Does anyone know if the Southern Pacific Railway used CTC signals? If not then that type, ABS or APB?
Yes to CTC and ABS for train signaling. What is APB?
You need to refine your question to where and when as the Espee was a very large road.
CTC is not so much a signal system as an operating system using signal indication to convey the dispatcher’s orders, distinct from timetable and train order or track warrant control or direct train control. John Armstrong, in his articles in TRAINS which were reprinted as “All About Signals”, compared CTC to a very stretched out interlocker.
APB is Permissive Block
Tom
Yes the SP{ used CTC, ABS, and APB in at least one location. The track from Montalvo to Oxnard was APB, operated by the Oxnard operator (one of which I was)