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.
| Singular form signals |
|---|
 | 225a: passing permitted
|  | 226a: passing permitted
(automatic signal)
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| Singular branch-off form signals |
|---|
 | 227a-1: passing permitted
(lower signal: signal 234 or 236)
|  | 227a-2: passing permitted
(lower signal: signal 234 or 236)
|  | 227a-3: reduce speed
(lower signal: signal 237)
|
 | 227a-4: passing permitted with max. 45 km/h, reduce speed
(lower signal: signal 238 or 240)
|  | 227a-5: passing permitted with max. 45 km/h, reduce speed
(lower signal: signal 238 or 240)
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|
|
| Branch-off form signals |
|---|
 | 228a: passing permitted;
train is guided to the direction corresponding to the place of the signal. Service speed
|  | 229a: passing permitted;
train is guided to the direction corresponding to the place of the signal. Service speed
|  | 230a: 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
|
 | 231a: passing permitted ;
train is guided to the direction corresponding to the place of the signalwing: top=left, bottom=right. Count on stopping at station
|  | 232a: passing permitted ;
train is guided to the direction corresponding to the place of the signalwing: top=left, bottom=right. Count on stopping at station
|  | 233a: 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 |
|---|
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|  | 225b thru 233b:
(all) signal-wing(s) horizontal:
STOP in front of the signal
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| Warning signals |
|---|
 | 234: next regular signal does NOT show stop
|  | 235: next regular signal does NOT show stop.
(signal is automatic)
|  | 236: next regular signal allows speed higher than 45 km/h.
|
 | 237: reduce speed. Next regular signal allows max. 45 km/h.
|  | 238: reduce speed. Next regular signal shows stop.
|  | 239: reduce speed. Next regular signal shows stop.
(signal is automatic)
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|  | 240: reduce speed. Next regular signal shows stop.
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| Shunting signals |
|---|
 | 262: Stop shunting; but first: keep other tracks free.
|  | 263: passing allowed / resume shunting.
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| Heuvel-seinen |
|---|
 | 268: Pushing of part of the train to or over shunting-hill forbidden.
|  | 269: Pushing of part of the train to or over shunting-hill permitted.
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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.
 | green-white-white:
high speed allowed
|  | white-green-white:
medium speed allowed
|  | white-white-green:
low speed allowed
|
 | green-green-white:
high speed allowed, next signal will show medium speed
|  | green-white-green:
high speed allowed, next signal will show low speed
|  | white-green-green:
medium speed allowed, next signal will show low speed
|
 | yellow-white-white:
high speed allowed, next signal will show stop
|  | white-yellow-white:
medium speed allowed, next signal will show stop
|  | white-white-yellow:
low speed allowed, next signal will show stop
|
 | green:
high speed allowed
|  | yellow:
high speed allowed, next signal will show stop
|  | red:
stop
|
 | yellow 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
| | yellow 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:
- possibilites for speed reduction were too little
- three lights above each other gave less clear signals
- 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.
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
 | green:
passing permitted
|  | green flash with number 7:
passing permitted with 70 km/h
|  | green flash:
passing permitted with 40 km/h
|
 | yellow:
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.
|  | yellow 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
|  | double yellow:
reduce speed to half the service speed
|
 | yellow flash:
Ride on sight (an other train can occupy the
track
|  | yellow 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
|  | red:
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
 | green:
passing permitted with 40 km/h
|
 | yellow:
passing permitted with 40 km/h, next signal will show stop
|
 | yellow flash:
Ride on sight (an other train can occupy the
track)
|
 | red:
stop
|