SVNO Control System
The SVNO will be controlled with Arduino PLC's and some custom designed, purpose built circuits. Yards, Branches and sidings will be manually controlled from the locations. However the mainline signals, and controlled sidings will be controlled automatically, or VIA a dispatcher.
Mainline Track Occupancy detection.
The plan is to have detection circuits like this at each CP. The Photo sensors are all connected to a localized OR gate which will produce a 'Occupancy' detection if any of them are blocked. The 'HE' symbols are Hall Effect sensors which are located in the trackbed. These sensors will detect the direction of the train. For this to work, every locomotive and rail car will have a small rare earth magnet placed below it. Only mainline track has occupancy detection. The only exception will be Thomson Bay controlled siding, which will have occupancy detection at either end of the siding.
Manual sidings do not have occupancy detection.
Prototypically, today most signal circuits default to Red, or stop when no trains or movement is detected. However this system will default to clear or Green when no occupancy is detected. This will allow trains to enter the mainline, at their own will, as long as the signal is green. Once a train enters the mainline, they will be detected at the first CP next to the switch (CP1 in the diagram). This will automatically turn the opposing signals Red, as well as the previous signal. The lights in the trains direction of travel will continue to display green unless occupancy is detected further down the line, in which case there will be a 1 block red protection gap.