"Other than main track" is not "restricted speed" (per GCOR), but falls under rule 6.28.

I have heard in the past claims of running trains on branches listed as "other than main track" at high speeds - as long as they were able to "stop within one-half the range of vision". This is where the dark territory speed limits would apply (49 mph for freight; maybe 59 mph for passenger IIRC).

I have also heard that the FRA interpretation is that any train speed over 20 mph requires some form of dispatching or track authority (ABR, CTC, DT/ABS).

I have never found this in writing one way or the other, so there are plenty of "experts" out there that go by the wording of the rules and not neccessarily using common sense when applying them.

The passenger tracks in front of the San Diego depot are all main tracks. I think this has more to do with the need to blue flag the equipment without having to lock out the CTC controlled switches at the top end.

Restricted speed puts a whole lot of responsibility on the engineer to know what they are doing. My worst surprise was just after going through a malfunction junction (very busy road intersection with the tracks going through at an angle) only to find the lazy yard job had left the switch lined wrong for the wye. I needed to back up a couple cars on that one.

The whole shake and bake training fallout will only get worse. Amtrak usually only requires a year of experience as an A/C. (I think Modoc claims to have some students hired as engineers) Once all the pre-1985 conductors retire, most of the freight railroads will never have a conductor with more than a few years experience at most, even though they are jointly responsbile with the engineer for the train. But hey - PTC will fix everything - and don't be surprised if within 5 years most mainlines are engineer only.