Upon its opening in 1968, London Underground's Victoria Line was the most advanced railway in the world, boasting complete automation of scheduling, signalling and almost all train operations. The driver opened and closed the passenger doors, and pressed a pair of buttons to start the train, but all further operation was automatic.
Technology of the time was changing very quickly. Elsewhere in industry, computers has started making inroads into production and operations. With passenger safety at its heart, any changes in railway technology were gradual, and only after long-term rigorous testing. There were no computers on our new line, instead what we have is an enormous state machine, comprising a mixture of electro-mechanical and electro-pneumatic systems, along with some early digital logic, providing a complete automation system.
The Victoria Line simulator is the result of a three year project to turn the 60 volumes of signalling-related bookwiring (the Victoria line's circuit diagrams) into a complete software simulation representing every aspect of the automatic line.
The Victoria Line, being an entirely new line, took advantage of the new technology of the time where possible, whilst relying on tried and tested safety systems.
The completed line comprised 16 stations and a depot. Nine of these had either a junction or reversing facility that required safe control of the passage of trains. Each of these was provided with a Westinghouse 'Style V' lever frame that electrically operated points and signals. It retains the traditional mechanical interlocking that ensures that levers are physically prevented from being able to set up an unsafe or conflicting paths for trains. These lever frames are mounted vertically, which saves space in cramped underground rooms, and the levers move from right-to-left, instead of the traditional back-to-front.
The intensity of the proposed service would make it impossible for a signalman to operate the levers for any length of time. Instead the levers were air-operated by a route controller (known as the Lever Operations Board) which was wired to pull the correct point and signal levers in the right order when a particular destination was requested - and how to put them back afterwards.
On top of this, an automation system, known as the Programme Machine, held the timetable on a plastic roll containing a rows of punched holes - on row representing each train. The departure time and train details on the roll would be compared against reality, and when everything matched, the appropriate route would be requested via the Lever Operations Board. Once the train had passed, the Programme Machine would step to the next row of holes ready for the next train.
To complete the automation system, an Automatic Train Operation system was designed such that the state of the track occupation ahead was fed to the train behind via the track so it knew whether to accelerate or to slow down, and ultimately when to stop at a station.
Finally, a control room was provided to give signallers a complete overview of the line and of the nine automated signalboxes (known as Interlocking Machine Rooms). This had a desk with buttons that allowed the signalman to override the signalling automation in the event of operational incidents.
The automation systems were designed in-house by London Underground by a team headed by the then Chief Signal Engineer, Robert Dell. Dell was born in 1900 and served London Underground for 54 years. The Victoria Line can be conisdered the pinnacle of his career.
Mechanical lever-frame signalboxes can be seen at almost every preserved railway centre around the country, and their usage and operation is comparatively simple to explain.
Less well represented in preservation are miniaturised lever frames despite some, such as the Westinghouse style 'B' lever frame, date back to 1902.
Very poorly represented in preservation are the later developments in signalling that severed the direct link between signalman and the levers he pulled. Early automation allowed the signalman to press a single button which would cause the appropriate levers for the points and signals to be pulled electro-pneumatically on his behalf (and returned after the passage of the train). Further automation of scheduling and train operations occured without computers, but there is little to show for this equipment in preservation, let alone how it operated.
The Victoria Line Simulator is an attempt to preserve both the equipment and operational knowledge of this pre-computer era of railway signalling history.