2025 marks 40 years of RETB on the Far North Line. So I was delighted to receive a digital copy of the pamphlet produced by Scotrail to mark its introduction and explain the technology. Graeme Mackay, one of our members, found a copy when tidying his loft and knew I'd be interested.
As an introduction to reproducing the pamphlet in full I asked Iain MacDonald, one of our long-standing committee members, for his personal recollections as a signalman during the transfer from conventional signalling to RETB:
We had had a very severe storm previously [1978] with many of the overhead wires brought down, so a system of getting the Key Token instruments to work by radio was developed which in turn gave rise to RETB signalling.
By the time of the public announcement, this system had been in use for around a year, alongside the normal Electric Token Block.
The trial proved to be quite successful, so in 1984 it was decided that the RETB system would be used from Dingwall to Kyle, and later the Wick /Thurso lines (two trains ran Wick-Georgemas and Thurso-Georgemas, combining to come south, splitting there on the northbound journey).
Now, who were the new signallers to be? The jobs were advertised as temporary as no 'marks' allocation* was available for the new system. I didn't fancy my chances of getting a decent job somewhere else at 48 years of age and I decided to apply. My colleague was extremely anxious about applying, I told him if he didn't he would be shovelling ballast! In the end he applied and we were both successful with our applications.
We started training in a mock-up, learning how to issue tokens etc but with no-one on the other end. Once Dingwall to Kyle was working, attention turned to the Far North Line. There, things didn't go well for the installation teams. Test Coach Iris was up and down the line, it being extremely difficult to get Lairg and Forsinard to work properly. This was near Christmas 1985 and Chris Green decided we'd go live with this at New Year. Commissioning morning was one to remember!
The distillery level crossing at Invergordon caused me quite a bit of concern - it was busy but had no signals, only a crossing keeper paid by the distillery. It relied on the signaller telling the keeper to close the gates and the keeper confirming the crossing was closed. If the signaller forgot to phone, the trains ran at line speed through the level crossing. I made metal covers to put over the Invergordon button on the keyboard and marked it "Distillery L/C", I also made other covers to use when permanent way staff had the section by phone.
The very far north section was postponed and we were getting very bad publicity with the Press reporting that the trains were crawling along and no one knew where they were. The system was new and all the staff were inexperienced, but in the end we got there.
*On conventional signalling systems with manned signalboxes at many locations, the pay grades were determined by a 'marks' system where marks were allocated to each signalbox according to the number of trains being handled, lever movements, bell signals, train register entries, level crossings and shunting movements.