Typically (by rule and regulation) a train can't clear or enter a CTC main from/to other than main track or a siding unless there is a electric locked switch or absolute signal. There is an exception that allows entering CTC without a signal or electric lock but speed limit in that territory for main track must be kept fairly slow (20-25 mph?) - more of an FRA interpretation thing. Wallula, WA has two hand throw crossovers that the DS can give you authority to enter the main through.

Don't know nuthin about PTC other than current UP policy is PTC is not required for another railroad for interchange under 5 miles of UP mainline running.