What is the speed limitation for a train or engine operating on tracks other than the main track?

The speed limitation for a train or engine operating on tracks other than the main track is defined as "Restricted Speed not exceeding 10 mph." This speed restriction is specifically put in place for safety reasons, as trains may encounter various hazards on tracks that are not main lines, such as work crews, other rail vehicles, or equipment.

Restricted speed means that the train must be able to stop within half the distance of what is visible ahead, allowing for quick responses to any unforeseen circumstances. Because non-main track areas can be more unpredictable and may have less clear visibility, maintaining a lower speed significantly reduces the risk of accidents and enhances safety for both the train crew and any personnel who may be working on or near the tracks.

The other choices represent speeds that either exceed the safety parameters outlined for tracks other than the main track or do not apply under the specific regulations that govern restricted speeds. Thus, the chosen answer accurately reflects the guidelines established for train operations in these more variable environments.