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Aspect
3 Aspect signals
4 Aspect signals
Comparison
Flashing Yellows

Aspect

The colour of a signal lamp or combination of lamps on one signal is known as the aspect. The signal aspect provides an unambiguous message to the driver of a train. The signal lamp can also be made up of LEDs as this is now perceived to give the driver a clearer display of the aspect, especially when bright sunlight is shining onto a signal. In the UK, and simulated on SimSig there are three and four aspect signalling areas.

3 Aspect signals

The normal sequence of three aspect signalling is:

Green aspect Proceed Next signal displaying a proceed or caution aspect
Yellow aspect Caution Proceed but be prepared to stop at the next signal
Red aspect Danger STOP!

4 Aspect signals

The normal sequence of four aspect signalling is:

Green aspect Proceed Next signal displaying a proceed or preliminary caution aspect
Two yellow aspects Preliminary caution Proceed but be prepared to find the next signal showing one yellow aspect
Yellow aspect Caution Be prepared to stop at the next signal
Red aspect Danger: STOP!

Comparison

:usertrack:glossary:sigs3and4aspect.png 4 aspect signals


3 aspect signals

Flashing Yellows

In addition to the above on certain junctions is ‘Flashing Yellow Signalling’ this indicates that the facing points ahead are set for a diverging route, over which the speed of the train must be reduced. These are present in both three and four aspect signalling areas.

The normal sequence of three aspect flashing yellow signalling is:

- Green aspect

- Green aspect

- Single flashing yellow aspect

- Steady single yellow aspect with a junction indicator (the latter not shown to the signaller or on SimSig)

- Red aspect

The normal sequence of four aspect flashing yellow signalling is:

- Green aspect

- Double flashing yellow aspect

- Single flashing yellow aspect

- Steady single yellow aspect with a junction indicator (the latter not shown to the signaller or on SimSig)

- Red aspect

If there is a route set from the red aspect (5) upon approach the steady single aspect (4) will clear to the relevant aspect as described above in three and four aspect signalling.


Last edited by GeoffM on 15/09/2016 at 03:00