Ian Stewart wrote about calculational train circuits like these in an article in Scientific American in 1994 :

“A Subway Named Turing”

Subscription-required link : https://www.nature.com/scientificamerican/journal/v271/n3/pd...

Love the closing line (as the train passengers discussing the concept of train logic circuits realise they haven’t come to a station in awhile):

>“This isn't any touring machine," the guard said indignantly. "This is a personnel commuter, buddy." >At least, I think that's what he said.