Temporary colour light home signals
In 1968, the FR was running an intensive summer passenger service crossing trains at Minffordd and Tan-y-Bwlch (TYB). The single line sections were controlled by miniature staff instruments, but controlling heavy trains into the crossing loops was by fixed Flag Boards. The potential for a misunderstanding was therefore high. David Josey and his late friend and colleague, John Wagstaff, worked with no budget, no defined equipment, and no defined standards and rules to create a better system to control the entry into the loops. Firstly they bought, recovered and transported an assortment of redundant mechanical and electrical signalling equipment largely from the Southern Region of BR. See Signal Recoveries. From this eclectic collection a standard Loop signalling system was developed.
With the low train speeds and adequate braking they argued that trains could safely and sensibly run from a green aspect to a red. Nevertheless, it was important to remind drivers that they were approaching a passing loop and that they had to be prepared to bring their train to a stop at the approach (home) signal. For this John re-invented the old FR Disc Signals. This was to be painted a bright yellow on the approach side and have a large black W on its face. So the Whistle Caution Board came into being. From John’s time in Ghana, he suggested Up trains gave one long blast and Down trains two long blasts, so that the signalman could identify the position and direction of the approaching train.
The Home signals were three aspect, Red/Yellow/Green full size colour signal heads, with the Green aspect giving entry to the Main line and Yellow to the loop or any other line. This last only applied to the top end of TYB that had, at that date, a facing siding to Down trains. The existing ground frames at each end of the loops that controlled the entry/exit points and associated facing point locks (FPLs) were retained, as were the single line section entry flag boards - platform 'starting' signals. The colour light signal aspects were fed over the front (energised) contacts of signalling relays so detection and controls could be added to the circuits. Point & FPL detection was achieved by using semaphore signal two-position rotary contact boxes worked by the channel rodding. A Silec treadle was placed an engine length beyond each signal, so that the signal returned to Danger after the driver had passed the Clear aspect. See Train detection – Treadles. The signal control panel construction was based on Epson and Ewell Model Railway Club practice for model railway layouts. The control panel showed the layout and had lamps to indicate what aspect each home signal displayed. In each of the loops was a three-position rotary switch, which when in the vertical position, placed and maintained both signals from displaying a proceed aspect for that line. The switch could be turned to the left or the right, depending on the direction of travel intended. To clear the appropriate signal a push button by the signal indication then needed to be depressed. If the entry points were set for this movement then the signal cleared – to Green or to Yellow. If the points needed to be changed then the signalman walked to the ground frames and set the points. At each ground frame was located a locked box containing three buttons – Red, Yellow and Green. Pressing the appropriate green or yellow button cleared the signal. The signal could be returned to Danger by pressing the RED button at the ground frame, or returning the direction switch, on the control panel, to the vertical.
When the stations were unmanned the signals were turned off. As an unlit signal is a mandatory stop signal, ‘U’ signs were placed on the Home signal posts which allowed a train to pass it when the signal was unlit and the 'U' was displayed. These 'U' signs were a flat plate with a centre horizontal hinge to which was fixed a half-height plate. When in the up position the plate showed a large white U on a black background, and when down the signal number in black on a white background – fail-safe! The hinged plate was padlocked in either position.
The Railway Inspectorate accepted the proposal as a temporary measure until full signalling could be provided.