I think you hit the nail on the head with trains, because your parent is pretty much describing a modern train signaling system, down to the centralized superco

I think you hit the nail on the head with trains, because your parent is pretty much describing a modern train signaling system, down to the centralized supercomputer. > create standardised computer readable infrared road markings, equip each traffic light and each lamp post with a radio beacon, each crash barrier could have a radio marker, create PUBLIC maps of each city, have a central traffic control sypercomputer in each city provide directions to cars. Have each car painted with infrared markers so they recognise each-other. It is amazing how often tech savy folks can reinvent trains.