speed wil not be reached before the next signal but braking has to continue until the desired speed is reached
l55_rred:
stop

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

Dwarf signals

l55d_ggreen:
passing permitted with 40 km/h
l55d_oyellow:
passing permitted with 40 km/h, next signal will show stop
l55d_okyellow flash:
Ride on sight (an other train can occupy the track)
l55d_rred:
stop