When are trains required to stop and protect grade crossings

The requirement for Excepted and Class 1-3 track is inspect weekly or before a train movement if used less than once a week. As you mentioned, most irregularly used track is inspected on the day of a train movement. The inspector usually goes out in the early morning and gets the inspection done and reports clear before the train starts out. Inspection running immediately ahead of the train is awkward because the inspector has to stop to check any suspected defects and all switches have to be inspected on foot at least once a month.

Class 4 and 5 track is maintained to high "main line" standards and needs to be hi-railed at least twice a week and have a Sperry Car rail defect inspection at least once a year.

Class 1-3 still require reasonable branch line type maintenance including vegetation control and drainage. The difference between these classes is in the tolerance for gauge and surface measurements and number of good ties per rail. A RR can stretch out the time before they need to do a major tie and surface job by lowering speeds and downgrading the track to a lower class.

Excepted track can indeed be very poorly maintained as long as it is not more than 1.75 inches over gauge but is does still have to be inspected to be sure it is not so bad that the train may derail.

The only time we are required to flag crossings is when:

+ The gates/lights are out of service/not working. This is indicted on your General Track Bulletin or given verbally by a dispatcher.

+ When shaving cars ahead of an engine over a crossing.

There are other off-the-wall condictions that would require us to flag the crossing, but they're rare. The two above are why we have to most of the time.

Then there's the old dictum...."When in doubt, take the SAFE course"...ie
Stop and protect.