Canadian National Railroad Practice Exam

In Non-CTC territory, Track Authority limits are defined by clearly identifiable locations along the track, not by a single kind of reference. This means the limits can be described using mile posts, station names, or other easily recognizable points—whatever provides a precise start and end for the authority. Using a variety of identifiable points ensures crews can verify exactly where the authority begins and ends on the ground, even where one type of marker isn’t present.

That flexibility is why designation by mile posts, station names, or other clear reference points is the correct approach. Limiting limits to only mile posts, only station names, or only track numbers would ignore other practical reference points that might be used on the line.