We were invited to take a look at the operation of a signalbox when we arrived at Bridgnorth, whilst the engine tender was filled with coal. The signalbox is small, and reached by wooden steps. Inside the box itself, there are two signalmen and our party fills the remaining space! Once we had arranged ourselves along the rear wall, to keep the lever frame clear, our guide introduces us to the signalmen.
"He's going to do a shunt, and you'll see what's happening on the display, ok? I'll let him do the talking and I'll stand at the end."
One of the signalmen takes over.
"What we've got is a block diagram of the signalbox. The red indications show where the trains are." He points to an overhead diagram in a frame of the layout of the station. The frame has small red lights on certain lines which illuminate when a train is on the track.
"Your train is in platform two. What we've got to do, is to release your engine from that train, so what we're using is a light engine which is taking a service train out first thing in the morning. He's going to be shunting up to the bracket signal, he's then going to come back onto your train on platform two, shunt them all up, allow your engine to go up into the coal, push the coach up into platform two, uncouple, and shunt back up to allow your engine to come back out of the yard. The indicators show where the train movements are, as a lot of the places we can't see visually, so we have to rely on these indicators."
He then points out the levers which are in front of us on the floor, and explains their uses.
"What we have on the lever frame - red levers for signals, black levers for points, the blue ones are for facing point locks which locks the points into position. There's another lever down here which is a blue and brown one which gives a release to a ground frame. There's another 15 frame signal which brings them out onto the main line, which is clear now. (Lots of lever movement as the points and signals are changed.)
"What I've done there is put No. 14 back normal which means the crossover here moves to allow the train engines to come out and then No. 13 which is facing point lock, which locks No. 14 point into position. No 11 which is facing points lock which locks 12, and I've got an indicator here which tells me the position of the points. Once I've got those two there, it allows me to pull the signal........."
We watch as the operation is completed, and our engine is being re-coaled.
It is worthwhile to add that point operation beyond the "shed road" into the sheds themselves is controlled locally - that is to say by footplatemen and shed staff, and indicated by a ground frame which is a red disc with a white stripe. This works in much the same way as a normal signal.
On occasion, during frosty weather, points will freeze, along with signals. In this eventuality, we have to resort to the kettle to thaw them out. Meanwhile, hand signals can be employed.
The system of bells and token operation is explained as used at Bewdley. "There we operate both single and double lines, with Platform one being the up line, and Platform 2 being the downline. Platform 3 is bi-directional, that is, running in either direction, controlled between Kidderminster Station and Bewdley." Our driving tutor explains signalling and token operation, particularly on the bi- directional line, which is operated by a series of bells between Kidderminster and Bewdley. " If a train wishes to travel between stations, both stations have to agree that the line is clear and, on acknowledgement from the other, levers are pulled to allow the train onto the track. Both signal boxes must pull the levers, otherwise the points and signals will not work. This allows several trains to travel in one direction only, and when the line is cleared after the last train, the line can be opened to run in the opposite direction. This is called a "total block" system, as it blocks travel in the opposite direction until the train has cleared the section. Usually, only one train can work on a particular section, using a physical token, which can only released from the machine when both signalmen in their individual boxes press the lever. This prevents a token being issued accidentally or too many tokens being given out. The machine also blocks the starting signal. You can't pull the starting signal for each section until the token has been released from the machine. Conversely, until the token has been put back in the machine, another train cannot be issued with a token to use the same section. There are safety checks all the way through. That's why the driver, when he picks up a token from a station, always checks the name of the section to make sure he's got the right one."
"The famous accident regarding tokens, happened in 1920/21, something like that, when the driver was given back the token he had just given up for the section he had just left, and because he didn't read it, thought it was the token for the next section, and met a train coming the other way. Human error - failure to check all the way through. We always mind someone else, minding somebody else, and so on. The section between Bewdley and Kidderminster doesn't work on a token, even though it is a single line, it works on a total block, it's full track circuited all the way along, and in both signal boxes, they can see the progress of the train as it goes through to Kidderminster - the electric bells act as a safety check, when the track circuits are activated the signals are locked."
"The box is situated in it's original position as when the railway closed down. When you go outside, look at the brickwork. It goes up to a certain height, and it just goes in slightly. Although the lower part of the box is the original building, it was partly demolished when acquired. To restore the building to full operation, the upper half of the box was taken from an unused signalbox elsewhere, and grafted to fit. It is not quite the same size, but unless you have this fact pointed out to you, you would not realise it. The lower half of the building is in brick, and the top half is wooden, and yet looks like it was originally constructed this way."
Many thanks are extended to Graham Hill and associate members of all signalboxes on the Severn Valley Railway during that day, for their hospitality and information provided.
