Scratch Building - Signals

Line side signals

by Charles Darley

Lower Quadrant Signal

The semaphore signal, or the arm signal was introduced as soon as locomotives started running and safety had to be considered on the tracks.

The first semaphore signals had the arm drop from the horizontal which indicated STOP (DANGER) to the down position to indicate a clear track ahead and the loco could proceed.

The signals were controlled by a fix connection to the signal box or activated at the signal themselves. The only problem was that if the signal operating connection broke the signal could fall from the Danger into the Clear position, not a desirable situation.

Upper Quadrant Signal

So the next development of the semaphore signal was to raise the signal to show clear. This was a much safer way of indicating for now if the operating connection broke the signal would fall to the DANGER position.

The picture, far right, shows the simple controls used to operate the signal.

Whether you wish to use the, early, lower quadrant or the, later, upper quadrant semaphore signals is up to you as both are appropriate to G-Scale tracks - and remember "It is your railway" !!

All of this signalling was fine in the daylight but as soon as dusk fell there was little chance that the engine driver would be able see the signal position so a method of showing the position of the signal was needed.

Lighting the signal

Originally an acetylene / paraffin burner was used to give an illumination behind the coloured lens red for danger and green for OK to pass.

When electricity was available to the signals then electric lamps were use for the illumination of the lenses.

On the G-Scale railway the lens can be lit by the use of a white LED and lens can be made from coloured gells such as are used for stage lighting.

Which side of the signal to obey?

The signal is painted red on one side which is the side to be OBEYED and is painted white on the backside to indicate it is not to be obeyed.

There is a great deal more about signalling but may be that is enough for the moment!