THE SIGNAL BOX

SIGNALS

BRITISH RAILWAY SIGNALS

Banner Signals

Banner repeater signal

The banner signal was invented by W R Sykes & Co around 1900 as electrical operation of signalling was beginning to become a practicality.

The "arm" of the signal rotated on an opaque disc in an enclosed glass case, allowing lightweight operation in a clean environment.

Many early examples had red-coloured "arms" and were used in place of conventional signals at locations of poor lighting or limited clearance. However, with the arm being around a third of the size of a normal signal, they weren't really suitable for use on higher-speed sections of line.

However, unlike many adventurous signal designs, the banner signal did not become extinct. Instead, it was adopted nationwide as a "repeater" signals, to show the position of a signal ahead which might be obscured by station buildings or a bridge. Red-coloured arms continued to be used, initially, but around 1924 a change was made to using yellow arms for repeaters. The now universally accepted use of black arms was introduced in 1929.

This principle of repeating signal indications survives to this day - even in areas of colour light signalling - although the majority have now been replaced by fibre-optic light signals which give the same indications without any moving parts.

Banners were also used in place of semaphore distants into recent years on the ex Belfast & County Down line to Bangor of the Ulster Transport Authority. These looked to be standard banner signals with the arm was coloured yellow.

Banner repeater signals at Crystal Palace
Photograph 2002, by Peter Grant

Double-face repeater signal

The signal illustrated here has no moving parts. Instead, two opaque discs are provided but only one is lit at a time. Being in a tunnel, the unlit disc is not visible to drivers.

.It is located within Crystal Palace Tunnel on the Down Line, repeating signal VC729. It is worth noting that the indications work as a lower quadrant signal would - an interesting contrast with the state-of-the-art Colour Light signalling with which it works. A similar signal is provided in the tunnel on the Up line, but here the indication is upper quadrant.

Banner signals only show "on" or "off" and do not repeat the actual indications of the signal ahead, be it semaphore or Colour Light. For example, in this picture the lower banner at "off" would indicate that the signal ahead has been cleared , but does not identify whether the signal is showing yellow, double-yellow or green.

Additional notes by Peter Grant and Tin Lockley