Its worse than you think. I can't find the source right now but IIRC the NYC subway signals still run on the vacuum tube system designed in the early 1900s. At

Its worse than you think. I can't find the source right now but IIRC the NYC subway signals still run on the vacuum tube system designed in the early 1900s. At the time it was a massive technical accomplishment. Every small arrangement of vacuum tubes is like a purpose built computer for signaling a specific section of track with speeds and spacing pre-calculated. It successfully put an end to high profile accidents caused by human error. Today you could do the same thing with a micro-controller for almost no money.