Cambrian Dispatcher


1. Of Railfans and Railwaymen
2. A Machynlleth Sunday
3. Cuppa with John Gwynne
4. A Railwayman's Railwayman


Three: A Cuppa with John Gwynne


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The Machynlleth
interlocking plant:
technology still
in daily use.
"Shake off the rain, put your things down.  So you're a railway enthusiast, eh?  Would you like a coffee?"  I gave my name and allowed as how I was indeed a railfan, from the States, and would very much like a coffee.  My host busied himself setting up the waterpot on a small electric ring, and we chatted while the water heated: I learned that this gracious man was John Gwynne, a career railwayman first with BR and now with Railtrack, the new privatized railway infrastructure company.  Encouraged by John, I began to poke about the tower.    Larger than it looked from the platform, the tower stretched at least 30 feet from end to end.  Running the entire way down the trackside wall was a classic manual or "armstrong" interlocking plant and a model board covering the whole station and yard complex.  On the back wall, opposite the levers, stood a desk loaded down with three computer monitors and an intimidating array of phones, radios, keyboards, and communications equipment.  In contrast to the peeling paint on the exterior walls of the tower, everything inside-- the interlocking levers, the desks, the very floor itself-- was polished, well tended, and spotlessly clean. 


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John Gwynne
confers with a
maintenance of
way foreman out
on the line from
his controller's
After fussing with the instant coffee and proffering the sugar and cream, John led me on a walk-through of the tower. The manual plant, he explained, covered far more than the Machynlleth depot alone: through relays and signal lines, its levers actually set the turnouts and signals all the way to Dovey Junction, four miles down the way.  Yet the interlocking plant was just the beginning of John's responsibilities.  Gesturing at that deskfull of computer screens tucked away in the back corner, he explained that they constituted a Radio Token signaling system which covered the entire remainder of the Cambrian lines outside the Machynlleth interlocking.  No humble towerman, John was actually the first-trick controller or dispatcher for the entire railway grid of mid-Wales.      


Pulling up a second chair so I might watch, John put the radio token system through its paces for me. Each of the screens held a schematic track diagram-- essentially a computerized model board.  Together the three consoles covered the entire line from Shrewsbury over the English border down to Machynlleth, and from Dovey Junction on to Aberystwyth in the south and Pwllheli in the north.  As John explained it, the cab of each train on the line was equipped with brackets and a data socket, into which the driver could plug a small portable video terminal.  A radio data link connects the terminal in each train to John's central facility.  Using his keyboards, John can set up routings on his screens, and then assign movement authority to individual trains by transmitting a "radio token" to the driver.  Once John transmits the token, a set of repeater stations relays the signal to the train out on the line.  An onboard computer decodes the signal and displays the new movement authority on the cab video screen, and the driver opens up the throttle and proceeds into the track for which he now holds the "token."


As I followed John's explanation, I was struck by the way the BR and its successor Railtrack had gone back to the future in designing the system.  Saddled with an aging and expensive physical plant of lineside signals and interlocking towers for controlling train movements on the Cambrian lines, BR knew that it needed to cut costs: the alternative might be partial or full closure of the entire route.   In response, they decided to replace the expensive lineside signaling equipment with a compact and up-to-date system of computers, video screens, and radio data links.   Yet conceptually, the Radio Token system represents a return to the fundamental practices of the steam era.  Though video consoles and radio signals replace the electromechanical token machines and their metal chits, there is no functional difference between Railtrack's Radio Token dispatching and the Victorian ways of the tiny Talyllyn Railway.  



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All materials, images, text and presentation copyright 1998 Erik Gray Ledbetter.  See Terms of Use.