THE SIGNAL BOX

SIGNALS

SEMAPHORE SIGNALS

5. Combined Home and Distant signals

Combined Home and Distant signals (lower quadrant) Combined Home and Distant signals (somersault) Combined Home and Distant signals (upper quadrant)

Where signal boxes are close together, the necessary position of a Distant signal sometimes falls within the area of the adjacent box's signals. The Distant signal can be mounted beneath the Section signal of the box in rear, and it will be interlocked or slotted so as to ensure it is only cleared if the Stop signal has been cleared.


Three-aspect Colour Light signal
Lower quadrant Somersault Upper quadrant Colour Light

Outer Distant signals

Arrangement for Outer Distant signal

If the above arrangement does not provide adequate braking distance, an additional Distant arm can be placed on the previous Stop signal too. This would be called an Outer Distant whilst the other signal would be called the Inner Distant signal. Such signals require additional slotting to ensure that the Distant arm does not clear until the Stop signal ahead (aswell as the arm on the same post) is off.

The two signals in these illustrations represent the home and starting signals carrying the distant arms for the box in advance.


Arrangement for Colour Light Outer Distant signal
Arrangement for  distant signal applying to two boxes

In extreme situations, the Distant signal of the previous box can be shared by both boxes, slotted so that it doesn't show off until both signalmen have operated the signal lever. This arrangement isn't totally satisfactory as drivers cannot tell (when the signal is on) whether to brake for the first or second box's home signal. This is the only circumstance in the principles of semaphore signalling where greater information can be given to a driver by a Colour Light signal.

The signals in these illustrations represent the distant, home and starter of one box. The distant arms below the home and starter are controlled from the next box, but the distant in the foreground is controlled by both boxes.


Arrangement for  distant signal applying to two boxes (Colour Light)
Semaphore   Colour Light