The Future - Signalling Demonstration Princes Risborough North Signal Box
The Demonstration Area Our ambition is to open a ‘hands on’ demonstration area in the north end of the signal box housing our exhibits and showing how traditional mechanical signalling and telegraph systems operated using the levers, the bell telegraphs, the wood-cased instruments and telephones, and the polished brass switch plungers; the complete mechanical signal box experience, open to visitors and our heritage train passengers alike. There are a few hurdles to overcome first! For example we are going to need to install a new internal staircase at the north end of the building to allow separate access for the public. These staircases were common in many similar boxes, and we can copy that style so it looks the part. Such modification will require listed building consent, and will get caught up in modern day building regulations but in the context of an 1904 historical Grade II listed building. Initial drawings are in the process of being submitted to the relative departments and we hope to be given approval in due course. Although we are still a long way off from opening the area to the public on a regular basis, we have held some well received Open Days and have been able to demonstrate some items we have so far been able to assemble. One such item is a simulator which monitors train movements on the main Chiltern Lines and taps out authentic bell codes that would have passed between Risborough and the long vanished Saunderton and Haddenham signal boxes. There were bell codes to describe for example, passing a train along the line towards the next box, or closing a signalbox for the night (part time boxes only) and there was even a special code for ‘Royal Train approaching’. Woe betide any signalman who didn’t give a run of green signals to that train! Another artifact we’ve connected up to be able to demonstrate is a signal repeater instrument. These devices were used to show the aspect of signals that were out of sight of the signalman. They were wired up to switches on the actual signal itself and told the signalman that the signal arm had changed in response to him throwing the signal lever in the box. In railway terms ‘on’ means danger or caution, whilst ‘off’ means proceed. Our repeater cheats a bit and works directly from the lever in the box but it shows what a signalman would be looking out for. We also have a computer display which constrasts how a signaller on the present day Chiltern Railways controls the railway with how a 50’s signalman did. The signallers at Marylebone control all lines from London as far as Aynho and beyond. All routes and signals are set by the click of a mouse! The black oblongs along the line are called berths and if a train is present in that location, it will display the trains reporting number - a unique number assigned to every train and in the past referred to as a ‘headcode’. The map above shows the Princes Risborough area at a busy time! The train 1Y60 which has left Haddenham & Thame Parkway on its way to London is being given priority over train 2H61 which is being held on a red signal (number 178) on the outskirts of Princes Risborough on the Aylesbury branch. Train number 5P46 is stuck behind it at signal 180 at Little Kimble. The top lines are the Aylesbury to Amersham route showing 2C60 happily on its way to London and now under control of the London Underground signallers, with 2B44 on a clear run all the way from Wendover to the outskirts of Aylesbury. Contrast that with the below map of responsibilty of our Princes Risborough signalman of yesteryear. The one signalling centre at Marylebone replaces all the manual signal boxes along the line including at least four local boxes from 100 years ago. Progress indeed! (unless you were a signalman at Haddenham, or Saunderton, or Risborough South or North…)
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